| 摘要 |
PURPOSE:To regulate resonance frequency of a stator to the same characteristic by forming a protrusion for regulating the resonance frequency of the stator integrally with the stator. CONSTITUTION:A protrusion 12b for regulating a resonance frequency is integrally formed at a stator 12. The protrusion 12b radially protrudes from the outer periphery of the stator 12. The protrusion 12b is an annular protrusion circulating at the outer periphery of the stator 8, and disposed in the extended surface of a bending neutral surface so as not to alter the bending rigidity of the stator 12. Since the protrusion 12b alters the mass per unit length of the outer periphery of the stator 12, its resonance frequency is varied. A frequency range to be regulated by the protrusion 12b can be suitably set according to its size. If the protrusion 12b is formed thick or largely protrudes from the outer periphery of the stator 12, the regulating range of the frequency can be increased. |
