A Bonded-Type Piezoelectric Actuator Using the First and Second Bending Vibration Modes

A piezoelectric actuator, which is constructed by bonding six pieces of lead zirconate titanate (PZT) ceramic plates on a step aluminum alloy beam, was proposed and tested for the design of a small-size rotary driving appratus. Two pieces of PZT ceramic plates bonded in the middle part is used to generate the first bending mode, whereas the other four on the two sides are set for the excitation of the second bending mode; their superimposition can produce elliptical movements on the two ends of the beam, which can rotate a disk-shaped rotor. Compared with the traditional ring-shaped traveling-wave piezoelectric actuator, the proposed actuator has a simpler structure and operating principle; it also gives a new mode for rotary driving. The resonance frequencies of the first and second bending modes were designed to be close at about 21.1 kHz. The maximum no-load speed and torque were tested to be 158 r/min and 0.053 N · m, respectively. The prototype achieved a power density of 19.0 W/kg under a weight of 15.8 g. The proposed combination plan of the first and second bending modes is very suitable for constructing a small-size piezoelectric actuator, which exhibits merits for application in small systems.