A turbocharger rotor shaft assembly and associated turbocharger that includes at least one turbine rotor member having a first face and an opposed second face; and a rotor shaft having a first end and an opposed second end distal from the first end, wherein the rotor shaft is connected to the at least one turbine rotor at a location proximate to the first end and projects outward therefrom, the rotor shaft having an outwardly oriented face and an interior chamber defined therein, the interior chamber having an interior chamber volume. The turbocharger rotor shaft also includes at least one thermal transfer material contained in the interior chamber of the rotor shaft that has a thermal conductivity value that is greater than the thermal conductivity value of the material of construction of the rotor shaft.

An object of the present invention is to provide a bearing structure of a turbocharger that can prevent generation of unusual noise and a decrease in operation efficiency and that can reduce manufacturing costs. The bearing structure of a turbocharger to accomplish such an object, includes a rotor shaft, a ball bearing, a retainer, and a housing. The rotor shaft is provided with a turbine impeller mounted on a first end and a compressor impeller mounted on a second end.

The ball bearing includes an inner ring and an outer ring that are supported in relatively rotatable manner. The retainer holds the outer ring. Between the inner ring and an outer peripheral surface of the rotor shaft, oil in a film state is interposed to form an oil film damper.

A variable nozzle unit in a variable-capacity supercharger includes: a first nozzle ring disposed in a turbine housing and formed with a plurality of first support holes; a second nozzle ring disposed to face the first nozzle ring and formed with a plurality of second support holes that are through-holes corresponding to the first support holes; a plurality of variable nozzles supported rotatably by the first and second nozzle rings; and a plurality of seal members disposed between a turbine scroll channel and a turbine wheel side. The variable nozzles include first nozzle shafts that are rotatably supported by the first support holes, and second nozzle shafts are rotatably supported by the second support holes, and a first seal member included in the plurality of seal members is provided at the turbine wheel side relative to the second support holes.

There is provided a turbocharger bearing housing having no necessity to use a core and capable of achieving cost reduction. A bearing housing of a turbocharger contains a shaft connecting a turbine and a compressor and turnably supports the shaft. The bearing housing of the turbocharger is divided into a turbine-side housing disposed at a turbine side and a compressor-side housing disposed at a compressor side. The turbine-side housing and the compressor-side housing is subjected to machining to thereby form a cooling water passage for supplying cooling water and a lubricating oil passage for supplying lubricating oil.

A turbocharger includes a turbine housing adapted to be arranged in the middle of an engine exhaust passage, a bearing housing coupled to the turbine housing, a turbine wheel located inside the turbine housing, a rotary shaft that is connected to the turbine wheel and is rotationally supported by the bearing housing, and a cooling water passage that is provided inside the turbine housing. The cooling water passage is located around the turbine wheel. The turbine housing includes a first connection portion joined to the bearing housing, a second connection portion joined to a part of the engine exhaust passage located on a downstream side of the turbine housing, and a heat insulating portion located between the cooling water passage and at least one of the first connection portion and the second connection portion.

In a turbine housing of a twin entry type turbocharger, a first scroll chamber communicating with a first exhaust manifold, and a second scroll chamber communicating with a second exhaust manifold are provided. A surface area of the first exhaust manifold is configured to be larger than a surface area of the second exhaust manifold, and these exhaust manifolds are cooled by a cooling mechanism. In the turbine housing, a first and second cooling water passages are respectively provided to cover the first and second scroll chambers. An internal combustion engine includes a cooling device that causes cooling water to flow into the first and second cooling water passages, and the cooling device is configured so that a temperature of the cooling water that is introduced into the second cooling water passage becomes lower than a temperature of cooling water that is introduced into the first cooling water passage.

An object is to provide an axial flow turbine of radial-inflow type whereby it is possible to suppress a decrease in turbine efficiency due to tip leakage, and a turbocharger having the same. An axial flow turbine of radial-inflow type includes a housing having a scroll part for swirling working fluid flowing into the housing (40) along a circumferential direction of a rotation shaft and a bend part (52) for changing a flow direction of the working fluid flowing inwardly in the radial direction from the scroll part into a direction along the axial direction to direct the working fluid to turbine blades (30). The bend part includes a tip-side inner wall surface (60) of a bend shape at least in a region at an upstream side, in the axial direction, of a portion (36H) of a leading edge (36) of the turbine blades, the portion being adjacent to a hub. The bend shape of the tip-side inner wall surface along the axial direction has a minimum curvature radius R.sub.min at a position X.sub.Z near the turbine blades, and a curvature radius R (>R.sub.min) at the upstream side of the position X.sub.Z.

An object is to provide an axial flow turbine of radial-inflow type whereby it is possible to suppress a decrease in turbine efficiency due to tip leakage, and a turbocharger having the same. An axial flow turbine of radial-inflow type includes a housing having a scroll part for swirling working fluid flowing into the housing (40) along a circumferential direction of a rotation shaft and a bend part (52) for changing a flow direction of the working fluid flowing inwardly in the radial direction from the scroll part into a direction along the axial direction to direct the working fluid to turbine blades (30). The bend part includes a tip-side inner wall surface (60) of a bend shape at least in a region at an upstream side, in the axial direction, of a portion (36H) of a leading edge (36) of the turbine blades, the portion being adjacent to a hub. The bend shape of the tip-side inner wall surface along the axial direction has a minimum curvature radius R.sub.min at a position X.sub.Z near the turbine blades, and a curvature radius R (>R.sub.min) at the upstream side of the position X.sub.Z.

An engine system is provided, which includes an engine, a swirl control valve, and a controller. The engine includes a cylinder, a piston, and a fuel injection valve provided incliningly with respect to an axial direction of the piston and configured to directly inject fuel into the cylinder. The swirl control valve is provided inside an intake passage and generates a swirl flow inside the cylinder at least when the valve closes. When an engine load is below a given threshold, the controller controls the swirl control valve to close, and controls the fuel injection valve to inject fuel during an intake stroke. While the engine load is below the threshold, at a fixed engine speed, the controller controls to advance a fuel injection timing when the engine load is at a first load, compared with at a second load higher than the first load.

A turbine housing has: a first inner member; a second inner member contacting with the first inner member; a turbine scroll flow path enclosed and defined by the first inner member and the second inner member; a first casting housing covering the first inner member at a side opposite to the second inner member; a second casting housing covering the second inner member at a side opposite to the first inner member; an aperture formed in one or both of the first casting housing and the second casting housing and including an opening that opens to an outside; a tube member arranged in the aperture and defining an inlet flow path connected to the turbine scroll flow path; and an inner opening defined by the first inner member and the second inner member and overlapping with one end of the tube member.