【正文】 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 acplished 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 Rearwheel driveRearwheeldrive 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 subactuator 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 subactuator 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 mon parts of each other, and to simplify the structure, reduces the volume and quality.Fig 2 Rearwheeldrive axleSome 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 operationIn order to remove the wheel around in the kinematics due to the lack of coordination about the wheel diameter arising from a different or the same rolling radius of wheel travel required, interwheel 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 differentialThe acpanying illustration has been provided to help understand how this occurs. drive pinion, which is turned by the driveshaft, turns the ring gear. ring gear, which is attached to the differential case, turns the case. pinion shaft, located in a bore in the differential case, is at right angles to the axle shafts and turns with the case. differential pinion (drive) gears are mounted on the pinion shaft and rotate with the shaft . side gears (driven gears) are meshed with the pinion gears and turn with the differential housing and ring gear as a unit. side gears are splined to the inner ends of the axle shafts and rotate the shafts as the housing turns. 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. it is necessary to turn a corner, the differential gearing bees effective and allows the axle shafts to rotate at different speeds .Openwheel 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 differentialLimitedslip and locking differential operation Fig 5 Limitedslip differentialDifferential settlement of a car in the uneven road surface and steering wheeldriven speed at about the different requirements。最后，向參加論文審閱、答辯的專家和老師表示感謝。再次向孫老師表示衷心的感謝！感謝汽車工程系所有老師對我孜孜不倦的教導，感謝同學生活和學習上對我的幫助。通過這次畢業(yè)設計，使我將三年半來學到的知識進行了一次大總結，一次大檢查，特別是機械設計、工程制圖、機械原理等基礎知識，進行了一次徹底的復習，并且在設計中學習了ansys軟件。另外，在某些方面，由于時間問題，做得還不夠仔細，懇請各位老師同學給予批評指正。由于結構簡單、主減速器造價低廉、工作可靠，能大大降低整車生產的總成本推動汽車經濟的發(fā)展，可以被廣泛用在各種輕型載貨汽車。利用PRO/E建模及ANSYS軟件分析驗證合理性。結 論 本次設計的輕型貨車主減速器是根據(jù)傳統(tǒng)主減速器設計方法，并結合現(xiàn)代設計方法，參考相關車型，確定了主減速器的總體設計方案。通過有限元分析可知，所設計的從動錐齒輪及選用的材料均符合要求。應力最大值為5757Pa。 總方向位移變形狀況 位移變形圖變形量分析：，可見從動錐齒輪的變形量很小，充分滿足剛度要求。 從齒輪加載 （4）查看變形結果： General PostProc/Plot Results/Plot Results/Contour Plot/Nodal Solu/DOF Solution。施加載荷操作如下：Solution/Define Loads/Apply/Structural/Force/Moment/On Nodes，由于所有的線和面在網格劃分開始時已經指定大小，生成網格的質量與待劃分網格的面或體順序無關。Smartsize算法首先對待劃分網格的面或體的所有線估算單元邊長。本設計使用的是自由網格，因為它可以通過Smartsize自己控制網格的劃分精度。 定義材料屬性定義完材料屬性后就可以對齒輪模型進行網格劃分了。在右側列表框中依次選擇StructuralLinearElasticIsotropic命令。 定義元素類型定義完元素類型后應該定義材料的屬性。依次展開Main MeunPreprocessorElement TypesAdd/Edit/Delete命令， Types的對話框。主減速器從動錐齒輪的有限元受力分析：（1）將Pro\； 從動錐齒輪（2）對模型進行定義網格類型，定義材料屬性，網格劃分； 從動錐齒輪的材料選用20CrMnTi。20CrMnTi的抗拉強度為，無論是單個方向的最大應力，還是綜合應力值均充分滿足強度要求。查看列表應力獲取最大應力：執(zhí)行Utility Menu/List/Results/Nodal Solution 命令，把各個節(jié)點的應力值以列表的形式輸出如下圖； 總方向應力狀況 應力分布圖應力結果分析：數(shù)值顯示，藍色部位應力值最小，紅色部位應力值最大。 變形如面分析下圖。： 網格化分（3）加載步驟如下:Solution/Analysis Type/New Analysis/Static；Solution/Define Loads/Apply/Structural/Displacement/On Areas；選擇主動錐齒輪的兩個端面進行約束，這里有ALL DOF(全約束)、UX（X方向位移）、UY（Y方向位移）、UZ（Z方向位移）、ROTX（X方向旋轉）、ROTY（Y方向旋轉）、ROTZ（Z方向旋轉），根據(jù)實際分析，應用ALL DOF(全約束)；施加載荷操作如下：Solution/Define Loads