多楔带动态特性及带-轮间摩擦系数的测试分析

Measurement of Dynamic Properties for Serpentine Belt and Friction Coefficient Between Belt and Pulley

多楔带的刚度、阻尼系数和带-轮间的摩擦系数是单根多楔带驱动系统动态特性计算分析的重要参数。以汽车用6PK型多楔带为研究对象,测量了带的纵向静态和动态特性、弯曲刚度和带-轮间的摩擦系数。分析了带长、初始张力、激振振幅和激励频率对带的纵向动刚度和阻尼系数特性的影响,建立了表征带的纵向动刚度和阻尼系数与带长、初始张力、激振振幅和激励频率关系的多项式模型和指数函数模型。采用力锤激振的方法,测试带横向方向共振频率,通过最小二乘方法计算得到带的弯曲刚度,并分析了带的长度对带弯曲刚度的影响。测试并研究带的初始张力、带-轮间的包角和轮的转速对带-轮间摩擦系数的影响,得到汽车发动机前端附件驱动系统中带-轮间摩擦系数的取值范围。

The stiffness and damping of serpentine belt and the friction coefficient between belt and pulley,are important parameters for designing a serpentine belt-pulley accessory drive system and calculating its dynamic characteristics.Experimental methods and data processing techniques for measuring belt longitudinal static stiffness,longitudinal dynamic stiffness and damping coefficient,bending rigidity,and friction coefficient between belt and pulley are illustrated.A serpentine belt with six ribs and a K-rib section(6PK)is taken as the test belt in the experiments.The influences of pre-tension,belt length,excitation amplitude and frequency on the longitudinal dynamic stiffness and damping for a belt are measured and discussed.Tested results show that the influences of pre-tension,belt length,excitation amplitude and frequency on the dynamic stiffness are significant,and the damping coefficient of belt is frequency-dependent.Two models of polynomial function and exponential function are presented for modeling belt longitudinal dynamic stiffness and damping coefficient,respectively.The resonant frequency of transverse vibration for belt is measured by shock hammer method,and the bending stiffness of belt is calculated by least-squares method.Then,the influences of the belt length on the belt bending stiffness are measured and analyzed.The influences of the pre-tension of belt,wrap angle between belt and pulley and rotational velocity of pulley on the friction coefficient are measured and analyzed,and the ranges of the friction coefficient are obtained.