盤(pán)式制動(dòng)器 外文翻譯
Automobile Brake System
The braking system is the most important system in cars. If the brakes fail, the result can be disastrous. Brakes are actually energy conversion devices, which convert the kinetic energy (momentum) of the vehicle into thermal energy (heat).When stepping on the brakes, the driver commands a stopping force ten times as powerful as the force that puts the car in motion. The braking system can exert thousands of pounds of pressure on each of the four brakes.
Two complete independent braking systems are used on the car. They are the service brake and the parking brake.
The service brake acts to slow, stop, or hold the vehicle during normal driving. They are foot-operated by the driver depressing and releasing the brake pedal. The primary purpose of the brake is to hold the vehicle stationary while it is unattended. The parking brake is mechanically operated by when a separate parking brake foot pedal or hand lever is set.
The brake system is composed of the following basic components: the “master cylinder” which is located under the hood, and is directly connected to the brake pedal, converts driver foot’s mechanical pressure into hydraulic pressure. Steel “brake lines” and flexible “brake hoses” connect the master cylinder to the “slave cylinders” located at each wheel. Brake fluid, specially designed to work in extreme conditions, fills the system. “Shoes” and “pads” are pushed by the slave cylinders to contact the “drums” and “rotors” thus causing drag, which (hopefully) slows the car.
The typical brake system consists of disk brakes in front and either disk or drum brakes in the rear connected by a system of tubes and hoses that link the brake at each wheel to the master cylinder (Figure).
Basically, all car brakes are friction brakes. When the driver applies the brake, the control device forces brake shoes, or pads, against the rotating brake drum or disks at wheel. Friction between the shoes or pads and the drums or disks then slows or stops the wheel so that the car is braked.
In most modern brake systems (see Figure 15.1), there is a fluid-filled cylinder, called master cylinder, which contains two separate sections, there is a piston in each section and both pistons are connected to a brake pedal in the driver’s compartment. When the brake is pushed down, brake fluid is sent from the master cylinder to the wheels. At the wheels, the fluid pushes shoes, or pads, against revolving drums or disks. The friction between the stationary shoes, or pads, and the revolving drums or disks slows and stops them. This slows or stops the revolving wheels, which, in turn, slow or stop the car.
The brake fluid reservoir is on top of the master cylinder. Most cars today have a transparent r reservoir so that you can see the level without opening the cover. The brake fluid level will drop slightly as the brake pads wear. This is a normal condition and no cause for concern. If the level drops noticeably over a short period of time or goes down to about two thirds full, have your brakes checked as soon as possible. Keep the reservoir covered except for the amount of time you need to fill it and never leave a cam of brake fluid uncovered. Brake fluid must maintain a very high boiling point. Exposure to air will cause the fluid to absorb moisture which will lower that boiling point.
The brake fluid travels from the master cylinder to the wheels through a series of steel tubes and reinforced rubber hoses. Rubber hoses are only used in places that require flexibility, such as at the front wheels, which move up and down as well as steer. The rest of the system uses non-corrosive seamless steel tubing with special fittings at all attachment points. If a steel line requires a repair, the best procedure is to replace the compete line. If this is not practical, a line can be repaired using special splice fittings that are made for brake system repair. You must never use copper tubing to repair a brake system. They are dangerous and illegal.
Drum brakes, it consists of the brake drum, an expander, pull back springs, a stationary back plate, two shoes with friction linings, and anchor pins. The stationary back plate is secured to the flange of the axle housing or to the steering knuckle. The brake drum is mounted on the wheel hub. There is a clearance between the inner surface of the drum and the shoe lining. To apply brakes, the driver pushes pedal, the expander expands the shoes and presses them to the drum. Friction between the brake drum and the friction linings brakes the wheels and the vehicle stops. To release brakes, the driver release the pedal, the pull back spring retracts the shoes thus permitting free rotation of the wheels.
Disk brakes, it has a metal disk instead of a drum. A flat shoe, or disk-brake pad, is located on each side of the disk. The shoes squeeze the rotating disk to stop the car. Fluid from the master cylinder forces the pistons to move in, toward the disk. This action pushes the friction pads tightly against the disk. The friction between the shoes and disk slows and stops it. This provides the braking action. Pistons are made of either plastic or metal. There are three general types of disk brakes. They are the floating-caliper type, the fixed-caliper type, and the sliding-caliper type. Floating-caliper and sliding-caliper disk brakes use a single piston. Fixed-caliper disk brakes have either two or four pistons.
The brake system assemblies are actuated by mechanical, hydraulic or pneumatic devices. The mechanical leverage is used in the parking brakes fitted in all automobile. When the brake pedal is depressed, the rod pushes the piston of brake master cylinder which presses the fluid. The fluid flows through the pipelines to the power brake unit and then to the wheel cylinder. The fluid pressure expands the cylinder pistons thus pressing the shoes to the drum or disk. If the pedal is released, the piston returns to the initial position, the pull back springs retract the shoes, the fluid is forced back to the master cylinder and braking ceases.
