行波型超声波电机摩擦特性的实验研究

Experimental Investigation on Friction Characteristics of Ultrasonic Motor

超声波电机是通过逆压电效应产生高频振动并通过摩擦实现驱动的电机,其定转子摩擦接触面的高频、微幅的行波振动有其特殊性,跟以往的摩擦接触显著不同,并对电机的换能效率、电机寿命和摩擦材料的选择等都有影响.本文建立了超声波电机定转子接触面摩擦系数测量装置,通过试验比较了摩擦接触面在常规、定子驻波振动以及行波振动下的动态摩擦系数,分析了定子相对转速(速度)、预紧力以及温度对定转子接触面摩擦系数的影响.根据摩擦二项式和电机定转子表面弹塑性接触状态对摩擦系数与预紧力等的对应关系进行了说明,分析了驻波振动和行波振动的超声减摩效果以及温度对摩擦系数的影响,确定了适合行波型超声波电机的摩擦系数计算模型.超声波电机的驱动摩擦特性是1项基础性工作,有助于行波形超声波电机设计、建模和驱动控制等.

Ultrasonic motor is an unconventional motor driven by frictional force and high frequency vibration based on the principle of inverse piezoelectric effect.The high frequency vibration and minor amplitude between the stator and rotor have its own characteristics at friction interface,which is different from the traditional interface.The characteristics have significant effect on conversion efficiency,motor＇s lifetime and the choice of frictional material.This paper presented the dynamic friction coefficient in normal,standing wave and the traveling wave measured by self-manufactured experiment structure.The influences of the relative speed,preload and temperature＇s impact on friction coefficient between the stator and rotor were analyzed.The relationship between friction coefficient and preload was explained from friction binomial and elastoplasticity contact state of the interface.The paper also explained the effect of friction reduction in the presence of ultrasonic vibrations both from standing wave and traveling wave.The impact of temperature on friction coefficient was also tested.Finally,this paper revealed a friction model for ultrasonic motor.The friction reduction for ultrasonic motor was a foundmental work,which was useful for design,modeling and controlling of ultrasonic motor.