Patent ID: 9148038
Filing Date: 2015-09-29
Classification: F04D,H02K

Abstract:
1. An electric motor comprising a stator and a rotor, the rotor comprising: a shaft having a mounting structure formed at one end thereof for connection to a load; a rotor core fitted to the shaft, the rotor core formed by stacking together a plurality of laminations and having a plurality of salient poles arranged along a circumference thereof, each pole comprising a neck portion and an arced head portion; and a commutator fitted to the shaft; wherein the mounting structure causes a center line of gravity of the rotor to deviate from a rotational axis of the rotor, the rotor core defining a first hole in the head portion of a first one of the poles, said first pole being closer to the center line of gravity of the rotor than at least one other pole, the first hole extending from a first axial end of the rotor core to an axial middle portion of the rotor core, the first hole being formed by aligning first cutouts formed in corresponding laminations before stacking; wherein the rotor core defines a second hole in the head portion of a second one of the poles, said second pole being further from the center line of gravity of the rotor than the first pole, the second hole extending from a second axial end of the rotor core to an axial middle portion of the rotor core, the second hole being formed by aligning second cutouts formed in corresponding laminations before stacking; and wherein the first hole and the second hole axially extend from opposite axial ends of the rotor core in opposite directions.