The primary purpose of the parking brake is to hold the vehicle stationary while it is unattended. The parking brake is mechanically operated by the driver when a separate parking braking hand lever is set. The hand brake is normally used when the car has already stopped. A lever is pulled and the rear brakes are approached and locked in the “on” position. The car may now be left without fear of its rolling away. When the driver wants to move the car again, he must press a button before the lever can be released. The hand brake must also be able to stop the car in the event of the foot brake failing. For this reason, it is separate from the foot brake uses cable or rods instead of the hydraulic system.
Anti-lock Brake System
Anti-lock brake systems make braking safer and more convenient, Anti-lock brake systems modulate brake system hydraulic pressure to prevent the brakes from locking and the tires from skidding on slippery pavement or during a panic stop.
Anti-lock brake systems have been used on aircraft for years, and some domestic car were offered with an early form of anti-lock braking in late 1990’s. Recently, several automakers have introduced more sophisticated anti-lock system. Investigations in Europe, where anti-lock braking systems have been available for a decade, have led one manufacture to state that the number of traffic accidents could be reduced by seven and a half percent if all cars had anti-lock brakes. So some sources predict that all cars will offer anti-lock brakes to improve the safety of the car.
Anti-lock systems modulate brake application force several times per second to hold the tires at a controlled amount of slip; all systems accomplish this in basically the same way. One or more speed sensors generate alternating current signal whose frequency increases with the wheel rotational speed. An electronic control unit continuously monitors these signals and if the frequency of a signal drops too rapidly indicating that a wheel is about to lock, the control unit instructs a modulating device to reduce hydraulic pressure to the brake at the affected wheel. When sensor signals indicate the wheel is again rotating normally, the control unit allows increased hydraulic pressure to the brake. This release-apply cycle occurs several time per second to “pump” the brakes like a driver might but at a much faster rate.
In addition to their basic operation, anti-lock systems have two other things in common. First, they do not operate until the brakes are applied with enough force to lock or nearly lock a wheel. At all other times, the system stands ready to function but does not interfere with normal braking. Second, if the anti-lock system fail in any way, the brakes continue to operate without anti-lock capability. A warning light on the instrument panel alerts the driver when a problem exists in the anti-lock system.
The current Bosch component Anti-lock Braking System (ABSⅡ), is a second generation design wildly used by European automakers such as BWM, Mercedes-Benz and Porsche. ABSⅡ system consists of : four wheel speed sensor, electronic control unit and modulator assembly.
A speed sensor is fitted at each wheel sends signals about wheel rotation to control unit. Each speed sensor consists of a sensor unit and a gear wheel. The front sensor mounts to the steering knuckle and its gear wheel is pressed onto the stub axle that rotates with the wheel. The rear sensor mounts the rear suspension member and its gear wheel is pressed onto the axle. The sensor itself is a winding with a magnetic core. The core creates a magnetic field around the winding, and as the teeth of the gear wheel move through this field, an alternating current is induced in the winding. The control unit monitors the rate o change in this frequency to determine impending brake lockup.
The control unit’s function can be divided into three parts: signal processing, logic and safety circuitry. The signal processing section is the converter that receives the alternating current signals form the speed sensors and converts them into digital form for the logic section. The logic section then analyzes the digitized signals to calculate any brake pressure changes needed. If impending lockup is sensed, the logic section sends commands to the
Modulator assembly
The hydraulic modulator assembly regulates pressure to the wheel brakes when it receives commands from the control utuit. The modulator assembly can maintain or reduce pressure over the level it receives from the master cylinder, it also can never apply the brakes by itself. The modulator assembly consists of three high-speed electric solenoid valves, two fluid reservoirs and a turn delivery pump equipped with inlet and outlet check valves. The modulator electrical connector and controlling relays are concealed under a plastic cover of the assembly.
Each front wheel is served by electric solenoid valve modulated independently by the control unit. The rear brakes are served by a single solenoid valve and modulated together using the select-low principle. During anti-braking system operation, the control unit cycles the solenoid valves to either hold or release pressure the brake lines. When pressure is released from the brake lines during anti-braking operation, it is routed to a fluid reservoir. There is one reservoir for the front brake circuit. The reservoirs are low-pressure accumulators that store fluid under slight spring pressure until the return delivery pump can return the fluid through the brake lines to the master cylinder.
