AMESim液压培训(PPT68页)

合集下载

液压基础知识培训资料幻灯片PPT

先导操纵阀
先导操纵阀
工作原理：手柄输出位移，使顶杆压缩弹簧并带动阀芯下移，控制油减压输出。输出压力与弹簧3的压缩量〔弹簧力〕成比例，输出压力与弹簧 3通过阀芯构成平衡状态。当输出压力大于弹簧3的作用力时，阀芯上移，控制油窗口减小，输出压力减小，直到输出压力与手柄的操作要求相适应。在最大手柄位移时，控制油等压输出。
泄漏油路——一些元件如泵、马达、控制阀等泄漏的流量需直接回油箱，要求一般无压力或压力很小＜1bar.具有无压，小
流量的特点。
控制油路——为控制主油路元件而提供液压动力源的油路。通常包括控制泵，过滤器，蓄能器，溢流阀，换向阀，先导操
纵阀等元件。
操作类型：直动式操作，间接式操作
先导操纵阀
本节所述的先导操纵阀限于先导液控系统的元件。根据操作部位、油路通道数量的不同，先导液控操纵阀可以有手柄式，脚踏式，单手柄，多联手柄等不同的构造构造形式。
起重机的工作原理
起重机的平安保护起重机的平安保护有：超载保护，如力矩限制器。其作用是当起重机处于超载范围时截断危险方向的运动。这种截断根据液压系统类型的不同而不同。当系统为先导液压控制时，是截断控制油路〔通过截断相应电磁阀的电路，使控制油路卸荷〕进而截断主油路；当系统为直动型控制时，是截断主工作油路；〔通过截断相应电磁溢流阀的电路〔或遥控式溢流阀的泄荷电磁阀的电路使控制油路卸荷〕进而使主工作油路卸荷这种保护方式是在任何压力值上均可进展的，因此要求压力释放要彻底。另一种平安保护方式是限位保护。如高度〔过卷〕限位，三圈〔过放〕保护。这种保护方式亦是在任何压力值上均可进展的，也要求压力释放要彻底。综上所述，起重机的平安保护是通过截断液压油路的压力、流量方式进展的。涉及的机构有主、副起升机构〔起升和下降方向〕、变幅机构〔向下变幅方向〕、伸缩臂机构〔伸出方向〕。

