Principle and Operation of the New Type Motor Consisted of Piezo-Electric Device and Strain Wave Gearing

Abstract

Authors have developed a new type of motor composed of piezo-electric device and strain wave gearing, which is called piezo-electric motor, as a first stage to realize a low speed motor with small size and light-weight. The principle of the motor is that the traveling wave is produced by piezoelectric devices and displacement conversion devices without mechanical resonance and the torque to rotate the motor is generated by a mechanism of strain wave gearing (circular spline and flexspline) without using friction. The motor is operated in variable frequency and have its rotational position (angle) controlled in open-loop because it is basically a synchronous motor. In this paper, the structure and principle of the proposed motor are explained and the driving method and the mechanical characteristics of an experimental motor are also described.
The results are as follows;
(1) The proposed piezo-electric motor is experimentally verified realizable. The experimental motor operates in 2, 920 step per revolution, and its speed range is 0_??_960 pps _??_or 0_??_20 (rpm)_??_.
(2) The torque characteristics are clarified qualitatively.
(3) The generated torque of the experimental motor is small (less than 0.03 Nm) and therefore the improvement of the torque is an important subject here after.
(4) It is possible to construct the motor with nonmetallic material. This fact is considered to make a way to lighten the motor in weight in the future.