譯 文：
汽車(chē)制動(dòng)系統(tǒng)
制動(dòng)系統(tǒng)是汽車(chē)重要的系統(tǒng)組成。 如果制動(dòng)失靈，結(jié)果損失可能是非常慘重的。制動(dòng)器實(shí)際就是能量轉(zhuǎn)換裝置，它將汽車(chē)的動(dòng)能（動(dòng)量）轉(zhuǎn)化成熱能（熱量）。當(dāng)駕駛員踩下制動(dòng)踏板，所產(chǎn)生的制動(dòng)力能達(dá)到汽車(chē)運(yùn)動(dòng)時(shí)動(dòng)力的10倍。制動(dòng)系統(tǒng)能對(duì)轎車(chē)四個(gè)車(chē)輪中的每個(gè)車(chē)輪施加數(shù)千磅的制動(dòng)力。
每輛汽車(chē)上使用兩個(gè)完全獨(dú)立的制動(dòng)系統(tǒng)，即行車(chē)制動(dòng)器和駐車(chē)制動(dòng)器。
行車(chē)制動(dòng)器起到減速、停車(chē)、或保持車(chē)輛正常行駛。制動(dòng)器是由司機(jī)用腳踩、松制動(dòng)器踏板來(lái)控制的。駐車(chē)制動(dòng)器的主要作用就是當(dāng)車(chē)內(nèi)無(wú)人的時(shí)候，汽車(chē)能夠保持靜止。當(dāng)獨(dú)立的駐車(chē)制動(dòng)器—踏板或手桿，被安裝時(shí)，駐車(chē)制動(dòng)器就會(huì)被機(jī)械地操作。
制動(dòng)系統(tǒng)是由下列基本的成分組成:位于發(fā)動(dòng)機(jī)罩下方，而且直接地被連接到制動(dòng)踏板的“制動(dòng)主缸”把駕駛員腳的機(jī)械力轉(zhuǎn)變?yōu)橐簤毫?。鋼制的“制?dòng)管路”和有柔性的“制動(dòng)軟管”把制動(dòng)主缸連接到每個(gè)輪子的“制動(dòng)輪缸”上。 制動(dòng)液, 特別地設(shè)計(jì)為的是工作在極端的情況，填充在系統(tǒng)中。“制動(dòng)盤(pán)”和“襯塊”是被制動(dòng)輪缸推動(dòng)接觸“圓盤(pán)”和“回轉(zhuǎn)體”如此引起緩慢的拖拉運(yùn)動(dòng), (希望)使汽車(chē)減慢速度。
典型的制動(dòng)系統(tǒng)布置有前后盤(pán)式，前盤(pán)后鼓式，各個(gè)車(chē)輪上的制動(dòng)器通過(guò)一套管路系統(tǒng)連接到制動(dòng)主缸上。
基本上講，所有的汽車(chē)制動(dòng)器都是摩擦制動(dòng)器。當(dāng)司機(jī)剎車(chē)時(shí)，控制裝置會(huì)迫使制動(dòng)蹄，或制動(dòng)襯片與車(chē)輪處的旋轉(zhuǎn)的制動(dòng)鼓或制動(dòng)盤(pán)接觸。接觸后產(chǎn)生的摩擦使車(chē)輪轉(zhuǎn)動(dòng)減慢或停止，這就是汽車(chē)的制動(dòng)。
在最基本的制動(dòng)系統(tǒng)中，有一個(gè)制動(dòng)主缸，這個(gè)主缸內(nèi)部填充制動(dòng)液，并包含兩個(gè)部分，每個(gè)部分里都有一個(gè)活塞，兩個(gè)活塞都連接駕駛室里的制動(dòng)踏板。當(dāng)制動(dòng)踏板被踩下時(shí)，制動(dòng)液會(huì)從制動(dòng)主缸流入輪缸。在輪缸中，制動(dòng)液推動(dòng)制動(dòng)蹄或制動(dòng)襯片與旋轉(zhuǎn)的制動(dòng)鼓或制動(dòng)盤(pán)接觸。靜止的制動(dòng)蹄或制動(dòng)襯片與旋轉(zhuǎn)的制動(dòng)鼓或制動(dòng)盤(pán)之間產(chǎn)生摩擦力使汽車(chē)的運(yùn)動(dòng)逐漸減緩或停止。
制動(dòng)液的裝置位于主缸的頂部。目前大多數(shù)的車(chē)都有一個(gè)容易看見(jiàn)的裝制動(dòng)液的裝置，為的是不用打開(kāi)蓋子就可以看得見(jiàn)制動(dòng)液的油面。隨著制動(dòng)踏板的運(yùn)動(dòng)制動(dòng)液就會(huì)緩慢的下降，正常情況下是這樣的。如果制動(dòng)液在很短的時(shí)間內(nèi)下降得明顯或者下降了三分之二，那么就要盡快的檢查你的制動(dòng)系統(tǒng)了。保持制動(dòng)液裝置充滿(mǎn)制動(dòng)液除非你需要維修它，制動(dòng)液必須保持很高的沸點(diǎn)。位于在空氣中的制動(dòng)液就會(huì)吸收空氣中的潮氣引起制動(dòng)液低于沸點(diǎn)。
