Design And Research Of A Novel Traveling Rotary Ultrasonic Motor

Ultrasonic Motor (USM) is a new-type motor, which realizes motor drive by using the converse piezoelectric effect of piezoelectric ceramic and the friction coupling of the stator and rotor to convert electrical energy into mechanical energy. It breaks concept of the traditional electromagnetic induction motors. The development history of ultrasonic motor is quite short, but it is showing vigorous vitality. It has a broad application prospect, especially in the aerospace, medical equipment, precision instruments and meters, novel weapons and so on.At present, rotary-type traveling wave ultrasonic motor is one kind of ultrasonic motors which has been widely used. Its distinguishing features include compact structure, high torque at low speed, self-locking function, no electromagnetic interference, displacement of the high resolution etc. It is particularly applicable to small (micro) type of device driver and minutely control. The paper puts forward an innovative type of traveling wave rotary ultrasonic motor. Based on the finite element analysis, this paper deeply studied the stator. The main contents and research results are summarized as follows:1. The principle of energy conversion from electricity to mechanics based on the induced strain by piezoelectric ceramics was analyzed. The structure of traveling wave rotary ultrasonic motor was briefly introduced. Afterwards, the necessary physical conditions to excite traveling wave on the top of stator and the formation of elliptical orbit were explained;2. A dynamic model of ultrasonic motor was established, which was based on energy equivalent principle. It provided theoretical basis for the design of novel traveling wave rotary ultrasonic motor. In addition, the total work of ultrasonic motor in a cycle was analyzed. It composed of the structural loss of the stator, the wastage of frictional heat and the output work of the rotor;3. A traveling wave rotary ultrasonic motor which had an innovative type of exerting pressure was designed. This device adopted the way of stator floated and rotor fixed. Preloading was imposed from the stator to the rotor. Moreover, the stator used radiant panel structure. When the stator was vibrating, air between the radiant panel would flow faster. It can help to eliminate the heat generated by the stator and the rotor in the process of friction drive and prolong the service life of the motor;4. The first three order natural frequencies of the stator of the novel traveling wave rotary ultrasonic motor were studied, based on several experimental instruments, such as vibrator, power amplifier, frequency sweeping signal generator and so on. Then, providing experimental data for verifying the reliability of finite element analysis;5. The application of finite element analysis software ANSYS Workbench at the process of designing the stator of novel traveling wave rotary ultrasonic motor was introduced. Through designing different stator structures and changing the structure parameters of slot width, diameter and thickness of the stator’s radiant panel, using finite element method did modal analysis and harmonic response analysis of the stator. According to the effect of different structural parameters on the natural frequency and the vibration amplitude of the stator, then choosing the final structure parameters of the stator’s radiant panel in the best condition. Finally to achieve the goal of optimizing the structure of stator’s radiant panel.