Abstract
This study aims at developing an out-off-plane mode ultrasonic motor with notched thin-disk vibrator. The vibrator made of a piezo buzzer (diameter is 31 mm, thickness is 0.2 mm) with asymmetric notched design can be excited by electric to produce an out-off-plane elliptical displacement motion to directly actuate a rotor with 2 mm axis high-speed rotating above a driving screw located at vibrator’s center. Structure-oriented design of the vibrator can let the driving frequency located in the main electric-mechanical coupling area of piezo material and thus promote the motor’s performance significantly.A thin disk with three notches distributed as an unequal triangle 110°-120°-130° and with another smaller plate below it composed together is proposed as best vibrator’s structural among many designs in this study. The design measures are: (a) take notches in place of fixed bolts to release vibrator’s boundary and concentrate energy on driving screw, (b) unequal triangle 110°-120°-130° notched design can promote the torque of driving screw, (c) combine another smaller plate under the vibrator can stabilize the operating direction and extend the preload range. Elliptical displacement motion on driving screw of the proposed vibrator is verified via numerical simulation by finite element analysis method. The mode frequency of proposed structure whether locates in the main electric-mechanical coupling area of piezo material is also checked by impedance analysis scanning with HP4194 and power amplifier. Finally, carbon powder lithography and experiment on performance of proposed motors are conducted to verify the design and simulation results.Experiences show that the performance enhances outstandingly for the three notches 110°-120°-130° double plates’ ultrasonic motor proposed in this study as compared to those three phases out-off-plane mode ultrasonic motor proposed by Ouyang [13], for example the power consumption decreases from 1.5 W to 1 W (saving about 33.3 %), the rotating speed promotes from 3000 rpm to 5300 rpm (increasing about 76.6 %), and the torque enhances from 0.5 mN-m to 1.28 mN-m (promoting about 156 %). The developed motor with thin structure is suitable for applying to slender 3C products and has advantage of cost.