ROTARY DEVICE

Description

CROSS REFERENCE TO RELATED APPLICATIONS

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.

BACKGROUND ART

Technical Field

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.

CITATION LIST

Patent Literature

Patent Literature 1: JP H01-91100 U

Patent Literature 2: JP S61-85503 A

SUMMARY

Technical Problem

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.

Solution to Problem

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.

Effects

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

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic cross-sectional view of a turbocharger including a centrifugal compressor according to a first embodiment.

FIG. 2 is a schematic enlarged cross-sectional view of area A in FIG. 1.

FIG. 3 is a schematic enlarged cross-sectional view of a modified example.

FIG. 4 is a schematic enlarged cross-sectional view of another modified example.

FIG. 5 is a schematic cross-sectional view of the turbocharger including a centrifugal compressor according to a second embodiment.

FIG. 6 is a schematic enlarged cross-sectional view of area B in FIG. 5.

DESCRIPTION OF EMBODIMENTS

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.

FIG. 1 is a schematic cross-sectional view of a turbocharger TC including a centrifugal compressor (rotary device) C1 according 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 C1. For example, the turbocharger TC is applied to an engine. The turbocharger TC includes a housing 1, a shaft 7, a turbine impeller 8, and a compressor impeller 9.

As described later, the turbine impeller 8 and the compressor impeller 9 are arranged concentrically with the shaft 7, and rotate integrally with the shaft 7. Accordingly, in the present disclosure, an axial direction, a radial direction, and a circumferential direction of the shaft 7, the turbine impeller 8, and the compressor impeller 9 may 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 7, the turbine impeller 8, and the compressor impeller 9 may simply be referred to as a “central axis” unless otherwise specified.

The housing 1 includes a bearing housing 2, a turbine housing 3, and a compressor housing 4. In the axial direction, one end of the bearing housing 2 is connected to the turbine housing 3 by fasteners 21a such as bolts. In the axial direction, the other end of the bearing housing 2 is connected to the compressor housing 4 by fasteners 21b such as bolts.

The bearing housing 2 includes a bearing hole 22. The bearing hole 22 extends in the axial direction within the bearing housing 2. The bearing hole 22 accommodates bearings 23 and 24. The bearings 23 and 24 rotatably support the shaft 7.

The turbine impeller 8 is provided at a first end of the shaft 7 in the axial direction. The turbine impeller 8 is rotatably accommodated in the turbine housing 3. The compressor impeller 9 is provided at a second end that is opposite to the first end of the shaft 7 in the axial direction. The compressor impeller 9 is rotatably accommodated in the compressor housing 4. The shaft 7, the turbine impeller 8, and the compressor impeller 9 rotate integrally with each other.

The compressor housing 4 includes an intake opening 10 at an end that is opposite to the bearing housing 2 in the axial direction. The intake opening 10 is connected to an air cleaner (not shown). The bearing housing 2 and the compressor housing 4 define a diffuser flow path 11 therebetween. The diffuser flow path 11 has an annular shape. The diffuser flow path 11 is located radially outside the compressor impeller 9. The diffuser flow path 11 is connected to the intake opening 10 via the compressor impeller 9. The diffuser flow path 11 accommodates a plurality of vanes 50. The vanes 50 are arranged radially outside the compressor impeller 9. The plurality of vanes 50 is arranged along the circumferential direction.

The compressor housing 4 includes a compressor scroll flow path 12. The compressor scroll flow path 12 is located radially outside the diffuser flow path 11. The compressor scroll flow path 12 is connected to the diffuser flow path 11. Furthermore, the compressor scroll flow path 12 is connected to an intake port of an engine (not shown).

The compressor housing 4 includes a shroud 41. The shroud 41 is located radially outside the compressor impeller 9, and faces blade surfaces of the compressor impeller 9 in the radial direction and in the axial direction. A gap is formed between the shroud 41 and blades of the compressor impeller 9. The shroud 41 has a curved surface shape that expands radially outward as it moves away from the intake opening 10 in the axial direction.

A part of the compressor housing 4 is formed as a shroud piece 42. In the present embodiment, the remainder of the compressor housing 4 is formed as a housing body 43. In another embodiment, the compressor housing 4 may further include other parts. The shroud piece 42 is discrete from the housing body 43. The shroud piece 42 is attached to the housing body 43 (the shroud piece 42 and the housing body 43 will be described in detail later).

