盤式制動(dòng)器制動(dòng)系統(tǒng)原理外文文獻(xiàn)翻譯、中英文翻譯、外文翻譯

1、45.1 制動(dòng)系統(tǒng)原理摩擦力摩擦力的定義為抵抗兩個(gè)物體之間相對(duì)運(yùn)動(dòng)的一種力。當(dāng)兩個(gè)面接觸在一起，并產(chǎn)生相對(duì)運(yùn)動(dòng)時(shí)，就會(huì)產(chǎn)生摩擦力（如圖45-1） 。摩擦力的大小取決于兩點(diǎn)：物體的表面粗糙度和兩接觸面之間所受壓力的大小。圖 45-1 當(dāng)兩個(gè)物體表面接觸到一起時(shí)，就會(huì)產(chǎn)生摩擦力。制動(dòng)系統(tǒng)就是通過(guò)產(chǎn)生摩擦力來(lái)使汽車停止運(yùn)動(dòng)或者減速行駛的。熱能當(dāng)發(fā)生摩擦運(yùn)動(dòng)運(yùn)動(dòng)時(shí)，動(dòng)能（運(yùn)動(dòng)中的能量）就會(huì)轉(zhuǎn)化為熱（熱）能量。動(dòng)能越大，產(chǎn)生的熱量就越多，因此必須要有足夠的間歇時(shí)間來(lái)散發(fā)熱量。汽車在運(yùn)動(dòng)產(chǎn)生中產(chǎn)生的能量的大小，或者稱之為動(dòng)能大小，主要取決于汽車的重量和汽車行駛的速度。因此，剎車時(shí)必須要盡量減少熱量的產(chǎn)生。

2、摩擦力和制動(dòng)系統(tǒng)在任何制動(dòng)系統(tǒng)中，摩擦力的大小是由控制器控制的。通過(guò)改變摩擦力，可以使汽車停止運(yùn)動(dòng)，而且汽車在不同的行駛條件下，汽車的速度大小可以隨坐標(biāo)曲線而變化。摩擦力的控制是通過(guò)一個(gè)固定的制動(dòng)蹄或是制動(dòng)板，傳遞給一個(gè)旋轉(zhuǎn)的制動(dòng)鼓或者是制動(dòng)盤。當(dāng)駕駛員踩在制動(dòng)腳踏板上的力增大時(shí)，摩擦力也會(huì)隨之曾加。在制動(dòng)摩擦力的作用下，車輪會(huì)逐漸停止轉(zhuǎn)動(dòng)，輪胎也會(huì)隨之停止轉(zhuǎn)動(dòng)。然而，輪胎和地面之間也會(huì)產(chǎn)生摩擦力。制動(dòng)器上產(chǎn)生的摩擦力必須與輪胎與地面之間產(chǎn)生的摩擦力大小相匹配。如果與地面接觸的輪胎不能產(chǎn)生摩擦力，就會(huì)產(chǎn)生車輪鎖死和車輪打滑的現(xiàn)象。如果車輪不產(chǎn)生鎖死的現(xiàn)象，汽車會(huì)更安全可靠的停止運(yùn)動(dòng)。車輪在鎖死

3、的情況下會(huì)產(chǎn)生非常危險(xiǎn)的后果，尤其是在沒有驅(qū)動(dòng)控制的輪胎和路面之間產(chǎn)生摩擦。為了控制任何一個(gè)車輪在減速時(shí)出現(xiàn)打滑的現(xiàn)象，人們已經(jīng)開始廣泛使用電腦控制的制動(dòng)器。鼓式制動(dòng)器的基本操作原理鼓式制動(dòng)器大致是由一個(gè)用螺栓固定在車輪上的鑄造鼓構(gòu)成的，而且鑄造鼓也可以隨車輪一起轉(zhuǎn)動(dòng)。在鑄造鼓的內(nèi)部有一個(gè)依靠一套制動(dòng)蹄連接的制動(dòng)板。鑄造鼓內(nèi)的其它部分也是連接在制動(dòng)板上的，包括一個(gè)液壓缸，以及一些彈簧和連接桿。制動(dòng)蹄和摩擦材料連接在一起。當(dāng)制動(dòng)器工作時(shí)，摩擦材料就會(huì)貼附在制動(dòng)鼓的內(nèi)表面（圖45-2）制動(dòng)器一旦開始工作，制動(dòng)蹄就會(huì)在力的作用下緊貼在制動(dòng)鼓的內(nèi)表面，從而產(chǎn)生摩擦力。圖 45-2 在一個(gè)鼓式制動(dòng)系統(tǒng)中

