CVT动态载荷传递及轴承孔进行性损伤机理研究

Progressive damage of bearing bore is one of the key common problems affecting the reliability of CVT, which is manifested as eccentric wear of bearing bore caused by creep of bearing outer ring, which gradually accumulates and evolves over time, and its global mechanism is still unclear. The damage can cause chain direction deflection, aggravate wear, seriously reduce life of CVT. Therefore, this project proposed the research idea of bearing bore damage based on the dynamic characteristics of the CVT system. By theoretical analysis, virtual simulation and experiment, the dynamic model of the CVT system was constructed including the coupling mechanism of chain drive characteristics, hydraulic actuator and CVT multi-parts. The dynamic load transfer path of multi-source excitation and its influence mechanism on bearing bore damage are studied. Virtual test method was used to analyze the influence of design parameters and running parameters on the dynamic load of bearing bore and outer ring creep；The sensitivity of multiple parameters to bearing bore damage was studied by intelligent parameter identification method. Take bearing bore damage degree as the iterative parameter, the evolution process of bearing bore damage under multiple working conditions is analyzed and parameterized described. Through this project, the mechanism of bearing bore damage can be clarified, and the parametric description of the evolution process of bearing bore damage can be obtained. The theoretical analysis method of bearing bore damage can be formed, which is of great significance for improving CVT dynamic theory and promoting industrial technology upgrading.

轴承孔进行性损伤是影响CVT可靠性的关键共性问题之一，表现为轴承外圈蠕变引起的轴承孔偏磨，随时间呈进行性累积演变，全局动力学机理尚未明确。该损伤引起链条偏斜运行、并加剧其磨损，严重降低CVT使用寿命。为此，本项目提出基于CVT全局系统动力学特性的轴承孔损伤问题研究思路，理论分析、虚拟仿真与实验相结合，从链传动特性与液压作动装置、CVT多部件的耦合机制出发，构建CVT全局系统动力学模型；研究多源激励动态载荷传递路径及对轴承孔损伤的影响机理；采用虚拟试验法，分析设计参数、运行参数对轴承孔动态载荷、外圈蠕变的影响，并采用智能参数辨识法研究多参数对轴承孔损伤的敏感度；以轴承孔损伤度为迭代参数，分析车辆多工况下轴承孔损伤演化过程并以参数化描述。通过本项目，可明确轴承孔损伤机理、得到轴承孔损伤演化过程的参数化描述，形成轴承孔损伤问题的理论分析方法，对提升CVT动力学理论、促进产业技术升级具有重要意义。

本项目以合作研发单位“柳州上汽汽车变速器有限公司柳东分公司”的CVT8型号CVT为原型，构建了链式CVT机械、液压耦合的系统动力学模型，轴承支撑点处的振动信号的时、频域特性的计算结果与测试结果表现出了较好的一致性；针对链式CVT液压控制系统的振动特性，揭示了液压系统关键设计参数对压力振动的影响机理，并对液压系统结构参数开展了优化设计；采用数值计算方式分析了液压系统振动激励、发动机扭矩转速输入激励条件下，链式CVT支撑轴承处的动态载荷状态，研究了销轴设计参数对动态载荷的影响；结合测试数据，明确了轴承磨损的进行性发展过程曲线，并揭示了轴承部分关键参数对其磨损过程的影响。分析结论被应用于CVT8型产品，有效地减低了CVT磨损程度，提高了CVT的使用寿命。在项目资助下，本项目执行过程中授权国际发明专利2项、中国发明专利1项，并完成知识产权转化1项。培养研究生2名。目前，本项目仍有部分研究内容尚在进行中。