A ring type standing wave ultrasonic motor using cantilever type longitudinal transducers

The disadvantages of classic ring type ultrasonic motor were analyzed. To obtain large mechanical output power, a ring type standing wave ultrasonic motor using cantilever type longitudinal transducers was proposed. There are four pairs of cantilevers on one side of the ring, and four PZT ceramics are set between each pair of cantilevers. A screw fastened the PZT ceramics and cantilevers together to form a longitudinal transducer. The bending vibration mode of the ring is excited by the stretching vibration of the PZT ceramics. Thus, linear simple harmonic motions are achieved at the particle on the teeth. And the driving force is the frictional force between rotor and stator. The working principle of the proposed motor was analyzed. The ring and the longitudinal transducer were designed with FEM. The sensitive parameters of resonant frequency of the transducer and ring could be gained with modal analysis. The longitudinal vibration modal of transducer and bending vibration modal of ring were degenerated, and the motion trajectories of nodes on the teeth were analyzed. The results of this paper could guide the development of this new type of motor.