Amesim 液压仿真学习

Hydraulic LibraryRev 9 - November 2009Copyright © LMS IMAGINE S.A. 1995-2009AMESim® is the registered trademark of LMS IMAGINE S.A.AMESet® is the registered trademark of LMS IMAGINE S.A.AMERun® is the registered trademark of LMS IMAGINE S.A.AMECustom® is the registered trademark of LMS IMAGINE S.A.LMS b is a registered trademark of LMS International N.V.LMS b Motion is a registered trademark of LMS International N.V.ADAMS® is a registered United States trademark of MSC.Software Corporation. MATLAB and SIMULINK are registered trademarks of the Math Works, Inc. Modelica is a registered trademark of the Modelica Association.UNIX is a registered trademark in the United States and other countries exclusively licensed by X / Open Company Ltd.Python is a registered trademark of the Python Software Foundation.Windows and Visual C++ are registered trademarks of the Microsoft Corporation. The GNU Compiler Collection (GCC) is a product of the Free Software Foundation. See the GNU General Public License terms and conditions for copying, distribution and modification in the license file.All other product names are trademarks or registered trademarks of their respective companies.Hydraulic Library Rev 9 Table of contentsChapter 1:Tutorial examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11.1Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2Example 1: A simple hydraulic system . . . . . . . . . . . . . . . . . . . . . . 2Cavitation and air release. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91.3Example 2: Using more complex hydraulic properties . . . . . . . . . 11Using one of the special fluids . . . . . . . . . . . . . . . . . . . . . . . . . . 121.4Example 3: Using more complex line submodels . . . . . . . . . . . . . 171.5Example 4: Valves with duty cycles. . . . . . . . . . . . . . . . . . . . . . . . 221.6Example 5: Position control for a hydraulic actuator. . . . . . . . . . . 271.7Example 6: Simple design exercise for a hydraulic suspension . . 33Chapter 2:Theory of fluid properties. . . . . . . . . . . . . . . . . . . . . .412.1Density and compressibility coefficient . . . . . . . . . . . . . . . . . . . . . 41Entrapped air . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42Dissolved air. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 432.2Air release and cavitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 442.3Viscosity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46Viscosity influence on the flow. . . . . . . . . . . . . . . . . . . . . . . . . . 48Flow through orifices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49Frictional drag. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53Chapter 3:AMESim Fluid Properties . . . . . . . . . . . . . . . . . . . . . .553.1Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55FP04. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 553.2Tutorial example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60Chapter 4:Hydraulic Line modeling. . . . . . . . . . . . . . . . . . . . . . .614.1Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61Zero-dimensional line submodels. . . . . . . . . . . . . . . . . . . . . . . . 61“Lumped” and “Lumped distributive” line submodels. . . . . . . . . 62Lax-Wendroff “CFD 1D3” line models . . . . . . . . . . . . . . . . . . . . 63Choosing between Lumped/Distributive and CFD 1D Lax-Wendroffmodels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 644.2Line submodel selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 641Table of contents24.3Three important quantities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65Aspect ratio. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65Dissipation number. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66Communication interval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .67 4.4The selection process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .68Hydraulic Library Rev 9 Chapter 1: Tutorial examples1.1IntroductionThe AMESim Hydraulic library consists of:• A collection of commonly used hydraulic components such as pumps, motors, orifices, etc. including special valves.•Submodels of pipes and hoses.•Sources of pressure and flow rate.•Sensors of pressure and flow rate.• A collection of fluid properties.Hydraulic systems in isolation serve no purpose. It is necessary to do somethingwith the fluid and also to control the process. This means that the library must becompatible with other AMESim libraries. The following libraries are frequently usedwith the Hydraulic library:Mechanical libraryUsed in fluid power application when hydraulic power is translated into mechanicalpower.Signal, Control and Observer libraryUsed to control the hydraulic system.Hydraulic component design libraryUsed to build specialist components from very basic hydraulic and mechanicalelements.Hydraulic resistance libraryThis is a collection of submodels of bends, tee-junctions, elbows etc. It is usedtypically in low pressure applications such as cooling and lubrication systems.1Chapter 1Tutorial examples2Chapter 1 of the manual consists of a collection of tutorial examples. We strongly recommend that you do these tutorial examples. They assume you have a basic level of experience using AMESim . As an absolute minimum you should have done the examples in Chapter 3 of the AMESim manual and the first example of Chapter 5 which describes how to do a batch run.1.2Example 1: A simple hydraulic systemObjectives•Construct a very simple hydraulic system •Introduce the simplest pipe/hose submodels •Interpret the results with a special reference to air release and cavitationFigure 1.1: A very simple hydraulic system In this exercise you will construct the system shown in Figure 1.1. This is perhaps the simplest possible meaningful hydraulic system. It is built partly fromcomponents from the Hydraulic category (which are normally blue) and partly from the Mechanical category.The hydraulic section is built up from standard symbols used for hydraulic systems. The prime mover supplies power to the pump, which draws hydraulic fluid from a tank. This fluid is supplied under pressure to a hydraulic motor, which drives a rotaryNote:•You can use more than one fluid in the Hydraulic library. This is important because you can model combined cooling and lubrication systems of a library.•The hydraulic library assumes a uniform temperature throughout the system. If thermal effects are considered to be important, you should use the Thermal Hydraulic and Thermal Hydraulic Component Design libraries.•There are models of cavitation and air release in the hydrauliclibrary. Note also there is a special two-phase flow library. Atypical application for this is air conditioning systems.Hydraulic Library Rev 9load. A relief valve opens when the pressure reaches a certain value. The output from the motor and the relief valve returns to the tank. The diagram shows three tanks but it is quite likely that a single tank is employed.The first category contains general hydraulic components. The second contains special valves.The hydraulic components used in the model you will build can all be found in the first of these Hydraulic categories. If you click on this category icon, the dialog box shown in Figure 1.2 opens.First look at the components available in this library. Display the title of components by moving the pointer over the icons:Figure 1.2: The components in the first hydraulic category.Close the Library before continuing.3Chapter 1Tutorial examples4Step 1:Use File X New... to produce the following dialog box.Figure 1.3: The hydraulic starter system.Step 2:Construct the rest of the system and assignsubmodels1.Construct the systemwith the components as shown in Figure 1.1.2.Save it ashydraulic1.3.Go to Submodel mode.Notice that the drop, prime mover, node and pipes do not appear the same as they usually do. This is because they do not have sub models associated with them.The easiest way to proceed is as follows:4.Click on the Premier submodel button in the menu bar.Select the hydraulic starter circuit libhydr.amt and then click onOK. A new system with a fluid properties icon in the top leftcorner of the sketch is created.You could also have clicked on the New icon in the tool bar butif you do this you will have to add the fluid properties iconyourself.Hydraulic Library Rev 95Figure 1.4: The line submodels.You get something like Figure 1.4. It is possible that your system may have HL000associated with one of the other line runs. These minor variations are dependent on the order in which you constructed the lines. They will not influence the simulation results.An important feature to note is that a line run has a special submodel (HL000) which is not a direct connection. To emphasize this point the line run has a special appearance:Remember the submodel DIRECT does nothing at all. It is as if the ports at each end of the line were connected directly together.In contrast, HL000 computes the net flow into the pipe and uses