A new low voltage piezoelectric micromotor based on statorprecessional motion

摘要

In this work a piezoelectric motor is described whose stator isncomposed of a cylindrical steel axle fitted at the center of a thinnpiezoelectric membrane. The rotor consists of a cylindrical permanentnmagnet, pressed in contact with the top surface of the axle, by means ofnmagnetic forces. A travelling wave, at the natural flexural vibration ofnthe thin piezoelectric membrane, is excited via the piezoelectricneffect. The vertical displacement of the membrane is geometricallynamplified by the central axle, obtaining a wide precessional motion ofnthe axle. On this motion is based the transmission mechanism of thenproposed motor. The motor is able to give a relatively high speedn(≈3500 rpm) and torque (1.8·10-5 N·m) bynusing a commercial piezoelectric membrane (diameter 32 mm, thickness 0.2nmm), driven at relatively low voltage (18 V P-P). The very smallnthickness of the stator makes this motor suitable for microsystemnapplications. A simple analytical model of the transmission mechanism isndiscussed, and the predicted results are compared with experimentalnmeasurements, with a satisfactory agreement