AN ANALYSIS OF A NONCONTACT ULTRASONIC MOTOR WITH AN ULTRASONICALLY LEVITATED ROTOR

The authors have proposed a noncontact ultrasonic motor whose rotor is levitated ultrasonically and revolved at a very high speed. This pape r presents the theoretical calculations and the experimental discussio ns to improve the revolution characteristics and the stability of the rotor axial position. Being based on the theory of near-boundary acous tic streaming, a theoretical model for the calculation is developed. F ollowing this, the effects of the velocity and the mode number of the stator vibration, the driving frequency and the width of the gap betwe en the stator and the rotor are estimated numerically. Ten motors with different dimensions are made to verify the calculated results. The n umerical and experimental results give us a lot of useful guidelines f or designing this motor. (C) 1997 Elsevier Science B.V.