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1、精选优质文档-倾情为你奉上第4章 驱动机构的计算4.1部件的选择计算需要作选择计算的部件主要有电动机，减速器，制动器及带制动轮的联轴器。4.1.1 电动机的选择计算电动机的静功率可由下式确定： (kW)式中： 启闭机最大起吊力(Kgf)，起升速度(m/min)，启闭机总效率，减速器的效率，开式齿轮的效率，卷筒的效率a滑轮组的效率。查设计手册可分别取：=0.93, =0.95, =0.97, a=0.966可求得： =0.930.950.970.966=0.828 =5001032/61200.828=26.7(kW)根据闸门的运行特点和起闭工作类型的划分，将一次运转只有熟分钟的电机工况一般定为
2、轻级工作类型（Jc=15%）；若电机一次连续工作时间在1030min之间，运转后停歇时间很长足以使其完全冷却时，工况一般定为中级工作类型（Jc=25%）；若一次连续工作时间在3060min之间工况一般定为中级工作类型（Jc=40%）。选出的电机一般不进行发热预算。起闭机工作时间可用下式计算 TH/V40/1.3928.78min30min 故所选电动机其工况为中级工作类型（Jc=25%）根据下式选用电动机又由此新编机械设计手册表2719可选用YZR250型电动机， =35kW. =715r/min4.1.2 减速器的选择计算起升机构的总传动比为：i= 式中： 电动机的额定转速（r/min）卷筒
3、转速（r/min）滑轮组倍率卷筒计算直径（m）起升速度（）带入数据可计算得：=2.84(r/min)i=251.8因一级圆柱开式齿轮传动传动比一般为37，可取开式齿轮传动比i1=6则减速器传动比为：i2=i/i1=251.8/6=42 所选减速器的功率应稍大于电动机的静功率，即： N=37kW查新编机械设计手册表2249可选用QJRS-D40031.5型，i2 =50, 高速轴许用功率N=31.0kW,输出转矩为21200Nm.此型号为二级的安装尺寸，三级的传动比。故开式齿轮的传动比为：i1=251.8/50=5减速器的验算 减速器出力轴上的最大经向力P最大可认为等于作用于开式齿轮轮齿上的作用
4、力： 式中 M2 -减速器低速轴上的扭矩 m -开式齿轮的模数 Z2-大齿轮的齿数 R-减速器输出轴容许最大经向载荷 由M2=17403Nm m=12mm Z2=100 R可查新编机械设计手册表2251可得R=37000N 经校核符合要求4.1.3 制动器的选择计算 起升机构制动器的制动力矩必须大于由重物产生的静力矩，并使重物处于悬吊状态时具有足够的安全裕度，选用时必须满足： MK式中： M制动器需用最大制动力矩（Nm） K制动安全系数，一般起升机构为K，取K=2 满载制动时制动轴上的静力矩（Nm）制动轴上静力矩由下式决定： = (Nm)得： = =1025.96(Nm)制动器许用最大制动力矩
5、：M21025.96=2051.96 (Nm)查机械设计手册表25.332可选用JCZ500/80型制动器，=2500Nm4.1.4 带制动轮联轴器的选择带制动轮联轴器的选择计算应满足下述三个条件：联轴器的制动轮直径应与制动器制动闸瓦的直径相适应；联轴器的最大允许扭转力矩应大于等于实际传递扭转矩的两倍K=2联轴器的最大扭转力矩需大于所配用制动器的最大制动力矩联轴器所传递的扭矩可由下式计算：M=n8n 轴节的安全系数。对起升机构 n=1.58性动载系数。8=1.22.0 电动机额定力矩传导计算零件上的力矩电动机额定力矩传到计算零件上的力矩为：=式中 电动机额定功率（KW）n电动机额定转速（n/m
6、in）传动机构的效率=0.828得： =955035/7150.828=387.1(Nm)联轴器传递的扭矩：M=1.5387.11.8=1045.17(Nm)故所选联轴器的最大扭转力矩：1045.17Nm而选择联轴器时同时应满足其实际转数不得大于其许用最高转数，故其许用最高转数n715r/min,查手册可选用NGCL9型，公称转矩Tn=14000Nm,许用转速n=1500r/min4.2 驱动机构计算卷筒轴的扭矩按下式计算： M3= (kNm)式中 钢丝绳最大静拉力（kN.m） 卷筒直径（m） C引至卷筒的钢绳支数 卷筒效率 查手册知：=0.966代入数据，得： M3=64.76242/20.
