Motor

DETAILED DESCRIPTION An object of the present invention is to provide a motor capable of preventing the abrasion dust of the brushes from intruding into a ball and roller bearing.
According to the present invention, a motor, wherein: a commutator is fixedly mounted on the outer periphery of a shaft, interposing a distance ring between a ball and roller bearing for rotatably supporting the shaft and itself; a bearing holder fixed to an end bracket is mounted on the outer periphery of the ball and roller bearing: a brush holder stay surrounding the commutator is connected to this bearing holder; and a brush holder incorporating therein brushes being in sliding contact with the commutator is fixed to the brush holder stay; is characterized in that; a labyrinth ring is radially and inwardly projected from the inner periphery of the brush holder stay to provide a labyrinth construction in a space portion extending from the brushes and the ball and roller bearing; and the thickness of this labyrinth ring is determined to be so thin that a volume of a space portion for accumulating carbon formed between the bearing holder and the labyrinth ring becomes as large as possible.
In the above-described motor according to the present invention, the labyrinth ring projectedly provided on the inner periphery of the brush holder stay provides a labyrinth construction in the space portion extending from the brushes to the ball and roller bearing, so that the abrasion dust of the brushes can be prevented from intruding into the bearing, without increasing the number of parts.
Further, the thickness of the labyrinth ring of the brush holder stay is determined to increase the volume of the carbon accumulating space portion as large as possible, so that, even if the abrasion dust of the brushes is accumulated, the accumulated abrasion dust can be prevented from scattering again.
Other objects and features of the present invention will become apparent more fully from the following description.