The Design, Facture And Mechanism Simulation Of The Traveling Wave Ultrasonic Motor

Ultrasonic motor (USM) is a new type direct drive motor of using anti-piezoelectric effects of piezoelectric ceramics for ultrasonic vibration and transform the electric energy to the mechanical energy. As compared with conventional electromagnetic motor, the ultrasonic motor possesses the following features: compactness in size, high-torque at a low-speed range, fast response, insensitive to magnetic fields, high holding torque when power is off, and so on. Ultrasonic motor has wide application foreground in many fields such as aerostat, spacecraft, automobile, biology, physic, precise positioning devices, and so on, so it has been paid more and more attentions and has been studied as a main issue by the scientists in many countries. The research object of this thesis is traveling wave ultrasonic motors (TWUSM). We focus our attention on the investigation of TWUSM and piezoelectric ceramics for TWUSM in this dissertation. The thesis mainly studies the demands of the piezoelectric materials for the motor, the fabrication of the ceramics, the FEM modeling of the motor, the manufacture of the motor, and so on.To discuss the motor's property demands of the piezoelectric materials, the finite element method, the traditional theory method and the equivalent circuit method are utilized in this paper. The simulation result indicates that the increase of the piezoelectric constant (especially the d₃₁), can increase the vibration displacement of the stator considerably;the change of the elastic compliance constant contribute little to the vibration displacement, but it can adjusts the vibration frequency effectively;the dielectric loss can bring the excess heat of the motor, which will influence the output velocity of the motor.According to the requirement of the TWUSM, the rules of designing multi-system ceramics were proposed. Under the guide of these rules, we doped the PSN-PZN-PZT with Mn. The experiment result shows that the PSN-PZN-PZT ceramics have better comprehensive electromechanics performance when the weight concentration of Mn is 0.5wt%;its frequency temperature stability performance also gets great improvement, so this kind of ceramics is hopeful to getapplication in the ultrasonic motor.The stator of the motor is constructed using the ceramics we have made. Then we built the finite element model of the stator in ring-type TWUSM utilizing ANSYS program. The stator's resonance frequency is confirmed and the optimized mode is chose. In view of piezoelectric effect of the piezoelectric ceramics, the optimization of many structural parameters such as the height of the teeth of the stator, the thickness of the piezoelectric ceramic, are decided, which provides theory guidance to the optimum design of the TWUSM stator.On the basis of optimum design of TWUSM, the best composition of the PSN-PZN-PZT is used in the stator of the motor. The capacitance, impedance and admittance near the B09 mode were also investigated, which provides the experimental evidence for the design of drive circuit. The calculated results of the resonance frequency from the finite element method were in good agreement with the measured experimental data. Working with the drive circuit, the motor can achieve the following features: output torque is 0.80N-m;load-free revolution speed is more than lOOrpm;the output position precision is 30';the efficiency of the TWUSM is more than 27%.