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黑龍江工程學(xué)院本科生畢業(yè)設(shè)計(jì)
附 錄A 英文文獻(xiàn)
Final drive\Differential
All vehicles have some type of drive axle/differential assembly incorporated into the driveline. Whether it is front, rear or four wheel drive, differentials are necessary for the smooth application of engine power to the road.
Powerflow
The drive axle must transmit power through a 90° angle. The flow of power in conventional front engine/rear wheel drive vehicles moves from the engine to the drive axle in approximately a straight line. However, at the drive axle, the power must be turned at right angles (from the line of the driveshaft) and directed to the drive wheels.
This is accomplished by a pinion drive gear, which turns a circular ring gear. The ring gear is attached to a differential housing, containing a set of smaller gears that are splined to the inner end of each axle shaft. As the housing is rotated, the internal differential gears turn the axle shafts, which are also attached to the drive wheels.
Fig 1 Drive axle
Rear-wheel drive
Rear-wheel-drive vehicles are mostly trucks, very large sedans and many sports car and coupe models. The typical rear wheel drive vehicle uses a front mounted engine and transmission assemblies with a driveshaft coupling the transmission to the rear drive axle. Drive in through the layout of the bridge, the bridge drive shaft arranged vertically in the same vertical plane, and not the drive axle shaft, respectively, in their own sub-actuator with a direct connection, but the actuator is located at the front or the back of the adjacent shaft
of the two bridges is arranged in series. Vehicle before and after the two ends of the driving force of the drive axle, is the sub-actuator and the transmission through the middle of the bridge. The advantage is not only a reduction of the number of drive shaft, and raise the driving axle of the common parts of each other, and to simplify the structure, reduces the volume and quality.
Fig 2 Rear-wheel-drive axle
Some vehicles do not follow this typical example. Such as the older Porsche or Volkswagen vehicles which were rear engine, rear drive. These vehicles use a rear mounted transaxle with halfshafts connected to the drive wheels. Also, some vehicles were produced with a front engine, rear transaxle setup with a driveshaft connecting the engine to the transaxle, and halfshafts linking the transaxle to the drive wheels.
Differential operation
In order to remove the wheel around in the kinematics due to the lack of co-ordination about the wheel diameter arising from a different or the same rolling radius of wheel travel required, inter-wheel motor vehicles are equipped with about differential, the latter to ensure that the car driver Bridge on both sides of the wheel when in range with a trip to the characteristics of rotating at different speeds to meet the requirements of the vehicle kinematics.
Fig 3 Principle of differential
The accompanying illustration has been provided to help understand how this occurs.
1.The drive pinion, which is turned by the driveshaft, turns the ring gear.
2.The ring gear, which is attached to the differential case, turns the case.
3.The pinion shaft, located in a bore in the differential case, is at right angles to the axle shafts and turns with the case.
4.The differential pinion (drive) gears are mounted on the pinion shaft and rotate with the shaft .
5.Differential side gears (driven gears) are meshed with the pinion gears and turn with the differential housing and ring gear as a unit.
6.The side gears are splined to the inner ends of the axle shafts and rotate the shafts as the housing turns.
7.When both wheels have equal traction, the pinion gears do not rotate on the pinion shaft, since the input force of the pinion gears is divided equally between the two side gears.
8.When it is necessary to turn a corner, the differential gearing becomes effective and allows the axle shafts to rotate at different speeds .
Open-wheel differential on each general use the same amount of torque. To determine the size of the wheel torque to bear two factors: equipment and friction. In dry conditions, when a lot of friction, the wheel bearing torque by engine size and gear restrictions are hours in the friction (such as driving on ice), is restricted to a maximum torque, so that vehicles will not spin round. So even if the car can produce more torque, but also need to have sufficient traction to transfer torque to the ground. If you increase the throttle after the wheels slip, it will only make the wheels spin faster.
Fig 4 Conventional differential
Limited-slip and locking differential operation
Fig 5 Limited-slip differential
Differential settlement of a car in the uneven road surface and steering wheel-driven speed at about the different requirements; but is followed by the existence of differential in the side car wheel skid can not be effective when the power transmission, that is, the wheel slip can not produce the driving force, rather than spin the wheel and does not have enough torque. Good non-slip differential settlement of the car wheels skid on the side of the power transmission when the issue, that is, locking differential, so that no longer serve a useful differential right and left sides of the wheel can be the same torque.
Limited-slip and locking differential operation can be divided into two major categories：
(1) mandatory locking type in ordinary differential locking enforcement agencies to increase, when the side of the wheel skid occurs, the driver can be electric, pneumatic or mechanical means to manipulate the locking body meshing sets of DIP Shell will be with the axle differential lock into one, thus the temporary loss of differential role. Relatively simple structure in this way, but it must be operated by the driver, and good roads to stop locking and restore the role of differential.
