【作者】 孙中辉；

【导师】 李幼德；

【作者基本信息】 吉林大学 ， 车辆工程， 2010， 博士

【摘要】 一汽某重型牵引车是解放品牌的畅销主打车型,其整车振动问题始终困扰着工程技术人员。本文针对一汽某重型牵引车的整车振动问题,探索一些切实可行的解决办法。文中运用振动理论,分别分析了悬架刚度,传动轴的工艺误差、装配误差,簧载质量,后桥速比等参数变化对整车振动的影响。在历经三年的课题研究过程中,主要工作内容有以下几个方面:首次通过等效变换的方式对常规振动模型进行改进,将前、后桥的加速度信号作为模型的输入信号。由于此信号是路面经过轮胎过滤后的测量信号,更加真实、准确,非常具有工程实用价值。首次利用近似等效的方式,使振动模型输入信号具有可移植性,探讨了两个典型问题:1)悬架刚度优化模型中的输入信号随着悬架刚度的变化而变化;2)载货汽车使用中,簧载质量是在一定载荷范围内随机变化的,簧载质量的变化导致模型输入信号的变化。首次利用矢量方法分析传动轴的运动过程,用简单方法解决了复杂问题。考虑后桥跳动的前提下,针对不同路面分别进行了传动轴的运动学仿真研究。建立了包含传动轴离心力的整车振动模型。通过正交试验方法,利用改进的车辆振动模型,对传动轴的多个参数分别进行仿真研究。应用遗传算法,对问题车辆的悬架刚度参数进行优化。在悬架刚度不变的条件下,通过优化匹配鞍座载质量、后桥速比和鞍座前置距等参数,降低了整车振动。更多还原

【Abstract】 It has been found in the present process of production that many vehicles’vibrations are caused by unbalance of transmission shaft. During the vehicle design, designers closely concern the vibrations of transmission shaft, and hope to acquire the quantitative relationship about vibrations between transmission shaft and vehicle.In this paper, in conjunction with FAW Group Corporation R&D Center-related research carried out, the FAW vehicle vibrations are conducted in-depth explorations. The content of this paper is the basis of vibration theory, and dual-axis of heavy vehicles’vibrations and their transmission shaft’s optimal matching are studied. The corresponding vibration in the vehicle modeling, dynamics analysis of rear axle shaft, transmission shaft’s optimal matching and fault vehicle’s optimal matching the four aspects carried out with a certain depth of exploration and study, and obtained some useful conclusions.1. Improvement of the Vehicle Vibrant ModelIt is very important for us to establish reasonable vehicle vibrant model, while vehicle vibration is considered. The main relevant research method of the vehicle vibrant model both in China and abroad is taking terrain displacement signal as the input signal of multi-degree of freedom vehicle model, which needs to build complex terrain model and tire model,but it is very difficult to build them till now.Accelerometer has the advantage of small volume and high precision, and it is convenient to use as engineering survey, so it is frequently used to analyze the vibration problem of vehicle. The traditional vehicle vibrant model is improved by the method of coordinate transform, by which the acceleration signal of the front axle and rear drive axle is used as the model input signal. Because of the input signal which is measured after being filtered by tires and bears tire enveloping properties, it will be more authentic and practical. Approximate equivalent and coordinate transform are firstly used to resolving the transplantation difficulty about the input signal of automobile dependent suspension optimization model. Two types of problems are discussed: 1) the input signal is changed by changing with suspension stiffness in the suspension optimization model; 2) the input signal is changed by changing with sprung mass during sprung mass randomly varied in certain extent. Without losing the accuracy of the input signal, the model can be used into not only the suspension optimization model, but also all kinds of deforming vehicles’calculation models which have identical suspension and different sprung mass. Thus, the improved vibration model is more practical in engineering. Compared with the traditional automobile dependent suspension optimization model,not only the input signal is convenient to attain, but also the input signal is changed by changing with suspension stiffness. Thus, the comparison between simulation and test shows that not only the calculation accuracy of model is improved, but also the model is more practical in engineering.2. Kinematics Characteristics of Rear-axle Transmission ShaftA new method of space analytic geometry is presented, by which the kinematics characteristics of single cross universal joint is analyzed and the dynamic model of the rotate speed, the angular acceleration and the torque about driven shaft are built. This method is clear, uncomplicated and lucid, which offers a more convenient way to analyze mechanism’s kinematics characteristic so that it is suitable for project designs. By means of resolving the vehicle abnormal vibration, it can prove that the model in this paper is correct, and it draws the conclusion about the main reason for abnormal vibration induce by the angle ? between drive shaft and driven shaft. The driven shaft’s periodicity on rotate speed, angle acceleration and torque find by matlab simulation, which breadth increasing with angle? . So it provides theory for reasonable disposal and reliability analysis on transmission shaft.A method of vector analysis is presented, which is used to building the rear-axle flouncing model. This method is clear, uncomplicated and lucid. Through comparing with the traditional diagram of transmission shaft, the result of the rear-axle flouncing model is accurate, and it can completely replace the traditional diagram of transmission shaft. The Matlab software is used to making the simulation and the variation curve of transmission shaft’s length and angle is gained during rear axle flouncing, which will provide theoretic reference for the disposal of the transmission shaft, and which is more practical in engineering.On the basis of the rear-axle flouncing, the kinematics emulational characteristics of the transmission shaft are done on the different pavement. The conclusion can be drawn as follow: 1) Root mean square will increase with increasing of transmission shaft initial angle, 5 ~ 7°in the angle between the root mean square value of the trend slowing down;2)For the influence of root mean square value,transmission shaft initial angle changes more rapidly than amplitude of pavement., thus affecting the acceleration root mean square value change in the major factor in transmission shaft initial angle. So it provides theoretical basis for the design of transmission shaft.3. Research on Transmission Shaft’s Optimal MatchingFirstly,the transmission shaft’s centrifugal force is analyzed, and the vehicle vibration model including the transmission shaft’s centrifugal force is built.Secondly,multiple parameters of the transmission shaft are analyzed and researched on the basis of the improved vibration model by means of orthogonal test,which will provide the theoretical basis for the reasonable matching of the transmission shaft’s parameters.Thirdly,It can be drawn from the orthogonal test that assembly errors and ratio of rear axle are important factors for influencing test index from vibration level’s point of view, and that errors , ratio of rear axle and carrying-capacity of saddle are important factors for influencing test index from comfort performance’s point of view.4. Research on Fault Vehicle’s Optimal MatchingOn the basis of genetic algorithm, optimization analysis of the fault vehicle’s suspension has been done, and it will provide the reference for optimal matching of suspension. By optimal matching of the fault vehicle’s suspension, it can be drawn the conclusion that suspension stiffness is so large that vehicle vibration aggravates. With fixed suspension stiffness of the fault vehicle, by optimal matching of saddle’s carrying-capacity, it can decrease the fault vehicle’s vibration. By means of orthogonal test, It can be found that carrying-capacity of saddle is fluctuant and important factors for influencing the fault vehicle’s vibration. The original design carrying-capacity of saddle is 10 tons, but its corresponding root mean square is too large from curve, so design value is unreasonable. It is a suggestion that the design carrying-capacity of saddle should be 11 tons.With fixed suspension stiffness of the fault vehicle, by optimal matching of ratio of rear axle and distance of towing attachment, it can decrease the fault vehicle’s vibration. By means of orthogonal test, multiple parameters of the transmission shaft are analyzed and researched, which will provide some solutions and methods for the improvement vibration level of the fault vehicle. Through the vehicle road test, it verifies the correctness of the simulation results, and the improved vehicle vibrates perfectly.更多还原