制動系統(tǒng)英文翻譯.doc

哈爾濱工業(yè)大學本科畢業(yè)論文（設計）翻譯資料 本科畢業(yè)論文（設計）翻譯資料論文題目CA1145P1貨車制動系統(tǒng)設計及強度分析 班 級1101203 姓 名范慶堯 院（系）汽車工程學院 導 師劉濤 - 13 -制動系統(tǒng)鼓式制動器鼓式制動器的制動是由一組制動蹄或者制動襯片壓緊旋轉(zhuǎn)制動鼓的內(nèi)表面而引起的摩擦。制動鼓和旋轉(zhuǎn)的車輪相連接。伺服系統(tǒng)設計鼓式制動器,由于制動蹄鉸接的方式,可以有一個“自動伺服”的特點。這使得在不增加駕駛者額外體力的情況下增加制動力，因為旋轉(zhuǎn)的制動鼓會拖拽周圍的制動蹄，從而加大了使他們靠在一起的力。在后制動器上只有一個蹄有這樣的特性。（前鼓式制動器也可能使用兩個驅(qū)動輪缸，這樣兩個蹄都可以利用伺服特性了，當然這也增加了前軸制動力，需要彌補向前轉(zhuǎn)移的載荷，與此同時也要避免后輪提前抱死。伺服現(xiàn)象可以用來制造一個非常大的制動作用(如大型商用車輛的后軸),但它確實降低了司機對制動的敏感度。(盤式制動器由于襯塊垂直地作用于制動盤而沒有自動伺服效果)。優(yōu)勢鼓式制動器仍使用在現(xiàn)代汽車中，因為它在技術和成本方面更占優(yōu)勢。駐車制動時用鼓式制動器結(jié)構(gòu)簡單。他們通常應用于后輪，因為大部分制動作用是由前輪產(chǎn)生的,因此后輪制動產(chǎn)生的熱量明顯減少。鼓式制動器有時也安裝在后輪以盤式制動器作為主要剎車的汽車上，起到駐車和緊急制動的作用。在這種情況下,小型制動鼓通常是安裝在剎車盤上或直接作為剎車盤的一部分。豐田普銳斯，一款技術先進的混合動力汽車，其后輪就采用鼓式制動器。(4輪皆盤式使用在一些特定市場混合動力汽車依靠能量回收，電動發(fā)電機，可見再生制動技術等大大減少日常制動系統(tǒng)的磨損)。缺點鼓式制動器內(nèi)部的制動蹄有一個特定的缺點：長時間急劇制動時會使得制動鼓溫度升高，其直徑會由于材料的膨脹而變大，制動蹄必須被更用力的壓緊來獲得有效的制動作用。這被稱為制動失效,可能導致司機恐慌，極端情況下甚至導致制動失效。在正常駕駛條件下，很少被注意到,特別是安裝的制動鼓尺寸適宜的時候。龐蒂亞克GTO的汽車因其使用較小尺寸的制動鼓而常被人們提起。剎車片在嵌入剎車片過程中，將高摩擦的剎車片材料嵌入到制動盤中，同事保證磨損均勻。雖然人們普遍認為是剎車片材料與制動盤表面金屬接觸才使汽車停下的，但其實是剎車片內(nèi)部一層很薄的材料產(chǎn)生了半液體摩擦邊界，從而產(chǎn)生了實際的制動力。當然，制動盤磨損的快慢取決于所用材料的特性。材料磨損特性的好壞是由性能和壽命之間的權衡來判定的。剎車片必須定期更換，大多數(shù)汽車都安裝了報警裝置，提醒駕駛者該更換剎車片了。有的是利用一片薄金屬片，當剎車片變得太薄時，引起制動尖叫。另一些將薄金屬片嵌入剎車片材料中，當剎車片變太薄時，會關閉電路，并點亮警示燈。更高級的汽車可能會使用電子傳感器。雖然幾乎所有的公路車輛每個制動鉗僅有兩個制動襯塊，但賽車卡鉗可利用多達6個制動襯塊，將不同的摩擦特性交錯布置，以獲得最佳的性能。早期的制動襯塊和制動蹄含有石棉。當修理老式汽車的制動器時，一定要小心，不要吸入制動鉗或制動鼓中的灰塵。制動尖叫有時當施加制動時，會出現(xiàn)很大的噪聲或者是高音調(diào)的尖叫。大部分制動尖叫是由于制動器部件尤其是制動襯塊和制動盤的振動（共振不穩(wěn)定）產(chǎn)生的。這種類型的制動尖叫不會對制動效能產(chǎn)生負面影響。一些簡單的技術，比如將襯片倒角，在制動鉗和制動襯塊之間加潤滑脂或者涂膠，在襯塊背板上粘貼絕緣體（阻尼材料）等，可以減輕制動尖叫現(xiàn)象。很多時候，寒冷的天氣加上清晨較大的濕度（露水）可能會夾具制動尖叫問題，尤其是當襯片達到常規(guī)操作溫度時，甚至會制動失效。然而也有些襯片磨損指示器被設計成當襯片需要更換時發(fā)出尖叫。整體看來，制動尖叫會給車輛內(nèi)的乘客、路人、行人等帶來煩擾，尤其是對那些以更舒適安靜為設計目標的車輛。因此整車NVH（噪聲，振動，不平順性）性能是當今汽車制造商最重要的考慮因素之一。制動器中的灰塵也可能引起制動尖叫。有許多商業(yè)制動器清潔產(chǎn)品，可用來清除制動器中的灰塵和污染物。一些高性能制動襯塊，比如鷹牌性能襯塊，在使用過程中會一直尖叫，但這并不表示有問題 。除了制動尖叫帶來的噪音之外，制動器也可能出現(xiàn)制動抖動或顫抖的現(xiàn)象。制動塵埃當施加制動力時，會逐漸地從制動襯塊上磨掉少許的材料。這些碎屑被稱為“制動粉塵”，通常會沉積在制動系統(tǒng)和周圍的車輪中。制動塵埃若不清除，將會嚴重損害大多數(shù)輪胎的使用。不同的制動摩擦片配方會產(chǎn)生不同數(shù)量的塵埃，有些配方相對于其他的更具破壞性。我們都知道踩下制動踏板會降低車速至停車，但這是怎么發(fā)生的呢？車輛是如何將你退步的力量傳遞到車輪上的呢？它是如何將力放大到足以讓像汽車那么大的物體停下來的呢？典型制動系統(tǒng)的布置當你踩下制動踏板，汽車通過液體將你腳下的力傳到制動器上。由于實際上制動器需要的力比人的腿部可以提供的大得多，因而汽車必須放大你腳上的力。有以下兩種方式：1 機械優(yōu)勢（杠桿作用）2 液力放大作用制動器靠摩擦力將力傳遞給車輪，同樣，車輪也是靠摩擦將力傳遞到路面。在我們開始討論制動系統(tǒng)的組成部分之前，我們將涵蓋以下三條原理：1杠桿作用2液壓3摩擦鼓式制動器和盤式制動器工作原理是一樣的：制動蹄壓緊在旋轉(zhuǎn)表面上。在此系統(tǒng)中，這個表面被稱為制動鼓。許多汽車后輪采用鼓式制動器，前輪采用盤式制動器。鼓式制動器較盤式的有更多零部件，而且制動效率更低，但它的制造成本較低，更容易安裝應急制動裝置。在部件如何運作這一版塊中，我們將清晰的了解到鼓式制動系統(tǒng)如何運作的，檢查緊急制動的設置，并找出需要什么樣的行車制動器。鼓式制動器可能看起來很復雜，當你打開一個的時候，可能會被嚇一跳。讓我們把它拆解開來，并一一解釋每個部分。和盤式制動器一樣，這個鼓式制動器有2個制動蹄，一個活塞輪缸。但鼓式制動器還有個調(diào)整裝置，應急制動裝置和一些彈簧。當踩下制動踏板，活塞將制動蹄壓向制動鼓。當制動蹄接觸到制動鼓上時，將會有一種楔入作用，它將起到使制動蹄以更大的力壓向制動鼓的作用。楔入作用提供的額外制動力使得鼓式制動器可比盤式制動器使用更小的活塞，然而，由于楔入作用，當釋放制動時，必須將制動蹄從制動鼓上拉離。其中一些彈簧就是為了這個原因。