滑移控制模式下金属带式无级变速器油膜牵引及磨损特性研究

Strengthening the basic research of the metal belt continuously variable transmission (CVT) is an important guarantee to master the core technology of CVT, to strive the right of shaping the future of automatic transmission, and to promote the technological progress of China's vehicle drive technology. The proposal focuses some key technical issue such as how to improve the transmission efficiency and reliability of the metal belt CVT under controlled slip conditions. Aiming at the characteristics of non-continuous contact, multi-direction movement and multi-boundary conditions of the pulley and belt, the friction traction equation of the metal belt will be established. The friction models between the blocks and pulley, the blocks and metal rings, and each of the metal rings will be also established. The rheological constitutive relationship of lubricant under the conditions of high-pressure, high-speed will be built based on the experiment results, while the conditions of the formation of oil film traction will be also studied. The torque, speed, running radius and other movement parameters will be monitored, the effects of the slip rate, friction coefficient and operating parameters on the transmission efficiency and reliability will be investigated. Applying the tribo-chemical theory, the lubrication and wear mechanism on the interface of CVT will be verified. What's more, the patterns and performance specifications of CVT lubricant formulations will be formed. At last, the relationship of "the tribological properties - slip rate - transmission efficiency" will be revealed, and the slip transient dynamic model for metal belt CVT will be built. We hope to provide a theoretical basis for developing a high efficiency, high reliability, long-life CVT transmission technology through the research work.

加强金属带式无级变速器的基础研究，是掌握其核心技术，争取轿车自动变速器话语权，促进我国车辆传动技术进步的重要保证。本项目以金属带式无级变速器在滑移控制条件下提高传动效率和可靠性的关键技术问题为研究对象，针对带轮与摩擦片间非连续接触、多向、多边界条件的特点，建立金属带摩擦传动方程，以及摩擦片与带轮间、摩擦片与金属环间、金属环与金属环之间的摩擦模型；通过实验构建润滑剂高压、高转速条件下的流变学本构关系，研究形成油膜牵引的条件；实验监测扭矩、转速、工作半径等参数，研究滑移率、摩擦因数和运行参数对传动效率和可靠性的影响；结合摩擦化学理论，探明CVT运动界面润滑、磨损机理，形成CVT润滑剂配方模式和性能规范；揭示"摩擦学特性-滑移率-传动效率"关系，创建金属带式CVT滑移瞬态动力学模型，为发展高效率、高可靠性、长寿命CVT传动技术提供理论基础。

本项目主要开展了金属带式无级变速器（CVT）在滑移控制模式下的运动学、瞬态动力学和传动效率等研究。.根据金属片、带环及带轮三者之间力与运动的传递关系，建立了低速比工况下金属带紧边与松边的力学模型，揭示了主动带轮出现打滑现象的条件；获得了低速比工况下主动带轮工作半径与速比的显性函数关系式，得到了紧边金属片推挤力、带环有效张力与速比、摩擦系数、输入扭矩、离心力等因素之间的连续解析关系，并逐个分析了这些因素对紧边金属片推挤力与带环有效张力的影响；推导了传递最大有效转矩时所需最小轴向夹紧力的表达式，结合主动轮工作半径与速比的关系，分析了速比、输入扭矩对所需最小轴向夹紧力的影响。.将建立的金属带传动的运动学模型和CVT金属带摩擦功率损失模型相结合，得出了金属片与带轮间的径向摩擦功率损失、切向摩擦功率损失、金属片鞍面与最内层带环的摩擦功率损失的影响因素。结果表明，金属片与带轮间的摩擦是造成金属带组件功率损失的主要原因，在低速比工况下总的摩擦功率损失随着速比的增大而增大。.综合考虑了金属带传动中轴向偏斜、金属片间隙、多向运动、非连续接触及滑移等对金属带与带轮受力的影响，分析了滑移控制模式下金属带式CVT瞬态动力学特性。建立了主动带轮静弧角度计算方法，研究了滑移产生机理及滑移对转矩传递的影响；建立了CVT摩擦传动模型，分析了带轮变形、金属带运行轨迹对金属片推力以及带环张力的影响、滑移率对金属片推力的影响、滑移率对传动效率的影响等；研究确定了滑移率估测方法，“金属带式无级变速器滑移率测试台”获发明专利授权。.本项目研究成果在湖南江麓容大车辆传动股份有限公司得到成功的应用，为该公司与德国BOSCH公司的国际合作打下了坚实的基础，并解决了带轮表面处理工艺评价和行星齿轮箱抗冲击柔性连接设计等工程问题，相关研究成果获湖南省科技进步三等奖，双方合作开发的新一代车辆无级变速箱已成功推向市场，提升了国产汽车变速箱的竞争力。

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