Ultrasonic motor using a one-dimensional longitudinal-torsional vibration converter with diagonal slits

Abstract

Characteristics of ultrasonic rotary motors using a longitudinal-torsional vibration converter 15 mm to 50 mm in diameter are described. To obtain large torque, ultrasonic motors using one-dimensional longitudinal-torsional converters with diagonal slits are proposed. The converters have rather simple and tough structures and are driven using only a longitudinal vibration transducer. The vibration converters are made of metal materials and have diagonal slits cut along the converter circumference adjacent to a nodal position of longitudinal vibration. The ultrasonic motors 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. Vibration characteristics and vibration loci at driving surfaces of these motors are measured under loaded and nonloaded conditions and under forward and reverse rotating conditions. Maximum torques over 0.3 to 23 N m were obtained by the converters 15 to 50 mm in diameter and at frequencies of 80 to 23 kHz. Maximum revolution obtained was over 550 rpm using a 15 mm diameter motor of 56 kHz.