机械原理(双语)第一章

For example, coupler is the rigid assembly(装配 体) of the ) coupler body, big-end cover, nuts, and bolts.
The crank 4, the pinion 4′, the flywheel 4″, and the keys(键), form another link.
Coupler 3 Crank 4 Frame 1
Pinion 4'
Gear 5
Cam 5'
Follower 6 Frame 1
Frame 1 Cam 5" Follower 7 Frame 1
Байду номын сангаас
Cam mechanism
凸轮机构
1 6
5'
Piston 2
Coupler 3 Crank 4 Frame 1
• “Design” is the process of prescribing the sizes, shapes, material compositions(成分), arrangements of parts, calculations of strength(强度), methods of production etc.
Study structure of internal combustion engine(内燃机) first.
1. Cylinder 缸体 or Frame 机架 2. Piston 活塞 3. Coupler 连杆 4. Crank 曲柄 4’. Pinion 小齿轮 4”. Flywheel飞轮 5. Gear 大齿轮 5’. Inlet cam进气凸轮 5”.Outlet cam排气凸轮 6. Inlet valve进气阀 7. Outlet valve排气阀
Difference between “synthesis(综合)” and “design” : Dimensions(尺寸) affecting(影响) the motion of the mechanism are called kinematics dimensions(运动学尺寸). Distance LAB between the centres of the two holes in the coupler is the only kinematics dimension.
Piston 2
Coupler 3 Crank 4 Frame 1
Slider-crank mechanism
曲柄滑块机构
1
2
3 4
Piston 2
Coupler 3 Crank 4 Frame 1
Pinion 4'
Gear 5
Frame 1
Gear mechanism
齿轮机构
5 1 4'
Piston 2
一般认为机器的研究重点是机械功和机 械能的问题；而机构的研究重点是在其结构、 运动和力作用等基本方面。 （1）人为的实物的组合体。 （2）各构件之间都具有确定的相对运动。 （3）能够完成有用的机械功或转换机械能。 凡同时具备以上3个特征的实物组合体就 称为机器。机构具有机器的前两个特征。 从结构和运动的观点来看，两者之间并无 区别。因此，常用“机械”一词作为它们的 总称。
齿轮机构
Cam mechanism
凸轮机构
1 6
5
3 4
1
4'
5'
Mechanism(机构) is a basic system of links(构件) which can transform(转换) or transmit(传递) force and motion. The function of the slider-crank mechanism is to transform the reciprocation(往复移动) of the piston 2 into the rotation of the crank 4. The function of the gear mechanism is to change the direction and speed of rotation. The function of the cam mechanism is to transform the continuous rotation of the cam into a regular reciprocation of the follower.
The gear 5, the cam shaft(轴) (including the two cams 5’ and 5”) , and the key form a third link.
In the study of kinematics(运动学), we are concerned only with the motion of links(构件), not of individual(单个) machine elements(零件).
Machine(机器) is a mechanical system which can transmit or transform energy, materials or information. Many practical machines contain more than one mechanism while many simple machines are composed(组成) of only one basic mechanism. The term ″machinery″ (机械) is used to cover both mechanisms and machines. The study object of this book is machinery.
A (a) A A
(b)
B
B B
Difference between “synthesis(综合)” and “design” : Dimensions(尺寸) affecting(影响) the motion of the mechanism are called kinematics dimensions(运动学尺寸). The radius of the hole is not a kinematics dimension!!!!!
Other machines: the shaping machine ….
Composition(组成) of machine
从功能和系统的角度来看，机器一般主要由五 部分组成。
操纵系统和控制系统 动力系统 传动系统 框架支撑系统 执行系统
1.2 Study Content ：
Most machines, even very complicated(复 杂的) ones, are built up from only a few types of commonly used mechanisms, such as slidercrank mechanisms, gear mechanisms, cam mechanisms etc. This situation(情形) is similar to the combinations(组合) of the seven-piece puzzle(七巧板). The most content of this book is for “analysis(分析)” and “synthesis(综合)” of some commonly used mechanisms.
Pinion 4'
Gear 5
Cam 5'
Follower 6 Frame 1
Frame 1 Cam 5" Follower 7 Frame 1
This is a structural block diagram (结构框 图) of inter ternal ter combustion engine（内
1.3 Purpose It is hoped that, after studying this textbook, the student will grasp(掌握) the basic theory and obtain the basic knowledge and skills(技能) needed in mechanisms synthesis and kinematic and dynamic(动力学的) analysis of machinery. The knowledge to be obtained from this textbook is therefore fundamental(基本的) in analyzing existing(现有的) machines and designing new ones.
Piston 2
Coupler 3 Crank 4 Frame 1
Pinion 4'
Gear 5
Cam 5'
Follower 6 Frame 1
Frame 1 Cam 5" Follower 7 Frame 1
Slider-crank mechanism
曲柄滑块机构
1
2
Gear mechanism
A (a) A A
(b)
B
B B
• “Synthesis (综合)” is the process of determining only the kinematics dimensions of a mechanism required to produce a particular (特定的) motion.
燃机）
Machine element(零件) is a basic element（元素） of manufacture（制造）, e.g. coupler body, big-end cover, nuts（螺母）, bolts（螺栓） etc. .
Link(构件) is a basic element in kinematic analysis(运动分析). It may be a rigid(刚性的) structure of some machine elements.
机构与机器理论 (机械原理)
Mechanisms and Machine Theory
Ye Zhonghe Lan Zhaohui M.R. Smith
Chapter 1
Introduction 1.1 Study Object (对象): Machinery(机械) (1)Machine and Mechanism(机构):
Piston 2
Coupler 3 Crank 4 Frame 1
Pinion 4'
Gear 5
Cam 5'
Follower 6 Frame 1
Frame 1 Cam 5" Follower 7 Frame 1
Mechanism(机构) is a system of links(构件) which can transform(转换) or transmit(传递) force and motion.