家用轿车（长安悦翔）真空助力器的改进设计【全套包含CAD图纸、三维建模、毕业论文说明书】
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全套包含CAD图纸、三维建模、毕业论文说明书
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真空助力器工作原理 在非工作的状态下,控制阀推杆回位弹簧将控制阀推杆推到右边的锁片锁定位置, 真空阀口处于开启状态,控制阀弹簧使控制阀皮碗与空气阀座紧密接触,从而关闭了空气阀口。此时助力器的真空气室和应用气室分别通过活塞体的真空气室通道与应用气室通道经控制阀腔处相通,并与外界大气相隔绝。发动机启动后, 发动机的进气歧管处的真空度（发动机的负压）将上升至-0.0667MPA（即气压值为0.0333MPA，与大气压的气压差为0.0667MPA）。随之，助力器的真空、应用气室的真空度均上升至-0.0667MPA，并处于随时工作的准备状态。 当进行制动时,制动踏板被踏下,踏板力经杠杆放大后作用在控制阀推杆上。首先, 控制阀推杆回位弹簧被压缩,控制阀推杆连同空气阀柱前移。当控制阀推杆前移到控制阀皮碗与真空阀座相接触的位置时,真空阀口关闭。此时，助力器的真空、应用气室被隔开。此时，空气阀柱端部刚好与反作用盘的表面相接触。随着控制阀推杆的继续前移,空气阀口将开启。外界空气经过滤气后通过打开的空气阀口及通往应用气室的通道,进入到助力器的应用气室(右气室),伺服力产生。由于反作用盘的材质（橡胶件）有受力表面各处的单位压强相等的物理属性要求，使得伺服力随着控制阀推杆输入力的逐渐增加而成固定比例(伺服力比)增长。由于伺服力资源的有限性,当达到最大伺服力时,即应用气室的真空度为零时(即一个标准大气压),伺服力将成为一个常量，不再发生变化。此时，助力器的输入力与输出力将等量增长；取消制动时,随着输入力的减小，控制阀推杆后移。当达到最大助力点时，真空阀口开启后,助力器的真空、应用气室相通,应用气室的真空度将下降,伺服力减小,活塞体后移。就这样随着输入力的逐渐减小,伺服力也将成固定比例(伺服力比)的减少,直至制动被完全解除。真空助力器的核心尺寸链在助力器的设计中，核心尺寸链的设计是保证助力器工作性能的关键，其中最为关键的尺寸配合是空气阀柱长度 与真空阀座到反馈盘主面的距离 （对于双膜片的助力器来说， 是指真空阀口到活塞体凸台上端面的距离与轴套同凸台相接触的端面到轴套同反馈盘表面相接触的端面距离之和）和控制阀的真空阀口处的形变量 之间的配合关系。在上述的理想状态工作过程的叙述中，我们可以注意到在理想的工作状态下的当空气阀口到达打开的瞬间位置时，空气阀柱端部应刚好与反作用盘接触，可以看出在理论上成立的状态在现实中是不可能实现的。第一，每个零件的尺寸是有它的尺寸公差带；第二，大量部件的生产是符合统计规律的，实际的尺寸区间是一个公差带，而理想的位置只是在公差带上的一个点而已。那么，在实际设计中，是如何处理这个矛盾的。其核心的尺寸链的配合采取的是间隙配合。也就是说，当空气阀口打开的时候，空气阀柱的端部没有到达反作用盘的接触面上，存在一定的间隙。在实际设计中，为取得良好的始动力和释放力等技术参数，采用了间隙配合。真空助力器的三个重要的工作原理目前关于真空助力器的文献中，都只是提到了真空助力器的三个工作状态，即应用状态、维持状态、释放状态。并指出在这三种状态下，真空阀口和空气阀口的处于开或合的状态。除了在上述提到的基本原理以外, 又发现了在国内文献中未曾提及的几个重要原理, 即, 三个平衡位置的原理、平衡位置的动态转换的原理和反作用盘的核心作用。真空助力器的阀口的三个平衡位置的原理汽车真空助力器在工作过程中存在着三个平衡位置，在加载时（或制动时）空气阀口处于若即若离状态，此时控制阀在空气阀口处无形变，而真空阀口处于关闭状态，控制阀在真空阀口处有形变；在卸载时（或取消制动时）真空阀口处于若即若离的状态，此时控制阀在真空阀口处无形变，而空气阀口处于关闭状态，控制阀在空气阀口处有形变；当制动稳定在某一时刻，输入力不再变化时（即助力器处于无运动趋势的状态），空气阀口和真空阀口均处关闭状态，控制阀在真空阀口处和空气阀口处均有形变。这就是助力器在工作状态下的三个平衡位置。真空助力器平衡位置的动态转换的原理助力器在工作过程中的平衡位置的动态转换的原理。这是一个极容易被忽视的原理，也是在结构和工艺设计时必须考虑到的重要原理。当加载结束的瞬间，助力器将由加载平衡位置向制动稳定态平衡位置转换，即控制阀在空气阀口由无形变向有形变转换。此时，空气阀口的结构设计及加工质量是否能够保证密封性的要求将受到严格的考验；当卸载开始的瞬间，助力器将由制动稳定态平衡位置向卸载平衡位置转换，即控制阀在真空阀口由有形变向无形变转换。此时，真空阀口的结构设计及加工质量是否能够保证密封性的要求将受到严格的考验。 实际的真空助力器的工作过程由上述的阐述可以看到，实际的工作过程与理想的工作过程是有所不同的。在核心尺寸链为间隙配合的条件下，结合工作状态的三个平衡位置的理论。真空助力器的实际的工作过程是：制动时,制动踏板被踏下。踏板力经过杠杆的放大后作用在控制阀推杆上。首先,推杆回位弹簧被压缩,控制阀推杆连同空气阀柱前移。当控制阀推杆前移到控制阀皮碗与真空阀座相接触的位置时,真空阀口关闭，控制阀的真空阀口处从刚刚接触直到产生形变。此时，真空、应用气室被隔开,控制阀推杆继续前移使得空气阀口处于即将开启状态。此时，控制阀的空气阀口处已经没有形变。此处是助力器升压时的平衡位置，此时空气阀柱端部还没有与反作用盘的主面相接触。随着控制阀推杆的继续前移,空气阀将开启。外界空气经过滤气后通过打开的空气阀口及通过到应用气室的通道,进入到助力器的应用气室(右气室),伺服力产生。由于反作用盘的主面没有与控制阀的端部接触，因此，助力器还没有达到平衡。而空气进入到应用气室产生的伺服力使得反作用盘的副面受力，于是反作用盘的主面隆起，直到副面上产生的伺服力的大小使得主面隆起的高度达到与控制阀的端面接触时，助力器初始平衡位置建立。然后，随控制阀推杆输入力的逐渐增加而伺服力成固定比例(伺服力比)增长。由于伺服力资源的有限性,当达到最大伺服力时,即应用气室的真空度为零时(应用气室气压为一个大气压),伺服力将不再发生变化。此时助力器的输入力与输出力将等量增长，隆起的主面将在控制阀力的作用下，逐渐减小隆起的高度，当达到足够到的输入力时，反作用盘的主面甚至开始下凹，此时的空气阀口处打开的间隙越来越大，助力器的应用气室与外界空气完全相通；取消制动时,随着输入力的减小，控制阀推杆后移，伺服力仍然是个固定值，控制阀口开启的间隙越来越小直到退后到空气阀口刚好关闭并随之产生形变。注意此处的位置并不是降压过程的平衡位置。随着输入力的继续减小,真空阀口将处于即将开启的状态，此时的真空助力器的控制阀才处于降压过程中的平衡位置。我们注意到升压时的平衡位置与降压时的平衡位置存在一个的差值，这个差值就是控制阀在真空阀口和空气阀口处的两个形变值的和，即 。由于核心尺寸链是间隙配合，此差值使得反作用盘在助力器降压过程中需要更大隆起高度来实现平衡。真空阀口开启后,助力器的真空、应用气室相通,应用气室的真空度将下降,伺服力减小,活塞体后移。在连续的降压过程中，控制阀的空气阀口处始终有形变，而控制阀的真空阀口一直处于无形变（即若即若离的状态）。直到反作用盘的主面作用力接近为零。此时，助力器达到了最后的平衡位置。如果控制阀推杆继续后退，助力器的平衡被打破，恢复到初始的状态。 这就是真空助力器的一次密封检验(或者说，一次常规的制动过程)中真空助力器工作的详细过程，了解这个过程对于理解真空助力器的特性曲线的各性能参数的理解是至关重要的。在第3章的真空助力器的性能参数的计算中，就是依据此过程来得到的。而没有使用间隙配合的真空助力器的性能参数的计算和曲线以及产生的后果将在第4章中作详细的讨论。 应该特别注意的两个概念是：在一台设计合理的真空助力器实际工作过程中，应该存在初始平衡位置和最后平衡位置这两个概念。在输入力-输出力的特性曲线中,两个平衡位置的力学关系的体现分别对应的是始动力和释放力处跳跃值变化的过程。真空助力器两个平衡位置的概念初始平衡位置的概念：在升压过程中，空气阀口开启的同时，空气阀柱端部未能触到反作用盘上，即合理的间隙配合。这样空气阀口打开，应用气室进气，伺服力产生。于是，反作用盘的副面受力，反作用盘发生形变，主面将隆起，直到隆起的主面与空气阀端部接触，才达到一个稳定的平衡。在此过程中由于伺服力的增大，使输出力（或液压）在输入力不变的情况下增加。最后平衡位置的概念：在降压过程的末期，随着输入力的降低，当反作用盘主面的受力几乎为零时，助力器的输出力完全是由伺服力产生的。这个伺服力同时又保证着反作用盘的形变。此时，如果控制阀推杆继续后移，由于制动主缸不能产生足够的抗力与残留的伺服力相平衡，使反作用盘不能产生足够的起补偿作用的形变量，以保持助力器的平衡，则助力器将失去平衡状态。