this to determine the time derivative of pressure. If the net flow into the pipe is positive, pressure increases with time. If it is negative, it decreases with time. The pressure created by HL000 is conveyed to the relief valve inlet. The motor inlet is conveyed by the node and submodel DIRECT .5.Click the mouse right-button.6.Select Show line labels in the label menu.Chapter 1Tutorial examples6Step 3:Set parameters1.Change to Parameter mode.2.Set the following parameters and leave the others at their default values:Figure 1.5: Setting the line submodel HL000 parameters.3.To display the parameters of a line submodel click the left mouse button with thepointer on the appropriate line run.Part of the dialog box for HL000 is shown in Figure 1.5. The compressibility of the oil and the expansion of the pipe or hose with pressure are taken into ac-count together with the pipe volume. HL000 normally requires the bulk modulus of the hydraulic fluid and pipe wall thickness together with the Young’s modulus of the wall material. From these values an effective bulk modulus of the com-bined fluid and pipe walls can be calculated. The effective bulk modulus of a hose is normally very much less than that of a rigid steel pipe.4.Click on the fluid icon FP04 in the sketch.A new dialog box as shown in Figure 1.6 is displayed. This shows you the prop-erties of the hydraulic fluid. Currently they are at their default values and the ab-solute viscosity, bulk modulus, air/gas content and temperature are given in common units.Submodel Title ValueHL000pipe length [m]4RL00coefficient of viscous friction [Nm/(rev/min)]0.02Figure 1.6: Parameter for fluid properties submodel FP04.5.Click on Close .Step 4:Run a simulation1.Go toSimulation mode and do a simulation run.The default values in the Run Parametersdialog box are suitable for this exam-ple.2.Click on the Start a simulation button.3.Click on the pump component to produce the dialog box shown in Figure 1.7.Some variables such as a pressure have no direction associated with them. ANote that the first item in the list is an enumeration integerparameter. A collection of properties of varying complexityare available but for this exercise elementary is satisfacto-ry.Tutorial examples(gauge) pressure of -0.1 bar indicates that the pressure is below atmospheric.In contrast other variables, such as flow rate, do have a direction associatedwith them. A flow rate of -6 L/min indicates that the flow is in the opposite direc-tion to some agreed standard direction.Figure 1.7: The Variable List for PU001.Note that you can use the Replay facility to give you a global picture of the re-sults. Figure 1.8 also shows the flow rates in L/min at a time of 10 seconds.Figure 1.8: Flow rates displayed in replay.4.To plot a variable associated with a line submodel, click on the correspondingline run.5.Plot pressure at port 1 for HL000.Figure 1.9: The pressure in the hydraulic pipe.Notice how the pressure goes up to just over the relief valve setting (150 bar).During this time the load speeds up rapidly and actually 'over-speeds'. At thispoint the motor is demanding more hydraulic flow than the pump can supply.The result is that the pressure must drop and the relief valve closes. The pres-sure continues to drop and falls below zero bar gauge. However, pressure is notlike voltage or force. We cannot have a pressure of -100 bar. The absolute zeroof pressure is about -1.013 bar gauge. It is time to introduce two terms. Cavitation and air releaseWhen pressure falls to very low levels, two things can happen:•Air previously dissolved in the fluid begins to form air bubbles.•The pressure reaches the saturated vapor pressure of the liquid andbubbles of vapor appear.These phenomena are known respectively as air release and cavitation. They cancause serious damage. Using the Zoom facility, the graph gives a better view of thelower pressure values:Figure 1.10: Low pressure in the hydraulic pipeAll AMESim submodels have hydraulic pressure in bar gauge. The low pressureshown in Figure 1.10 : Low pressure in the hydraulic pipe is caused by the loadTutorial examplesspeed exceeding its steady state or equilibrium value. This is highly undesirablebehavior as it can result in damage to the real system.In reality the starting values we have given for the pipe pressure and load speed arenot very realistic and the prime mover would start from rest or a valve would be usedto regulate the flow to the motor. However, hydrostatic transmission systems likethis often do suffer badly from cavitation and air release problems.Note that all AMESim submodels display hydraulic volumetric flow rate in L/min.There are two possible interpretations of this flow rate:•The flow rate is measured at the local current hydraulic pressure, or•The flow rate is measured at a reference pressure.AMESim adopts the second alternative with a reference pressure of 0 bar gauge.This means that the volumetric flow rate is always directly proportional to the massflow rate. In most situations the difference between the two flow rates is negligible.However, there are three situations when there is a significant difference:1.There is a very large air content; the pressure drops below the satu-ration pressure for air in the liquid and air bubbles are formed in theliquid.2.The pressure drops to the level of the saturated vapor pressure of theliquid and cavities of vapor form.3.Extremely high variations in pressure occur such as in certain typesof fuel injection systems.The first situation is called air release and the second cavitation. If there is cavitationor significant air release at the inlet to a pump, the flow rate according to the firstdefinition will not be reduced. However, with the AMESim approach (measuringflow rate at a reference pressure) it is significantly reduced.The properties of hydraulic fluids vary a great deal. Modeling them is a veryspecialist process and the model can be extremely simple or highly complex. Therun times are greatly influenced by this level of complexity.1.3Example 2: Using more complex hydraulicpropertiesObjectives:•Use more complex models of fluid properties.•See how air content changes the performance of the system.In the Hydraulic category two special components can modify the fluid properties:This is an example of a component without ports. We cannot connect this icon to any other.There are two important points to note aboutFP04.1.It has an integer parameter index of hydraulic fluid that is in the range 0 to 100inclusive. This arrangement means that it is possible to have more than one fluidin an AMESim system.•simplest This has a constant absolute viscosity. The bulk modulus isconstant above the gas saturation pressure and is 1/1000 of this valuebelow the gas saturation pressure. This model is very old but is still usedby some AMESim users.It is likely to give the fastest runs.•elementary This is the default and features a constant liquid bulk mod-ulus with absolute viscosity. The treatment of fluid properties under airrelease and cavitation is done.•advanced This gives you access to some cavitation parameters not ac-General Hydraulic PropertiesIn AMESim always use this fluid properties icon. It is associated withone submodel: FP04. This is a collection of simple and complex fluidproperties.Drop Hydraulic PropertiesThis is a special model, only used to ensure backward compatibilitybetween 4.0 models and earlier. Do not use this model.2.The characteristics of the fluid properties are de-termined by its parameters. These are set in thetype of fluid properties list. There are 7 possi-bilities:Tutorial examplescessible in the elementary properties.•advanced using tables This is like the advanced option but you install tables of data to give variation of bulk modulus and absolute viscositywith pressure and temperature.•Robert Bosch adiabatic diesel These properties are provided by Rob-ert Bosch GmbH and comprise a number of common types of diesel fuel.