CVT金属带轴向偏移及控制方法研究

发布时间：2018-11-17 21:43

【摘要】：金属带式无级变速器(CVT)是汽车的理想传动装置,金属带和主、从动带轮作为CVT的关键部件,承担着传递转矩与动力的作用。目前市场上使用的CVT产品均为直母线带轮,由其特定的变速方式所决定,在工作过程中金属带的中心线必然会发生轴向偏移。金属带的轴向偏移使得带与带轮间受力状况更加复杂,破坏摩擦片与带轮间的弹流润滑,从而影响CVT的传动性能与效率。本文围绕CVT金属带的轴向偏移进行研究,完成了以下的工作:(1)分析了CVT中金属带与带轮的结构特点,阐述了金属带轴向偏移的产生机理,推导了CVT传动的基本几何关系,在此基础上推导了摩擦片间推力与钢带环间张力的计算公式,为后续研究提供了理论基础。(2)建立了以带轮的初始装配尺寸来表征偏移量的计算模型,在此基础上,引入了带轮的变形,研究了带轮楔角、带轮轴向变形和带轮中心距对金属带偏移的影响。(3)分析了金属带轴向偏移时摩擦片的受力情况,应用有限元软件对其进行了应力分析,并与未偏移时的摩擦片进行了对比;推导了由于金属带的偏移而造成的功率损失的计算公式。分析了两种控制金属带轴向偏移方法的原理和不足,提出了一种以轴向偏移量平均值最小、通过调整带轮初始装配尺寸确保金属带无偏移时的速比的优化方法。(4)对文中优化计算得到的带轮初始装配尺寸进行检验,首先进行了CVT金属带轴向偏移试验系统的设计,分为三大模块进行了详细的设计。然后以RD-CVT为测试对象,在三种典型工况下进行了试验,结果表明系统的传递效率在文中计算得到的最优带轮初始装配尺寸时达到最大值,即金属带的轴向偏移对CVT传动性能的影响最小,因此确定的最优带轮初始装配尺寸是可行的。
[Abstract]:Metal belt stepless transmission (CVT) is the ideal transmission device of automobile. Metal belt and main driving belt wheel, as the key parts of CVT, play the role of transmitting torque and power. At present, the CVT products used in the market are all straight busbar pulleys, which are determined by its specific speed changing mode. In the working process, the center line of the metal belt will inevitably have an axial shift. The axial migration of the metal belt makes the mechanical condition between the belt and the belt wheel more complicated, which destroys the elastohydrodynamic lubrication between the friction sheet and the belt wheel, thus affecting the transmission performance and efficiency of CVT. In this paper, the axial migration of CVT metal belt is studied, and the following works are accomplished: (1) the structural characteristics of metal belt and belt wheel in CVT are analyzed, the mechanism of axial migration of metal belt is expounded, and the basic geometric relation of CVT transmission is deduced. On this basis, the formula for calculating the thrust between friction plates and the tension between the rings of steel strips is derived, which provides a theoretical basis for further research. (2) the calculation model of the offset represented by the initial assembly size of the belt wheel is established. In this paper, the deformation of belt wheel is introduced, and the influence of wedge angle, axial deformation of belt wheel and center distance of belt wheel on the migration of metal belt is studied. (3) the force of friction sheet is analyzed when the metal belt is offset in axial direction. The finite element software is used to analyze the stress, and the results are compared with the friction plates without deviation. The formula of power loss caused by the deviation of metal strip is derived. This paper analyzes the principle and deficiency of two methods to control the axial migration of metal band, and puts forward a method to minimize the average value of axial migration. By adjusting the initial assembly size of the belt wheel to ensure the speed ratio of the metal belt without deviation. (4) to test the initial assembly size of the belt wheel obtained by the optimization calculation in this paper, the axial offset test system of the CVT metal belt is designed firstly. It is divided into three modules to carry on the detailed design. Then, taking RD-CVT as the test object, three typical conditions are tested. The results show that the transfer efficiency of the system reaches the maximum when the initial assembly size of the optimal belt wheel is calculated in this paper. That is to say the axial deviation of metal belt has the least influence on the transmission performance of CVT so it is feasible to determine the optimal initial assembly size of belt wheel.
【学位授予单位】：湘潭大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U463.221

【相似文献】