Turbine

Abstract

A turbine (T) is provided with an impeller (2) and a housing (5). The housing (5) comprises: a housing outlet; a first scroll flow path (51) that is positioned on the outside of the impeller (2) in the radial direction and that guides a fluid to the impeller (2); and a second scroll flow path (52) that is located on the outside of the impeller (2) in the radial direction, is located further toward the housing outlet than the first scroll flow path (51) in the central axis direction, and guides a fluid to the impeller (2). The second scroll flow path (52) is inclined with respect to the radial direction in a cross-section parallel to and including the central axis so as to be away from the housing outlet in the direction of the central axis as the second scroll flow path approaches the impeller (2) in the radial direction. In the cross section, a region including the outlet (54) of the second scroll flow path (52) includes: a first portion (P1) having a linear shape parallel to the radial direction; and a second portion (P2) that has an R shape and is continuously formed radially outward with respect to the first portion (P1).

Description

Technical Field

[0001] The present invention relates to a turbine. This application claims the benefit of priority based on Japanese Patent Application No. 2022-176675 filed on November 2, 2022, and the contents thereof are incorporated herein by reference. Background Art

[0002] The turbine may include two scroll flow paths arranged along the central axis direction of the impeller. For example, Patent Document 1 discloses a twin scroll turbocharger including such a turbine. In Patent Document 1, the supercharging efficiency is improved by adjusting the shape of the outlet portion of the front volute.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2013-136993 Summary of the invention

[0006] Problems to be solved by the invention

[0007] In this technical field, it is desirable to further improve turbine efficiency.

[0008] An object of the present invention is to provide a turbine capable of improving the efficiency of the turbine.

[0009] Solutions to Solve Problems

[0010] In order to solve the above-mentioned problems, a turbine of one embodiment of the present invention comprises: an impeller; and a casing, which is a casing for accommodating the impeller, the casing including: a casing outlet, which is separated from the impeller in the direction of the central axis of the impeller and discharges the fluid that has passed through the impeller; a first vortex flow path, which is located on the outside of the impeller in the radial direction of the impeller and guides the fluid to the impeller; and a second vortex flow path, which is located on the outside of the impeller in the radial direction and is located closer to the casing outlet in the direction of the central axis relative to the first vortex flow path and guides the fluid to the impeller, the second vortex flow path is inclined relative to the radial direction in a cross section parallel to the central axis of the impeller and including the central axis in a manner that moves away from the casing outlet in the direction of the central axis as it approaches the impeller in the radial direction, and in the above-mentioned cross section, the area including the outlet of the second vortex flow path includes: a first part, which has a straight line shape parallel to the radial direction; and a second part, which has an R shape and is continuously formed radially outward relative to the first part.

[0011] The first part and the second part may also have a cast black skin.

[0012] The first scroll flow path and the second scroll flow path may be directly connected to the space accommodating the impeller.

[0013] Effects of the Invention

[0014] According to the present invention, the turbine efficiency can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic cross-sectional view of a supercharger including a turbine according to an embodiment.

[0016] Figure 2 Yes means Figure 1 An enlarged cross-sectional view of area A in FIG.

[0017] Figure 3 It is an enlarged cross-sectional view showing a turbine according to a first comparative example.

[0018] Figure 4 It is an enlarged cross-sectional view showing a turbine according to a second comparative example.

[0019] Figure 5 It is an enlarged cross-sectional view showing the analysis results of the entropy of the turbines according to the embodiment, the first comparative example, and the second comparative example.

[0020] Figure 6 It is a graph showing the analysis results of the turbine efficiency of the turbines according to the embodiment, the first comparative example, and the second comparative example. DETAILED DESCRIPTION

[0021] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The specific dimensions, materials, and numerical values ​​shown in the embodiments are merely examples for easy understanding and do not limit the present invention unless otherwise specified. In addition, in this specification and the accompanying drawings, for elements having substantially the same function and structure, repeated descriptions are omitted by marking the same symbols. In addition, elements that are not directly related to the present invention are omitted from the drawings.

