SINGLE-RESONANCE LONGITUDINAL AND TORSIONAL VIBRATOR COMBINATION-TYPE MOTOR - IMPROVEMENT OF MOTOR CHARACTERISTICS

The present paper deals with the single-resonance longitudinal and torsional vibrator combination-type motor. which is one of the ultrasonic motors with a relatively large torque. To improve the characteristics of this motor. the authors studied the calculation method of the resonance frequencies and designed the motor so that the resonance frequencies of the longitudinal and torsional vibrations were very close to the measured ones, because it was thought that the motor characteristics were largely affected by the degree of approximation of the resonance frequencies. Experimental results have proven that the prototype motor produced large torque with a maximum of 14.0 kgf.cm under a total electrical input power of 30 W; this value was 1.5 times as large as that reported previously. That is, it has been clarified that with sufficient degree of approximation of the resonance frequencies, as mentioned above, the output torque of the motor could be greatly improved; however, its efficiency (maximum of 13.1%) was maintained at almost the same value as before.