| 摘要 |
PURPOSE:To prevent a spark from generating by reducing the brush resistance value of the contacting surface of a brush with a commutator in the rotating direction of the commutator so that the value at the center becomes small, thereby enhancing the resistance value when the brush starts or end contacting the commutator segment. CONSTITUTION:The brush resistance value per unit area of the contacting surface 1 of a commutator is increased at both ends and decreased at the center with respect to the rotating direction of the commutator. The ratio of the resistance values is preferably selected to approx. 1/1.1-1/100. Thus, since the resistance of the portion which starts contacting with or separating from the segment increase, a speak generation is suppressed, a brush life is increased, and a noise can be reduce. |
