Patent ID: 9404509
Filing Date: 2016-08-02
CPC Classification: F01D,F04D,F05D,Y10T

Claim Text:
1. A turbocharger comprising: a compressor housing provided therein with an air flow passage in which an impeller is disposed; a bearing housing rotatably supporting a rotor shaft which is connected to the impeller; and a back plate which is disposed between the bearing housing and the compressor housing and which faces a part of the air flow passage, wherein the air flow passage includes a suction port from which air is sucked toward the impeller, and a discharge scroll chamber which is formed on an outer peripheral side of the impeller in a circumferential direction, and which guides compressed air discharged from the impeller to a discharge port, the discharge scroll chamber has such a shape that a cross sectional area thereof gradually increases toward the discharge port in the circumferential direction, the compressor housing includes a scroll piece and a shroud piece which are mutually assembled, the scroll piece includes a cylindrical suction port-forming portion forming the suction port, a suction-side concave surface configuring a suction-side wall surface of the discharge scroll chamber, and a scroll outer periphery disposed on an outer peripheral side of the discharge scroll chamber, the shroud piece includes a cylindrical shroud fit-in portion which is fitted into the scroll piece, an inner peripheral concave surface configuring an inner peripheral wall surface of the discharge scroll chamber, a shroud surface facing to the impeller, and a diffuser surface extending from the shroud surface toward the discharge scroll chamber, the back plate includes a facing surface which is facing to the diffuser surface, an outer peripheral annular fit-in portion which is fitted into the scroll outer periphery of the scroll piece, and an outer peripheral concave surface configuring an outer peripheral wall surface of the discharge scroll chamber, and the outer peripheral concave surface has such a shape that a cross sectional shape thereof formed by a plane including a rotation axis of the impeller gradually changes along the circumferential direction, wherein the back plate is fastened to the bearing housing through a bolt, a shaft hole through which the rotor shaft is inserted, a bolt hole through which the bolt is inserted and an oil discharge port through which lubricant is discharged are formed in a plate central portion of the back plate on an inner peripheral side thereof as compared with the facing surface, and wherein the oil discharge port is dented in a thickness direction of the back plate from a side of the bearing housing.