A Novel Rotary Ultrasonic Motor Using the Longitudinal Vibration Mode

A novel rotary ultrasonic motor using only the longitudinal vibration mode was proposed in this paper, which avoided the frequency degeneration of multi-modal coupling ultrasonic motors. The structure of the ultrasonic motor was designed; the ultrasonic motor was mainly made up of two longitudinal transducers, a rotor, a basement and two mounting bases for adjusting the relative position between longitudinal transducers and the rotor. Two transducers were arranged symmetrically about the axis of the rotor, which drove the rotor under the frictional forces. The operating principle was discussed. The modal characteristics of the longitudinal transducer were investigated by the Finite Element Method (FEM). Two longitudinal transducers have the same structures and vibration modes, first order longitudinal vibration is used for drive; the ultrasonic motor is simple in structure and flexible in design, so it is suitable for industrial production. Furthermore, as the transducers' sizes and relative position between the transducers and the rotor are easy to vary, the mechanical characteristics of the proposed motor can be changed flexibly. The experimental rotary speed of the proposed ultrasonic motor at the voltage of 300 Vp-p is 350 revolutions; and the maximum torque is 186 N.mm.