Design of a bending vibrations hybrid type ultrasonic motor with a bonded-type structure

A bending vibrations hybrid type ultrasonic motor with a bonded-type structure is proposed and designed in this work. Four pieces of PZT plates are bonded on a metal beam to form the proposed motor. In this design, elliptical movements of the driving feet, the significant motion to realize the actuating of a rotor, is produced by the superimposing of two first bending vibrations orthogonal in space. The structural parameters' sensitivities of the bending resonance frequency and the electromechanical coupling factor are calculated and discussed by modal analysis and harmonic analysis respectively. The most sensitive parameters are obtained. Then, the vibration characteristic of the proposed motor is investigated by transient analysis; another ultrasonic motor with the same length but no horns is also calculated to give a comparison. Different with previous motor, the proposed one drive the runner by two transversal displacements of the driving tip; this new actuating mode has merits of higher resonance frequency, larger vibration amplitude and velocity, better movement trajectory uniformity and shorter response time. The study results can guide the fabrication of linear or rotary ultrasonic motor with small size.