| 摘要 |
PROBLEM TO BE SOLVED: To suppress and stabilize sparks between brush and commutator that increase with rise in the voltage of car-mounted electric components to lengthen the life of a brush, and thereby enhance the durability of a rotating electric machine. SOLUTION: The rotating electric machine includes a commutator fixed on a rotating shaft, and the brushes of positive pole and negative pole in slidable contact with the commutator. The positive-pole brush is formed of a material that forms less graphite coating on the commutator than the material of the negative-pole brush. For example, the positive-pole brush is formed of graphite whose grain size is larger than that of the negative-pole brush. Specifically, the average grain size of graphite of the positive-pole brush is set to a value, for example, greater than 20μm and not greater than 80μm; and the average grain size of graphite of the negative-pole brush is set to a value, for example, not greater than 20μm. Thus, graphite coating is evenly formed under the positive- and negative-pole brushes on the commutator surface, and the production of sparks between brush and commutator is suppressed and wear is suppressed in the brushes and deterioration in the commutator due to the production of sparks. COPYRIGHT: (C)2007,JPO&INPIT
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