Research on excitation mode of piezoelectric tube bend rotary ultrasonic motor

To improve the characteristics of piezoelectric tube bend rotary ultrasonic motor,the force factor formulas of stator under the first and second bending mode were deduced respectively.It seemed that tile force factor of stator under the second bending mode was higher theoretically.A novel excitation mode that the stator was divided into 8 exciting areas was proposed and the second bending mode of stator was implemented.The prototype motor was developed based on the new excitation mode,which stator was 10 mm in outside diameter,8 mm in inside diameter and 35 mm in length. When the pre-load was 1.0 N and peak-peak value of exciting voltage 210 V and the exciting frequency 41.3 kHz,the stalling torque of 2.45 N.mm and no-load angular speed of 206 r/min were obtained.Compared with the same dimension motor that the stator was divided into 4 exciting areas,the stalling torque and no-load angular speed of the novel motor were increased by 17% and 23% respectively.