Abstract: A turbocharger includes: a shaft provided with a small-diameter portion, and two large-diameter portions formed on two sides of the small-diameter portion; and a semi-floating bearing to rotatably support the shaft. The semi-floating bearing includes a cylindrical body into which the shaft is inserted. An inner peripheral surface of the body includes: two bearing surfaces opposed to the large-diameter portions of the shaft; a non-bearing surface located between the two bearing surfaces, having a larger inner diameter than inner diameters of the bearing surfaces; and an oil passage opened to the non-bearing surface to supply lubricant oil to a gap in a radial direction between the non-bearing surface and the shaft. At least one of the two bearing surfaces extends more in an approaching direction of the two bearing surfaces than does the large-diameter portion opposed in the radial direction to the one bearing surface.

Abstract: A bearing structure includes: an outer circumferential groove formed on an outer circumferential surface of a cylindrical portion of a semi-floating metal bearing, and including two opposed surfaces opposed to each other in an axial direction of a shaft and a bottom surface connected to the two opposed surfaces; a radial hole penetrating a wall portion defining the bearing hole so as to communicate with the bearing hole, and facing the outer circumferential groove of the semi-floating metal bearing; a locking member having a body inserted into the radial hole from the outer side of the shaft, wherein at least part of the body is interposed between the two opposed surfaces and fixed to the outer circumferential groove; and an opposed portion provided in the housing, and opposed to the part of the body of the locking member when the locking member is fixed to the outer circumferential groove.

Abstract: An wheel fastening inspection method includes: directly or indirectly applying vibration to a turbine shaft to be inserted to a bearing housing, the turbine shaft being provided with wheels at both ends protruding from the bearing housing, at least one of the wheels being fastened by a fastening member, and a rotary member being fastened by a fastening force generated by the fastening member to the turbine shaft to be integrally rotated with the wheel; measuring the vibration of the turbine shaft; and determining whether or not a vibration frequency at which a peak of the measured vibration of the turbine shaft is given is included in a setting range previously set.

Abstract: A turbocharger includes: a bearing provided in a turbocharger body, and configured to rotatably support a turbine shaft in an insertion hole formed in the bearing; and an opposing portion which faces an end surface of the bearing in an axial direction of the turbine shaft. An end-surface guide portion is provided to any one of an opposing surface of the bearing which faces the opposing portion, and an opposing surface of the opposing portion which faces the bearing. The end-surface guide portion configured to make the insertion hole and an outer peripheral edge of the end surface of the bearing in radial directions of the turbine shaft communicate with each other extends forward in a rotational direction of the turbine shaft from a part of the end surface of the bearing which communicates with the insertion hole.

Abstract: A turbocharger includes: a turbocharger main body; a bearing hole formed in the turbocharger main body; a turbine shaft rotatably inserted into the bearing hole and having a turbine wheel provided on one end and a compressor wheel provided on the other end; a turbine-side bearing part and a compressor-side bearing part rotatably supporting the turbine shaft and disposed in the bearing hole on a relatively turbine wheel side and on a relatively compressor wheel side, respectively; a cooling oil passage provided radially outside the bearing hole in the turbocharger main body and configured to cool the turbocharger main body with lubricating oil circulated inside; a first oil duct configured to guide lubricating oil after lubricating the compressor-side bearing part to the cooling oil passage; and a second oil duct configured to guide lubricating oil after lubricating the turbine-side bearing part to the cooling oil passage.