A turbocharger is provided with: a rotational shaft; a rolling bearing rotatably supporting the rotational shaft; an oil film damper disposed radially outward of an outer ring of the rolling bearing; and a housing having a first axial retaining portion and a second axial retaining portion, disposed adjacent to both ends of the oil film damper in the axial direction, respectively, for restricting movement of the outer ring in the axial direction. An axial end surface of the outer ring, or a facing surface of the first axial retaining portion or the second axial retaining portion facing the axial end surface of the outer ring has: a coefficient of static friction smaller than that of a portion of the housing excluding the first axial retaining portion and the second axial retaining portion; or has a recess where oil of the oil film damper can enter.

A flexible cartridge assembly can include a flexible shell that includes a flexible portion disposed between a compressor-side portion and a turbine-side portion, where the flexible portion includes a series of arc-shaped cutouts disposed axially along at least a portion of the flexible portion; a compressor-side bearing assembly; and a turbine-side bearing assembly.

A flexible cartridge assembly can include a flexible shell that includes a flexible portion disposed between a compressor-side portion and a turbine-side portion, where the flexible portion includes a series of arc-shaped cutouts disposed axially along at least a portion of the flexible portion; a compressor-side bearing assembly; and a turbine-side bearing assembly.

A bearing device for a turbocharger according to one embodiment of the present invention includes: a rotational shaft; a journal bearing device including a compressor-side journal bearing and a turbine-side journal bearing; a bearing housing including a compressor-side bearing supporting portion, a turbine-side bearing supporting portion, and a bearing housing main body; and a lubricant oil guide member extending along a circumference direction of the rotational shaft, at an outer circumference side of at least one of the compressor-side bearing supporting portion and the turbine-side bearing supporting portion. When a virtual line extending vertically downward from a rotational center CL of the rotational shaft is defined as a reference line VL in a state where an oil discharge port is orientated downward, the lubricant oil guide member extends from the reference line VL along the circumference direction toward each of one side and another side of the reference line VL over a predetermined angle θ about the rotational center CL of the rotational shaft.

A turbocharger according to an embodiment of the present invention includes a rotating shaft, a compressor, a turbine, a compressor-side floating bearing and a turbine-side floating bearing that rotatably support the rotating shaft, and a bearing housing that houses the compressor-side floating bearing and the turbine-side floating bearing, the bearing housing being internally provided with a turbine-side oil feeding passage through which oil to be fed to the turbine-side floating bearing flows and a compressor-side oil feeding passage through which oil to be fed to the compressor-side floating bearing flows. A ratio of an oil feeding pressure for oil at an outlet of the compressor-side oil feeding passage to an oil feeding pressure for oil at an outlet of the turbine-side oil feeding passage is configured to be higher than 1.0 and lower than 1.5.

A turbocharger according to an embodiment of the present invention includes a rotating shaft, a compressor, a turbine, a compressor-side floating bearing and a turbine-side floating bearing that rotatably support the rotating shaft, and a bearing housing that houses the compressor-side floating bearing and the turbine-side floating bearing, the bearing housing being internally provided with a turbine-side oil feeding passage through which oil to be fed to the turbine-side floating bearing flows and a compressor-side oil feeding passage through which oil to be fed to the compressor-side floating bearing flows. A ratio of an oil feeding pressure for oil at an outlet of the compressor-side oil feeding passage to an oil feeding pressure for oil at an outlet of the turbine-side oil feeding passage is configured to be higher than 1.0 and lower than 1.5.

An internal combustion engine, ICE, system, includes a turbocharger having a turbine and a compressor for compressing intake air and feeding the intake air to the ICE. A turbo turbine unit is disposed in an exhaust gas path downstream the turbocharger to receive exhaust gas from the turbocharger. The turbo turbine unit having a turbine wheel, a bearing housing defining an inside volume for containing lubrication oil, and a sealing arrangement positioned in the vicinity of the turbine wheel for preventing lubrication oil from escaping from the inside volume of the bearing housing to an exhaust duct of the turbo turbine unit. A buffer air conduit extends between a selected position at the compressor and a buffer air inlet of the turbo turbine unit. The buffer air inlet is in fluid communication with a buffer air channel inside the turbo turbine unit to direct buffer air to a position in-between axially opposite arranged annular sealing members to provide a counter-pressure against at least one of the annular sealing members.

A supercharger includes a rotor housing defining a pair of cylindrical chambers. A driving shaft bearing is to support a driving rotor shaft for rotation in the rotor housing. A driven shaft bearing is to support a driven rotor shaft for rotation in the rotor housing. An oil sump housing is to enclose a timing gear end of the rotor housing. A shaft seal is disposed between the rotor housing and each respective rotor shaft. The oil sump housing, the rotor housing and driving and driven shaft seals define a closed container for oil to lubricate the driving shaft bearing, the driven shaft bearing, a driving timing gear and a driven timing gear. The oil pools in the closed container and a top surface of the oil is spaced below the timing gears when the driving rotor shaft is in a vertical orientation.

A supercharger includes a rotor housing defining a pair of cylindrical chambers. A driving shaft bearing is to support a driving rotor shaft for rotation in the rotor housing. A driven shaft bearing is to support a driven rotor shaft for rotation in the rotor housing. An oil sump housing is to enclose a timing gear end of the rotor housing. A shaft seal is disposed between the rotor housing and each respective rotor shaft. The oil sump housing, the rotor housing and driving and driven shaft seals define a closed container for oil to lubricate the driving shaft bearing, the driven shaft bearing, a driving timing gear and a driven timing gear. The oil pools in the closed container and a top surface of the oil is spaced below the timing gears when the driving rotor shaft is in a vertical orientation.

A thrust bearing device is provided with: a rotational shaft; a collar member fitted to the rotational shaft and having a first thrust surface; and a thrust member having an insertion hole into which the rotational shaft is inserted and a second thrust surface which is disposed around the insertion hole and faces the first thrust surface of the collar member. The first thrust surface is configured to be inclined with respect to a plane perpendicular to an axis of the rotational shaft so that a distance between the first thrust surface and the second thrust surface periodically increases and decreases with rotation of the rotational shaft.