A cylindrical traveling wave ultrasonic motor using longitudinal and bending composite transducer

A cylindrical type traveling wave ultrasonic motor using longitudinal and bening composite transducer was proposed in this paper. A composite transducer is attached to the cylinder on its outer surface to excite two degenerate flexural vibration modes spatially and temporally orthogonal to each other in the cylinder. In this new design, a single transducer can excite a flexural traveling wave in the cylinder. Two cone type rotors are pressed in contact to the borders of the inner surface of teeth by means of a spring and nut system. The working principle of the motor was analyzed. The resonance frequencies of the two vibration modes of stator were tuned to be close to one another using finite element method. A prototype motor was fabricated and tested. Typical output of the prototype is no-load speed of 281 rpm and maximum torque of 1.2 N m at an exciting voltage of 200 Vrms.