Experimental study on high efficiency ultrasonic motors using lubricant

Ultrasonic motors have hit the bottleneck due to their low efficiency and short life, which limit them in some niche markets. On the other hand, lubrication in contacting interface of ultrasonic motors is a promising way to improve motor efficiency and prolong life. In this paper, a high efficiency ultrasonic motor was achieved by introducing lubricant into ceramic contacting interface. The maximum efficiency as high as 85% was realized, which is the record efficiency of this type ultrasonic motor. Motor efficiency was improved with static preload increasing, which was a different feature from general characteristics of ultrasonic motor in dry condition. Our experimental investigation also supports the notion that the friction materials still play an important role in motor efficiency and stability, whereas no obvious distinction of lubricating effect was observed when different lubricants were tested in this experiment.