[0022] Figure 1 It is a schematic cross-sectional view of a supercharger TC including a turbine T according to the embodiment. Figure 1 The cross section is parallel to and includes the central axes of the shaft 1, the turbine impeller 2, and the compressor impeller 3. In the present embodiment, the turbine T is assembled to the supercharger TC. In other embodiments, the turbine T may be assembled to a device other than the supercharger TC, or may be a single unit.

[0023] The supercharger TC includes a shaft 1, a turbine impeller (impeller) 2, and a compressor impeller 3. As described later, the shaft 1, the turbine impeller 2, and the compressor impeller 3 rotate integrally. Therefore, in the present invention, the "central axis direction", "radial direction", and "circumferential direction" of the shaft 1, the turbine impeller 2, and the compressor impeller 3 may be referred to as "central axis direction", "radial direction", and "circumferential direction", respectively.

[0024] The supercharger TC includes a bearing housing 4, a turbine housing (housing) 5, and a compressor housing 6. The turbine housing 5 is connected to a first end surface of the bearing housing 4 in the central axis direction, Figure 1 The compressor housing 6 is connected to the second end surface of the bearing housing 4 in the direction of the central axis. Figure 1 The middle is the right side end connection.

[0025] The bearing housing 4 includes a bearing hole 4a. The bearing hole 4a extends in the bearing housing 4 along the central axis direction. The bearing hole 4a accommodates the bearing 7. In this embodiment, as an example of the bearing 7, two fully floating bearings separated and arranged in the central axis direction are shown. In other embodiments, the bearing 7 may also be a semi-floating bearing or other radial bearings such as a rolling bearing. The bearing 7 rotatably supports the shaft 1.

[0026] The turbine impeller 2 is disposed at a first end portion of the shaft 1 in the central axis direction. Figure 1 The left end is in the middle. The turbine impeller 2 rotates integrally with the shaft 1. The turbine impeller 2 is rotatably accommodated in the turbine housing 5.

[0027] The compressor impeller 3 is provided at the second end of the shaft 1 on the opposite side to the first end in the central axis direction. Figure 1 The compressor impeller 3 rotates integrally with the shaft 1. The compressor impeller 3 is rotatably accommodated in the compressor housing 6.

[0028] The compressor housing 6 includes an air intake port 6a at an end surface on the side opposite to the bearing housing 4 in the central axis direction. The air intake port 6a is separated from the compressor impeller 3 in the central axis direction. The air intake port 6a is connected to an air cleaner (not shown).

[0029] The bearing housing 4 and the compressor housing 6 define a diffuser flow path 60 therebetween. The diffuser flow path 60 has an annular shape surrounding the compressor impeller 3. The diffuser flow path 60 is in fluid communication with the intake port 6a via the compressor impeller 3.

[0030] The compressor housing 6 includes a scroll flow path 61. The scroll flow path 61 is located radially outward of the diffuser flow path 60. The scroll flow path 61 is in fluid communication with the diffuser flow path 60. In addition, the scroll flow path 61 is in fluid communication with an intake port of an engine (not shown). The scroll flow path 61 has a substantially scroll shape.

[0031] In the compressor housing 6 as described above, when the compressor impeller 3 rotates, air is sucked into the compressor housing 6 from the air intake port 6a. The air is accelerated and pressurized by centrifugal force while passing through the compressor impeller 3. The air is further pressurized in the diffuser flow path 60 and the vortex flow path 61. The pressurized air flows out from the outlet not shown in the figure and is guided to the air intake port of the engine. In the supercharger TC, the part including the compressor impeller 3 and the compressor housing 6 functions as a centrifugal compressor C.

[0032] The turbine housing 5 includes an exhaust port (housing outlet) 5a at an end surface on the opposite side of the bearing housing 4 in the central axis direction. The exhaust port 5a is separated from the turbine impeller 2 in the central axis direction. The exhaust port 5a is connected to an exhaust gas purification device (not shown).

[0033] The turbine housing 5 includes a space S for accommodating the turbine wheel 2. Specifically, the turbine housing 5 includes a shroud 5b facing the blades 21 of the turbine wheel 2. The shroud 5b faces radially inward and defines at least a portion of the space S. The space S is in fluid communication with the exhaust port 5a.