???? (2) self-locking differential installed in the oil viscosity or friction clutch coupling, when the side of the wheel skid occurs when both sides of the axle speed difference there, coupling or clutch friction resistance on the automatic, to make certain the other side of the wheel drive torque and the car continued to travel. When there is no speed difference on both sides of the wheel, the frictional resistance disappeared, the role of automatic restoration of differentials. More complicated structure in this way, but do not require drivers to operate. Has been increasingly applied in the car. About non-slip differential, not only used for the differential between the wheels, but also for all-wheel drive vehicle inter-axle differential/.
Gear ratio
The drive axle of a vehicle is said to have a certain axle ratio. This number (usually a whole number and a decimal fraction) is actually a comparison of the number of gear teeth on the ring gear and the pinion gear. For example, a 4.11 rear means that theoretically, there are 4.11 teeth on the ring gear for each tooth on the pinion gear or, put another way, the driveshaft must turn 4.11 times to turn the wheels once. The role of the final drive is to reduce the speed from the drive shaft, thereby increasing the torque. Lord of the reduction ratio reducer, a driving force for car performance and fuel economy have a greater impact. In general, the more reduction ratio the greater the acceleration and climbing ability, and relatively poor fuel economy. However, if it is too large, it can not play the full power of the engine to achieve the proper speed. The main reduction ratio is more Smaller ，the speed is higher, fuel economy is better, but the acceleration and climbing ability will be poor.
附 錄B 文獻(xiàn)翻譯
主減速器和差速器
所有的汽車都裝有不同類型的主減速器和差速器來驅(qū)動汽車行駛。無論是前驅(qū)汽車，后驅(qū)汽車還是四輪驅(qū)動的汽車，對于將發(fā)動機(jī)的動力轉(zhuǎn)化到車輪上差速器都是不可缺少的部件。
動力的傳遞
驅(qū)動橋必須把發(fā)動機(jī)的動力轉(zhuǎn)一個直角后傳遞出去，但人對于前輪驅(qū)動汽車發(fā)動機(jī)輸出的轉(zhuǎn)矩與主減速器是在同一直線上的，但是發(fā)動機(jī)前置的后輪驅(qū)動的汽車發(fā)動機(jī)的動力必須以正確的角度傳遞出去，來驅(qū)動車輪。
圖中所示是齒輪驅(qū)動的過程，即由一個相對小的齒輪驅(qū)動一個大齒輪（主動齒輪和從動齒輪），從動錐齒輪和差速器殼連接在一起，在半軸的根部有一對帶有內(nèi)花鍵的半軸齒輪，半軸齒輪和半軸通過花鍵來連接在一起。當(dāng)差速器殼旋轉(zhuǎn)時，就驅(qū)動內(nèi)部的半齒輪轉(zhuǎn)動從而使半軸轉(zhuǎn)動，將轉(zhuǎn)矩傳給車輪。
后驅(qū)動橋
