Turbine wheel

Abstract

To provide a turbine wheel that can suppress generation of a vortex on a negative pressure surface side of each turbine blade while securing rigidity at an inflow-side edge portion of each turbine blade.SOLUTION: A turbine wheel 1 includes a hub 100 and a plurality of turbine blades 200. Each turbine blade 200 includes a hub-side edge portion 201, a shroud-side edge portion 202, an inflow-side edge portion 203, and an outflow-side edge portion 204. An inlet region 210 of each turbine blade 200 includes an inlet portion 212, and a thickness reduction portion 214, which gradually decreases in thickness toward the outflow-side edge portion 204. A thickness of the inlet portion 212 is constant toward the outflow-side edge portion 204 or gradually increases toward the outflow-side edge portion 204. The thickness reduction portion 214 is formed such that a ratio of a length from the inflow-side edge portion 203 to a length between the inflow-side edge portion 203 and the outflow-side edge portion 204 is within a range of 0.3 or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This disclosure relates to a turbine wheel.

Background Art

[0002] Japanese Unexamined Patent Application Publication No. 2020-79577 discloses a turbine wheel used in a turbocharger. The turbine wheel has a hub rotatable around a rotation axis and a plurality of turbine blades connected to the hub. An additional process is applied to a region including the outer edge in the radial direction and extending in a direction parallel to the rotation axis on the negative pressure surface of each turbine blade.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a turbine wheel as described in Japanese Unexamined Patent Application Publication No. 2020-79577, there is a need to suppress the generation of vortices on the negative pressure surface side of each turbine blade while ensuring the rigidity of the inflow side edge formed on the gas inflow side of each turbine blade.

[0005] An object of the present invention is to provide a turbine wheel capable of suppressing the generation of vortices on the negative pressure surface side of each turbine blade while ensuring the rigidity of the inflow side edge of each turbine blade.

Means for Solving the Problems

[0006] A turbine wheel according to one aspect of this disclosure comprises a hub that rotates around a rotation axis and a plurality of turbine blades connected to the hub, each of the plurality of turbine blades including a hub-side edge connected to the hub, a shroud-side edge facing a shroud housing the turbine wheel, an inlet-side edge formed on the gas inlet side, and an outlet-side edge formed on the gas outlet side, each of the turbine blades having an inlet region including the inlet-side edge, the inlet region including the inlet-side edge and extending from the hub-side edge to the shroud-side edge The turbine blade includes an inlet portion having an elongated shape, and a thickness reduction portion connected to the downstream end of the inlet portion in the direction from the inlet side edge toward the outlet side edge, wherein the thickness of the inlet portion is constant toward the outlet side edge, or gradually increases toward the outlet side edge, and the thickness reduction portion is formed in a range where the ratio of the length from the inlet side edge in the meridional plane to the length between the inlet side edge and the outlet side edge in the meridional plane of the turbine blade is 0.3 or less. [Effects of the Invention]

[0007] According to this disclosure, it is possible to provide a turbine wheel that can suppress the generation of vortices on the negative pressure side of each turbine blade while ensuring rigidity at the inlet side edge of each turbine blade. [Brief explanation of the drawing]

[0008] [Figure 1] This is a perspective view of a turbine wheel in a first embodiment of the present disclosure. [Figure 2] Figure 1 is a front view of the turbine wheel. [Figure 3] Figure 1 is a plan view of the turbine wheel. [Figure 4] Figure 3 shows a cross-sectional view along line IV-IV. [Figure 5] This is a schematic diagram of a turbine blade. [Figure 6] This graph shows the relationship between dimensionless length and dimensionless wing thickness in the meridional plane. [Figure 7] This is a cross-sectional view of the hub's side edge. [Figure 8] This is a front view of the side edge of the shroud. [Figure 9] This is a cross-sectional view of the central part between the hub side edge and the shroud side edge. [Figure 10] This is a perspective view of a turbine wheel in a second embodiment of the present disclosure. [Figure 11] Figure 10 is a front view of the turbine wheel. [Figure 12] Figure 10 is a plan view of the turbine wheel. [Figure 13] This is a cross-sectional view of the hub's side edge. [Figure 14] This is a front view of the side edge of the shroud. [Figure 15] This is a cross-sectional view of the area between the hub side edge and the shroud side edge. [Modes for carrying out the invention]

[0009] Embodiments of this invention will be described with reference to the drawings. In the drawings referred to below, the same or equivalent components are given the same numbers.

[0010] (First Embodiment) Figure 1 is a perspective view of a turbine wheel in a first embodiment of the present disclosure. Figure 2 is a front view of the turbine wheel shown in Figure 1. Figure 3 is a plan view of the turbine wheel shown in Figure 1. Figure 4 is a cross-sectional view taken along line IV-IV in Figure 3.

