Helical-shaped piezoelectric motor using thermoplastic co-extrusion process

We herein demonstrate a unique helical-shaped piezoelectric ultrasonic motor which can be used as a miniaturized motor, due to its excellent motor characteristics and small physical size. To accomplish this, the thermoplastic co-extrusion process was used as a novel manufacturing method, since it produced a green strip comprised of a pizeoelectrically active layer (PZN-PZT) and an electrically conductive layer (PZN-PZT/Ag) that could be further plastically deformed into a helical shape at 110 °C without difficulty, allowing for the production of a piezoelectric strips with controlled geometry. The stator was found to have large displacements in the rotational and linear directions, at a resonance frequency of 1.32 kHz, which can be used for driving a rotor. In addition, the motor that was produced showed excellent motor characteristics both in terms of its rotational motion and linear motion. Especially, a maximum efficiency of ∼13.8% was obtained at a load force of 60 gf and a velocity of 9.5 mm/s for the linear motion.