| 摘要 |
PURPOSE:To improve efficiency of a motor by placing a block between a metal block placed on a rotor and a piezoelectric-ceramic element for longitudinal vibration. Such a block is made of the material, the product of the density and the modulus of elasticity of which is more than that of the material of the metal block, and has recesses at the side contacting the metal block. CONSTITUTION:A voltage is applied to a longitudinal piezoelectric element 11 and a torsional piezoelectric element 12, and the phase difference of the voltage is properly adjusted. And during high power excitation, by letting the resonance frequencies of a longitudinal and a torsional vibrations be equal to each other, a strong elliptic vibration with an amplitude produced by combining a longitudinal vibration with a torsional vibrations can be generated at the boundary surface of a stator and a rotor. A projected section 14c of a head mass 14b has little stiffness to the longitudinal vibration and does not affect the resonance frequency of the longitudinal vibration, but serves as a great inertial mass to the torsional vibration and remarkably reduces the resonance frequency of the torsional vibration. |