其后，真空阀口将被打开，伺服力被释放，反作用盘上的形变消失，助力器恢复到起始状态。由于加载时和卸载时的控制阀阀口的平衡位置转变，可以知道，助力器释放力处的跳跃值应该大于始动力时的跳跃值。反作用盘的核心作用和性能要求 在真空助力器的工作过程中，反作用盘起着极其重要的作用。真空助力器的工作原理要求，当空气阀口开启的瞬间，空气阀柱端面要刚好触到反作用盘的主面上。又由于反作用盘的材质有要求受力表面各处压强相等的特性，使得伺服力随着控制阀推杆输入力的逐渐变化而成固定比例(伺服力比)关系变化。反作用盘的主面与副面同时受力，且受力的大小与主面和副面的面积成正比。此时，助力器的随动性最好，反作用盘的使用寿命长。但是，这种理想状态在现实中是很难实现的。设计合理的助力器（间隙配合）的反作用盘又起到了补偿作用。当空气阀口开启的瞬间，空气阀柱端面没能触到反作用盘的主面上，它们之间还有一定的间隙。这时空气阀口开启，助力器的应用气室进气，产生伺服力，反作用盘的副面受力，主面将隆起。当主面隆起的高度能够补偿了空气阀柱与反作用盘主面之间的间隙时，助力器达到了平衡状态。反之，设计不合理助力器当空气阀柱端面触到反作用盘主面上时, 空气阀未能开启,这时反作用盘的主面由于受力而凹下，而副面相对隆起,直到反作用盘的副面隆起的高度能够使空气阀口开启时, 助力器才达到平衡状态。 反作用盘材质具有的这种即要求受力表面各处压强相等又能够产生形变的材质特征是真空助力器工作原理的核心原理之一。因此，对反作用盘的性能要求如下：良好的密封性。反作用盘的过盈量要适当，过盈量太小不能保证密封性；过盈量太大，反作用盘侧面的摩擦力加大,影响助力器的工作性能。良好的形变能力。反作用盘的材质和形状要有利于反作用盘的变形。The working principle of the vacuum boosterIn non-working condition, putting control valve return spring to push the valve push rod to the lock lock on the right position, the vacuum valve is fully open, the control valve spring make close contact with the air valve seat, valve skin bowl to shut down the air valve port. At this time of booster air chamber and a gas chamber, respectively, by the piston body true air chamber air chamber channel and application of channel by the valve cavity are interlinked, and isolated atmosphere with the outside world. The engine starts, the engine intake manifold of vacuum negative pressure (engine) will rise to 0.0667 MPA (i.e. air pressure value of 0.0333 MPA, the pressure difference between the atmospheric pressure and 0.0667 MPA). Then, booster air chamber the vacuum degree of vacuum, the application of up to 0.0667 MPA, and work at any time in the ready state.When carries on the brake, the brake pedal is stepped down, pedal force after leverage amplification effect on control valves putter. First of all, putting control valve return spring is compressed, control valves putter along with air valve column moved forward. When the control valve putting forward to the location of the control valve seat contact cup and vacuum, vacuum valve mouth closed. At this point, the vacuum booster, application chamber was separated. At this point, the air valve column end just and reaction plate surface in contact. As control valves putter continues forward, the air valve port will open. Outside air by opening the air valve port after filtered air and access to the developments in the application of air chamber into the application of the booster air chamber air chamber (right), servo power is generated. As a result of the reaction plate force around the surface of the material (rubber) have unit of pressure equal to the physical properties of a request, make the servo as control valves putter input forces increase gradually and become a fixed ratio (servo power ratio). Servo force due to the limited resources, when the maximum servo power, namely the application of air chamber of the vacuum is zero (that is, a standard atmospheric pressure), servo power will become a constant, no longer change. At this point, the booster of the input force and output force will increase amount; Cancel brake, with the decrease of the input power, control valves putter move backward. When the maximum power point, vacuum valve mouth open, after the vacuum booster air chamber interlinked, application, the application of air chamber vacuum will decline, servo power decreases, and the piston body backwards. So as the input force decreases, servo power will also be a fixed ratio (servo power ratio) reduction, until the brake is completely released.The core of the vacuum booster dimension chainIn the design of booster, the design of the core dimension chain is the key for ensuring the performance of the booster, is one of the most critical dimensions with air valve tray