[0011] The turbine wheel 1 in this embodiment is preferably used in a turbocharger mounted on a vehicle. The turbine wheel 1 is made of, for example, a TiAl alloy. The turbine wheel 1 is manufactured by applying additional processing (cutting or electrolytic processing) to a raw material formed by casting. The raw material may be formed by forging or the like.

[0012] As shown in FIGS. 1 to 4, the turbine wheel 1 includes a hub 100 and a plurality of turbine blades 200.

[0013] The hub 100 is rotatable about the rotation axis AX. The hub 100 includes a portion that gradually increases in diameter from one side (the upper side in FIGS. 1, 2, and 4) in the rotation axis direction to the other side (the lower side in FIGS. 1, 2, and 4).

[0014] Each turbine blade 200 is connected to the hub 100. Each turbine blade 200 has a pressure surface (concave surface) and a suction surface (convex surface). In the present embodiment, additional processing is performed on at least a part of the suction surface (the surface that curves so as to be convex in the rotation direction of the hub 100) of each turbine blade 200. The surface of the turbine blade 200 where no additional processing is performed is constituted by a casting surface S1 formed from the as-cast surface. The surface of the turbine blade 200 where additional processing is performed is constituted by a processed surface S2 having a surface state different from that of the casting surface S1. The boundary between the casting surface S1 and the processed surface S2 is smoothly connected.

[0015] Each turbine blade 200 has a hub-side edge portion 201, a shroud-side edge portion 202, an inflow-side edge portion 203, and an outflow-side edge portion 204.

[0016] The hub-side edge portion 201 is connected to the hub 100. The hub-side edge portion 201 is constituted by an end face connected to the hub 100.

[0017] The shroud-side edge portion 202 faces a shroud (not shown) that houses the turbine wheel 1. The shroud-side edge portion 202 is constituted by an end face of the turbine blade 200.

[0018] The inlet side edge (leading edge) 203 is formed on the gas inlet side. The inlet side edge 203 connects the outer end of the hub side edge 201 in the radial direction of the hub 100 to the outer end of the shroud side edge 202 in the radial direction. In other words, the inlet side edge 203 connects the other end of the hub side edge 201 in the direction parallel to the rotation axis AX (the lower side in Figures 1, 2, and 4) to the other end of the shroud side edge 202 in the direction parallel to the rotation axis AX.

[0019] The trailing edge 204 is formed on the gas outlet side. The trailing edge 204 connects the inner end of the hub edge 201 in the radial direction to the inner end of the shroud edge 202 in the radial direction. In other words, the trailing edge 204 connects the aforementioned end of the hub edge 201 (the upper side in Figures 1, 2, and 4) in a direction parallel to the rotation axis AX to the aforementioned end of the shroud edge 202 in a direction parallel to the rotation axis AX. As shown in Figures 2 and 4, the trailing edge 204 may be approximately perpendicular to the rotation axis AX.

[0020] Each turbine blade 200 has an inlet region 210 including an inlet side edge 203. The inlet region 210 has an inlet portion 212 and a thickness reduction portion 214. In Figures 1 and 4, the inlet portion 212 is shown with a dot pattern, and the thickness reduction portion 214 is shown with diagonal lines.

[0021] The inlet portion 212 includes an inlet side edge portion 203. The inlet portion 212 has a shape that extends from the hub side edge portion 201 to the shroud side edge portion 202. The inlet portion 212 has a constant thickness toward the outlet side edge portion 204, or its thickness gradually increases toward the outlet side edge portion 204.

[0022] The thickness reduction section 214 is a region in which the thickness gradually decreases as it approaches the outlet edge 204. The thickness reduction section 214 is connected to the downstream end of the inlet section 212 in the direction from the inlet edge 203 toward the outlet edge 204 (gas flow direction). As shown in Figures 5 and 6, in this embodiment, the thickness reduction section 214 includes a region of each turbine blade 200 from the shroud edge 202 toward the central part between the hub edge 201 and the shroud edge 202.

[0023] As shown in Figures 5 and 6, the thickness reduction portion 214 is formed in a range where the dimensionless length S in the meridian plane is 0.3 or less. The dimensionless length S in the meridian plane refers to the ratio of the length from the inlet edge 203 along the meridian to the length between the inlet edge 203 and the outlet edge 204 of the turbine blade 200 along the meridian. In other words, the thickness reduction portion 214 is formed in a range between the inlet edge 203 and the outlet edge 204, and a portion that is 0.3 times the length between the inlet edge 203 and the outlet edge 204 along the meridian, extending from the inlet edge 203 toward the outlet edge 204. Furthermore, the dimensionless blade thickness refers to the thickness in the portion between the inlet edge 203 and the outlet edge 204 extending along a predetermined meridian, relative to the maximum thickness in the portion between the inlet edge 203 and the outlet edge 204 extending along a predetermined meridian.

