Simulation and Experimental Study of a Compact Ultrasonic Clutch

To meet the requirements of compact clutches in precision transmission systems under space and mass constraints, a novel compact ultrasonic clutch was designed using the ultrasonic near-field levitation theory. The clutch employs a sandwich piezoelectric ultrasonic transducer and a preload spring as core components, achieving engagement and disengagement through acoustic radiation pressure generated by 60 kHz high-frequency vibration. The dimensions of the ultrasonic transducer were designed using the four-terminal transmission matrix method, and modal analysis as well as dimensional optimization were performed through finite element simulations. Simulations analyzed the influence of input voltage and levitation height on the output radiation acoustic pressure in the near-field levitation system, verifying the feasibility of applying this theory to miniature ultrasonic clutches. Experiments were carried out to measure the output rotational speed and load torque of the clutch under different input power levels at rotational speeds of 100 r/min and 200 r/min. The results demonstrate that the designed ultrasonic clutch can reliably achieve both separation and engagement. Furthermore, comparative tests on the output torque of the ultrasonic clutch with contact surfaces of different roughness levels indicate that the output torque exhibits a nonlinear increase with increasing surface roughness.