A Rotary Piezoelectric Actuator Using the Third and Fourth Bending Vibration Modes

A piezoelectric actuator using the third and fourth bending vibration modes was proposed, designed, fabricated and tested with the aim of accomplishing rotary driving by boltclamped transducer. By superimposing the third and fourth bending vibrations, elliptical movements are formed on the two leading ends of the actuator. When a ring type rotor is in contact with the two diving tips and the vertical preload is applied, the horizontal movements of the driving tips generated by the third bending vibration will push the rotor into motion by frictional forces while the vertical movements produced by the fourth bending vibration will overcome the preload. A method of tuning the resonance frequency of the third bending mode to the fourth bending one was discussed. The horn shape was adjusted to make the two bending modes have nearly uniform frequencies. The vibration characteristic and mechanical ability of a prototype were tested, and the tested resonance frequencies agreed well with the calculated ones. The prototype achieved maximum speed and torque of 86 r/min and 2.5 Nm, respectively.