Motor with diffusion stopper

1. A motor comprising:

a rotation shaft;

a commutator that rotates integrally with the rotation shaft;

a plurality of power supply brushes that contact the commutator in a slidable manner; and

a brush holder that holds the power supply brushes, wherein the brush holder includes

an opposing portion that faces an end face of the commutator in an axial direction,

a bearing holder that holds a bearing located on the opposing portion to axially support the rotation shaft, and

a diffusion stopper arranged in a portion of the opposing portion located toward an outer side in a radial direction from the bearing holder, wherein the diffusion stopper limits diffusion of abrasion powder from the power supply brushes, and the diffusion stopper projects toward the commutator in the axial direction or is recessed in the axial direction, wherein:

the rotation shaft extends through the opposing portion in the axial direction;

the diffusion stopper includes an annular portion that surrounds the rotation shaft;

the bearing held by the bearing holder is an oil-containing bearing; and

the annular portion is located toward the inner side in the radial direction from an outer circumferential surface of the commutator and toward an outer side in the radial direction from the bearing holder as viewed in the axial direction.

2. The motor according to claim 1 , wherein

the diffusion stopper includes a plurality of radial portions that extend in the radial direction and are located toward an outer side in the radial direction from the rotation shaft.

3. The motor according to claim 1 , wherein

the brush holder includes a collecting recess located toward an outer side in the radial direction from the commutator; and

the collecting recess includes an opening that faces an outer circumferential surface of the commutator.

4. The motor according to claim 3 , wherein

the collecting recess includes a tangential collecting recess;

the brush holder includes the tangential collecting recess; and

the tangential collecting recess is located at a position of the brush holder including a tangent of the outer circumferential surface of the commutator extending from a contact point between the power supply brush and the commutator.

5. The motor according to claim 4 , wherein

the collecting recess further includes an auxiliary collecting recess;

the brush holder includes the tangential collecting recess and the auxiliary collecting recess;

the tangential collecting recess is one of two tangential collecting recesses, each located at a portion of the brush holder between adjacent ones of the power supply brushes in a circumferential direction; and

the auxiliary collecting recess is located between the two tangential collecting recesses that are adjacent to each other in the circumferential direction.

6. The motor according to claim 4 , wherein the contact point between the commutator and each power supply brush is located at a position separated in the circumferential direction from a circumferentially middle part of the power supply brush.

7. The motor according to claim 4 , wherein

the plurality of power supply brushes include two power supply brushes;

the two power supply brushes are located toward an outer side in the radial direction from the commutator and arranged at an interval of less than 180° in the circumferential direction; and

the tangential collecting recess includes two tangential collecting recesses each located within an angular range of less than 180° between the two power supply brushes in the brush holder.