Rotary Device

This application is a continuation application of International Application No. PCT/JP2024/016786, filed on May 1, 2024, which claims priority to Japanese Patent Application No. 2023-079608 filed on May 12, 2023, the entire contents of which are incorporated herein by reference.

The present disclosure relates to a rotary device.

A rotary device such as a centrifugal compressor and a turbine may include a plurality of vanes in a flow path around an impeller. For example, Patent Literature 1 discloses a centrifugal compressor including a plurality of diffuser vanes. This centrifugal compressor includes a scroll, a diffuser ring, the plurality of diffuser vanes, and a bearing base. The diffuser vanes are formed monolithically with the diffuser ring. The diffuser ring faces the bearing base across the diffuser vanes. Furthermore, the diffuser ring is fixed to the scroll. An O-ring is inserted between the diffuser ring and the scroll. Stress of the O-ring presses the diffuser vanes against the bearing base. According to such a configuration, generation of gaps between the bearing base and the diffuser vanes due to deformation of the scroll is curbed.

Patent Literature 2 discloses a radial turbine including a plurality nozzle vanes. This radial turbine includes a pair of side walls facing each other, the plurality of nozzle vanes, and a flange. The nozzle vanes are fixed to the flange. The nozzle vanes and the flange are arranged between the pair of side walls. A seal plate is arranged between the flange and one of the side walls. The seal plate presses the nozzle vanes against the other side wall. According to such a configuration, gaps between the nozzle vanes and the side wall can be reduced.

Patent Literature 1: JP H01-91100 U

Patent Literature 2: JP S61-85503 A

In such a rotary device as described above, it is desirable to curb expansion of a gap between a radially-outermost part of an impeller and a shroud to curb a decrease in efficiency.

The present disclosure aims to provide a rotary device that can curb expansion of a gap between a radially-outermost part of an impeller and a shroud.

To solve the above problem, a rotary device according to one aspect of the present disclosure includes an impeller, a plurality of vanes that is located radially outside the impeller and that is arranged along a circumferential direction, a housing body that encloses the impeller, a shroud piece that is discrete from the housing body, the shroud piece including at least a part of a shroud that faces blade surfaces of the impeller and being in contact with or fixed to at least a part of each vane, a surface that faces the shroud piece across the plurality of vanes, and an elastic body that is arranged between the housing body and the shroud piece and that presses the shroud piece and the vanes toward the surface.

The elastic body may include a disc spring that is arranged around a central axis of the impeller, and the disc spring may be arranged radially outside a radially-outermost part of the impeller, and an inner edge of the disc spring may press the shroud piece.

Alternatively, the disc spring may be arranged radially inside the radially-outermost part of the impeller, and an outer edge of the disc spring may press the shroud piece.

Alternatively, the disc spring may overlap the radially-outermost part of the impeller in the radial direction, and one of the inner edge and the outer edge of the disc spring closer to the radially-outermost part of the impeller may press the shroud piece.

The shroud piece may be in contact with or fixed to the whole vane.

The shroud piece may end at a position between an innermost end and an outermost end of the vane in the radial direction.

According to the present disclosure, expansion of a gap between a radially-outermost part of an impeller and a shroud can be curbed.

Embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. Specific dimensions, materials, and numerical values described in the embodiments are merely examples for a better understanding, and do not limit the present disclosure unless otherwise specified. In this specification and the drawings, duplicate explanations are omitted for elements including substantially the same functions and configurations by assigning the same sign. Furthermore, elements not directly related to the present disclosure are omitted from the figures.

is a schematic cross-sectional view of a turbocharger TC including a centrifugal compressor (rotary device) Caccording to a first embodiment. In the present embodiment, a configuration of the rotary device according to the present disclosure is applied to a centrifugal compressor C. For example, the turbocharger TC is applied to an engine. The turbocharger TC includes a housing, a shaft, a turbine impeller, and a compressor impeller.

As described later, the turbine impellerand the compressor impellerare arranged concentrically with the shaft, and rotate integrally with the shaft. Accordingly, in the present disclosure, an axial direction, a radial direction, and a circumferential direction of the shaft, the turbine impeller, and the compressor impellermay simply be referred to as the “axial direction,” the “radial direction,” and the “circumferential direction,” respectively, unless otherwise specified. Furthermore, in the present disclosure, a central axis of the shaft, the turbine impeller, and the compressor impellermay simply be referred to as a “central axis” unless otherwise specified.

The housingincludes a bearing housing, a turbine housing, and a compressor housing. In the axial direction, one end of the bearing housingis connected to the turbine housingby fastenerssuch as bolts. In the axial direction, the other end of the bearing housingis connected to the compressor housingby fastenerssuch as bolts.