制動(dòng)液通過(guò)一系列的管路從主缸到達(dá)各車(chē)輪。橡膠軟管只用在需要彈力的地方，比如應(yīng)用在前輪。在車(chē)的行進(jìn)中上下來(lái)回運(yùn)動(dòng)。系統(tǒng)的其它部分在所有的連接點(diǎn)上都應(yīng)用了無(wú)腐蝕性的無(wú)縫鋼管。如果鋼線(xiàn)需要修理的話(huà)，最好的方法就是代替這條線(xiàn)。如果這不符合實(shí)際，那么為了制動(dòng)系統(tǒng)可以用特殊的裝置修理它。你不可以用銅管來(lái)修理制動(dòng)系。它們是危險(xiǎn)也是不正確的。
鼓式制動(dòng)器包括制動(dòng)鼓，一個(gè)輪缸，回拉彈簧，一個(gè)制動(dòng)底版，兩個(gè)帶摩擦層的制動(dòng)蹄。制動(dòng)底版固定在輪軸外部的法蘭或轉(zhuǎn)向節(jié)。制動(dòng)鼓固定在輪轂上。制動(dòng)鼓的內(nèi)部表面與制動(dòng)蹄的內(nèi)層之間有空隙。要使用制動(dòng)器時(shí)，司機(jī)就要踩下踏板，這時(shí)輪缸擴(kuò)大制動(dòng)片，對(duì)其施加壓力，是制動(dòng)蹄觸碰制動(dòng)鼓。制動(dòng)鼓與摩擦片之間產(chǎn)生的摩擦制動(dòng)了車(chē)輪，從而使汽車(chē)停止。要釋放制動(dòng)器時(shí)，司機(jī)松開(kāi)踏板，回拉彈簧拉回制動(dòng)片，這樣車(chē)輪會(huì)自由轉(zhuǎn)動(dòng)。
盤(pán)式制動(dòng)器包括制動(dòng)盤(pán)而不是鼓，在它的兩面上各有一個(gè)薄的制動(dòng)片或叫盤(pán)式制動(dòng)器的制動(dòng)片。制動(dòng)片是靠擠住旋轉(zhuǎn)的制動(dòng)盤(pán)來(lái)停住汽車(chē)。制動(dòng)主缸里流出的制動(dòng)液迫使活塞向里部的金屬盤(pán)移動(dòng)，這便使摩擦片緊緊地貼住制動(dòng)盤(pán)。這時(shí)制動(dòng)片與制動(dòng)盤(pán)產(chǎn)生的摩擦使汽車(chē)減速、停止，出現(xiàn)了制動(dòng)行為。活塞分金屬或塑料。盤(pán)式制動(dòng)器主要有三種，即：浮動(dòng)卡鉗型、固定卡鉗型和滑動(dòng)卡鉗型。浮動(dòng)卡鉗型和滑動(dòng)卡鉗型盤(pán)式制動(dòng)器使用單活塞。固定卡鉗型盤(pán)式制動(dòng)器既可以使用兩個(gè)活塞有可以使用四個(gè)活塞。
制動(dòng)系統(tǒng)是由機(jī)械能，液壓能或氣壓能裝置驅(qū)動(dòng)的。在機(jī)械杠桿適合所有的汽車(chē)的駐車(chē)制動(dòng)器中使用。當(dāng)踩下制動(dòng)踏板時(shí)，杠桿就會(huì)推動(dòng)制動(dòng)器主缸的活塞給制動(dòng)液施加壓力，制動(dòng)液通過(guò)油管流入輪缸。制動(dòng)液的壓力施加到輪缸活塞以使制動(dòng)片被壓到制動(dòng)鼓或制動(dòng)盤(pán)上。如果松開(kāi)踏板，活塞回到原來(lái)的位置上，回拉彈簧拉回制動(dòng)片，制動(dòng)液返回制動(dòng)主缸，這樣制動(dòng)停止。
駐動(dòng)制動(dòng)器的主要作用是車(chē)內(nèi)無(wú)人時(shí)，使汽車(chē)靜止不動(dòng)。如果車(chē)內(nèi)安裝的是獨(dú)立的駐車(chē)制動(dòng)器，那么駐車(chē)制動(dòng)器是由司機(jī)手動(dòng)的控制。駐車(chē)制動(dòng)器正常是當(dāng)車(chē)已經(jīng)停止時(shí)使用的。向后拉手閘，并把手柄卡在正確的位置上。現(xiàn)在，即使離開(kāi)汽車(chē)也不用害怕它會(huì)自己滑走。如果司機(jī)要再次啟車(chē)時(shí)，他必須在松開(kāi)手桿之前按下按鈕。在行車(chē)制動(dòng)器失靈的情況下，手閘必須能停住車(chē)。正因?yàn)檫@樣，手閘與腳閘分開(kāi)，手閘使用的是繩索或杠桿而不是液力系統(tǒng)。
