| 摘要 |
PURPOSE:To realize high torque and high efficiency by providing a resonator with free and fixed ends, respectively, on one and the other end faces thereof. CONSTITUTION:Upon application of a sine wave having 90 deg. phase shift, bending vibration of primary mode having a node F at a fixed end K and an antinode H on the other end face of an ultrasonic oscillator SE 10 takes place as an elliptical oscillation around a central axis because the SE 10 has the fixed end K on one end face thereof. In other words, force factor increases and electric energy is converted efficiently into oscillation energy, thus rotating a rotor 17 being pressed by the SE 10. When two sine wave voltages are shifted by 180 deg. in phase, rotational direction of the elliptical oscillation is reversed thus rotating the rotor 17 reversely. Contact-free structure from a tightening member 9 can also be realized by making an opening in the top surface of a resonator 6. Furthermore, a groove 6a made in the resonator 6 lowers rigidity in the bending direction to suppress effect of rigidity of the tightening member 9 and maximize the amplitude of oscillation on the upper end face of the SE 10 thus realizing high torque. |