后輪驅(qū)動的車輛大多是卡車，大型轎車和大部分跑車。典型的后輪驅(qū)動的車輛使用前置發(fā)動機(jī)和變速箱總成將轉(zhuǎn)矩傳輸?shù)胶筝嗱?qū)動橋。多驅(qū)動橋汽車中，在貫通式驅(qū)動橋的布置中，各橋的傳動軸布置在同一縱向鉛垂平面內(nèi)，并且各驅(qū)動橋不是分別用自己的傳動軸與分動器直接聯(lián)接，而是位于分動器前面的或后面的各相鄰兩橋的傳動軸，是串聯(lián)布置的。汽車前后兩端的驅(qū)動橋的動力，是經(jīng)分動器并貫通中間橋而傳遞的。其優(yōu)點(diǎn)是，不僅減少了傳動軸的數(shù)量，而且提高了各驅(qū)動橋零件的相互通用性，并且簡化了結(jié)構(gòu)、減小了體積和質(zhì)量。
一些車輛不是這個典型的例子。如老式的保時捷或大眾汽車引擎在汽車后面，是后輪驅(qū)動。這些車輛使用的后方安裝驅(qū)動橋與半軸來驅(qū)動車輪。另外，一些車輛是前置引擎，后橋與傳動軸連接發(fā)動機(jī)來驅(qū)動車輪。
差速器
為了消除由于左右車輪在運(yùn)動學(xué)上的不協(xié)調(diào)而產(chǎn)生左右車輪外徑不同或滾動半徑不相等而要求車輪行程，汽車左右驅(qū)動輪間都裝有差速器，后者保證了汽車驅(qū)動橋兩側(cè)車輪在行程不等時具有以不同速度旋轉(zhuǎn)的特性，從而滿足了汽車行駛運(yùn)動學(xué)要求。
如圖所示說明了其工作情況
1. 主動齒輪轉(zhuǎn)動，從而驅(qū)動從動齒輪。
2. 從動齒輪將轉(zhuǎn)矩作用于差速器殼，使其轉(zhuǎn)動。
3. 位于差速器殼中的行星齒輪以適當(dāng)?shù)慕嵌群桶胼S齒輪接觸，并隨的差速器殼轉(zhuǎn)動。
4. 行星齒輪（驅(qū)動齒輪）和十字軸連接，和十字軸一起轉(zhuǎn)動。
5. 半軸齒輪（被驅(qū)動齒輪）和行星齒輪嚙合并且和從動齒輪及差速器殼作為一個整體一起轉(zhuǎn)動。
6. 半軸齒輪的內(nèi)花鍵和半軸端部餓花鍵接在一起隨著差速殼一起轉(zhuǎn)動。
7. 當(dāng)兩側(cè)車輪轉(zhuǎn)速相同時，行星齒輪和半軸齒輪無相對運(yùn)動，左右齒輪力矩平均分配。
8. 當(dāng)汽車轉(zhuǎn)彎時差速器開始起作用，是兩側(cè)的半軸以不同的轉(zhuǎn)速旋轉(zhuǎn)。
開式差速器對每個車輪一般使用相同量的扭矩。確定車輪承受的扭矩大小的因素有兩個：設(shè)備和摩擦力。在干燥的條件下，當(dāng)摩擦力很大時，車輪承受的扭矩大小受發(fā)動機(jī)和擋位的限制，在摩擦力很小時（如在冰上行駛），限制為最大扭矩，從而使車輪不會打滑。所以，即使汽車可以產(chǎn)生較大扭矩，也需要足夠的牽引力將扭矩傳輸?shù)降孛妗Ｈ绻谲囕喆蚧蠹哟笥烷T，只會使車輪更快地旋轉(zhuǎn)。 如果曾在冰上駕駛過，您可能知道加速的竅門：如果啟動時掛在二擋或三擋而不是一擋，則由于變速器中的齒輪傳動，車輪的扭矩會較小。這樣更容易在不旋轉(zhuǎn)車輪的情況下加速。如果其中一個驅(qū)動輪具有很好的摩擦力，而另一個卻在冰上時，這是開式差速器存在的問題。
防滑差速器
差速器很好的解決了汽車在不平路面及轉(zhuǎn)向時左右驅(qū)動車輪轉(zhuǎn)速不同的要求；但隨之而來的是差速器的存在使得汽車在一側(cè)驅(qū)動輪打滑時動力無法有效傳輸，也就是打滑的車輪不能產(chǎn)生驅(qū)動力，而不打滑的車輪又沒有得到足夠的扭矩。防滑差速器很好的解決了汽車在一側(cè)車輪打滑時出現(xiàn)的動力傳輸?shù)膯栴}，也就是鎖止差速器，讓差速器不再起作用，左右兩側(cè)的驅(qū)動輪均可得到相同的扭矩。
防滑差速器主要可分為兩大類：
（1）強(qiáng)制鎖止式在普通差速器上增加強(qiáng)制鎖止機(jī)構(gòu)，當(dāng)發(fā)生一側(cè)車輪打滑時，駕駛員可通過電動、氣動或機(jī)械的方式來操縱鎖止機(jī)構(gòu)，撥動嚙合套將差速器殼與半軸鎖成一體，從而暫時失去差速的作用。這種方式結(jié)構(gòu)比較簡單，但必須由駕駛員進(jìn)行操作，并在良好路面上停止鎖止，恢復(fù)差速器的作用。
（2）自鎖式在差速器中安裝粘性硅油聯(lián)軸節(jié)或摩擦離合器，當(dāng)發(fā)生一側(cè)車輪打滑時，兩側(cè)半軸出現(xiàn)轉(zhuǎn)速差，聯(lián)軸節(jié)或離合器就自動發(fā)生摩擦阻力，使另一側(cè)車輪得到一定的扭矩而驅(qū)動汽車?yán)^續(xù)行駛。當(dāng)兩側(cè)車輪沒有轉(zhuǎn)速差時，摩擦阻力消失，自動恢復(fù)差速器的作用。這種方式結(jié)構(gòu)比較復(fù)雜，但不需要駕駛員進(jìn)行操作。目前已越來越多地在汽車上得到應(yīng)用。 防滑差速器不僅用于左右車輪間的差速器，也用于全輪驅(qū)動汽車的軸間差速器中。
主減速比
驅(qū)動橋都有一定得主減速比，這個數(shù)字（通常是一個整數(shù)和一個小數(shù)）實(shí)際上是主減速器主動齒輪與從動齒輪的關(guān)系。例如，如果主減速比為4.11則說明從動齒輪的齒數(shù)是主動齒輪齒數(shù)的4.11倍，換句話說就是主動齒輪軸轉(zhuǎn)動4圈車輪才轉(zhuǎn)動1圈。
主減速器的作用是降低從傳動軸傳來的轉(zhuǎn)速，從而增大扭矩。主減速器的減速比，對汽車的動力性能和燃料經(jīng)濟(jì)性有較大的影響。一般來說，主減速比越大，加速性能和爬坡能力較強(qiáng)，而燃料經(jīng)濟(jì)性比較差。但如果過大，則不能發(fā)揮發(fā)動機(jī)的全部功率而達(dá)到應(yīng)有的車速。主減速比越小，燃料經(jīng)濟(jì)性較好，但加速性和爬坡能力較差。
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