An Ultrasonic Motor with 2 Mm in Rotor Diameter Using Transmission Line and a Spring Washer Driven by a Lagevin Transducer

Ultrasonic micro-motors usually have small torque and small output power. We use regular size Langevin transducer to avoid low input power. Excited vibration is amplified by the stepped horn and propagated through the thin transmission line. Rotation mechanism is fabricated at the tip of the transmission line. In this research, the outer diameter of the rotor is reduced from 5 mm to 2 mm, since the diameter of the endoscope forceps is around 2 mm. Also, the diameter of the transmission line is reduced from 1 mm to 0.5 mm for better flexibility. A spring washer is used to convert the vibration mode and preload is provided by the same spring washer. The preload by the spring washer is about 8 N. Voltage of about 50 Vp-p was applied to the Langevin transducer. When using a transmission line with 1 mm in diameter, the maximum revolution speed and the maximum efficiency were 451.3 r.p.m. and 0.064 %. respectively. And, when using a transmission line with 0.5 mm in diameter, the maximum revolution speed and the maximum efficiency were 109.1 r.p.m. and 0.586 %, respectively.