防抱死制動(dòng)系統(tǒng)是使汽車(chē)制動(dòng)更安全、更方便的制動(dòng)裝置，它既有調(diào)節(jié)制動(dòng)系統(tǒng)的壓力來(lái)防止車(chē)輪被完全抱死的功能，又有防止輪胎在滑的路面上行駛或緊急停車(chē)時(shí)的滑動(dòng)。
防抱死制動(dòng)系統(tǒng)最早應(yīng)用在航空飛行器上，而且在二十世紀(jì) 90年代一些國(guó)內(nèi)的汽車(chē)內(nèi)也安裝了這種系統(tǒng)。近來(lái)，幾個(gè)汽車(chē)制造商引進(jìn)了更為復(fù)雜的防抱死系統(tǒng)。歐洲使用這種系統(tǒng)已有幾十年的時(shí)間，通過(guò)對(duì)其的調(diào)查，一位汽車(chē)制造商坦言，如果所有的汽車(chē)都安裝上防抱死制動(dòng)系統(tǒng)，那么交通事故的發(fā)生率會(huì)降低7.5%。同時(shí)，一些權(quán)威人士預(yù)測(cè)這種系統(tǒng)會(huì)提高汽車(chē)的安全性。
防抱死制動(dòng)系統(tǒng)可以在一秒鐘內(nèi)調(diào)節(jié)幾次制動(dòng)時(shí)車(chē)輪上的受力，使車(chē)輪的滑移受到控制，而且所有的系統(tǒng)基本上都以相同的方式完成。每個(gè)車(chē)輪都會(huì)有一個(gè)傳感器，電子控制裝置能連續(xù)檢測(cè)來(lái)自車(chē)輪傳感器傳來(lái)的脈沖電信號(hào)，并將它們處理轉(zhuǎn)換成和輪速成正比的數(shù)值；如果其中一個(gè)傳感器的信號(hào)不斷下降，那么這就表明了相應(yīng)的輪胎趨于抱死，這時(shí)電子控制裝置向該車(chē)輪的制動(dòng)器發(fā)出降低壓力的指令。當(dāng)信號(hào)顯示車(chē)輪轉(zhuǎn)速恢復(fù)正常時(shí)，電子控制裝置會(huì)增加制動(dòng)器的液壓。這種循環(huán)像司機(jī)一樣調(diào)節(jié)制動(dòng)器，但它的速度更快，達(dá)到了每秒循環(huán)數(shù)次。
防抱死制動(dòng)系統(tǒng)除了上面基本操作，還有兩個(gè)特點(diǎn)。首先，當(dāng)制動(dòng)系統(tǒng)的壓力上升到使輪胎抱死或即將抱死的時(shí)候，防抱死制動(dòng)系統(tǒng)才會(huì)啟動(dòng)；當(dāng)制動(dòng)系統(tǒng)在正常情況下，防抱死制動(dòng)系統(tǒng)停止運(yùn)作。其次，如果防抱死制動(dòng)系統(tǒng)有問(wèn)題時(shí)，制動(dòng)器會(huì)獨(dú)立地繼續(xù)運(yùn)行。但控制板上的指示燈亮起提醒司機(jī)系統(tǒng)出現(xiàn)問(wèn)題。
目前歐洲汽車(chē)生產(chǎn)商，如：寶馬、奔馳、寶時(shí)捷等廣泛使用的是波許（Bosch）防抱死制動(dòng)系統(tǒng)。這種系統(tǒng)基本組成包括車(chē)輪轉(zhuǎn)速傳感器，電子控制裝置和調(diào)節(jié)裝置。
每個(gè)有一個(gè)向電子控制裝置發(fā)出車(chē)輪轉(zhuǎn)動(dòng)情況的信號(hào)的傳感器，它一般由磁感應(yīng)傳感頭和齒圈組成。前面的傳感器安在輪轂上，齒圈安在輪網(wǎng)上。后面的傳感器安在后部的監(jiān)測(cè)系統(tǒng)上，齒圈安在輪軸上。傳感器本身是纏繞電磁核的電線(xiàn)圈，電磁核才線(xiàn)圈的周?chē)a(chǎn)生磁場(chǎng)。當(dāng)齒圈的齒移動(dòng)到磁場(chǎng)時(shí)，就會(huì)改變線(xiàn)圈的電流。電子控制裝置會(huì)監(jiān)測(cè)這種變化，然后判斷車(chē)輪是否即將抱死。
電子控制裝置有三個(gè)作用，即：信號(hào)的處理，編輯和安全防護(hù)。信號(hào)的處理起到轉(zhuǎn)換器的作用，它是將接受的脈沖電信號(hào)處理轉(zhuǎn)換成數(shù)值，為編輯做準(zhǔn)備。編輯就是分析這些數(shù)值，計(jì)算出需要制動(dòng)壓力。如果檢測(cè)出車(chē)輪即將抱死，電控裝置就會(huì)計(jì)算出數(shù)值向調(diào)節(jié)裝置發(fā)出指令。