•elementary with calculated viscosity•advanced with calculated viscosityUsing one of the special fluidsStep 1:Use the Advanced fluid properties.1.Return to the first example of this manual, add another fluid properties icon.e Premier submodel and go to Parameter mode. Your sketch should look likethis.Figure 1.11: The sketch with two instances of FP04.3.Look at parameters of FP04-2. Change the enumeration integer parameter toadvanced. The Change Parameters list should now look like this:Figure 1.12: The advanced fluid properties.Change the index of hydraulic fluid in FP04-2 to 1. This is a number in the range0 to 100. If you look at the other hydraulic components in the system you willfind they have index 0 and hence they will still use the fluid properties of FP04-1. We could go into every hydraulic component using this second fluid and setthe parameter index of hydraulic fluid to 1. This would be extremely tedious witha big system and there is always the possibility of missing one.Instead we can set all fluid indices to the same value of 1.Step 2:Set all fluid indices to the same value of 1The best way to do this is to use the common parameters facility.e Edit X Select all.All the system components will be selected, unselect FP04-1 by holding the SHIFT key and clicking on the component.Figure 1.13 Select componentse Settings X Common parameters.Tutorial examplesFigure 1.14 shows the Common parameters dialog box. This is a list of commonparameters for selected objects. They occur at least twice. Since there are 3 hy-draulic tanks and they all have pressures of 0 bar, this value is displayed. Thereare a number of submodels that have a parameter index of hydraulic fluid. InFP02 the index of hydraulic fluid is set to 1 whereas in other submodels its valueis 0. The value is displayed as ???. Similarly the prime mover and rotary loadboth have a parameter (strictly speaking a variable) with title shaft speed. Sincethe two values are different, ??? is displayed.Figure 1.14: Different values for common parameters3.Set the parameter index of hydraulic fluid to 1. This will change all the parame-ters in the system except FP01 (remember we used Select all and deselectedFP01).Step 3:Run a simulation and plot some variablesYou will probably find the results very much the same as in example 1.Step 4:Organize a batch run to vary the air content1.In Parameter mode use Settings X Batch parameters.2.Drag and drop the air gas content from FP04-2 to the Batch control parametersetup dialog box.3.Set up the batch parameters as in Figure 1.15 so that the air content goes from0% to 10% in steps of 2%.Figure 1.15: Setting up a batch run varying air content4.Specify a batch run in the Run parameters dialog box and initiate the run.5.Plot several graphs of the batch run to compare results with various air contents:Tools X Batch Plot .Figure 1.16: Pressure in pipe.By zooming in on the curve in regions where the pressure is below 0 bar, you will probably find some variation in the results, but not to a significant degree.6.Change the saturation pressure in FP04-2 to 400 bar.7.Repeat the batch run and update your plot.Tutorial examplesFigure 1.17: Pressure in pipe with saturation pressure 400 bar.The variation between the runs is now very pronounced. The dynamiccharacteristics of the system are completely transformed. A few words ofexplanation are necessary.Normally the air content of a hydraulic oil is well below 1%. A typical value is 0.1%.It is normally considered good practice to keep the value as low as reasonablypossible. However, in a few applications, such as lubrication oil in gearboxes, theoil and air are well mixed. In this case, 2.5% is a typical value, and up to about 10%is possible.A reasonable quantity of air, given time, will completely or partially dissolve in thehydraulic fluid. The lowest pressure at which all the air is dissolved is called thesaturation pressure. For very slow systems all the air is dissolved above thesaturation pressure and partially dissolved below this pressure. Henry’s law givesa reasonable approximation for the fraction of air that is dissolved in equilibrium.Some systems are slow enough to stay very close to this equilibrium position(Figure 1.16). Often classic fluid power systems behave like this. The originalsaturation pressure is better for the current example.However, it does take time for the air to dissolve and this time will not be availablein fast acting systems. Fuel injection systems are a good example of this. Hencewith such systems it may be appropriate to set the saturation pressure artificiallyhigh to allow for significant quantities of air to be undissolved at all pressures.1.4Example 3: Using more complex line sub-modelsObjectives:•Use more complex line submodels.•Understand the need for a variety of line submodels.•To understand the importance of setting an appropriate line submodel.The system for this example is the same as for example 2 (Figure 1.11). We will describe the modification of the system to use more complex line submodels and the experiments performed. Finally we present a little of the theory behind the submodels.Step 1:Change submodelsAll the submodels in the current system were selected automatically. We willchange some of them manually.1.Go to Submodel mode.You will now change some line submodels.Before continuing note the following points:•The corners in the pipe runs are not physical but diagrammatic.•There are three hydraulic pipes and they meet at a point which physically will be a tee-junction.•It is necessary to have a large number of hydraulic pipe submodels.•In the present system three submodels are set: DIRECT , DIRECT andHL000.Figure 1.18: The current line submodels.None of these line submodels takes friction into account. We will suppose that the relief valve is close to the node but the pump and the motor are at such distances•This tee-junction in the sketch is described as a 3-portnode and it has the submodel H3NODE1. This modelsthe junction has a common pressure with flow rates thatgive conservation of mass.Tutorial examplesfrom the node that the pressure drop along the pipes cannot be ignored. We need to select new pipe submodels that take friction into account for the pipe runs:•from the pump to the node •from the node to the motor.2.Click on the line run attached to the pump and select HL03 in the Submodel list .Figure 1.19: The hydraulic line submodels available.Why did we not choose a more complex submodel that also included inertia? We answer this question later in this exercise.3.For the line from the node to the motor, select the submodel HL01.4.For the line between the node and the relief valve, the submodel DIRECT is al-ready selected and this is exactly what we want.Step 2:Set parameters and run a simulation1.Go to Parameter mode and set parameters for HL01 and HL03 so that both pipelengths are 5 m and pipe diameters are 10 mm .This can be done one at a time. However, we can do it another way. Press the Shift key on click on the HL03 and HL01 line runs so that they are selected. Use Settings X Common parameters . Figure 1.20 shows the Commonparameters dialog box.Note the brief description of each line submodel. In these de-scriptions C stands for compressibility, R for resistance (pipefriction) and I for inertia (fluid momentum). HL000 which weused before takes into account compressibility only. HL03takes into account compressibility and friction. It is modeled liketwo hydraulic compressible volumes with a resistance betweenthem.Figure 1.20: The common parameters of the two line submodels.Note that ??? indicates that different values are set in the line submodels. Set the index of hydraulic fluid to 1, diameter of pipe to 10 and pipe length to 5.2.In FP04-2 reset the saturation pressure (for dissolved air/gas) to 0 bar.3.Run a simulation with the default run parameters. Do not forget to reset RunType to Single run if you have previously run a Batch.4.Plot the two pressures in HL03.Figure 1.21: Pressures at the ends of pipe joining pump to node.Note that there is a large pressure drop along the line. This could be regarded as a sizing problem but in addition it would be bad practice to site the relief valve so far from the high pressure point.Tutorial examplesStep 3:We now investigate other line submodels.1.Return to Sketch mode and Copy-Paste part of the system as shown:Figure 1.22: Part of the system is duplicated.2.In Submodel mode change the lower two line submodels as follows:Figure 1.23: New line submodels.This system will enable you to make direct comparisons between results.3.Go to Run mode and do a simulation. Plot the pressure at the pump outlet (pres-sure at port 2).Figure 1.24: Pressure at pump outlet.We note that the curves are virtually the same. (Try zooming.) There is abso-lutely no advantage to using HL07 and HL09 instead of HL01 and HL03. If we separated the two systems and ran them independently we would find run times for the more complex submodels were higher.4.C hange the communication interval in the Run Parameters dialog box to 0.001sand rerun the simulation.If you have a look at the Warnings/Errors tab of the Simulation run dialog box, you will find that some checks are performed by the line submodels (see Figure1.25). A similar message is issued for HL03.Figure 1.25: Messages under the Warning tab.It is suggested that:•HL01 should be replaced by HL07 and•HL03 should be replaced by HL09.In other words with this communication interval the lower subsystem is better than the upper. If you replot the pressures at the pump outlets, there are clearly differences. This is what happens if you zoom.Figure 1.26: Zoomed pressures at pump outlet.The violent (and unrealistic) start up has created this oscillation in the pressure of about 56 Hz. It is damped out by 0.1 seconds. Why did we get no warning message in the previous run? The answer is that a lot of checks are applied to your submodel choices when the run starts. These take into account the fluid properties, the pipe dimensions and the communication interval.。