4、，制動(dòng)蹄被強(qiáng)制向外壓緊在制動(dòng)鼓上，從而產(chǎn)生所需的摩擦力。制動(dòng)蹄的激勵(lì)原理當(dāng)剎車系統(tǒng)開始工作時(shí)，制動(dòng)蹄的自己離作用是很重要的。當(dāng)剎車制動(dòng)作用時(shí)，在摩擦力的帶動(dòng)作用下，制動(dòng)蹄就會(huì)繞著制動(dòng)蹄樞軸點(diǎn)旋轉(zhuǎn)，就像圖45-3 所示的那樣。當(dāng)制動(dòng)蹄和制動(dòng)鼓旋轉(zhuǎn)的方向一致時(shí)，主制動(dòng)蹄和副制動(dòng)蹄產(chǎn)生的摩擦力，就會(huì)使得制動(dòng)蹄緊緊地貼附在制動(dòng)鼓的內(nèi)表面。這種現(xiàn)象就被稱作是制動(dòng)蹄的自激勵(lì)作用。圖 45-3 當(dāng)制動(dòng)系統(tǒng)工作時(shí)，主制動(dòng)蹄會(huì)先做出反應(yīng)。然后主制動(dòng)蹄會(huì)推動(dòng)副制動(dòng)蹄向相反方向運(yùn)動(dòng)。伺服式制動(dòng)器伺服式制動(dòng)器就是一種把一個(gè)相對(duì)較小的力轉(zhuǎn)化為一個(gè)較大的力的一種設(shè)備。在當(dāng)今大部分汽車當(dāng)中，伺服式制動(dòng)器被用來(lái)依靠液壓缸內(nèi)部

5、的一種液壓力來(lái)引導(dǎo)制動(dòng)蹄向外運(yùn)動(dòng)。這種壓力是來(lái)自于操縱者的腳。這種作用將會(huì)推動(dòng)制動(dòng)蹄向外運(yùn)動(dòng)，致使制動(dòng)蹄緊緊地貼附在制動(dòng)鼓上。主制動(dòng)蹄和副制動(dòng)蹄的工作原理在一個(gè)鼓式制動(dòng)器的系統(tǒng)當(dāng)中，有一個(gè)主制動(dòng)蹄和一個(gè)副制動(dòng)蹄，就像圖45-3 所示的那樣。當(dāng)剎車系統(tǒng)開始工作時(shí)，主制動(dòng)蹄先做出反應(yīng)。在這里面會(huì)產(chǎn)生一個(gè)較弱的回位彈力。制動(dòng)蹄就會(huì)離開原來(lái)的位置，然后就會(huì)貼在制動(dòng)鼓的表面。當(dāng)制動(dòng)蹄接觸到制動(dòng)鼓的表面時(shí)，制動(dòng)蹄就會(huì)產(chǎn)生激勵(lì)，強(qiáng)制制動(dòng)蹄緊緊地旋附在制動(dòng)鼓上，從而導(dǎo)致摩擦力迅速增大。在這期間，副制動(dòng)蹄也會(huì)做出反應(yīng)。當(dāng)主制動(dòng)蹄開始運(yùn)動(dòng)時(shí)，主制動(dòng)蹄就會(huì)推動(dòng)或者把副制動(dòng)蹄移動(dòng)到制動(dòng)鼓的底部。這個(gè)動(dòng)作就會(huì)使得副制動(dòng)

6、蹄隨制動(dòng)鼓在同一個(gè)方向上運(yùn)動(dòng)。我們會(huì)注意到，副制動(dòng)蹄將不會(huì)再向上運(yùn)動(dòng)，因?yàn)樗鼤?huì)被強(qiáng)制的固定在這個(gè)位置上。這個(gè)動(dòng)作也會(huì)導(dǎo)致副制動(dòng)蹄產(chǎn)生激勵(lì)的作用。伺服制動(dòng)系統(tǒng)就會(huì)發(fā)生作用，從而在制動(dòng)蹄上產(chǎn)生出一個(gè)連續(xù)的作用。來(lái)自液壓缸內(nèi)的驅(qū)動(dòng)力只能推動(dòng)一個(gè)制動(dòng)蹄。通常液壓缸會(huì)產(chǎn)生一個(gè)很小的壓力來(lái)推動(dòng)制動(dòng)蹄工作。然而，由于制動(dòng)器的激勵(lì)作用，除了制動(dòng)蹄與制動(dòng)鼓的運(yùn)動(dòng)方向相反以外，這種力是不存在的。盤式制動(dòng)器的基本操作原理在許多汽車當(dāng)中，盤式制動(dòng)器和鼓式制動(dòng)器是合在一起使用的。在許多汽車中，盤式制動(dòng)器通常被用在汽車的前輪上，然而鼓式制動(dòng)器會(huì)被用在汽車的后輪上。盤式制動(dòng)器通常也會(huì)安裝在十速自行車上使用。這種制動(dòng)器的摩擦

