A small size ultrasonic motor

A small size ultrasonic motor has been developed which exploits the traveling waves produced by bending vibration. The motor is composed of a vibrating disk stator and a disk rotor in physical contact with the stator. There are three circumferential waves in the stator. The outside diameter of the motor is 10 mm, and the height is 8 mm. The total weight is only 3.5 g. The prototype motor produced a starting torque of 25 gf-cm, a no-load rotational speed of 1200 r.p.m. and a maximum efficiency of about 20%.<
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