Development of evolutionary cone type LSD for SUV/RV utilizing the axiomatic approach and the ultrasonic nano crystal surface modification technology

Surface topology, cone angle and the forces acting on the cone of the clutch type limited slip differential (LSD) are major design parameters for the bias ratio and the noise condition. Therefore much research has been dedicated to these developments but the results have been used to submit patents. A new cone type limited slip differential for sport utility vehicles and recreational vehicles, which has a very simple structure and easy compliance with the vehicle performance, has been developed by the axiomatic approach and the ultrasonic nano crystal surface modification (UNSM) technology. The design criteria and optimal value of the design parameters are determined by the axiomatic approach utilizing CAE tools. Test methodologies in a test rig and in a vehicle were also developed. Test results showed good performance of bias ratio and noise level but durability is still under testing. This study is an extension of F2006P266, FISITA 2006.     

Judder analysis of electronically controlled limited slip differential

The electronically controlled limited slip differential system used on the new Skyline contributes to improvements in vehicle dynamics. One important performance parameter that is improved is the start-off acceleration when one drive wheel is on an ultra-low friction surface. There was concern, however, that larger LSD torque might cause drivetrain judder due to the negative μ-v slope of the wet multiplate clutch used in the system. An analysis based on natural mode calculations clarified the mechanism generating judder, and the results of stability calculations revealed measures for improvements. As a result, the problem of self-excited vibration was resolved.     

机械式自动变速器起车过程综合控制

分析机械式自动变速器在各种工况下起车离合器接合过程，以起车冲击度和滑摩功均较小为原则，来实现离合器结合的平顺性。根据油门开度、发动机转速、输入轴转速计算发动机的负荷能力，控制离合器传递的扭矩使发动机输出扭矩与离合器扭矩匹配。另外建立滑摩功与离合器温升的模型，防止离合器摩镣片过温损坏。据此建立起车离合器控制MAP图，已应用于某车型的AMT样车上。     

Optimal control of motorsport differentials

Modern motorsport limited slip differentials (LSD) have evolved to become highly adjustable, allowing the torque bias that they generate to be tuned in the corner entry, apex and corner exit phases of typical on-track manoeuvres. The task of finding the optimal torque bias profile under such varied vehicle conditions is complex. This paper presents a nonlinear optimal control method which is used to find the minimum time optimal torque bias profile through a lane change manoeuvre. The results are compared to traditional open and fully locked differential strategies, in addition to considering related vehicle stability and agility metrics. An investigation into how the optimal torque bias profile changes with reduced track-tyre friction is also included in the analysis. The optimal LSD profile was shown to give a performance gain over its locked differential counterpart in key areas of the manoeuvre where a quick direction change is required. The methodology proposed can be used to find both optimal passive LSD characteristics and as the basis of a semi-active LSD control algorithm.     

Quasi-steady-state linearisation of the racing vehicle acceleration envelope: a limited slip differential example

In the motorsport environment, passive limited slip differentials are a well-established means of improving the traction limitation imposed by the open differential. Torque sensing types are highly adjustable, and can alter both the stability and agility of the vehicle in the various cornering phases of a typical manoeuvre. In this paper, an adjustable clutch plate or ‘Salisbury’ differential model is presented, which can significantly alter its torque bias characteristics through adjustments in the drive/coast ramp angle, the number of friction faces and preload. To allow robust evaluation of differential parameter changes on ultimate vehicle performance and handling balance, a unified acceleration or ‘GG’ diagram framework is then described. This builds on traditional GG diagram approaches, by using nonlinear constrained optimisation to define both the vehicle acceleration limits and a ‘feasibility’ region within the performance envelope. By linearising a seven degrees of freedom vehicle model at multiple operating points, eigenvalue and yaw rate response analysis is then used to establish contours of stability and agility throughout the GG envelope. This brings new insights into the way in which handling balance changes below and up to the vehicle's acceleration limits.     

DCT直线型换挡动力学仿真（续1）

为了使汽车冲击度和离合器滑摩功能够满足换挡品质的要求,文章对装有双离合器自动变速器（DCT）的汽车进行了动力学仿真分析,建立其变速器动力传动系统模型。并针对变速器直线型换挡过程中冲击度和滑摩功难以同时达到最优的问题,采用遗传算法对离合器油压值进行优化控制,获得油压-时间的最优控制曲线,将优化后的控制曲线代入仿真模型,结果表明,冲击度和滑摩功均达到较为理想的状态。     

ZL50型轮式装载机传动系统维修

介绍了ZL50型轮式装载机传动系统维修。包括离合器打滑引起油温过高、变速器换挡故障以及变速器常见故障。离合器打滑,使离合器片之间非正常摩擦产生大量的热,从而使油温过高。引起离合器打滑的原因主要有离合器片分离不彻底、过度磨损、翘曲变形、油压过低等。     