7、力是由剎車片產(chǎn)生的，就像圖45-4 所示的那樣。剎車片被擠壓，或者是夾緊在正在旋轉(zhuǎn)的制動(dòng)盤上。剎車盤有時(shí)也會(huì)被稱作是轉(zhuǎn)子，會(huì)被安裝在輪輞上和輪胎上。轉(zhuǎn)子是由生鐵制作而成的，通常會(huì)被安裝在機(jī)器的兩邊。剎車片是被安裝在金屬板上的，他是靠液壓缸內(nèi)的活塞驅(qū)動(dòng)的。圖 45-4 在盤式制動(dòng)系統(tǒng)中，通常會(huì)使用兩個(gè)剎車片作用在一個(gè)轉(zhuǎn)子上，從而產(chǎn)生停車所需要的摩擦力。制動(dòng)鉗的工作原理在盤式剎車系統(tǒng)中，活塞被安裝在制動(dòng)鉗的上。制動(dòng)鉗是不會(huì)旋轉(zhuǎn)的，因?yàn)樗前惭b在汽車上的一部分固定結(jié)構(gòu)。制動(dòng)鉗是一個(gè)裝載著包括液壓活塞和液壓缸的殼體。制動(dòng)鉗的結(jié)構(gòu)還包括密封圈、彈簧和用來(lái)使活塞和制動(dòng)片產(chǎn)生運(yùn)動(dòng)的通道。剎車片在轉(zhuǎn)子上的作用

8、力是垂直于轉(zhuǎn)子旋轉(zhuǎn)方向的（如圖45-5） 。這是不同于鼓式制動(dòng)剎車系統(tǒng)的。盤式制動(dòng)器被認(rèn)為是沒有自激勵(lì)系統(tǒng)的。這就意味著在同一個(gè)制動(dòng)過(guò)程中，它需要獲得更大的制動(dòng)力。正是由于這個(gè)原因，盤式制動(dòng)器通常被用在動(dòng)力驅(qū)動(dòng)輪的制動(dòng)上。1945-5 在盤式制動(dòng)系統(tǒng)中，剎車片的作用方向是垂直于轉(zhuǎn)子的。固定式制動(dòng)鉗的設(shè)計(jì)方案這里有兩種制動(dòng)鉗的設(shè)計(jì)方案：固定式制動(dòng)鉗和浮動(dòng)式45-6 為我們展示了固定式制動(dòng)鉗的設(shè)計(jì)方案。圖 45-6 固定式制動(dòng)鉗是保持固定不動(dòng)的，它是靠剎車片向里或者是向外運(yùn)動(dòng)來(lái)產(chǎn)生摩擦力的。浮動(dòng)式制動(dòng)鉗的設(shè)計(jì)方案在浮動(dòng)式制動(dòng)鉗的設(shè)計(jì)方案中，制動(dòng)鉗的主殼體是允許45-7 就為我們展示里浮動(dòng)式制動(dòng)鉗的

9、設(shè)計(jì)思路。45-7 浮動(dòng)式制動(dòng)鉗是允許在支撐架上向內(nèi)或是向外運(yùn)動(dòng)一小段距離的。在這個(gè)系統(tǒng)中只有一個(gè)活塞。制動(dòng)液制動(dòng)液在制動(dòng)系統(tǒng)中扮演了一個(gè)重要的角色。在任何一個(gè)制動(dòng)過(guò)程中，制動(dòng)液用于將操縱者腳上的力傳遞到液壓缸和活塞上。制動(dòng)液是不能夠被壓縮的，然而氣體是可以被壓縮的，就像圖45-8 展示的那樣。隨著壓力的增加，任何在液壓制動(dòng)系統(tǒng)中的空氣就會(huì)受到壓縮，從而減小系統(tǒng)中所需要傳遞的力。這就是為什么要把液壓系統(tǒng)中的空氣趕出去的重要原因。為了達(dá)到這個(gè)目的，必須要把制動(dòng)系統(tǒng)中的空氣驅(qū)除出去。這個(gè)過(guò)程被稱作是制動(dòng)系統(tǒng)的放氣過(guò)程。圖 45-8 制動(dòng)液在剎車系統(tǒng)中得到使用是因?yàn)樗荒鼙粔嚎s的。然而氣體是可以被壓

