Turbine

Abstract

Turbine (T), with: a housing (5) in which a receiving unit (27) for receiving a turbine impeller (15) is formed; a first exhaust gas flow path (29a, 129b) which is formed in the housing (5) and is connected to the receiving unit (27); a second exhaust gas flow path (29b, 129a) formed in the housing (5) and connected to the receiving unit (27) at a position which differs in a circumferential direction of the turbine impeller (15) from a position where the receiving unit (27) and the first exhaust gas flow path (29a, 129b) are connected, wherein the second exhaust gas flow path (29b, 129a) has a flow path cross-sectional area which is smaller than a flow path cross-sectional area of ​​the first exhaust gas flow path (29a, 129b); an exhaust flow path (25) which is formed in the housing (5) and is connected to the receiving unit (27) in an axial direction of the turbine impeller (15); a first bypass flow path (39a, 239b) that connects the first exhaust flow path (29a, 129b) and the discharge flow path (25); a second bypass flow path (39b, 239a) connecting the second exhaust flow path (29b, 129a) and the discharge flow path (25), wherein the second bypass flow path (39b, 239a) has a flow path cross-sectional area larger than a flow path cross-sectional area of ​​the first bypass flow path (39a, 239b), a first tongue (45a, 45b) that separates the first exhaust gas flow path (29a, 129b) and the second exhaust gas flow path (29b, 129a), wherein the first tongue (45a, 45b) is contained at a position in the housing (5) opposite a downstream end of the first exhaust gas flow path (29a, 129b); and a second tongue (45b, 45a) that separates the second exhaust gas flow path (29b, 129a) and the first exhaust gas flow path (29a, 129b), wherein the second tongue (45b, 45a) is contained at a position in the housing (5) opposite a downstream end of the second exhaust gas flow path (29b, 129a), wherein the flow path cross-sectional area of ​​the first exhaust gas flow path (29a, 129b) is a first minimum exhaust gas area Aa, where the flow path cross-sectional area is smallest in a section of the first exhaust gas flow path (29a, 129b) opposite the second tongue (45b), the flow path cross-sectional area of ​​the second exhaust gas flow path (29b, 129a) is a second minimum exhaust gas area Ab, where the flow path cross-sectional area is smallest in a section of the second exhaust gas flow path (29b, 129a) opposite the first tongue (45a), the flow path cross-sectional area of ​​the first bypass flow path (39a, 239b) is a first minimum bypass area Ba, where the flow path cross-sectional area in the first bypass flow path (39a, 239b) is smallest, the flow path cross-sectional area of ​​the second bypass flow path (39b, 239a) is a second minimum bypass area Bb, where the flow path cross-sectional area in the second bypass flow path (39b, 239a) is smallest, and, compared to a difference between a first effective area Aaf, derived from the first minimum exhaust area Aa and a constriction area of ​​the turbine impeller (15), and a second effective area Abf, derived from the second minimum exhaust area Ab and a constriction area of ​​the turbine impeller (15), a difference between a sum of the first effective area Aaf and the first minimum bypass area Ba and a sum of the second effective area Abf and the second minimum bypass area Bb is smaller.

Description

Technical field

[0001] The present invention relates to a turbine. The present application claims priority based on Japanese patent application No. 2019-040384, which was filed on March 6, 2019. State of the art

[0002] Turbochargers comprise a turbine. In a turbine described in JP 2017-180 286 A, two exhaust gas flow paths are formed. The two exhaust gas flow paths are arranged side by side in the radial direction of a turbine impeller. The two exhaust gas flow paths are connected to a receiving unit, which holds the turbine impeller, at different positions in the circumferential direction of the turbine impeller. JP 2010-229 828 A discloses a turbine with two exhaust gas flow paths that have different flow path cross-sectional areas. JP 2018-172 989 A discloses further prior art. Summary: Technical Task

[0003] The two exhaust flow paths are typically provided with two bypass flow paths. These two bypass flow paths have essentially the same flow path cross-sectional area. However, there are cases where the two exhaust flow paths have different flow path cross-sectional areas due to design constraints. In such cases, where the flow path cross-sectional areas of the two exhaust flow paths differ, the engine backpressure fluctuates when the exhaust gas is expelled while the two bypass flow paths are open.

