外文翻譯-- 黏性連接器用作前輪驅(qū)動限制滑移差速器對汽車牽引和操縱的影響

1、<p>　　畢業(yè)設(shè)計(論文)外文資料翻譯</p><p>　　系　　部： 機械工程系 </p><p>　　專 業(yè)： 機械工程及自動化 </p><p>　　姓 名： </p><p>　　學

2、 號： </p><p>　　外文出處：The Effect of a Viscous Coupling Used as a </p><p>　　Front-Wheel Drive Limited-Slip Differential </p><p>　　on

3、 Vehicle Traction and Handling </p><p>　　附 件：1.外文資料翻譯譯文；2.外文原文。 </p><p>　　附件1：外文資料翻譯譯文</p><p>　　黏性連接器用作前輪驅(qū)動限制滑移差速器對汽車牽引和操縱的影響</p><p><

4、;b>　　5轉(zhuǎn)彎時的效應</b></p><p>　　扭轉(zhuǎn)時由于驅(qū)動輪的速度不相等，黏性連接器也提供一個自瑣的扭轉(zhuǎn)力矩。如圖表10所示，在平穩(wěn)轉(zhuǎn)向過程中，速度較慢的內(nèi)側(cè)車輪被外側(cè)車輪黏性連接器施加的一個附加的驅(qū)動力。</p><p>　　如圖表10：前輪驅(qū)動力的汽車穩(wěn)定狀態(tài)下轉(zhuǎn)向時的牽引力。</p><p>　　不同的牽引力和導致一個側(cè)偏力矩MCO

5、G，它必須被一個較大的側(cè)偏力補償，因此在前軸有一個大的滑動角af。因此前驅(qū)動輪的汽車自動轉(zhuǎn)向裝置上黏性連接器的影響趨向一個在轉(zhuǎn)向裝置狀態(tài)下的特性。這個運動方式整體上和所有轉(zhuǎn)向操縱下在穩(wěn)定狀態(tài)下轉(zhuǎn)彎移動時的現(xiàn)代汽車操縱方式的偏重心相一致.合適的試驗結(jié)果如圖表11所示。</p><p>　　如圖表11：安裝有開式差速器的汽車餓安裝有黏性連接器的汽車在穩(wěn)定狀態(tài)下轉(zhuǎn)彎時的對比</p><p>　　

6、如圖表10所示在轉(zhuǎn)彎時不對稱的牽引力干擾也會改進汽車的直線行駛。每一次偏離正常的直線方向都會引起車輪以輕微的不同半徑滾動。驅(qū)動力和產(chǎn)生的側(cè)偏力矩差會使汽車重新回到直線行駛（如圖表10）。</p><p>　　雖然這些方向的偏離引起僅僅很小的車輪滾動半徑差，但是旋轉(zhuǎn)的偏差尤其在高速時對于一個黏性連接器前差速器是足夠?qū)⑵噹У街本€上行駛的。</p><p>　　安裝有開式差速器的高動力前輪驅(qū)動

7、汽車當以低檔加速離開緊急轉(zhuǎn)角時通常旋轉(zhuǎn)它們的內(nèi)側(cè)車輪。安裝有限制滑動黏性差速器，這個旋轉(zhuǎn)是有限的并且有不同車輪的速度差產(chǎn)生的扭轉(zhuǎn)力為外側(cè)的驅(qū)動輪提供附加的牽引力效果。這顯示在圖表12中。</p><p>　　如圖表12：裝有黏性限制滑動差速器的前輪驅(qū)動汽車在轉(zhuǎn)道上加速時的牽引力</p><p>　　特別地當行駛或加速離開一個T形交叉路口加速能力就這樣被改善（也就是說在T形路口橫切向右或向左

8、從停止位置加速）。</p><p>　　圖表13和14顯示了裝有開式差速器和裝有黏性限制滑動差速器在穩(wěn)定狀態(tài)下轉(zhuǎn)彎過程中加速試驗的結(jié)果。</p><p>　　如圖表13所示：裝有一個開式差速器的前輪驅(qū)動汽車在半徑為40m的濕瀝青彎曲路面上加速特性（實驗過程中安裝有轉(zhuǎn)向裝置輪角測試儀）</p><p>　　如圖表14所示：裝有一個黏性連接器的前輪驅(qū)動汽車在半徑為40m

