液体媒质超声波电机转子稳定性理论和实验研究

Theoretical and Experimental Study on Rotor Stability of Ultrasonic Motor Driving Fluid Directly

液体媒质超声波电机定、转子不直接接触,利用液体媒质驱动转子旋转,是超声波电机新的研究方向。在液体媒质超声波电机中,转子的稳定性是一个关键问题。该文利用有限元分析软件CAPA和ANSYS,分析了在受到电压激励时电机内液体媒质的声流速分布。通过仿真发现,液体媒质同时存在切向流动和径向流动,是一种紊流,速度的大小和方向与激励电压和液体参数密切相关。切向流动推动转子旋转,而径向流动作用在转子上,引起了转子不稳定。为了分析方便,假设转子轴不固定,径向流动对转子的作用可通过弹簧和质量块构成的单自由度系统模拟,这样转子的稳定性可利用转子的振动频率衡量。通过实验研究了电机激励电压、转子厚度、液体媒质的高度及类型与转子振动频率的关系,为提高转子稳定性、优化电机设计提供了参考依据。

The ultrasonic motor driving fluid directly is a new type of non-contact ultrasonic motor. The rotor does not contact with the stator and is driven by fluid medium. The rotor stability is a key factor to its application and control. By means of finite element analysis, the velocity distribution of acoustic streaming was analyzed. The simulation results show that, radial velocity and tangential velocity occur at the same time, whose amplitude and direction are influenced by the exciting voltage and parameters of the fluid. The radial velocity acting on the rotor causes the rotor unstable. To analyze easily, it is assumed that the rotor axial was not fixed, thus the influence of the radial velocity on the rotor can be simulated by a system including spring and mass, and the rotor stability can be weighed through the vibration frequency of the rotor. By this model and relevant experiments, factors that affect the stability of the rotor such as the rotor＇s thickness, the exciting voltage, the fluid＇s height and type are investigated and useful guidelines for design and application are obtained.