The bearing housingincludes a bearing hole. The bearing holeextends in the axial direction within the bearing housing. The bearing holeaccommodates bearingsand. The bearingsandrotatably support the shaft.

The turbine impelleris provided at a first end of the shaftin the axial direction. The turbine impelleris rotatably accommodated in the turbine housing. The compressor impelleris provided at a second end that is opposite to the first end of the shaftin the axial direction. The compressor impelleris rotatably accommodated in the compressor housing. The shaft, the turbine impeller, and the compressor impellerrotate integrally with each other.

The compressor housingincludes an intake openingat an end that is opposite to the bearing housingin the axial direction. The intake openingis connected to an air cleaner (not shown). The bearing housingand the compressor housingdefine a diffuser flow paththerebetween. The diffuser flow pathhas an annular shape. The diffuser flow pathis located radially outside the compressor impeller. The diffuser flow pathis connected to the intake openingvia the compressor impeller. The diffuser flow pathaccommodates a plurality of vanes. The vanesare arranged radially outside the compressor impeller. The plurality of vanesis arranged along the circumferential direction.

The compressor housingincludes a compressor scroll flow path. The compressor scroll flow pathis located radially outside the diffuser flow path. The compressor scroll flow pathis connected to the diffuser flow path. Furthermore, the compressor scroll flow pathis connected to an intake port of an engine (not shown).

The compressor housingincludes a shroud. The shroudis located radially outside the compressor impeller, and faces blade surfaces of the compressor impellerin the radial direction and in the axial direction. A gap is formed between the shroudand blades of the compressor impeller. The shroudhas a curved surface shape that expands radially outward as it moves away from the intake openingin the axial direction.

A part of the compressor housingis formed as a shroud piece. In the present embodiment, the remainder of the compressor housingis formed as a housing body. In another embodiment, the compressor housingmay further include other parts. The shroud pieceis discrete from the housing body. The shroud pieceis attached to the housing body(the shroud pieceand the housing bodywill be described in detail later).

In the compressor housing, as the compressor impellerrotates, fluid (e.g., air) is sucked into the compressor housingfrom the intake opening. The fluid is accelerated while passing through the compressor impeller. The fluid is pressurized in the diffuser flow pathand the compressor scroll flow path. The pressurized fluid flows out from an outlet (not shown), and is led to the intake port of the engine. As such, a part including the compressor housingand the compressor impellerfunctions as the centrifugal compressor C.

The turbine housingincludes an exhaust openingat an end that is opposite to the bearing housingin the axial direction. The exhaust openingis connected to an exhaust gas purifier (not shown). The turbine housingincludes a flow path. The flow pathhas an annular shape. The flow pathis located radially outside the turbine impeller. The flow pathis connected to the exhaust openingvia the turbine impeller.

The turbine housingincludes a turbine scroll flow path. The turbine scroll flow pathis located radially outside the flow path. The turbine scroll flow pathis connected to the flow path. Furthermore, the turbine scroll flow pathis connected to a gas inlet (not shown). The gas inlet receives exhaust gas discharged from an exhaust manifold of the engine (not shown).

In the turbine housing, the exhaust gas is led from the gas inlet to the turbine scroll flow path, and is further led to the exhaust openingvia the flow pathand the turbine impeller. The exhaust gas rotates the turbine impellerwhile passing through the turbine impeller.

Rotational force of the turbine impelleris transmitted to the compressor impellervia the shaft. As the compressor impellerrotates, the fluid is pressurized as described above. As such, the pressurized fluid is led to the intake port of the engine. Thus, a part including the turbine housingand the turbine impellerfunctions as a turbine T.

Next, the shroud pieceand the housing bodywill be described in detail.

is a schematic enlarged cross-sectional view of an area A in. As described above, the vanesare accommodated in the diffuser flow path. The diffuser flow pathis defined by a surface (first surface)and a surface (second surface). In the present disclosure, “define” may refer to determining a division or a boundary of a space such as a flow path or a clearance. The surfaceis formed on the compressor housing, and the surfaceis formed on the bearing housing. The surfaceis continuous with the shroud. The surfacefaces the surfacein the axial direction.