其他的彈簧負責使制動蹄還有起作用后的調(diào)整臂復位。制動器調(diào)整為使鼓式制動器正常工作，制動蹄必須和制動鼓保持接近，但又不接觸上它。如果它們離制動鼓太遠（例如制動蹄磨損太多），活塞就需要更多的液體來達到這個行程，當踩下剎車時，制動踏板將會更靠近地板。這就是 為何鼓式制動器需要自動調(diào)整裝置的原因。當制動襯片磨損時，制動蹄和鼓之間將會形成很大間隙。每次停車的背后，都是制動蹄壓緊制動鼓。當間隙大到一定程度，調(diào)整杠桿搖到足夠調(diào)整齒輪前進一個齒。調(diào)整器上有螺紋，就像個螺栓，當它轉(zhuǎn)動時，使其旋開一點點，旋到填補產(chǎn)生的間隙。當制動蹄再次磨損時，調(diào)整器繼續(xù)前進，因而它總是讓制動蹄靠近制動鼓。一些汽車的調(diào)整裝置在施加應急制動時被驅(qū)動。當應急制動器長時間不用時，這種類型的調(diào)整器也可單獨進行調(diào)整。要是你用的就是這種類型的調(diào)整器的話，你最好至少每周用一次你的應急制動器。維修對鼓式制動器最常需要的維修是更換制動蹄。一些鼓式制動器背面有個觀察孔。從那兒你可以看到制動蹄上還有多少材料。當摩擦材料磨損到鉚釘?shù)?/32英寸（0.8毫米）時，制動蹄就應該更換了。要是摩擦材料粘接到支承底板上（無鉚釘）時，當耐磨材料只剩下1/16英寸（1.6毫米）時，制動蹄就該更換了。和盤式制動器一樣，深些的劃痕有時也會損壞制動鼓。如果產(chǎn)生磨損的制動蹄仍被長時間使用的話，連接耐磨材料和襯背的鉚釘會透過槽進入制動鼓中。有劃傷的制動鼓有的可以通過返工修光處理被修復。鼓式制動器有個最大允許直徑，而盤式制動器有個最小允許厚度。由于接觸表面是制動鼓的內(nèi)表面，當鼓式制動器材料磨損時，直徑就會變大。盤式制動器的主要組成部分是：1剎車片2卡鉗，其中包含一個活塞3轉(zhuǎn)子，安裝在輪轂上盤式制動器的部件盤式制動器和自行車上的制動器很像。自行車制動器有一個卡鉗，它壓緊固聯(lián)車輪上的剎車片。在盤式制動器中，剎車片壓緊轉(zhuǎn)子而不是車輪，并且力是通過液壓傳遞地而不是通過線纜。剎車片和制動盤之間的摩擦使得制動盤減速。行駛中的汽車具有一定的動能，制動器要想使車輛停下就必須從車上移除這些能量。制動器是如何做到這點的呢？每次停車時，制動器都會將動能轉(zhuǎn)化成襯片和制動盤之間摩擦產(chǎn)生的熱能。大多數(shù)汽車盤式制動器是通風盤式。盤式制動器通風孔通風盤制動器在制動盤的兩側(cè)有一組葉片，將空氣泵過制動盤以提供冷卻。自動調(diào)整制動器單活塞浮動鉗盤式制動器有自動定心和自動調(diào)整功能?？ㄣQ能夠從一側(cè)滑到另一側(cè)，以致每次施加制動時，他都將移動到中心處。另外，由于沒有彈簧將襯片拉離制動盤，襯片始終和轉(zhuǎn)子保持輕微接觸（事實上，橡膠活塞密封圈和轉(zhuǎn)子的任何搖晃都可能將襯片從轉(zhuǎn)子上拉離一小段距離）。這點很重要，因為制動器中的活塞直徑比主缸活塞直徑大得多。如果活塞縮回制動器主缸，它將可能需要多次踩下制動踏板，向制動輪缸泵入足夠的液體，以使制動襯片壓緊。老式汽車有雙重或四個活塞固定卡鉗設計。轉(zhuǎn)子每一側(cè)有一個活塞（或兩個）壓緊制動襯片。這種設計已經(jīng)基本淘汰，因為單缸活塞設計更便宜也更可靠。應急制動四輪全采用全盤式制動器的汽車中，應急制動器必須由獨立的機械裝置驅(qū)動，以防止主制動器失效時，整個制動器都失效。大多數(shù)汽車用纜繩來驅(qū)動應急制動器。盤式制動器駐車制動有些四輪全盤式制動器的汽車，在后輪輪轂上有一個獨立的集成鼓式制動器。這個鼓式制動器只用于應急制動系統(tǒng)，僅由纜繩驅(qū)動；沒有液壓系統(tǒng)參與。其他汽車有個杠桿轉(zhuǎn)動螺桿，或驅(qū)動一個凸輪，來壓緊盤式制動器中的活塞。動力制動器是如何工作的如果你曾打開過汽車的引擎蓋，你可能已經(jīng)看到了制動助力器。它是個圓的，黑色儲罐，安置在汽車發(fā)動機艙的后部，駕駛員的一側(cè)。早先，當大部分汽車還是鼓式制動器時，動力制動器還不是真的有必要。鼓式制動器本身就能夠起到一些助力作用。現(xiàn)在因為大部分汽車都采用了盤式制動器，至少前輪都是盤式的，他們就需要動力制動器。要不是有這種裝置，許多駕駛員駕駛起來，腿部會很累。制動助力器利用發(fā)動機提供的真空來放大你的腳施加在制動主缸上的力。真空助力器真空助力器是一個有著自動閥和隔膜的金屬罐。一根穿過小罐中心的桿一側(cè)連著制動缸活塞，一側(cè)連著制動踏板。動力制動器中另一個重要的部件是單向閥。Braking SystemsDrum brakeA drum brake is a brake in which the friction is caused by a set of shoes or pads that press against the inner surface of a rotating drum. The drum is connected to a rotating wheel. Servo design Drum brakes, depending on the way the shoes are hinged, can have a self-servo characteristic. This increases stopping power without any additional effort by the driver because the rotation of the drum drags the shoes around with it, increasing the force holding them together. In rear brakes only one shoe will have this characteristic. Front drum brakes may use two actuating cylinders which allow both shoes to utilize the servo characteristic and which also increase the front axle braking force, required to compensate for forward weight shift and also to avoid premature rear wheel locking. Servo action can be used to make a very powerful brake (as on the rear axles of large commercial vehicles), but it does reduce the ability of the driver to modulate the brakes sensitively. (The disc brake has no self-servo effect because the pads act perpendicularly to the rotating disc.) Advantages Drum brakes are still used in modern cars. There can be engineering and cost advantages. Drum brakes allow simple incorporation of a parking brake. They are often applied to the rear wheels since most of the stopping happens in the front of the vehicle and therefore the heat generated in the rear is significantly less. Drum brakes are also occasionally fitted as the parking (and emergency) brake even when the rear wheels used disk brakes as the main brakes. In this situation, a small drum is usually fitted within or as part of the brake disk. An advanced technology hybrid car using drum rear brakes is the Toyota Prius. (4-wheel discs are used in certain markets - Hybrid vehicles greatly reduce everyday wear on braking systems owing to their energy recovery motor-generators, see regenerative braking). Disadvantages Drum brakes with internal shoes have a particular disadvantage; when the drums are heated by hard braking the diameter of the drum increases due to the expansion of the material and the brakes must be further depressed to obtain effective braking action. This is known as brake fade and can lead to driver panic and brake failure in extreme circumstances. Under normal driving conditions it is seldom noticed, especially when drums of appropriate size are fitted. The Pontiac GTO is one vehicle often cited as having undersized drums.Brake pads The brake pads are designed for high friction with brake pad material embedded in the disc in the process of bedding while wearing evenly. Although it is commonly thought that the pad material contacts the metal of the disc to stop the car, the pads work with a very thin layer of their own material and generate a semi-liquid friction boundary that creates the actual braking force. Of course, depending on the properties of the material, disc wear could be faster or slower than with other pads. The properties that determine material wear involve trade-offs between performance and longevity.The brake pads must be replaced regularly, and most are equipped with a method of alerting the driver when this needs to take place. Some have a thin piece of soft metal that causes the brakes to squeal when the pads are too thin, while others have a soft metal tab embedded in the pad material that closes an electric circuit and lights a warning light when the brake pad gets thin. More expensive cars may use an electronic sensor. Although almost all road-going vehicles have only two brake pads per caliper, racing calipers utilise up to six pads, with varying frictional properties in a staggered pattern for optimum performance. Early