| 摘要 |
PURPOSE:To reduce the loss and to increase the lifetime of a rush unit by disposing a carbon brush element having a small specific resistance at a commutation starting side and a carbon brush element having a large specific resistance at a commutation ending side, and integrating them to form a brush. CONSTITUTION:The first carbon brush element 7a having a small specific resistance is disposed at a commutation starting side with respect to the rotating direction A of a commutator 1, the second carbon brush element 7b having a large specific resistance is disposed at a commutation ending side, and integrated to form a carbon brush 7. Then, the brush 7 is pressed in contact with the periphery of the commutator 1 by a brush spring 5. Thus, since the specific resistance of the entire brush 7 decreases, the loss of the brush can be alleviated and preferably commutating action can be obtained to suppress the spark, thereby performing a long service lifetime. |
