Patent ID: 6731040
Filing Date: 2004-05-04
Classification: B62D,H01R,H02K

Abstract:
A brush motor for an electric power steering system comprising:a four-pole field portion fixed to an inner wall surface of a yoke; an armature including; windings wound around a core with 22 slots to constitute a lap winding, hooks which are formed on one ends of 22 commutator segments respectively and on which the windings are hooked, and a cylindrical commutator which is constructed by molding integrally the commutator segments with a resin so that convex portions for preventing fling-out of the commutator segment are provided on an inner peripheral surface side of each commutator segment to extend over an almost full length in an axial direction; and four brushes which contact slidably to outer peripheral surfaces of the commutator segments; wherein when the commutator to which a sliding contact portion of the brush contacts is sectioned perpendicularly to an axial direction, a relationship of 0.18&lE;(AÃ—N)/(DÃ—D)&lE;0.23 is satisfied, where A is a sectional area (mm2) of one commutator segment, N is a number of the commutator segments, and D is a diameter (mm) of outer peripheral surfaces of the commutator segments.