1、第 4 章 驅(qū)動機(jī)構(gòu)的計算 4.1 部件的選擇計算 需要作選擇計算的部件主要有電動機(jī)，減速器，制動器及帶制動輪的聯(lián)軸器。 4.1.1 電動機(jī)的選擇計算 電動機(jī)的靜功率可由下式確定： (kW) 0 6120 QV Nc a 3210 式中： 啟閉機(jī)最大起吊力(Kgf)，Q 起升速度(m/min)，V 啟閉機(jī)總效率， 0 減速器的效率， 1 開式齒輪的效率， 2 卷筒的效率 3 a滑輪組的效率。 查設(shè)計手冊可分別?。?0.93, =0.95, =0.97, a=0.966 1 2 3 可求得： =0.930.950.970.966=0.828 0 =5001032/61200.828=26.7(k

2、W) C N 根據(jù)閘門的運(yùn)行特點(diǎn)和起閉工作類型的劃分，將一次運(yùn)轉(zhuǎn)只有熟分鐘的電機(jī)工況一般定 為輕級工作類型（Jc=15%） ；若電機(jī)一次連續(xù)工作時間在 1030min 之間，運(yùn)轉(zhuǎn)后停歇時 間很長足以使其完全冷卻時，工況一般定為中級工作類型（Jc=25%） ；若一次連續(xù)工作時 間在 3060min 之間工況一般定為中級工作類型（Jc=40%） 。選出的電機(jī)一般不進(jìn)行發(fā)熱 預(yù)算。 起閉機(jī)工作時間可用下式計算 TH/V40/1.3928.78min30min 故所選電動機(jī)其工況為中級工作類型（Jc=25%）根據(jù)下式選用電動機(jī) 電 N C N 又KW NC 7 . 26 由此新編機(jī)械設(shè)計手冊表 271

3、9 可選用 YZR250 型電動機(jī)， =35kW. 電 N =715r/min d n 4.1.2 減速器的選擇計算 起升機(jī)構(gòu)的總傳動比為： i= 0 n nd = 0 n 0 D aV 式中： 電動機(jī)的額定轉(zhuǎn)速（r/min） d n 卷筒轉(zhuǎn)速（r/min） 0 n 滑輪組倍率a 卷筒計算直徑（m） 0 D 起升速度（）V 帶入數(shù)據(jù)可計算得： =2.84(r/min) 0 n 624 . 0 14 . 3 24 i=251.8 84 . 2 715 因一級圓柱開式齒輪傳動傳動比一般為 37，可取開式齒輪傳動比 i1=6 則減速器傳動比為：i2=i/i1=251.8/6=42 所選減速器的功率應(yīng)

4、稍大于電動機(jī)的靜功率，即： N=37kW 電 N 查新編機(jī)械設(shè)計手冊表 2249 可選用 QJRS-D40031.5 型，i2 =50, 高速軸許用功率 N=31.0kW,輸出轉(zhuǎn)矩為 21200Nm.此型號為二級的安裝尺寸，三級的傳動比。 故開式齒輪的傳動比為：i1=251.8/50=5 減速器的驗(yàn)算 減速器出力軸上的最大經(jīng)向力 P最大可認(rèn)為等于作用于開式齒輪輪齒上的作用力： )( 2 2 2 RN mZ M P 最大 式中 M2 -減速器低速軸上的扭矩 m -開式齒輪的模數(shù) Z2-大齒輪的齒數(shù) R-減速器輸出軸容許最大經(jīng)向載荷 由 M2=17403Nm m=12mm Z2=100 R可查新編

5、機(jī)械設(shè)計手冊表 22 51 可得R=37000N NRN P 3700029005 10012 174032 最大 經(jīng)校核符合要求 4.1.3 制動器的選擇計算 起升機(jī)構(gòu)制動器的制動力矩必須大于由重物產(chǎn)生的靜力矩，并使重物處于懸吊狀態(tài)時具 有足夠的安全裕度，選用時必須滿足： MK c M 式中： M制動器需用最大制動力矩（Nm） K制動安全系數(shù)，一般起升機(jī)構(gòu)為 K，取 K=22 滿載制動時制動軸上的靜力矩（Nm） c M 制動軸上靜力矩由下式?jīng)Q定： c M = (Nm) c M i2 0 a QD 得： = =1025.96(Nm) c M 8 . 25142 828. 06245002 制動