[0034] The turbine housing 5 includes a first vortex flow path 51 and a second vortex flow path 52 arranged along the central axis direction. Such a turbine T can also be called a "twin-vortex turbine". The first vortex flow path 51 and the second vortex flow path 52 are located radially outward relative to the turbine impeller 2 and the space S. The second vortex flow path 52 is located at a position closer to the exhaust port 5a relative to the first vortex flow path 51 in the central axis direction. The first vortex flow path 51 and the second vortex flow path 52 have a roughly spiral shape. The first vortex flow path 51 and the second vortex flow path 52 are connected to an inlet (not shown) that is fluidly connected to the exhaust port of the engine. The first vortex flow path 51 and the second vortex flow path 52 receive exhaust gas from the engine. The first vortex flow path 51 and the second vortex flow path 52 are connected to the space S in parallel with each other.

[0035] In the present embodiment, there are no blades for adjusting the flow of exhaust gas between the first vortex flow path 51 and the second vortex flow path 52 and the turbine impeller 2. In other words, the first vortex flow path 51 and the second vortex flow path 52 are directly connected to the space S. Therefore, in the present embodiment, the first vortex flow path 51 and the second vortex flow path 52 are directly opposite to the turbine impeller 2 in the radial direction.

[0036] For example, the first scroll flow path 51 is Figure 1 In the cross section, it extends approximately parallel to the radial direction. Figure 1 In the cross section of FIG. 5 , the second scroll flow path 52 is inclined with respect to the radial direction so as to be away from the exhaust port 5 a in the central axis direction as it approaches the turbine impeller 2 in the radial direction.

[0037] As described above, the exhaust gas from the engine is taken into the first vortex flow path 51 and the second vortex flow path 52. The exhaust gas is guided to the turbine impeller 2 by the first vortex flow path 51 and the second vortex flow path 52, and then guided to the exhaust port 5a. The exhaust gas rotates the turbine impeller 2 while passing through the turbine impeller 2. The rotational force of the turbine impeller 2 is transmitted to the compressor impeller 3 via the shaft 1. When the compressor impeller 3 rotates, as described above, air is sucked in from the intake port 6a, and is accelerated and pressurized by the compressor impeller 3. In the supercharger TC, the portion including the turbine impeller 2 and the turbine housing 5 functions as a turbine T.

[0038] Next, the region including the outlet 54 of the second scroll flow path 52 will be described in detail.

[0039] Figure 2 Yes means Figure 1 The enlarged cross-sectional view of the region A in FIG. 5 shows a region including the outlet 54 of the second scroll flow path 52 . The outlet 54 is a section closest to the space S in the second scroll flow path 52 . Figure 2 and Figure 1 Likewise, a cross section parallel to the central axis of the turbine impeller 2 and including the central axis is shown.

[0040] The second vortex flow path 52 includes a surface 53 connected to the shroud 5b. The surface 53 faces radially outward. Figure 2 In the cross section, the region including the outlet 54 of the second vortex flow path 52 includes the first portion P1 and the second portion P2. In other words, the first portion P1 and the second portion P2 are located between the surface 53 and the shroud 5b, and the surface 53 and the shroud 5b are connected to each other via the first portion P1 and the second portion P2.

[0041] exist Figure 2 In the cross section of , the first portion P1 has a straight line shape parallel to the radial direction. The first portion P1 is located radially outward relative to the shroud 5b. The first portion P1 is formed continuously with the shroud 5b.

[0042] exist Figure 2 In the cross section of , the second portion P2 has an R shape. Therefore, the second portion P2 has a circular shape (arc shape). The second portion P2 is located radially outward relative to the first portion P1. The second portion P2 is formed continuously with the first portion P1.