[0004] One object of the present invention is to provide a turbine that is capable of reducing fluctuations in the back pressure of the power engine. Solution to the task

[0005] The above problem is solved by a turbine according to claim 1. The turbine according to the invention comprises: a housing in which a receiving unit for receiving a turbine impeller is formed; a first exhaust gas flow path formed in the housing and connected to the receiving unit; a second exhaust gas flow path formed in the housing and connected to the receiving unit at a position that differs in a circumferential direction of the turbine impeller from a position at which the receiving unit and the first exhaust gas flow path are connected, wherein the second exhaust gas flow path has a flow path cross-sectional area that is smaller than a flow path cross-sectional area of ​​the first exhaust gas flow path; an exhaust flow path formed in the housing and connected to the receiving unit in an axial direction of the turbine impeller;a first bypass flow path connecting the first exhaust flow path and the discharge flow path; and a second bypass flow path connecting the second exhaust flow path and the discharge flow path, wherein the second bypass flow path has a flow path cross-sectional area larger than the flow path cross-sectional area of ​​the first bypass flow path.

[0006] The second exhaust flow path can have a greater length than the first exhaust flow path.

[0007] The first exhaust gas flow path can have a greater length than the second exhaust gas flow path.

[0008] Furthermore, according to the invention, the following are included: a first tongue separating the first exhaust gas flow path and the second exhaust gas flow path, wherein the first tongue is located in the housing opposite a downstream end of the first exhaust gas flow path; and a second tongue separating the second exhaust gas flow path and the first exhaust gas flow path, wherein the second tongue is located in the housing opposite a downstream end of the second exhaust gas flow path, in which the flow path cross-sectional area of ​​the first exhaust gas flow path is a first minimum exhaust gas area, in which the flow path cross-sectional area is smallest in a section of the first exhaust gas flow path opposite the second tongue, and the flow path cross-sectional area of ​​the second exhaust gas flow path is a second minimum exhaust gas area.where the flow path cross-sectional area is smallest in a section of the second exhaust flow path opposite the first tongue, the flow path cross-sectional area of ​​the first bypass flow path is a first minimum bypass area, where the flow path cross-sectional area is smallest in the first bypass flow path, the flow path cross-sectional area of ​​the second bypass flow path is a second minimum bypass area, where the flow path cross-sectional area is smallest in the second bypass flow path, and, compared with a difference between a first effective area derived from the first minimum exhaust area and a constriction area of ​​the turbine impeller, and a second effective area derived from the second minimum exhaust area and a constriction area of ​​the turbine impeller,a difference between the sum of the first effective area and the first minimum bypass area, and between the sum of the second effective area and the second minimum bypass area, can be smaller.

[0009] If the first minimum exhaust area is designated by Aa, the second minimum exhaust area is designated by Ab, a total constriction area of ​​the turbine impeller is designated by Ai, a constriction area of ​​an opposite section of the turbine impeller facing the first exhaust flow path is designated by Aia, a constriction area of ​​an opposite section of the turbine impeller facing the second exhaust flow path is designated by Aib, a central angle of the opposite section of the turbine impeller facing the first exhaust flow path is designated by θa, a central angle of the opposite section of the turbine impeller facing the second exhaust flow path is designated by θb, the first effective area is designated by Aaf, and the second effective area is designated by Abf,The first effective area Aaf can be derived from equation (1) and equation (1a), and the second effective area Abf can be derived from equation (2) and equation (2a). Aaf=Aa⋅AiaAa2+Aia2 Aia=Ai⋅θaθa+θb Abf=Ab⋅AibAb2+Aib2 Aib=Ai⋅θbθa+θb Effects of the invention

[0010] According to the present invention, it is possible to reduce fluctuations in the back pressure of the power machine. Brief description of the drawings Fig. Figure 1 is a schematic sectional view of a turbocharger. Fig. 2 is a sectional view along a line AA of the turbine casing, which is located in Fig. 1 is shown. Fig. Figure 3 is a schematic perspective view of the turbine housing, viewed from one side of a wastegate opening. Fig. Figure 4 is a sectional view along a line AA of a turbine casing in a comparative example. Fig. Figure 5 is a diagram to explain the total constriction area of ​​the turbine impeller. Fig. Figure 6 is a diagram to explain the inner diameter-side constriction area and the outer diameter-side constriction area of ​​the turbine impeller. Fig. Figure 7 is a sectional view along a line AA of a turbine casing of a modification. Description of embodiments

[0011] One embodiment of the present invention is described below with reference to the accompanying drawings. Dimensions, materials, other specific numerical values, and the like shown in the embodiments are merely examples to facilitate understanding, and the present invention is not limited by them unless otherwise described. It should be noted that in this description and the drawings, components having essentially the same function and structure are designated by the same reference numeral, and redundant explanations are omitted. Components not directly related to the present invention are not shown.