amesim培训课件

amesim培训课件AMESim培训课件AMESim是一种功能强大的多领域仿真软件，广泛应用于汽车、航空航天、能源等领域。

它能够帮助工程师们在产品开发的早期阶段进行系统级建模和仿真，以便更好地理解和优化系统的性能。

为了更好地掌握AMESim的使用技巧和应用方法，许多企业和工程师都会参加AMESim培训课程。

在AMESim培训课程中，学员们将会学习如何使用AMESim进行系统级建模和仿真。

课程的内容包括软件的基本操作、模型建立和参数设置等方面。

通过理论讲解和实际操作相结合的方式，学员们可以更好地理解AMESim的原理和应用方法。

在课程的开始阶段，学员们将会学习AMESim的基本操作。

这包括软件的安装和配置、界面的介绍以及常用工具的使用等方面。

通过这些基础知识的学习，学员们可以快速上手使用AMESim进行建模和仿真。

接下来，学员们将会学习如何建立系统级模型。

AMESim支持多领域的建模，包括液压系统、热力系统、电力系统等。

学员们可以根据自己的需求选择相应的模块进行建模。

课程中将会介绍不同模块的功能和使用方法，帮助学员们更好地理解和掌握建模技巧。

除了模型建立，参数设置也是AMESim培训课程的重要内容之一。

学员们将会学习如何设置模型的参数，包括物理参数、控制参数等。

通过调整参数的方式，学员们可以对系统进行优化和改进。

课程中将会介绍不同参数的意义和调整方法，帮助学员们更好地理解和应用。

在AMESim培训课程的最后阶段，学员们将会进行实际案例的仿真。

这些案例涵盖了不同领域的应用，包括汽车动力系统、航空发动机等。

通过实际案例的仿真，学员们可以将所学知识应用到实际工程中，提升自己的实践能力。

除了课堂学习，AMESim培训课程还提供了在线学习资源。

学员们可以通过在线平台获取相关的学习资料和视频教程。

这些资源可以帮助学员们巩固所学知识，提高学习效果。

总的来说，AMESim培训课程是一种提高工程师仿真技能的有效途径。

液压知识培训课件

液压知识培训课件
液压知识培训课件
液压技术是一种利用液体传递能量和控制信号的技术。

它在工程领域中广泛应用，包括机械制造、航空航天、农业机械、建筑工程等。

为了更好地掌握液压
技术，我们需要进行液压知识的培训。

液压知识培训课件是一种有效的学习工具，它通过图文并茂的方式，结合实例
和案例分析，系统地介绍了液压技术的基本原理、工作原理、组成部分、常见
故障及排除方法等内容。

通过学习这些课件，我们可以更好地理解液压技术的
运作原理，提高自己的液压技术水平。

液压知识培训课件的内容丰富多样。

首先，它介绍了液压技术的基本原理，包
括液压力传递、液压能量转换、液压控制等。

通过学习这些原理，我们可以了
解液压技术的基本概念和运作方式。

其次，液压知识培训课件还介绍了液压系统的组成部分，包括液压泵、液压阀、液压缸等。

通过学习这些组成部分的结构和功能，我们可以了解液压系统的工
作原理和各个部件之间的关系。

此外，液压知识培训课件还包括了常见的液压故障及排除方法。

在实际应用中，液压系统可能会出现各种故障，如泄漏、阀门卡死、液压缸无法正常工作等。

通过学习这些故障及排除方法，我们可以更好地解决液压系统的故障问题，提
高工作效率。

总之，液压知识培训课件是一种重要的学习工具，它可以帮助我们更好地掌握
液压技术。

通过学习液压知识，我们可以在实际工作中更加熟练地运用液压技术，提高工作效率，为工程领域的发展做出更大的贡献。

因此，我们应该积极
参与液压知识的培训，不断提升自己的技术水平。

液压培训ppt课件

液压系统对液压缸的位置控制精度要求较高，采用了死挡铁停留来保证其定位精度及加工的重复性。
万能外圆磨床液压系统
磨床工作台的往复运动采用了由换向阀换向的液压缸回路。
砂轮箱横向进给运动采用了由换向阀换向的液压马达回路。为减小换向冲击，采用电液换向阀换
向。
磨床液压系统的特点：执行元件多、要求同步运动、调速范围大
且平稳、保压性能要求高。
05
液压系统的设计与计算
明确设计要求进行工况分析
明确设计要求
了解设备的用途、性能、工作环境等，确定液压系统的设计要求。
进行工况分析
分析设备的工作循环、负载特性、速度特性等，为液压系统设计提供依据。
确定系统类型
根据工况分析结果，选择合适的液压系统类型，如开式系统、闭式系统等。
液压系统的使用维护
使用操作规范
01
遵守操作规程，避免违规操作；保持系统清洁，定期更换液压
油和滤芯。
日常维护内容
02
定期检查系统压力、温度、流量等参数是否正常；检查管道、
接头等是否泄漏；检查紧固件是否松动。
定期保养计划
03
根据设备使用情况，制定定期保养计划，包括更换液压油、清
洗油箱、检查电气元件等。
THANKS
感谢观看
压缩性
油液受压力作用时体积缩小的性质，影响系统的动态响应和稳定性。
润滑性
油液具有润滑摩擦副的作用，减少磨损和摩擦
热。
液压系统组成
执行元件
将液体的压力能转换为机械能，驱动工作机构运动，如液压缸和液压马达。
辅助元件
包括油箱、滤油器、冷却器、加热器、蓄能器等，保证系统正常工作。

