A study on the rotary-type ultrasonic motor using a longitudinal–torsional vibration converter

In this paper a rotary-type ultrasonic motor, which has simple structure and high torque, was studied. For amplifying the longitudinal vibration of piezoelectric ceramic, the Langevin-type vibrator was used. A stator of the motor was constructed by attaching the longitudinal–torsional vibration converter, which has inclined slits on the top of the Langevin-type vibrator. A rotor was pressed by a spring on the driving surface of the stator. The stator operated between 42.8 and 43 kHz when input voltage was 60 Vrms. Revolution speed and torque were increased when the input voltage was increased. Revolution speed and torque were 33.3 rpm and 160.1 mN m at input voltage of 65 Vrms. Revolution speed was lineally decreased when the load was increased. Maximum revolution speed was 33.3 rpm at frequency of 42.9 kHz with 65 Vrms. And the maximum efficiency of 1.14% was obtained at this condition with preload of 540 gf.