DEVELOPMENT OF A PIEZOELECTRIC CYCLOID MOTOR

Ultrasonic motors have recently been developed which have the advantage over electromagnetic motors that they give high torque at low speed. However, since they are driven by friction between their stator and rotor, they have a problem with wear and, as a result, with the length of useful life. This paper proposes a new piezoelectric cycloid motor, in which the cycloid gear mechanism is used to convert the expansion and contraction of the piezoelectric actuators into the rotational motion of the rotor, Since the motor has no slip motion between its stator and rotor, it is not affected by friction. The fundamental characteristics are theoretically derived, and are examined using a prototype of the motor. The following results are obtained: it rotates steadily and keeps its rotational speed even when the load is increased up to the maximum output torque, 0.014 Nm; the maximum efficiency is 25.5 per cent, which is obtained at 16 rpm within the measuring range of the driving frequency of the motor.