[0043] For example, the turbine housing 5 including the first part P1 and the second part P2 can be manufactured as follows. First, the turbine housing 5 is formed by casting. For example, the first vortex flow path 51 and the second vortex flow path 52 can be formed using a core. Then, the shroud 5b is finished by machining. During machining, the first part P1 and the second part P2 are not machined. Therefore, the first part P1 and the second part P2 of the turbine housing 5 as a finished product have a casting black skin. For example, when the first part P1 and the second part P2 are machined, the boundary between the second part P2 and the area within the second vortex flow path 52 is difficult to be machined smoothly. Such difficult machining increases manufacturing costs. However, in the present embodiment, the first part P1 and the second part P2 remain as casting black skin, so such machining is not required. In addition, according to such a structure, for example, the first part P1 having a straight shape can be used as a reference for subsequent machining.

[0044] In the turbine T as described above, the direction of the flow of the exhaust gas flowing in the second vortex flow path 52 is reversed in the direction of the central axis when it flows into the space S. In particular, in the present embodiment, the second vortex flow path 52 is directly connected to the space S, so the flow of the exhaust gas turns sharply when it flows into the space S. Therefore, after the direction of the flow is reversed, the flow along the surface 53 is easily peeled off in the area along the shroud 5b. However, in the present embodiment, the area including the outlet 54 includes the second part P2 having an R shape and the first part P1 having a straight shape along the flow of the exhaust gas. Thus, since the direction of the flow along the surface 53 is reversed while passing through the second part P2 and the first part P1, the flow along the surface 53 is easy to follow other flows. As a result, for example, compared with a case where there is no one or both of the R shape and the straight shape, peeling in the area along the shroud 5b can be suppressed.

[0045] Next, the analysis results of the region including the outlet 54 of the second scroll flow path 52 will be described.

[0046] Use with Figure 1 and Figure 2 CFD (Computational Fluid Dynamics) analysis was performed using the same model as the turbine T shown. Also, the same analysis was performed using the model of the comparative example.

[0047] Figure 3 1 is an enlarged cross-sectional view showing a turbine T1 of a first comparative example. The turbine T1 is different from the turbine T of the above-described embodiment in the shape of a region including an outlet 54. The turbine T1 may be the same as the turbine T in other configurations.

[0048] In the turbine T1, the turbine housing 5 does not include the first portion P1 and the second portion P2 described above. The surface 53 and the shroud 5b are directly connected to each other via a sharp corner SC.

[0049] Figure 4 1 is an enlarged cross-sectional view showing a turbine T2 of a second comparative example. The turbine T2 is different from the turbine T of the above-described embodiment in the shape of a region including the outlet 54. The turbine T2 may be the same as the turbine T in other configurations.

[0050] In the turbine T2, the turbine housing 5 includes a third portion P3 instead of the first portion P1 and the second portion P2 described above. The third portion P3 has an R shape. That is, in the turbine T2, only the third portion P3 having an R shape is located between the surface 53 and the shroud 5b. For example, the radius of the R shape of the third portion P3 is greater than the radius of the R shape of the second portion P2 described above.

[0051] Figure 5 It is an enlarged cross-sectional view showing the analysis results of the entropy of the turbines T, T1, and T2 of the embodiment, the first comparative example, and the second comparative example. In the analysis, the same conditions were used except for the shape of the region including the outlet 54. Figure 5 The upper figure in FIG. 1 shows the analysis result of the turbine T1 of the first comparative example. Figure 5 The middle figure in FIG. 1 shows the analysis result of the turbine T2 of the second comparative example. Figure 5 The lower figure in shows the analysis result of the turbine T according to the embodiment.

[0052] like Figure 5 As shown, the region Emax with high entropy (black region) decreases in the order of turbine T1, turbine T2, and turbine T. That is, in the turbine T of the embodiment, the separation in the region along the shroud 5b is the smallest.

[0053] Figure 6 It is a graph showing the analysis results of the turbine efficiency of the turbines T, T1, and T2 according to the embodiment, the first comparative example, and the second comparative example. Figure 6 express Figure 5 The turbine efficiency of each model in the analysis results of For example, the turbine efficiency can be calculated by dividing the heat applied to the turbine by the turbine output.

