To increase the output force and improve the contact driving status between stator and output shaft of screw type ultrasonic motor, a cylindrical stator by attaching 12 PZT plates on a metal elastomer was presented. A traveling wave with the 3 wavelengths processing along the circumference of stator was excited to drive the screw output shaft. And a novel screw type ultrasonic motor utilizing the multi-wave-length exciting mode was proposed. The design of ultrasonic motor was given out. The exciting method of multi-wavelength exciting mode was clarified. A vibration mode simulation of stator was carried out by the finite element method. A prototype of screw type ultrasonic motor utilizing the multi-wavelength exciting mode was developed. The dimension of stator is 36 mm × 30 mm × M24 mm (length × width × inner di-ameter). The testing results indicate that the prototype utilizing the multi-wavelength exciting mode can be driven availably. The output velocity and force increase linearly as the exciting voltage rises. A maxi-mum output force 40 N can be obtained at a 52. 1 kHz working frequency and an exciting voltage of effec-tive value 42 V.%为了提高螺纹副驱动型超声电机的输出力,改善定子与输出轴间的接触驱动状态,将12片压电片粘贴至筒状金属弹性体外表面构成定子,激发定子产生一个沿圆周方向行进的波长数为3的驱动行波,实现对螺纹输出轴的驱动,提出一种多波长激振模式的螺纹副驱动型超声电机。给出了电机的设计结构,阐明了定子多波长激振模式的激励方法,利用有限元法对定子的振动模态进行了仿真分析,研制出一台定子尺寸长×宽×内径为36 mm ×30 mm × M24 mm 的原型样机。实验结果表明,采用多波长激振模式可以实现螺纹副驱动型超声电机的有效驱动,电机的输出速度与输出力随激励电压的增大而线性增大。样机工作频率为52．1 kHz,在激励电压有效值42 V 时,最大输出力可达40 N。
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