液压系统的外文文献翻
液压动力系统中英文对照外文翻译文献
中英文对照外文翻译文献(文档含英文原文和中文翻译)原文：FEATURE-BASED COMPONENT MODELS FOR VIRTUALPROTOTYPING OF HYDRAULIC SYSTERMAbstract:This paper proposes a feature-based approach for the virtual prototyping of hydraulic systems. It presents a framework which allows the designer to develop a virtual hydraulic system prototype in a more intuitive manner, i.e. through assembly of virtual components with engineering data. The approach is based on identifying the data required for the development of the virtual prototypes, and separating the information into behaviour, structural, and product attributes. Suitable representations of these attributes are presented, and the framework for the feature-based virtual prototyping approach is established,based on the hierarchical structure of components in a hydraulic system. The proposed framework not only provides a precise model of the hydraulic prototype but also offers the possibility of designing variation classes of prototypes whose members are derived by changing certain virtual components with different features.Key words: Computer-aided engineering; Fluid power systems;Virtualprototyping1.IntroductionHydraulic system design can be viewed as a function-to-form transformation process that maps an explicit set of requirements into a physical realisable fluid power system. The process involves three main stages: the functional specification stage,the configuration design stage, and the prototyping stage.The format for the description of the design in each stage is different.The functional specification stage constitutes the initial design work. The objective is to map the design requirements. To achieve this, the design problems are specified Correspondence and offprint requests to: Dr S. C. Fok, Schoool of Mechanical and Production Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798. The designer must identify the performance attributes, which can include pressure, force, speed, and flowrate, with the required properties such as size, cost, safety and operating sequence. performance requirements for each attribute. In this stage, the design is abstracted in terms of the performance attributes with associated values.The objective of the configuration design stage is to synthesise a hydraulic circuit that performs the required functions conforming to the performance standards within defined constraints. A typical hydraulic system is made up of many subsystems. The smallest building block in a subsystem is the standard hydraulic component (such as valves, cylinders,pumps, etc.). Each type of standard component serves a specific elemental function. The design effort in the configuration design stage is fundamentally a search for a set of optimal arrangements of standard components (i.e. hydraulic circuit) to fulfil the functional requirements of the system. Based on this framework, the designers would normally decompose the overall system functions in terms of subfunctions. This will partition the search space and confine the search for smaller hydraulic subcircuits to perform the subfunctions.Computers are often used to support the configuration design process. For example, Kota and Lee devised a graph-based strategy to automate the configuration of hydraulic circuits. After the development of the hydraulic circuits, digital simulation tools are often used to study and evaluate these configurations. With these tools, designers can compare the behaviour of different circuits and also analyse the effects when subcircuits are combined. In the configuration design stage, the design is traditionally represented as a circuit drawing using standard icons to symbolise the type of standard component. This is a form of directed graph S(C,E) where the circuit S contains components C in the form of nodes with relations between components denoted by edges E.The prototyping stage is the verification phase of the system design process where the proposed hydraulic circuit from the configuration design stage isdeveloped and evaluated. Physical prototyping aims to build a physical prototype of the hydraulic system 666 S. C. Fok et al. using industrial available components. The process of physical prototyping involves the following: Search for appropriate standard components from different manufacturers. Pre-evaluation and selection of components based on individual component cost, size, and specification, and compatibility factors between components. Procurement and assembly of the selected components.Test and evaluate the physical prototype based on the overall system requirements. Use other components or redesign the circuit (or subcircuits)if necessary.Besides dynamics, the development of the physical prototype must take into consideration other factors including structure,cost, and weight. The dynamics data are used to confirm the fluid power system behaviour whereas the geometric information is used to examine the assembly properties. The development of the physical prototype will provide the actual performance,structure, and cost of the design.The main disadvantage of physical prototyping is that it is very tedious and time consuming to look for a set of suitable combinations of standard components from among so many manufacturers. Although the basic functions of the same types of standard component from different manufacturers do not differ, their dynamics, structural and cost characteristics may not be similar, because of design variation. Hence, for a given hydraulic circuit, different combinations of parts from differentmanufacturers can have implications on the resulting system,in terms of dynamics, structure, and cost. Value engineering can be used at this stage to improve the system design by improving the attributes at the component level. This includes maximizing the performance-to-cost ratio and minimising the size-to-performance ratio. Virtual prototyping can be viewed as a computer-aided design process, which employs modelling and simulating tools to address the broad issues of physical layout, operationalconcept, functional specifications, and dynamics analysis under various operating environments. The main advantage of virtual prototyping is that a hydraulic system prototype can be assembled, analysed, and modified using digital computers without the need for physical components, thus saving lead time and cost.The main requirement of a virtual hydraulic system prototype is to provide the same information as a physical prototype for the designer to make decisions.To achieve this, the virtual prototype must provide suitable and comprehensive representations of different data. Furthermore, transformation from one representation to another should proceed formally. Xiang et al. have reviewed the past and current computer-aided design and prototyping tools for fluid power systems. The work revealed that the current tools could not provide a completerepresentation of the design abstractions at the prototyping stage for design judgement. Most of the tools concentrate on the dynamics behaviour. Vital geometrical and product information that relates to the system prototype consideration and evaluation is frequently missing.To advance the development of computer-aided virtual prototyping tools for fluid power systems, there is a need to address the formal representations of different abstractions of behaviour,structural, and product data along with their integration. This paper focuses on these issues and proposes the formalism of a unified component model and the taxonomy based on the feature-based approach. In Section 2, we discuss the feature- based approach focusing on the key information and their representations required for hydraulic system prototyping. Section 3 presents a formalism of the feature-based model and structure for the development of virtual hydraulic system prototypes.The structure is illustrated with an example. Future work and conclusions are given in Section 4.2. Feature-Based ApproachFeatures can be defined as information sets that refer to aspects of attributes that can be used in reasoning about the design, engineering or manufacturing processes. The concept of using features to integrate CAD/CAPP/CAM is not new and there are many papers on the application of this approach in CIM. In all these applications, the feature model is regarded as the basis whereas design by features is the key for the integration. To develop a feature model, the relevant information concerning the design must be identified and grouped into sets based on the nature of the information. The relevant information should contain sufficient knowledge for activities such as design, analysis, test, documentation, inspection, and assembly, as well as support various administrative and logistic functions. Design by features is the process of building a model of the design using features as primitive entities. The feature model provides the standardisation of relevant data. Through the design by features approach, vital knowledge of the design will be generated and stored. Together, the feature model and the design by features approach will provide the essential information, which can be used, not only for the simultaneous consideration of many different concerns with the design, but also to interface the many activities in the design realisation process, including the life cycle support operations. The main drawback of the feature-based design approach is that the feature model should be properly defined . This can be difficult, as features are sets of knowledge that are application dependent. The organisation of the features can also be application specific. Non-trivial data-management problems could arise if the feature model is not properly defined. To avoid these problems, the type,representation and structure of the features should be resolved prior to using the feature-based design methodology. The main concern when developing afeature model is that it is application-specific. In the domain of virtual prototyping of hydraulic systems, the details of the constituent standard components must be able to be used to describe the overall system. The component features are bearers of knowledge about that part. To create a suitable feature model for hydraulic system design based on the assembly of standard components, the relevant information associated with various standard components must be identified and classified. This definition Feature-Based Component Models 667 of the component feature set can then be extended to encompass the subsystem feature set based on the hierarchical structure between the components in the subsystem. In the same manner, a hierarchical structure for the hydraulic system feature representation would evolve by considering the system as a hierarchy of subsystems.The necessary information required for a proper description of the virtual prototype must be no less than that derived by the designer from a physical prototype for decision making. These data should generally include the shape, weight, performance properties, cost, dimensions, functionality data, etc. Comparison with the physical prototyping process, the information required for each standard component could be separated into three distinct groups: behaviour attributes, structural attributes, and product attributes.2.1 Behaviour AttributesThe behaviour of a hydraulic component can be defined in terms of the dynamics characteristics used to satisfy the functional requirements. Consider a hydraulic cylinder connected to a load. Its function is to transmit a force from the stroke of the piston to the load. The maximum force it can transmit can be used to define the functionality and the behaviour requirements can be specified in terms of the desired load acceleration characteristics. Hence for a hydraulic component, behaviour attributes express functionality and can be reflected in the dynamics characteristics. The designer is responsible for the proper definition of the overall system behaviour characteristics in terms of the desired dynamics. A standard component will have its own behaviour and provide a specific plex functions that cannot be achieved by a single standard component are derived using a combination of components. Hence, the behaviour of the standard component will play an important role as the individual behaviours of components together with their arrangement can alter the overall system function .The behaviour of a standard component can be nonlinear and can be dependent on the operating conditions. When two components are combined, it is possible that their behaviours can interact and produce undesired or unintended characteristics. These unwanted behaviours are assumed to have been resolved during the configuration design stage. The hydraulic circuit used in theprototyping stage is assumed to be realisable and without any undesirable interacting behaviours. This means that the output behaviour of a component will provide the input to the subsequent component.The representation of behaviours for hydraulic systems has been widely investigated. These representations include transfer functions, state-space and bond graphs. Transfer functions (for single-input–single-output systems) and state-space equations (for multiple-input–multiple-output systems) are based on the approximation of the dynamics about a nominal operating condition. The power bond graph model is based on the causal effects that describe the energy transformations in the hydraulic system. This approach is appealing for hydraulic system analysis. The main disadvantage is that the derivation of the dynamics equation in a bond graph of a complicated fluid power system can become very tedious. As a result, recent work has concentrated on the used of artificial intelligence to represent the nonlinear mapping between the input and output data, which can be obtained via experimental work. These nonlinear mappings can be accomplished using artificial neural networks .It is quite natural for a hydraulic system designer to use input–output data to describe the behaviour of a hydraulic component. The configuration design of a hydraulic system is often achieved through steps of function decomposition. To design a hydraulic system, the designer often tries to decompose the functions and their requirements down to the component level.译文：基于原型液压系统特征的机构模型摘要：本文为原型液压系统的设计提出了一种基于特征的方法。
混凝土泵车液压系统的认识外文文献翻译、中英文翻译
译文原文：Understanding of concrete pump hydraulic systemItalian CIFA Concrete Machinery Company(1.CIFA concrete mechanical pump Institute, Italy)Pumping Hydraulic systemBoom hydraulic systemOutrigger hydraulic systemHydraulic system diagramDaily check and maintenance of the hydraulic systemThe functions of the truck mounted concrete pump, hydraulic system can be divided into pumping hydraulic system, boom hydraulic system, outrigger hydraulic system.Pumping Hydraulic system Is divided into three parts: main pumping system, distribution and lubricating system, mixing and cooling and cleaning system.Main pumping systemThere are two hydraulic loops: open and close loop.The Open loop: uses an A11VLO190 variable displacement of axial piston pump. It is fitted with a constant power control device, pressure cut-off valve and electricalstroke limiter with proportional solenoid. The constant power control device has been set in the factory. The displacement can be adjusted from 0 to Maximum by turning the oil pump displacement potentiometer on the control panel from low to high.Fig. 1 A11VLO 190A，B Service port (without charging pump) 420 barS Suction port (with charging pump) 35 barT1, T2 Air bleed, tankR Air bleed, oil drainM1 Measuring point, regulating chamberM Measuring point, service portG Port for positioning pressure (controller) for version with stroke limiter (H.., U2), HD and EP with screw ed fitting GE10 – PLM (otherwise port G closed)The other is the control line, which can change the flow direction and the displacement of main pump through constant power valve, proportional solenoid pressure reducing valve, directional control valve and servo valve of main pump.The Closed loop: There is an auxiliary pump with relief valve that the setting pressure is 3.5Mpa in A4VG180. The auxiliary pump has two output ways. One is the charge oil line, which connects with suction line of main pump through the check valve in two pressure relief valves and add oil to main pump. At the same time excessive hydraulic oil return to oil tank through flushing valve and cooler to realize heat exchange for closed loop.A, B Service line ports SAE 1 1/4", high pressure series 420 barT1 Case drain or filling portT2 Case drain M33×2; 18 deepM A, M B Pressure gauge - operating pressure A, BR Air bleedS Boost suction portX1, X2Control pressure ports (before the orifice)G Pressure port for auxiliary circuitP S Control pressure supplyFa Filter outletFa1Filter outlet (filter assembly)Fe Filter inlet M33×2; 18 deepF S Port from filter to suction line (cold start)M H Port for balanced high pressureY1, Y2Remote control ports (only for HD control)Flushing valveUsed for closed loop to prevent excessive heat build-up in closed circuit operation. The setting pressure of flushing valve is 3.0MPaPressure reducing valve with proportional solenoidUsed for closed loop. The Output pressure is connected with the remote control port of main pump to control the displacement and is controlled by a proportional current signal and constant power valve. The displacement can be adjusted from 0 to Maximum by turning the displacement adjusting potentiometer.Constant power valveUsed for closed loop. When the hydraulic system pressure is over the setting pressure, the valve works to reduce the output pressure of the pressure reducing valve and maintain the constant power.Pilot pressure setting Power settingFig.3 Constant power valveMain pump suction filterOpen loop: filtration fineness 100u.Close loop: filtration fineness 20u.When the indicator in the vacuum gauge exceeds the safe area or the electric signal instrument gives a warning, the cartridge may be blocked. It should be clean or replace filter cartridge promptly.Filter filtration fineness is 20u in open loop. When the reading pressure of the vacuum gauge exceeds 0.35Mpa, the cartridge may be blocked. It should be clean orReturn filterreplace filter cartridge promptly.Filter filtration fineness is 10u in closed loop. When the electricity deliver reports to the police, the cartridge may be blocked, it should be clean or replace filter cartridge promptly. Distribution and lubricating systemConstant pressure pumpSetting screw for pressurecontrol zero /Stroke pressureFig.4 Constant pressure pumpAn A10VO28 constant pump is used for the distribution system of supply oil.The setting of the pressure control valve of the pump is 16Mpa. Once the system pressure is reached,the bump will keep this pressure then decrease the displacement. There is a pressure relief valve in the distribution circuit to act as a safety valve, which is set to 18Mpa.Plate ball valve (shut-off valve)Used to discharge the accumulator. It must be rotated the lever of shut-off valve anti-clockwise when the pumping finishes or stopped for maintenance, in order to discharge the pressure of theaccumulator. (Pressure gauge of distribution system is zero) AccumulatorInflation pressure is 8-9Mpa. Use Only Nitrogen to fill the accumulator. Charging pressure should not exceed these figures.Lubricating systemThere are two types. One is reciprocating centralized lubrication that is driven by oil from the swing cylinders of distribution system includes lubricating single pump (or double pump), distributor, damper and filter. The other is automatic centralized lubrication that is driven by a D.C motor with an independent grease tank and independent from the hydraulic system. The interval time of lubrication is carried out in the factory. The lubrication system works automatically when pumping.Mixing, cooling, cleaning systemOnly the Mixing, cooling, cleaning system are driven by motor in open loop.Gear pumpGear pump supplies oil to the mixing, cooling, cleaning system.Sandwich type relief valveThe pressure is set to 14Mpa.Ressure relayIf the mixing blade is stuck, the system pressure will raise. When the pressure exceeds the setting value (usually 10Mpa), the pressure relay will give a warning. The Solenoid directional control valve changes direction to let the mixing motor to rotate anti-clockwise. After 6 second the solenoid valve will reset, and the mixing motor will rotate clockwise again. Return filterThe filtration fineness is 10u in closed loop. The cartridge may be blocked when the electric alarm sounds. It should be replace promptly.Boom hydraulic systemBoom pumpBoom and outrigger use the same pump.37m and 40m truck mounted concrete pumps: A2FO23 fixed displacement pump44m and 47m truck mounted concrete pumps: A7VO55LRDS variable displacement pump, or A7VO55DRS variable displacement pump46m and 49m truck mounted concrete pumps: A7VO55LRDS variable displacement pumpFig.5 A7VO55DRS Fig.6 A7VO55LRDS Fig.7 A2FO23 Boom proportional directional spool valveThe proportional directional spool valve with electro-hydraulic consists of pressure relief valve, pressure reducing valve, and flow control valve, and can becontrolled manual or by remote control.Fig.8 Boom proportional directional spool valveLoad-holding valveLoad-holding valve has three functions. (1) It acts as a lock when the cylinder isn’t moving. (2) Load-holding valve has twice relief function to protect boom against vibrating. It will be adjusted in the factory. (3) When the boom moves downward asSlewing load-holding valvegravity load, it can limit speed to prevent the boom falling too quickly and shaking.There are three main functions. Lock, overload protection and speed limiting. Outrigger hydraulic systemOutrigger hydraulic system and boom hydraulic system are used the same pump to supply oil. Outriggers should be set up before the boom is operated by the control levers or electric control button on both sides of the truck mounted concrete pump.Outrigger proportional directional spool valveIt is an integrated unit with a relief valve inside to control maximum pressure of the outrigger hydraulic system.Fig .9 Outrigger proportional directional spool valveOutrigger hydraulic lockIt is used to lock the outrigger cylinders and pay attention to the vertical moving of the outrigger cylinder when working .Pressure relief valve中文译文：混凝土泵车液压系统的认识意大利 CIFA 混凝土机械公司（1.CIFA 混凝土机械泵车研究所, 意大利，）泵送单元液压系统臂架液压系统 支腿液压系统 液压原理图液压系统的日常保养及维护泵车液压系统按泵车功能可划分为泵送单元液压系统、臂架液压系统、支腿液压系统。
中英文文献翻译-混凝土泵车液压系统的认识
附录附录AUnderstanding of concrete pump hydraulic systemPumping Hydraulic systemBoom hydraulic systemOutrigger hydraulic systemHydraulic system diagramDaily check and maintenance of the hydraulic systemThe functions of the truck mounted concrete pump, hydraulic system can be divided into pumping hydraulic system, boom hydraulic system, outrigger hydraulic system.Pumping Hydraulic system Is divided into three parts: main pumping system, distribution and lubricating system, mixing and cooling and cleaning system.Main pumping systemThere are two hydraulic loops: open and close loop.The Open loop: uses an A11VLO190 variable displacement of axial piston pump. It is fitted with a constant power control device, pressure cut-off valve and electrical stroke limiter with proportional solenoid. The constant power control device has beenset in the factory. The displacement can be adjusted from 0 to Maximum by turning the oil pump displacement potentiometer on the control panel from low to high.Fig. 1 A11VLO 190A，B Service port (without charging pump) 420 barS Suction port (with charging pump) 35 barT1, T2 Air bleed, tankR Air bleed, oil drainM1 Measuring point, regulating chamberM Measuring point, service portG Port for positioning pressure (controller) for version with stroke limiter (H.., U2), HD and EP with screwed fitting GE10 – PLM (otherwise port G closed)The other is the control line, which can change the flow direction and the displacement of main pump through constant power valve, proportional solenoid pressure reducing valve, directional control valve and servo valve of main pump.The Closed loop: There is an auxiliary pump with relief valve that the setting pressure is 3.5Mpa in A4VG180. The auxiliary pump has two output ways. One is the charge oil line, which connects with suction line of main pump through the check valve in two pressure relief valves and add oil to main pump. At the same time excessive hydraulic oil return to oil tank through flushing valve and cooler to realize heat exchange for closed loop.A, B Service line ports SAE 1 1/4", high pressure series 420 barT1 Case drain or filling portT2 Case drain M33×2; 18 deepM A, M B Pressure gauge - operating pressure A, BR Air bleedS Boost suction portX1, X2Control pressure ports (before the orifice)G Pressure port for auxiliary circuitP S Control pressure supplyFa Filter outletFa1Filter outlet (filter assembly)Fe Filter inlet M33×2; 18 deepF S Port from filter to suction line (cold start)M H Port for balanced high pressureY1, Y2Remote control ports (only for HD control)Flushing valveUsed for closed loop to prevent excessive heat build-up in closed circuit operation. The setting pressure of flushing valve is 3.0MPaPressure reducing valve with proportional solenoidUsed for closed loop. The Output pressure is connected with the remote control port of main pump to control the displacement and is controlled by a proportional current signal and constant power valve. The displacement can be adjusted from 0 to Maximum by turning the displacement adjusting potentiometer.Constant power valveUsed for closed loop. When the hydraulic system pressure is over the setting pressure, the valve works to reduce the output pressure of the pressure reducing valve and maintain the constant power.Fig.3 Constant power valveMain pump suction filterOpen loop: filtration fineness 100u.Close loop: filtration fineness 20u.When the indicator in the vacuum gauge exceeds the safe area or the electric signal instrument gives a warning, the cartridge may be blocked. It should be clean or replace filter cartridge promptly.Filter filtration fineness is 20u in open loop. When the reading pressure of the vacuum gauge exceeds 0.35Mpa, the cartridge may be blocked. It should be clean or Return filterreplace filter cartridge promptly.Filter filtration fineness is 10u in closed loop. When the electricity deliver reports to the police, the cartridge may be blocked, it should be clean or replace filter cartridge promptly.Distribution and lubricating systemConstant pressure pumpFig.4 Constant pressure pumpAn A10VO28 constant pump is used for the distribution system of supply oil.The setting of the pressure control valve of the pump is 16Mpa. Once the system pressure is reached, the bump will keep this pressure then decrease the displacement. Thereis a pressure relief valve in the distribution circuit to act as a safety valve, which is set to 18Mpa.Plate ball valve (shut-off valve)Used to discharge the accumulator. It must be rotated the lever of shut-off valve anti-clockwise when the pumping finishes or stopped for maintenance, in order to discharge the pressure of theaccumulator. (Pressure gauge of distribution system is zero) AccumulatorInflation pressure is 8-9Mpa. Use Only Nitrogen to fill the accumulator. Charging pressure should not exceed these figures.Lubricating systemThere are two types. One is reciprocating centralized lubrication that is driven by oil from the swing cylinders of distribution system includes lubricating single pump (or double pump), distributor, damper and filter. The other is automatic centralized lubrication that is driven by a D.C motor with an independent grease tank and independent from the hydraulic system. The interval time of lubrication is carried out in the factory. The lubrication system works automatically when pumping.Mixing, cooling, cleaning systemOnly the Mixing, cooling, cleaning system are driven by motor in open loop.Gear pumpGear pump supplies oil to the mixing, cooling, cleaning system.Sandwich type relief valveThe pressure is set to 14Mpa.Ressure relayIf the mixing blade is stuck, the system pressure will raise. When the pressure exceeds the setting value (usually 10Mpa), the pressure relay will give a warning. The Solenoid directional control valve changes direction to let the mixing motor to rotate anti-clockwise. After 6 second the solenoid valve will reset, and the mixing motor will rotate clockwise again.Return filterThe filtration fineness is 10u in closed loop. The cartridge may be blocked when the electric alarm sounds. It should be replace promptly.Boom hydraulic systemBoom pumpBoom and outrigger use the same pump.37m and 40m truck mounted concrete pumps: A2FO23 fixed displacement pump44m and 47m truck mounted concrete pumps: A7VO55LRDS variable displacement pump, or A7VO55DRS variable displacement pump46m and 49m truck mounted concrete pumps: A7VO55LRDS variable displacement pumpFig.5 A7VO55DRS Fig.6 A7VO55LRDS Fig.7 A2FO23Boom proportional directional spool valveThe proportional directional spool valve with electro-hydraulic consists of pressure relief valve, pressure reducing valve, and flow control valve, and can becontrolled manual or by remote control.Fig.8 Boom proportional directional spool valveLoad-holding valveLoad-holding valve has thre e functions. (1) It acts as a lock when the cylinder isn’t moving. (2) Load-holding valve has twice relief function to protect boom against vibrating. It will be adjusted in the factory. (3) When the boom moves downward asSlewing load-holding valvegravity load, it can limit speed to prevent the boom falling too quickly and shaking.There are three main functions. Lock, overload protection and speed limiting.Outrigger hydraulic systemOutrigger hydraulic system and boom hydraulic system are used the same pump to supply oil. Outriggers should be set up before the boom is operated by the control levers or electric control button on both sides of the truck mounted concrete pump.Outrigger proportional directional spool valveIt is an integrated unit with a relief valve inside to control maximum pressure of theoutrigger hydraulic system.Fig .9 Outrigger proportional directional spool valveOutrigger hydraulic lockIt is used to lock the outrigger cylinders and pay attention to the vertical moving of the outrigger cylinder when working .Pressurerelief附录B混凝土泵车液压系统的认识泵送单元液压系统 臂架液压系统 支腿液压系统 液压原理图液压系统的日常保养及维护泵车液压系统按泵车功能可划分为泵送单元液压系统、臂架液压系统、支腿液压系统。
