| 摘要 |
PROBLEM TO BE SOLVED: To reduce the generation of cogging torque without an excessive reduction in motor torque by being applied to a multiple-pole magnet having four or more poles. SOLUTION: This small motor is constituted by mounting a field magnet having a plurality of poles of four poles or more on the inner peripheral surface of a metal motor case. In the field magnet having the plurality of poles, the magnet member, which has a specified thickness in the radial direction and a specified length in the thrust direction and is integrally formed in a ring shape as a whole, is magnetized. The outer peripheral side in the axial direction is cut off to form a thin part thinned in the axial direction thickness respectively between the magnetic poles. The magnetization is performed by alternately magnetizing S and N poles radially in the peripheral direction. The field magnet can be provided with a notched part at the end part in the thrust direction respectively between the magnetic poles. COPYRIGHT: (C)2008,JPO&INPIT
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