| 摘要 |
PROBLEM TO BE SOLVED: To suppress the occurrence of sparks by arranging brushes at proper positions. SOLUTION: A blower motor 1 is provided with magnets 2, 3, a rotor 4 and brushes 5a, 5b. The magnets 2, 3 consist of main magnetic pole parts 2a, 3a and extended parts 2b, 3b formed by extending out the main magnetic poles 2a, 3a, and have flux minimizing parts 2d, 3d at the positions corresponding to the extended-parts start points 2c, 3c. Let the angle the commutator pieces 11 of the commutators 10 make beθ0, and the angle that the end 8b of the rotational direction side of teeth 8a wound with coils 9a, 9b that start rectification and the flux minimizing parts 2d, 3d beθ1. When the position of the end 8b at the rotational direction side of the rotor 4 is treated as negative with reference to the flux minimizing parts 2d, 3d, and its position at the opposite side in the rotational direction as positive, the brushes 5a, 5b are arranged to satisfy the inequality of -0.3<(θ1/θ0)<0.7.
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