Chen Y, Liu Q L, Zhou T Y
Department of Physics, Tsinghua University, Beijing 100084, China.
Ultrasonics. 2006 Dec 22;44 Suppl 1:e581-4. doi: 10.1016/j.ultras.2006.05.055. Epub 2006 Jun 5.
A traveling wave ultrasonic motor of high torque with a new configuration is proposed in this paper. In the new design, a part of the motor serves as the stator. The rotor is the vibrator consisting of a toothed metal ring with piezoelectric ceramic bonded, which generates ultrasonic vibration. The rotor is in contact with the shell of motor and is driven by the friction between the rotor and the stator. This configuration not only removes the rotor in a conventional type of traveling wave ultrasonic motor but also changes the interaction between the rotor and the stator of the motor so that it improves the output performance of the motor. Although an electric brush is added to the ultrasonic motor, it is easy to be fabricated because of the low speed of motor. The finite element method was used to compute the vibration modes of an ultrasonic motor with a diameter of 100mm to optimize the design of the motor. A 9th mode was chosen as the operation mode with a resonance frequency about 25 kHz. According to the design, a prototype was fabricated. Its performance was measured. The rotation speed-torque curves for various frequencies were obtained. The result shows that its stall torque is greater than 4 Nm within a range of 400 Hz. This ultrasonic motor was used to drive the window glass of a mobile car and the result was satisfactory. In the further the research on the friction material between the stator and the rotor is under way to improve the efficiency of the ultrasonic motor.
本文提出了一种具有新型结构的高转矩行波超声电机。在新设计中，电机的一部分用作定子。转子是由粘结有压电陶瓷的带齿金属环组成的振动器，其产生超声振动。转子与电机外壳接触，并通过转子与定子之间的摩擦力驱动。这种结构不仅去除了传统型行波超声电机中的转子，还改变了电机转子与定子之间的相互作用，从而提高了电机的输出性能。虽然超声电机增加了电刷，但由于电机转速低，易于制造。采用有限元方法计算了直径为100mm的超声电机的振动模式，以优化电机设计。选择第九阶模态作为工作模态，共振频率约为25kHz。根据设计制作了样机，并对其性能进行了测试，得到了不同频率下的转速-转矩曲线。结果表明，在400Hz范围内其堵转转矩大于4Nm。该超声电机用于驱动汽车的车窗玻璃，效果令人满意。进一步正在开展对定子和转子之间摩擦材料的研究，以提高超声电机的效率。
