Bi-direction quasi-travelling wave piezoelectric rotary motor with single vibrator.

In this paper, a cylindrical piezoelectric quasi-travelling wave motor, which used only a single vibrator to generate bidirectional rotations by changing the driving signal frequencies, was presented. The stator of the proposed motor consists of a metal tube and one piece of piezo-plate bonded onto the tube. Because of the asymmetric structure design, the single piezo-plate can excite two degenerated bending modes at one resonant frequency for generating rotation; while it can also excite a torsion mode and a bending vibration at another resonant frequency for generating reverse rotation. The prototype motor, whose stator was 6 mm in diameter and 26 mm in length, can rotate anticlockwise at a driving frequency of ∼51 kHz and clockwise at a driving frequency of ∼58 kHz. The motor achieved a maximum speed of 606 rev min⁻¹ and a stall torque of 1·08 mN m under a driving voltage of 116Vp-p. This research has provided a design way for piezo-motor miniaturisation. [ABSTRACT FROM AUTHOR]