液压基础知识培训PPT课件

液压传动系统的组成及图形符号
下图所示为一简化的机床工作台液压传动系统：油箱、过滤器、液压泵、溢流阀、节流阀、换向阀、液压缸、工作台。
工作原理
▲液压泵由电动机带动旋转，在入口处产生负压，在大气压的作用下油液经过滤器2过滤后流往液压泵3；
▲经泵输往系统的油液有一定压力，经节流阀56进入液压缸7的左腔，推动活塞连同工作台8向右运动。
8
节流阀、方向阀等。用来控制液压系统
中油液的压力、流量、流动方向等。
7
▲辅助元件——油箱、油管、过滤器、指示器、控制仪表等。作用是提供必要的条件使得系统正常工作和便于监测系统。 ▲工作介质——液压油、水等。通过工作介质实现运动和动力的传递。
潘存云教授研制
6
5 4
3
1
2
2
★动力元件：液压泵
（一）.液压泵的工作原理：液压系统常用的液压泵有齿轮泵，叶片泵和柱塞泵三大类，其工作原理都是依靠液压泵密封工作容积大小交替变化来实现吸油和压油的，所以称为容积式泵。
（二）.液压泵的主要性能参数 1.液压泵的压力：工作压力，额定压力 2.液压泵的排量与流量： 3.液压泵的功率与效率：
泵 3
齿轮泵
一、外啮合齿轮泵的工作原理：
4
二、内啮合齿轮泵的工作原理：
吸油窗口
从动内齿轮
月牙板
内啮合齿轮泵中的小齿轮是主动轮，大齿轮为从动轮，在工作时大齿轮随小齿轮同向旋转。
⑴ 用作背压阀:
⑵ 对液压缸进行锁紧:
22
二、换向阀:
⒈ 滑阀式换向阀的工作原理:
滑阀式换向阀通过变换阀芯在阀体内的相对工作位置, 使阀体内各油口连通或断开, 从而控制执行元件的运动、停止和换向。

液压培训PPT课件

液压系统的组成
总结词
列举液压系统的基本组成部分
详细描述
液压系统通常由以下部分组成
动力元件
包括液压泵，用于提供液压系统所需的压力能。
执行元件
如液压缸和液压马达，用于将液体的压力能转换为机械能。
控制元件
如各种阀门和溢流阀，用于控制液体的流量、压力和方向。
辅助元件
包括油箱、滤油器、冷却器和管道等，用于保证液压系统的正常运转。
定期更换液压油可以防止油品老化、变质，保证液压系统的性能。
在更换液压油时，需要检测液压油的油质、油位、油温等参数，
确保油品正常。
液压元件的清洁与保养
液压元件的清洁度对液压系统的性能有很大影响。
对液压元件进行保养，如涂抹润滑脂、紧固螺丝等，可以延长元件的使用寿命。
定期清洗液压元件，清除杂质和污垢，可以保证液压元件的正常运行。
压力异常
压力异常可能导致执行元件无法正常工作或系统效率降低。排除方法包括检查溢流阀、减压阀等控制阀是否正常工作。
泄漏
泄漏不仅浪费液压油，还可能引起环境污染和安全问题。排除方法包括更换密封件、拧紧连接处和检查管路是否破损等。
04 液压系统的维护与保养
液压油的更换与检测
液压油是液压系统的血液，对液压系统的正常运行至关重要。
液压系统的定期检查与调试
定期对液压系统进行检查，可以及时发现潜在的问题和故障。
对液压系统进行调试，可以保证其性能和精度，提高系统的稳定性和可靠性。
在检查和调试过程中，需要注意安全问题，遵循操作规程，确保人员安全。
05 液压系统的未来发展与趋势
液压技术的发展方向
高效节能
随着环保意识的提高，液压系统将更加注重高效节能技术的研发和应用，以降低能源消耗和减少

液压基础知识培训（PPT）

液压基础知识培训（PPT）
领取方式在文章末尾。

本ppt包括的内容有液压原理、流体力学的基础知识、各种液压元件的原理、气动相关知识等。

下为本PPT的摘要，详情请看原PPT 的内容。

1、液压原理部分：
以典型的液压千斤顶为例，讲述液压传动的基本原理，液压能的传递。

液压基本原理：帕斯卡原理。

除此以外，还包括液压传动的流体力学基础，包括静力学方程、连续性方程、伯努利方程等。

2、液压元件
对常见的液压元件的工作原理和种类进行介绍。

动力元件：为液压系统提供液压能，包括齿轮泵、叶片泵、柱塞泵。

控制元件：包括压力控制阀、流量控制阀、方向控制阀。

执行元件：直接驱动负载做功。

3、气压传动的工作原理
领取方式：。

AMESim液压培训资料

Orifices 阻尼孔
损失的压力可以认为是液体速度U, 液体密度以及摩擦因子ξ (同元件的
几何形状有关)的函数
Plosses
1 Q2 1 2 U 2 A 2 2
(3)
当我们需要考虑液压管网的压力损失和流量分布时(HR library)，我们
主要用方程（3）
对于流量控制，需要用到一个关于流量系数Cq的方程，这个方程在
AMESim (HYD, HCD…)中经常用到。
Q Cq Ar
2

Pup Pdown where
1 2 Cq
(4)
14
）起主要作用还是粘性（ viscous ）起主导作用，存在两种流动状态（flow regime）：层流（ Laminar ）：流动非常平稳紊流（ Turbulent）：流体的运动不规则，在下游存在紊乱以及涡流等。
pressure term
(1)

total pressure
dynamic pressure
方程假设没有能量损失: 能量全部回收：如果A1 = A3 和h1 = h3 , P1 = P3
12
Orifices 阻尼孔
实际上是存在能量损失的，所以: P3 < P1 局部压力扰动压力损失
三个液压库每个库有不同方面功能各不相同但能够相互兼容，且以标准液压库(HYD )为基础
3
二、液压油属性相关设置 Fluid properties
液体属性
影响液体动态特性的三个基本属性: 密度 [kg/m3] 质量特性与流体的温度和压力有关

