Patent ID: 8096126

Claim:
A motor-driven supercharger comprising: (a) a turbine shaft having a turbine impeller in one end; (b) a compressor impeller rotationally driven by the turbine shaft; (c) a housing surrounding the turbine impeller, the turbine shaft and the compressor impeller; (d) a motor stator fixed within the housing; and (e) a motor rotor rotationally driven by the motor stator, wherein a portion of the motor rotor is disposed within the motor stator, wherein the motor rotor has a hollow cylindrical sleeve having a through hole surrounding the turbine shaft with at most a slight gap between an inner surface of the hollow cylindrical sleeve and an outer surface of the turbine shaft, and the compressor impeller has a hollow cylindrical hole directly fixing an end portion of the hollow cylindrical sleeve in an axial direction in accordance with the close fit of the motor rotor to the compressor impeller, and wherein the hollow cylindrical sleeve of the motor rotor is directly fixed to an inner diameter side of the hollow cylindrical hole of the compressor impeller in accordance with a close fit so that a gap is not generated between the motor rotor and the compressor impeller when the supercharger is operating.