9、的濕瀝青彎曲路面上加速特性（實驗過程中安裝有轉(zhuǎn)向裝置輪角測試儀）</p><p>　　安裝有一個開式差速器的汽車平均加速度為同時裝有黏性連接器的汽車平均加速度達到（被發(fā)動機功率限制）。在這些試驗中，由內(nèi)側(cè)的從動輪引起的最大速度差，被從帶有開式差速器的240rpm減少到帶有黏性連接器的100rpm。</p><p>　　在彎道上加速行駛時，前輪驅(qū)動的汽車通常處在操縱狀態(tài)下要多于其勻速行駛的狀

10、態(tài)。前輪傳遞側(cè)偏力潛能降低的原理是由于重心移到后軸車輪并且在驅(qū)動輪上增加了縱向力。在一個開式環(huán)形控制循環(huán)測試中這個能夠看出在開始加速以后（時間為0在圖表13和14中）偏跑速度（跑偏率）的降低。從圖表13和14中還可以看出開始加速時裝有開式差速器汽車的跑偏率比裝有黏性連接器汽車的下降的更快。然而，在開始加速大約2秒后，黏性連接的汽車的跑偏率下降斜率增加高于裝有開式差速器 的汽車。</p><p>　　安裝有限制滑動

11、前差速器的汽車在轉(zhuǎn)彎過程中加速時具有一個更穩(wěn)定的最初反應比裝有開式差速器的汽車，降低它的操縱狀態(tài)。這是因為內(nèi)側(cè)驅(qū)動輪的高滑動通過黏性連接器產(chǎn)生一個增加的驅(qū)動力到外側(cè)車輪，這在圖表12中有解釋。前輪牽引力的不平衡導致在行駛方向上的偏跑力矩，反對操縱狀態(tài)。</p><p>　　當驅(qū)動輪的附著限制是超出的,安裝黏性連接器的汽車處于操縱狀態(tài)比安裝有開式差速器的汽車更明顯(這里,開始加速后2 秒)。在非常低的摩擦力表面，例

12、如雪或者冰，當裝有限制滑動差速器的汽車在曲線路面上加速時更強的操縱性被期望因為通過黏性連接器連接的驅(qū)動輪更容易旋轉(zhuǎn)（動力轉(zhuǎn)向裝置）。然而，這個特性能很容易地被駕駛員或者自動節(jié)氣門調(diào)節(jié)牽引系統(tǒng)控制。在這些情況下比后輪驅(qū)動的汽車更容易控制。在轉(zhuǎn)彎過程中當加速時它能夠防止動力過分操縱?？紤]到，所有的情況，裝配有一個黏性連接器的汽車在加速過程中具有穩(wěn)定的加速行動方式在光滑路面上只有小的缺點。</p><p>　　通過突然

13、釋放加速器，在轉(zhuǎn)彎過程中節(jié)氣門關(guān)閉的反應，通常導致前輪驅(qū)動的汽車改換方向（節(jié)氣門關(guān)閉超出了操縱）。高動力的模型能得到高側(cè)偏加速度顯示出最大規(guī)模的反應。這個節(jié)氣門關(guān)閉反應有幾個原因例如運動學上的影響，或者，當汽車降低速度試著以一個較小的轉(zhuǎn)變半徑通過時。然而，實質(zhì)上的原因，是動力的重心從后軸轉(zhuǎn)移到前軸，這會導致前軸降低滑動角。后軸增加滑動角。因為，后軸車輪不傳遞驅(qū)動力矩，在這種情況下在后軸上的影響比前軸上的影響更大。在節(jié)氣門關(guān)閉之前（如圖表

14、10）。前輪上的驅(qū)動力不再滾動或者以后制動力，黏性裝置汽車這個解釋在圖表15中。</p><p>　　如圖表15：安裝有黏性限制滑動差速器前輪驅(qū)動的汽車當轉(zhuǎn)變時關(guān)閉節(jié)氣門后移動立刻產(chǎn)生的制動力</p><p>　　隨著內(nèi)側(cè)的車輪繼續(xù)比外側(cè)車輪更慢的轉(zhuǎn)動，黏性聯(lián)結(jié)器給外側(cè)車輪提供更大的制動力。由于前輪力的不同圍繞著汽車重量的中心會產(chǎn)生一個抵消正常轉(zhuǎn)向反應的側(cè)偏力矩MCOG.。</p&g

15、t;<p>　　將安裝有開式差速器的汽車和裝有黏性聯(lián)結(jié)器的在關(guān)閉節(jié)氣門的移動過程中轉(zhuǎn)向方式進行比較時，如圖表16和17所示，安裝有黏性差速器的兩個驅(qū)動輪子之間速度差是降低的。</p><p>　　圖表16在轉(zhuǎn)彎半徑為40米（不封閉的環(huán)形）的濕瀝青路面上安裝有開式差速器前輪驅(qū)動汽車的節(jié)氣門關(guān)閉特性</p><p>　　如圖表17在轉(zhuǎn)彎半徑為40米（不封閉的環(huán)形）的濕瀝青路面上安