column length and the vacuum valve seat to feedback the distance of the primary side (for double diaphragm of the booster, is refers to the vacuum valve port to the end of the piston body convex platform distance convex platform in contact with shaft sleeve end to the shaft sleeve with feedback plate of the sum of transverse distance between the contact surface) and the control valve of the vacuum valve the cooperate relationship between the variables in the shape of mouth.In the working process of the ideal status of the above description, we can notice under the working state of ideal reversal valve to open the mouth of the moment, the air valve column should end just contact and reaction plate, it can be seen in theory established state in reality is impossible. First, the size of each part is it the size of the tolerance zone; Second, a large number of production of a part is in conformity with the statistical rule, the size of the actual interval is a tolerance zone, and the ideal position just in tolerance with a point. So, in the practical design, is how to deal with this contradiction. Its core with the dimension chains clearance fit. That is to say, the reversal valve opens mouth, air valve column that failed to reach the end of reaction plate contact surface, there is a certain gap. In actual design, to achieve good technical parameters such as dynamic and release force, adopted the clearance fit.The three important working principle of vacuum boosterThe current literature about vacuum booster, is mentioned three working state of the vacuum booster, namely, application state, maintain state, release status. And points out that in the condition of the three, vacuum valve and air valve opening is in a state of open or closed.In addition to the basic principle of the above mentioned, and found in domestic literature mentioned several important principle, that is, the equilibrium position of the three principle, the equilibrium position of the principle of dynamic conversion and the core of the reaction plate.Vacuum booster valve mouth of the three principle of equilibrium positionAutomobile vacuum booster in the process of work there are three equilibrium position, at the time of loading (or braking) the air valve port in the state of brinkmanship, the control valve in the air valve port intangible changes, and vacuum valve closed, control valve in the vacuum valve mouth deformation; When unloading or cancel when braking vacuum valve mouth is in a state of half, the control valve in the vacuum valve mouth intangible changes, and the air valve mouth closed, control valves in the air valve port deformation; When braking stability at some point, the input force no longer changes (i.e., booster is in a state of no movement trend), air valve and vacuum valve are closed, the control valve in the vacuum valve and air valve port in deformation. This is the booster in the working status of the three equilibrium position.The principle of vacuum booster equilibrium position of the dynamic transformationBooster in the working process of the equilibrium position of the principle of dynamic transformation. This is a very easy to be ignored principle, is also in the structure and process design must consider the important principle. When the moment, the end of the load to brake booster will load equilibrium position by steady-state equilibrium position transformation, namely the control valve in the air valve port from intangible variable to have deformation. At this point, the air valve port structure design and processing quality is to meet the requirements of sealing will be subject to strict test; When unloading began to moment, booster will balance position to uninstall from braking stability state equilibrium position