6、器許用最大制動力矩：M21025.96=2051.96 (Nm) 查機(jī)械設(shè)計手冊表 25.332 可選用JCZ500/80 型制動器，=2500Nm c M 4.1.4 帶制動輪聯(lián)軸器的選擇 帶制動輪聯(lián)軸器的選擇計算應(yīng)滿足下述三個條件： 聯(lián)軸器的制動輪直徑應(yīng)與制動器制動閘瓦的直徑相適應(yīng)； 聯(lián)軸器的最大允許扭轉(zhuǎn)力矩應(yīng)大于等于實(shí)際傳遞扭轉(zhuǎn)矩的兩倍 K=2 M Mm 聯(lián)軸器的最大扭轉(zhuǎn)力矩需大于所配用制動器的最大制動力矩 m M T M 聯(lián)軸器所傳遞的扭矩可由下式計算： M=n8 n M n 軸節(jié)的安全系數(shù)。對起升機(jī)構(gòu) n=1.5 8性動載系數(shù)。8=1.22.0 電動機(jī)額定力矩傳導(dǎo)計算零件上的力矩 n

7、 M 電動機(jī)額定力矩傳到計算零件上的力矩為： = n M n P9550 式中 電動機(jī)額定功率（KW）P n電動機(jī)額定轉(zhuǎn)速（n/min） 傳動機(jī)構(gòu)的效率=0.828 得： =955035/7150.828=387.1(Nm) n M 聯(lián)軸器傳遞的扭矩：M=1.5387.11.8=1045.17(Nm) 故所選聯(lián)軸器的最大扭轉(zhuǎn)力矩：1045.17Nm n M 而選擇聯(lián)軸器時同時應(yīng)滿足其實(shí)際轉(zhuǎn)數(shù)不得大于其許用最高轉(zhuǎn)數(shù)，故其許用最高轉(zhuǎn)數(shù)n 715r/min,查手冊可選用 NGCL9 型，公稱轉(zhuǎn)矩 Tn=14000Nm,許用轉(zhuǎn)速n=1500r/min 4.2 驅(qū)動機(jī)構(gòu)計算 卷筒軸的扭矩按下式計算： M

8、3= (kNm) 3 max 2 DCS 式中 鋼絲繩最大靜拉力（kN.m） max S 卷筒直徑（m）D C引至卷筒的鋼繩支數(shù) 卷筒效率 查手冊知：=0.966 3 3 代入數(shù)據(jù)，得： M3=64.76242/20.966=41621.4(N.m) 減速器低速軸（即開式齒輪小齒輪軸）上的扭矩為： M2=（N.m） 22 3 i 2M 式中 i2開式齒輪的傳動比 開式齒輪的傳動效率。查手冊可知：=0.95 2 2 代入數(shù)據(jù)， 得： M2=17403N.m 減速器高速軸（即電動機(jī)軸）上的扭矩為： M1=(N.m) 11 2 i 2M 式中 i1減速器的傳動比 減速器的傳動效率，由手冊可查得： =

9、0.93 1 1 代入數(shù)據(jù)，得： M1=374.26N.m 4.3 安全行程裝置 本機(jī)的安全行程裝置有高度指示器高度限位開關(guān)和負(fù)荷控制器。高度指示器可觀察和控制 閘門的準(zhǔn)確位置；高度限位開關(guān)限制閘門的上下極限位置；負(fù)荷控制器具有報警和斷電功能， 當(dāng)負(fù)荷達(dá)到額定負(fù)荷的 110%時，發(fā)出報警信號并自動切斷電路。 總結(jié) 此次設(shè)計的固定卷揚(yáng)式啟閉機(jī)是在給定基礎(chǔ)參數(shù)和前人的設(shè)計經(jīng)驗(yàn)的基礎(chǔ)上完成的。我 采用類比的方法，借鑒已有的經(jīng)驗(yàn)，再根據(jù)具體的實(shí)際情況加以變換改造，逐步形成自己的 設(shè)計。但由于在設(shè)計過程中，經(jīng)驗(yàn)和理論知識的不足，使得我在某些方面的設(shè)計有待進(jìn)一步 改進(jìn)和完善，這些問題有待于我進(jìn)一步的研究和