7、966=41621.4(N.m)减速器低速轴（即开式齿轮小齿轮轴）上的扭矩为： M2=（N.m）式中 i2开式齿轮的传动比开式齿轮的传动效率。查手册可知：=0.95代入数据， 得： M2=17403N.m减速器高速轴（即电动机轴）上的扭矩为： M1=(N.m)式中 i1减速器的传动比减速器的传动效率，由手册可查得： =0.93代入数据，得： M1=374.26N.m4.3安全行程装置本机的安全行程装置有高度指示器高度限位开关和负荷控制器。高度指示器可观察和控制闸门的准确位置；高度限位开关限制闸门的上下极限位置；负荷控制器具有报警和断电功能，当负荷达到额定负荷的110%时，发出报警信号并自动切断
8、电路。总结此次设计的固定卷扬式启闭机是在给定基础参数和前人的设计经验的基础上完成的。我采用类比的方法，借鉴已有的经验，再根据具体的实际情况加以变换改造，逐步形成自己的设计。但由于在设计过程中，经验和理论知识的不足，使得我在某些方面的设计有待进一步改进和完善，这些问题有待于我进一步的研究和讨论。在设计过程中我遇到了许多意想不到的问题，经过自己的摸索及同学的讨论和老师的帮助，困难得到了解决。经过此次设计，我发现了以前学习中的薄弱环节，锻炼和复习了所学知识，使我知道在以后的学习和工作中应该如何去作和作些什么，是本次设计的最大收获。主要参考文献1 徐 灏 主编 机械设计手册 第（3）卷 北京机械工业出
9、社20022 编写组 主编 实用机械设计手册 上册 机械工业出版社，19923 编写组 主编 水电站设计手册 水利电力出版社，19994 石殿钧 主编 工程起重机械 水利电力出版社，19875 刘鸿文 主编 材料力学 上下册 北京高等教育出版社，19996 孙桓 主编 机械原理 北京高等教育出版社，20017 王公侃 主编 起重机械课程设计 北京中国工业出版，19658 邱宣怀 主编 机械设计手册 第四版 高等教育出版社，20029 欧阳晶 主编 大峡水电站的结构设计 机械工业出版社，199210 编写组 主编 实用机械设计手册 下册 机械工业出版社，199211 张琳娜 主编 精度设计与质量
10、控制基础 中国计量出版社，200012 孙桓 主编 机械原理 第六板 高等教育出版社，200013 哈工大 主编 理论力学 上下册 高等教育出版社，199614 华中理工 主编 画法几何及机械制图 第四版 高等教育出版社，198815 邓文英 主编 金属工艺学 上下册 第四版 高等教育出版社，199916 王先逵 主编 机械制造工艺学 机械工业出版社，1993 致谢本次设计的顺利完成，首先感谢苏宗伟、袁志华两位老师精心指导和大力帮助。她们时刻关注了解设计的进展情况，并提出很多宝贵意见，在此向她们致以深深的感谢！同时也得到图书馆、机械系教研室、资料室、机电机房等单位多位老师的大力支持和帮助，再次
11、也深表谢意!本课题由我单独完成，虽然在设计过程中是独立完成，但是有很多的难题是在同学们的讨论成果基础上才得以正确顺利的进行。 经过此次设计，我掌握了一些设计方法和步骤，提高了把理论运用于实际的能力，培养了综合分析与解决工程问题的能力和创新意识。最后再次对指导和帮助我顺利完成此次设计的老师和同学表示衷心的感谢！The Effect of a Viscous Coupling Used as a Front-Wheel Drive Limited-Slip Differential on Vehicle Traction and Handling1 ABCTRACTThe viscous coup
12、ling is known mainly as a driveline component in four wheel drive vehicles. Developments in recent years, however, 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 c
13、ars have demonstrated that viscous couplings provide substantial improvements not only in traction on slippery surfaces 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
14、a front-wheel drive vehicle on traction and handing. Testing demonstrates substantial traction improvements while 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
15、are identified which greatly influence the compatibility of limited-slip differentials in front-wheel drive vehicles.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 lim
16、ited-slip differential exhibits an improved stability under acceleration and throttle-off maneuvers during cornering.2 THE VISCOUS COUPLINGThe 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
17、coupling operates according to the principle of fluid friction, and is thus dependent on speed difference. 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 auto
18、matically controlled in the sense of an optimized torque distribution.In a front-wheel drive vehicle the 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 i
19、nternal solution. First, there is usually enough space available in the area of the intermediate shaft to 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
20、transmission case is required. In-house production of differentials is thus only slightly affected. Introduction 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
21、of equal length with transversely installed engines which is important to reduce torque steer (shown later 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 coupli
22、ng. By using only two standardized outer diameters, standardized plates, plastic hubs and extruded material 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
23、EFFECTSAs a torque balancing device, an open differential provides equal tractive effort to both driving 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
24、left and right sides of the road surface (split-) limits the torque transmitted for both wheels to that 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 s
25、hown in Figure 4.When for example, the maximum transmittable torque for one wheel is exceeded on a 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
26、 increase in speed difference and transmits the appropriate torque to the wheel with the better traction 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 li
