Design of Miniature Cylindrical Ultrasonic Motor with Longitudinal Bending Compound Excitation

In order to improve the mechanical performance of ultrasonic motor, a miniature patch cylindrical traveling wave ultrasonic motor using longitudinal bending composite excitation is proposed. The motor is composed of a cylinder and a longitudinal-bending transducer located on the lateral wall of the cylinder. The transducer is made up of a pair of bending vibration piezoelectric ceramic plates, a pair of longitudinal vibration piezoelectric ceramic plates and a rectangular aluminum piece whose front end is the amplitude transformer. The motor is designed and simulated using finite element method based on the analysis of the working principle of the motor, which realizes frequency degeneracy of the two basic vibration modes of the motor. The vibration characteristics are tested. The test results well agree with the results of finite element method, and show that longitudinal vibration mode, bending vibration mode and cylindrical bending vibration mode match well.