液压系统外文文献翻译、中英文翻译、外文文献翻译
附录Hydraulic SystemHydraulic presser drive and air pressure drive hydraulic fluid as the transmission is made according to the 17th century, Pascal's principle of hydrostatic pressure to drive the development of an emerging technology, the United Kingdom in 1795 •Barman Joseph (Joseph Barman, 1749-1814), in London water as a medium to form hydraulic press used in industry, the birth of the world's first hydraulic press. Media work in 1905 will be replaced by oil-water and further improved.After the World War I (1914-1918) ,because of the extensive application of hydraulic transmission, especially after 1920, more rapid development. Hydraulic components in the late 19th century about the early 20th century, 20 years, only started to enter the formal phase of industrial production. 1925 Vickers (F. Vickers) the invention of the pressure balanced vane pump, hydraulic components for the modern industrial or hydraulic transmission of the gradual establishment of the foundation. The early 20th century G • Constantia scofluctuations of the energy carried out by passing theoretical and practical research; in 1910 on the hydraulic trans- mission (hydraulic coupling, hydraulic torque converter, etc.) contributions, so that these two areas of development.The Second World War (1941-1945) period, in the United States 30% of machine tool applications in the hydraulic transmission. It should be noted that the development of hydraulic transmission in Japan than Europe and the United States and other countries fornearly 20 years later. Before and after in 1955, the rapid development of Japan's hydraulic drive, set up in 1956, "Hydraulic Industry." Nearly 20 to 30 years, the development of Japan's fast hydraulic transmission, a world leader.Hydraulic transmission There are many outstanding advantages, it is widely used, such as general industrial use of plastics processing machinery, the pressure of machinery, machine tools, etc.; operating machinery engineering machinery, construction machinery, agricultural machinery, automobiles, etc.; iron and steel industry metallurgical machinery, lifting equipment, such as roller adjustment device; civil water projects with flood control and dam gate devices, bed lifts installations, bridges and other manipulation of institutions; speed turbine power plant installations, nuclear power plants, etc.; ship from the deck heavy machinery (winch), the bow doors, bulkhead valve, stern thruster, etc.; special antenna technology giant with control devices, measurement buoys, movements such as rotating stage; military-industrial control devices used in artillery, ship anti- rolling devices, aircraft simulation, aircraft retractable landing gear and rudder control devices and other devices.A complete hydraulic system consists of five parts, namely, power components, the implementation of components, control components, auxiliary components and hydraulic oil.The role of dynamic components of the original motive fluid into mechanical energy to the pressure that the hydraulic system of pumps, it is to power the entire hydraulic system. The structure of the form of hydra- ulic pump gears are generally pump, vane pump and piston pump.Implementation of components (such as hydraulic cylinders and hydraulic motors) which isthe pressure of the liquid can be converted to mechanical energy to drive the load for a straight line reciprocating movement or rotational movement.Control components (that is, the various hydraulic valves) in the hydraulic system to control and regulate the pressure of liquid, flow rate and direction. According to the different control functions, hydraulic pressure control valve can be divided into valves, flow control valves and directional control valve. Pressure control valves are divided into benefits flow valve (safety valve), pressure relief valve, sequence valve, pressure relays, etc.; flow control valves including throttle, adjusting the valves, flow diversion valve sets, etc.; directional control valve includes a one-way valve , one-way fluid control valve, shuttle valve, valve and so on. Under the control of different ways, can be divided into the hydraulic valve control switch valve, control valve and set the value of the ratio control valve.Auxiliary components, including fuel tanks, oil filters, tubing and pipe joints, seals, pressure gauge, oil level, such as oil dollars.Hydraulic oil in the hydraulic system is the work of the energy transfer medium, there are a variety of mineral oil, emulsion oil hydraulic molding Hop categories.The role of the hydraulic system is to help humanity work. Mainly by the implementation of components to rotate or pressure into a reciprocating motion.Hydraulic system and hydraulic power control signal is composed of two parts, the signal control of some parts of the hydraulic power used to drive the control valve movement.Part of the hydraulic power means that the circuit diagram used to show the differentfunctions of the interrelationship between components. Containing the source of hydraulic pump, hydraulic motor and auxiliary components; hydraulic control part contains a variety of control valves, used to control the flow of oil, pressure and direction; operative or hydraulic cylinder with hydraulic motors, according to the actual requirements of their choice.In the analysis and design of the actual task, the general block diagram shows the actual operation of equipment. Hollow arrow indicates the signal flow, while the solid arrows that energy flow.Basic hydraulic circuit of the action sequence - Control components (two four-way valve) and the spring to reset for the implementation of components (double-acting hydraulic cylinder), as well as the extending and retracting the relief valve opened and closed. For the implementation of components and control components, presentations are based on the corresponding circuit diagram symbols, it also introduced ready made circuit diagram symbols.Working principle of the system, you can turn on all circuits to code. If the first implementation of components numbered 0, the control components associated with the identifier is 1. Out with the implementation of components corresponding to the identifier for the even components, then retracting and implementation of components corresponding to the identifier for the odd components. Hydraulic circuit carried out not only to deal with numbers, but also to deal with the actual device ID, in order to detect system failures.DIN ISO1219-2 standard definition of the number of component composition, which includes the following four parts: device ID, circuit ID, component ID and component ID.The entire system if only one device, device number may be omitted.Practice, another way is to code all of the hydraulic system components for numbers at this time, components and component code should be consistent with the list of numbers. This method is particularly applicable to complex hydraulic control system, each control loop are the corresponding number with the systemWith mechanical transmission, electrical transmission compared to the hydraulic drive has the following advantages:1. a variety of hydraulic components can easily and flexibly to layout.2. light weight, small size, small inertia, fast response.3. to facilitate manipulation of control, enabling a wide range of stepless speed regulation (speed range of 2000:1).4. to achieve overload protection automatically.5. the general use of mineral oil as a working medium, the relative motion can be self-lubricating surface, long service life;6. it is easy to achieve linear motion .7. it is easy to achieve the automation of machines, when the joint control of the use of electro-hydraulic, not only can achieve a higher degree of process automation, and remote control can be achieved.The shortcomings of the hydraulic system:1. as a result of the resistance to fluid flow and leakage of the larger, so less efficient. If not handled properly, leakage is not only contaminated sites, but also may cause fire and explosion.2. vulnerable performance as a result of the impact of temperature change, it would be inappropriate in the high or low temperature conditions.3. the manufacture of precision hydraulic components require a higher, more expensive and hence the price.4. due to the leakage of liquid medium and the compressibility and can not be strictly the transmission ratio.5. hydraulic transmission is not easy to find out the reasons for failure; the use and maintenance requirements for a higher level of technology.In the hydraulic system and its system, the sealing device to prevent leakage of the work of media within and outside the dust and the intrusion of foreign bodies. Seals played the role of components, namely seals. Medium will result in leakage of waste, pollution and environmental machinery and even give rise to malfunctioning machinery and equipment for personal accident. Leakage within the hydraulic system will cause a sharp drop in volumetric efficiency, amounting to less than the required pressure, can not even work. Micro-invasive system of dust particles, can cause or exacerbate friction hydraulic component wear, and further lead to leakage.Therefore, seals and sealing device is an important hydraulic equipment components. The reliability of its work and life, is a measure of the hydraulic system an important indicator of good or bad. In addition to the closed space, are the use of seals, so that two adjacent coupling surface of the gap between the need to control the liquid can be sealed following the smallest gap. In the contact seal, pressed into self-seal-style and self-styled self-tight seal (ie, sealed lips) two.The three hydraulic system diseases1. as a result of heat transmission medium (hydraulic oil) in the flow velocity in various parts of the existence of different, resulting in the existence of a liquid within the internal friction of liquids and pipelines at the same time there is friction between the inner wall, which are a result of hydraulic the reasons for the oil temperature. Temperature will lead to increased internal and external leakage, reducing its mechanical efficiency. At the same time as a result of high temperature, hydraulic oil expansion will occur, resulting in increased com- pression, so that action can not be very good control of transmission. Solution: heat is the inherent characteristics of the hydraulic system, not only to minimize eradication. Use a good quality hydraulic oil, hydraulic piping arrangement should be avoided as far as possible the emergence of bend, the use of high-quality pipe and fittings, hydraulic valves, etc.2. the vibration of the vibration of the hydraulic system is also one of its malaise. As a result of hydraulic oil in the pipeline flow of high-speed impact and the control valve to open the closure of the impact of the process are the reasons for the vibration system. Strong vibration control action will cause the system to error, the system will also be some of the more sophisticated equipment error, resulting in system failures. Solutions: hydraulic pipe should be fixed to avoid sharp bends. To avoid frequent changes in flow direction, can not avoid damping measures should be doing a good job. The entire hydraulic system should have a good damping measures, while avoiding the external local oscillator on the system.3. the leakage of the hydraulic system leak into inside and outside the leakage. Leakagerefers to the process with the leak occurred in the system, such as hydraulic piston-cylinder on both sides of the leakage, the control valve spool and valve body, such as between the leakage. Although no internal leakage of hydra- ulic fluid loss, but due to leakage, the control of the established movements may be affected until the cause system failures. Outside means the occurrence of leakage in the system and the leakage between the external environment. Direct leakage of hydraulic oil into the environment, in addition to the system will affect the working environment, not enough pressure will cause the system to trigger a fault. Leakage into the environment of the hydraulic oil was also the danger of fire. Solution: the use of better quality seals to improve the machining accuracy of equipment.Another: the hydraulic system for the three diseases, it was summed up: "fever, with a father拉稀" (This is the summary of the northeast people). Hydraulic system for the lifts, excavators, pumping station, dynamic, crane, and so on large-scale industry, construction, factories, enterprises, as well as elevators, lifting platforms, Deng Axle industry and so on.Hydraulic components will be high-performance, high-quality, high reliability, the system sets the direction of development; to the low power, low noise, vibration, without leakage, as well as pollution control, water-based media applications to adapt to environmental requirements, such as the direction of development; the development of highly integrated high power density, intelligence, macaronis and micro-light mini-hydraulic components; active use of new techniques, new materials and electronics, sensing and other high-tech.---- Hydraulic coupling to high-speed high-power and integrated development of hydraulic transmission equipment, development of water hydraulic coupling medium speedand the field of automotive applications to develop hydraulic reducer, improve product reliability and working hours MTBF; hydraulic torque converter to the development of high-power products, parts and components to improve the manufacturing process technology to improve reliability, promote computer-aided technology, the development of hydraulic torque converter and power shift transmission technology supporting the use of ; Clutch fluid viscosity should increase the quality of products, the formation of bulk to the high-power and high-speed direction.Pneumatic Industry:---- Products to small size, light weight, low power consumption, integrated portfolio of development, the implementation of the various types of components, compact structure, high positioning accuracy of the direction of development; pneumatic components and electronic technology, to the intelligent direction of development; component performance to high-speed, high-frequency, high-response, high-life, high temp- erature, high voltage direction, commonly used oil-free lubrication, application of new technology, new technology and new materials.1. Used high-pressure hydraulic components and the pressure of continuous work to reach 40Mpa, the maximum pressure to achieve instant 48Mpa;2. Diversification of regulation and control;3. To further improve the regulation performance, increase the efficiency of the power train;4. Development and mechanical, hydraulic, power transmission of the composite portfolio adjustment gear;5. Development of energy saving, energy efficient system function;6. To further reduce the noise;7. Application of Hydraulic Cartridge Valves thread technology, compact structure, to reduce the oil spill.液压系统液压传动和气压传动称为流体传动，是根据17世纪帕斯卡提出的液体静压力传动原理而发展起来的一门新兴技术，1795年英国约瑟夫•布拉曼(Joseph Braman,1749-1814)，在伦敦用水作为工作介质，以水压机的形式将其应用于工业上，诞生了世界上第一台水压机。
中英文文献翻译-液压制动系统
附录AHydraulic Brake SystemsWhen you step on the brake pedal,you expect the vehicle to stop.The brake pedal operates a hydraulic that is used for two reasons.First,fluid under pressure can be carried to all parts of the vehicle by small hoses or metal lines without taking up a lot of room of causing routing problems.Second,the hydraulic fluid offers a great mechanical advantage-little foot pressure is required on the pedal,but a great deal of pressure is generated at the wheels.The brake pedal is linked to a piston in the brake master cylinder containing a small piston and a fluid reservoir.Modern master cylinders are actually two separate cylinders.Such a system is called a dual circuit,because the front cylinder is connected to the front brakes and the rear cylinder to the rear brakes.(Some vehicles are connected diagonally).The two cylinders are actually separated,allowing for emergency stopping power should one part of the system fail.The entire hydraulic system from the master cylinder to the wheels is full of hydraulic brake fluid.When the brake pedal is depressed,the piston in the master cylinder are forced to move,exerting tremendous force on the fluid in the lines.The fluid has nowhere to go,and forces the wheel cylinder pistons(drum brakes) orcaliper pistons(disc brakes) to exert pressure on the brake shoes or pads.The friction between the brake shoe and wheel drum or the brake pad and rotor (disc) slows the vehiche and eventually stops it.Also attached to the brake pedal si a switch that lights the brake lights as the pedal is depressed.The lights stay on until the brake pedal is released and returns to its normal position.Each wheel cylinder in a drum brake system contains two pistons,one at either end,which push outward in opposite directions.In disc brake systems,the wheel cylinders are part of the caliper (there can be as many as four or as few as one ).Whether disc or drum type,all pistons use some type of rubber seal to prevent leakage around thepiston,and a rubber dust boot seals the outer of the wheel cylinders against dirt and moisture.When the brake pedal is released,a spring pushes the master cylinder pistons back to their normal positions.Check valves in the master cylinder piston allow fluid to flow toward the wheel cylinders or calipers as the piston returns.Then as the brake shoe return springs pull the brake shoes back to the released position,excess fluid returns to the master cylinder through compensating ports,which have been uncovered as the pistons move back.Any fluid that has leaked from the system will also be replaced through the compensating ports.All dual circuit brake systems use a switch to activate a light,warning of brake failure.The switch si located in a valve mounted near the master cylinder.A piston in the valve reveives pressure on each end from the front and rear brake circuits.When the pressures are balanced,the piston remains stationary,but when one circuit has a leak,greater pressure during the application of the brakes will force the piston to one side or the other,closing the switch and activating the warning light.The light can also be activated by the ignition switch during engine starting or by the parking brake.Front disc,rear drum brake systems also have a metering valve to prevent the front disc brakes from engaging before the rear brakes have contacted the drums.This ensures that the front brakes will not normally be used alone to stop the vehicle.A proportioning valve is also used to limit pressure to the rear brakes to prevent rear wheel lock-up during hard braking.Brake shoes and pads are constructed in a similar.The pad or shoe is composed of a metal backing plate and a priction lining.The lining is either bonded(glued) to the metal,or riveted.Generally,riveted linings provide superior performance,but good quality bonded linings are perfectly adequate.Friction materials will vary between manufacturers and type of pad and the material compound may be referred to as asbestos,organic,semi-metallic,metallic.The difference between these compounds lies in the types and percentages of friction materials used,material binders and performance modifiers.Generally speaking,organic and non-metallic asbestos compound brakes are quiet,easy on rotors and provide good feel.But this comes at the expense of high temperature operation,so they may not be your best choice for heavy duty use or mountiandriving.In most cases,these linings will wear somewhat faster than metallic compound pads,so you will usually replace them more often.But,when using these pads,rotors tend to last longer.Semi-metallic or metallic compound brake linings will vary in performance based on the metallic contents of the compound.Again,generally speaking,the higher the metallic content,the better the friction material will resist heat.This makes them more appropriate for heavy duty applications,but at the expense of braking performance before the pad reaches operating temperature.The first few applications on a cold morning may not give strong braking.Also,metallics and semi-metallics are more likely to squeal,In most cases,metallic compounds last longer than non-metallic pads,but they tend to cause more wear on the rotors.If you use metallic pads,expect to replace the rotors more often.When deciding what type of brake lining is right for you,keep in mind that today’s modern cars have brake materials which are matched to the expected vehicle’s performance capabilities.Changing the material from OEM specification could adversely addect brake feel or responsiveness.Before changing the brake materials,talk to your deaker or parts supplier to help decide what is most appropriate for your application. Remenber that use applications such as towing,stop and go driving,driving down mountain roads,and racing may require a change to a higher performance material.Some more exotic materials are also used in brake linings,among which are Kevlar and carbon compounds.These materials have the capability of extremely good performance for towing,mountain driving or racing.Wear characteristics can be similar to either applications tend to wear like metallic linings,while many of the streetapplications aremore like the non-metallics.附录B液压制动系统当踩下制动踏板，您希望该车辆停下。
机械外文翻译文献翻译液压系统1
外文原文：Theory of fluid propertiesWe will concentrate mainly on three fluid properties in this chapter:• The density which leads to mass and hence to hydraulic inertia effects.• The viscosity which leads to the hydraulic friction effects.• The compressi bility and thus the bulk modulus which leads to the hydraulic system stiffness. Notice that the compressibility effect can be modified by air release, cavitation phenomena and by expansion of a pipe, hose or chamber containing the hydraulic fluid.1 Density and compressibility coefficientThe density is the mass of a substance per unit volume:Density has dimensions of [M/L3] and is expressed in kilograms per cubic meter [kg/m3]. As mentioned previously the density is a function of the pressure and the temperature:This function can be approximated by the first three terms of a Taylor series:This can also be expressed as:WithAndThis equation is the linearized state equation for a liquid. Using the definition of thedensity, the two coefficients α and B can also be expressed as:B is known as the isothermal bulk modulus or for simplicity the bulk modulus and α is known as the cubical expansion coefficient. Since fluid density varies with the applied pressure, this implies that a given mass of fluid submitted to a pressure change changes its volume. This phenomenon leads to the definition of the compressibility coefficient β:where β is expressed in units Pa 1 (or m2/N). Considering the relation for a closed hydraulic circuit the mass is constant, and hence:it follows thatUsing the definition of the compressibility coefficient β we obtain:More usually we use the bulk modulus B also known as the volumetric elasticity modulus:The relation between ρ and B implies mass conservation. This relation must be RIGOROUSLY RESPECTED in the calculations. In the modeling and simulation context of fluid energy systems, disregarding the relation between ρ and B leads to abnormal evolutions of pressure in the closed circuit submitted to compression and expansion cycles. This phenomenon is strongly accentuated if aeration occurs in the circuit (when dissolved air in the fluid reappears in the form of bubbles). We shall approach this point by examining the phenomena of aeration and cavitation. The aircan also have adverse consequences on a fluid compressibility. In liquid air can be present in two forms: entrapped and dissolved.Entrapped airWhen the return pipe is not submersed in the tank the liquid jet can entrain some air bubbles in the tank. Another phenomenon that affects the quantity of air in liquid is the leakage.Figure 1: Liquid leakageFigure 2: Air is entrainedThis air stays in the liquid as cavities and can modify the fluid compressibility. In this context we talk about effective bulk modulus. Figure 3 shows the bulk modulus of a diesel fuel at 40 °C with 0, 0.01, 0.1, 1, 10% air. The plot is obtained using the system shown. The model of the diesel fuel properties is based on accurate ex-perimental measurements and are designed for use with injection system which are very fast acting. For this reason air is assumed to be entrained rather than dissolved.Figure 3Dissolved airAir can also be dissolved in a liquid. A certain amount of air molecule can be part of the liquid. In this case the dissolved air does not significantly change the fluid properties.2 Air release and cavitationAir can be dissolved or entrained in liquids and it is possible for air to change from one of these two forms to the other depending on the conditions to which the fluid is subjected.Suppose the fluid is in equilibrium with a certain percentage of dissolved gas (usually air: nitrogen and oxygen). Lowering the pressure above a critical value called the saturation pressure induces aeration. This is the process where the dissolved gas forms air bubbles in the liquid until all the dissolved gases or air are free.The exact point where all the dissolved gas has come out of solution is difficult to pin-point because it depends on the chemical composition and behavior of the gas. This is a non-symmetrical dynamic process: the growing process does not have the same dynamics as when air bubbles disappear. In consequence the total amount of bubbles created when the pressure drops may or may not be redissolved in the liquid when it rises again.If the pressure is dropped further and above another critical value called the vapor pres s ure, the fluid itself starts to vaporize. It corresponds to a liquid phase change. At some point only fluid vapor and gas exist. In liquid systems the term cavitation usually refers to the formation and collapse of cavities in the liquid even if cavities contain air or liquid vapor.To summarize with a sketch what we have introduced see above:Figure 4: Air release and cavitationThe development of a cavity is now recognized as being associated with a nucleation center such as microscopic gas particles, wear or wall asperities. When the liquid is subjected to a tensile stress, cavities do not form as a result of liquid rupture but are caused by the rapid growth of these nuclei.To understand this, think of beer (or champagne if you prefer) in a bottle, when it is closed you see no air bubbles and the liquid does not look fizzy. The pressure in the bottle is above the saturation pressure of the gas in the liquid. When you open the bottle suddenly bubbles appear and so the dissolved gas (molecules of gas held in the liquid) starts to appear as gas.In fact the liquid is gas saturated and the atmospheric pressure is less than the saturation pressure of the liquid. This phenomenon is clearly not cavitation but air release (aeration). Considering nuclei effects, bubbles form only at particular places in your glass: around the glass (due to small asperities) and round any particles present in the liquid. Theoretically, if your liquid was perfectly pure and the wall of the system perfectly regular, air release or cavitation would occur with great difficulty! The key point about cavitation is that it is a phase change: the liquid changes to vapor.A comparison can be made between cavitation and boiling. If we look at the phasediagram below:Figure 5: Cavitation and boilingBoiling is a phase change at constant pressure and variable temperature and cavitation is a phase change at constant temperature and variable pressure.In any system air release starts first and if the pressure decreases further, cavitation may occur. This means that, sometimes, people talk about cavitation when the real phenomenon is air release. Both phenomena can lead to destruction of the material or component.In both cases it is entrained gas that causes the troubles. When cavities encounter high pressure in the downstream circuit, these bubbles or cavities can be unstable and can collapse implosively. The pressure developed at collapse can be large enough to cause severe mechanical damage in the containing vessel. It is well-known that hydraulic pumps and pipework can be badly damaged by cavitaton and air release.In all classical hydraulic systems air release and cavitation must be avoided to prevent material destruction but sometimes it is required like for injection systems to prepare the spray formation.3 ViscosityViscosity is a measure of the resistance of the fluid to flow. This characteristic has both positive and negative effects on fluid power systems. A low viscosity leads to oil leaks in the dead zone formed between the mechanical parts in movement, and a high viscosity will lead to loss of pressure in hydraulic ducts.Viscosity is a characteristic of liquids and gases and is manifested in motion throughinternal damping. Viscosity results from an exchange of momentum by molecular diffusion between two layers of fluid with different velocities. In this sense, the viscosity is a fluid property and not a flow property.Figure 6: ViscosityFigure 6 shows the relation between shearing constraint and difference of flow velocity between two layers .The definition of viscosity was first given by Newton. Between two layers of distance dy, the exerted force between these two layers is given by:where U(y) is the velocity depending on the radial position y and dU/dy the velocity gradient. This proportionality expresses the notion of Newtonian fluid and allows the introduction of μ defined as the dynamic viscosity or the absolute viscosity.The dimension of μ is [ML1-T 1-] and the SI unit is kg/m/s or Pa s. The older unit is the Poise, P, which is 0.1 kg/m/s. However, this is very small and hence the milli Poise, mP, is the common unit which is 10-4 kg/m/s.The dynamic viscosity is the constant of proportionality between a stress and the intensity of shearing between two neighboring layers:However the absolute viscosity is not very often used in fundamental equations. For example the dynamics of the elementary volume between the two layers is expressedas:and thus using the shear stress calculation:In other formulas (e.g. Navier Stokes) the ratio between the absolute viscosity and the density occurs so often that a new parameter called the kinematic viscosity ν is introduced .of dimension [L2T 1-] and so the SI unit is the m2/s. The older unit of kinematic viscosity is the Stoke, St, which is 104-m2/s. However, even this is a very small unit and hence the centistoke cSt is the common unit with 1 cSt = 106-m2/s. This parameter is easily measured with viscometers.Note that the viscosity varies significantly with the fluid temperature.Figure 7: Viscosity against temperatureNormally in absence of air release and cavitation the variation with pressure is not great unless the pressure is very extreme.Figure 8: Variation with pressureViscosity influence on the flowAnother important aspect of the viscosity is its influence on the flow conditions of the fluid. We can distinguish two types of flow conditions:• Laminar flow for which the flow lines are parallel and shearing forces create a pressure drop.• Turbulent flow for which the fluid particles have a disordered, random movement leading to a loss of pressure.These two conditions can be distinguished using the Reynolds number which is defined as follows:WithU: average fluid velocityd: diameter of the duct (hydraulic diameter for others geometries)ρ: densityμ: dynamic viscosityν: kinematic viscosityThe transition between laminar to turbulent flow occurs at the critical Reynolds number. This is not well defined, there exists always a transition region. In a hydraulic line, the critical Reynolds number is generally between 1500 to 2000. For uneven geometries (thin-walled orifices), the critical Reynolds number can be lower than 100. For non-circular cross sections, the hydraulic diameter can be used to determine the Reynolds number. Hydraulic diameter is defined as follows:We now give one example:• Circular orifice of diameter:Flow through orificesOrifices (also called restrictions) can be fixed or variable and occur in huge numbers in fluid systems. Not surprisingly in Engineering courses a mathematical description is presented. This is usually based on Bernoulli’s equation and leads to the formwhere Cq is the flow coefficient. This is variously described as typically 0.7 or varying with orifice geometry and Reynolds number.The second alternative is obviously more correct. If we do take a constant value, we are forced to have the gradient of Q against infinity at the origin! This cannot be and if you try to implement it is a numerical disaster! Clearly the flow is laminar for sufficiently small pressure drops which means that Cq is certainly not constant. One solution is to perform detailed e xperiments and compute Cq against Reynold’s number. In the context of the orifice (not necessarily circular) the Reynold’s number iswhere U is a mean velocity and dh the hydraulic diameter. If we take U=Q/A, we end up with the form Cq =f(Q) and ultimately withIt is possible to work with an implicit relationship like this but we would prefer an explicit formula.This is provided by introducing another dimensionless number known as the flow number and denoted by λ. This is defined asFrom a modelin g point of view λ contains quantities we know. Using λ we haveand provided we have,we have an explicit relationship which is easy to evaluate. There are no more problems to obtain measurements forthan forand so the flow number form has many advantages.References ：[1] McCloy D, Discharge Characteristics of Servo Valve Orifices, 1968 Fluid International Conference.[2] R.C. Binder, “Fluid Mechanics”. 3rd Edition, 3rd Printing. Prentice-Hall, Inc., Englewood Cliffs,NJ. 1956.译文：液压油理论我们将在本章主要讨论液压油的三个特性：•密度（使油液具有质量和液感效应）；•粘性（使油液具有液阻效应）；•可压缩性和体积弹性模量（使油液具有容性效应），值得提醒的是容性效应会受油液中析出的空气、气穴现象和装有油液的的管道、软管或油腔的影响。
