Adhesion theory of frication model and characteristics of hybrid transducer type ultrasonic motors

High torque as one important characteristic of longitudinal-torsional hybrid transducer-type ultrasonic motor (HTUSM) is mainly caused of discontinuous-surface-connect mode between the stator and the rotor which is different from the many-point-connect mode of traveling wave motors. Therefore, it is important that one connect friction model is proposed to analyze this connect mode between the stator and the rotor. In this paper, according to the adhesion theory of friction, an advanced equivalent circuit of the motor which contains both the longitudinal vibrator and torsional vibrator is proposed. Based on this model, a design method of a longitudinal-torsional hybrid transducer-type ultrasonic motor (HTUSM) aimed at practical uses of the motor is presented. All factors that influence the mechanical characteristics are analyzed, and low-efficient of this type motor is explained. Based on this study, mechanical characteristics of the motor such as the maximum torque, efficiency and the no-load speed and preload are determined.