調(diào)節(jié)裝置
當(dāng)接受到電子控制裝置的指令后，液壓執(zhí)行裝置會(huì)調(diào)節(jié)制動(dòng)輪缸的液壓的大小。調(diào)節(jié)裝置能保持或減小來(lái)自制動(dòng)主缸的液壓，而裝置本身是不能啟用制動(dòng)器的。這種裝置有三個(gè)高速率的電磁閥，兩個(gè)油液存儲(chǔ)器和一個(gè)帶有內(nèi)外檢測(cè)閥的傳動(dòng)泵。調(diào)節(jié)裝置中的電子連接器隱藏在塑料蓋下。
每個(gè)電磁閥都是其獨(dú)立控制的，并作用于前輪。后部的制動(dòng)輪缸受到一個(gè)電磁閥控制，并依照------的原理進(jìn)行調(diào)節(jié)。當(dāng)防抱死制動(dòng)系統(tǒng)運(yùn)行時(shí)，電子控制裝置會(huì)使電磁閥循環(huán)運(yùn)作，這樣既能收回又能釋放制動(dòng)器的壓力。當(dāng)壓力釋放時(shí)，它會(huì)釋放到液壓?jiǎn)卧Ｇ安康闹苿?dòng)器電路有一個(gè)單元。存儲(chǔ)器低壓存儲(chǔ)器，它在低壓下存儲(chǔ)油液，直到回流泵打開(kāi)，油液流經(jīng)制動(dòng)輪缸進(jìn)入制動(dòng)主缸。
1.課題研究的目的及意義
汽車(chē)的設(shè)計(jì)與生產(chǎn)涉及到許多領(lǐng)域，其獨(dú)有的安全性、經(jīng)濟(jì)性、舒適性等眾多指標(biāo)，也對(duì)設(shè)計(jì)提出了更高的要求。汽車(chē)制動(dòng)系統(tǒng)是汽車(chē)行駛的一個(gè)重要主動(dòng)安全系統(tǒng)，其性能的好壞對(duì)汽車(chē)的行駛安全有著重要影響。隨著汽車(chē)的形式速度和路面情況復(fù)雜程度的提高，更加需要高性能、長(zhǎng)壽命的制動(dòng)系統(tǒng)。其性能的好壞對(duì)汽車(chē)的行駛安全有著重要影響，如果此系統(tǒng)不能正常工作，車(chē)上的駕駛員和乘客將會(huì)受到車(chē)禍的傷害。
汽車(chē)是現(xiàn)代交通工具中用得最多、最普遍、也是運(yùn)用得最方便的交通工具。汽車(chē)制動(dòng)系統(tǒng)是汽車(chē)底盤(pán)上的一個(gè)重要系統(tǒng)，它是制約汽車(chē)運(yùn)動(dòng)的裝置，而制動(dòng)器又是制動(dòng)系中直接作用制約汽車(chē)運(yùn)動(dòng)的一個(gè)關(guān)鍵裝置，是汽車(chē)上最重要的安全件。汽車(chē)的制動(dòng)性能直接影響汽車(chē)的行駛安全性。隨著公路業(yè)的迅速發(fā)展和車(chē)流密度的日益增大，人們對(duì)安全性、可靠性的要求越來(lái)越高，為保證人身和車(chē)輛安全，必須為汽車(chē)配備十分可靠的制動(dòng)系統(tǒng)。
車(chē)輛在形式過(guò)程中要頻繁進(jìn)行制動(dòng)操作，由于制動(dòng)性能的好壞直接關(guān)系到交通和人身安全，因此制動(dòng)性能是車(chē)輛非常重要的性能之一，改善汽車(chē)的制動(dòng)性能始終是汽車(chē)設(shè)計(jì)制造和使用部門(mén)的重要任務(wù)。
現(xiàn)代汽車(chē)普遍采用的摩擦式制動(dòng)器的實(shí)際工作性能是整個(gè)制動(dòng)系中最復(fù)雜、最不穩(wěn)定的因素，因此改進(jìn)制動(dòng)器機(jī)構(gòu)、解決制約其性能的突出問(wèn)題具有非常重要的意義。
2.汽車(chē)制動(dòng)器的國(guó)內(nèi)外現(xiàn)狀及發(fā)展趨勢(shì)
對(duì)制動(dòng)器的早期研究側(cè)重于試驗(yàn)研究其摩擦特性，隨著用戶(hù)對(duì)其制動(dòng)性能和使用壽命要求的不斷提高，有關(guān)其基礎(chǔ)理論與應(yīng)用方面的研究也在深入進(jìn)行。