液压系统外文文献翻译中英文
外文文献翻译(含：英文原文及中文译文)英文原文Hydraulic systemW Arnold1 IntroductionThe hydraulic station is called a hydraulic pump station and is an independent hydraulic device. It is step by step to supply oil. And control the direction of hydraulic oil flow, pressure and flow, suitable for the host and hydraulic equipment can be separated on the various hydraulic machinery.After the purchase, the user only needs to connect the hydraulic station and the actuator (hydraulic or oil motor) on the mainframe with different tubings. The hydraulic machine can realize various specified actions and working cycles.The hydraulic station is a combination of manifolds, pump units or valve assemblies, electrical boxes, and tank electrical boxes. Each part function is:The pump unit is equipped with a motor and an oil pump, which is the power source of the hydraulic station and can convert mechanical energy into hydraulic oil pressure energy.V alve combination - its plate valve is mounted on the vertical plate, and the rear plate is connected with the same function as the manifold.Oil manifolds - assembled from hydraulic valves and channel bodies. It regulates hydraulic oil pressure, direction and flow.Box--a semi-closed container for plate welding. It is also equipped with an oil screen, an air filter, etc., which is used for cooling and filtering of oil and oil.Electrical box - divided into two types: one is to set the external lead terminal board; one is equipped with a full set of control appliances.The working principle of the hydraulic station: The motor drives the oil pump to rotate, then the pump sucks oil from the oil tank and supplies oil, converts the mechanical energy into hydraulic pressure energy, and the hydraulic oil passes through the manifold (or valve assembly) to adjust the direction, pressure and flow and then passes through the external tube. The way to the hydraulic cylinder or oil motor in the hydraulic machinery, so as to control the direction of the hydraulic motor, the strength of the speed and speed, to promote all kinds of hydraulic machinery to do work.(1) Development history of hydraulic pressureThe development history of hydraulics (including hydraulic power, the same below), pneumatics, and seals industry in China can be roughly divided into three stages, namely: the starting stage in the early 1950s to the early 60s; and the professional in the 60s and 70s. The growth stage of the production system; the 80-90's is a stage of rapid development. Among them, the hydraulic industry began in the early 1950s with thedevelopment of hydraulic machines such as Grinding Machines, broaching machines, and profiling lathes, which were produced by the machine tool industry. The hydraulic components were produced by the hydraulic workshop in the machine tool factory, and were produced for self use. After entering the 1960s, the application of hydraulic technology was gradually promoted from the machine tool to the agricultural machinery and engineering machinery. The original hydraulic workshop attached to the main engine plant was independent and became a professional manufacturer of hydraulic components. In the late 1960s and early 1970s, with the continuous development of mechanization of production, particularly in the provision of highly efficient and automated equipment for the second automobile manufacturing plant, the hydraulic component manufacturing industry witnessed rapid development. The batch of small and medium-sized enterprises also began to become specialized manufacturers of hydraulic parts. In 1968, the annual output of hydraulic components in China was close to 200,000 pieces. In 1973, in the fields of machine tools, agricultural machinery, construction machinery and other industries, the professional factory for the production of hydraulic parts has grown to over 100, and its annual output exceeds 1 million pieces. Such an independent hydraulic component manufacturing industry has taken shape. At this time, the hydraulic product has evolved from the original imitation Su product intoa combination of imported technology and self-designed products. The pressure has been developed towards medium and high pressures, and electro-hydraulic servo valves and systems have been developed. The application of hydraulics has been further expanded. The pneumatic industry started a few years later than hydraulics, and it was only in 1967 that it began to establish a professional pneumatic components factory. Pneumatic components began to be manufactured and sold as commodities. Its sealing industry including rubber seals, flexible graphite seals, and mechanical seals started from the production of common O-rings, oil seals, and other extruded rubber seals and asbestos seal products in the early 1950s. In the early 1960s, it began to develop and produce flexible products. Graphite seals and mechanical seals and other products. In the 1970s, a batch of batches of professional production plants began to be established one after another in the systems of the former Ministry of Combustion, the Ministry of Agriculture, and the Ministry of Agricultural Machinery, formally forming the industry, which laid the foundation for the development of the seal industry.In the 1980s, under the guidance of the national policy of reform and opening up, with the continuous development of the machinery industry, the contradiction between the basic components lags behind the host computer has become increasingly prominent and caused the attention of all relevant departments. To this end, the former Ministry of Machinesestablished the General Infrastructure Industry Bureau in 1982, and unified the original pneumatic, hydraulic, and seal specialties that were scattered in the industries of machine tools, agricultural machinery, and construction machinery, etc. The management of a piece of office, so that the industry in the planning, investment, the introduction of technology and scientific research and development and other aspects of the basic parts of the bureau's guidance and support. This has entered a period of rapid development, it has introduced more than 60 foreign advanced technology, of which more than 40 hydraulic, pneumatic 7, after digestion and absorption and technological transformation, are now mass production, and has become the industry's leading products . In recent years, the industry has intensified its technological transformation. From 1991 to 1998, the total investment of national, local, and corporate self-raised funds totaled about 2 billion yuan, of which more than 1.6 billion were hydraulic. After continuous technological transformation and technological breakthroughs, the technical level of a group of major enterprises has been further improved, and technological equipment has also been greatly improved, laying a good foundation for forming a high starting point, specialization, and mass production. In recent years, under the guidance of the principle of common development of multiple ownership systems in the country, various small and medium-sized enterprises with different ownership have rapidly emerged and haveshown great vitality. With the further opening up of the country, foreign-funded enterprises have developed rapidly, which plays an important role in raising industry standards and expanding exports. So far China has established joint ventures with famous manufacturers in the United States, Germany, Japan and other countries or directly established piston pumps/motors, planetary speed reducers, hydraulic control valves, steering gears, hydraulic systems, hydrostatic transmissions, and hydraulic components. The company has more than 50 manufacturing enterprises such as castings, pneumatic control valves, cylinders, gas processing triplets, rubber seals, and mechanical seals, and has attracted more than 200 million U.S. dollars in foreign capital.(2) Current statusBasic profileAfter more than 40 years of hard work, China's hydraulics, pneumatics and seals industry has formed a complete industrial system with a certain level of production capacity and technical level. According to the statistics of the third n ational industrial census in 1995, China’s state-owned, privately-owned, cooperative, village-run, individual, and “funded enterprises” have annual sales income of more than 1 million yuan in hydraulic, pneumatic, and seal industrial townships and above. There are a total of more than 1,300 companies, including about 700 hydraulics, and about 300 pneumatic and sealing parts. According to thestatistics of the international industry in 1996, the total output value of the hydraulic industry in China was about 2.448 billion yuan, accounting for the 6th in the world; the total output value of the pneumatic industry was about 419 million yuan, accounting for the world’s10 people.2. Current supply and demand profileWith the introduction of technology, independent development and technological transformation, the technical level of the first batch of high-pressure plunger pumps, vane pumps, gear pumps, general hydraulic valves, oil cylinders, oil-free pneumatic components and various types of seals has become remarkable. Improve, and can be stable mass production, provide guarantees for all types of host to improve product quality. In addition, certain achievements have also been made in the aspects of CAD, pollution control, and proportional servo technology for hydraulic pneumatic components and systems, and have been used for production. So far, the hydraulic, pneumatic and seal products have a total of about 3,000 varieties and more than 23,000 specifications. Among them, there are about 1,200 types of hydraulic pressure, more than 10,000 specifications (including 60 types of hydrodynamic products, 500 specifications); about 1350 types of pneumatic, more than 8,000 specifications; there are also 350 types of rubber seals, more than 5000 The specifications are now basically able to adapt to the general needs ofvarious types of mainframe products. The matching rate for major equipment sets can reach more than 60%, and a small amount of exports has started.In 1998, the domestic production of hydraulic components was 4.8 million pieces, with sales of about 2.8 billion yuan (of which mechanical systems accounted for 70%); output of pneumatic components was 3.6 million pieces, and sales were about 550 million yuan (including mechanical systems accounting for about 60%) The production of seals is about 800 million pieces, and the sales volume is about 1 billion yuan (including about 50% of mechanical systems). According to the statistics of the annual report of the China Hydraulic and Pneumatic Sealing Industry Association in 1998, the production and sales rate of hydraulic products was 97.5% (101% of hydraulic power), 95.9% of air pressure, and 98.7% of seal. This fully reflects the basic convergence of production and sales.Although China's hydraulic, pneumatic and sealing industries have made great progress, there are still many gaps compared with the development needs of the mainframe and the world's advanced level, which are mainly reflected in the variety, performance and reliability of products. . Take hydraulic products as an example, the product varieties are only 1/3 of the foreign country, and the life expectancy is 1/2 of that of foreign countries. In order to meet the needs of key hosts, imported hosts, and majortechnical equipment, China has a large number of imported hydraulic, pneumatic, and sealing products every year. According to customs statistics and relevant data analysis, in 1998, the import volume of hydraulic, pneumatic and seal products was about 200 million U.S. dollars, of which the hydraulic pressure was about 140 million U.S. dollars, the pneumatics were 30 million U.S. dollars, and the seal was about 0.3 billion U.S. dollars. The year is slightly lower. In terms of amount, the current domestic market share of imported products is about 30%. In 1998, the total demand for hydraulic parts in the domestic market was about 6 million pieces, and the total sales volume was 4 billion yuan; the total demand for pneumatic parts was about 5 million pieces, and the total sales volume was over 700 million yuan; the total demand for seals was about 1.1 billion yuan. Pieces, total sales of about 1.3 billion yuan. (3) Future developments1. The main factors affecting development(1) The company's product development capability is not strong, and the level and speed of technology development can not fully meet the current needs for advanced mainframe products, major technical equipment and imported equipment and maintenance;(2) Many companies have lagged behind in manufacturing process, equipment level and management level, and their sense of quality is not strong, resulting in low level of product performance, unstable quality,poor reliability, and insufficiency of service, and lack of user satisfaction. And trusted branded products;(3) The degree of professional specialization in the industry is low, the power is scattered, the duplication of the low level is serious, the product convergence between the region and the enterprise leads to blind competition, and the prices are reduced each other, thus the efficiency of the enterprise is reduced, the funds are lacking, and the turnover is difficult. Insufficient investment in development and technological transformation has severely restricted the overall level of the industry and its competitive strength.(4) When the degree of internationalization of the domestic market is increasing, foreign companies have gradually entered the Chinese market to participate in competition, coupled with the rise of domestic private, cooperative, foreign-funded, and individual enterprises, resulting in increasing impact on state-owned enterprises. .2. Development trendWith the continuous deepening of the socialist market economy, the relationship between supply and demand in the hydraulic, pneumatic and sealed products has undergone major changes. The seller market characterized by “shortage” has basically become a buyer’s market characterized by “structured surplus”. Replaced by. From the perspective of overall capacity, it is already in a trend of oversupply, and in particular,general low-grade hydraulic, pneumatic and seals are generally oversupply; and like high-tech products with high technological content and high value and high value-added products that are urgently needed by the host, Can not meet the needs of the market, can only rely on imports. After China's entry into the WTO, its impact may be greater. Therefore, during the “10th Five-Y ear Plan” period, the growth of the industry’s output value must not only rely on the growth of quantity. Instead, it should focus on the structural contradiction of the industry and intensify efforts to adjust the industrial structure and product structure. It should be based on the improvement of quality. Product technology upgrades in order to adapt to and stimulate market demand, and seek greater development.2. Hydraulic application on power slide(1) Introduction of Power Sliding TableUsing the binding force curve diagram and the state space analysis method to analyze and study the sliding effect and the smoothness of the sliding table of the combined machine tool, the dynamics of the hydraulic drive system of the sliding table—the self-regulating back pressure regulating system are established. mathematical model. Through the digital simulation system of the computer, the causes and main influencing factors of the slide impact and the motion instability are analyzed. What kind of conclusions can be drawn from those, if we canreasonably design the structural dimensions of hydraulic cylinders and self-regulating back pressure regulators ——The symbols used in the text are as follows:s 1 - flow source, that is, the flow rate of the governor valve outlet;S el —— sliding friction of the sliding table;R - the equivalent viscous friction coefficient of the slide;I 1 - quality of slides and cylinders;12 - self-adjusting back pressure valve core quality;C 1, c 2 - liquid volume without cylinder chamber and rod chamber;C 2 - Self-adjusting back pressure valve spring compliance;R 1, R2 - Self-adjusting back pressure valve damping orifice fluid resistance;R 9 - Self-adjusting back pressure valve valve fluid resistance;S e2——initial pre-tightening force of self-adjusting back pressure valve spring;I 4, I5 - Equivalent liquid sense of the pipeline;C 5, C 6 - equivalent liquid capacity of the pipeline;R 5, R7 - Equivalent liquid resistance of the pipeline;V 3, V4 - cylinder rodless cavity and rod cavity volume;P 3, P4—pressure of the rodless cavity and rod cavity of the cylinder;F - the slide bears the load;V - speed of slide motion;In this paper, the power bond diagram and the state space splitting method are used to establish the system's motion mathematical model, and the dynamic characteristics of the slide table can be significantly improved.In the normal operation of the combined machine tool, the magnitude of the speed of the slide, its direction and the load changes it undergoes will affect its performance in varying degrees. Especially in the process of work-in-process, the unsteady movement caused by the advancing of the load on the slide table and the cyclical change of the load will affect the surface quality of the workpiece to be machined. In severe cases, the tool will break. According to the requirements of the Dalian Machine Tool Plant, the author used the binding force curve diagram and the state space analysis method to establish a dynamic mathematical model of a self-adjusting back pressure and speed adjustment system for the new hydraulic drive system of the combined machine tool slide. In order to improve the dynamic characteristics of the sliding table, it is necessary to analyze the causes and main influencing factors of the impetus and movement of the sliding table. However, it must pass the computer's digital simulation and the final results obtained from the research.(2) Dynamic Mathematical ModelThe working principle diagram of the self-adjusting back pressure speedregulation system of the combined machine tool slide hydraulic drive system is shown in the figure. This system is used to complete the work-cycle-stop-rewind. When the sliding table is working, the three-position four-way reversing valve is in the illustrated position. The oil supply pressure of the oil pump will remain approximately constant under the effective action of the overflow valve, and the oil flow passes through the reversing valve and adjusts the speed. The valve enters the rodless chamber of the cylinder to push the slide forward. At the same time, the pressurized oil discharged from the rod chamber of the cylinder will flow back to the tank through the self-regulating back pressure valve and the reversing valve. During this process, there was no change in the operating status of both the one-way valve and the relief valve. The complex and nonlinear system of the hydraulic drive system of the self-adjusting back pressure governor system is a kind of self-adjusting back-pressure governor system. To facilitate the study of its dynamic characteristics, a simple and reasonable dynamic mathematical model that only considers the main influencing factors is established. Especially important [1][2]. From the theoretical analysis and the experimental study, we can see that the system process time is much longer than the process time of the speed control valve. When the effective pressure bearing area of the rodless cavity of the fuel tank is large, the flow rate at the outlet of the speed control valve is instantaneous. The overshoot is reflected in thesmall change in speed of the slide motion [2]. In order to further broaden and deeply study the dynamic characteristics of the system so that the research work can be effectively performed on a miniature computer, this article will further simplify the original model [2], assuming that the speed control valve is output during the entire system pass. When the flow is constant, this is considered to be the source of the flow. The schematic diagram of the dynamic model structure of this system is shown in Fig. 2. It consists of a cylinder, a sliding table, a self-adjusting back pressure valve, and a connecting pipe.The power bond graph is a power flow graph. It is based on the transmission mode of the system energy, based on the actual structure, and uses the centralized parameters to represent the role of the subsystems abstractly as a resistive element R, a perceptual element I, and a capacitive element. Three kinds of role of C. Using this method, the physical concept of modeling is clear, and combined with the state-space analysis method, the linear system can be described and analyzed more accurately. This method is an effective method to study the dynamic characteristics of complex nonlinear systems in the time domain. According to the main characteristics of each component of the self-adjusting back pressure control system and the modeling rules [1], the power bond diagram of the system is obtained. The upper half of each key in the figure represents the power flow. The two variables that makeup the power are the force variables (oil pressure P and force F) and the flow variables (flow q and velocity v). The O node indicates that the system is connected in parallel, and the force variables on each key are equal and the sum of the flow variables is zero; 1 The nodes represent the series connection in the system, the flow variables on each key are equal and the sum of the force variables is Zero. TF denotes a transformer between different energy forms. The TF subscripted letter represents the conversion ratio of the flow variable or the force variable. The short bar on the key indicates the causal relationship between the two variables on the key. The full arrow indicates the control relationship. There are integral or differential relationships between the force and flow variables of the capacitive and perceptual elements in the three types of action elements. Therefore, a complex nonlinear equation of state with nine state variables can be derived from Fig. 3 . In this paper, the research on the dynamic characteristics of the sliding table starts from the two aspects of the slide's hedging and the smoothness of the motion. The fourth-order fixed-length Runge-Kutta is used for digital simulation on the IBM-PC microcomputer.(3) Slide advanceThe swaying phenomenon of the slide table is caused by the sudden disappearance of the load acting on the slide table (such as drilling work conditions). In this process, the table load F, the moving speed V, and thepressure in the two chambers of the cylinder P3 and P4 can be seen from the simulation results in Fig. 4. When the sliding table moves at a uniform speed under the load, the oil pressure in the rodless cavity of the oil cylinder is high, and a large amount of energy is accumulated in the oil. When the load suddenly disappears, the oil pressure of the cavity is rapidly reduced, and the oil is rapidly reduced. When the high-pressure state is transferred to the low-pressure state, a lot of energy is released to the system, resulting in a high-speed forward impact of the slide. However, the front slide of the sliding table causes the pressure in the rod cavity of the oil cylinder to cause the back pressure to rise, thereby consuming part of the energy in the system, which has a certain effect on the kicking of the slide table. We should see that in the studied system, the inlet pressure of the self-adjusting back pressure valve is subject to the comprehensive effect of the two-chamber oil pressure of the oil cylinder. When the load suddenly disappears, the pressure of the self-adjusting back pressure valve rapidly rises and stably exceeds the initial back pressure value. It can be seen from the figure that self-adjusting back pressure in the speed control system when the load disappears, the back pressure of the cylinder rises more than the traditional speed control system, so the oil in the rod cavity of the cylinder absorbs more energy, resulting in the amount of forward momentum of the slide It will be about 20% smaller than traditionalspeed control systems. It can be seen from this that the use of self-adjusting back-gear speed control system as a drive system slider has good characteristics in suppressing the forward punch, in which the self-adjusting back pressure valve plays a very large role.(4) The smoothness of the slideWhen the load acting on the slide changes periodically (such as in the case of milling), the speed of the slide will have to fluctuate. In order to ensure the processing quality requirements, it must reduce its speed fluctuation range as much as possible. From the perspective of the convenience of the discussion of the problem, assume that the load changes according to a sine wave law, and the resulting digital simulation results are shown in Figure 5. From this we can see that this system has the same variation rules and very close numerical values as the conventional speed control system. The reason is that when the change of the load is not large, the pressure in the two chambers of the fuel tank will not have a large change, which will eventually lead to the self-regulating back pressure valve not showing its effect clearly.(5) Improvement measuresThe results of the research show that the dynamic performance of a sliding table with self-regulating back pressure control system as a drive system is better than that of a traditional speed control system. To reduce the amount of kick in the slide, it is necessary to rapidly increase the backpressure of the rod cavity when the load disappears. To increase the smoothness of the sliding table, it is necessary to increase the rigidity of the system. The main measure is to reduce the volume of oil. From the system structure, it is known that the cylinder has a large volume between the rod cavity and the oil discharge pipe, as shown in Fig. 6a. Its existence in terms of delay and attenuation of the self-regulating back pressure valve function, on the other hand, also reduces the rigidity of the system, it will limit the further improvement of the propulsion characteristics and the smoothness of the motion. Thus, improving the dynamic characteristics of the sliding table can be handled by two methods: changing the cylinder volume or changing the size of the self-regulating back pressure valve. Through the simulation calculation of the structural parameters of the system and the comparison of the results, it can be concluded that the ratio of the volume V4 between the rod cavity and the oil discharge pipe to the volume V3 between the rodless cavity and the oil inlet pipe is changed from 5.5 to 5.5. At 1 oclock, as shown in the figure, the diameter of the bottom end of the self-adjusting back pressure valve is increased from the original 10mm to 13mm, and the length of the damper triangle groove is reduced from the original lmm to 0.7mm, which will enable the front of the slide table. The impulse is reduced by 30%, the transition time is obviously shortened, and the smoothness of the slide motion will also be greatly improved.中文译文液压系统W Arnold1. 绪论液压站称液压泵站,是独立的液压装置。
