Patent ID: 7064467

Claim:
A commutator motor, comprising: a stator comprising a stator yoke having a tubular shape and extending in an axial direction and having an inner peripheral surface, and a field magnet fixed to the inner peripheral surface of the stator yoke for providing a field magnetic pole in the stator; and an armature rotatably disposed within the stator; wherein the stator yoke is comprising at least one of (a) a plurality of plate-like annular bodies having iron parts which are stacked on each other coaxially in the axial direction of the stator yoke, and (b) a plurality of substantially identically configured iron plate-like arcuate bodies disposed at such position as to form a part of virtual annular bodies and which are stacked on each other coaxially in the axial direction of the stator yoke; wherein the plurality of plate-like annular bodies or the plate-like arcuate bodies adjacent to each other in the stacked direction are fixedly connected to each other by caulking, wherein a non-magnetic portion is defined by a hollow groove extending in the axial direction of the stator yoke and formed in the inner peripheral surface of the stator yoke with a depth of the groove extending partially into the stator yoke, and wherein the stator yoke has the non-magnetic portion at a substantially center portion of the field magnetic pole in a radial cross-section of the stator yoke.