brake pads (and shoes) contained asbestos. When working on an older cars brakes, care must be taken not to inhale any dust present on the caliper (or drum).Brake squeal Sometimes a loud noise or high pitch squeal occurs when the brakes are applied. Most brake squeal is produced due to vibration (resonance instability)of the brake components especially the pads and discs. This type of squeal does not negatively affect brake stopping performance. Some simple techniques like adding chamfers to linings, greasing or gluing the contact between caliper and the pads (finger to backplate, piston to backplate), bonding insulators (damping material) to pad backplate, etc might help reduce squeal. Many times cold weather combined with high early morning humidity (dew) could make the brake squeal worse and vanishes when the lining reaches regular operating temperatures. However, some lining wear indicators are also designed to squeal when the lining is due for replacement. Overall brake squeal can be annoying to the vehicle passengers, passerby, pedestrians, etc especially as vehicles are designed to be more comfortable and quieter. Hence vehicle NVH (Noise, Vibration and Harshness) is one of the important priorities for todays vehicle manufacturers. An age-old trick is to put a small amount of copper slip (copper grease) onto the back of the pads where they contact the brake caliper piston and on the pad shims, if present. While this will normally stop the squeal, getting grease on the pads or disks will affect braking performance. Dust on the brakes may also cause squeal; there are many commercial brake cleaning products that can be used to remove dust and contaminants from the brakes. Some high-performance brake pads, such as Hawk Performance pads, will always squeal during operation, and this does not indicate a problem. Apart from noise generated from squeal, brakes may also develop a phenomenon called brake judder or shudder.Brake Dust When braking force is applied, small amounts of material are gradually ground off the brake pads. This material is known as brake dust and usually deposits itself on the braking system and the surrounding wheel. Brake dust can badly damage the finish of most wheels if not washed off. Different brake pad formulations create different amounts of dust, and some formulations are much more damaging than others.We all know that pushing down on the brake pedals lows a car to a stop. But how does this happen? How does your car transmit the force from your leg to its wheels? How does it multiply the force so that it is enough to stop something as big as a car? Layout of typical brake systemWhen you depress your brake pedal, your car transmits the force from your foot to its brakes through a fluid. Since the actual brakes require a much greater force than you could apply with your