Dynamics Analysis of Torsional Vibration Induced by Clutch and Gear Set in Automatic Transmission

The torsional vibration generated during clutch engagement directly affects the shifting quality of automatic transmissions, where the noise source stems from both the clutch and the gear set. To predict the dynamical response and driveline oscillation, a comprehensive mathematical model of the vehicle powertrain equipped with automatic transmission is developed with consideration of nonlinearities in the clutch and the planetary gear set. For the clutch, the dynamics of stickslip is described for the transition between the slipping to locked states. The gear backlash model is used to analyze the rattle noise of the planetary gear set. Based on extensive powertrain simulations for the clutch engagement process, the magnitude of vibration propagation in the driveline are predicted to identify the primary factors of noise generation.     

Computation of surface temperatures and energy dissipation in dry friction clutches for varying torque with time

This paper describes an investigation of the energy dissipated and the surface temperature at any instant of dry friction clutch assuming torque being a function of time during the slipping. The equations of the thermal loads, total energy dissipated and relative velocity between contact surfaces are presented. Two-dimensional axisymmetric heat conduction problem of dry friction clutch is modeled mathematically and solved numerically using the finite element method to determine the temperature distribution during a single engagement assuming uniform wear between the contact surfaces. The comparison is made between temperature field assuming the torque varying with time and when it’s constant with time. Moreover, the effects of slipping time and dimensionless thickness of the pressure plate λ are to be investigated as well.     

汽车离合器常见故障分析及排除

汽车离合器作为传递和切断发动机动力的装置,离合压盘及摩擦片之间经常会处于相对运动状态,因磨损、变形或摩擦副匹配等因素,容易造成离合器故障,如起步抖动、异响、分离不清、打滑烧蚀等,从而影响车辆驾乘舒适性,甚至影响车辆的正常使用,文章通过对离合系统工作原理介绍,结合笔者多年对离合器问题处理的实际工作经验,对离合器常见故障的可能因素进行分析,并提供相应的解决方案。     

灰铸铁飞轮疲劳失效分析

大马力飞轮是商用车一款大马力发动机的零部件,其搭载大马力发动机为商用车提供动力总成。飞轮在工作期间,因经常与离合器摩擦,售后市场出现离合器打滑,起步困难、抖动较大等整车问题,拆解后发现,飞轮表面出现磨损不平、表面微裂纹为主要的失效形态的现象。     

捷达（Jetta）轿车离合器结构与常见故障诊断

本文把捷达轿车离合器总成分为三个组合部分，主动部分，从动部分和操纵机构，对各部分构成元件及其结构特点，功能做了详细的介绍，阐述了离合器接合和切断两种状态的工作原理，分析了离合器分离不彻底，打滑，发抖和异响等常见故障原因。     

基于驾驶机器人操纵的车辆起步质量研究

提出以车速跟踪偏差、冲击度、滑磨功为基于驾驶机器人操纵的车辆起步质量评价指标,选取发动机油门开度、离合器输出轴转速、离合器主从动轴转速差及离合器输出转速变化值作为起步过程控制参数进行车辆起步质量控制研究.确定了这些控制参数的控制规则,并提出了基于积分分离PID控制的起步离合器控制算法.试验结果表明,采用本文提出的起步质量控制策略与控制算法,可保证离合器接合过程中车速跟踪偏差不超过1.5 km/h、最大冲击度值为8.08 m/s3、起步时间约为1.5 s.     

P2混动自动变速器的离合器自适应控制

为了解决混合动力系统动力耦合的响应性和舒适性问题，建立混动离合器C0起动发动机过程和并联动力输出模式下的功率流模型。对C0起动发动机的控制过程进行仿真分析，针对C0的起动扭矩和电机的输出扭矩在时间和空间上的匹配问题，提出以换挡离合器的滑摩控制来进行缓冲的策略。为了实现稳定精确的发动机起动控制，消除各自的扭矩控制、液压系统特性的误差，提出C0离合器起动发动机的自适应控制和B1离合器滑摩自适应控制，以换挡离合器滑差和发动机转速的超调量为监控对象，对C0离合器各阶段压力控制参数进行自适应调整，以优化发动机起动过程。研究结果表明：通过换挡离合器的滑摩控制可以很好地解决C0离合器扭矩和电机扭矩的匹配问题，即使在换挡过程中对发动机起动也能保证良好的舒适性，并控制过程时间在1.5 s内；在整车试验过程中，通过对C0压力的自适应调整，发动机转速的超调和起动冲击问题均可以得到有效解决。     

