Patent ID: 8304954

Claim:
A commutator motor comprising: a hollow cylindrical yoke having an open end; an end frame that closes the open end of the yoke, the end frame having a cylindrical side wall that engages with the open end of the yoke and an end wall that covers the open end of the yoke; a field arranged on an inner periphery of the yoke; an armature surrounded by the field to generate torque, the armature including an armature shaft that has an end portion rotatably supported by the end frame via a bearing; a commutator that is provided on the end portion of the armature shaft; a plurality of brushes that slide on the outer surface of the commutator during rotation of the armature shaft; a plurality of springs each of which presses a corresponding one of the brushes against the outer surface of the commutator; and a brush holding device that holds the brushes along with the corresponding springs, wherein the brush holding device includes a plurality of brush holders and a substantially annular holder plate, each of the brush holders includes a holder frame, which receives therein a corresponding pair of one of the brushes and one of the springs, and a bottom plate that has two opposite side portions, the holder plate is disposed around the commutator and has a major surface on which a plurality of pairs of guide walls are formed at given intervals in a circumferential direction of the holder plate, each pair of the guide walls defining a pair of grooves in the holder plate, the side portions of the bottom plate of each of the brush holders are respectively fit in a corresponding pair of the grooves defined by the guide walls in the holder plate, each of the brush holders has a radially outer end that abuts an inner surface of the side wall of the end frame, whereby radially outward movement of each of the brush holders is restricted by the end frame, the brush holding device further has temporary fixing means for temporarily fixing each of the brush holders, which has the corresponding pair of brush and spring received therein, at a given position on the major surface of the holder plate in assembling the brush holders to the holder plate, and for each of the brush holders, the radially outer end of the brush holder abuts the inner surface of the side wall of the end frame with the temporary fixing means disabled and with the brush holder radially moved from the given position.