In the compressor housing 4, as the compressor impeller 9 rotates, fluid (e.g., air) is sucked into the compressor housing 4 from the intake opening 10. The fluid is accelerated while passing through the compressor impeller 9. The fluid is pressurized in the diffuser flow path 11 and the compressor scroll flow path 12. 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 housing 4 and the compressor impeller 9 functions as the centrifugal compressor C1.

The turbine housing 3 includes an exhaust opening 13 at an end that is opposite to the bearing housing 2 in the axial direction. The exhaust opening 13 is connected to an exhaust gas purifier (not shown). The turbine housing 3 includes a flow path 14. The flow path 14 has an annular shape. The flow path 14 is located radially outside the turbine impeller 8. The flow path 14 is connected to the exhaust opening 13 via the turbine impeller 8.

The turbine housing 3 includes a turbine scroll flow path 15. The turbine scroll flow path 15 is located radially outside the flow path 14. The turbine scroll flow path 15 is connected to the flow path 14. Furthermore, the turbine scroll flow path 15 is 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 3, the exhaust gas is led from the gas inlet to the turbine scroll flow path 15, and is further led to the exhaust opening 13 via the flow path 14 and the turbine impeller 8. The exhaust gas rotates the turbine impeller 8 while passing through the turbine impeller 8.

Rotational force of the turbine impeller 8 is transmitted to the compressor impeller 9 via the shaft 7. As the compressor impeller 9 rotates, 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 housing 3 and the turbine impeller 8 functions as a turbine T.

Next, the shroud piece 42 and the housing body 43 will be described in detail.

FIG. 2 is a schematic enlarged cross-sectional view of an area A in FIG. 1. As described above, the vanes 50 are accommodated in the diffuser flow path 11. The diffuser flow path 11 is defined by a surface (first surface) 11a and a surface (second surface) 11b. 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 surface 11a is formed on the compressor housing 4, and the surface 11b is formed on the bearing housing 2. The surface 11a is continuous with the shroud 41. The surface 11b faces the surface 11a in the axial direction.

For example, the vane 50 is fixed to one of the surfaces 11a and 11b. For example, the vane 50 may be fixed to the surface 11a. In this case, the vane 50 contacts the surface 11b. In another embodiment, the vane 50 may be fixed to the surface 11b. In this case, the vane 50 contacts the surface 11a.

The shroud piece 42 is located radially outside the impeller 9. The shroud piece 42 includes at least a part of the shroud 41. The shroud piece 42 also includes at least a part of the surface 11a. In other words, the shroud piece 42 extends over the shroud 41 and the diffuser flow path 11 in the radial direction. In the present embodiment, the shroud piece 42 radially extends at least from the leading edge (innermost end) LE to the trailing edge (outermost end) TE of the vane 50. Referring to FIG. 1, more specifically, in the present embodiment, the shroud piece 42 includes the entire shroud 41. Accordingly, the shroud piece 42 of the present embodiment serves as at least a part of the inner circumferential surface of the scroll. Furthermore, referring to FIG. 2, the shroud piece 42 extends radially outward beyond the trailing edge TE. In the present embodiment, the shroud piece 42 includes the entire surface 11a. The shroud piece 42 is fitted into the housing body 43 such that the shroud piece 42 and the vane 50 is allowed to be pressed against the surface 11b by a disc spring 60 (described later). Accordingly, a slight gap (not shown) may be provided between the shroud piece 42 and the housing body 43.

The compressor housing 4 includes an accommodation chamber 44 between the shroud piece 42 and the housing body 43. In the present embodiment, the accommodation chamber 44 has an annular shape. The accommodation chamber 44 is defined by surfaces 44a and 44b in the axial direction. Specifically, the shroud piece 42 includes the surface 44a, and the housing body 43 includes the surface 44b. In the present embodiment, the surfaces 44a and 44b are perpendicular to the axial direction. The surfaces 44a and 44b are spaced apart from each other in the axial direction, and face each other in the axial direction.