27、ne the driver has to compensate this with opposite steering input. Though the fluid-friction principle 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 ar
28、e the average steering-wheel torque Ts and the average corrective opposite steering input required 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 coup
29、ling are relatively large in comparison to each other. However, they are small in absolute terms. 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 AFFEC
30、TING STEERING TORQUEAs shown in Figure 6 the tractive forces lead to an increase in the toe-in 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 effe
31、ct leads to an undesirable turn-in response to the low-side, i.e. the same yaw direction as 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
32、 type of limited-slip differential.Generally the following equations apply to the driving forces on a wheelWith Tractive Force Vertical Wheel Load Utilized Adhesion CoefficientThese driving forces result in steering torque at each wheel via the wheel disturbance level arm “e” and a steering torque d
33、ifference between the wheels given by the equation:=Where Steering Torque Difference e=Wheel Disturbance Level Arm King Pin Angle hi=high-side subscript lo=low-side subscriptIn the case of front-wheel drive vehicles with open differentials, Ts is almost unnoticeable, since the torque bias () is no m
34、ore than 1.35.For applications with 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 tran
35、smitted by an articulated CV-Joint, 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
36、as follows (see Figure 8):Drive side M1 =Driven side M2 =With T2 = =Where Vertical Articulation Angle Resulting Articulation Angle Dynamic Wheel Radius Average Torque LossThe component acts around the king-pin axis (see figure 7) as a steering torque per wheel and as a steering torque difference bet
37、ween the wheels as follows: where Steering Torque Difference WWheel side subscriptIt is therefore apparent that not only differing driving torque but also differing articulations caused by various driveshaft lengths are also a factor. Referring to the moment-polygon in Figure 7, the rotational direc
38、tion of M2 or respectively change, depending on the position of the wheel-center to the gearbox output.For the normal position of the halfshaft shown in Figure 7(wheel-center below the gearbox output joint) the secondary moments work in the same rotational direction as the driving forces. For a modi
39、fied suspension layout (wheel-center above gearbox output joint, i.e. negative) the secondary moments counteract the moments caused by the driving forces. Thus for good compatibility of the front axle with a limited-slip differential, the design requires: 1) vertical bending angles which are centere
40、d around or negative () with same values of on 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 the direct reactions described above. Indirect reactions from the connection shaft between the wheel-side and the
41、gearbox-side joint can also arise, as shown below:Figure 9: Indirect Reactions Generated by Halfshaft Articulation in the Vertical PlaneFor transmission of torque without loss and both of the secondary moments acting on the connection shaft compensate each other. In reality (with torque loss), howev
42、er, a secondary moment difference appears: With The secondary moment difference is:For reasons of simplification it apply that and to give requires opposing reaction forces on both joints where . Due to the joint disturbance lever arm f, a further steering torque also acts around the king-pin axis:W
43、here Steering Torque per Wheel Steering Torque Difference Joint Disturbance Lever Connection shaft (halfshaft) LengthFor small values of f, which should be ideally zero, is of minor influence.5EFFECT ON CORNERINGViscous couplings also provide a self-locking torque when cornering, due to speed differ
44、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 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 viscous coupling in a front-wheel drive vehicle