| 摘要 |
PROBLEM TO BE SOLVED: To provide a permanent magnet motor used for information apparatuses such as an HDD (a hard disk drive), capable of reducing cogging torque, in a state where magnetization variations exist. SOLUTION: In response to the magnetization variations, or the magnitude of an error between a switching position of the north pole and the south pole of a permanent magnet 10 and a defined angular position, a surface of an ideal teeth head surface 15gh, facing the permanent magnet, is formed with a variations relief area B, whose radial thickness becomes thicker toward the circumferential edges. When a teeth head surface on the end portion of teeth faces the permanent magnet 10, the ratio between a central gap in the circumferential direction of the teeth head surface and gaps at both edges is set to the optimum value. This enables the basic component of cogging torque and the low-frequency component generated by the magnetization variations, to reduce in a well-balanced manner. Furthermore, this suppresses reduction in counter electromotive voltage and the total magnitude of cogging torque is reduced. COPYRIGHT: (C)2009,JPO&INPIT
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