Composite ultrasonic motors using a piezoelectric disc and an elastic body of "windmill" type

This paper deals with a new piezoelectric ultrasonic motor operated by single-phase AC. The ultrasonic motor of windmill type using a piezoelectric ceramic and a metal elastic body was fabricated. To prepare the piezoelectric ceramics vibrator, 0.05PMN-0.95PZT composition was mixed with 0.7wt% MnO₂. Dielectric loss, the electromechanical coupling factor of radial mode and mechanical quality factor were 0.2%, 62.8% and 820, respectively. The slotted metal elastic bodies made from brass sheet were machined at various thickness of 0.15, 0.20, 0.25, 0.30mm, and slots of the elastic body were 2,3,4,6, respectively. No-load revolution speed increases with increasing applied voltage, and it increases with decreasing the thickness of the elastic body. The revolution speed of the ultrasonic motor is 510rpm under an applied voltage of 100 V_max.