leg, your car must also multiply the force of your foot. It does this in two ways: 1 Mechanical advantage(leverage) 2 Hydraulic force multiplicationThe brakes transmit the force to the tires using friction, and the tires transmit that force to the road using friction also. Before we begin our discussion on the components of the brake system, well cover these three principles: 1 Leverage 2 Hydraulics 3 FrictionDrum brakes work on the same principle as disc brakes: Shoes press against a spinning surface. In this system, that surface is called a drum.Many cars have drum brakes on the rear wheels and disc brakes on the front. Drum brakes have more parts than disc brakes and are harder to service, but they are less expensive to manufacture, and they easily incorporate an emergency brake mechanism. In this edition of How Stuff Works, we will learn exactly how a drum brake system works, examine the emergency brake setup and find out what kind of servicing drum brakes need.The drum brake may look complicated, and it can be pretty intimidating when you open one up. Lets break it down and explain what each piece does. Like the disc brake, the drum brake has two brake shoes and a piston. But the drum brake also has an adjuster mechanism, an emergency brake mechanism and lots of springs. When you hit the brake pedal, the piston pushes the brake shoes against the drum. As the brake shoes contact the drum, there is a kind of wedging action, which has the effect of pressing the shoes into the drum with more force. The extra braking force provided by the wedging action allows drum brakes to use a smaller piston than disc brakes. But, because of the wedging action the shoes must be pulled away from the drum when the brakes are released. This is the reason for some of the springs. Other springs help hold the brake shoes in place and return the adjuster arm after it actuates.Brake Adjuster For the drum brakes to function correctly, the brake shoes must remain close to the drum without touching it. If they get too far away from the drum (as the shoes wear down, for instance), the piston will require more fluid to travel that distance, and your brake pedal will sink closer to the floor when you apply the brakes. This is why most drum brakes have an automatic adjuster. As the pad wears down, more space will form between the shoe and the drum. Each time the car stops while in reverse, the shoe is pulled tight against the drum. When the gap gets big enough, the adjusting lever rocks enough to advance the adjuster gear by one tooth. The adjuster has threads on it, like a bolt, so that it unscrews a little bit when it turns, lengthening to fill in the gap. When the brake shoes wear a little more, the adjuster can advance again, so it always keeps the shoes close to the drum. Some cars have an adjuster that is actuated when the