[0012] Fig. Figure 1 is a schematic sectional view of a turbocharger TC. The description assumes the direction of an arrow L pointing in Fig. Figure 1 shows the left side of the turbocharger TC. The description assumes a direction of arrow R, which points in Fig. Figure 1 shows the right side of the turbocharger TC. As shown in Fig. As shown in Figure 1, the turbocharger TC comprises a turbocharger main body 1. The turbocharger main body 1 includes a bearing housing 3, a turbine housing 5, and a compressor housing 7. The turbine housing 5 is coupled to the left side of the bearing housing 3 by a fastening mechanism 9. The compressor housing 7 is coupled to the right side of the bearing housing 3 by a fastening bolt 11. A turbine T comprises the bearing housing 3 and the turbine housing 5. A radial compressor C comprises the bearing housing 3 and the compressor housing 7.

[0013] A projection 3a is formed on the outer curved surface of the bearing housing 3. Projection 3a is located closer to the turbine housing 5 and extends radially outward from the bearing housing 3. A projection 5a is also formed on the outer curved surface of the turbine housing 5. Projection 5a is located closer to the bearing housing 3 and extends radially outward from the turbine housing 5. The bearing housing 3 and the turbine housing 5 are fastened together by a band through the fastening mechanism 9. The fastening mechanism 9 includes, for example, a G-coupling. The fastening mechanism 9 clamps projections 3a and 5a.

[0014] A bearing bore 3b is formed in the bearing housing 3. The bearing bore 3 penetrates the turbocharger TC in the left-right direction. The bearing bore 3b pivotally supports a shaft 13 by means of a plain bearing in a freely rotatable manner. A turbine impeller 15 is provided at the left end of the shaft 13. The turbine impeller 15 is arranged in the turbine housing 5. The turbine impeller 15 is mounted in the turbine housing 5 in a freely rotatable manner. A compressor impeller 17 is provided at a right end of the shaft 13. The compressor impeller 13 is arranged in the compressor housing 7. The compressor impeller 17 is mounted in the compressor housing 7 in a freely rotatable manner.

[0015] An inlet opening 19 is formed in the compressor housing 7. The inlet opening 19 opens towards the right side of the turbocharger TC. The inlet opening 19 is connected to an air filter (not shown). Opposing surfaces of the bearing housing 3 and the compressor housing 7 form a diffuser flow path 21. The diffuser flow path 21 pressurizes the air. The diffuser flow path 21 is annular in shape. The diffuser flow path 21 is connected to the inlet opening 19 via the compressor impeller 17 on an inner surface in the radial direction of the shaft 13.

[0016] A compressor spiral flow path 23 is formed in the compressor housing 7. The compressor spiral flow path 23 is annular in shape. The compressor spiral flow path 23 is located on the outer side in the radial direction of the shaft 13 with respect to the diffuser flow path 21. The compressor spiral flow path 23 is connected to an inlet port of a power unit (not shown) and the diffuser flow path 21. When the compressor impeller 17 rotates, air is drawn from the inlet port 19 into the compressor housing 7. The drawn-in air is pressurized and accelerated as it flows between the blades of the compressor impeller 17. The pressurized and accelerated air is further pressurized by the diffuser flow path 21 and the compressor spiral flow path 23. The pressurized air is directed to the inlet opening of the engine.

[0017] The turbine housing 5 incorporates an exhaust flow path 25, a receiving unit 27, and an exhaust gas flow path 29. The exhaust flow path 25 opens to the left side of the turbocharger TC. The exhaust flow path 25 is connected to an exhaust gas purification device (not shown). The exhaust gas flow path 25 is connected to the receiving unit 27. The exhaust gas flow path 25 extends through the receiving unit 27 in the direction of rotation of the turbine impeller 15. The receiving unit 27 accommodates the turbine impeller 15. The exhaust gas flow path 29 is located on an outer surface in the radial direction of the receiving unit 27 (of the turbine impeller 15). The exhaust gas flow path 29 is connected to the receiving unit 27. The exhaust gas flow path 29 extends through the receiving unit 27 in the radial direction of the turbine impeller 15.