The accommodation chamber 44 accommodates the disc spring (elastic body) 60. The disc spring 60 has a generally truncated conical shape. The disc spring 60 is arranged around the central axis of the compressor impeller 9. The disc spring 60 is arranged concentrically with the compressor impeller 9. The disc spring 60 is sandwiched between the surfaces 44a and 44b. The disc spring 60 includes an inner edge 60a and an outer edge 60b. In the present embodiment, the disc spring 60 is located radially outside the radially-outermost part of the compressor impeller 9. In this case, the inner edge 60a of the disc spring 60 is closest to the radially-outermost part of the compressor impeller 9 in the radial direction. Accordingly, in the present embodiment, the disc spring 60 is arranged such that the inner edge 60a contacts the surface 44a of the shroud piece 42 and the outer edge 60b contacts the surface 44b of the housing body 43.

FIG. 3 is a schematic enlarged cross-sectional view of a modified example. In this example, a centrifugal compressor C1a differs from the above-described centrifugal compressor C1 in the position of the disc spring 60. For other configurations, the centrifugal compressor C1a may be the same as the centrifugal compressor C1. The disc spring 60 is located radially inside the radially-outermost part of the compressor impeller 9. In this case, the outer edge 60b of the disc spring 60 is closest to the radially-outermost part of the compressor impeller 9 in the radial direction. Accordingly, the disc spring 60 is arranged such that the outer edge 60b contacts the surface 44a of the shroud piece 42 and the inner edge 60a contacts the surface 44b of the housing body 43.

FIG. 4 is a schematic enlarged cross-sectional view of another modified example. In this example, the centrifugal compressor C1b differs from the above-described centrifugal compressors C1 and C1a in the position of the disc spring 60. For other configurations, the centrifugal compressor C1b may be the same as the centrifugal compressors C1 and C1a. The disc spring 60 overlaps the radially-outermost part of the compressor impeller 9 in the radial direction. In this case, the disc spring 60 is arranged such that one of the inner edge 60a and the outer edge 60b closer to the radially-outermost part of the compressor impeller 9 presses the surface 44a of the shroud piece 42. In the example shown in FIG. 4, the outer edge 60b is closer to the radially-outermost part of the compressor impeller 9. Accordingly, the disc spring 60 is arranged such that the outer edge 60b presses the surface 44a of the shroud piece 42.

According to the above-described configurations of the centrifugal compressors C1, C1a, and C1b, a part of the shroud piece 42 closer to the radially-outermost part of the compressor impeller 9 can be pressed by the disc spring 60. Accordingly, expansion of the gap between the radially-outermost part of the compressor impeller 9 and the shroud 41 can be further curbed. These configurations also apply to a centrifugal compressor C2 of a second embodiment (described later). The orientation of the disc spring 60 may be opposite to the above configurations. For example, in FIG. 2, the outer edge 60b may contact the surface 44a of the shroud piece 42, and the inner edge 60a may contact the surface 44b of the housing body 43. In this case, the shroud piece 42 can also be pressed toward the compressor impeller 9 in the axial direction by the disc spring 60.

During assembly of the turbocharger TC, the disc spring 60 is placed in the accommodation chamber 44 in a compressed state in the axial direction. A preload is applied to the disc spring 60. The inner edge 60a of the disc spring 60 presses the shroud piece 42 toward the surface 11b in the axial direction. Accordingly, the shroud piece 42 is pressed toward the compressor impeller 9 in the axial direction. The shroud piece 42 includes at least a part of the shroud 41, specifically a part of the shroud 41 that faces the radially-outermost part of the compressor impeller 9 in the axial direction. As a result, when the compressor housing 4 undergoes thermal deformation due to high-temperature fluid, expansion of the gap between the shroud 41 and the radially-outermost part of the compressor impeller 9 is curbed. In addition, the inner edge 60a of the disc spring 60, together with the shroud piece 42, presses the vanes 50 toward the surface 11b in the axial direction. Accordingly, expansion of the gaps between the vanes 50 and the surface 11b or the gaps between the vanes 50 and the surface 11a can be curbed. As such, a decrease in efficiency of the centrifugal compressor C1 is curbed.

