Patent ID: 8183740

Claim:
A piezoelectric motor, comprising: a stator having a stator shaft defining a rotational axis; an annular piezoelement having opposing upper and lower surfaces and inner and outer rims, said annular piezoelement retained on said stator and about said rotational axis, and said annular piezoelement comprising a piezoelectric material; an annular wave shell retained on an outer rim of said annular piezoelement; a rotor rotatably and mechanically coupled to said stator shaft, said rotor having a rotor inner circumferential surface; a plurality of elastic pushers, each of said plurality of pushers having a first end mechanically coupled to said annular wave shell and a second end extending to and contacting said rotor inner circumferential surface; and a power supply coupled to said upper and lower surfaces of said annular piezoelement, said power supply operable to provide an alternating voltage that induces a first order longitudinal vibrational mode across said annular width; wherein: a radius of said outer rim (R p ) is at least twice the radius of said inner rim (r p ); an annular width of said annular piezoelement (R p −r p ) is at least twice a thickness of said annular piezoelement; said wave shell is operable to transfer oscillations of said annular piezoelement in said radial direction to said plurality of pushers to effect rotary movement of said rotor about said rotational axis; and said alternating voltage has a frequency (F rP ) approximately equal to c p /2(R p −r p ), where c p is the speed of propagation of sound waves in said piezoelectric material.