Patent ID: 6927518

Claim:
A direct current machine comprising: a cylindrical yoke; a plurality of magnetic poles that are continuously arranged one after the other along an entire inner peripheral surface of the cylindrical yoke to provide alternating magnetic polarities along the inner peripheral surface of the cylindrical yoke; and an armature that is received radially inward of the plurality of magnetic poles in the cylindrical yoke, wherein the armature includes: an armature core that includes a plurality of teeth, which are arranged at generally equal angular intervals; and a plurality of armature coils, each of which is wound around a corresponding group of teeth selected from the plurality of teeth, wherein: when one of the plurality of armature coils is in a beginning of a commutation process, a center line of a trailing end tooth of the corresponding group of the teeth, around which the one of the plurality of armature coils is wound, is generally aligned with a corresponding one of a plurality of boundaries, each of which is formed between corresponding adjacent two circumferential ends of the plurality of magnetic poles; and when the one of the plurality of armature coils is in an end of the commutation process, a center line of a leading end tooth of the corresponding group of the teeth is generally aligned with a corresponding one of the plurality of boundaries.