10、討論。 在設(shè)計過程中我遇到了許多意想不到的問題，經(jīng)過自己的摸索及同學(xué)的討論和老師的幫 助，困難得到了解決。經(jīng)過此次設(shè)計，我發(fā)現(xiàn)了以前學(xué)習(xí)中的薄弱環(huán)節(jié)，鍛煉和復(fù)習(xí)了所學(xué) 知識，使我知道在以后的學(xué)習(xí)和工作中應(yīng)該如何去作和作些什么，是本次設(shè)計的最大收獲。 主要參考文獻(xiàn) 1 徐 灝 主編 機(jī)械設(shè)計手冊 第（3）卷 北京機(jī)械工業(yè)出社 2002 2 編寫組 主編 實(shí)用機(jī)械設(shè)計手冊 上冊 機(jī)械工業(yè)出版社，1992 3 編寫組 主編 水電站設(shè)計手冊 水利電力出版社，1999 4 石殿鈞 主編 工程起重機(jī)械 水利電力出版社，1987 5 劉鴻文 主編 材料力學(xué) 上下冊 北京高等教育出版社，1999 6 孫桓 主

11、編 機(jī)械原理 北京高等教育出版社，2001 7 王公侃 主編 起重機(jī)械課程設(shè)計 北京中國工業(yè)出版，1965 8 邱宣懷 主編 機(jī)械設(shè)計手冊 第四版 高等教育出版社，2002 9 歐陽晶 主編 大峽水電站的結(jié)構(gòu)設(shè)計 機(jī)械工業(yè)出版社，1992 10 編寫組 主編 實(shí)用機(jī)械設(shè)計手冊 下冊 機(jī)械工業(yè)出版社，1992 11 張琳娜 主編 精度設(shè)計與質(zhì)量控制基礎(chǔ) 中國計量出版社，2000 12 孫桓 主編 機(jī)械原理 第六板 高等教育出版社，2000 13 哈工大 主編 理論力學(xué) 上下冊 高等教育出版社，1996 14 華中理工 主編 畫法幾何及機(jī)械制圖 第四版 高等教育出版社，1988 15 鄧文英 主編

12、 金屬工藝學(xué) 上下冊 第四版 高等教育出版社，1999 16 王先逵 主編 機(jī)械制造工藝學(xué) 機(jī)械工業(yè)出版社，1993 致謝 本次設(shè)計的順利完成，首先感謝蘇宗偉、袁志華兩位老師精心指導(dǎo)和大力幫助。她們時 刻關(guān)注了解設(shè)計的進(jìn)展情況，并提出很多寶貴意見，在此向她們致以深深的感謝！同時也得 到圖書館、機(jī)械系教研室、資料室、機(jī)電機(jī)房等單位多位老師的大力支持和幫助，再次也深 表謝意! 本課題由我單獨(dú)完成，雖然在設(shè)計過程中是獨(dú)立完成，但是有很多的難題是在同學(xué)們的 討論成果基礎(chǔ)上才得以正確順利的進(jìn)行。 經(jīng)過此次設(shè)計，我掌握了一些設(shè)計方法和步驟， 提高了把理論運(yùn)用于實(shí)際的能力，培養(yǎng)了綜合分析與解決工程問題的能力

13、和創(chuàng)新意識。最后 再次對指導(dǎo)和幫助我順利完成此次設(shè)計的老師和同學(xué)表示衷心的感謝！ The Effect of a Viscous Coupling Used as a Front-Wheel Drive Limited-Slip Differential on Vehicle Traction and Handling 1 ABCTRACT The viscous coupling is known mainly as a driveline component in four wheel drive vehicles. Developments in recent years, howeve

14、r, point toward the probability that this device will become a major player in mainstream front-wheel drive application. Production application in European and Japanese front-wheel drive cars have demonstrated that viscous couplings provide substantial improvements not only in traction on slippery s

15、urfaces but also in handing and stability even under normal driving conditions. This paper presents a serious of proving ground tests which investigate the effects of a viscous coupling in a front-wheel drive vehicle on traction and handing. Testing demonstrates substantial traction improvements whi

16、le only slightly influencing steering torque. Factors affecting this steering torque in front-wheel drive vehicles during straight line driving are described. Key vehicle design parameters are identified which greatly influence the compatibility of limited-slip differentials in front-wheel drive veh

17、icles. Cornering tests show the influence of the viscous coupling on the self steering behavior of a front-wheel drive vehicle. Further testing demonstrates that a vehicle with a viscous limited-slip differential exhibits an improved stability under acceleration and throttle-off maneuvers during cor

18、nering. 2 THE VISCOUS COUPLING The viscous coupling is a well known component in drivetrains. In this paper only a short summary of its basic function and principle shall be given. The viscous coupling operates according to the principle of fluid friction, and is thus dependent on speed difference.

