Ultrasonic Linear Motor Using Multilayer Piezoelectric Actuators

In order to lower operating voltage and improve the lifetime of an ultrasonic linear motor, we have developed an ultrasonic oscillator with multilayer piezoelectric actuators. Multilayer piezoelectric actuators are operable at low voltage. However, the tensile strength of the multilayer piezoelectric actuator is small. Therefore, the multilayer piezoelectric actuators are build within an elastic body to lower the tensile stress with a compressive preload. Elliptical oscillations are generated by synthesizing two degenerated modes, a first longitudinal mode and a second flexural mode, with π/2 phase difference. As a result of estimating the characteristics of the ultrasonic linear motor with the ultrasonic oscillator, the operating voltage of 10 V p-p , maximum thrust force of 8 N and lifetime of over 5000 hours have been obtained.