The centrifugal compressor C1 as described above includes the compressor impeller 9, the plurality of vanes 50 that is located radially outside the compressor impeller 9 and that is arranged along the circumferential direction, the housing body 43 that encloses the compressor impeller 9, the shroud piece 42 that is discrete from the housing body 43, the shroud piece including at least a part of the shroud 41 facing the blade surfaces of the compressor impeller 9 and being in contact with or fixed to at least a part of each vane 50, the surface (opposite surface) 11b that faces the shroud piece 42 across the plurality of vanes 50, and the disc spring 60 that is arranged between the housing body 43 and the shroud piece 42 and that presses the shroud piece 42 and the vanes 50 toward the surface 11b. According to such a configuration, the shroud piece 42 is pressed toward the compressor impeller 9 in the axial direction by the disc spring 60, so that when the compressor housing 4 undergoes thermal deformation, expansion of the gap between the shroud 41 and the radially-outermost part of the compressor impeller 9 is curbed. In addition, according to the above-described configuration, the vanes 50 are pressed toward the surface 11b by the disc spring 60 together with the shroud piece 42, so that expansion of the gaps between the vanes 50 and the surface 11b or the gaps between the vanes 50 and the surface 11a can be curbed. Accordingly, a decrease in efficiency of the centrifugal compressor C1 is curbed.

Furthermore, in the centrifugal compressor C1, the shroud piece 42 is in contact with or fixed to the whole vane 50. According to such a configuration, the whole vane 50 is pressed by the shroud piece 42. Accordingly, local distortion of the vane 50 can be reduced.

Furthermore, in the centrifugal compressor C1, the elastic body includes the disc spring 60 arranged around the central axis of the compressor impeller 9, the disc spring 60 is arranged radially outside the radially-outermost part of the compressor impeller 9, and the inner edge 60a of the disc spring 60 presses the shroud piece 42. Furthermore, in the centrifugal compressor C1a, the disc spring 60 is arranged radially inside the radially-outermost part of the compressor impeller 9, and the outer edge 60b of the disc spring 60 presses the shroud piece 42. In addition, in the centrifugal compressor C1b, the disc spring 60 overlaps the radially-outermost part of the compressor impeller 9 in the radial direction, and one of the inner edge 60a and the outer edge 60b closer to the radially-outermost part of the compressor impeller 9 presses the shroud piece 42. With these configurations, a part of the shroud piece 42 closer to the radially-outermost part of the compressor impeller 9 can be pressed by the disc spring 60. Accordingly, expansion of the gap between the radially-outermost part of the compressor impeller 9 and the shroud 41 can be further curbed.

Next, another embodiment will be described.

FIG. 5 is a schematic cross-sectional view of the turbocharger TC including a centrifugal compressor C2 according to a second embodiment. The centrifugal compressor C2 differs from the centrifugal compressor C1 according to the first embodiment in the shape of the shroud piece 42. For other configurations, the centrifugal compressor C2 may be the same as the centrifugal compressor C1.

FIG. 6 is a schematic enlarged cross-sectional view of area B in FIG. 5. In the present embodiment, the shroud piece 42 ends at a position P between the leading edge LE and the trailing edge TE in the radial direction. Referring to FIGS. 5 and 6, specifically, in the present embodiment, the shroud piece 42 includes an area from a part parallel to the central axis in the shroud 41, to the position P between the leading edge LE and the trailing edge TE. Referring to FIG. 6, in the present embodiment, the shroud piece 42 does not include a part radially side the position P in the surface 11a.

Referring to FIG. 1, in the centrifugal compressor C1 according to the first embodiment, since the shroud piece 42 extends radially longer, an upstream boundary W and a downstream boundary X between the shroud piece 42 and the housing body 43 are relatively separated. In contrast, referring to FIG. 5, in the centrifugal compressor C2 according to the second embodiment, since the shroud piece 42 is shorter in the radial direction, the upstream boundary Y and the downstream boundary Z between the shroud piece 42 and the housing body 43 are 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 C2 as described above has substantially the same effects as the centrifugal compressor C1 according to the first embodiment. Furthermore, in the centrifugal compressor C2, the shroud piece 42 ends 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 piece 42 is 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.

Furthermore, in the above embodiments, the rotary device of the present disclosure is applied to the centrifugal compressors C1 and C2. In another embodiment, for example, the turbine T may be provided with nozzle vanes (not shown) in the flow path 14, and the rotary device of the present disclosure may be applied to the turbine T including the turbine impeller 8, the nozzle vanes, and the turbine housing 3.