新型行波压电电动机的结构研究及理论分析

STRUCTURE STUDY AND THEORETICAL ANALYSIS ON NEW TYPE TRAVELING WAVE PIEZOELECTRIC MOTOR

环型和圆盘型行波压电电动机小直径条件下,输出性能逐渐失去低速大力矩的特点。由于结构限制,其定转子的动态点接触导致电动机运转不平稳、磨损大和驱动力矩小等不足。针对这些不足提出一种新型行波柱面驱动压电电动机,将传统的点接触改进成现在的线接触,即环型或圆盘型定子改进成圆柱型定子。阐述了行波压电电动机的运行机理以及电动机驱动系统原理。通过对压电电动机定子结构的振动理论分析,证明此新型结构电动机符合一般压电电动机形成驱动及正常工作的基本条件。利用ANSYS有限元软件分析电动机定子的振动模态, 给出选取振动模态的理论依据。制作了直径为20 mm的柱面驱动压电电动机,并对其输出特性进行测试,得到测试结果为输出力矩／质量比是0．426。

Traveling wave ring-type or disc-type piezoelectric motor tends to lose the characteristic of large torque with low speed as its diameter is small. Plus its structural restriction, the dynamic point contact between the stator and the rotor leads to many disadvantages such as rough running, serious abrasion, low driving torque, etc. To make up for these shortages a new type traveling wave piezoelectric motor with cylinder stator is presented, which features the cylindrical stator and the line contact instead of the traditional ring or disc type and the point contact. The operation mechanism of the new type traveling wave piezoelectric motor and the principle of its driving system are also explained. The theoretical analysis of the stator proves that the motor with this new structure can well meet the demands for driving and operating. Using the finite element software ANSYS for the analysis of the vibration mode of the stator, a theoretical principle in selecting the vibration mode of the stator is offered. Finally a cylinder-driving piezoelectric motor with a diameter 20 mm is manufactured, and the test on its output characteristics is carried out. Result of the test shows that the ratio of output torque/mass is 0.426.