文献翻译-液压制动系统
附录AHydraulic Brake SystemsWhen you step on the brake pedal,you expect the vehicle to stop.The brake pedal operates a hydraulic that is used for two reasons.First,fluid under pressure can be carried to all parts of the vehicle by small hoses or metal lines without taking up a lot of room of causing routing problems.Second,the hydraulic fluid offers a great mechanical advantage-little foot pressure is required on the pedal,but a great deal of pressure is generated at the wheels.The brake pedal is linked to a piston in the brake master cylinder containing a small piston and a fluid reservoir.Modern master cylinders are actually two separate cylinders.Such a system is called a dual circuit,because the front cylinder is connected to the front brakes and the rear cylinder to the rear brakes.(Some vehicles are connected diagonally).The two cylinders are actually separated,allowing for emergency stopping power should one part of the system fail.The entire hydraulic system from the master cylinder to the wheels is full of hydraulic brake fluid.When the brake pedal is depressed,the piston in the master cylinder are forced to move,exerting tremendous force on the fluid in the lines.The fluid has nowhere to go,and forces the wheel cylinder pistons(drum brakes) orcaliper pistons(disc brakes) to exert pressure on the brake shoes or pads.The friction between the brake shoe and wheel drum or the brake pad and rotor (disc) slows the vehiche and eventually stops it.Also attached to the brake pedal si a switch that lights the brake lights as the pedal is depressed.The lights stay on until the brake pedal is released and returns to its normal position.Each wheel cylinder in a drum brake system contains two pistons,one at either end,which push outward in opposite directions.In disc brake systems,the wheel cylinders are part of the caliper (there can be as many as four or as few as one ).Whether disc or drum type,all pistons use some type of rubber seal to prevent leakage around thepiston,and a rubber dust boot seals the outer of the wheel cylinders against dirt and moisture.When the brake pedal is released,a spring pushes the master cylinder pistons back to their normal positions.Check valves in the master cylinder piston allow fluid to flow toward the wheel cylinders or calipers as the piston returns.Then as the brake shoe return springs pull the brake shoes back to the released position,excess fluid returns to the master cylinder through compensating ports,which have been uncovered as the pistons move back.Any fluid that has leaked from the system will also be replaced through the compensating ports.All dual circuit brake systems use a switch to activate a light,warning of brake failure.The switch si located in a valve mounted near the master cylinder.A piston in the valve reveives pressure on each end from the front and rear brake circuits.When the pressures are balanced,the piston remains stationary,but when one circuit has a leak,greater pressure during the application of the brakes will force the piston to one side or the other,closing the switch and activating the warning light.The light can also be activated by the ignition switch during engine starting or by the parking brake.Front disc,rear drum brake systems also have a metering valve to prevent the front disc brakes from engaging before the rear brakes have contacted the drums.This ensures that the front brakes will not normally be used alone to stop the vehicle.A proportioning valve is also used to limit pressure to the rear brakes to prevent rear wheel lock-up during hard braking.Brake shoes and pads are constructed in a similar.The pad or shoe is composed of a metal backing plate and a priction lining.The lining is either bonded(glued) to the metal,or riveted.Generally,riveted linings provide superior performance,but good quality bonded linings are perfectly adequate.Friction materials will vary between manufacturers and type of pad and the material compound may be referred to as asbestos,organic,semi-metallic,metallic.The difference between these compounds lies in the types and percentages of friction materials used,material binders and performance modifiers.Generally speaking,organic and non-metallic asbestos compound brakes are quiet,easy on rotors and provide good feel.But this comes at the expense of high temperature operation,so they may not be your best choice for heavy duty use or mountiandriving.In most cases,these linings will wear somewhat faster than metallic compound pads,so you will usually replace them more often.But,when using these pads,rotors tend to last longer.Semi-metallic or metallic compound brake linings will vary in performance based on the metallic contents of the compound.Again,generally speaking,the higher the metallic content,the better the friction material will resist heat.This makes them more appropriate for heavy duty applications,but at the expense of braking performance before the pad reaches operating temperature.The first few applications on a cold morning may not give strong braking.Also,metallics and semi-metallics are more likely to squeal,In most cases,metallic compounds last longer than non-metallic pads,but they tend to cause more wear on the rotors.If you use metallic pads,expect to replace the rotors more often.When deciding what type of brake lining is right for you,keep in mind that today’s modern cars have brake materials which are matched to the expected vehicle’s performance capabilities.Changing the material from OEM specification could adversely addect brake feel or responsiveness.Before changing the brake materials,talk to your deaker or parts supplier to help decide what is most appropriate for your application. Remenber that use applications such as towing,stop and go driving,driving down mountain roads,and racing may require a change to a higher performance material.Some more exotic materials are also used in brake linings,among which are Kevlar and carbon compounds.These materials have the capability of extremely good performance for towing,mountain driving or racing.Wear characteristics can be similar to either applications tend to wear like metallic linings,while many of the streetapplications aremore like the non-metallics.附录B液压制动系统当踩下制动踏板，您希望该车辆停下。
液压系统-外文翻译
Hydraulic SystemThere are only three basic methods of transmitting power: electrical, mechanical, and fluid power. Most applications actually use a combination of the three methods to obtain the most efficient overall system. To properly determine which principle method to use, it is important to know the salient features of each type. For example, fluid systems can transmit power more economically over greater distances than can mechanical types. However, fluid systems are restricted to shorter distances than are electrical systems.Hydraulic power transmission system are concerned with the generation, modulation, and control of pressure and flow, and in general such systems include:1.Pumps which convert available power from the prime mover to hydraulic power at the actuator.2.Valves which control the direction of pump-flow, the level of power produced, and the amount of fluid-flow to the actuators. The power level is determined by controlling both the flow and pressure level.3.Actuators which convert hydraulic power to usable mechanical power output at the point required.4.The medium, which is a liquid, provides rigid transmission and control as well as lubrication of components, sealing in valves, and cooling of the system.5.Connectors which link the various system components, provide power conductors for the fluid under pressure, and fluid flow return to tank (reservoir).6.Fluid storage and conditioning equipment which ensure sufficient quality and quantity as well as cooling of the fluid.Hydraulic systems are used in industrial applications such as stamping presses, steel mills , and general manufacturing , agricultural machines , mining industry , aviation , space technology , deep-sea exploration ,transportation , marinetechnology , and offshore gas petroleum exploration . In short, very few people get through a day of their lives without somehow benefiting from the technology of hydraulics.The secret of hydraulic system’s success and widespread use is its versatility and manageability. Fluid power is not hindered by the geometry of the machine as is the case in mechanical systems. Also, power can be transmitted in almost limitless quantities because fluid systems are not so limited by the physical limitations of materials as are the electrical systems. For example, the performance of an electromagnet is limited by the saturation limit of steel. On the other hand, the power limit of fluid systems is limited only by the strength capacity of the material.Industry is going to depend more and more on automation in order to increase productivity. This includes remote and direct control of production operations, manufacturing processes, and materials handling. Fluid power is the muscle of automation because of advantages in the following four major categories.Ease and accuracy of control. By the use of simple levers and push buttons, the operator of a fluid power systems can readily start, stop, speed up or slow down, and position force which provide any desired horsepower with tolerances as precise as one ten-thousandth of an inch.Multiplication of force. A fluid power system (without using cumbersome gears, pulleys, and levers) can multiply forces simply and efficiently from a fraction of an ounce to several hundred tons of output.Constant force or torque. Only fluid power systems are capable of providing constant force or torque regardless of speed changes. This is accomplished whether the work output moves a few inches per hour, several hundred inches per minute, a few revolutions per hour, or thousands of revolutions per minute.Simplicity, safety, economy. In general, fluid power systems use fewer movingparts than comparable mechanical or electrical systems. Thus, they are simpler to maintain and operate. This, in turn, maximizes safety, compactness, and reliability. For example, a new power steering control designed has made all other kinds of power systems obsolete on many off-highway vehicles. The steering unit consists of a manually operated directional control valve and meter in a single body. Because the sterring unit is fully fluid-linked, mechanical linkages, universal joints, bearings, reduction gears, ect . are eliminated. This provides a simple,compact systems.In addition, very little input torque is required to produce the control needed for the toughest applications. This is important where limitations of control space require a small sterring wheel and it becomes necessary to reduce operator fatigue.Additional benefits of fluid power systems include instantly reversible motion, automatic protection against overloads, and infinitely variable speed control. Fluid power systems also have the highest horsepower per weight ratio of any known power source. In spite of all these highly desirable features of fluid power, it is not a panacea for all power transmission problems. Hydraulic systems also have some drawbacks. Hydraulic oils are messy, and leakage is impossible to completely. Also, most hydraulic oils can cause fires if an oil leak occurs in area of hot equipment. There are only three basic methods of transmitting power: electrical, mechanical, and fluid power. Most applications actually use a combination of the three methods to obtain the most efficient overall system. To properly determine which principle method to use, it is important to know the salient features of each type. For example, fluid systems can transmit power more economically over greater distances than can mechanical types. However, fluid systems are restricted to shorter distances than are electrical systems.Hydraulic power transmission system are concerned with the generation, modulation, and control of pressure and flow, and in general such systems include:Pumps which convert available power from the prime mover to hydraulic power at the actuator.Valves which control the direction of pump-flow, the level of power produced, and the amount of fluid-flow to the actuators. The power level is determined by controlling both the flow and pressure level.Actuators which convert hydraulic power to usable mechanical power output at the point required.The medium, which is a liquid, provides rigid transmission and control as well as lubrication of components, sealing in valves, and cooling of the system.Connectors which link the various system components, provide power conductors for the fluid under pressure, and fluid flow return to tank (reservoir).Fluid storage and conditioning equipment which ensure sufficient quality and quantity as well as cooling of the fluid.Hydraulic systems are used in industrial applications such as stamping presses, steel mills , and general manufacturing , agricultural machines , mining industry , aviation , space technology , deep-sea exploration ,transportation , marine technology , and offshore gas petroleum exploration . In short, very few people get through a day of their lives without somehow benefiting from the technology of hydraulics.The secret of hydraulic system’s success and widespread use is its versatility and manageability. Fluid power is not hindered by the geometry of the machine as is the case in mechanical systems. Also, power can be transmitted in almost limitless quantities because fluid systems are not so limited by the physical limitations of materials as are the electrical systems. For example, the performance of an electromagnet is limited by the saturation limit of steel. On the other hand, the power limit of fluid systems is limited only by the strength capacity of the material.Industry is going to depend more and more on automation in order to increase productivity. This includes remote and direct control of production operations, manufacturing processes, and materials handling. Fluid power is the muscle of automation because of advantages in the following four major categories.1. Ease and accuracy of control. By the use of simple levers and push buttons, the operator of a fluid power systems can readily start, stop, speed up or slow down, and position force which provide any desired horsepower with tolerances as precise as one ten-thousandth of an inch.2. Multiplication of force. A fluid power system (without using cumbersome gears, pulleys, and levers) can multiply forces simply and efficiently from a fraction of an ounce to several hundred tons of output.3. Constant force or torque. Only fluid power systems are capable of providing constant force or torque regardless of speed changes. This is accomplished whether the work output moves a few inches per hour, several hundred inches per minute, a few revolutions per hour, or thousands of revolutions per minute.4. Simplicity, safety, economy. In general, fluid power systems use fewer moving parts than comparable mechanical or electrical systems. Thus, they are simpler to maintain and operate. This, in turn, maximizes safety, compactness, and reliability. For example, a new power steering control designed has made all other kinds of power systems obsolete on many off-highway vehicles. The steering unit consists of a manually operated directional control valve and meter in a single body. Because the sterring unit is fully fluid-linked, mechanical linkages, universal joints, bearings, reduction gears, ect . are eliminated. This provides a simple,compact systems.In addition, very little input torque is required to produce the control needed for the toughest applications. This is important where limitations of controlspace require a small sterring wheel and it becomes necessary to reduce operator fatigue.Additional benefits of fluid power systems include instantly reversible motion, automatic protection against overloads, and infinitely variable speed control. Fluid power systems also have the highest horsepower per weight ratio of any known power source. In spite of all these highly desirable features of fluid power, it is not a panacea for all power transmission problems. Hydraulic systems also have some drawbacks. Hydraulic oils are messy, and leakage is impossible to completely. Also, most hydraulic oils can cause fires if an oil leak occurs in area of hot equipment.液压系统仅有以下三种基本方法传递动力：电气，机械和流体。
常用的液压系统的动力源是泵和蓄能器外文文献翻译、中英文翻译、外文翻译
附录外文文献原文：The commonly used sources of power in hydraulic systems are pumps and accumulators .Similarly,accumulator connected to atmosphere will dischange oil at atmosphere pressure until it empty. only when connected to a system having resistance to flow can pressure be developed.Three types of pumps find use in fluid-power systems:rotary,reciprocating or piston-type, and 3,centrifugal pumps.Simple hydraulic system may use but one type of pump . The trend is to use pumps with the most satisfactory characteristics for the specific tasks involved . In matching the characteristics of the pump to the requirements of the hydraulic system , it is not unusual to find two types of pumps in series . For example , a centrifugal pump may be to supercharge a reciprocating pump , or a rotary pump may be used to supply pressurized oil for the contronls associated with a reversing variabledisplacement pumps . Most power systems require positive displacement pumps . At high pressure , reciprocating pumps are often preferred to rotary pumps .1、Rotary pumpsThese are built in many differnt designs and extremely popular in modern fluid power system . The most common rotay-pump designs used today are spurgear , internal gear ,generated rotor , sliding vane ,and screew pumps . Ehch type has advantages that make it most suitable for a given application .2、Gear pumpsGear pumps are the simplest type of fixed displacement hydraulic pump available . This type consists of two external gear , generally spur gear , within a closed-fitting housing . One of the gear is driven directly by the pump drive shaft . It ,in turn , then drives the second gear . Some designs utilize helical gears ,but the spur gear design predominates . Gear pumps operate on a very simple principle . As the gear teeth unmesh , the volume at the inlet port A expands , a partial vacuum on the suction side of the pump will be formed . Fluid from an external reservoir or tank is forced by atmospheric pressure into the pumpinlet . The continuous action of the fluid being carried from the inlet to the discharge side one of the pump forces the fluid into the system .3、Vane pumpsThe vane pump consists of a housing that is eccentric or offset with respect to the drive shaft axis . In some models this inside surface consists of a cam ring that can be rotated to shift the relationship between rotor are rectangular and extend radially from a center radius to the outside diameter of the rotor and from end to end . A rectangular vane that is essentially the same size as the slot is inserted in the slot and is free to slide in and out .As the rotor turns , the vanes thrust outward , and the vane tips track the inner surface of the housing , riding on a thin film of fluid . Two port or end plates that engage the end face of the ring provide axial retention .Centrifugal force generally contributes to outward thrust of the vane . As they ride along the eccentric housing surface , the vane move in and out of the rotor slots . The vane divide the area between the rotor and casing into a series of chambers .The sides of each chamber are formed by two adjacent vanes ,the port or end plates , the pump casing and the rotor . These chambers change in change in volume depending on their respective position about the shaft .As each chamber approaches the inlet port , its vanes move outward and its volume expands , causing fluid to flow into the expanded chamber . Fluid is then carried within the chamber around to the dischange port . As the chamber approaches the discharge port , its vanes are pushed inward ,the volume is reduced , and the fluid is forced out the discharge port .Vane pump speed is limited by vane peripheral speed . High peripheral speed will cause cavitation in suction cavity . which results in pump damage and reduced flow .An imbalance of the vanes can cause the oil film between the vane tips and the cam ring to break down , resulting in metal-to-metal contact and subsequent increased wear and slipage . One metheod applied to eliminate high vane thrust loading is a dual-vane construction .4、Piston-type pumpAll piston pumps operate by allowing oil to flow into a pumping cavity as a piston retreats and then forcing the oil out into another chamber as the piston advances . Design differences among pumps lie primarily in the methods of separating inlet from outlet oil .5、In-line piston pumpThe siplest typeof axial piston pump is the swash plate in-line design .The cylinder are connected though piston shoes and a retracting ring , so that the shoes beat anainst an angled swash plate . As the block turns ,the piston shoes follow the swash plate ,causing the piston to reciprocate . The ports are arranged in the valve plate so that the pistons pass the inlet port as they are being pulled out and pass the outlet port as they are being forcing back in .The angle of the swash plate controls the delibery . Where the swash plate is fixed , the pump is of the constant-displacement type . In the variable-displacement , inline piston pump , the swash plate is moumted on a pivoted yoke . As the swash plate angle is increased , the cylinder stroke is increase , resulting in a greater flow . A pressure compensator control can position the yoke automatically to maintain a constant output pressure .6、BENT-axis piston pumpAs the shaft roates , distance between any one piston and the valving surface changes continually . Each piston moves away from the valving surface during one half of the revolution and toward the valving surface during the other half . The inlet chamber is in line as the pistons move away , and the outletr chamber is in line as the pistons move closer , thus drawing liquiring in during one half of the inlet chamber as the pistons are moving away from the pintle . Thereforce , during rotation , pistons draw liquid into the cylinder bores as they pass the inlet side of the pinntle and force that liquid out of the bores as they pass the outlet side of the pintle . The displacement of this pump varies with the offset angle , the maximum angle being 30 degree ,the minimum zero . Fixed displacement models are usually avaiable with 23 degree angle .In the variable displacement construction a yoke with an external control is used to change the angle . With some contronls , the yoke can be moved over center to reverse the direction of flow from the pump .7、Pump/system interactionPressure-compensated variavle delivery pumps do not require a relief valve in the high pressure line . The pressure compensation feature eliminates the need for the relief valve .In nearly all working systems ,however , at least one is used on just-in-case basis . The use of a pressure compensator , while avoiding dependence on a relief valve , brings on its own problems .The actuator -spring-spool arrangement in the compensator is a dynamic , damped-mass-spring arrangement .However , when the system calls for a chang in axhievetheir maxmum volume as they reach the inlet port , the maximum volume of fluid will ve moved .If the relationship between housing and rotor is changed such that the chambers achieve their minimum of zero volume as they reach the inlet port , the pump delivery will be reduced to zero .Vane pump speed is limited by vane peripheral speed . High peripheral speed will cause cavitation in suction cavity , which results in pump damage and reduced flow . An imbalance of the vanes can cause the oil film between the cane tips and the cam ring to break down , resulting in metal-to-metal contact and subsequent increased wear and slipage . One method applied to eliminate high vane thrust loading is a dual-vane construction . In the dual-vane construction , tow independent vanes are located in each totor slot chmbered edges along the sides and top of each vane from a channel that essentially balances the hydraulic pressure on the top and bottom of each pair of vanes .Centrifugal force cause the vane to follow the contour of the cam-shaped ring .There is just sufficient seal between the vanes and ring without destroying the thin oil film .外文文献中文翻译：常用的液压系统的动力源是泵和蓄能器。
液压系统构成中英文对照外文翻译文献
(文档含英文原文和中文翻译)中英文资料对照外文翻译The hydraulic system constitutionhydraulic system composition department wind and the function, widely is applying on each kind of mechanical device the hydraulic system, the use has the continual fluid fat liquor now, actuates through the hydraulic pump the hydraulic pump the electric motor or the engine mechanical energy transforms the fat liquor the pressure energy, passes through each kind of control valve, delivers took the actuator in the hydraulic cylinder motor, transforms again while the mechanical power actuates the load. Constitutes such hydraulic system each constituent and the function. The hydraulic system characteristic and the use hydraulic pressure took one transmission technology, has its prominent merit:Can produce the very big power, moreover controls easily; May use the pump to obtain very the high pressure (20-30MPa) hydraulic fluid very easily, sends in this pressure oil the hydraulic cylinder then to produce the very big strength; Can in the very wide scope the limitless speed change; To altogether gives the oil motor or the hydraulic cylinder current capacity with the control valve carries on the stepless adjustment, then at will controls its revolving or the translation speed; Very easy to prevent the overload, the security is big; The size slightly strives in a big way, installs the position to be possible the free choice; Output strength adjustment simple accurate, but long-distance control.Hydraulic system use and service, in order to guarantee the mechanical device non-breakdown the work, must follow the factory the use service request.The hydraulic system is infinitely varied, took the different machinery a constituent, its use matters needing attentionalso differ from naturally.The hydraulic system uses and services the duty including the debugging, the inspection, the service and the repair. How debugs? The debugging is causes the new equipment to put the operation or to cause the original equipment to put the operation a series of activities, including the installment, the oil injection, the flushing, the adjustment, runs gathers. The inspection is examined system active status and function is whether correct, including the observation, the survey and tries to move.The maintenance is refers to the guarantee system the normal function, the few attrition and the replacement wearing parts, including the cleaning up and the replacement components, namely trades the oil, trades ponders the core, trades the seal.The repair is system reply function a series of activities which causes to crash.First must according to the breakdown phenomenon determine expires the spot and verifies the expiration reason, this is the so-called breakdown diagnosis. Then the replacement expiration part, makes the mechanical device to restore the work, this named repair.The expiration part should return the plant to repair.Time use service matters needing attention: When security, use and service hydraulic system, when most important question pays attention to the security, for guarantees the security, has the pressure when the system does not have to loosen the pipe connection, the screw joint or the part.Certainly must put first down the load, causes the pump engine off and releases the accumulator the pressure oil, then opens the thing again, does not have the oil used to work. Although many practical security taboo into general knowledge, but the attention often concentrates in the breakdown phenomenon, but neglects the latent danger.Therefore, in starts to repair the system reason this implementation standardization the engine off procedure, after the repair draws up invests the movement, should implement standardized the again start procedure:Engine off procedure it including following several aspects:1. Puts the low suspension the load or carries on the machinery supports and protections to it.2. Release system3. In release accumulator pressure oil4. Release pressure intensifier both sides pressure oil5. Cut-off electricity control system6.DumpStarts the procedure including following several aspects:1. Elimination expiration root2. If the component failure or the replacement period pollutant enters the system, then according to needs to clean up or the flushing system3. Confirms the part correctly unmistakable4. Confirms the hydraulic pressure connection correctly unmistakable5. Confirms the electrical connection correctly unmistakable6. Adjustable part to secure state7. Fills the oil for the pump and the motor shell8. According to needs to refuel to the system and to deflate9. Relieves the secure interconnection to protect10. Calls the alarm bell and the notice all presents the personnel soon to restart11.Starting systemThe item which this is carries on when service must pay attention, in regarding its sanitary, when service also must pay attention, when service hydraulic system, must do utmost the attention absolutely clean Arab League condition, because the pollutant is the hydraulic system most dangerous enemy.Does