US Patent 8740584 Induction motor and hermetic compressor

An induction motor includes a stator having a winding to be inserted to a plurality of stator slots formed along an inner circumferential edge of a stator iron core; and a rotor placed inside of the stator via a gap, the rotor includes a plurality of double squirrel-cage rotor slots formed along an outer circumferential edge of the rotor iron core and filled with conductive material and at least three air hole parts provided around a rotating shaft hole of the rotor iron core to which the rotating shaft is fitted and having an opening which is open to the rotating shaft hole; and an inner diameter part of the end ring which short circuits both edges of the conductive material filled to the double squirrel-cage rotor slot is placed to be adjacent to the air hole part in at least the end ring of one side.