[0024] In Figure 5, the total length of the meridian of the hub edge 201 is shown as Lh, the total length of the meridian of the shroud edge 202 is shown as Ls, and the total length of the meridian at the center between the hub edge 201 and the shroud edge 202 is shown as Lm. In Figure 5, the position corresponding to the meridian of the hub edge 201 is 0% span, the position corresponding to the meridian of the shroud edge 202 is 100% span, and the meridian at the center between the hub edge 201 and the shroud edge 202 is 50% span.

[0025] Furthermore, in Figure 5, the position where the dimensionless length S along the meridian is 0.3 is indicated by a dashed line A. This dashed line A connects the position of the hub side edge 201, where the length h1 is 0.3 times the total length Lh of the meridian of the hub side edge 201, from the upstream end to the downstream end, and the position of the shroud side edge 202, where the length s1 is 0.3 times the total length Ls of the meridian of the shroud side edge 202, from the upstream end to the downstream end.

[0026] Figure 7 is a cross-sectional view of the hub side edge. Figure 8 is a cross-sectional view of the shroud side edge. Figure 9 is a cross-sectional view of the central part between the hub side edge and the shroud side edge.

[0027] As shown in Figure 8, the inlet region 210 has a first curved surface 231, a second curved surface 232, and a connecting surface 233. The first curved surface 231, the second curved surface 232, and the connecting surface 233 are formed on the negative pressure surface of the turbine blade 200.

[0028] The first curved surface 231 is connected to the inlet side edge 203. The first curved surface 231 constitutes a part of the inlet portion 212. The first curved surface 231 is curved so as to be convex in the direction from the positive pressure surface to the negative pressure surface of the turbine blade 200 (the rotational direction of the hub 100).

[0029] The second curved surface 232 is formed at a position spaced apart from the first curved surface 231 in a direction along the camber line. The second curved surface 232 is curved so as to be convex in the direction from the positive pressure surface to the negative pressure surface of the turbine blade 200.

[0030] The connecting surface 233 connects the first curved surface 231 and the second curved surface 232. The connecting surface 233 constitutes a part of the thickness reduction portion 214. The connecting surface 233 is curved so as to be convex in the direction from the negative pressure surface to the positive pressure surface of the turbine blade 200.

[0031] The first curved surface 231, the second curved surface 232, and the connecting surface 233 are formed in the area between the central part of the hub side edge 201 and the shroud side edge 202 and the shroud side edge 202.

[0032] As described above, in the turbine wheel 1 of this embodiment, each turbine blade 200 has an inlet portion 212, so the rigidity of the inlet side edge portion 203 is ensured, and the thickness reduction portion 214 of each turbine blade 200 is formed in a range where the ratio (dimensionless length S in the meridional plane) is 0.3 or less, so the generation of vortices on the negative pressure side of each turbine blade 200 is suppressed.

[0033] (Second Embodiment) Next, the turbine wheel 1 in the second embodiment of this disclosure will be described with reference to Figures 10 to 15. In the second embodiment, only the parts that differ from the first embodiment will be described, and the same descriptions of structure, operation, and effects as in the first embodiment will not be repeated.

[0034] In this embodiment, the negative pressure surfaces of each turbine blade 200, specifically the areas near the inlet edge 203 and the shroud edge 202, and the area near the hub edge 201, are composed of unprocessed cast surfaces S1.

[0035] In this embodiment, as shown in Figure 15, for example, a thickness reduction portion 214 is formed in the central part between the hub side edge portion 201 and the shroud side edge portion 202.

[0036] In this embodiment, the rigidity of the inlet side edge 203 of each turbine blade 200 is effectively ensured compared to the turbine wheel 1 in the first embodiment.

[0037] The areas of each turbine blade 200 to be further machined are determined as appropriate, taking into account factors such as ensuring the rigidity of the inlet edge 203 and suppressing vortex generation by thinning the outlet edge 204.

[0038] Those skilled in the art will understand that the exemplary embodiments described above are specific examples of the following embodiments.

[0039] [Aspect 1] A hub that rotates around a rotation axis, A turbine wheel comprising a plurality of turbine blades connected to the hub, Each of the aforementioned plurality of turbine blades is The hub side edge portion connected to the hub, The shroud side edge facing the shroud that houses the turbine wheel, The inlet side edge formed on the gas inlet side, Including an outlet edge formed on the gas outlet side, Each of the turbine blades has an inlet region including the inlet side edge, The aforementioned entrance region is An inlet portion having a shape that includes the aforementioned inlet side edge and extends from the hub side edge to the shroud side edge, It includes a thickness reduction portion which is connected to the downstream end of the inlet portion in the direction from the inlet side edge toward the outlet side edge, and whose thickness gradually decreases toward the outlet side edge, The inlet portion has a constant thickness toward the outlet edge, or its thickness gradually increases toward the outlet edge. A turbine wheel in which the thickness reduction portion is formed in a range where the ratio of the length from the inlet side edge in the meridional plane to the length between the inlet side edge and the outlet side edge in the meridional plane of the turbine blade is 0.3 or less.