16、裝有黏性聯(lián)結(jié)器前輪驅(qū)動汽車的節(jié)氣門關(guān)閉特性</p><p>　　安裝有開式差速器的汽車側(cè)偏速度（側(cè)偏率），和相對的側(cè)偏角（除汽車保持繼續(xù)在穩(wěn)定狀態(tài)下轉(zhuǎn)彎的側(cè)偏角之外）在節(jié)氣門關(guān)閉后（時間為零如圖表14和15）顯示一個非常明顯的增加。在安裝有一個黏性的限制滑動差速器的汽車上節(jié)氣門關(guān)閉后側(cè)偏率的突然增加和相對側(cè)偏角的增加都有很大的降低。</p><p>　　例如在一個彎道上隨著半徑的增加，一上

17、正常的駕駛一個超大號的前輪驅(qū)動汽車的人通常僅僅的慣常的空檔的操縱裝置下的汽車操縱方式，然后駕駛員忽然驚奇并且在節(jié)氣門突然的釋放后會有有力的操縱反應。如果駕駛員對情況的反應不正確汽車將進一步惡化汽車離開車道到曲線的內(nèi)側(cè)的事故是這個事件的驗證。因此黏性聯(lián)結(jié)器為一個正常的駕駛員改善節(jié)氣門關(guān)閉的行為方式當保持可控制，可預言的并且安全駕駛時。</p><p>　　雖然這也許會被認為是一個負面影響而且對于一輛安裝有前黏性聯(lián)結(jié)

18、器的汽車來說當安裝YMR計算程序就能很容易地被修正，但是汽車試驗已經(jīng)證明這個影響是很小的，實際上不需要專門的新的ABS/YMR計算程序的開發(fā)。一些典型的求平均的測試結(jié)果被總結(jié)如圖表19。</p><p>　　如圖表19：結(jié)果構(gòu)成了帶有YMR在滑動系數(shù)為（V0=50mph,三檔，閉環(huán)）上的ABS自動測試在圖表19的左側(cè)顯示了在制動過程中有第一個ABS控制循環(huán)產(chǎn)生的最大速度差的比較。很明顯，黏性聯(lián)結(jié)器減小了速度差。當

19、黏性聯(lián)結(jié)器抵消YMR時，要求操縱車輪角在制動第一秒鐘從39度增加到51度保持汽車在直線方向上（圖表19，中部）。由于大多數(shù)汽車和ABS制造廠家認為90度是達到臨界狀態(tài)的限制，所以這能被接受。最后，在高值的一側(cè)通過黏性聯(lián)結(jié)器產(chǎn)生的一個增加的自鎖扭轉(zhuǎn)力。車輪制動力，一輛稍稍的高一些的汽車保持減速（圖表19右側(cè)）</p><p><b>　　6總結(jié)</b></p><p>

20、　　總之，黏性聯(lián)結(jié)器在前軸差速器的試用能被證實。它也明確地影響整個汽車的控制和穩(wěn)定，只是稍微地，但是可以接受的在扭轉(zhuǎn)力操縱上的影響。</p><p>　　為了減小不想要的扭轉(zhuǎn)力操縱的影響一個基本的設(shè)計準則被給出：</p><p>　　1 由于縱向載荷改變產(chǎn)生的警覺反應必須盡可能的小</p><p>　　2 主銷軸線和車輪中心之間的距離必須盡可能的小</p>

21、;<p>　　3 垂直彎曲角變化范圍應該接近零（或者為負值）</p><p>　　4 兩側(cè)的垂直彎曲角應該一樣</p><p><b>　　5 側(cè)軸應該等長</b></p><p>　　在扭轉(zhuǎn)力操縱上小的影響是聯(lián)結(jié)處的干擾常數(shù)不管什么理由這個常數(shù)的理想值是零。帶有和不帶有ABS的制動系統(tǒng)僅僅是黏性聯(lián)結(jié)器不重要的影響。在前輪驅(qū)動的汽

