An ultrasonic motor using transmission line and spiral structure driven by a Langevin transducer

An ultrasonic micro-motor usually has small torque because of its small sized rotor. If we can use large sized transducer, such as bolt clamped Langevin transducer, we can expect an ultrasonic micro-motor with high performance. In this research, a Langevin transducer with 31.5 mm in diameter is used to drive a rotor with 5 mm in diameter. Spiral structure is used to excite both longitudinal and torsional vibration to drive the rotor. The maximum revolution speed was 147 r.p.m. at applied voltage of 60 Vp-p, the maximum torque was 0.061 mNm at applied voltage of 60 Vp-p, and the maximum driving efficiency was 0.0059 % at applied voltage of 50 Vp-p.