A scroll structure of a centrifugal compressor includes, of a flow passage connection section where a scroll start portion and a scroll end portion of a scroll flow passage intersect, a connection region where a first inner circumferential surface of the scroll end portion in the centrifugal compressor and a second inner circumferential surface of the scroll start portion in the centrifugal compressor are connected. The connection region includes a turning start point where a direction starts to change from the first inner circumferential surface toward the second inner circumferential surface, and a turning end point where the change in direction from the first inner circumferential surface toward the second inner circumferential surface comes to an end. Where a cross-section orthogonal to an extension direction of a center line of the scroll flow passage in the connection region is a first cross-section, the turning start point on the first cross-section is a first turning start point, a turning end point on the first cross-section is a first turning end point, and a tangent line to the first inner circumferential surface passing through the first turning start point on the first cross-section is a first direction, the first turning start point exists at a position away from the first turning end point along the first direction by a distance not less than 30% of a height dimension along an axial direction of the centrifugal compressor at a minimum cross-sectional area position of the scroll flow passage.

A scroll structure of a centrifugal compressor includes, of a flow passage connection section where a scroll start portion and a scroll end portion of a scroll flow passage intersect, a connection region where a first inner circumferential surface of the scroll end portion in the centrifugal compressor and a second inner circumferential surface of the scroll start portion in the centrifugal compressor are connected. The connection region includes a turning start point where a direction starts to change from the first inner circumferential surface toward the second inner circumferential surface, and a turning end point where the change in direction from the first inner circumferential surface toward the second inner circumferential surface comes to an end. Where a cross-section orthogonal to an extension direction of a center line of the scroll flow passage in the connection region is a first cross-section, the turning start point on the first cross-section is a first turning start point, a turning end point on the first cross-section is a first turning end point, and a tangent line to the first inner circumferential surface passing through the first turning start point on the first cross-section is a first direction, the first turning start point exists at a position away from the first turning end point along the first direction by a distance not less than 30% of a height dimension along an axial direction of the centrifugal compressor at a minimum cross-sectional area position of the scroll flow passage.

A variable capacity turbocharger includes a variable nozzle unit having a shroud-side ring in which a first bearing hole is provided, a hub-side ring in which a second bearing hole is provided, a nozzle flow path formed between the shroud-side ring and the hub-side ring, and a nozzle vane disposed in the nozzle flow path and supported by both the first bearing hole and the second bearing hole. A turbine housing having a scroll flow path is connected to the nozzle flow path, in which the first bearing hole penetrates the shroud-side ring and communicates with the scroll flow path through a gap between the shroud-side ring and the turbine housing. Additionally, an opening of the first bearing hole on the gap side is smaller than an opening of the first bearing hole on the nozzle flow path side.

A variable capacity turbocharger includes a variable nozzle unit having a shroud-side ring in which a first bearing hole is provided, a hub-side ring in which a second bearing hole is provided, a nozzle flow path formed between the shroud-side ring and the hub-side ring, and a nozzle vane disposed in the nozzle flow path and supported by both the first bearing hole and the second bearing hole. A turbine housing having a scroll flow path is connected to the nozzle flow path, in which the first bearing hole penetrates the shroud-side ring and communicates with the scroll flow path through a gap between the shroud-side ring and the turbine housing. Additionally, an opening of the first bearing hole on the gap side is smaller than an opening of the first bearing hole on the nozzle flow path side.

In a compressor, a scroll includes a winding end portion, a discharge potion connected to the winding end portion, a winding start portion connected to the discharge potion, and a flow passage inner surface and when a projection plane is assumed for the scroll in a case in which a viewing point is located on a rotation axis of a compressor impeller and on a fluid suction side, and the flow passage inner surface on the projection plane includes a curved protrusion portion protruding outward in relation to the reference line.

An impeller back surface cooling structure for cooling a back surface of a compressor impeller of a supercharger includes: a first member facing a back surface of a compressor impeller via a gap; and a second member extending in a circumferential direction of the compressor impeller and forming, between the first member and the second member, a cooling passage through which a cooling medium being a liquid flows.

An impeller back surface cooling structure for cooling a back surface of a compressor impeller of a supercharger includes: a first member facing a back surface of a compressor impeller via a gap; and a second member extending in a circumferential direction of the compressor impeller and forming, between the first member and the second member, a cooling passage through which a cooling medium being a liquid flows.

A turbocharger includes a compressor housing, a turbine housing, a bearing housing, a variable nozzle unit, and a fixing member. The variable nozzle unit includes a first plate, a second plate, a plurality of nozzle vanes, and an attitude changing mechanism. The fixing member includes an engagement portion that is engaged with at least one of the first plate and the second plate, a through shaft portion shaped to extend through the bearing housing toward the compressor housing, and a fixing portion that fixes an end portion of the through shaft portion on the compressor housing side to the hearing housing.

A turbocharger for an internal combustion engine is provided. The turbocharger includes at least three connections for respective lines. The at least three connections are arranged on the same side of the turbocharger. The turbocharger is designed in such a manner that the lines can be mounted with a common screw to the at least three connections.

Provided is a supercharger (11) comprising: a hollow housing (15); a rotating shaft (14) rotatably supported by the housing (15); a turbine (12) provided at one axial end of the rotating shaft (14); and a compressor (13) provided at the other axial end of the rotating shaft (14). A threaded section (41) and a circular column section (42) are axially arranged at the other end of the rotating shaft (14). A threaded hole (43) with which the threaded section (41) is engaged and a fitting hole (44) in which the circular column section (42) is fitted are axially arranged in the compressor (13). The axial length of the circular column section (42) and the fitting hole (44) is set to be greater than the axial length of the threaded section (41) and the threaded hole (43).