[0018] Fig. Figure 2 is a sectional view along a line AA of the turbine casing 5, which is located in Fig. 1 is shown. Fig. Figure 2 shows only the outer circumference of the turbine impeller 15 as a circle. As in Fig. As shown in Figure 2, the exhaust gas flow path 29 is formed on the outside in the radial direction of the receiving unit 27 (of the turbine impeller 15). The exhaust gas flow path 29 comprises a connecting unit 31, a turbine spiral flow path 33, an exhaust gas inlet opening 35, and an exhaust gas inlet path 37.

[0019] The connecting unit 31 is formed in an annular shape over the entire circumference of the receiving unit 27. The turbine spiral flow path 33 is arranged, for example, on an outer surface in the radial direction of the turbine impeller 15 with respect to the connecting unit 31. The turbine spiral flow path 33 is formed in an annular shape over the entire circumference of the connecting unit 31 (receiving unit 27). The connecting unit 31 connects the receiving unit 27 to the turbine spiral flow path 33.

[0020] The exhaust gas inlet opening 35 opens to the outside of the turbine housing 5. Exhaust gas expelled from an exhaust manifold of the engine (not shown) is admitted into the exhaust gas inlet opening 35. The exhaust gas inlet path 37 is formed between the exhaust gas inlet opening 35 and the turbine spiral flow path 33. The exhaust gas inlet path 37 connects the exhaust gas inlet opening 35 and the turbine spiral flow path 33. The exhaust gas inlet path 37 is, for example, configured as a straight line. The exhaust gas inlet path 37 directs the exhaust gas admitted from the exhaust gas inlet opening 35 to the turbine spiral flow path 33. The turbine spiral flow path 33 directs the exhaust gas admitted from the exhaust gas inlet path 37 to the receiving unit 27 via the connecting unit 31. As described above, the exhaust gas flow path 29 comprises the exhaust gas inlet opening 35, the exhaust gas inlet path 37, the turbine spiral flow path 33, and the connecting unit 31.The exhaust gas flow path 29 extends from the exhaust gas inlet opening 35 to the connecting unit 31.

[0021] A bypass flow path 39 is formed in the turbine housing 5. In the bypass flow path 39, an inlet OP opens into the exhaust flow path 29, and an outlet (wastegate opening WP, described below) opens into the exhaust flow path 25 (see Fig. 1) More precisely, in the bypass flow path 39, the inlet end OP opens into the exhaust inlet path 37, and the outlet end opens into the exhaust flow path 25. The bypass flow path 39 connects (brings together) the exhaust inlet path 37 and the exhaust flow path 25.

[0022] The wastegate opening WP (see Fig. 1) is formed at the outlet end of the bypass flow path 39. A wastegate valve WV (see Fig. 1), which is capable of opening and closing the wastegate opening WP, is located at the outlet end of the bypass flow path 39. The wastegate valve WV is located in the exhaust flow path 25. When the wastegate valve WV opens the wastegate opening WP, the bypass flow path 39 allows a portion of the exhaust gas flowing through the exhaust inlet path 37 to bypass the receiving unit 27 (the turbine impeller 15) and flow out into the exhaust flow path 25.

[0023] A partition plate 41 is formed in the turbine housing 5. The partition plate 41 is arranged in the exhaust gas flow path 29. More precisely, the partition plate 41 is arranged in the exhaust gas inlet opening 35, the exhaust gas inlet path 37, and the turbine spiral flow path 33. The partition plate 41 is connected to the inner surfaces of the exhaust gas inlet opening 35, the exhaust gas inlet path 37, and the turbine spiral flow path 33 in the direction of rotation of the turbine impeller 15 (hereinafter also referred to as the transverse direction of the partition plate 41). The partition plate 41 extends in a direction away from the exhaust gas inlet opening 35. The partition plate 41 extends along the exhaust gas flow path 29. That is, the partition plate 41 extends along the direction of exhaust gas flow (hereinafter also referred to as the longitudinal direction of the partition plate 41).Hereinafter, the upstream side in the exhaust gas flow direction is simply referred to as the upstream side, and the downstream side in the exhaust gas flow direction is simply referred to as the downstream side. The upstream end of the partition plate 41 is located at the exhaust gas inlet opening 35, and the downstream end is located at a position (boundary) between the turbine spiral flow path 33 and the connecting unit 31.