For example, the vaneis fixed to one of the surfacesand. For example, the vanemay be fixed to the surface. In this case, the vanecontacts the surface. In another embodiment, the vanemay be fixed to the surface. In this case, the vanecontacts the surface

The shroud pieceis located radially outside the impeller. The shroud pieceincludes at least a part of the shroud. The shroud piecealso includes at least a part of the surface. In other words, the shroud pieceextends over the shroudand the diffuser flow pathin the radial direction. In the present embodiment, the shroud pieceradially extends at least from the leading edge (innermost end) LE to the trailing edge (outermost end) TE of the vane. Referring to, more specifically, in the present embodiment, the shroud pieceincludes the entire shroud. Accordingly, the shroud pieceof the present embodiment serves as at least a part of the inner circumferential surface of the scroll. Furthermore, referring to, the shroud pieceextends radially outward beyond the trailing edge TE. In the present embodiment, the shroud pieceincludes the entire surface. The shroud pieceis fitted into the housing bodysuch that the shroud pieceand the vaneis allowed to be pressed against the surfaceby a disc spring(described later). Accordingly, a slight gap (not shown) may be provided between the shroud pieceand the housing body.

The compressor housingincludes an accommodation chamberbetween the shroud pieceand the housing body. In the present embodiment, the accommodation chamberhas an annular shape. The accommodation chamberis defined by surfacesandin the axial direction. Specifically, the shroud pieceincludes the surface, and the housing bodyincludes the surface. In the present embodiment, the surfacesandare perpendicular to the axial direction. The surfacesandare spaced apart from each other in the axial direction, and face each other in the axial direction.

The accommodation chamberaccommodates the disc spring (elastic body). The disc springhas a generally truncated conical shape. The disc springis arranged around the central axis of the compressor impeller. The disc springis arranged concentrically with the compressor impeller. The disc springis sandwiched between the surfacesand. The disc springincludes an inner edgeand an outer edge. In the present embodiment, the disc springis located radially outside the radially-outermost part of the compressor impeller. In this case, the inner edgeof the disc springis closest to the radially-outermost part of the compressor impellerin the radial direction. Accordingly, in the present embodiment, the disc springis arranged such that the inner edgecontacts the surfaceof the shroud pieceand the outer edgecontacts the surfaceof the housing body.

is a schematic enlarged cross-sectional view of a modified example. In this example, a centrifugal compressor Cdiffers from the above-described centrifugal compressor Cin the position of the disc spring. For other configurations, the centrifugal compressor Cmay be the same as the centrifugal compressor C. The disc springis located radially inside the radially-outermost part of the compressor impeller. In this case, the outer edgeof the disc springis closest to the radially-outermost part of the compressor impellerin the radial direction. Accordingly, the disc springis arranged such that the outer edgecontacts the surfaceof the shroud pieceand the inner edgecontacts the surfaceof the housing body.

is a schematic enlarged cross-sectional view of another modified example. In this example, the centrifugal compressor Cdiffers from the above-described centrifugal compressors Cand Cin the position of the disc spring. For other configurations, the centrifugal compressor Cmay be the same as the centrifugal compressors Cand C. The disc springoverlaps the radially-outermost part of the compressor impellerin the radial direction. In this case, the disc springis arranged such that one of the inner edgeand the outer edgecloser to the radially-outermost part of the compressor impellerpresses the surfaceof the shroud piece. In the example shown in, the outer edgeis closer to the radially-outermost part of the compressor impeller. Accordingly, the disc springis arranged such that the outer edgepresses the surfaceof the shroud piece.

According to the above-described configurations of the centrifugal compressors C, C, and C, a part of the shroud piececloser to the radially-outermost part of the compressor impellercan be pressed by the disc spring. Accordingly, expansion of the gap between the radially-outermost part of the compressor impellerand the shroudcan be further curbed. These configurations also apply to a centrifugal compressor Cof a second embodiment (described later). The orientation of the disc springmay be opposite to the above configurations. For example, in, the outer edgemay contact the surfaceof the shroud piece, and the inner edgemay contact the surfaceof the housing body. In this case, the shroud piececan also be pressed toward the compressor impellerin the axial direction by the disc spring.

During assembly of the turbocharger TC, the disc springis placed in the accommodation chamberin a compressed state in the axial direction. A preload is applied to the disc spring. The inner edgeof the disc springpresses the shroud piecetoward the surfacein the axial direction. Accordingly, the shroud pieceis pressed toward the compressor impellerin the axial direction. The shroud pieceincludes at least a part of the shroud, specifically a part of the shroudthat faces the radially-outermost part of the compressor impellerin the axial direction. As a result, when the compressor housingundergoes thermal deformation due to high-temperature fluid, expansion of the gap between the shroudand the radially-outermost part of the compressor impelleris curbed. In addition, the inner edgeof the disc spring, together with the shroud piece, presses the vanestoward the surfacein the axial direction. Accordingly, expansion of the gaps between the vanesand the surfaceor the gaps between the vanesand the surfacecan be curbed. As such, a decrease in efficiency of the centrifugal compressor Cis curbed.