转矩式限滑差速器对后轮驱动汽车操纵稳定性影响的研究

采用7自由度车辆动力学模型,对装用JA1020LSD型转矩式限滑差速器的后轮驱动汽车进行了操纵稳定性研究。通过仿真分析和道路试验研究表明:装用限滑差速器后增加了后轮驱动车辆的不足转向趋势,即改善了操纵稳定性,但转向力矩略有增加。     

后置客车底盘离合器系统的匹配设计

简要介绍东风后置客车底盘的结构特点,并对其离合器系统的转矩容量、单位面积上的压力、圆周速度、比滑磨功、踏板行程、踏板力作的功和踏板力进行匹配设计;阐述后置客车底盘离合器系统安装与调整工作及其应注意的问题。     

Model referenced adaptive control to compensate slip-stick transition during clutch engagement

Clutches are widely used in various vehicle powertrains. The engagement process of a friction clutch has three phases, i.e., open, slipping, and sticking. Transitions between different phases introduce a discontinuity to the powertrain dynamics, which has been neglected in previous research. A model referenced adaptive controller (MRAC), based on Popov hyper-stability criterion, is designed to compensate the discontinuity. MRAC adjusts the frictional torque along with the errors of the state variables compared with those of a referenced model. The designed MRAC is applied to a clutch in a bus. Simulation and experimental results under fast and slow startup cases show that MRAC can simultaneously reduce vehicle jerk and frictional dissipation when compared with the conventional controller.     

东海大桥预制箱梁滑移运输施工技术

上海市深水港工程东海大桥,上部结构预制箱梁在预制场内采用滑移方式运输。箱梁滑移采用MGB高分子聚合材料与镜面不锈钢板作为滑移面。介绍箱梁滑移方法和相应的技术构造措施。     

大功率自动变速器换挡离合器调压控制研究

为了改善大功率自动变速器换挡过程中换挡离合器（含湿式制动器和湿式离合器）油压的调控水平,提高车辆的换挡品质,从结构上在换挡离合器中设计平衡活塞来补偿离合器旋转离心的影响,并在排油回路中增加背压阀以消除活塞腔内空气造成的不确定性。通过对换挡执行系统结构进行分析,分别针对离合器活塞、电液调压过程及离合器滑摩过程进行模型计算,在此基础上,将惯性相的充油调压控制进行拆解,即在转矩相结束时刻初始常量的基础上叠加一阶控制过程,针对换挡过程中系统存在非线性干扰和参数不确定性的特点,结合系统特性的分阶段试验标定,制定了换挡离合器调压过程的滑模控制策略,并基于MATLAB环境对控制策略的正确性和有效性进行仿真分析,最后进行实车试验验证。研究结果表明：无论是制动器充油还是旋转离合器充油,控制策略均能将惯性相持续时间、换挡冲击和滑摩功率损失等控制在合理范围;控制策略具有良好的性能,旋转离合器和制动器都能实现稳健的惯性相调压控制。     

Development and implementation of a torque vectoring algorithm for an innovative 4WD driveline for a high-performance vehicle

The sporting spirit that characterises a high-performance car can be observed in certain technical solutions. The power distribution on the rear wheels is the simplest example of that. It is well known that rear-wheel drive (RWD) vehicles are more fun to drive and faster in their reactions. Unfortunately, they are also less intuitive and harder to control because of their natural oversteering behaviour. The idea of maintaining an RWD driveline in the future is not farseeing, because it would imply an excessive tyre dimension increasing to let the driver use all engine power in many cornering and low-friction conditions. The choice of adopting a part-time all-wheel drive (AWD) driveline comes from the will of enhancing the overall performance by using all the available friction every time that it is needed. It has to be kept into account that a normally aspirated motor of a sport car can supply 500–600 Hp nowadays, and that it will supply 700–800 Hp in the very near future. However, the proposed driveline has not to worsen the weight characteristics (mass and load distribution) that make an RWD vehicle better than other cars. Because of all these considerations and constraints, a new driveline system has been designed. It derives from an RWD driveline with a semi-active differential, to which has been added a controlled wet clutch that directly connects the engine to the front differential. This device allows the drive torque to be distributed between the two axles. It can be understood that in such a device, the torque distribution does not depend only on the central clutch action, but also on the engaged gear. Because of this particular layout, this system can not work in the whole gear range because of thermal problems due to kinematical reasons. So the centre clutch controller has to consider the gear position too. The control algorithms development was carried out using a vehicle model, which can precisely simulate the handling response, the powertrain dynamic, and the actuation system behaviour. Such a modelling precision required the development of a customised powertrain model library in Matlab/Simulink.