Dynamo-electric machine having commutator and manufacturing method thereof

摘要

A dynamo-electric machine includes a commutator secured around a rotatable shaft and a plurality of carbon brushes placed in sliding contact with the commutator. The commutator has a sliding contact surface placed in sliding contact with the carbon brushes. The sliding contact surface of the commutator has a plurality of peaks and valleys that are substantially regularly and alternately arranged in both axial and circumferential directions of the commutator.