emergency brake is applied. This type of adjuster can come out of adjustment if the emergency brake is not used for long periods of time. So if you have this type of adjuster, you should apply your emergency brake at least once a week.Servicing The most common service required for drum brakes is changing the brake shoes. Some drum brakes provide an inspection hole on the back side, where you can see how much material is left on the shoe. Brake shoes should be replaced when the friction material has worn down to within 1/32 inch (0.8 mm) of the rivets. If the friction material is bonded to the backing plate (no rivets), then the shoes should be replaced when they have only 1/16 inch (1.6 mm) of material left. Just as in disc brakes, deep scores sometimes get worn into brake drums. If a worn-out brake shoe is used for too long, the rivets that hold the friction material to the backing can wear grooves into the drum. A badly scored drum can sometimes be repaired by refinishing. Where disc brakes have a minimum allowable thickness, drum brakes have a maximum allowable diameter. Since the contact surface is the inside of the drum, as you remove material from the drum brake the diameter gets bigger. The main components of a disc brake are: 1 The brake pads2 The caliper, which contains a piston 3 The rotor, which is mounted to the hub Parts of a disc brakeThe disc brake is a lot like the brakes on a bicycle. Bicycle brakes have a caliper, which squeezes the brake pads against the wheel. In a disc brake, the brake pads squeeze the rotor instead of the wheel, and the force is transmitted hydraulically instead of through a cable. Friction between the pads and the disc slows the disc down.A moving car has a certain amount of kinetic energy and the brakes have to remove this energy from the car in order to stop it. How do the brakes do this? Each time you stop your car, your brakes convert the kinetic energy to heat generated by the friction between the pads and the disc. Most car disc brakes are vented.Disc brake ventsVented disc brakes have a set of vanes, between the two sides of the disc that pumps air through the disc to provide cooling. Self-Adjusting Brakes The single-piston floating-caliper disc brake is self-centering and self-adjusting. The caliper is able to slide from side to side so it will move to the center each time the brakes are applied. Also, since there is no spring to pull the pads away from the disc, the pads always stay in light contact with the rotor (the rubber piston seal and any wobble in the rotor may actually pull the pads a small distance away from the rotor). This is important because the pistons in the brakes are much larger in diameter than the ones in the master cylinder. If the brake pistons retracted into their cylinders, it might take several applications of the brake pedal to pum