19、As shown in Figure 1 the viscous coupling has slip controlling properties in contrast to torque sensing systems. This means that the drive torque which is transmitted to the front wheels is automatically controlled in the sense of an optimized torque distribution. In a front-wheel drive vehicle the

20、viscous coupling can be installed inside the differential or externally on an intermediate shaft. The external solution is shown in Figure 2. This layout has some significant advantages over the internal solution. First, there is usually enough space available in the area of the intermediate shaft t

21、o provide the required viscous characteristic. This is in contrast to the limited space left in todays front-axle differentials. Further, only minimal modification to the differential carrier and transmission case is required. In-house production of differentials is thus only slightly affected. Intr

22、oduction as an option can be made easily especially when the shaft and the viscous unit is supplied as a complete unit. Finally, the intermediate shaft makes it possible to provide for sideshafts of equal length with transversely installed engines which is important to reduce torque steer (shown lat

23、er in section 4). This special design also gives a good possibility for significant weight and cost reductions of the viscous unit. GKN Viscodrive is developing a low weight and cost viscous coupling. By using only two standardized outer diameters, standardized plates, plastic hubs and extruded mate

24、rial for the housing which can easily be cut to different lengths, it is possible to utilize a wide range of viscous characteristics. An example of this development is shown in Figure 3. 3 TRACTION EFFECTS As a torque balancing device, an open differential provides equal tractive effort to both driv

25、ing wheels. It allows each wheel to rotate at different speeds during cornering without torsional wind- up. These characteristics, however, can be disadvantageous when adhesion variations between the left and right sides of the road surface (split-) limits the torque transmitted for both wheels to t

26、hat which can be supported by the low- wheel. With a viscous limited-slip differential, it is possible to utilize the higher adhesion potential of the wheel on the high-surface. This is schematically shown in Figure 4. When for example, the maximum transmittable torque for one wheel is exceeded on a

27、 split- surface or during cornering with high lateral acceleration, a speed difference between the two driving wheels occurs. The resulting self-locking torque in the viscous coupling resists any further increase in speed difference and transmits the appropriate torque to the wheel with the better t

28、raction potential. It can be seen in Figure 4 that the difference in the tractive forces results in a yawing moment which tries to turn the vehicle in to the low-side, To keep the vehicle in a straight line the driver has to compensate this with opposite steering input. Though the fluid-friction pri

29、nciple of the viscous coupling and the resulting soft transition from open to locking action, this is easily possible, The appropriate results obtained from vehicle tests are shown in Figure 5. Reported are the average steering-wheel torque Ts and the average corrective opposite steering input requi

30、red to maintain a straight course during acceleration on a split-track with an open and a viscous differential. The differences between the values with the open differential and those with the viscous coupling are relatively large in comparison to each other. However, they are small in absolute term

31、s. Subjectively, the steering influence is nearly unnoticeable. The torque steer is also influenced by several kinematic parameters which will be explained in the next section of this paper. 4 FACTORS AFFECTING STEERING TORQUE As shown in Figure 6 the tractive forces lead to an increase in the toe-i

32、n response per wheel. For differing tractive forces, Which appear when accelerating on split-with limited-slip differentials, the toe-in response changes per wheel are also different. Unfortunately, this effect leads to an undesirable turn-in response to the low-side, i.e. the same yaw direction as

33、caused by the difference in the tractive forces. Reduced toe-in elasticity is thus an essential requirement for the successful front-axle application of a viscous limited-slip differential as well as any other type of limited-slip differential. Generally the following equations apply to the driving

34、forces on a wheel VT FF With Tractive Force T F Vertical Wheel Load V F Utilized Adhesion Coefficient These driving forces result in steering torque at each wheel via the wheel disturbance level arm “e” and a steering torque difference between the wheels given by the equation: = e T loHhiH FFe cos W

35、here Steering Torque Difference e T e=Wheel Disturbance Level Arm King Pin Angle hi=high-side subscript lo=low-side subscript In the case of front-wheel drive vehicles with open differentials, Ts is almost unnoticeable, since the torque bias () is no more than 1.35. loHhiT FF / For applications with

36、 limited-slip differentials, however, the influence is significant. Thus the wheel disturbance lever arm e should be as small as possible. Differing wheel loads also lead to an increase in Te so the difference should also be as small as possible. When torque is transmitted by an articulated CV-Joint

37、, on the drive side (subscript 1) and the driven side (subscript 2),differing secondary moments are produced that must have a reaction in a vertical plane relative to the plane of articulation. The magnitude and direction of the secondary moments (M) are calculated as follows (see Figure 8): Drive s

