Patent ID: 7615908

Claim:
An alternator for a vehicle, comprising: a frame supporting a stator having a stator winding; a rotary shaft rotatably supported with the frame and having slip rings; a rotor fixedly carried on the rotary shaft to be rotatable inside the stator and having a field winding electrically connected to the slip rings; a brush unit fixed to the frame and having a brush holder, formed with brush accommodating portions for holding brushes in areas above the slip rings in sliding contact therewith, respectively, a slip ring accommodating section for covering outer peripheries of the slip rings, springs for pressing the brushes toward the slip rings, respectively, and a sealing plate member coupled to the brush holder for covering the outer peripheries of the slip rings, the brush unit having one end face formed with an opening portion, axially opening toward the frame and surrounding the rotary shaft, which is spaced from the frame with a clearance that is substantially sealed, and the other end face closed with the brush holder and the sealing plate member; and a brush-wear particle collecting member placed in close proximity to at least one of the slip rings in an area below the slip rings and associated with the brush holder for collecting brush-wear particles generated by the brushes in sliding contact with the slip rings, wherein the brush-wear particle collecting member includes a brush-wear particle collecting section, formed on the sealing plate member in the area below the slip rings, which has a narrowed wear-particle drop-off passage through which the brush-wear particles are guided to the brush-wear particle collecting section.