Counterbalanced electric motor

摘要

An armature assembly 50 for an electric motor 10 is inherently balanced despite the presence of a secondary shaft 74 extending from a primary armature shaft 72 longitudinally along an eccentric axis 75 offset radially from the longitudinal axis 15 of the primary armature shaft 72. A lamination stack 60 mounted on the armature shaft 70 is formed of a plurality of lamination plates 62 arrayed in abutting face-to-face relationship. The lamination plates 62B and 62C provided at the respective ends of the stack 60 are modified in that some of the radially directed spokes 66 are removed along a selected portion or spaced portions 63,67 of the circumferential extent of the hub portion 64 so as to provide counterweight lamination plates having a spoke pattern which is not symmetric about the longitudinal axis 15 of the primary shaft 72.