[0054] like Figure 6 As shown, as the peeling decreases, the turbine efficiency increases in the order of the turbine T1 , the turbine T2 , and the turbine T. In this way, according to the turbine T of the embodiment, the turbine efficiency can be improved.

[0055] The turbine T as described above includes a turbine impeller 2 and a turbine housing 5 that accommodates the turbine impeller 2. The turbine housing 5 includes an exhaust port 5a that is separated from the turbine impeller 2 in the central axis direction and discharges the exhaust gas that has passed through the turbine impeller 2; a first vortex flow path 51 that is located radially outside the turbine impeller 2 and guides the exhaust gas to the turbine impeller 2; and a second vortex flow path 52 that is located radially outside the turbine impeller 2 and is located at a position closer to the exhaust port 5a than the first vortex flow path 51 in the central axis direction and guides the fluid to the turbine impeller 2. The second vortex flow path 52 is inclined relative to the radial direction in a cross section that is parallel to the central axis and includes the central axis so as to be away from the exhaust port 5a in the central axis direction as it approaches the turbine impeller 2 in the radial direction. In addition, in the above-mentioned cross section, the area including the outlet 54 of the second vortex flow path 52 includes: a first portion P1 having a straight line shape parallel to the radial direction; and a second portion P2 having an R shape and continuously formed radially outward relative to the first portion P1. According to such a structure, the direction of the flow along the surface 53 is reversed while passing through the second portion P2 and the first portion P1, so that the flow along the surface 53 is easy to follow other flows. Therefore, for example, compared with the case where there is no R shape and one or both of the straight line shape, it is possible to suppress peeling in the area along the shroud 5b. As a result, the turbine efficiency can be improved.

[0056] In the turbine T, the first portion P1 and the second portion P2 have cast black. According to such a structure, for example, the first portion P1 having a straight shape can be used as a reference for subsequent processing. In addition, difficult machining is not required.

[0057] In the turbine T, the first scroll flow path 51 and the second scroll flow path 52 are directly connected to the space S housing the turbine impeller 2. In such a structure, the exhaust gas flowing in the second scroll flow path 52 turns sharply when flowing into the space S. Therefore, the effect of suppressing separation is more easily exerted.

[0058] Please refer to the attached Figure 1 While the embodiments of the present invention have been described, the present invention is not limited to the embodiments. It is obvious that those skilled in the art can think of various changes or modifications within the scope of the claims, and it should be understood that they also belong to the technical scope of the present invention.

[0059] For example, in the above-described embodiment, the turbine T does not include blades for adjusting the flow of exhaust gas between the first and second scroll flow passages 51 and 52 and the turbine impeller 2. However, in other embodiments, the turbine may include such blades.

[0060] Explanation of symbols

[0061] 2—turbine impeller (impeller), 5—turbine housing (housing), 5a—exhaust port (housing outlet), 51—first vortex flow path, 52—second vortex flow path, 54—outlet of the second vortex flow path, P1—first part, P2—second part, S—space for accommodating the turbine impeller, T—turbine.

Claims

1. A turbine, characterized in that: have: impeller; as well as a casing, which houses the housing of the impeller, The housing comprises: a casing outlet, which is separated from the impeller in the direction of the central axis of the impeller and discharges the fluid that has passed through the impeller; a first vortex flow path located outside the impeller in a radial direction of the impeller and guiding a fluid toward the impeller; and a second vortex flow path, which is located outside the impeller in the radial direction and closer to the housing outlet relative to the first vortex flow path in the central axis direction, and guides the fluid to the impeller; The second vortex flow path is inclined relative to the radial direction in a cross section that is parallel to the center axis of the impeller and includes the center axis in a manner that moves away from the casing outlet in the direction of the center axis as it approaches the impeller in the radial direction. In the cross section, the area including the outlet of the second vortex flow path includes: a first part having a straight line shape parallel to the radial direction; and a second part having an R shape and formed continuously radially outward relative to the first part.

2. The turbine according to claim 1, characterized in that The first portion and the second portion have a cast black skin.

3. The turbine according to claim 1 or 2, characterized in that The first scroll flow path and the second scroll flow path are directly connected to a space accommodating the impeller.

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