not have to carry on the polish and the welding work in the service hydraulic system scene. Loosens in front of the thread must its outside clean first cleanly.With clean returns to protects changes passes over the system the interior to use to open the mouth to seal, guards against the pollutant to enter thesystem.Cleans up when the fuel tank does not permit the use cotton and kapok silk and the rags.Must pass through the filter to the system oil injection.In the tubing, refuels with the flushing is the maintenance clean important link, its matters needing attention are as follows:1. The tubing pipe or the hose damage when must replace immediately.When chooses the pipe, the hose, the screw connector or the flange, must guarantee the pressure rated value (i.e. wall thickness, material quality and so on) satisfy the operation requirements.The hard tube must use the seamless steel pipe.The steel pipe and the metal pipe connection must clean absolutely before the installment, does not have the oil dirt, to scale, the welding, the scrap and so on.May use the steel wire brush, the tube cleaner to clean up or the acid pickling.In front of the acid pickling pipe must carry on degreasing processing, after the acid pickling must clean thoroughly. After cutting in the pipe bank or ridge between fields should the articulation awl hole, remove the burr which possibly has, but cannot ream excessively in order to avoid sells the weak connection.After assembly the pipe does not have again to weld or the gas welding, because is unable to clean up.The hose should the curved several times in order to release any detention the dirty thing.In front of the elbow piece the tubing wants the annealing, prevented when elbow piece the corrugation or changes flat.Wants the accurate elbow piece, enable the pipe then not to arrive after the elastic deformation. The flange must in the fitting surface coordinate smoothly before, and with the length suitable bolt fastening, whether there is the screw connector does install should inspect in the thread the metal burr, in the straight thread does not permit the use seal bandage.If the drive pipe must deposit period of time, should stop up the orifice to prevent the foreign matter enters.But does not have to use the rags or other moves the capital to stop up the orifice, because this only can bring the contamination concern, should use the size appropriate seal cap.2. Refuels the oil drum to want horizontal-type depositing, as far as possible deposits in the room or the awning, opens in front of the oil tung, cleans the barrel to go against and the bung thoroughly, prevented the soil and other outside pollutant enter the fat liquor.Only with the clean vessel, the hose and so on transports the fat liquor from the oil drum to the fuel tank.The recommendation with has at least in the 25um filter feeding pump. Provides 200 goals in the fuel tank oiling tube to ponder the net.The filter is actually specially for the system need oil fluid variety use.Sometimes also discovers the pollutant in the new fat liquor, therefore should for work through the portable purifier the hydraulic system tops up. When portable purifier hose involvement fuel tank, should use cloth attachment cleaning which clean does not shed hair to be clean, prevented the soil and other impurities enter the system.3.Before flushing flushing should take down the precise system part, but installs the pipe nipple in its position or hollow.From the main pipeline which flushes is dismantled the system to ponder the core.The flushing current capacity should for the system anticipated current capacity 2-2.5 times.If possible, use heat flush fluid (85℃).Each time only flushes a leg, from most approaches the wash out pump the return route start, to the downstream advancement, this possibly must additionally build in turn in the system up to the valve, realizes this kind of plan. Cannot use the system pump to take the wash out pump.Generally speaking, the power type pump like centrifugal pump and so on may provide the enough flood peak and the great current capacity, the movement quite is economical, and to flushes the period circulation the pollutant to have the good es the capacity in the flushing system with to use the flushing filter which the current capacity matches, the filtration precision to be as far as possible high, does not have to be lower than the recommendation system filtration precision. If has the possibility, uses the assistance to flush the fuel tank to avoid the pollutant being detained in the system fuel tank.The establishment fat liquor sample plan inspects dustiness, thus determined when finished the flushing procedure.After flushing, takes all measures to prevent when rewiring work part leads the pollutant.4.The replacement part part model must correct unmistakable.When if cannot find the similar model the part to have to use the similar part substitutes, must pay attention to the function, the parameter, the connection size is whether consistent, but also must pay attention installs the position, the ambient temperature, the working voltage and so on.The old seal packing collar must replace, does not permit two uses.The bolt and the screw connector must even screw tight the big stipulation the torque, prevents the part distortion influence work. The adjustable part like delivery valve, the flow valve, the variable displacement pump and so on must establish.5.When accumulator accumulator pressure vessel, Asia locality related safety rule compulsory control.In is loaded with on the accumulator hydraulic system carries on in front of any work, must first download the system pressure.The accumulator shell does not permit the welding and the processing, does not repair when possibly causes the serious accident, therefore must have to repair the accumulator returns delivers the plant to carry on the repair.Hydraulic pump selection: The hydraulic pump is the hydraulic system power supply.Must select can adapt the pressure which the actuator requests to have the return route pump, simultaneously must consider fully the reliability, the life Maintainability one side and so on elect the pump can plant the long-term movement in the system.The hydraulic pump type are extremely many, its characteristic also has the very big difference. Chooses when the hydraulic pump must consider the factor has working pressure, current capacity, rotational speed, quota or variable, variable way, volumetric efficiency, overall effectiveness index, the prime mover type, the noise, the pressure oscillation rate, self-absorption ability and so on, but also must consider and the hydraulic fluid compatibility, the size, the weight, the economy, Maintainability, these factors.The hydraulic pump discharge pressure should be the actuator needs the pressure, the tubing pressure loses, the control valve sum of pressure loss, it does not have to surpass in the sample the rated pressure, when the emphasis security, the reliability.Also should leave leeway the big leeway.In when sample highest working pressure when short-term impact permits pressure.If each circulation plants all has the impact pressure, the pump life can reduce obviously, even the pump can damage.Hydraulic pump life: The hydraulic pump is the hydraulic system power part, its function is transforms the prime mover mechanical energy the liquid the pressure energy, refers to in the hydraulic system the oil pump, it provides the power to the entire hydraulic system.Hydraulic pump structural style common toothed wheel pump, vane pump and ram pump. Affects the hydraulic pump the service life factor to be very many, except outside pump own design, manufacture factor and some with pump use Guanyuan (for example shaft coupling, oil filter and so on) selects, in the test run movement process operation and so on also concerns.1.The air compressorselects the air compressor the basis is the working pressure and the current capacity which the pneumatic system needs.At present, the pneumatic system commonly used working pressure is 0.5~0.8MPa, may select the rated pressure is directly the 0.7~1MPa low-pressure air compressor, the special need fluid may select, high-pressured or the ultrahigh voltage air compressor. When determination air compressor air displacement, should satisfy the biggest gas consumption which each air operated equipment needs (to be supposed to transform into free air gas consumption) the sum.(1) was mad the source refining equipmentgeneral use the air compressor all uses the oil lubrication, the air is compressed in the air compressor, the temperature may elevate 140~170℃, by now were partial the lubricating oil to turn the gas, mixed in the compressed air, in addition in the air water and the dust, formed included mix impurity and so on the water vapor, oil gas, dust compressed air.Ifprovides this kind of compressed air to the air operated equipment use, will be able to have following adverse consequences:Gathers in the compressed air the oil gas to gather in the gas storage fills forms the combustible, even has the detonation danger; Simultaneously the oil vaporizes after the high temperature forms the organic acid, causes the hardware to corrode, affects the equipment the life.(2)The mix impurity deposition in the pipeline and the air operated part, causes to pass flows the area to reduce, circulation drag increment, the overall system work is unstable, when serious, system knock off.(3)In the compressed air water vapor can congeal the waterdrop under certain pressure and the temperature, can cause the pipeline and the assistance part in the cold season because of freezes destroys.(4)In the compressed air dust has the abrasive action to the air operated part movement part, causes it attrition to be serious, affects their life.Thus it can be seen, establishes in the pneumatic system eliminates the water, eliminates the oil, the dust removal and dry and so on was mad the source refining equipment is extremely essential.Second, the air operated assistance partair operated part interior has many relative slippers, somewhat relative slipper depends on the seal packing collar to seal.In order to reduce transports the moving parts relatively the friction force, guaranteed the part movement is normal; In order to reduce the packing material the attrition, prevents divulging; In order to prevent the pipeline and the metal part corrosion, lengthens the part service life, guaranteed the good lubrication is extremely important.The lubrication may not divide into and spurts the mist lubrication for the oil lubrication.Some many air operated application domain does not allow to spurt the mist lubrication.If food and the drugs packing, in the transportation process, the oil granule returns to pollution food and the drugs; The oil granule can affect certain raw material for industry, the chemicals nature; The oil mist can affect the high-level spray coating surface and the electronic component surface quality; The oil mist can affect the measuring instrument true the survey; The oil mist can harm the human body health and so on.Therefore at present uses the mist lubrication to reduce gradually, does not give the oil lubrication already very popularly.Still did not use the rubber material for the oil lubrication to take the glide spot the seal, but sealed has the detention tank special structure, in order to memory lubricant.Other components should use not the easy rusty metal material or the nonmetallic material.For the oil lubrication part also may not to the oil use, once but gives the oil, does not have the midway to stop feed.At the same time, must prevent the condensed water enters in the part, in order to avoid flushes the lubricant.Not only has not saved the lubricating utensils and the lubricating oil for the oil lubrication part, improved the working conditions, moreover reduced the maintenance work load, reduced the cost.Moreover, also improved the lubrication condition.Its lubrication effect with the transit discharge, the pressure height, the tubing condition and so on all has nothing to do with.Also does not exist forgot refuels creates the breakdown the matter.The mist lubrication part has the oil mist and the centralism lubrication part two kinds.In (1) pneumatic system each kind of air valve, the air cylinder, the gas motor and so on, its movable part all needs to lubricate, but take the compressed air all seals the air chamber as the power air operated part, cannot use the general method oil injection, only can mix in by some method the oil in the air current, the belt to the place which needs to lubricate.The oil mist is this kind of kind of special oil injection installment.After it causes the lubrication oilatomization to pour into in the air current, enters the part along with the air which needs to lubricate. Refuels with this method, has the lubrication to be even, to be stable, the oil consumption few and does not need characteristics and so on big oil storage equipment.(2) air strainer is in the pneumatic system important link, is further filters the dust compressed air the impurity.The filter form are very many, the commonly used type includes: The disposable filter and two filter, have been requesting the high special occasion, may use the highly effective filter.99. In the pneumatic actuator system, called generally the filter, the oil mist, the pressure relief valve for air operated three association (or three big-ticket items), are in the pneumatic system the essential auxiliary unit.(3) silencerpneumatic circuit and the hydraulic pressure return route are different, it does not suppose the exhaust pipeline generally, after the compressed air use the direct platoon person atmosphere, because the gas rapidly inflation and forms the turbulent flow phenomenon, will have the intense exhaust noise.The exhaust speed and the power are bigger, the exhaust noise is bigger, may generally big 100~200dB.The noise harms people's physical and moral integrity directly, must eliminate or weaken.For the noise reduction, generally often installs the silencer in the pneumatic system air vent.The air operated functional elementair operated functional element is transforms in the pneumatic system the compressed air pressure energy the mechanical energy the part.It including air cylinder friendly motor.The air cylinder uses in realizing the straight reciprocating motion or swinging, was mad the motor uses in realizing the continual gyroscopic motion.First, The air cylinderair cylinder is in the pneumatic system the most commonly used one kind of functional element, compares with the hydraulic cylinder, it has the structure simply, pollutes, the movement few keen, responded quick, easy to make, easily to service, the cost low status merit, but because the thrust force is small, widely uses in the underloading system.(1) The air cylinder classifiedbasis air cylinder exploitation conditions are different, its structure, the shape, the type are very many, below introduces several kind of classifications.May divide into according to the compressed air function in the piston end surface direction: List function air cylinder and double-acting air cylinder.(2)Different may divide into according to the structure characteristic: Plunger-type air cylinder, plunger air cylinder, film air cylinder, leaf blade type oscillating cylinder, gear strip type oscillating cylinder and so on.(3) May divide into according to the air cylinder function: Ordinary air cylinder and special air cylinder.The ordinary air cylinder refers to the general plunger-type air cylinder, uses in the not special request the situation.The special air cylinder uses in having the special request situation, like was mad - - the fluid damping cylinder, the film air cylinder, flush are mad the air cylinder, the expansion and contraction air cylinder and so on.(4) According to installs the way differently to be possible to divide into: The ear place type, the flange type, sell the shaft type and the flange type and so on.(二)Common air cylinder principle of work and applicationThe ordinary air cylinder principle of work and the use are similar to the hydraulic cylinder, here no longer give unnecessary detail, below only introduces the special air cylinder.1. Is mad - - the fluid damping cylinderbecause the ordinary air cylinder works time, the compressed gas condensibility is big, when the outside work load change is big, the air cylinder appears “crawling” or “self-propelled” the phenomenon, the stability When therefore the equip ment precision is high, the air cylinder work stable request is also high, often uses was mad - - the fluiddamping cylinder is becomes by the air cylinder and the hydraulic cylinder combination, take the compressed air as an energy, by the hydraulic fluid took the control adjustment air cylinder velocity of movement the medium, the use liquid incompressibility control liquid displacement, adjusts the piston the velocity of movement, obtains the piston the steady motion.2. The film air cylinderfilm type air cylinder is replaces the piston by the thin film the air cylinder.It mainly by the cylinder body, the diaphragm, the diaphragm capsule and the connecting rod and so on the major parts is composed.Has the list to affect the type and the double-acting type.液压系统的构成液压系统的组成部风及其作用，如今在各种机械设备上广泛应用着的液压系统,使用具有连续流动性的油液,通过液压泵把驱动液压泵的电动机或发动机的机械能转换成油液的压力能,经过各种控制阀,送到作为执行器的液压缸马达中,再转换乘机械动力去驱动负载.构成这样的液压系统的各个组成部分及其作用.液压系统的特点和用途液压作为一种传动技术,有其突出的优点:能产生很大的动力,而且控制容易；可以用泵很容易地得到很高压力(20-30MPa)的液压油,把此压力油送入液压缸即可产生很大的力；能在很宽范围内无极变速；用控制阀对共给液压马达或液压缸的流量进行无级调整,即可随意控制其旋转或直线运动的速度；很容易防止过载,安全性大；尺寸小出力大,安装位置可自由选择；输出力的调整简单准确,可远程控制.液压系统的使用与维修，为了保证机械设备无故障的工作，必须遵循制造厂的使用维修要求。
液压控制系统-液压液外文文献翻译、中英文翻译
CHAPTER 3HYDRAULIC FLUIDSDuring the design of equipment that requires fluid power, many factors are considered in selecting the type of system to be used—hydraulic, pneumatic, or a combination of the two. Some of the factors are required speed and accuracy of operation, surrounding atmospheric conditions, economic conditions, availability of replacement fluid, required pressure level, operating temperature range, contamination possibilities, cost of transmission lines, limitations of the equipment, lubricity, safety to the operators, and expected service life of the equipment.After the type of system has been selected, many of these same factors must be considered in selecting the fluid for the system. This chapter is devoted to hydraulic fluids. Included in it are sections on the properties and characteristics desired of hydraulic fluids; types of hydraulic fluids; hazards and safety precautions for working with, handling, and disposing of hydraulic liquids; types and control of contamination; and sampling.PROPERTIESIf fluidity (the physical property of a substance that enables it to flow) and incompressibility were the only properties required, any liquid not too thick might be used in a hydraulic system. However, a satisfactory liquid for a particular system must possess a number of other properties. The most important properties and some characteristics are discussed in the following paragraphs.VISCOSITYViscosity is one of the most important properties of hydraulic fluids. It is a measure of a fluids resistance to flow. A liquid, such as gasoline, which flows easily, has a low viscosity; and a liquid, such as tar, which flows slowly, has a high viscosity. The viscosity of a liquid is affected by changes in temperature and pressure. As the temperature of a liquid increases, its viscosity decreases. That is, a liquid flows more easily when it is hot than when it is cold. The viscosity of a liquid increases as the pressure on the liquid increases.A satisfactory liquid for a hydraulic system must be thick enough to give a good seal at pumps, motors, valves, and so on. These components depend on close fits for creating and maintaining pressure. Any internal leakage through these clearances results in loss of pressure, instantaneous control, and pump efficiency. Leakage losses are greater with thinner liquids (low viscosity). A liquid that is too thin will also allow rapid wearing of moving parts, or of parts that operate under heavy loads. On the other hand, if the liquid is too thick (viscosity too high), the internal friction of the liquid will cause an increase in the liquids flow resistance through clearances of closely fitted parts, lines, and internal passages. This results in pressuredrops throughout the system, sluggish operation of the equipment, and an increase in power consumption.Measurement of ViscosityViscosity is normally determined by measuring the time required for a fixed volume of a fluid (at a given temperature) to flow through a calibrated orifice or capillary tube. The instruments used to measure the viscosity of a liquid are known as viscometers or viscosimeters.Figure 3-1.Saybolt viscometer.Several types of viscosimeters are in use today. The Say bolt viscometer, shown in figure 3-1, measures the time required, in seconds, for 60 milliliters of the tested fluid at 100°F to pass through a standard orifice. The time measured is used to express the fluids viscosity, in Saybolt universal seconds or Saybolt furol seconds.Figure 3-2.Various styles of glass capillary viscometers.The glass capillary viscometers, shown in figure 3-2, are examples of the second type of viscometer used. These viscometers are used to measure kinematic viscosity. Like the Saybolt viscometer, the glass capillary measures the time in seconds required for the tested fluid to flow through the capillary. This time is multiplied by the temperature constant of the viscometer in use to provide the viscosity, expressed in centistokes.The following formulas may be used to convert centistokes (cSt units) to approximate Say bolt universal seconds (SUS units). For SUS values between 32 and 100: SUS SUS cST 195226.0-⨯= For SUS values greater than 100: SUS SUS cST 195220.0-⨯=Although the viscometers discussed above are used in laboratories, there are other viscometers in the supply system that is available for local use. These viscometers can be used to test the viscosity of hydraulic fluids either prior to their being added to a system or periodically after they have been in an operating system for a while.Additional information on the various types of viscometers and their operation can be found in the Physical Measurements Training Manual, NA V AIR 17-35QAL-2.Viscosity IndexThe viscosity index (V.I.) of oil is a number that indicates the effect of temperature changes on the viscosity of the oil. A low V.I. signifies a relatively large change of viscosity with changes of temperature. In other words, the oil becomes extremely thin at high temperatures and extremely thick at low temperatures. On the other hand, a high V.I. signifies relatively little change in viscosity over a wide temperature range.Ideal oil for most purposes is one that maintains a constant viscosity throughout temperature changes. The importance of the V.I. can be shown easily by considering automotive lubricants. Oil having a high V.I. resists excessive thickening when the engine is cold and, consequently, promotes rapid starting and prompt circulation; it resists excessive thinning when the motor is hot and thus provides full lubrication and prevents excessive oil consumption.Another example of the importance of the V.I. is the need for high V.I. hydraulic oil for military aircraft, since hydraulic control systems may be exposed to temperatures ranging from below –65°F at high altitudes to over 100°F on the ground. For the proper operation of the hydraulic control system, the hydraulic fluid must have a sufficiently high V.I. to perform its functions at the extremes of the expected temperature range.Liquids with a high viscosity have a greater resistance to heat than low viscosity liquids which have been derived from the same source. The average hydraulic liquid has a relatively low viscosity. Fortunately, there is a wide choice of liquids available for use in the viscosity range required of hydraulic liquids.The V.I. of an oil may be determined if its viscosity at any two temperatures is known. Tables, based on a large number of tests, are issued by the American Society for Testing and Materials (ASTM). These tables permit calculation of the V.I. from known viscosities.LUBRICATING POWERIf motion takes place between surfaces in contact, friction tends to oppose the motion. When pressure forces the liquid of a hydraulic system between the surfaces of moving parts, the liquid spreads out into a thin film which enables the parts to move more freely. Different liquids, including oils, vary greatly not only in their lubricating ability but also in film strength. Film strength is the capability of a liquid to resist being wiped or squeezed out from between the surfaces when spread out in an extremely thin layer. A liquid will no longer lubricate if the film breaks down, since the motion of part against part wipes the metal clean of liquid.Lubricating power varies with temperature changes; therefore, the climatic and working conditions must enter into the determination of the lubricating qualities of a liquid. Unlike viscosity, which is a physical property, the lubricating power and film strength of a liquid isdirectly related to its chemical nature. Lubricating qualities and film strength can be improved by the addition of certain chemical agents.CHEMICAL STABILITYChemical stability is another property which is exceedingly important in the selection of a hydraulic liquid. It is defined as the liquids ability to resist oxidation and deterioration for long periods. All liquids tend to undergo unfavorable changes under severe operating conditions. This is the case, for example, when a system operates for a considerable period of time at high temperatures.Excessive temperatures, especially extremely high temperatures, have a great effect on the life of a liquid. The temperature of the liquid in the reservoir of an operating hydraulic system does not always indicate the operating conditions throughout the system. Localized hot spots occur on bearings, gear teeth, or at other points where the liquid under pressure is forced through small orifices. Continuous passage of the liquid through these points may produce local temperatures high enough to carbonize the liquid or turn it into sludge, yet the liquid in the reservoir may not indicate an excessively high temperature.Liquids may break down if exposed to air, water, salt, or other impurities, especially if they are in constant motion or subjected to heat. Some metals, such as zinc, lead, brass, and copper, have undesirable chemical reactions with certain liquids.These chemical reactions result in the formation of sludge, gums, carbon, or other deposits which clog openings, cause valves and pistons to stick or leak, and give poor lubrication to moving parts. Once a small amount of sludge or other deposits is formed, the rate of formation generally increases more rapidly. As these deposits are formed, certain changes in the physical and chemical properties of the liquid take place. The liquid usually becomes darker, the viscosity increases and damaging acids are formed.The extent to which changes occur in different liquids depends on the type of liquid, type of refining, and whether it has been treated to provide further resistance to oxidation. The stability of liquids can be improved by the addition of oxidation inhibitors. Inhibitors selected to improve stability must be compatible with the other required properties of the liquid.FREEDOM FROM ACIDITYAn ideal hydraulic liquid should be free from acids which cause corrosion of the metals in the system. Most liquids cannot be expected to remain completely no corrosive under severe operating conditions. The degree of acidity of a liquid, when new, may be satisfactory; but after use, the liquid may tend to become corrosive as it begins to deteriorate.Many systems are idle for long periods after operating at high temperatures. This permits moisture to condense in the system, resulting in rust formation.Certain corrosion- and rust-preventive additives are added to hydraulic liquids. Some of these additives are effective only for a limited period. Therefore, the best procedure is to use the liquid specified for the system for the time specified by the system manufacturer and to protect the liquid and the system as much as possible from contamination by foreign matter, from abnormal temperatures, and from misuse.FLASHPOINTFlashpoint is the temperature at which a liquid gives off vapor in sufficient quantity to ignite momentarily or flash when a flame is applied. A high flashpoint is desirable for hydraulic liquids because it provides good resistance to combustion and a low degree of evaporation at normal temperatures. Required flashpoint minimums vary from 300°F for the lightest oils to 510°F for the heaviest oils.FIRE POINTFire point is the temperature at which a substance gives off vapor in sufficient quantity to ignite and continue to burn when exposed to a spark or flame. Like flashpoint, a high fire point is required of desirable hydraulic liquids.MINIMUM TOXICITYToxicity is defined as the quality, state, or degree of being toxic or poisonous. Some liquids contain chemicals that are a serious toxic hazard. These toxic or poisonous chemicals may enter the body through inhalation, by absorption through the skin, or through the eyes or the mouth. The result is sickness and, in some cases, death. Manufacturers of hydraulic liquids strive to produce suitable liquids that contain no toxic chemicals and, as a result, most hydraulic liquids are free of harmful chemicals. Some fire-resistant liquids are toxic, and suitable protection and care in handling must be provided.DENSITY AND COMPRESSIBILITYA fluid with a specific gravity of less than 1.0 is desired when weight is critical, although with proper system design, a fluid with a specific gravity greater than one can be tolerated. Where avoidance of detection by military units is desired, a fluid which sinks rather than rises to the surface of the water is desirable. Fluids having a specific gravity greater than 1.0 are desired, as leaking fluid will sink, allowing the vessel with the leak to remain undetected.Recall from chapter 2 that under extreme pressure a fluid may be compressed up to 7 percent of its original volume. Highly compressible fluids produce sluggish system operation. This does not present a serious problem in small, low-speed operations, but it must be considered in the operating instructions.FOAMING TENDENCIESFoam is an emulsion of gas bubbles in the fluid. Foam in a hydraulic system results fromcompressed gases in the hydraulic fluid. A fluid under high pressure can contain a large volume of air bubbles. When this fluid is depressurized, as when it reaches the reservoir, the gas bubbles in the fluid expand and produce foam. Any amount of foaming may cause pump cavitations and produce poor system response and spongy control. Therefore, defaming agents are often added to fluids to prevent foaming. Minimizing air in fluid systems is discussed later in this chapter.CLEANLINESSCleanliness in hydraulic systems has received considerable attention recently. Some hydraulic systems, such as aerospace hydraulic systems, are extremely sensitive to contamination. Fluid cleanliness is of primary importance because contaminants can cause component malfunction, prevent proper valve seating, cause wear in components, and may increase the response time of servo valves. Fluid contaminants are discussed later in this chapter.The inside of a hydraulic system can only be kept as clean as the fluid added to it. Initial fluid cleanliness can be achieved by observing stringent cleanliness requirements (discussed later in this chapter) or by filtering all fluid added to the system.TYPES OF HYDRAULIC FLUIDSThere have been many liquids tested for use in hydraulic systems. Currently, liquids being used include mineral oil, water, phosphate ester, water-based ethylene glycol compounds, and silicone fluids. The three most common types of hydraulic liquids are petroleum-based, synthetic fire-resistant, and water-based fire-resistant.PETROLEUM-BASED FLUIDSThe most common hydraulic fluids used in shipboard systems are the petroleum-based oils. These fluids contain additives to protect the fluid from oxidation (antioxidant), to protect system metals from corrosion (anticorrosion), to reduce tendency of the fluid to foam (foam suppressant), and to improve viscosity.Petroleum-based fluids are used in surface ships，electro hydraulic steering and deck machinery systems, submarines，hydraulic systems, and aircraft automatic pilots, shock absorbers, brakes, control mechanisms, and other hydraulic systems using seal materials compatible with petroleum-based fluids.SYNTHETIC FIRE-RESISTANT FLUIDS Petroleum-based oils contain most of the desired properties of a hydraulic liquid. However, they are flammable under normal conditions and can become explosive when subjected to high pressures and a source of flame or high temperatures. Nonflammable synthetic liquids have been developed for use in hydraulic systems where fire hazards exist.Phosphate Ester Fire-Resistant FluidPhosphate ester fire-resistant fluid for shipboard use is covered by specification MIL- H-19457. There are certain trade names closely associated with these fluids. However, the only acceptable fluids conforming to MIL-H-19457 are the ones listed on the current Qualified Products List (QPL) 19457. These fluids will be delivered in containers marked MIL-H-19457C or a later specification revision. Phosphate ester in containers marked by a brand name without specification identification must not be used in shipboard systems, as they may contain toxic chemicals.These fluids will burn if sufficient heat and flame are applied, but they do not support combustion. Drawbacks of phosphate ester fluids are that they will attack and loosen commonly used paints and adhesives, deteriorate many types of insulations used in electrical cables, and deteriorate many gasket and seal materials. Therefore, gaskets and seals for systems in which phosphate ester fluids are used are manufactured of specific materials. Naval Ships，Technical Manual, chapter 262, specifies paints to be used on exterior surfaces of hydraulic systems and components in which phosphate ester fluid is used and on ship structure and decks in the immediate vicinity of this equipment. Naval Ships，Technical Manual, chapter 078, specifies gasket and seal materials used. NA V AIR 01-1A-17 also contains a list of materials resistant to phosphate ester fluids.Trade names for phosphate ester fluids, which do not conform to MIL-H-19457 include Pydraul、Skydrol、and Fire Safe.PHOSPHATE ESTER FLUID SAFETY.