Patent ID: 8001781

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 motor stator fixed within a housing; (D) a motor rotor rotationally driven by the motor stator; and (E) a thrust bearing rotatably supporting a thrust force applied to the turbine shaft, wherein the thrust bearing comprises i. a small-diameter disc-shaped thrust collar rotating together with the turbine shaft; and ii. a turbine side thrust bearing and a compressor side thrust bearing that block movement of the thrust collar in an axial direction, wherein the compressor side thrust bearing is disposed on a side closer to the compressor impeller than the thrust collar in the axial direction, and wherein the compressor side thrust bearing comprises a. a small-diameter ring portion including a thrust surface that is in contact with the thrust collar on a turbine side and the thrust surface has approximately an equal diameter to that of the thrust collar; b. a truncated conical portion that has a conical outer surface that gradually increases to the turbine side from an outer peripheral surface of the small-diameter ring portion; c. a flange portion that is positioned at a turbine side end portion of the truncated conical portion and that is fixed to the housing closer to the turbine than the thrust collar; and d. an oil supply flow path that opens on the thrust surface and supplies a lubricating oil to the thrust surface, and the small-diameter ring portion and the flange portion are located at different positions in the axial direction.