目前，汽車(chē)所用的制動(dòng)器幾乎都是摩擦式的，可分為鼓式和盤(pán)式兩大類(lèi)。盤(pán)式制動(dòng)器被普遍使用。但由于為了提高其制動(dòng)效能而必須加制動(dòng)增力系統(tǒng)，使其造價(jià)較高，故低端車(chē)一般還是使用前盤(pán)后鼓式。汽車(chē)制動(dòng)過(guò)程實(shí)際上是一個(gè)能量轉(zhuǎn)換過(guò)程，它把汽車(chē)行駛時(shí)產(chǎn)生的動(dòng)能轉(zhuǎn)換為熱能。高速行駛的汽車(chē)如果頻繁使用制動(dòng)器，制動(dòng)器因摩擦?xí)a(chǎn)生大量的熱量，使制動(dòng)器溫度急劇升高，如果不能及時(shí)的為制動(dòng)器散熱，它的效率就會(huì)大大降低，影響制動(dòng)性能，出現(xiàn)所謂的制動(dòng)效能熱衰退現(xiàn)象。
在中高級(jí)轎車(chē)上前后輪都已經(jīng)采用了盤(pán)式制動(dòng)器。不過(guò)，時(shí)下還有不少經(jīng)濟(jì)型轎車(chē)采用的還不完全是盤(pán)式制動(dòng)器，而是前盤(pán)后鼓式混合制動(dòng)器（即前輪采用盤(pán)式制動(dòng)器、后輪采用鼓式制動(dòng)器），這主要是出于成本上的考慮，同時(shí)也是因?yàn)檗I車(chē)在緊急制動(dòng)時(shí)，負(fù)荷前移，對(duì)前輪制動(dòng)的要求比較高，一般來(lái)說(shuō)前輪用盤(pán)式制動(dòng)器就夠了。當(dāng)然，前后輪都使用盤(pán)式制動(dòng)器是一種趨勢(shì)。在貨車(chē)上，盤(pán)式制動(dòng)器也有被采用的，但離完全取代鼓式制動(dòng)器還有相當(dāng)長(zhǎng)的一段距離。
現(xiàn)代汽車(chē)制動(dòng)器的發(fā)展起源于原始的機(jī)械控制裝置，最原始的制動(dòng)控制只是駕駛員操縱一組簡(jiǎn)單的機(jī)械裝置向制動(dòng)器施加作用力，那時(shí)的汽車(chē)重量比較小，速度比較低，機(jī)械制動(dòng)已經(jīng)能夠滿(mǎn)足汽車(chē)制動(dòng)的需要，但隨著汽車(chē)自身重量的增加，助力裝置對(duì)機(jī)械制動(dòng)器來(lái)說(shuō)越來(lái)越顯得非常重要,從而開(kāi)始出現(xiàn)了真空助力裝置。另外，近年來(lái)則出現(xiàn)了一些全新的制動(dòng)器結(jié)構(gòu)形式，如磁粉制動(dòng)器、濕式多盤(pán)制動(dòng)器、電力液壓制動(dòng)臂型盤(pán)式制動(dòng)器、濕式盤(pán)式彈簧制動(dòng)器等。
3.課題研究的內(nèi)容
制動(dòng)器是制動(dòng)系中最主要的一個(gè)部件，是制動(dòng)系統(tǒng)中用以產(chǎn)生阻礙車(chē)輛的運(yùn)動(dòng)或運(yùn)動(dòng)趨勢(shì)的力的部件。
凡是利用固定元件與旋轉(zhuǎn)元件工作表面的摩擦而產(chǎn)生制動(dòng)力矩的制動(dòng)器都稱(chēng)為摩擦制動(dòng)器，摩擦制動(dòng)器可分為鼓式和盤(pán)式兩大類(lèi)。前者的摩擦副中的旋轉(zhuǎn)元件為制動(dòng)鼓，其工作表面為圓柱面；后者的旋轉(zhuǎn)元件則為圓盤(pán)狀的制動(dòng)盤(pán)，以端面為工作表面。
目前廣泛使用的是摩擦式制動(dòng)器,盤(pán)式制動(dòng)器的摩擦力產(chǎn)生于同汽車(chē)固定部位相連的部件與一個(gè)或幾個(gè)制動(dòng)盤(pán)兩端面之間。其中摩擦材料僅能覆蓋制動(dòng)盤(pán)工作表面的一小部分的盤(pán)式制動(dòng)器稱(chēng)為鉗盤(pán)式制動(dòng)器；摩擦材料覆蓋制動(dòng)盤(pán)全部工作表面盤(pán)式制動(dòng)器稱(chēng)為全盤(pán)式制動(dòng)器?，F(xiàn)代汽車(chē)中以單盤(pán)單鉗式的鉗盤(pán)式制動(dòng)器應(yīng)用最為廣泛，僅有個(gè)別大噸位礦用自卸車(chē)采用單盤(pán)三鉗和雙盤(pán)單鉗的鉗盤(pán)式制動(dòng)器，以及全盤(pán)式制動(dòng)器。