transformation, namely the control valve in the vacuum valve port has a deformation by intangible variable transformation. At this point, the vacuum valve structure design and processing quality is to meet the requirements of sealing will be subject to strict test.The actual working process of the vacuum boosterBy the paper as you can see, the working process of the actual and ideal working process is different. Under the condition of the core dimension chain for the clearance fit, combined with the working state of the three theory of equilibrium position. The actual work process of vacuum booster is: brake, the brake pedal is stepped down. Pedal force after leverage amplification effect on control valves putter. First of all, the push rod return spring is compressed, control valves putter along with air valve column moved forward. When the control valve putting forward to the location of the control valve seat contact cup and vacuum, vacuum valve mouth shut, control valve of the vacuum valve mouth from just contact to produce deformation. At this point, the vacuum, the application of air chamber is separated, control valves putter continue forward air valve in the open. At this point, the control valve of the air valve mouth has no deformation. Here is the equilibrium position, when booster booster valve column end havent the space and time and the reaction plate of the primary side of the contact. As the control valves putter continue forward, air valve will open. Outside air after filtering air by opening the air valve port and through to the channel of the air chamber, into the application of the booster air chamber air chamber (right), servo power is generated. As a result of the reaction plate of primary side without contact with the end of control valve, therefore, booster havent reached balance. And air chamber into the application of servo force makes the reaction plate side force, so the reaction of primary side uplift, until the servo force produced by vice on the size of the primary side uplift altitude to come in contact with the end face of valve, booster to establish initial equilibrium position. Then, along with the increasing of control valves putter input force servo force into a fixed ratio (servo power ratio). Servo force due to the limited resources, when the maximum servo power, namely the application of air chamber of the vacuum is zero (application of gas chamber pressure for an atmospheric pressure), servo power will no longer be changed. Booster at this time of the input force and output force will increase amount, uplift of the primary side will be under the action of force control valve, gradually reduce the height of the uplift, when enough to the input power, reaction plate of the primary side and even began to sink, the air valve mouth opened the gap is more and more big, the application of the booster air chamber air completely interlinked with the outside world; Cancel brake, with the decrease of the input power, control valves putter move backward, servo power is still a fixed value, control valve mouth open gap smaller and smaller until back to the air valve port just shut down and the resulting deformation. Note here the position of the equilibrium position is not step-down process. As the input force continued to reduce, vacuum valve port will open in the state of vacuum booster valve just at this time in the equilibrium position in the process of decompression. We noticed that the equilibrium position when booster and step-down the equilibrium position when there is a difference, this difference is the control valve in the vacuum valve and air valve and two deformation value of the mouth, namely. As the core dimension chain is clearance fit, the difference makes the