An exhaust-gas turbocharger for an internal combustion engine has a turbine housing, in which a turbine wheel with a shaft is arranged rotatably. The shaft is mounted rotatably in a bearing housing via at least one piston ring adjacently with respect to the turbine wheel. The bearing housing has a lubricant inflow and a pressureless lubricant outflow for lubricating the shaft, wherein an insulating washer is provided which is clamped in by the turbine housing and the bearing housing and has an opening which is connected to the lubricant outflow in a manner which conducts a lubricant. Passage of lubricant out of the bearing housing into the turbine housing is avoided.

Different attack angles including a first attack angle and a second attack angle are set to turbine blades on a first axial side and a second axial side according to respective relative inflow angles of an exhaust gas. In other words, the first attack angle is set on the first axial side according to a relative inflow angle of an exhaust gas blown against the turbine blades through a first scroll passage, and the second attack angle is set on the second axial side according to a relative inflow angle of an exhaust gas blown against the turbine blades through a second scroll passage. An average value of the first attack angle is larger than an average value of the second attack angle.

Different attack angles including a first attack angle and a second attack angle are set to turbine blades on a first axial side and a second axial side according to respective relative inflow angles of an exhaust gas. In other words, the first attack angle is set on the first axial side according to a relative inflow angle of an exhaust gas blown against the turbine blades through a first scroll passage, and the second attack angle is set on the second axial side according to a relative inflow angle of an exhaust gas blown against the turbine blades through a second scroll passage. An average value of the first attack angle is larger than an average value of the second attack angle.

A bearing structure of a turbocharger includes a rotor shaft, two angular ball bearings, a retainer, a housing, and an oil film damper. Each of the angular ball bearings includes an inner ring and an outer ring that are supported in relatively rotatable manner. The rotor shaft is inserted into the inner ring. The retainer holds the outer ring. The housing houses therein the rotor shaft, the angular ball bearings, and the retainer to constitute a bearing housing. The oil film damper is formed of oil in a film state and is interposed between the inner ring and an outer peripheral surface of the rotor shaft. The inner ring is configured to rotate with rotation of the rotor shaft via the oil film damper.

A bearing structure of a turbocharger includes a rotor shaft, two angular ball bearings, a retainer, a housing, and an oil film damper. Each of the angular ball bearings includes an inner ring and an outer ring that are supported in relatively rotatable manner. The rotor shaft is inserted into the inner ring. The retainer holds the outer ring. The housing houses therein the rotor shaft, the angular ball bearings, and the retainer to constitute a bearing housing. The oil film damper is formed of oil in a film state and is interposed between the inner ring and an outer peripheral surface of the rotor shaft. The inner ring is configured to rotate with rotation of the rotor shaft via the oil film damper.

A turbo rotor includes a turbine wheel, a connection element and a rotor shaft. The turbine wheel has a plurality of blades, wherein a cavity is formed at a bottom of the turbine wheel, and at least one fixing structure is formed in the cavity. The connection element is accommodated in the cavity. The connection element includes a main body and at least one engaging structure formed on the main body, wherein the at least one engaging structure is engaged with the at least one fixing structure for preventing the connection element from moving along or rotating around a rotational axis of the turbo rotor relative to the turbine wheel. The rotor shaft is connected to the main body for supporting the turbine wheel.

An object is to provide a radial turbine blade that can reduce an impact loss of inflowing gas at a leading edge of the turbine blade and achieve a higher turbine efficiency, even in a case of a flow field corresponding to a low turbine operational velocity ratio U/C0 due to a throttling operation on a variable nozzle mechanism of a variable geometry turbocharger. In a radial turbine blade, a hub-side end portion Pa at a leading edge 51 of a turbine blade 50 is formed to be positioned more on a rear side in a rotation direction R of the turbine blade 50 than a shroud-side end portion Sc at the leading edge 51, and a straight line connecting between the shroud-side end portion Sc and the hub-side end portion Pa is inclined with respect to a straight line extending in a rotation axis direction from the shroud-side end portion Sc at the leading edge 51 onto a hub 17 surface by an angle in a range from 30° to 70° as viewed in the radial direction of the turbine blade 50.

An object is to provide a radial turbine blade that can reduce an impact loss of inflowing gas at a leading edge of the turbine blade and achieve a higher turbine efficiency, even in a case of a flow field corresponding to a low turbine operational velocity ratio U/C0 due to a throttling operation on a variable nozzle mechanism of a variable geometry turbocharger. In a radial turbine blade, a hub-side end portion Pa at a leading edge 51 of a turbine blade 50 is formed to be positioned more on a rear side in a rotation direction R of the turbine blade 50 than a shroud-side end portion Sc at the leading edge 51, and a straight line connecting between the shroud-side end portion Sc and the hub-side end portion Pa is inclined with respect to a straight line extending in a rotation axis direction from the shroud-side end portion Sc at the leading edge 51 onto a hub 17 surface by an angle in a range from 30° to 70° as viewed in the radial direction of the turbine blade 50.

The turbine rotor blade includes a platform with a first side and a second side; an airfoil extending from the first side of the platform; and an attachment portion extending from the second side of the platform. The attachment portion includes first and second side surfaces and a base surface on an underside of the attachment portion between the first and second side surface. The base surface includes at least one curved segment or angled segment.

The turbine rotor blade includes a platform with a first side and a second side; an airfoil extending from the first side of the platform; and an attachment portion extending from the second side of the platform. The attachment portion includes first and second side surfaces and a base surface on an underside of the attachment portion between the first and second side surface. The base surface includes at least one curved segment or angled segment.