[0040] In this turbine wheel, each turbine blade has an inlet, ensuring rigidity at the inlet edge, and the thickness reduction portion of each turbine blade is formed within a range where the ratio is 0.3 or less, thereby suppressing the generation of vortices on the negative pressure side.

[0041] [Aspect 2] The aforementioned entrance region is A first curved surface, which is connected to the aforementioned inlet side edge and constitutes a part of the inlet portion, A second curved surface is formed at a position spaced apart from the first curved surface in a direction along the camber line of the turbine blade, It includes a connecting surface that connects the first curved surface and the second curved surface and constitutes a part of the thickness reduction portion, The first curved surface, the second curved surface, and the connecting surface are formed on the negative pressure surface of the turbine blade. The first curved surface and the second curved surface are curved such that they are convex in the direction from the positive pressure surface of the turbine blade toward the negative pressure surface. The turbine wheel according to embodiment 1, wherein the connecting surface is curved so as to be convex in the direction from the negative pressure surface to the positive pressure surface of the turbine blade.

[0042] [Aspect 3] The turbine wheel according to embodiment 2, wherein the first curved surface, the second curved surface, and the connecting surface are formed in the area between the central part of the hub side edge and the shroud side edge and the shroud side edge.

[0043] [Aspect 4] The surface of the aforementioned inlet is composed of a cast surface, The turbine wheel according to any one of embodiments 1 to 3, wherein the surface of the thickness reduction portion is composed of a machined surface having a surface condition different from that of the cast surface.

[0044] It should be noted that the embodiments disclosed herein are illustrative in all respects and not restrictive. The scope of the present invention is indicated by the claims rather than the description of the embodiments above, and further includes all modifications within the meaning and scope equivalent to the claims. [Explanation of symbols]

[0045] 1 Turbine wheel, 100 Hub, 200 Turbine blade, 201 Hub side edge, 202 Shroud side edge, 203 Inlet side edge, 204 Outlet side edge, 210 Inlet region, 212 Inlet section, 214 Thickness reduction section, 231 First curved section, 232 Second curved surface, 233 Connecting surface, S1 Cast surface, S2 Machined surface.

Claims

1. A hub that rotates around a rotation axis, A turbine wheel comprising a plurality of turbine blades connected to the hub, Each of the aforementioned plurality of turbine blades is The hub side edge portion connected to the hub, The shroud side edge facing the shroud that houses the turbine wheel, The inlet side edge formed on the gas inlet side, Including an outlet edge formed on the gas outlet side, Each of the turbine blades has an inlet region including the inlet side edge, The aforementioned entrance region is An inlet portion having a shape that includes the aforementioned inlet side edge and extends from the hub side edge to the shroud side edge, It includes a thickness reduction portion which is connected to the downstream end of the inlet portion in the direction from the inlet side edge toward the outlet side edge, and whose thickness gradually decreases toward the outlet side edge, The inlet portion has a constant thickness toward the outlet edge, or its thickness gradually increases toward the outlet edge. A turbine wheel in which the thickness reduction portion is formed in a range where the ratio of the length from the inlet side edge in the meridional plane to the length between the inlet side edge and the outlet side edge in the meridional plane of the turbine blade is 0.3 or less.

2. The aforementioned entrance region is A first curved surface, which is connected to the aforementioned inlet side edge and constitutes a part of the inlet portion, A second curved surface is formed at a position spaced apart from the first curved surface in a direction along the camber line of the turbine blade, It includes a connecting surface that connects the first curved surface and the second curved surface and constitutes a part of the thickness reduction portion, The first curved surface, the second curved surface, and the connecting surface are formed on the negative pressure surface of the turbine blade. The first curved surface and the second curved surface are curved such that they are convex in the direction from the positive pressure surface of the turbine blade toward the negative pressure surface. The turbine wheel according to claim 1, wherein the connecting surface is curved so as to be convex in the direction from the negative pressure surface to the positive pressure surface of the turbine blade.

3. The turbine wheel according to claim 2, wherein the first curved surface, the second curved surface, and the connecting surface are formed in the area between the central part of the hub side edge and the shroud side edge and the shroud side edge.

4. The surface of the aforementioned inlet is composed of a cast surface, The turbine wheel according to any one of claims 1 to 3, wherein the surface of the thickness reduction portion is composed of a machined surface having a surface condition different from that of the cast surface.

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