22、車上通過黏性的限制滑動差速器牽引力有著很重要的改善。</p><p>　　前輪驅(qū)動汽車獨立的轉(zhuǎn)向裝置的行動方式在操縱狀態(tài)的方向下被黏性限制滑動差速器稍稍地影響。在轉(zhuǎn)彎過程中節(jié)氣門關(guān)閉和加速改進的反應使前軸安裝有黏性聯(lián)結(jié)器的汽車更穩(wěn)定，更可預見而且更安全。</p><p>　　附件2：外文原文（復印件）</p><p>　　5．EFFECT ON CORNERING&

23、lt;/p><p>　　Viscous couplings also provide a self-locking torque when cornering, due to speed differences between the driving wheels. During steady state cornering, as shown in figure 10, the slower inside whee

24、l tends to be additionally driven through the viscous coupling by the outside wheel.</p><p>　　Figure 10: Tractive forces for a front-wheel drive vehicle during steady state cornering </p><p>　　T

25、he difference between the Tractive forces Dfr and Dfl results in a yaw moment MCOG, which has to be compensated by a higher lateral force, and hence a larger slip angle af at the front axle. Thus the influence of a visco

26、us coupling in a front-wheel drive vehicle on self-steering tends towards an understeering characteristic. This behavior is totally consistent with the handling bias of modern vehicles which all under steer during steady

27、 state cornering maneuvers. Appropriate test results are sh</p><p>　　Figure 11: comparison between vehicles fitted with an open differential and viscous coupling during steady state cornering.</p><

28、;p>　　The asymmetric distribution of the tractive forces during cornering as shown in figure 10 improves also the straight-line running. Every deviation from the straight-line position causes the wheels to roll on slig

29、htly different radii. The difference between the driving forces and the resulting yaw moment tries to restore the vehicle to straight-line running again (see figure 10).</p><p>　　Although these directional d

30、eviations result in only small differences in wheel travel radii, the rotational differences especially at high speeds are large enough for a viscous coupling front differential to bring improvements in straight-line run

31、ning.</p><p>　　High powered front-wheel drive vehicles fitted with open differentials often spin their inside wheels when accelerating out of tight corners in low gear. In vehicles fitted with limited-slip v

32、iscous differentials, this spinning is limited and the torque generated by the speed difference between the wheels provides additional tractive effort for the outside driving wheel. this is shown in figure 12</p>

33、<p>　　Figure 12: tractive forces for a front-wheel drive vehicle with viscous limited-slip differential during acceleration in a bend </p><p>　　The acceleration capacity is thus improved, particularly w

34、hen turning or accelerating out of a T-junction maneuver ( i.e. accelerating from a stopped position at a “T” intersection-right or left turn ).</p><p>　　Figures 13 and 14 show the results of acceleration te

35、sts during steady state cornering with an open differential and with viscous limited-slip differential .</p><p>　　Figure 13: acceleration characteristics for a front-wheel drive vehicle with an open differen

36、tial on wet asphalt at a radius of 40m (fixed steering wheel angle throughout test).</p><p>　　Figure 14: Acceleration Characteristics for a Front-Wheel Drive Vehicle with Viscous Coupling on Wet Asphalt at a

37、 Radius of 40m (Fixed steering wheel angle throughout test)</p><p>　　The vehicle with an open differential achieves an average acceleration of 2.0 while the</p><p>　　vehicle with the viscous co

38、upling reaches an average of 2.3 (limited by engine-power). In these tests, the maximum speed difference, caused by spinning of the inside driven wheel was reduced from 240 rpm with open differential to 100 rpm with the

39、viscous coupling.</p><p>　　During acceleration in a bend, front-wheel drive vehicles in general tend to understeer more than when running at a steady speed. The reason for this is the reduction of the potent

40、ial to transmit lateral forces at the front-tires due to weight transfer to the rear wheels and increased longitudinal forces at the driving wheels. In an open loop control-circle-test this can be seen in the drop of the

41、 yawing speed (yaw rate) after starting to accelerate (Time 0 in Figure 13 and 14). It can also be t</p><p>　　The vehicle with the limited slip front differential thus has a more stable initial reaction unde

42、r accelerating during cornering than the vehicle with the open differential, reducing its understeer. This is due to the higher slip at the inside driving wheel causing an increase in driving force through the viscous co

43、upling to the outside wheel, which is illustrated in Figure 12. the imbalance in the front wheel tractive forces results in a yaw moment acting in direction of the turn, countering t</p><p>　　When the adhes

44、ion limits of the driving wheels are exceed, the vehicle with the viscous coupling understeers more noticeably than the vehicle with the open differential (here, 2 seconds after starting to accelerate). On very low frict

