A low voltage piezoelectric micromotor using a thin circular membrane

In this work is described a piezoelectric motor whose stator is composed of a cylindrical steel axis fitted at the center of a thin piezoelectric membrane. The rotor consists of a cylindrical permanent magnet, pressed in contact with the top surface of the axis, by means of magnetic forces. A travelling wave, at the natural flexural vibration of the thin piezoelectric membrane, is excited via piezoelectric effect. The vertical displacement of the membrane is geometrically amplified by the central axis, obtaining a wide precessional motion of the axis. The novelty of the proposed motor is a new transmission mechanism, which is based on the precessional motion. With this motor we obtained a relatively high speed (/spl ap/4000 rpm) by using a commercial piezoelectric membrane (/spl phi/ 32 mm, thickness 0.2 mm), driven at relatively low voltage (/spl plusmn/18 V).