reaction plate in the process of booster step-down need more bulge height to achieve balance. After vacuum valve mouth open, the vacuum booster, the application of air chamber are interlinked, vacuum will decline the application of air chamber, servo power decreases, and the piston body backwards. In the process of continuous decompression, the control valve of air valve mouth always have deformation, vacuum valve and control valve mouth has been invisible (state) of brinkmanship. Until the primary side reaction plate force close to zero. At this point, the booster has reached the final equilibrium position. If the valve push rod continues to retreat, booster balance is broken, restore to the original state.This is a sealed vacuum booster test (or, a routine braking process) in the detailed process of vacuum booster work, get to know the process to understand the characteristic curve of the performance parameters of the vacuum booster understanding is very important. In chapter 3 of the calculation of performance parameters of vacuum booster, is based on the process to get. Without the use of clearance fit the calculation of performance parameters of the vacuum booster and curve, and the consequences will be discussed in detail in chapter 4.Should pay special attention to the two concepts are: on a reasonable design of the actual working process of the vacuum booster, there should be the initial equilibrium position and the final equilibrium position of these two concepts. In the characteristic of input - output forces, the embodiment of the two the mechanics relation between the equilibrium position correspond as starting power and release force jump value change process.The concept of vacuum booster two equilibrium positionThe concept of initial equilibrium position: in the process of booster, the air valve port open at the same time, the air valve department failed to touch at the end of the reaction plate, namely the reasonable clearance fit. This air valve to open the mouth, a gas chamber inlet, servo power is generated. Vice surface stress and reaction plate, reaction plate deformation occurs, god will uplift, until the uplift of the primary side in contact with the air valve ends, to reach a stable equilibrium. In this process because of the servo power increase, make the output force (or hydraulic) under the condition of invariable in the input force increases.The final equilibrium position of concept: in the late step-down process, with the loss of the input force, when the stress of the reaction plate of primary side almost to zero, the output of the booster force is produced by the servo power. The servo power at the same time guarantee the reaction plate deformation. At this point, if the valve push rod continues to move backward, because the brake master cylinder does not produce enough resistance and residual servo power phase equilibrium, the reaction plate does not produce enough compensation effect of variables, to maintain the balance of the booster, the booster will lose balance. Followed by vacuum valve will open mouth, servo power is released, the reaction plate deformation disappear, booster recovery to the initial state. Because at the time of loading and unloading valve valve mouth of the equilibrium position shift, can know, booster release force of the dynamic value should be greater than the starting time of the value of jumping.The core of the reaction plate of function and performance requirementsIn the process of the vacuum booster, reaction plate plays an extremely important role. The working principle of vacuum booster, reversal valve mouth open, air valve column face to just touch the reaction on the primary side. And as a resu
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