鉗盤(pán)式制動(dòng)器中定鉗盤(pán)式為制動(dòng)鉗固定在制動(dòng)盤(pán)兩側(cè)，且在其兩側(cè)均設(shè)有加壓機(jī)構(gòu)。浮鉗盤(pán)式制動(dòng)器僅在制動(dòng)盤(pán)一側(cè)設(shè)有加壓機(jī)構(gòu)的制動(dòng)鉗，借其本身的浮動(dòng)，而在制動(dòng)盤(pán)的另一側(cè)產(chǎn)生壓緊力。又分為制動(dòng)鉗可相對(duì)于制動(dòng)鉗可相對(duì)于制動(dòng)盤(pán)軸向滑動(dòng)鉗盤(pán)式制動(dòng)器；與制動(dòng)鉗可在垂直于制動(dòng)盤(pán)的平面內(nèi)擺動(dòng)的擺動(dòng)鉗盤(pán)式制動(dòng)器。
鼓式制動(dòng)器摩擦副中的旋轉(zhuǎn)元件為制動(dòng)鼓，鼓式制動(dòng)器根據(jù)其結(jié)構(gòu)都不同，又分為：雙向自增力蹄式制動(dòng)器、雙領(lǐng)蹄式制動(dòng)器、領(lǐng)從蹄式制動(dòng)器、雙從蹄式制動(dòng)器。
正如上面我們看的一樣，制動(dòng)器器的類(lèi)型很多，那么每種類(lèi)型的制動(dòng)器器都適用什么類(lèi)型的車(chē)呢？是不是有種減速器是完美無(wú)缺的？本課題就是來(lái)解決這些問(wèn)題的。其實(shí)每種類(lèi)型都有它的優(yōu)缺點(diǎn)，我們本課題要研究的內(nèi)容就是要通過(guò)分析設(shè)計(jì)，找出不同類(lèi)型的減速器的優(yōu)缺點(diǎn)。了解了他們的優(yōu)缺點(diǎn)后我們就能更好更充分的利用它們，為汽車(chē)優(yōu)化設(shè)計(jì)提供方便。
4.完成課題的實(shí)驗(yàn)條件、預(yù)計(jì)設(shè)計(jì)過(guò)程中可能遇到的問(wèn)題以及解決的方法和措施
由于對(duì)專(zhuān)業(yè)知識(shí)的不熟練，可能需要查閱眾多的資料。根據(jù)設(shè)計(jì)車(chē)型的特點(diǎn)，合理計(jì)算該車(chē)型制動(dòng)系統(tǒng)制動(dòng)力及制動(dòng)器最大制動(dòng)力矩、鼓式制動(dòng)器的結(jié)構(gòu)形式及選擇、鼓式制動(dòng)器主要參數(shù)的計(jì)算與確定、摩擦襯塊的磨損特性計(jì)算、制動(dòng)器熱容量和溫升的核算、制動(dòng)力矩的計(jì)算與校核、在二維或三維設(shè)計(jì)平臺(tái)AUTO CAD中完成鼓式制動(dòng)器零件圖以及裝配圖的繪制、設(shè)計(jì)合理性的分析和評(píng)價(jià)等。
本次設(shè)計(jì)的目的是通過(guò)合理整和已有的設(shè)計(jì)，閱讀大量文獻(xiàn)，掌握機(jī)械設(shè)計(jì)的基本步驟和要求，以及傳統(tǒng)的機(jī)械制圖的步驟和規(guī)則；掌握鼓式制動(dòng)器總成的相關(guān)設(shè)計(jì)方法，以進(jìn)一步扎實(shí)汽車(chē)設(shè)計(jì)基本知識(shí)；學(xué)會(huì)用AUTO CAD,CATIA等三維軟件進(jìn)行基本的二維或三維建模和制圖，同時(shí)提高分析問(wèn)題及解決問(wèn)題的能力。提出將各種設(shè)計(jì)方法互相結(jié)合,針對(duì)不同的設(shè)計(jì)內(nèi)容分別應(yīng)用不同的方法,以促進(jìn)其設(shè)計(jì)過(guò)程方法優(yōu)化、設(shè)計(jì)結(jié)果精益求精。
5.畢業(yè)設(shè)計(jì)實(shí)施計(jì)劃
第1-4周：查閱資料，分析課題研究的內(nèi)容，外文翻譯，寫(xiě)開(kāi)題報(bào)告；
第5-6周：比較分析各種不同類(lèi)型主減速器的優(yōu)缺
第7-8周：分析確定幾種不同類(lèi)型的主減速器，并繪制出草圖
第9-10周：具體數(shù)據(jù)計(jì)算
第11-15周：確定主減速器總裝配圖并繪制總裝配圖：
均為計(jì)算機(jī)繪圖；
第16-17周：撰寫(xiě)畢業(yè)論文，準(zhǔn)備答辯。
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