10、縮的，所液壓系統(tǒng)的工作原理在汽車的制動(dòng)系統(tǒng)中是通過(guò)液壓系統(tǒng)來(lái)傳遞操縱者腳上的力，使之變?yōu)閮蓚€(gè)物體表面的摩擦力。在圖45-9 中，當(dāng)制動(dòng)腳踏板被踩下的時(shí)候，就會(huì)使得液壓缸內(nèi)產(chǎn)生一個(gè)壓力。這個(gè)壓力就會(huì)通過(guò)液壓線路傳遞到各個(gè)車輪的液壓缸內(nèi)。我們會(huì)注意到，在整個(gè)45-9 當(dāng)駕駛員踩下制動(dòng)踏板時(shí)，液壓系統(tǒng)的壓力隨之增加，而且壓力會(huì)被傳遞到每一個(gè)液壓缸內(nèi)來(lái)操控制動(dòng)系統(tǒng)。動(dòng)力和壓力在整個(gè)封閉的液壓系統(tǒng)中，剎車和活塞兩者之間的力，有一種特殊的關(guān)系。如果一個(gè)大小為100 磅的力作用在一個(gè)面積為1 平方英尺的活塞上面，那么在每平方英寸上將會(huì)產(chǎn)生 100磅的壓力。也就是說(shuō)，如圖45-10 所示的那樣，如果在這個(gè)液壓

11、系統(tǒng)中有其他的活塞，他們將會(huì)因?yàn)槌叽绲牟煌a(chǎn)生一個(gè)大小不等的壓力。一個(gè)尺寸為1/2 平方英寸的活塞能產(chǎn)生一個(gè)50 磅力。一個(gè)1 平方英寸的活塞上會(huì)產(chǎn)生一個(gè)100 磅的力。一個(gè) 2 平方英寸的活塞會(huì)產(chǎn)生一個(gè)200 磅的力。這個(gè)例子告訴我們，在一個(gè)大小確定的力作用在一個(gè)液壓系統(tǒng)中將會(huì)產(chǎn)生大小不同的力的作用，這主要是一句活塞面積的大小而定的。在液壓系統(tǒng)中，制動(dòng)液只會(huì)做非常微小的運(yùn)動(dòng)。制動(dòng)系統(tǒng)中，只是依靠動(dòng)力和壓力來(lái)工作的。在實(shí)際工作過(guò)程中，制動(dòng)液僅僅是被用作于把操作者腳上產(chǎn)生的動(dòng)力和壓力傳遞到活塞和摩擦盤上。45-10 液壓系統(tǒng)中的壓力會(huì)隨著活塞尺寸的不同而發(fā)生改變。P810-814)45.1 B

12、RAKING SYSTEM PRINCIPLESFRICTIONFriction is defend as a resistance to motion between two objects.When two surfaces rub against each other,there is friction (figure45-1).The amount of friction depends on two things:the roughness of the surfaces and the amount of pressure between the two surfaces.HEAT

13、 ENERGYWhen there is friction,kinetic energy (energy in motion) is converted to thermal (heat) energy.The greater the amount of kinetic energy that must be brought to rest,the greater the amount of heat produced.The energy of motion,or kinetic energy,depends on the weight of the vehicle and the spee

14、d of the vehicle.Brakes must also be able to remove the heat that is produced.FRICTION AND BRAKING SYSTEMSIn any braking system,the amount of friction is controlled by the operator.By varying friction,the vehicle can be stopped,and its speed can be modified on curves,grades,andi n different driving

15、conditions.Control of friction is obtained by forcing a stationary brake shoe or pad against a rotating drum or disc.As the driver presses harder on the brake pedal,friction increase.As the wheel is slowed down by the brake friction,the tire is also slowed down.However,friction is also produced betw

16、een the tire and the road.The friction on the brakes must be matched by the friction of the tires and the road.If the tires on the road cannot produce the frictions,the tires will lock up and skid.A car stops better if the wheels are not locked.Locked wheels can produce dangerous results,especially

17、since there is no driver control of the friction between the tires and the road.Computer-controlled brakes are also being used to control the slowing down of each wheel with-out skidding.BASIC OPERATION OF DRUM BRAKESA drum brake assembly consists of a cast drum that is bolted to and rotates with th