38、ide M1 = vv TT tan/)2/tan(2 Driven side M2 = vv TT tan/)2/tan(2 With T2 = dynT rF = TsystemJoTfint, 2 Where Vertical Articulation Angle v Resulting Articulation Angle Dynamic Wheel Radius dyn r Average Torque Loss T The component acts around the king-pin axis (see figure 7) as a steering torque per

39、cos2M wheel and as a steering torque difference between the wheels as follows: )tan/2/tan()sin/2/tan(cos 22liwhiw TTTTT where Steering Torque Difference T WWheel side subscript It is therefore apparent that not only differing driving torque but also differing articulations caused by various drivesha

40、ft lengths are also a factor. Referring to the moment-polygon in Figure 7, the rotational direction of M2 or respectively change, depending on the position of the wheel- T center to the gearbox output. For the normal position of the halfshaft shown in Figure 7(wheel-center below the gearbox output j

41、oint) the secondary moments work in the same rotational direction as the driving forces. For a modified suspension layout (wheel-center above gearbox output joint, i.e. negative) the v secondary moments counteract the moments caused by the driving forces. Thus for good compatibility of the front axl

42、e with a limited-slip differential, the design requires: 1) vertical bending angles which are centered around or negative () with same values of on 0 v 0 v v both left and right sides; and 2) sideshafts of equal length. The influence of the secondary moments on the steering is not only limited to th

43、e direct reactions described above. Indirect reactions from the connection shaft between the wheel-side and the gearbox-side joint can also arise, as shown below: Figure 9: Indirect Reactions Generated by Halfshaft Articulation in the Vertical Plane For transmission of torque without loss and both o

44、f the secondary moments acting vdvw on the connection shaft compensate each other. In reality (with torque loss), however, a secondary moment difference appears: WDDW MMM 12 With TTT WD22 The secondary moment difference is: DW M VW W VWWVDVDW TTDTwTT tan/2/tansin/tan 22/2 For reasons of simplificati

45、on it apply that and to give VVWVD TTTWD VVVDW TMtan/1sin/12/tan requires opposing reaction forces on both joints where . Due to the DW MLMF DWDW / joint disturbance lever arm f, a further steering torque also acts around the king-pin axis: LfMT DWf /cos loloDWhihiDWf LMLMfT/cos Where Steering Torqu

46、e per Wheel f T Steering Torque Difference f T Joint Disturbance Lever f Connection shaft (halfshaft) Length L For small values of f, which should be ideally zero, is of minor influence. f T 5EFFECT ON CORNERING Viscous couplings also provide a self-locking torque when cornering, due to speed differ

47、ences between the driving wheels. During steady state cornering, as shown in figure 10, the slower inside wheel tends to be additionally driven through the viscous coupling by the outside wheel. Figure 10: Tractive forces for a front-wheel drive vehicle during steady state cornering The difference b

48、etween 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 viscous coupling in a front-wheel drive vehicle on self-steering tends towards an understeering char

49、acteristic. This behavior is totally consistent with the handling bias of modern vehicles which all under steer during steady state cornering maneuvers. Appropriate test results are shown in figure 11. Figure 11: comparison between vehicles fitted with an open differential and viscous coupling durin

50、g steady state cornering. 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 slightly different radii. The difference between the driving force

51、s and the resulting yaw moment tries to restore the vehicle to straight-line running again (see figure 10). Although these directional deviations result in only small differences in wheel travel radii, the rotational differences especially at high speeds are large enough for a viscous coupling front

52、 differential to bring improvements in straight-line running. 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 viscous differentials, this spinning is limited

53、 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 Figure 12: tractive forces for a front-wheel drive vehicle with viscous limited-slip differential during acceleration in a bend The accel

54、eration capacity is thus improved, particularly when turning or accelerating out of a T-junction maneuver ( i.e. accelerating from a stopped position at a “T” intersection-right or left turn ). Figures 13 and 14 show the results of acceleration tests during steady state cornering with an open differ

55、ential and with viscous limited-slip differential . Figure 13: acceleration characteristics for a front-wheel drive vehicle with an open differential on wet asphalt at a radius of 40m (fixed steering wheel angle throughout test). Figure 14: Acceleration Characteristics for a Front-Wheel Drive Vehicl

56、e with Viscous Coupling on Wet Asphalt at a Radius of 40m (Fixed steering wheel angle throughout test) The vehicle with an open differential achieves an average acceleration of 2.0 while the 2 /sm vehicle with the viscous coupling reaches an average of 2.3 (limited by engine-power). 2 /sm 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 viscous coupling. During acceleration in a bend, front-wheel drive vehicles in general tend to under