【作者】 李利平；

【导师】 鲁寨军；

【作者基本信息】 中南大学 ， 载运工具运用工程， 2022， 博士

【摘要】 摩擦离合器作为汽车传动系统中的主要组成部分,承担着中断和传递动力的重要作用。其性能好坏,直接影响了汽车的平稳起步、车身的振动噪声以及驾驶员的操控感受。为了消除汽车行驶过程中由于摩擦离合器传动系统扭振带来的车身振动与噪声问题,探索离合器及其操纵系统的匹配设计方法,指导离合器及其操纵系统的正向设计开发,本文对离合器传动系统的动态特性进行研究,建立相关模型,开展理论研究和试验分析。论文的主要研究工作有:(1)建立了离合器轴向分离特性解析模型以及有限元计算模型,并对其进行了仿真计算,得到离合器膜片弹簧、从动盘波形片、传动片以及离合器的轴向分离力和分离位移关系;开展了离合器轴向分离特性台架试验,验证了离合器轴向分离有限元计算模型的正确;分析了离合器轴向分离特性的影响因素,研究了膜片弹簧参数、波形片参数、传动片厚度、摩擦片磨损和温升等因素对离合器最大分离力、最大分离位移和分离力峰谷差值的影响规律。(2)建立了汽车摩擦离合器传动系统五自由度动力学模型,综合考虑了离合器的摩擦特性、扭转特性、阻尼特性以及变速器齿轮的时变刚度等非线性因素的影响;对建立的动力学模型进行了动态响应计算,从时域和频域两个方面分析了离合器接合时车身抖动现象及变速器齿轮敲击现象产生的机理;开展了实车测试,验证了五自由度动力学模型和计算方法的正确性和有效性;阐述了表征离合器接合抖动、变速器齿轮敲击和离合器振动衰减的评价指标,分析了影响离合器接合时车身抖动和变速器齿轮敲击现象的因素,研究了离合器关键设计参数对离合器传动系统动态特性的影响。(3)建立了离合器操纵系统的力学模型,模型中考虑了助力机构的助力特性和动态特性;基于该模型对样车离合器操纵系统的踏板力-位移进行了计算,并实车测试了该样车离合器操纵踏板力-位移特性,验证了所建离合器操纵系统数学模型的正确性;分析了离合器操纵舒适性的影响因素,研究了离合器操纵系统关键参数对踏板力峰值和踏板行程的影响。(4)基于多目标优化方法对离合器传动系统动态特性进行了改善,实现了离合器及其操纵系统的匹配设计。基于最优拉丁超立方抽样和响应面近似方法建立了离合器动态特性优化代理模型,利用方差分析对代理模型进行了误差和精度分析,基于遗传算法进行了寻优计算,输出了最优结果,实现了离合器传动系统动态特性优化;基于优化结果,改进了一款样车离合器,并开展了试验,验证了该匹配设计方法及求解过程的正确性。改进后的样车离合器传动系统动态特性有了很大的提升:变速器处垂向振动加速度降低了32%,驾驶室的噪音降低了32.2%,离合器操纵特性满足设计标准。本文的建模计算与分析方法对离合器及其操纵系统的正向开发设计具有一定的指导意义。图93幅,表50个,参考文献159篇更多还原

【Abstract】 As one main component in the automobile driveline,friction clutch plays an important role in interrupting and transmitting power from the engine to the driveline.Its performance directly affects the smooth starting of the car,the vibration and noise of the car body and the driver’s handling feeling.In order to eliminate the vehicle body vibration and noise caused by the torsional vibration of the driveline during vehicle driving,to explorer the matching design method of the clutch and its operation system,and to guide the forward development of the clutch and its operation system,the modeling method for dynamic characteristic of driveline with friction clutch and for clutch operation system is studied,and the relevant models are proposed also the theoretical research and experimental analysis are carried out.The major studies can be summarized as follow:(1)The theoretical calculation model and finite element calculation model of the axial separation characteristics of the clutch are established,and the simulation calculation is carried out.The relationship between the axial separation force and separation displacement of the clutch diaphragm spring,the driven plate corrugated plate,the transmission plate and the clutch is obtained.The bench test of clutch axial separation characteristics is carried out to verify the correctness of the finite element calculation model of clutch axial separation.The factors affecting the axial separation characteristics of the clutch are analyzed,and the effects of diaphragm spring parameters,wave plate parameters,transmission plate thickness,friction plate wear and temperature rise on the maximum separation force,maximum separation displacement and peak valley difference of separation force of the clutch are studied.(2)A five degree of freedom dynamic model of the driveline with friction clutch is established.The effects of nonlinear factors such as friction characteristics of clutch,torsional characteristics and damping characteristics of torsional damper and time-varying stiffness of transmission gear are considered in the model.The clutch friction torque model,the compression force model and the multi-stage stiffness and damping model of torsional shock absorber are studied.The dynamic response of the established dynamic model is calculated,and the mechanism of body shaking and transmission gear knocking when the clutch is engaged is analyzed in time domain and frequency domain.The real vehicle test is carried out to verify the correctness and effectiveness of the five degree of freedom dynamic model.The evaluation indexes are expounded to characterize the clutch engagement jitter,the transmission gear knocking and the clutch vibration attenuation.The factors affecting the body shaking and transmission gear knocking phenomenon when the clutch is engaged are analyzed.The influence of key design parameters of clutch on the dynamic characteristics of clutch transmission system are studied.(3)A mathematical model of the clutch operation system is established,and the power-assist characteristics and dynamic characteristics of the power-assist mechanism are considered in the model.Based on the model,the pedal force-displacement of the clutch operation system of the sample vehicle is calculated,and the force-displacement characteristics of the clutch pedal of the sample vehicle are tested,which verifies the correctness of the mathematical model of the clutch operation system.The influencing factors of clutch handling comfort are analyzed,and the effects of key parameters of power assisted mechanism of control system on pedal force peak and pedal stroke are studied.(4)Based on the multi-objective optimization method to improve the dynamic characteristics of the clutch transmission system,the matching design of the clutch and its manipulation system is realized.An optimized proxy model for clutch dynamic characteristics is developed based on optimal Latin hypercube sampling and esponse surface approximation methods,and the error and accuracy of the proxy model are analyzed using analysis of variance.The optimal combination of parameters is obtained by using genetic algorithm to optimize the dynamic characteristics of the clutch transmission system.Based on the optimization results,a prototype clutch is improved and tests are carried out to verify the correctness of the matching design method.The dynamic characteristics of the clutch transmission system of the improved sample vehicle have been greatly improved: the vertical vibration acceleration at the transmission has been reduced by 32%,the noise in the cab has been reduced by 32.2%,and the clutch control characteristics meet the design standards.The modeling and analysis method in this dissertation has certain guiding significance for the forward development and design of clutch and its operation system.93 figures,50 tables,159 references更多还原