—as a maintenance person, operator, supervisor, or crew member of a ship, squadron, or naval shore installation, you must understand the hazards associated with hydraulic fluids to which you may be exposed.Phosphate ester fluid conforming to specification MIL-H-19457 is used in aircraft elevators, ballast valve operating systems, and replenishment-at-sea systems. This type of fluid contains a controlled amount of neurotoxic material. Because of the neurotoxic effects that can result from ingestion, skin absorption, or inhalation of these fluids, be sure to use the following precautions:1. Avoid contact with the fluids by wearing protective clothing.2. Use chemical goggles or face shields to protect your eyes.3. If you are expected to work in an atmosphere containing a fine mist or spray, wear a continuous-flow airline respirator.4. Thoroughly clean skin areas contaminated by this fluid with soap and water.5. If you get any fluid in your eyes, flush them with running water for at least 15 minutes and seek medical attention.If you come in contact with MIL-H-19457 fluid, report the contact when you seek medical aid and whenever you have a routine medical examination.Naval Ships，Technical Manual, chapter 262, contains a list of protective clothing, along with national stock numbers(NSN),for use with fluids conforming to MIL-H-19457.It also contains procedures for repair work and for low-level leakage and massive spills cleanup.PHOSPHATE ESTER FLUID DISPOSAL.—Waste MIL-H-19457 fluids and refuse (rags and other materials) must not be dumped at sea. Fluid should be placed in bung-type drums. Rags and other materials should be placed in open top drums for shore disposal. These drums should be marked with a warning label stating their content, safety precautions, and disposal instructions. Detailed instructions for phosphate ester fluids disposal can be found in Naval Ships, Technical Manual, chapter 262, and OPNA VINST 5090.1.Silicone Synthetic Fire-Resistant FluidsSilicone synthetic fire-resistant fluids are frequently used for hydraulic systems which require fire resistance, but which have only marginal requirements for other chemical or physical properties common to hydraulic fluids. Silicone fluids do not have the detrimental characteristics of phosphate ester fluids, nor do they provide the corrosion protection and lubrication of phosphate ester fluids, but they are excellent for fire protection. Silicone fluid conforming to MIL-S-81087 is used in the missile hold-down and lockout system aboard submarines.Lightweight Synthetic Fire-Resistant Fluids In applications where weight is critical, lightweight synthetic fluid is used in hydraulic systems. MIL-H-83282 is a synthetic, fire-resistant hydraulic fluid used in military aircraft and hydrofoils where the requirement to minimize weight dictates the use of a low-viscosity fluid. It is also the most commonly used fluid in aviation support equipment. NA V AIR 01-1A-17 contains additional information on fluids conforming to specification MIL-H-83282.WATER-BASED FIRE-RESISTANT FLUIDS The most widely used water-based hydraulic fluids may be classified as water-glycol mixtures and water-synthetic base mixtures. The water-glycol mixture contains additives to protect it from oxidation, corrosion, and biological growth and to enhance its load-carrying capacity.Fire resistance of the water mixture fluids depends on the vaporization and smothering effect of steam generated from the water. The water in water-based fluids is constantly being driven off while the system is operating. There- fore, frequent checks to maintain the correct ratio of water are important.The water-based fluid used in catapult retracting engines, jet blast deflectors, and weapons elevators and handling systems conforms to MIL-H-22072.The safety precautions outlined for phosphate ester fluid and the disposal of phosphate ester fluid also apply to water-based fluid conforming to MIL-H-22072.CONTAMINATIONHydraulic fluid contamination may be described as any foreign material or substance whose presence in the fluid is capable of adversely affecting system performance or reliability. It may assume many different forms, including liquids, gases, and solid matter of various compositions, sizes, and shapes. Solid matter is the type most often found in hydraulic systems and is generally referred to as particulate contamination. Con- termination is always present to some degree, even in new, unused fluid, but must be kept below a level that will adversely affect system operation. Hydraulic contamination control consists of requirements, techniques, and practices necessary to minimize and control fluid contamination.CLASSIFICATIONThere are many types of contaminants which are harmful to hydraulic systems and liquids. These contaminants may be divided into two different classes—particulate and fluid.Particulate ContaminationThis class of contaminants includes organic, metallic solid and inorganic solid contaminants. These contaminants are discussed in the following paragraphs.ORGANIC CONTAMINATION.—Organic solids or semisolids found in hydraulic systems are produced by wear, oxidation, or polymerization. Minute particles of O-rings, seals, gaskets, and hoses are present, due to wear or chemical reactions. Synthetic products, such as neoprene, silicones, and hypalon, though resistant to chemical reaction with hydraulic fluids, produce small wear particles. Oxidation of hydraulic fluids increases with pressure and temperature, although antioxidants are blended into hydraulic fluids to minimize such oxidation.The ability of a hydraulic fluid to resist oxidation or polymerization in service is defined as its oxidation stability. Oxidation products appear as organicacids,asphaltics,gums,and varnishes. These products combine with particles in the hydraulic fluid to form sludge. Some oxidation products are oil soluble and cause the hydraulic fluid to increase in viscosity; other oxidation products are not oil soluble and form sediment.METALLIC SOLID CONTAMINATION.—Metallic contaminants are almost always present in a hydraulic system and will range in size from microscopic particles to particles readily visible to the naked eye. These particles are the result of wearing and scoring of bare metal parts and plating materials, such as silver and chromium. Although practically all metals commonly used for parts fabrication and plating may be found in hydraulic fluids, themajor metallic materials found are ferrous, aluminum, and chromium particles. Because of their continuous high-speed internal movement, hydraulic pumps usually contribute most of the metallic particulate contamination present in hydraulic systems. Metal particles are also produced by other hydraulic system components, such as valves and actuators, due to body wear and the chipping and wearing away of small pieces of metal plating materials.INORGANIC SOLID CONTAMINATION.—This contaminant group includes dust, paint particles, dirt, and silicates. Glass particles from glass bead penning and blasting may also be found as contaminants. Glass particles are very undesirable contaminants due to their abrasive effect on synthetic rubber seals and the very fine surfaces of critical moving parts. Atmospheric dust, dirt, paint particles, and other materials are often drawn into hydraulic systems from external sources. For example, the wet piston shaft of a hydraulic actuator may draw some of these foreign materials into the cylinder past the wiper and dynamic seals, and the contaminant materials are then dispersed in the hydraulic fluid. Contaminants may also enter the hydraulic fluid during maintenance when tubing, hoses, fittings, and components are disconnected or replaced. It is therefore important that all exposed fluid ports be sealed with approved protective closures to minimize such contamination.Fluid ContaminationAir, water, solvent,and other foreign fluids are in the class of fluid contaminants.AIR CONTAMINATION.—Hydraulic fluids are adversely affected by dissolved, entrained, or free air. Air may be introduced through improper maintenance or as a result of system design. Any maintenance operation that involves breaking into the hydraulic system, such as disconnecting or removing a line or component will invariably result in some air being introduced into the system. This source of air can and must be minimized by prebilling replacement components with new filtered fluid prior to their installation. Failing to prefill a filter element bowl with fluid is a good example of how air can be introduced into the system. Although prebilling will minimize introduction of air, it is still important to vent the system where venting is possible.Most hydraulic systems have built-in sources of air. Leaky seals in gas-pressurized accumulators and reservoirs can feed gas into a system faster than it can be removed, even with the best of maintenance. Another lesser known but major source of air is air that is sucked into the system past actuator piston rod seals. This usually occurs when the piston rod is stroked by some external means while the actuator itself is not pressurized.WATER CONTAMINATION.—Water is a serious contaminant of hydraulic systems. Hydraulic fluids are adversely affected by dissolved, emulsified, or free water. Water contamination may result in the formation of ice, which impedes the operation of valves,actuators, and other moving parts. Water can also cause the formation of oxidation products and corrosion of metallic surfaces.SOLVENT CONTAMINATION.—Solvent contamination is a special form of foreign fluid contamination in which the original contaminating substance is a chlorinated solvent. Chlorinated solvents or their residues may, when introduced into a hydraulic system, react with any water present to form highly corrosive acids.Chlorinated solvents, when allowed to combine with minute amounts of water often found in operating hydraulic systems, change chemically into hydrochloric acids. These acids then attack internal metallic surfaces in the system, particularly those that are ferrous, and produce a severe rust-like corrosion. NA V AIR 01-1A-17 and NSTM, chapter 556, contain tables of solvents for use in hydraulic maintenance.FOREIGN-FLUIDS CONTAMINATION.—Hydraulic systems can be seriously contaminated by foreign fluids other than water and chlorinated solvents. This type of contamination is generally a result of lube oil, engine fuel, or incorrect hydraulic fluid being introduced inadvertently into the system during servicing. The effects of such contamination depend on the contaminant, the amount in the system, and how long it has been present.NOTE: It is extremely important that the different types of hydraulic fluids are not mixed in one system. If different type hydraulic fluids are mixed, the characteristics of the fluid required for a specific purpose are lost. Mixing the different types of fluids usually will result in a heavy, gummy deposit that will clog passages and require a major cleaning. In addition, seals and packing installed for use with one fluid usually are not compatible with other fluids and damage to the seals will result.ORIGIN OF CONTAMINATIONRecall that contaminants are produced from wear and chemical reactions, introduced by improper maintenance, and inadvertently introduced during servicing. These methods of contaminant introduction fall into one of the four major areas of contaminant origin.1. Particles originally contained in the system. These particles originate during the fabrication and storage of system components. Weld spatter and slag may remain in welded system components, especially in reservoirs and pipe assemblies. The presence is minimized by proper design. For example, seam-welded overlapping joints are preferred, and arc welding of open sections is usually avoided. Hidden passages in valve bodies, inaccessible to sand blasting or other methods of cleaning, are the main source of introduction of core sand. Even the most carefully designed and cleaned castings will almost invariably free some sand particles under the action of hydraulic pressure. Rubber hose assemblies always contain some loose particles. Most of these particles can be removed by flushing the hose before installation;。
200t液压机液压系统设计英文文献
HydraulicHydraulic systemA complete hydraulic system consists of five parts, namely, power components, the implementation of components, control components, auxiliary parts and hydraulic oil.The role of dynamic components of the original motive fluid into mechanical energy to the pressure that the hydraulic system of pumps, it is to power the entire hydraulic system. The structure of the form of hydraulic pump gears are generally pump, vane pump and piston pump.Implementation of components (such as hydraulic cylinders and hydraulic motors) which is the pressure of the liquid can be converted to mechanical energy to drive the load for a straight line reciprocating movement or rotational movement.Control components (that is,the various hydraulic valves) in the hydraulic system to control and regulate the pressure of liquid,flow rate and direction. According to the different control functions, hydraulic valves can be divided into the village of force control valve, flow control valves and directional control valve. Pressure control valves are divided into benefits flow valve (safety valve), pressure relief valve, sequence valve, pressure relays, etc.; flow control valves including throttle, adjusting the valves, flow diversion valve sets, etc.; directional control valve includes a one-way valve, one-way fluid control valve, shuttle valve, valve and so on. Under the control of different ways, can be divided into the hydraulic valve control switch valve, control valve and set the value of the ratio control valve.Auxiliary components, including fuel tanks, oil filters, tubing and pipe joints, seals, pressure gauge, oil level, such as oil dollars.Hydraulic oil in the hydraulic system is the work of the energy transfer medium, there are a variety of mineral oil, emulsion oil hydraulic molding Hop categories.Hydraulic principleIt consists of two cylinders of different sizes and composition of fluid in the fluid full of water or oil. Water is called"hydraulic press"; the said oil-filled"hydraulic machine."Each of the two liquid a sliding piston, if the increase in the small piston on the pressure of a certain value, according to Pascal's law, small piston to the pressure of the pressure through the liquid passed to the large piston, piston top will go a long way to go. Based cross-sectional area of the small piston is S1, plus a small piston in the downward pressure on the F1. Thus, a small piston on the liquid pressure to P=F1/SI, Can be the same size in all directions to the transmission of liquid." By the large piston is also equivalent to the inevitable pressure the large piston is the cross-sectional area S2, the pressure P on the piston in the upward pressure generated F2=P×S2 Cross-sectional area is a small multiple of the piston cross-sectional area. From the type known to add in a small piston of a smaller force, the piston will be in great force, for which the hydraulic machine used to suppress plywood, oil, extract heavy objects, such as forging steel.History of the development of hydraulicHydraulic and air pressure drive hydraulic fluid as the transmission is made according to the 17th century, Pascal's principle of hydrostatic pressure to drive the development of an emerging technology, the United Kingdom in 1795 Joseph (Joseph Braman,1749-1814), in London wateras a medium to form hydraulic press used in industry, the birth of the world's first hydraulic press. Media work in 1905 will be replaced by oil-water and further improved.World War I (1914-1918) after the extensive application of hydraulic transmission, especially after 1920, more rapid development. Hydraulic components in the late 19th century about the early 20th century, 20 years, only started to enter the formal phase of industrial production. 1925 Vickers (F·Vikers) the invention of the pressure balanced vane pump, hydraulic components for the modern industrial or hydraulic transmission of the gradual establishment of the foundation. The early 20th century Constantine (G·Constantimsco) fluctuations of the energy carried out by passing theoretical and practical research;in 1910 on the hydraulic transmission (hydraulic coupling, hydraulic torque converter, etc.) contributions, so that these two areas of development.The Second World War (1941-1945) period, in the United States 30% of machine tool applications in the hydraulic transmission. It should be noted that the development of hydraulic transmission in Japan than Europe and the United States and other countries for nearly 20 years later. Before and after in 1955, the rapid development of Japan's hydraulic drive, set up in 1956, "Hydraulic Industry." Nearly 20 to 30 years, the development of Japan's fast hydraulic transmission, a world leader.Hydraulic transmission applicationThere are many outstanding advantages, it is widely used, such as general workers. Plastic processing industry, machinery, pressure machinery, machine tools, etc.; operating machinery engineering machinery, construction machinery, agricultural machinery, automobiles, etc.; iron and steel industry metallurgical machinery, lifting equipment,such as roller adjustment device; civil water projects with flood control the dam gates and devices, bed lifts installations, bridges and other manipulation of institutions; speed turbine power plant installations, nuclear power plants, etc.; ship deck crane (winch), the bow doors, bulkhead valves, such as the stern thruster; special antenna technology giant with control devices, measurement buoys, movements such as rotating stage; military-industrial control devices used in artillery, ship anti-rolling devices, aircraft simulation, aircraft retractable landing gear and rudder control devices and other devices.液压液压系统一个完整的液压系统由五个部分组成，即动力元件、执行元件、控制元件、辅助元件和液压油。
外文翻译--Komatsu先进的液压系统
毕业设计(论文)外文资料翻译学院(系)：机械工程学院专业：机械工程及自动化姓名：学号：外文出处：Manufacturing Engineering (用外文写)and Technology-Machining附件： 1.外文资料翻译译文；2.外文原文。
指导教师评语：此翻译文章简单介绍Komatsu先进的液压系统，并详细介绍了先进的液压传动装置，并对计算机控制的自动变速系统进行了详细的描述，翻译用词比较准确，文笔也较为通顺，为在以后工作中接触英文资料打下了基础。
签名：年月日附件1：外文资料翻译译文Komatsu先进的液压系统操作舒适，生产能力大人性化设计的驾驶室——既宽敞又实用。
宽大的有色玻璃窗给操作员极大的视线。
带扶手五挡调节座椅，短行程手摇杆，上位开启前窗和带杠杆的驾驶用的脚踏板，所有这些都起到有助于操作员最大限度地提高产量的作用。
操作噪声低——这完全是因为有先进的OLSS液压系统以及封闭式发动机室和具有橡胶支垫的发动机。
所有这一切都有助于降低驾驶室的噪声。
手控操作杆——使得施工设备的操作轻而易举。
安装在扶手上的手控操作杆最大行程仅为65mm(2.6in),KOMATSU比例压力控制操作系统能减少准确控制施工设备所需的操作强度。
回转制动装置——即使推土机停泊在坡路上也能自动防止液压漂移。
操作员不再需要在施工设备作业的过程中用手握住制动装置。
此外，回转控制装备还配置有封闭式滑阀，以便顺利的启动和停止。
行驶/驾驶控制装置——脚踏板控制装置配有可拆卸的控制杆。
两者可根据实际运用和操作员的偏爱加以选择使用。
支垫机构——在臂缸悬臂首端、铲斗缸和底部卸料缸中，能消减液压缸伸展和收缩引起的震动，从而增加操作的舒适性，延长部件的寿命。
燃耗最低两种模式选择系统，挖掘效率高——模式选择开关可选定泵驱动功率的两种模式：S（标准模式）或（轻负荷模式）。
当需要大功率挖掘时，选择标准模式；当挖掘机用来运送轻材料或平地时，选择轻负载模式。
文献翻译-液压系统
翻译部分英文原文：HYDRAULIC SYSTEMHydraulic systems are power-transmitting assemblies employing pressurized liquid to transmit energy from an energy-generating source to an energy-use area. All hydraulic systems depend on Pascal’s law, named after Blaise Pascal, who discovered the law. This law states that pressurized fluid within a closed container-such as cylinder or pipe-exerts equal force on all of the surfaces of the container.In actual hydraulic systems, Pascal’s law defines the basis of the results which are obtained from the system. Thus, a pump moves the liquid in the system. The intake of the pumps connected to a liquid source, usually called the tank or reservoir. Atmospheric pressure, pressing on the liquid in the reservoir, forces the liquid into the pump. When the pump operates, it forces liquid from the tank into the discharge pipe at a suitable pressure.The flow of the pressurized liquid discharged by the pump is controlled by valves. Three control functions are used in most hydraulic systems: (1) control of the liquid pressure, (2) control of the liquid flow rate, and (3) control of the direction of flow of the liquid.The liquid discharged by the pump in a fluid-power system is directed by valves to a hydraulic motor. A hydraulic motor develops rotary force and motion, using the pressurized liquid as its energy source. Many hydraulic motors are similar to pumps, except that the motor operates in a reverse manner from a pump.Where linear instead of rotary motion is desired, a cylindrical tube fitted with a movable piston, called a hydraulic cylinder, is often used. When the piston is moved by the pressurized fluid, the piston rod imparts a force or moves an object through a desired distance.Restricting the movement of the piston in a hydraulic cylinder, as when the piston carries a load, creates a specific pressure relationship within the cylinder. The surface area of the piston face is said to contain a specific number of square inches. The pressure of the pressurized liquid, multiplied by the piton area, produces an output force, measured in pound, at the end of the piston rod.The speed of movement of the piston rod depends on how fast the pressurized fluid enters the cylinder. Flow into the cylinder can be directed to either end, producing either a pushing or pulling force at the piston rod end. A seal around the rodwhere it passes through the cylinder end prevents leakage of the liquid.Directional control of the piston depends on which end of cylinder the liquid enters. As pressurized liquid enters one end of the cylinder, liquid must be drained from the other end. The drained liquid is led back to the reservoir. In a pneumatic system using air, the air in the exhausting end of the cylinder is vented to the atmosphere.Directional-control valves, also called two-way, three-way, four-way, etc. , are named in accordance with their basic function. Pressure-control and simple restrictor valves are usually two-way valves. They provide ON or OFF service. A three-way valves may perform several functions, all associated with the three-ports in the valve. For example, the power or pressurized liquid from a pump in a tractor may be sent to the hydraulic system serving the tractor’s front-end loader. Or the three-way valve may send the pressurized liquid to a hydraulic motor driving a feed conveyor while the front-end loader is not being used.Three-way valves may also be used to direct pressurized fluid to a single-acting hydraulic cylinder. As the three-way valve is actuated (operated) it can stop the pressurized flow to the cylinder. Further, the same valve can divert liquid from the cylinder to the reservoir, so the cylinder can retract by gravity or return springs and assume its original position.A four-way valve has four ports or openings. The pressure port directs fluid flow to an area where pressurized liquid is desired. One of the other ports can simultaneously drain liquid from a pressurized area. The dram liquid can be directed to the reservoir.In a fluid-power system, the movement of pressurized fluid resembles the action of electric current in an electrical system. In such a system, electrical energy is continually moving when work is being done. The same is true of a fluid-power system.In a direct-current electrical system, the speed of a device is varied by changing the flow of current to the device. Alternating-current system, use phase shifting to attain similar speed control. Hydraulic system can obtain infinite speed variations by several methods of control, Pneumatic systems, because of the springiness of the gas, have relatively crude speed control.In fluid-power systems, the pump can be designed so the discharge flow of the pressurized liquid can be varied by manipulating the pump mechanism, giving varying speeds of the hydraulic motor or other output device. A restriction un the pump outlet can limit the fluid in a manner similar to that used in a direct-current electrical system. Where desired, hydraulic systems can be designed to use valves which divert flow to different flow channels to give the desired speed control.The compressibility of hydraulic fluid is slight. But, if desired, this slight compressibility can be used to absorb small, erratic machine movements which cause pressure variations in a fluid-power system. Pneumatic systems have this capability inherently because of the springiness of the air or gas used in the system. Hydraulic systems may use one or more accumulators-devices which contain pressurized gas which can accommodate rapid pressure changes in the fluid portion of the system.Gravity, springs and compressed gases provide potential energy I many hydraulic systems. Thus, gravity assist is often used to return a part to its original position without the use of power from the hydraulic system. This type of assistance also simplifies the parts in the hydraulic system.Pumps Mechanical seal Measures.At present the mechanical seal in pumps in a kind of product the application extremely widespread, but and will save the energy along with the product technical level enhancement the request, the mechanical seal application prospect is more widespread. The mechanical seal seal effect directly will affect the entire machine movement, in particular in petroleum chemical industry domain, because will exist flammable, explosive, is easy to volatilize, to be violently poisonous and so on the medium.The mechanical seal appears will divulge, seriously will affect the production normally to carry on, is serious also appears the significant security accident. People when analysis quality breakdown reason, often is familiar with in the mechanical seal own aspect searches the reason, for example: Mechanical seal shaping whether appropriate, choice of material whether correct, the packing surface compared to presses whether correctly, rubs the vice- choice is whether reasonable and so on. But is short very much in the mechanical seal external condition aspect searches the reason, for example: Pumps for the mechanical