体积模量 [bar] 可压缩性 = 刚度特性粘度 [Pa.s] 阻尼特性

液压基础培训讲解 ppt课件

结论：作用在滑阀阀芯上的稳态液动力总是力图使阀口关闭。
32
液压传动之－流体动力学（选修）
管路中液体的压力损失
∵ 实际液体具有粘性 ∴ 流动中必有阻力，为克服阻力，须消耗能量，造成能量损失(即压力损失）
分类：沿程压力损失、局部压力损失层流：液体的流动是分层的，层与层之
间互不干扰。紊流（紊流（湍流）：液体流动不分层，
做混杂紊乱流动。
33
液压传动之－流体动力学（选修）
管路中的压力损失
❖ 沿程压力损失（粘性损失）：液体沿等径直管流动时，由于液体的粘性摩擦和质点的相互扰动作用，而产生的压力损失。
❖ 沿程压力损失原因内摩擦—因粘性，液体分子间摩擦外摩擦—液体与管壁间
❖ 局部压力损失：液体流经管道的弯头、接头、突变截面以及阀口滤网等局部装置时，液流会产生旋涡，并发生强烈的紊动现象，由此而产生的损失称为局部损失。
即 ∑F = d（mv）/dt 考虑动量修正问题，则有： ∴ ∑F =ρq(β2v2-β1v1) 层流 β=1.33 紊流 β= 1
31
液压传动之－流体动力学（选修）
动量方程
X向动量方程： ∑Fx = ρq (β2v 2x-β1v1x)
X向稳态液动力： F'x= -∑Fx = ρq (β1v1x-β2v2x)
❖ 工作介质— 液压油或压缩空气，作为传递运动和动力的载体。
15
液压传动之
液压传动的优点
❖ 力大无穷—单位质量输出功率大，容易获得大的力和力矩。一个小小的千斤顶可以顶起一俩载重汽车；
❖ 操纵控制方便，易于实现无级调速而且调速范围大,可以达100：1至2000：1；
❖ 可以简便地与电控部分组成电液一体的传动、控制，实现自动控制。

《液压基础知识培训》课件

2
航空航天
液压技术被广泛应用于飞机和航天器的起落架、刹车系统和操纵系统中。
3
工程机械
液压系统常用于挖掘机、装载机、起重机等工程机械中，驱动和控制各种工作装置。
气压压力效应
与液压压力效应类似，气压通过气体流动来传递压力。
液压容积效应
液体在压力变化时，容积会发生变化，这种现象称为液压容积效应。
液压系统维护和故障诊断
定期维护液压系统是确保其稳定性和可靠性的关键。故障诊断能够帮助我们快速识别并解决液压系统的问题。
液压系统的应用及案例分析
1
汽车制造业
液压系统在汽车生产线上起到重要作用，用于控制、定位和操纵各种机械装置。
《液压基础知识培训》 PPT课件
在本节中，我们将介绍液压系统的基础知识。包括液压系统的概述、基本液压元件、工作原理、组成和工作流程、液气压力和容积效应、系统维护和故障诊断、以及液压系统的应用和案例分析。
液压系统概述
液压系统是一种将液体用作传动力的工程技术，它利用液压流体传递能量和控制机械运动。
基本液压元件介绍
液压泵
液压系统的心脏，负责提供流为机械能，驱动工作装置运动。
液压阀
控制液压系统中的流体流动和压力。
液压系统的工作原理
液压系统工作基于Pascal原理，液体在封闭系统中传递压力，并将压力传递到工作装置实现机械运动。
液压系统的组成和工作流程
液体储备与供给
液压系统需要储备和提供足够的液体，以满足工作装置的需要。
工作装置的驱动
通过液压缸将液体能量转换为机械能，驱动工作装置完成任务。
压力传递与控制
液压泵提供压力，液压阀控制压力和流量，确保系统正常工作。

液压知识培训课件完整版

速下空载调试正常后，按液压系统的设计要求进行负载调试。首先逐渐增
加负载，同时检查各液压元件的工作状况，观察压力、流量、温度等参
数是否在允许范围内，发现问题及时进行调整。
03
系统试运行
负载调试正常后，进行系统试运行。试运行过程中，要密切注意系统的
运行状况，发现问题立即停机检查。
典型液压系统分析
动力滑台液压系统
该系统采用限压式变量叶片泵供油，通过电磁换向阀实现滑台的正反向运动，通过节流阀调节滑台的运动速度。
组合机床液压系统
该系统采用多个液压泵分别供油给多个执行元件，通过电磁换向阀和顺序阀等控制元件实现各执行元件的顺序动作和互锁功能。
塑料注射成型机液压系统
该系统采用定量叶片泵供油，通过比例压力阀和比例流量阀等控制元件实现对注射缸、合模缸等执行元件的精确控制。
制回路等。
考虑系统效率和性能，选择合适的元件规格和型号。
系统性能校核与优化
对设计好的系统进行性能校核，如压力损失、流量分配、温升等。
根据校核结果对系统进行优化，如调整元件参数、改进回路设计等。
确保系统在实际应用中能够满足设计要求。
设计图纸及文件编制
绘制液压系统原理图、装配图、零件图等必要图纸。
现对执行元件速度的控制。
快速运动回路
通过采用差动连接、双泵供油等方式，提高执行元件的运动速度。
速度换接回路
通过改变执行元件的通流面积或改变回路的流量分配等方式，实现执行元件在不同速度之间的平稳切换。
方向控制回路
换向回路
通过改变执行元件的通油方向，实现执行元件的正反向运动。
锁紧回路
通过采用液控单向阀等锁紧元件，使执行元件在停止运动后保持其位置不变。

