Piezoelectric Motor Utilizing an Alumina/PZT Transducer

To enhance the torque and output power of the rod-shaped piezoelectric rotary motors, in this article, we employ alumina to substitute the metal parts of the transducers considering that the high Young's modulus of alumina may avoid preload-induced vibration reduction and enable the transducers to generate the high driving force. Besides, alumina exhibits a relatively low density compared to most of the materials commonly used as the vibrating bodies (except aluminum alloy); this probably enhances the power densities of the piezoelectric motors. To assess the validity of our proposal, we constructed a Langevin-type alumina/lead-zirconate-titanate (PZT) motor and investigated its load characteristics. The transducer of 35 mm in outer diameter operated in orthogonal bending (B 2 ) modes and drove the rotor with its end surface. The alumina/PZT motor yields the maximal torque and maximal output power of 1.56 N·m and 26.0 W, respectively, both of which exceed those of the metal/PZT motors having identical structure and working in B 2 modes. Additionally, its power density reaches 56.3 W/kg, relatively high among the rod-shaped rotary motors although some of which work in more powerful modes. This article validates the effectiveness of our proposal and provides a new approach to improve the performance of the rod-shaped piezoelectric rotary motors.