45、ion surfaces, such as snow or ice, stronger understeer is to be expected when accelerating in a curve with a limited slip differential because the driving wheels-connected through the viscous coupling-can be made to spin

46、 more easily (power-under-steering). This char</p><p>　　Throttle-off reactions during cornering, caused by releasing the accelerator suddenly, usually result in a front-wheel drive vehicle turning into the t

47、urn (throttle-off oversteering ). High-powered modeles which can reach high lateral accelerations show the heaviest reactions. This throttle-off reaction has several causes such as kinematic influence, or as the vehicle

48、attempting to travel on a smaller cornering radius with reducing speed. The essential reason, however, is the dynamic weight tran</p><p>　　Figure 15:Baraking Forces for a Front-Wheel Drive Vehicle with Visco

49、us Limited-Slip Differential Immediately after a Throttle-off Maneuver While Cornering</p><p>　　As the inner wheel continued to turn more slowly than the outer wheel, the viscous coupling provides the outer

50、wheel with the larger braking force . The force difference between the front-wheels applied around the center of gravity of the vehicle causes a yaw moment that counteracts the normal turn-in reaction.</p><p&

51、gt;　　When cornering behavior during a throttle-off maneuver is compared for vehicles with open differentials and viscous couplings, as shown in Figure 16 and 17, the speed difference between the two driving wheels is red

52、uced with a viscous differential.</p><p>　　Figure 16: Throttle-off Characteristics for a Front-Wheel Drive Vehicle with an open Differential on Wet Asphalt at a Radius of 40m (Open Loop)</p><p>

53、　　Figure 17:Throttle-off Characteristics for a Front-Wheel Drive Vehicle with Viscous Coupling on Wet Asphalt at a Radius of 40m (Open Loop)</p><p>　　The yawing speed (yaw rate), and the relative yawing angl

54、e (in addition to the yaw angle which the vehicle would have maintained in case of continued steady state cornering) show a pronounced increase after throttle-off (Time=0 seconds in Figure 14 and 15) with the open differ

55、ential. Both the sudden increase of the yaw rate after throttle-off and also the increase of the relative yaw angle are significantly reduced in the vehicle equipped with a viscous limited-slip differential.</p>&

56、lt;p>　　A normal driver os a front-wheel drive vehicle is usually only accustomed to neutral and understeering vehicle handing behavior, the driver can then be surprised by sudden and forceful oversteering reaction aft

57、er an abrupt release of the throttle, for example in a bend with decreasing radius. This vehicle reaction is further worsened if the driver over-corrects for the situation. Accidents where cars leave the road to the inne

58、r side of the curve is proof of this occurrence. Hence the viscous cou</p><p>　　Although this might be considered as a negative effect and can easily be corrected when setting the YMR algorithm for a vehicle

59、 with a front viscous coupling, vehicle tests have proved that the influence is so slight that no special development of new ABS/YMR algorithms are actually needed. Some typical averaged test results are summarized in Fi

60、gure 19.</p><p>　　figure 19 : results form ABS braking tests with YMR on split-μ(Vo=50 mph, 3rd Gear, closed loop ) in figure 19 on the left a comparison of the maximum speed difference which occurred in th

61、e first ABS control cycle during braking is shown. It is obvious that the viscous coupling is reducing this speed difference. As the viscous coupling counteracts the YMR, the required steering wheel angle to keep the veh

62、icle in straight direction in the first second of braking increased from 39° to 51° (figure</p><p><b>　　6．summary</b></p><p>　　in conclusion,it can be established that the

63、application of a viscous coupling in a front-axle differential. It also positively influences the complete vehicle handling and stability , with only slight, but acceptable influence on torques-steer.</p><p>

64、;　　To reduce unwanted torque-steer effects a basic set of design rules have been established:</p><p>　　Toe-in response due to longitudinal load change must be as small as possible .</p><p>　　Dis

65、tance between king-pin axis and wheel center has to be as small as possible.</p><p>　　Vertical bending angle-rang should be centered around zero(or negative).</p><p>　　vertical bending angles sh

66、ould be the same for both sides.</p><p>　　Sideshafts should be of equal length.</p><p>　　Of minor influence on torque-steer is the joint disturbance lever arm which should be ideally zero for o

67、ther reasons anyway. Braking with and without ABS is only negligibly influenced by the viscous coupling. Traction is significantly improved by the viscous limited slip differential in a front-wheel drive vehicle.</p

68、><p>　　The self-steering behavior of a front-wheel drive vehicle is slightly influenced by a viscous limited slip differential in the direction of understeer. The improved reactions to throttle-off and accelera