Design and analysis of a cylindrical ultrasonic motor using bending transducer

A cylindrical ultrasonic motor using bending transducer was proposed in this paper. The stator components of proposed motor contain a cylinder and four bending transducers, and the four uniform bending transducers are set on the exterior surface of cylinder. The bending of transducers is excited by the longitudinal vibration of PZT ceramics. The four transducers are excited with two different groups of signal, and two bending vibrations are generated on the cylinder. When the amplitude of two bending vibrations is equal, and their phase difference on time and space is pi/2, a traveling wave is formed on the cylinder. Thus, an elliptical motion is achieved at the particle on the tooth. And the frictional force between rotor and stator is the driving force to realize the rotation motion of rotor. The PZT ceramics work with d33 mode, which have high electromechanical coupling efficiency and could improve the output characteristics. The working principle of proposed motor was analyzed. The cylinder and transducers were designed with FEM. The sensitive parameters of resonance frequency of transducer and cylinder were gained with modal analysis. The bending resonance frequency of transducers and cylinder were degenerated, and the motion trajectories of nodes on the teeth were analyzed. The result of transient analysis shows that the trajectory of node on the tooth is nearly an ellipse. The results of this paper could be useful in the development of this new type of motor.