Structure Design And Model Research Of A Novel Linear Type Ultrasonic Motor

Ultrasonic motor is a new kind of driving device, which uses the converse piezoelectric effect of piezoelectric ceramics to convert the electrical energy into the mechanical vibration. As an important branch of ultrasonic motor, linear type ultrasonic motor is widely applied in aerospace, medical, military and other fields due to its inherent characteristics of simple structure, flexible design and positioning precision, miniaturization. And it has attached wide interests of researchers. At present, the researches on linear type ultrasonic motor mostly focus on multi-modes linear ultrasonic, which using multi-modes as the working mode. The disadvantage of this kind of motor is the frequency tuning of the modals, it usually needs to tune the resonance frequencies of the modals to consistent or very close to each other. This will lead to a higher requirement of the size of the stator structure, poor design flexibility, installation, and design will more complex and production costs will increase. Besides, the multi-modes linear ultrasonic motor are strict with the phases, thus this kind of motor needs more drive circuit to control each mode, the design of drive circuit is more complex.This paper proposes a novel linear type ultrasonic motor. The research contents of the thesis include three parts. The first part preliminary designs the basic structure of this new kind of ultrasonic motor. The finite element method is used for modeling the stator. Based on this model, modal characteristics, harmonic response and transient response of the stator is analyzed. And then the work modal and frequency of the stator were determined. The second part, firstly, introduces the operation mechanism of the stator. According to the first axial order vibration theory of stick and the fourth bending order vibration of beam, the vibration equation of the driven are built. The elliptical trajectory of the driven is deduced in theory. And, finally, the effect of voltage amplitude and phase on elliptical trajectory of the driven is analyzed. The third part mainly analyzes the contact friction between the stator and the slider. Biased on the Coulomb’s Law and impulse law, force transfer model of the contact friction between the stator and the slider is built. And the features (include the output force, linear speed, the power and efficiency of the contact) of the contact is obtained. Finally, a comprehensive analysis on the effect of the pre-press, voltage amplitude, voltage frequency on motor output characteristics was conducted. Those provide the theory basis for the research on single linear ultrasonic motor both on optimal design and on performance analysis.