18、e wheel.Inside the drum,there is a backing plate that has a set of brake shoes attached to it.Other components are also attached to the backing plate,including a hydraulic cylinder and several springs and linkages.The brake shoes are lined with a frictional material.The frictional material contacts

19、the inside of the drum when the brakes are applied (Figure 45-2).When the brakes are applied,the brake shoes are forced out and produce friction against the inside of the drum.SHOE ENERGIZATIONWhen the brakes are applied,it is important for the shoe to be self-energizing.When the brake shoe is engag

20、ed,the frictional drag acting around the shoe tends to rotate the shoe about its pivot as shown in Figure 45-3.When the drum rotates in the same direction,the frictional drag between the two causes the shoe to become tighter against the inside of the drum.This action is called self-energizing.SERVO-

21、TYPE BRAKESA servo is a device that converts a relatively small force into a larger force.In most vehicles today,servo brakes are used to cause the brake shoes to move outward from a hydraulic pressure inside a cylinder.The pressure is produced by the operators foot.The motion is the outward push of

22、 the brake shoes against the drum.PRIMARY AND SECONDARY SHOE OPERATIONIn a drum brake system,there are primary and secondary shoes as shown in Figure 45-3.When the brakes are applied,the primary shoe reacts first.It has a weaker return spring.The shoe lifts off the anchor and contacts the drum surfa

23、ce.As the shoe begins to contact the drum,the shoe is energized,forcing it to rotate deeper into the drum,producing increased friction.During this time,there is also action on the secondary shoe.As the primary shoe moves,it tends to push or move the secondary shoe at the bottom.This motion forces th

24、e secondary shoe in the same direction as the drum.Note that the secondary shoe cannot move upward because it is forced against the anchor.This causes the secondary shoe to also be energized.The servo brake system acts or behaves as if it were one continuous shoe.The actuating force from the hydraul

25、ic cylinder pushes on only one shoe.A small amount of pressure is usually produced against the secondary shoe by the hydraulic cylinder.This force is not,however,used to energize the brakes,except in a reverse direction.BASIC OPETATION OF DISC BRAKESMany vehicles use disc brakes along with drum brak

26、es.On many vehicles,disc brakes areused on the rear wheels.Disc brakes resemble the brakes used on a ten-speed bicycle.The friction is produced by pads,as shown in Figure 45-4.These pads are squeezedo r clamped against a rotating disc.The disc,also called the rotor,is attached to the rim and tire.Th

27、e rotor is made of cast iron that is machined on both sides.The pads are attached to metal plates that are actuated by pistons from the hydraulic system.CALIPER OPERATIONThe pistons in a disc brake system are contained or held in place by the caliper.The caliper does not rotate because it is attache

28、d to the vehicles frame.The caliper is a housing that contains hydraulic pistons and cylinders.It also contains seals,springs,and fluid passages that are used to produce the movement of the piston and pads.The pads act perpendicular to the rotation of the rotor (Figure45-5).This is different from th

29、e drum brake system.Disc brakes are said to be non-self-energized.This means that they require more force to achieve the same braking effort.For this reason,disc brakes are usually used with power brakes.Fixed Caliper DesignThere are two types of caliper designs:the fixed caliper and the floating ca

30、liper.The fixed caliper design has the caliper assembly attached directly to the frame or steering components.Each pad is actuated by a piston.Figure 45-6 shows the fixed caliper design.Floating Caliper Design In the floating caliper design,the main housing of the caliper allows it to slide in and o

31、ut a small amount on the mountings.There is a piston on only one side.The other has only a friction pad.When the brakes are applied,the hydraulic pressure within the cylinder pushes the piston in one direction.The entire caliper housing is free to slide in the opposite direction.As the pads contact

32、the rotor,the force of the piston pad is matched by an equal force from the pad on the other side of the caliper.Figure 45-7 shows a floating caliper design.FLUIDSFluids play an important part in braking systems.Brake fluid is used to transfer the motion of the operators foot to the cylinders and pi

33、stons at each brake.Fluids cannot be compressed,while gases are compressible,as shown in Figure 45-8.Any air in the brake hydraulic system will compress as the pressure increases,which reduces the amount of force that can be transmitted.This is why it is very important to keep all air out of the hydraulic system.To do this,air must be removed from the brakes.This process is called bleeding the brake system.HYDRAULIC PRINCIPLESThe automotive braking system uses hydraulic pressure to transfer the force of the operators foot to press the friction surfaces together.In Fig