seal creation condition whether appropriate, the servosystem disposition is whether appropriate, but these aspects reasons often are count for much.This article author from pumped has analyzed the reasonable measure with the mechanical seal external condition angle which the influence seal effect several kind of factors and should adopt.1 Principle and request that machinery seals off:The mechanical seal is depends on a pair of relative motion link end surface A (fixed, another revolves together with axis) the mutual fitting forms the small axial play plays the seal role, this kind of equipment is called the mechanical seal. The mechanical seal usually by moves the link, the static link, contracts the part and the seal part is composed. Moves the link and the static link end surface composes a pair to rub, moves the link to depend on in the sealed chamber the liquid pressure to cause its shoulder up on the static link end surface, and produces on two links end surfaces suitable compared to presses and maintains an extremely thin liquid membrane toachieve the seal the goal. Contracts the part pressurize, may cause to pump under the operating condition, also maintains the end surface fitting, guaranteed the seal medium nothing more than leaks, and prevented the impurity enters seals the end surface. Seals the part to play the seal to move the link and axis gap B, the static link and the gland gap C role, simultaneously to the vibration which pumps, attacks the cushioning effect. The mechanical seal in the actual movement is not an isolated part, it is with other spare parts which pumps combines the movement together, simultaneously may see through its basic principle, the mechanical seal normal operation has the condition, for instance: Otherwise fleeing measures a pump spindle's being not able to very big, friction subsidiary end face can not form the ratio pressure demanding regularly; The pump spindle that machinery hermetic sealing gets along can not have boundary very big deflection , end face waits a minute otherwise than pressure will be uneven. Besides only when satisfying similar such external condition, fine machinery seals off oneself function, ability reaches ideal hermetic sealing effect.2 Analysis of causes that external condition affects:Pump spindle axial to fleeing is measured big: The hermetic sealing that machinery seals off needs to have certain ratio pressure face to face, such ability plays arrive at hermetic sealing role, be requiring that spring that machinery seals off needs to have certain compression amounts right now, give a propulsive force sealing off end face, rotating makes hermetic sealing produce the pressure sealing off the what be demanded ratio face to face. For ensuring that this one is compared to pressure, the amounts machinery is sealed off requiring that the pump spindle can not have very big fleeing, need to ensure that within 0.5 mm in general. Design but middle in reality, unreasonable because of design, that sometimes, very big fleeing of pump spindle creation measure , seal off to machinery sigmatism is very disadvantageous. This phenomenon sometimes appears in multi-level centrifugal pump, Especially in the process of pump starting, flee amounts are comparatively big.The automation changes the b balancing a set and balancing the axial gap between the ring when balance plate works , changes the difference balancing the pressure checking front and back two flanks thereby , produces one and comes to balance the axial force axial contrary force direction acting force. The inertia effect moving since the rotator flees and transient pump working condition fluctuation, the rotator moving round will not be motionless in some one axial balance location.Balance the state fleeing all the time in retinue to move. But the amounts balancing axial to fleeing in checking in regular job only have 0105 ~ 011 mm , satisfy permission axial to fleeing that machinery seals off measuring 015 mm requests, allowable machinery hermetic sealing axial to fleeing balancing axial to fleeing to measure possibility getting it in gear, when stopping machine , working condition great change in pump making ringsround expects that.After pumps passes through the long time movement, the friction balancing a set and balancing a ring wears away , gap b enhances subsequently, the amounts sealing off axial to fleeing increase machinery unceasingly. Effect because of axial force, hermetic sealing compacting soft and floury sucking oblique tones in increases by strenuously , hermetic sealing wears the effect aggravating , sealing up completely until hermetic sealing damages , loses face to face away face to face.The machinery spitting out oblique tones is sealed off , is wear away with balancing plate's, rotator component axial to fleeing measures the amounts sealing off axial to fleeing demanding greater than , the force sealing off compacting soft and floury is diminished , cannot reach the effect sealing off a request , making the machinery hermetic sealing on both side of the pump all ultimately losing hermetic sealing.The axial force is prejudiced big: Machinery hermetic sealing can bear the axial force's in the process of usage, if the effect that existence seals off axial the force , to machinery is grave. Since pump axial the aspect cause such as rational and making , assembling , being put into use that dynamic balance organization designs, brings about the axial force be not balanced away sometimes.Machinery hermetic sealing bears a axial force , the seal gland temperature will be partial to height when moving round, to the medium that polypropylene is similar to, before the high temperature be able to be molten down, the pump starts the queen therefore losing hermetic sealing effect very quickly right away , discontinuous gushing sealing off end face then appearing leaves out phenomenon when the pump is motionless.pump spindles deflections are slanting big: That machinery hermetic sealing calls end face hermetic sealing, is that one kind of axis of rotation to contact-type moves hermetic sealing , it is under fluid medium and elasticity component effect , two perpendicularities reach hermetic sealing effect thereby in stick the small side door , relative rapid and intense axle centre line hermetic sealing end face revolution, demands to need to accept a force homogeneously between two hermetic sealing therefore.The machinery spitting out oblique tones is sealed off , is wear away with balancing plate's, rotator component axial to fleeing measures the amounts sealing off axial to fleeing demanding greater than , the force sealing off compacting soft and floury is diminished , cannot reach the effect sealing off a request , making the machinery hermetic sealing on both side of the pump all ultimately losing hermetic sealing.not assisting irrigation system or assists irrigation system to interpose block of wood reasonableness: That assisting that machinery seals off washes system is very important , it can protect effects such as sealing off face , getting to the cooling , lubrication , washing away varia effectively. Design that allocation assists irrigation system, to be unable to reach hermetic sealing effect not rationally sometimes;Haveforeign substance sometimes although designing that the personnel has designed auxiliary system, since in washing liquid, rate of flow , pressure washing liquid are insufficient , wash mouth location designing that wait for cause unreasonable , also same being unable to reach hermetic sealing effect.vibration is slanting big: Machinery seals off vibration insisting to lead to big , ultimate losing hermetic sealing effect. That machinery seals off big slanting vibration cause sometimes is not that machinery seals off self cause but , other pump component and part is to produce the origin vibrating , waits for cause if the pump spindle designs that cause , axle bearing accuracy unreasonable , processing are insufficient , shaft coupling degree difference , radial force of equal rank are big.Cause that the pump vapor erodes: The function is not good , the pump rotation rate is partial to height since device system operation is unreasonable and the pump entrance vapor erodes, that the vapor erodes , the vapor erodes the entry occurrence part in the pump the day afer tomorrow happened , is able to have air bubble in the water, that it may pound machinery on one hand seals off the outside surface soft and floury , makes it's surface damage appear on; That another aspect may make fitting that astiring sound is encircled by also contain air bubble in flow soft and floury film, can not form the stable flow film , brings about the trunk friction that fitting that astiring sound is encircled by face , makes machinery seal damage.Machine work accuracy is insufficient: Machine work accuracy is insufficient , cause has many, the treating accuracy having plenty of machinery sealing self off is insufficient , this aspect cause finds also easy to pay attention to easy to arouse people. But the sometimes is a pump other component treating accuracy lack , this aspect cause, do not pay attention to easy to arouse people. For instance: Cause such as pump spindle , axle sleeve , the pump body , the accuracy lack sealing off enlarging of the cavity body. The hermetic sealing effect that these cause existence seals off to machinery is very disadvantageous.responds to the measure adopting:Remove a pump spindle fleeing to measure big measure:Amounts designing that axial force balance is equipped with , removes axial to fleeing rationally. For satisfying this one request,have two to the multi-level centrifugal pump , the comparatively ideal design plan: One is that balance plate adds axial to stopping push axle bearing , balance the axial force from balance plate , carry out axial on the pump spindle from axial to stopping pushing axle bearing position-limit; Another is that the balance drum adds axial to stopping push axle bearing, axial force balancing away major part from the balance drum, axial surplus force bears from stopping pushing axle bearing , axial to stopping pushing axle bearing carries out axial on the pump spindle at the same time position-limit. Second kinds schemes key is to design the balance drum rationally, makes that be able tobalance away the most axial force really. Wait for a product to opening a pump in other single stage pump,within amounts range sealing off range demanded by in machinery designing fleeing adopting a few measure guarantee pump spindles now and then.Remove big axial strenuously prejudiced measure:The organization designing axial dynamic balance rationally, makes that be able to balance away the axial force really sufficiently , being sealed up completely by machinery creates a favorable condition. Must achieve testing detecting and discovering problem and solve a problem before the product , unfinished products leave the factory to importance that fields such as a little electric power plant , petrochemical industry, applies. Some important pumps can design a axial to measuring the force ring on the rotator , monitor at any time to being on the march toward the force size scroll, discover a problem in time solve.Remove big prejudiced pump spindle deflection measure:Existence is in this phenomenon mostly in multi-level centrifugal pump of horizontal type, adopting the following measure time design:(1) cuts down both ends distance between axle bearing. The pump impeller progression is not very more than , under the general pump lift request is comparatively good situation, try one's best to improve every level impeller lift, cuts down progression;(2) increases the pump spindle diameter. During the period of the diameter designinga pump spindle, consider the size transferring power simplely only, do not but want the inertia factors such as load , radial force thinking that machinery seals off ,the axis deflection, starts method and being connected with. Much one point designing that not sufficient cognition arrives at this;(3) improves pump spindle material grade;(4) pump spindles are designed after being completed, the deflection to the pump spindle asks the checkout carrying out the core of school to secretly scheme against. Increases by assisting irrigation system:Under the situation that condition allows, system designing auxiliary irrigation to the full. Wash pressure general requirements overtoping 0107 ~ 011 MPa sealing off cavity pressure, if transportation medium belongs to easy vaporization, respond to 01175 ~ 012 MPa higher than vaporization pressure then. The pressure sealing off a cavity is going to secretly scheme against according to every kind of pump structure during the past factors such as pattern , system pressure.Or when shaft seal accent pressure is very high when pressure uses almost approximation should seal up completely the maximal limit, fever of also may make shaft seal liquid be on the move from the area sealing off a cavity attracting liquid till low pressure, to take away friction. If the irrigation amounts being recommended by administering medicine to bring out the cold be what 1 shows. According to each kind of pump operation condition,deploy the pipeline andaccessories rationally. If the chiller , pore plate , filter , valve , rate of flow indicator , piezometer , the temperature wait. Reliability and life-span sealing up completely in fact, depend on the allocation sealing off auxiliary system's to a great extent. Remove the measure that the pump entrance vapor erodes:(1) The vapor eclipse function raising a pump is horizontal , the vapor satisfying the scene device erodes the function request;(2) Scene tester request needs and the pump vapor erodes function level matching;(3) That scene installation and working condition adjustment need to give a pump creates advantageous condition.3.6 Remove the measure that the pump shakes:(1) The product is hit by a pump in designing process , is is going to analyse the source vibrating sufficiently, to eliminate shaking a source. ;(2) Pump product fabrication assembles process middle , directive rules goes and carrying out , eliminates shaking a source strictly according to the standard and operation;(3) Pump , electric motor , assist equipment to be going to guard the pass , eliminate strictly to shake a source during the period of scene installation such as base , scene pipeline,;(4) Guard the pass , eliminate when producing , handling , keeping a scene in repair , adjusting, strictly to shake a source. Execute to the letter design criterion:The design sealing off a product's asks pump product design and machinery to carry out the pertinent home and abroad standard , design that should carry out a standard carefully in the process of the product design,among deep every strip content concrete significance understanding a standard , the process the standard content request implementation is designed to the product.By now, actual import having many standards designing that not understand that , go and carrying out the new standard, not but being to copy the experience designing according to the set of old drawing sheet and old people blind strictly. That this resorts to magic arts to improving our country product engineering level and entering international market is very disadvantageous. Improve the standardizing cognition , be that machinery industry designs that need the problem solving urgently at present.Pumps when the design with the mechanical seal, not only must consider the mechanical seal itself influence factor, moreover must consider exterior the mechanical seal each kind of influence factor. Must pay attention to following several questions in the practical work:(1) in pumps the product in the design process to have fully to consider pumps other spare parts as well as the scene other equipment to the mechanical seal use effect influence, creates a good external condition for the mechanical seal;(2) increases to the mechanical seal servosystem vital role understanding, provides the consummation as far as possible the mechanical seal servosystem, enhances the seal effect;(3) to importantly pumps the product the mechanical seal, must increase the protective measures, improves the seal quality, reduces the seal quality accident;(4) analyzes the mechanical seal the quality accident reason, must fully consider pumps other spare parts to the mechanical seal movement influence, take the measure unceasingly to enhance the mechanical seal the effect.The bolt pump has because of the person but variable transportation , self attract ability characteristics such as strong , may become worse , being able to transport the liquid containing a solid particle, in sewage treatment factory, be put into use broadly cover in the field of the drug-dip transporting water , wet sludge and flocculant. The bolt pump selects and uses should abide by economy , rational , reliable principle. If doing not think out in the field of the type designing selections, be able to give hereafter sigmatism, to management , be maintained bring about inconvenient , need according to producing reality therefore selecting and using one, now that the rational reliable bolt pump being able to swear to give birth to a child proceeding as planned and without a hitch, reduce mending cost.中文译文：液压系统液压系统是利用液体为介质把能量从动力源传递到消耗位置的动力传递系统。
《外文文献翻译-液压系统》
液压系统一个完整的液压系统由五个部分组成，即动力元件、执行元件、控制元件、无件和液压油。
动力元件的作用是将原动机的机械能转换成液体的压力能，指液压系统中的油泵，它向整个液压系统提供动力。
液压泵的结构形式一般有齿轮泵、叶片泵和柱塞泵。
执行元件(如液压缸和液压马达)的作用是将液体的压力能转换为机械能，驱动负载作直线往复运动或回转运动。
控制元件(即各种液压阀)在液压系统中控制和调节液体的压力、流量和方向。
根据控制功能的不同，液压阀可分为村力控制阀、流量控制阀和方向控制阀。
压力控制阀又分为益流阀(安全阀)、减压阀、顺序阀、压力继电器等；流量控制阀包括节流阀、调整阀、分流集流阀等；方向控制阀包括单向阀、液控单向阀、梭阀、换向阀等。
根据控制方式不同，液压阀可分为开关式控制阀、定值控制阀和比例控制阀。
辅助元件包括油箱、滤油器、油管及管接头、密封圈、压力表、油位油温计等。
液压油是液压系统中传递能量的工作介质，有各种矿物油、乳化液和合成型液压油等几大类。
液压的原理它是由两个大小不同的液缸组成的，在液缸里充满水或油。
充水的叫“水压机”；充油的称“油压机”。
两个液缸里各有一个可以滑动的活塞，如果在小活塞上加一定值的压力，根据帕斯卡定律，小活塞将这一压力通过液体的压强传递给大活塞，将大活塞顶上去。
设小活塞的横截面积是S1，加在小活塞上的向下的压力是F1。
于是，小活塞对液体的压强为P=F1/SI, 能够大小不变地被液体向各个方向传递”。
大活塞所受到的压强必然也等于P。
若大活塞的横截面积是S2，压强P在大活塞上所产生的向上的压力F2=PxS2 ，截面积是小活塞横截面积的倍数。
从上式知，在小活塞上加一较小的力，则在大活塞上会得到很大的力，为此用液压机来压制胶合板、榨油、提取重物、锻压钢材等。
液压传动的发展史液压传动和气压传动称为流体传动，是根据17世纪帕斯卡提出的液体静压力传动原理而发展起来的一门新兴技术，1795年英国约瑟夫•布拉曼(Joseph Braman,1749-1814)，在伦敦用水作为工作介质,以水压机的形式将其应用于工业上,诞生了世界上第一台水压机。
液压系统设计外文文献翻译
附录AHydraulic systemC.J.Sexton,S.M.LewisandC.P.PleaseUniversity of Southampton,UKAbstract:A complete hydraulic system consists of five parts, namely, power components, actuators, control components, auxiliary components (accessories) and hydraulic oil. The function of hydraulic system is to help human work, mainly through the implementation of components into the pressure of rotation or reciprocating movement. Other advantages of the hydraulic system include bi-directional movement, overload protection, and variable speed control. In any of the existing powertrain systems, the hydraulic system also has the largest unit mass power ratio. Seals and seals are an important part of hydraulic equipment. Its reliability and service life is an important index to measure the quality of hydraulic system.Keywords: A power element; an actuating element; a control element; an auxiliary element; hydraulic fluidGenerally, there are only three basic ways to transmit power: electrical, mechanical, and hydraulic. Most applications actually combine the three methods into the most efficient and comprehensive system. In order to reasonably determine which method to take, it is important to understand the salient features of the various methods. For example, the hydraulic system transmits power more economically over a long distance than a mechanical system. The hydraulic system, however, has a shorter transmission distance than the electrical system.Hydraulic transmission there are many outstanding advantages, it is widely used, such as the general industrial use of plastics processing machinery, pressure machinery, engineering machinery, machine tools and other mechanical equipment; application of construction machinery, agricultural machinery, automobile and other metallurgical machinery; iron and steel industry, lifting machinery, a roller adjustment device; control gate device in the water conservancy project, riverbed lifting device, bridges and other operating mechanism; high speed turbine power plant equipment, such as nuclear powerplants; ship deck with crane (winch), bow door, bulkhead valve stern thruster; special technology giant antenna with control devices measurement buoys movements such as rotating stage; military industrial control devices used in artillery ship anti rolling devicesaircraft simulation aircraft retractable landing gear and rudder control device device. Special antenna technology control device, measuring buoy, lifting and rotating stage; military artillery unit, ship antirolling device, flight simulation, device and other equipment for rudder control of landing gear and steering device.The function of hydraulic system is to increase the force by changing the pressure. The quality of a hydraulic system depends on the rationality of the system design, the performance of the system components, the pollution prevention and treatment of the system, and the last point is particularly important. In recent years, China's domestic hydraulic technology has greatly improved, and no longer only the use of foreign hydraulic technology for processing.A complete hydraulic system consists of five parts, namely, power components, actuators, control components, auxiliary components (accessories) and hydraulic oil.The function of the power element is to convert the mechanical energy of the prime mover into the pressure energy of the liquid, the oil pump in the hydraulic system, which provides power to the entire hydraulic system. The structure of hydraulic pumps usually include gear pumps, vane pumps and piston pumps.The actuating elements (such as hydraulic cylinders and hydraulic motors) are used to convert the pressure energy of the fluid into mechanical energy and to drive the load in linear reciprocating or slewing motion.Control elements (i.e. hydraulic valves) control and regulate the pressure, flow, and direction of the liquid in the hydraulic system. According to different control functions, the hydraulic valve can be divided into pressure control valve, flow control valve and directional control valve. Pressure control valves are divided into benefits flow valve (An Quanfa), pressure relief valve, sequence valve, pressure relays etc.; flow control valves including throttle valve, regulating valve, diversion valve; directional control valve includes a one-way valve one-way fluid control valve, shuttle valve, reversing valve, etc.. According to different control methods, the hydraulic valve can be divided into switching control valve, fixed value control valve and proportional control valve.The auxiliary components include oil tank, oil filter, oil pipe and pipe joint, sealing ring, quick change joint, high pressure ball valve, hose assembly, pressure measuring joint, pressure gauge, oil level, oil temperature gauge and so on.Hydraulic oil is the medium of transmission of energy in hydraulic system. There are several kinds of mineral oil, emulsion and synthetic hydraulic oil.The function of hydraulic system is to help human work, mainly throughthe implementation of components into the pressure of rotation or reciprocating movement. Hydraulic principle: it is composed of two different sizes of the cylinder is filled with water or oil. Full of water, known as "hydraulic press", full of oil known as "hydraulic press."". Each of two hydraulic cylinders have a movable piston, if put in the small piston on the pressure, according to Pascal's law, the small piston pressure to the piston through the pressure of liquid, the top of the piston will move long distances. The cross-sectional area of the basic small piston is S1, plus a small piston with a downward force F1. Thus, the pressure on the liquid of the small piston, P=F1/S1, can be transmitted equally in all directions. The pressure through the big piston is also P. If the cross sectional area of the piston is S2, pressure F2=P*S2 P pressure piston upward, the cross-sectional area of the small piston is several times, in addition to the small piston small piston force, there will be great pressure, the hydraulic press for pressing plywood, oil, lifting, forging steel.The secret of the hydraulic system's success and versatility lies in its versatility and ease of operation. Hydraulic power transmission will not be restricted, the geometry of the machine as a mechanical system that in addition, hydraulic system is not limited by the physical properties of materials like electrical system, it is almost no amount of power transfer limit. For example, the performance of an electromagnet by steel magnetic saturation limit, on the contrary, the power of hydraulic system only limited by material intensity.In order to increase productivity, enterprises will increasingly rely on automation, which includes remote and direct control of production operations, processing and material handling. The hydraulic power has become an important part of automation, because it has the following four main advantages:1. convenient control, accurate operation by a joystick and a simple button, the hydraulic system operator can immediately start, stop, speed and can provide arbitrary power, position accuracy of 1/10000 inches of position control. A hydraulic system that causes the pilot to lift and drop the landing gear. When the pilot moves the control valve in one direction, the pressure oil flows into a cavity of the hydraulic cylinder and thus falls.2. force, a hydraulic system without the use of heavy gear, pulley lever can simply and effectively less than an ounce of force amplification, produce hundreds of tons of force output.3. constant or constant torque, hydraulic system can not only provide constant change with speed changing or constant torque, it can drive the mobile object per hour from a few inches to several hundred inches per minute per hour. From a few to thousands of revolutions per minute.4. Simple, safe, economical, and in general, hydraulic systems use fewer moving parts than mechanical or electrical systems, so they are easy to run and maintain. This makes the system compact, safe and reliable. For example, a new type of power steering device for vehicles has been phased out of other types of steering power units, which include manual controlsDirection control valve and distributor. Because the steering component is fully hydraulic, there is no universal joint, bearings, gear reducer and other mechanical connections, which makes the system simple and compact. In addition, only very little input torque can produce control force needed to meet the extremely harsh working conditions. It is very important to the operation of space limitations and need a small steering wheel which is necessary to reduce the occasion, operator fatigue.Other advantages of the hydraulic system include bi-directional movement, overload protection, and variable speed control. In any of the existing powertrain systems, the hydraulic system also has the largest unit mass power ratio.The hydraulic system has three disadvantages:1. because the transmission medium (hydraulic oil) in the course of flow, part of the flow velocity is different, resulting in liquid friction, and at the same time, liquid and pipe wall also friction, this is the hydraulic oil temperature rise reasons. Excessive temperature results in more internal and external leakage and reduces mechanical efficiency. At the same time, the hydraulic oil will expand due to the higher temperature. Resulting in an increase in compressibility so that the operation cannot control transmission very well. Solution: high temperature is the hydraulic system's own problems, can only be the biggest mitigation, can not eradicate. The use of better quality hydraulic oil, hydraulic pipe layout, as far as possible to avoid bending, the use of high-quality pipe and pipe fittings, hydraulic valve.2. the vibration of hydraulic system is one of the weak points. The impact of hydraulic oil in the pipeline on the high speed impact and control valve opening and closing is the cause of system vibration. Strong vibrations can cause system control errors, and can cause errors in some of the more complex, sophisticated devices in the system, leading to system failures. Solution: the hydraulic pipe should be fixed, to avoid sharp bends. In order to avoid frequent flow direction changes can not be avoided, shock absorption measures should be done best. The whole hydraulic system should have good vibration reduction measures, while avoiding the influence of the oscillator outside the system.3. the hydraulic system has internal leakage and external leakage, internal leakage refers to the leakage process occurs in the system, such as leakage of hydraulic piston - cylinder, control valve spool and valve leakage between both sides, such as. Although there is no loss of hydraulic oil, but the leakage, the control action has been determined until the system failure. Disclosure refers to the leakage that occurs between the system and the external environment. Hydraulic oil leaks directly into the environment, and in addition to affecting the working environment, there is not enough power to cause system failure. Hydraulic oil leaking into the environment is also dangerous to fire. Solution: use better quality seals to improve the machining accuracy of the equipment.In hydraulic systems and systems, seals are used to prevent leakage of theworking medium and invasion of foreign dust and foreign matter. A sealed element, that is, a seal. Outside leakage will cause waste of working medium, pollute machine and environment, even cause mechanical malfunction and personal accident of equipment. Leakage can cause a drastic drop in volumetric efficiency of hydraulic systems, resulting in insufficient working pressure and even failure to perform work. The small dust particles in the invading system can cause or aggravate the wear of the friction pairs of hydraulic components, and further lead to leakage.As a result, seals and seals are an important part of hydraulic equipment. Its reliability and service life is an important index to measure the quality of hydraulic system. In addition to the clearance seal, the seal is used to control the clearance between the two adjacent surfaces to be below the minimum clearance required for the sealing liquid to pass. In contact sealing, it is divided into two types: self sealing type and self sealing type (i. e. lip seal).附录B液压系统摘要：一个完整的液压系统由五个部分组成，即动力元件、执行元件、控制元件、辅助元件（附件）和液压油。