The centrifugal compressor Cas described above includes the compressor impeller, the plurality of vanesthat is located radially outside the compressor impellerand that is arranged along the circumferential direction, the housing bodythat encloses the compressor impeller, the shroud piecethat is discrete from the housing body, the shroud piece including at least a part of the shroudfacing the blade surfaces of the compressor impellerand being in contact with or fixed to at least a part of each vane, the surface (opposite surface)that faces the shroud pieceacross the plurality of vanes, and the disc springthat is arranged between the housing bodyand the shroud pieceand that presses the shroud pieceand the vanestoward the surface. According to such a configuration, the shroud pieceis pressed toward the compressor impellerin the axial direction by the disc spring, so that when the compressor housingundergoes thermal deformation, expansion of the gap between the shroudand the radially-outermost part of the compressor impelleris curbed. In addition, according to the above-described configuration, the vanesare pressed toward the surfaceby the disc springtogether with the shroud piece, so that expansion of the gaps between the vanesand the surfaceor the gaps between the vanesand the surfacecan be curbed. Accordingly, a decrease in efficiency of the centrifugal compressor Cis curbed.

Furthermore, in the centrifugal compressor C, the shroud pieceis in contact with or fixed to the whole vane. According to such a configuration, the whole vaneis pressed by the shroud piece. Accordingly, local distortion of the vanecan be reduced.

Furthermore, in the centrifugal compressor C, the elastic body includes the disc springarranged around the central axis of the compressor impeller, the disc springis arranged radially outside the radially-outermost part of the compressor impeller, and the inner edgeof the disc springpresses the shroud piece. Furthermore, in the centrifugal compressor C, the disc springis arranged radially inside the radially-outermost part of the compressor impeller, and the outer edgeof the disc springpresses the shroud piece. In addition, in the centrifugal compressor C, the disc springoverlaps the radially-outermost part of the compressor impellerin the radial direction, and one of the inner edgeand the outer edgecloser to the radially-outermost part of the compressor impellerpresses the shroud piece. With these configurations, a part of the shroud piececloser to the radially-outermost part of the compressor impellercan be pressed by the disc spring. Accordingly, expansion of the gap between the radially-outermost part of the compressor impellerand the shroudcan be further curbed.

Next, another embodiment will be described.

is a schematic cross-sectional view of the turbocharger TC including a centrifugal compressor Caccording to a second embodiment. The centrifugal compressor Cdiffers from the centrifugal compressor Caccording to the first embodiment in the shape of the shroud piece. For other configurations, the centrifugal compressor Cmay be the same as the centrifugal compressor C.

is a schematic enlarged cross-sectional view of area B in. In the present embodiment, the shroud pieceends at a position P between the leading edge LE and the trailing edge TE in the radial direction. Referring to, specifically, in the present embodiment, the shroud pieceincludes an area from a part parallel to the central axis in the shroud, to the position P between the leading edge LE and the trailing edge TE. Referring to, in the present embodiment, the shroud piecedoes not include a part radially side the position P in the surface

Referring to, in the centrifugal compressor Caccording to the first embodiment, since the shroud pieceextends radially longer, an upstream boundary W and a downstream boundary X between the shroud pieceand the housing bodyare relatively separated. In contrast, referring to, in the centrifugal compressor Caccording to the second embodiment, since the shroud pieceis shorter in the radial direction, the upstream boundary Y and the downstream boundary Z between the shroud pieceand the housing bodyare relatively close to each other. According to such a configuration, a pressure difference between the boundary Y and the boundary Z can be reduced, and fluid leakage can be reduced.

The centrifugal compressor Cas described above has substantially the same effects as the centrifugal compressor Caccording to the first embodiment. Furthermore, in the centrifugal compressor C, the shroud pieceends at the position P between the leading edge LE and the trailing edge TE in the radial direction. According to such a configuration, the shroud pieceis shorter in the radial direction, thereby reducing the pressure difference between the boundary Y and the boundary Z and reducing fluid leakage, as described above.

Although the embodiments of the present disclosure have been described above with reference to the accompanying drawings, the present disclosure is not limited thereto. It is obvious that a person skilled in the art can conceive of various examples of variations or modifications within the scope of the claims, which are also understood to belong to the technical scope of the present disclosure.

For example, in the above embodiments, the disc spring is used as the elastic body. In another embodiment, various elastic bodies such as a coil spring or a heat-resistant resin may be used.