Traveling Ultrasonic Motors Based On Effective Elliptic Motion And Structural Force Factor

The Ultrasonic Motors are expected to apply in some driving applications because they have some advantages which the traditional mangnetic motors can not have. Domestic and foreign scholars have done many researches on this kind of motor, especially on the traveling ultrasonic motor. Most of the researches have focused on developing new type of traveling ultrasonic motor based on the basic driving principle, and studying the performance of motor from the standpoint of electric circuit and materials. There exist certain deficiencies of the ways metioned above due to sperating the performance from the driving principle of USM. This dissertation further research the output performance of the USM based on the driving principle of traveling wave USM. Then two new types of traveling wave ultrasonic motors are designed on the base of the research achievments shown in this paper.The generation and characteristic of the traveling wave are analysed based on the theory of wave and vibration in elastic body. The activating mechanism and condition of traveling wave in, elastic body are studied in this dissertation using theoretical and simulation method. The results show that lamb wave and beam bending wave are two different kinds of traveling wave which have different boundary, and characteristics. The beam bending wave owns some advantages such as single mode, easily activating pure traveling wave. The traveling wave can be activated in elastic beam by means of superposition method with modal standing wave, and also can be produced directly.Travelling wave can make particle move on an elliptical locus and the shape of the ellipse trajectory directly affect the motor output characteristic. The characteristics of the particle ellipse trajectory on the stator surface are analysed theoretically in this dissertation.The elliptical motion of particles is decomposed into the effective elliptic motion and the radial linear motion. The effective elliptical motion drives the rotor directly, and the linear motion produces relative sliding between the stator and rotor, and thus produces energy loss. The reseach results will be the theoretical supports of the Hula-hoop type ultrasonic motors.Ultrasonic motor is an electromechanical coupling system, so the energy loss in the process of transformation between the mechanical field and electrical field can be analyzed and the efficiency of ultrasonic motors can be researched from the perspective of energy. The Electromechanicalcoupling equation of the vibrator is derived, and the piezoelectric vibrator force coefficient can be expressed as the product of the material force coefficient and the structure force coefficient. The structure force coefficient is directly related to the energy loss of ultrasonic motor, which affect the efficiency of motors. By means of simulation, it is verified that the structure force coefficient can be decreased by changing the geometry of the stator, for example, the ring-type and cylinder traveling ultrasonic motor. The results show that the efficiency of the motor can be improved by changing the structure force coefficient.The conclusions and results in this dissertation can be used in the design of traveling wave type ultrasonic motors. A new type of spring stator traveling wave ultrasonic motor is designed to improve the lamb wave spring stator ultrasonic motor using the mehod superposition by standing waves. According to the principle of decomposition of elliptic motion, a new type of Hula-hoop traveling wave ultrasonic motor is designed driving rotor by axial midpoint of the cylinder and the topology and some parameters of the stator is optimized based on the structure force coefficient method. The results show that the performance of both motor is improved, which verify the theory provided in this dissertation.