Patent ID: 6700269
Filing Date: 2004-03-02
Classification: H02K

Abstract:
A direct current motor comprising a yoke housing and an armature rotatably received within said yoke housing, said yoke housing including:a plurality of primary magnetic poles secured to an inner peripheral surface of said yoke housing for providing magnetic fields to said armature; and a plurality of groove-like reduced thickness portions for increasing a magnetic resistance, said plurality of groove-like reduced thickness portions being integrally formed in said yoke housing, wherein: a number of said plurality of groove-like reduced thickness portions is equal to a number of said plurality of primary magnetic poles; and each said groove-like reduced thickness portion extends along a center line of a corresponding one of said plurality of primary magnetic poles and has an uncovered outer surface on an outside of said yoke housing to expose said entire outer surface of said groove-like reduced thickness portion to air.