汽车式起重机液压系统外文文献翻译中英文
外文文献翻译(含：英文原文及中文译文)文献出处：K Tanizumi. Truck Crane Hydraulic System: Technical Status and Development Trend [J]. Advanced Materials Research, 2015, 310-319中文译文汽车式起重机液压系统: 技术现状与发展趋势K Tanizumi1行业背景1.1工程汽车起重机的发展趋势近20年世界工程起重机行业发生了很大变化。
RT(越野轮胎起重机) 和AT(全地面起重机) 产品的迅速发展,打破了原有产品与市场格局,在经济发展及市场激烈竞争冲击下, 导致世界市场进一步趋向一体化。
为与RT 和AT 产品抗衡, 汽车起重机新技术、新产品也在不断发展。
近年来汽车起重机在英、美等国市场的复兴,使人们对汽车起重机产生新的认识。
几年前某些工业界人士曾预测, RT 和AT 产品的兴起将导致汽车起重机的衰退。
日本汽车起重机在世界各地日益流行,以及最近格鲁夫、特雷克斯、林克.贝尔特、德马泰克等公司汽车起重机的产品进展, 已向上述观念提出挑战。
随着工程起重机各机种间技术的相互渗透与竞争,汽车起重机会在世界市场中继续占有一席之地。
国外工程起重机从整体情况分析, 领先国内10~20年(不同类型产品有所不同) 。
随着国外经济发展速度趋于平稳,工程起重机向智能、高性能、灵活、适应性强、多功能方向发展。
25t 以下基本上不生产,产品向高附加值、大吨位发展, 住友建机、多田野和加藤公司曾于1989年相继推出360t 汽车起重机。
住友建机在90年代开发出80t ~250t 共4种AT 产品。
多田野也在90年代相继推出100t ~550t 共6种特大型AT 产品。
加藤公司则研制成NK5000型500t 汽车起重机。
行业配套也与国内有所不同:(1)下车主要是300kW 以上柴油大功率发动机,与之配套的液力变矩器和自动换档变速箱、12吨级驱动转向桥及越野轮胎。
液压英文文献翻译
Hydraulic systemChapter 1 IntroductionHydraulic Pump Station also known as the stations are independent h- ydraulic device.It requested by the oil gradually. And controlling the hydraulic oil flow direction, pressure and flow rate, applied to the mainframe and hy- draulic devices separability of hydraulic machinery.Users will be provided after the purchase hydraulic station and host of implementing agencies (motor oil or fuel tanks) connected with tubing, Hydraulic machinery can be realized from these movements and the work cycle.Hydraulic pump station is installed, Manifold or valve combination, t- anks, a combination of electrical boxes.Functional components :Pump device -- is equipped with motors and pumps, hydraulic station is the source of power. to mechanical energy into hydraulic oil pressure can be.Manifold -- from hydraulic valve body and channel assembled. Right direction for implementation of hydraulic oil, pressure and flow control.Valve portfolio -- plate valve is installed in up board after board conn-ects with the same functional IC.Tank -- plate welding semi-closed containers, also loaded with oil filtering network, air filters, used oil, oil filters and cooling.Electrical boxes -- at the two patterns. A set of external fuse terminal plate; distribution of a full range of electrical control.Hydraulic Station principle : motor driven pump rotation, which pump oil absorption from the oil tank. to mechanical energy into hydraulic pressure to the station, hydraulic oil through Manifold (or valve combinations) realized the direction, pressure, After adjusting flow pipe and external to the cylinder hydraulic machinery or motor oil, so as to control the direction of the motive fluid transformation force the size and speed the pace of promoting the various acting hydraulic machinery.1.1 Adevelopment courseChina Hydraulic (including hydraulic, the same below), pneumatic and seals industrial development process can be broadly divided into three phases, namely : 20 early 1950s to the early 1960s, the initial stage; 60's and 70 for specialized production system ;80~90's growth stage for the rapid development stage. Which, hydraulic industry in the early 1950s from the machine tool industry production of fake Su-grinder, broaching machine, copying lathe, and other hydraulic drive started, Hydraulic Components from the plant hydraulic machine shop, self-occupied. After entering the 1960s, the application of hydraulic technology from the machine gradually extended to the agricultural machinery and mechanical engineering fields, attached to the original velocity of hydraulic shop some stand out as pieces of hydraulic professional production. To the late 1960s, early 1970s, with the development of mechanized production, especially in the second automobile factory in providing efficient, automated equipment, along with the Hydraulic Components manufacturing has experienced rapid development of the situation, a group of SMEs have become professional hydraulic parts factory. 1968 China's annual output of hydraulic components have nearly 200,000 in 1973, machine tools, agricultural machinery, mechanical engineering industries, the production ofhydraulic parts factory has been the professional development of more than 100 and an annual output more than one million. an independent hydraulic manufacturing industry has begun to take shape. Then, hydraulic pieces of fake products from the Soviet Union for the introduction of the product development and technical design combining the products to the pressure, Hypertension, and the development of the electro-hydraulic servo valves and systems, hydraulic application areas further expanded. Aerodynamic than the start of the industrial hydraulic years later, in 1967 began to establish professional pneumatic components factory, Pneumatic Components only as commodity production and sales. Sealed with rubber and plastics, mechanical seals and sealing flexible graphite sealing industry, the early 1950s from the production ordinary O-rings. rubber and plastics extrusion, such as oil seal sealing and seal asbestos products start to the early 1960s, begun production of mechanical seals and flexible graphite sealing products. 1970s, the burning of the former Ministry, a Ministry, the Ministry of Agricultural Mechanization System, a group of professional production plants have been established, and the official establishment of industries to seal industrial development has laid the foundation for growth.Since the 1980s, in the country's reform and opening up policy guidelines, with the development of the machinery industry, based mainframe pieces behind the conflicts have become increasingly prominent and attracted the attention of the relevant departments. To this end, the Ministry of the original one in 1982, formed the basis of common pieces of Industry, will be scattered in the original machine tools, agricultural machinery, mechanical engineering industries centralized hydraulic, pneumatic and seals specialized factories, placing them under common management infrastructure pieces Bureau, so that the industry in the planning, investment, technology and scientific research and development in areas such as infrastructure pieces Bureau of guidance and support. Since then entered a phase of rapid development, has introduced more than 60 items of advanced technology from abroad, including more than 40 items of hydraulic, pneumatic 7. After digestion and absorption and transformation, now have mass production, and industry-leading products. In recent years, the industry increased the technological transformation efforts, in 1991, Local enterprises and the self-financing total input of about 20 billion yuan, of which more than 1.6 billion yuan Hydraulic. Through technological transformation and technology research, and a number of major enterprises to further improve the level of technology, technique and equipment to be greatly improved. In order to form a higher starting point, specialization, and run production has laid a good foundation. In recent years, many countries in the development of common ownership guidelines, under different ownership SMEs rapid rise showing great vitality. With the further opening up, three-funded enterprises rapid development of industry standards for improving and expanding exports play an important role. Today, China has and the United States, Japan, Germany and other countries famous manufacturers joint ventures or wholly-owned by foreign manufacturers to establish a piston pump / motor, planetary reduction gears, steering gear, hydraulic control valve, hydraulic system, hydrostatic transmission, hydraulic Casting. pneumatic control valve, cylinder, gas processing triple pieces, mechanical seals, rubber and seal products more than 50 production enterprises, attracting foreign investment over 200 million U.S. dollars.1.2 the current situation1.21 Basic ProfilesAfter 40 years of efforts, China hydraulic, pneumatic and sealing industry has formed a relatively complete categories. a certain level of technical capacity and the industrial system. According to the 1995 Third National Industrial Census statistics, hydraulic, Pneumatic seals and industrial 370,000 annual sales income of 100 million yuan in state-owned, village-run,private and cooperative enterprises, individual, "three capital" enterprises with a total of more than 1,300, of which about 700 hydraulic, Pneumatic seals and the approximately 300 thousand. By 1996 with the international trade statistics, the total output value of China's industry hydraulic 2.348 billion yuan, accounting for the world's 6; Pneumatic industry output 419 million yuan, accounting for world No. 10.1.22 the current supply and demand profilesThrough the introduction of technology, independent development and technological innovation, and high-pressure piston pump, gear pumps, vane pump, General Motors hydraulic valves, tanks, Non-lubricated aerodynamic pieces and various seals of the first large technology products has increased noticeably. stability of the mass production may, for various mainframe products provide a level of assurance. In addition, hydraulic and pneumatic components of the CAD system, pollution control, proportional servo technology has scored some achievements, and is already in production. Currently, hydraulic, pneumatic and seals products total about 3,000 species, more than 23,000 specifications. Among them, there are 1,200 hydraulic varieties, more than 10,000 specifications (including hydraulic products 60 varieties 500 specifications); Pneumatic are 1,350 varieties, more than 8,000 specifications; Rubber seal 350 species more than 5,000 specifications have been basically cater to the different types of mainframe products to the general needs, complete sets of equipment for major varieties of matching rate was over 60%, and started a small amount of exports.1998 pieces of homemade hydraulic output 4.8 million. sales of about 28 billion (of which about 70% mechanical systems); aerodynamic pieces yield 3.6 million. sales of about 5.5 billion (of which about 60% of mechanical systems); Seals output of about 800 million. sales of about 10 billion (of which about 50% mechanical systems). According to the China Hydraulic Pneumatic Seals Industry Association 1998 annual report, hydraulic product sales rate of 97. 5% (101% for hydraulic), pneumatic 95.9%, 98.7% sealed. This fully reflects the basic marketing convergence.My hydraulic, pneumatic and sealing industry has attained a great deal of progress, but with mainframe development needs, and the world's advanced level, there are still many gaps, mainly reflected in the product variety, performance and reliability, and so on. Hydraulic products as an example, products abroad only one-third, life for half abroad. In order to meet key mainframe, and mainframe imports of major technology and equipment needs, every year a large number of hydraulic, pneumatic and sealing products imports. According to customs statistics and the analysis of data, in 1998 hydraulic, pneumatic and seals in the import about 200 million U.S. dollars, Hydraulic which about 1.4 billion dollars, aerodynamic nearly 030 million U.S. dollars, sealed about 030 million U.S. dollars. compared with a slight decline in 1997. By sums, currently imported products on the domestic market share of about 30%. 1998 pieces of the domestic market demand for hydraulic total of about six million, the total sales of nearly 40 billion; aerodynamic pieces of the total demand of about 5 million, with sales more than 700 million yuan; Seals total demand of about 1.1 billion. total sales of about 1.3 billion.1.1the development trend of the future1.31 affect the development of the main factors(1) product development ability, and the level of technological development and speed can not completely meet the advanced mainframe products, major equipment and technology imported equipment and maintenance support;(2) the number of enterprises manufacturing technology, the level of equipment andmanagement standards are comparatively backward, coupled with a strong sense of quality, resulting in low levels of product performance, quality, Reliability poor services in a timely manner, lack of user satisfaction and trust of the brand-name products;(3) industry specialization of production low, scattered strength, low repeat serious, between regions and enterprises of convergence products, blindly compete with each other, driving down prices, the decline of enterprise returns, lack of funds, liquidity difficulties, product development and technological transformation is inadequate and seriously restricted the industry to improve the overall level of competition and the increase of strength;(4) The internationalization of the domestic market and the increasing degree of foreign companies have entered the Chinese market and participate in competition with the domestic private and cooperative enterprises, individuals, foreign-funded enterprises, such as the rise of state-owned enterprises due to the growing impact.1.32 the development trendAs the socialist market economy continues to deepen, hydraulic, pneumatic and sealing products in the market supply and demand and there is a greater change, long ago to a "shortage" of the seller's market has basically become a "structural surplus" of the characteristics of the buyer's market place . Overall capacity, is already in oversupply situation, in particular the general low level of hydraulic, pneumatic and seals, the general oversupply; and the host of urgent high-tech high-parameter, high value-added high-end products, and they do not satisfy the market needs, only dependent on imports. China joins the WTO, its impact may be even greater. Therefore, the "15" during the growth of the output value of industry, must not depend on volume growth and the industry should address the structural problems of their own, increase the intensity of the adjustment of the industrial structure and product mix, is, we should rely on the improvement of quality, and promote technical upgrading of products to meet market demand and stimulating, seek greater development.2 The application of hydraulic power sliding stage2.1 Power sliding Taiwan introducedThis paper deals with the investigation for slide unit's impact and motion stabil¬ity in modular machine tool fay means of the method of power bond graph and state space analysis. The dynamic mathematical model of self-adjusting back pressure speed control system used to drive slide unit is established. Main reasons and affect¬ing factors for slide unit impact and motion unstability are analysed through compu¬ter digital simulation, It is concluded from those that, if the structural dimensions of hydraulic cylinder and back pressure valve are designed rationally, the slide unit's dynamics will markedly be improved.NOMENCLA TURESf flow sourceSei sliding friction force in slide unitR equivalent viscous friction coefficient in slide unitIi mass of slide unit and cylinderh mass of SABP valve spoolCi,C2hydraulic capacitances of rod chamber and non-rod chamber in cylinder re-spec-tivelyC3spring compliance of SABP valveR]r R2hydraulic resistances of damping holesR9hydraulic resistance of orifice of SABP valveSe2presetting force of spring in SABP valveI4J5equivalent liquid inertia in pipe linesC^Cg equivalent hydraulic capacitances in pipe linesequivalent hydraulic resistances in pipe linesV-j V^oil-containing volumes in non-rod chamber and rod chamber respectivelyP,r:, P-i oil pressures in non-rod chamber and rod chamber respectivelyF load acted on slide unitV slide unit velocityDuring operation of modular machine tool, the changes of slid unit's speed and load acted on it in both magnitude and direction will affect working performar.ee to a different extent Particularly the impact caused by sudden vanishing of load and the motion unstability due to periodical change of load in operation will affect the surface quality of the workpiece machined, and the tool would be broken off under serious conditions, By using the method of power bond graph and state space analysis, the dynamic mathematical model of the system used to drive slide unit is established, that is called as self-adjusting back pressure speed control system and abbreviated to SABP system. In order to improve slide unit's dynamics, it is necessary to find out the main reasons and affecting factors, that must be based on computer digital simulation and study on the results.2.2 Dynamic Mathematica ModeldThe schematic diagram of SABP system is shown in Fig.l, the system is used to perform the cycle of feeding, stopping and returning. Four way control valve works in the right position during slide unit's feeding. The supply pressure of the pump is approximately constant under the action of pressure relief valve, the oil through the control valve and pressure compensated flow control valve enters the non-rod chamber to put slide unit forward. At the same time, the oil from the rod chamber is discharged through SABP valve and directional control valve to tank. In this process, the state of two check valves and pressure relief valve is not changed, To establish the mathematical model as reasonably and simply as possible, consideration must be focused on main affecting factors for a complex non-linear system such as the SABP system. It is illustrated by theoretical analysis and test result ' , that the transient time of the system is much longer than that of the flow control valve, and the flowrate overshoot of the valve in transients affects very small to slide unit speed because of the ;large effective sectional area of non-rod chamber in cylinder. For investigating the system's dynamics widely and deeply, the initial model tn is further simplified in this paper, and so the study can be efficiently made with microcomputer. It is assumed that the flowrate through the flow control valve is constant in the whole transient process, and is denoted to a flow source.Fig.2 shows the structure diagram of the dynamic model of the system, it is composed of cylinder, slide unit, SABP valve and pipe line; etc.By using the method of power bond graph and state space analysis in this paper, the dynamic mathematical model of the system is to be established- The power bondgraph is a power flow diagram, which expresses abstractly the actions among sub-systems as three effects, i.e. resistance effect, capacitive effect and inertia effect, according to the way of energy transform, on the basis of practical structure and by means of method of lumped parameters. The model is characterized by a clear con-ception in physics, and non-linear system can be accurately analysed in combination with method of state space analysis, thus it is a effective method used in the dyna mic investigation of complex non-linear system in the'timedomain.From main performances of components in SAEP system, the power bond graph of the system has been formed by means of the rule of model establishing ' and is shown in Fig.3. Half arrow in each bond indicates a direction of power How, two variahles of power are effort variable and flow variable. O-junction illustrates algebraic summation of flow variables at common effort, i.e. parallel connection, 1-junction does algebraic summation of effort variables at common flow, i.e. series connection. The symbol TF represents power transformer between two types of energy, and transforming modulus between efforts or flows is noted below the symbol TF. Short transverse bar across one end of each bond shows causality between two variables. A full arrow expresses a control action. Among three actions, there is an integration or differential form in capacitive effect and inertia effect between two variables. So state equation may be derived from Fig.3, there are nine state variables in this complex nonlinear equation. Studying on the slide unit's dynamics is started with impact and motion stability. The equation is simulated by using the method of 4th order Runge-Kutta integration procedure on IBM-PC computer. Fig.4 and Fig.5 illustrate the results respectively.2.3 Sliding front rushedSlide unit's impact phenominon results from load's vanishing in the transients, ■for example, the situation of drilling through workpiece, Fig.4 expounds the variations of the load and speed of slide unit, the pressures of chambers in cylinder. When slide unit motions evenly under the action of load, the oil pressure in non-rod chamber is very high, and there is a lot of hydraulic energy accumulated in side. The pressure decreases at once with load's discharging rapidly. During the process of oil pressure converting from high to low, the system absorbs some of the energy, so slide unit impacts forward with high speed. And then the oil in rod chamber is compressed to increase back pressure, some of the energy is consumed, which plays a part of restraining the impact of the slide unit. It must be noted that inlet pressure of SABP valve telys on the interaction of pressures of two chambers, and increases rapidly at the instant of load's vanishing, and then stabilizes at some value greater than initial one. This pressure is also greater than one of traditional speed control system, therefore the energy can be absorbed much more in the rod chamber. In result, the impact of slide unit in SABP system is 20% lawer than in traditional's. It is thus clear that slide unit with SABP system for driving has a good performance in restraining the impact and SABP valve plays an important part inthat,2.4The movement of the slide stabilityWhen load acting on slide unit varies periodically, such as the situation of milling, slide unit's speed will bring about some pulse. In order to meet the requirements of manufacturing quality, the magnitude of the speed pulse must be reduced as small as possible. The variation of the load is assumed to be of sine wave, in order to simplify discussion of the problem, The result of digital simulation is shown in Fig.5 It can be seen that, the response of the system is the sameas traditionl's and the differences between them are very small. The reason for this is that the variation of the load is not targe, there the pressures in chambers vary very little that is, the effect of the SABP valve is not obvious.2.5 Improvement measuresIt is shown by studying, that dynamics of slide unit which used SABP speed control system as driving system is better than that of traditional system. To reduce the slide unit's impact, the back pressure of rod chamber has to be increased rapidly in the transients of load's vanishing; on the other hand, to enhance the slide unit's motion stability, it is necessary to raise the system rigidity. However, main recommendation lies in decreasing the volume of oil. It is known from system structure that, there is a lot of oil-containing volume between the rod chamber and drain pipe as shown in Fig.6a. Because the volume exists, not only the effect of SABP valve is delayed and reduced, hut also the rigidity of the system is decreased. Therefore, it is hindered to further improve the impact and motion stability. To make the slide unit dynamics better, the structural dimensions of cylinder's chamber and the SABP valve must be designed suitably. Based on simulations under the various structural dimensions and comparison among the results, the following two measures can be taken for improvements:The ratio between volumeV4 and V3 is changed from 5.5 to 1 approximately, as shown in Fig,6b;the bottom diameter of spool of the SABP valve is increased from 10 mm to 13 mm and the length of side of triangular damping slot is decreased from 1 mm to 0.7mm the slide unites impact quantity can be reduced by 30%, and the time of dynamic response is shortened. In addition, slide unit's motion stability may be improved obviously. It is thus evident that improvements are very effective.液压系统1绪论液压站又称液压泵站，是独立的液压装置。
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毕业设计（论文）外文文献翻译译文题目 Hydraulic System专 业机械设计制造及其自动化 班 级 09机制一班 姓 名 汪康 学 号 ************* 指导教师 王霞机械工程学院JINGCHU UNIVERSITY OF TECHNOLOGYHydraulic SystemThere are only three basic methods of transmitting power：Electrical，mechanical．and fluid power．Most applications actually use a combination of the three methods to obtain the most efficient overall system．To properly determine which principle method to use。
it is important to know the salient features of each type．For example，fluid systems call transmit power more economically Over greater distances than Can mechanical types．However。
fluid systems are restricted to shorter distances than are electrical systems．Hydraulic transmission there are many outstanding advantages, it is widely used, such as general industrial use of plastics processing machinery, the pressure of machinery, machine tools, etc.; operating machinery engineering machinery, construction machinery, agricultural machinery, automobiles, etc.; iron and steel industry metallurgical machinery, lifting equipment, such as roller adjustment device; civil water projects with flood control and dam gate devices, bed lifts installations, bridges and other manipulation of institutions; speed turbine power plant installations, nuclear power plants, etc.; ship from the deck heavy machinery (winch), the bow doors, bulkhead valve, stern thruster, etc.; special antenna technology giant with control devices, measurement buoys, movements such as rotating stage; military-industrial control devices used in artillery, ship anti- rolling devices, aircraft simulation, aircraft retractable landing gear and rudder control devices and other devices.The role of the hydraulic system to increase the force by changing the pressure. A hydraulic system is good or bad depends on the system design is reasonable, the merits of the performance system components, system, pollution prevention and treatment, while the last point is particularly important. In recent years, China's domestic hydraulic technology has greatly improved, not simply using hydraulic technology from abroad for processing.A complete hydraulic system consists of five parts, namely, power components, the implementation of components, control components, auxiliary components (Annex) and the hydraulic oil.The role of dynamic components is the original motivation of the mechanical energy into fluid pressure energy, the hydraulic system of pumps, which provide power to the entire hydraulic system. Structures of hydraulic pumps generally have gear pumps, vane pumps and piston pumps.Implementation of components (such as hydraulic cylinders and hydraulic motors) is to pressure the liquid can be converted to mechanical energy to drive the load for a linear reciprocating movement or rotational movement.Control components in the hydraulic system control and regulation of fluid pressure, flow and direction. According to the different control functions, hydraulic valves can be divided into pressure control valves, flow control valves and directional control valve. Pressure control valve is divided into benefits flow valve (safety valve), pressure relief valve, sequence valve, pressure switch, etc.; flow control valves including throttle, adjusting valves, flow diversion valve assembly; Directional control valve includes a check valve, check valve, shuttle valve, valve and so on. Under the control of different ways, hydraulic valves can be divided into switching control valves, control valves and the fixed value proportional control valve.Auxiliary components, including fuel tanks, filters, tubing and pipe joints, seals, quick couplings, high pressure ball valve, hose assembly, pressure fittings, pressure gauge, oil level, oil temperature meter and so on.Hydraulic system of hydraulic oil is the work of the energy transfer medium, a variety of mineral oil, emulsion, oil hydraulic molding Hop categoriesThe role of the hydraulic system is to help humanity work. Mainly by the implementation of components to rotate or pressure into a reciprocating motion.Hydraulic principle ：It consists of two cylinders of different sizes and composition of fluid in the fluid full of water or oil. Water is called "hydraulic press"; the said oil filled "hydraulic machine." Each of the two liquid a sliding piston, if the increase in the small piston on the pressure of a certain value, according to Pascal's law, small piston to the pressure of the pressure through the liquid passed to the large piston, piston top will go a long way to go. Based cross-sectional area of the small piston is S1, plus a small piston in the downward pressure on the F1. Thus, a small piston on the liquid pressure to P = F1/SI, Can be the same size in all directions to the transmission of liquid. "By the large piston is also equivalent to the inevitable pressure P. If the large piston is the cross-sectional area S2, the pressure P on the piston in the upward pressure generated F2 = PxS2 Cross-sectional area is a small multiple of the piston cross-sectional area. From the type known to add in a small piston of a smaller force,the piston will be in great force, for which the hydraulic machine used to suppress plywood, oil, extract heavy objects, such as forging steel.The secret of hydraulic systems success and widespread use is its versatility and manageability．Fluid power is not hindered by the geometry operations when the potential difference between the tool and the work piece is sufficiently high, a transient spark discharges through the fluid, removing a very small amount of metal from the work piece of the machine as is the ease in mechanical systems．Also，power can be transmitted in almost limitless quantities because fluid systems are not so limited by the physical 1imitations of materials as are the electrical systems．For example，the performance of an electromagnet is limited by The saturation limit of steel．On the other hand，the power limit of fluid systems is 1imited only by the strength capacity of the material．Industry is going to depend more and more on automation in order to increase productivity．This includes remote and direct control of production operations，manufacturing processes。