AMESim液压培训解析

然而，空气含量(air/gas content),饱和压力(saturation pressure) 和蒸发压力( vapour pressures ),是处理气蚀现象（aeration/cavitation）必不可少的。
4
气穴 / 气蚀
掺混空气 - 气蚀
液体压力
溶解有空气的液体只有液体
11
Orifices 阻尼孔
U1 U2
U3
其中
Px = 静压 U = 流速 A = 过流面积
P1 A1
P2 A2
P3 A3
g = 重力加速度 h = 高度
ρ = 密度
1 1 2 2 P g h U P g h U 1 1 1 3 3 3 2 2 static gravity
这两种流动状态和雷诺数(Reynolds number)相关或者是流量系数λ。
Orifices 阻尼孔
损失的压力可以认为是液体速度U, 液体密度以及摩擦因子ξ (同元件的
几何形状有关)的函数
Plosses
1 Q2 1 2 U 2 A 2 2
(3)
当我们需要考虑液压管网的压力损失和流量分布时(HR library)，我们
三个液压库每个库有不同方面功能各不相同但能够相互兼容，且以标准液压库(HYD )为基础
3
二、液压油属性相关设置 Fluid properties
液体属性
影响液体动态特性的三个基本属性: 密度 [kg/m3] 质量特性与流体的温度和压力有关

体积模量 [bar] 可压缩性 = 刚度特性粘度 [Pa.s] 阻尼特性

《液压基础知识培训》ppt课件

对图纸和技术文件进行审查，确保准确无误。
06
液压系统安装调试与故障排除
安装前准备工作和注意事项
熟悉液压系统原理图、电气接线图、安装布置图等技术文件，了解系统动作原理、各元件的作用及安装位置。
准备合适的安装工具、测量仪表和清洁材料，确保安装过程中的清洁度。
检查液压泵、马达、阀等液压元件的型号、规格是否与图纸相符，确认各元件的完好性。
进行系统性能计算与校核
对液压系统进行性能计算，包括压力损失、流量分配、功率匹配
等；
对计算结果进行校核，确保系统性能满足设计要求；
如有需要，进行优化设计，提高系统性能。
绘制正式图纸和编写技术文件
根据设计结果，绘制正式的液压系统图纸，包括装配图、零件图等；
编写相应的技术文件，如设计说明书、使用维护手册等；
挖掘机液压系统
利用液压泵和液压马达驱动挖掘机的铲斗、动臂等部件，实现挖掘、装载等作业功能。
压路机液压系统
通过液压泵和液压马达驱动压路机的振动轮，实现路面的压实和平整。
05
液压系统设计方法与步骤
明确设计要求及参数
确定系统的工作压力、流量、温度等基本参数；
了解工作环境和使用条件，如振动、冲击、温度变化等。
明确执行元件的运动形式（直线或旋转）、运动速度、加速度等；
选择合适元件和回路
01
根据设计要求，选择合适的液压泵、液压马达、液压缸等动力元件；
02
选择适当的控制阀，如方向控制阀、压力控制阀、流量控制阀等；
03
根据需要选择合适的辅助元件，如油箱、滤油器、冷却器等；
04
确定合适的回路形式，如开式回路、闭式回路等。

AMESim液压教程

培训
流体特性 –混入空气（ Aeration）
24
¾ 空气释放（ Air release ）:
9 根据液压油所承受的压力不同，空气可以从掺混状态变化至溶解状态（反之亦然）。想象一下我们开启汽水瓶或者啤酒瓶看到的现象 …
9 饱和压力（ saturation pressure ）指的是一个临界压力，高于该压力不再有空气可以存在于液体中。
培训
15
¾液压流体特性
©IMAGINE SA 1998-2008
培训
液压流体特性
16
¾ 我们首先来了解流体特性在压力和流量计算中的作用。 ¾ 描述一种流体的特性和很多相关的术语：
密度（ Density ）
可压缩性（ Compressibility）
粘度（ Viscosity）
热胀冷缩性（ Thermal expansion）
9
¾ … 还有很多液压库中的元件会被经常使用到。尽管它们不是必不可少，但是它们的存在可以大大地提高建模的效率:
9 节点
9 节流和容积元件
9泵
9 管道 …
©IMAGINE SA 1998-2008
培训
AMESim液压方面库
蓄能器压力阀方向控制阀泵和马达液压缸
©IMAGINE SA 1998-2008
培训
液压系统的变量
14
¾ 两个主要相关的液压变量是：
9 压力 P 9 体积流量Q
¾ 对于机械液压元件(作动器、控制阀、压力调节阀…)，也需要一些机械变量:
9 速度 V, 位移 X, 加速度A 9 力 F以及扭矩T
¾ 我们在随后可以看到所交换变量的详细说明。 …
©IMAGINE SA 1998-2008

AMESim液压培训PPT课件

▪ 两种压力损失都能通过类似的流量方程(伯努利方程)计算
121020/3/23
O阻r尼ific孔es
U1
U2
U3
其中
Px = 静压 U = 流速
A = 过流面积
g = 重力加速度
P1 A1
P2 A2
P3 A3
h = 高度 ρ = 密度
atic
g h3
gravity
129020/3/23
O阻r尼ific孔es
▪ 复制前面的模型 ▪ 选择‘restriction definition’选项
▪ 使用之前的Q 和P 值分别作为流量和压降参数
▪ 比较两种不同的阻尼孔
03_simple_orifice.ame
2020/3/23
阻尼孔直径/ 最大流量系数
压降/流量
O阻r尼ific孔es
压
力
Psat
只有液体
吸收空气(全部或部分自由空气溶解空气)
饱和压力
空气析出(溶解游离)
Pvap
52020/3/23
+
空气气泡
挥发气泡
蒸发压力
时间
在AMESim 中定义液体属性
▪ 在草绘阶段，插入一个流体属性图标, 一个压力源和一个液体属性传感器。这是一种最简单的测试液体属性的方法
▪ 选择FP04 子模型(FP01, FP02 和 FP03 是以前旧版本所使用的现在被 FP04代替)
▪ 进入到参数阶段
62020/3/23
IT液nydp体eex性ooff质fhluy类idr型paurolipcefrlutiieds
液压油索引号是识别液体属性的参数，这样能够在同一个系统中考虑多种不同液体的影响（例如:液压油和冷却剂或液压油和汽油）。在草绘阶段, 必