Load characteristics of ultrasonic rotary motor using a longitudinal-torsional vibration converter

The characteristics of an ultrasonic rotary motor using a longitudinal-torsional vibration converter of 15 mm to 60 mm in diameter are studied. To obtain ultrasonic motors with a simple structure and large torque, motors using a slitted longitudinal-torsional converter are proposed. The converters have rather simple structures and are driven using only a longitudinal vibration transducer. The vibration converters have 12 to 18 diagonal slits of 45 degrees, 0.5 mm and 1.0 mm width and 10 mm length. The ultrasonic motors designed consist of a vibration converter with a driving part at its free edge, and a rotor part pressed statically to a driving surface using corned disk springs. Maximum revolution over 550 r.p.m. were obtained when vibration converters 15 mm in diameter and 2.5 mm in slit depth of about 60 kHz in frequency, were applied. Maximum torques over 0.3, 11, 17 and 23 Nm were obtained when vibration converters of 15, 40, 50, 60 mm in diameter and of 56 to 23 kHz frequency, were applied.