Abstract: A centrifugal compressor includes a housing that accommodates a wheel. The housing includes an air intake space formed on an entrance side of the wheel; a flow passage to guide fluid compressed by the wheel to the outside of the housing; a return flow passage opened on each wall surface of the air intake space and the flow passage to circulate a part of the fluid in the flow passage to the air intake space without passing through the wheel; and an introduction portion provided in the air intake space, and having an inner peripheral surface that forms a flow passage to guide the fluid from the outside of the housing to the wheel. A downstream end of the inner peripheral surface in a flowing direction of the fluid is located radially inward of the wall surface of the housing.

Abstract: An oil film damper of a bearing structure is located between facing surfaces of two bearings. The oil film damper includes two protrusions protruding inward in a radial direction from an inner circumferential surface of a main body portion, an oil guiding passage penetrating through from the protrusion to an outer circumferential surface of the main body portion and guiding a lubricating oil from the outer circumference of the main body portion to the bearing, an inclined surface provided on a side opposite to the adjacent surface adjacent to the bearing in the protrusion and having an inner diameter gradually increasing as the diameter is separate from the adjacent surface in the rotation axis direction of the shaft, and an oil discharge hole provided between the two protrusions of the main body portion and discharging the lubricating oil to an outside from an inside of the main body portion.

Abstract: An oil film damper of a bearing structure is located between facing surfaces of two bearings. The oil film damper includes two protrusions protruding inward in a radial direction from an inner circumferential surface of a main body portion, an oil guiding passage penetrating through from the protrusion to an outer circumferential surface of the main body portion and guiding a lubricating oil from the outer circumference of the main body portion to the bearing, an inclined surface provided on a side opposite to the adjacent surface adjacent to the bearing in the protrusion and having an inner diameter gradually increasing as the diameter is separate from the adjacent surface in the rotation axis direction of the shaft, and an oil discharge hole provided between the two protrusions of the main body portion and discharging the lubricating oil to an outside from an inside of the main body portion.

Abstract: A turbocharger includes an open-and-close mechanism which opens and closes a circulation hole through which an exhaust gas flows into a turbine housing or the exhaust gas flows out of the turbine housing. The open-and-close mechanism includes: a valve; and an attachment plate one end of which is fixed to the valve, and the other end of which is provided with an insertion hole through which a stem turnably supported by the turbine housing is inserted, and an exposure hole which communicates with the insertion hole to expose part of an outer peripheral surface of the stem. The diameter of the insertion hole is gradually smaller in a direction of insertion of the stem. The stem includes a tapered portion whose diameter is gradually smaller toward its tip end in the direction of insertion into the insertion hole.

Abstract: Provided is a recirculation valve that diverts some of the compressed air in a scroll section to an upstream side of the scroll section via a bypass conduit in an open state and sends the compressed air in the scroll section to a downstream side in a closed state, the recirculation valve including a valve body that is fittable in a branch hole in which the scroll section communicates with the bypass conduit, and an actuator that moves the valve body between the closed state where the valve body is fitted in the branch hole and the open state where the valve body is away from the branch hole, in which the valve body forms an inner surface along an inner wall of the scroll section in the closed state.

Abstract: A centrifugal compressor includes a housing that accommodates a wheel. The housing includes an air intake space formed on an entrance side of the wheel; a flow passage to guide fluid compressed by the wheel to the outside of the housing; a return flow passage opened on each wall surface of the air intake space and the flow passage to circulate a part of the fluid in the flow passage to the air intake space without passing through the wheel; and an introduction portion provided in the air intake space, and having an inner peripheral surface that forms a flow passage to guide the fluid from the outside of the housing to the wheel. A downstream end of the inner peripheral surface in a flowing direction of the fluid is located inside in the radial direction of a shaft than the wall surface of the housing.

Abstract: A turbocharger includes an open-and-close mechanism which opens and closes a circulation hole through which an exhaust gas flows into a turbine housing or the exhaust gas flows out of the turbine housing. The open-and-close mechanism includes: a valve; and an attachment plate one end of which is fixed to the valve, and the other end of which is provided with an insertion hole through which a stem turnably supported by the turbine housing is inserted, and an exposure hole which communicates with the insertion hole to expose part of an outer peripheral surface of the stem. The diameter of the insertion hole is gradually smaller in a direction of insertion of the stem. The stem includes a tapered portion whose diameter is gradually smaller toward its tip end in the direction of insertion into the insertion hole.

Abstract: In a waste gate valve, a coil spring being expandable and contractible in the axial direction of a valve shaft is provided between a washer and an attachment tongue in an axial direction of a valve shaft of a valve. The coil spring is made of a heat-resistant alloy or a ceramic. An annular guard wall is formed on a front surface of the attachment tongue by counter boring in such a way as to surround the coil spring.

Abstract: Provided is a bypass valve that diverts some of compressed air in a scroll section to an upstream side of the scroll section via a bypass conduit in an open state and sends the compressed air in the scroll section to a downstream side in a closed state, the bypass valve including a valve body that is fittable in a branch hole in which the scroll section communicates with the bypass conduit, and an actuator that moves the valve body between the closed state where the valve body is fitted in the branch hole and the open state where the valve body is away from the branch hole, in which the valve body forms an inner surface along an inner wall of the scroll section in the closed state.