Disc-type commutator for electric rotating machine

Details

Inventors: Ebihara, Jiro; Ohta, Hajime; Ito, Akiyasu;
Assignee: Denso Corporation (Kariya, JP)
Primary Examiner: Nguyen; Tran
Assistant Examiner: Mohandesi; Iraj A
Attorney, Agent or Firm: Oliff & Berridge, PLC

A disc-type commutator is mounted on a rear end surface of an armature of an electrical rotating machine. Plural commutator segments are radially arranged around a rotating shaft, separated from one another by radially extending commutator gaps. A width of the commutator gap is gradually widened along a radial direction of the commutator, so that foreign particles, such as swarfs or brush dusts, entered in the commutator gap are removed by a centrifugal force generated in rotation of the armature. Further, the width of the commutator gap may be gradually widened along its depth direction so that the width becomes wider at its open end that at its closed end.

DETAILED DESCRIPTION The present invention has been made in view of the above-mentioned problem, and an object of the present invention is to provide an improved disc-type commutator in which foreign particles entered into the segment gaps are easily removed.
The disc-type commutator is composed of an insulating disc and plural commutator segments radially disposed on the insulating disc, forming a commutating surface.
The commutator segments are separated from one another by segment gaps formed between neighboring commutator segments.
The disc-type commutator is mounted on a rear end surface of an armature of an electric rotating machine so that the commutator surface is positioned perpendicularly to a rotating axis of the armature.
Conductors forming an armature coil disposed in slots of an armature core are electrically connected to the commutator segments.
One end of the segment gaps in the axial direction is open to the commutating surface and the other end is closed by the insulating disc.
A width of the segment gap in a rotational direction of the armature is narrow at the radial inside of the commutator and gradually widened toward the radial outside.
The width may be made more than twice wider at the radial outside than at the radial inside.
Swarfs entered into the segment gaps in a process of machining the commutating surface and foreign particles such as brush dusts entered during operation of the rotating machine are easily removed from the segment gaps by a centrifugal force generated by rotation because the segment gaps are widened at the radial outside.
Further, the width of the segment gap is gradually widened along the axial direction, so that the segment gap is the narrowest at its closed end contacting the insulating disc and the widest at its end open to the commutating surface.
The segment gap may be widened symmetrically with respect to the axial direction, or asymmetrically widened by making a forward side surface of the commutator segement facing the rotational direction slanted more than a backward side surface

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