柔性转子对行波超声波电动机性能的影响

Effect of Flexible Rotor on Performance of Traveling Wave Type Ultrasonic Motor

提出旋转型行波超声波电动机中柔性转子的明确定义,指出柔性转子属于做大范围运动的弹性圆板的动力学范畴,得到了柔性转子上任意点的运动描述。利用Lagrange方程,得到柔性转子的刚柔耦合的动力学模型,并将其与基于柔性转子的接触界面模型、定子的半解析动力学模型有机地融合在一起,得到了整个电动机的动力学描述。通过分析实例,表明当把转子作为柔性体来考虑时,定、转子的接触界面变得复杂和不对称.由此解释了试验中发现的适当转子阻尼可以改善电动机性能的现象。进一步分析和阐释了柔性转子通过自身的弹性变形,减少界面上定、转子之间的径向磨损并提高电动机输出效率的机理,得到了试验的验证,为柔性转子的结构设计提供了理论依据。

First the definition of flexible rotor of traveling wave type rotary ultrasonic motor （TRUM） is given. It is pointed out that the flexible rotor can be classified in the range of elastic annular plate with large overall motion. And the kinematical equation of flexible rotor is derived. Then the rigid-flexible coupling dynamic model of flexible rotor is obtained by Lagrange equation. So the complete model of TRUM is derived by the integration of the contact model based on flexible rotor, stator＇s semi-analytical model and flexible rotor model. The analysis examples show that the complicated contact mechanism with asymmetry occurs at the inter- face between the stator and flexible rotor. The analyses explain how the appropriate damp of rotor can lead to thegood performance of motor. Moreover the proper flexible rotor is proved to improve the motor＇s output efficiency by decrease of the friction in the radial direction at the interface. Finally the results of simulation are found to be in good agreement with those of experiments, so the proposed model provides the theoretical foundation for the design of the flexible rotor.