[0024] The partition plate 41 separates (divides) the exhaust gas flow path 29 in the radial direction (hereinafter simply referred to as the radial direction) of the turbine impeller 15. The exhaust gas flow path 29 is divided by the partition plate 41 into an inner-diameter-side exhaust gas flow path (first exhaust gas flow path) 29a and an outer-diameter-side exhaust gas flow path (second exhaust gas flow path) 29b. The inner-diameter-side exhaust gas flow path 29 is located on an inner surface in the radial direction of the turbine impeller 15 with respect to the outer-diameter-side exhaust gas flow path 29b. The inner-diameter-side exhaust gas flow path 29 is formed side by side with the outer-diameter-side exhaust gas flow path 29b in the radial direction. The outer-diameter-side exhaust gas flow path 29b has a greater length than that of the inner-diameter-side exhaust gas flow path 29a.

[0025] The partition plate 41 divides the exhaust gas inlet opening 35 radially. The exhaust gas inlet opening 35 is divided by the partition plate 41 into an inner-diameter exhaust gas inlet opening 35a and an outer-diameter exhaust gas inlet opening 35b. The inner-diameter exhaust gas inlet opening 35a is located on the inside of the turbine impeller 15 in the radial direction relative to the outer-diameter exhaust gas inlet opening 35b. The inner-diameter exhaust gas inlet opening 35a is formed side by side with the outer-diameter exhaust gas inlet opening 35b in the radial direction.

[0026] The exhaust manifold (not shown) comprises two (or a plurality of) split paths. Each of the two split paths is connected to one of the inner-diameter exhaust inlet ports 35a and the other to the outer-diameter exhaust inlet port 35b. Exhaust gas expelled from a power engine (not shown) flows through the two split paths of the exhaust manifold and is admitted to the inner-diameter exhaust inlet port 35a and the outer-diameter exhaust inlet port 35b. Of the exhaust gas flowing through the two split paths, a portion is admitted to the inner-diameter exhaust inlet port 35a, and the other portion is admitted to the outer-diameter exhaust inlet port 35b.

[0027] The partition plate 41 divides the exhaust gas inlet path 37 in the radial direction. The exhaust gas inlet path 37 is divided by the partition plate 41 into an inner-diameter-side exhaust gas inlet path 37a and an outer-diameter-side exhaust gas inlet path 37b. The inner-diameter-side exhaust gas inlet path 37a is located on the inside of the turbine impeller 15 in the radial direction relative to the outer-diameter-side exhaust gas inlet path 37b. The inner-diameter-side exhaust gas inlet path 37a is formed side by side with the outer-diameter-side exhaust gas inlet path 37b in the radial direction of the turbine impeller 15. The inner-diameter-side exhaust gas inlet path 37a is connected to the inner-diameter-side exhaust gas inlet opening 35a. The outer-diameter-side exhaust gas inlet path 37b is connected to the outer-diameter-side exhaust gas inlet opening 35b.

[0028] Fig. Figure 3 is a schematic perspective view of the turbine housing 5, viewed from one side of the wastegate opening WP. Fig. Figure 3 does not show the wastegate valve (WV). As in Fig. As shown in Figure 3, a partition 43 is formed in the bypass flow path 39. One end of the partition 43 is at the inlet end OP (see Figure 3). Fig. 2) of the bypass flow path 39, and the other end is arranged at the outlet end (wastegate opening WP) of the bypass flow path 39.

[0029] The partition 43 extends along the exhaust gas flow direction (hereinafter also referred to as the longitudinal direction of the partition 43) in which the exhaust gas flows through the bypass flow path 39. The partition 43 is connected to the inner surface of the bypass flow path 39 in a transverse direction D that is perpendicular to the longitudinal direction of the partition 43. The partition 43 divides the bypass flow path 39. The bypass flow path 39 is divided by the partition 43 into an inner-diameter-side bypass flow path (first bypass flow path) 39a and an outer-diameter-side bypass flow path (second bypass flow path) 39b.

[0030] Referring again to Fig. 2, the inner diameter-side bypass flow path 39a is connected to the inner diameter-side exhaust gas inlet path 37a. The inner diameter-side bypass flow path 39a connects the inner diameter-side exhaust gas inlet path 37a and the exhaust flow path 35 (see Fig. 1 and Fig. 3) The inner diameter-side bypass flow path 39a directs a portion of the exhaust gas flowing through the inner diameter-side exhaust gas inlet path 37a to the wastegate opening WP (see Fig. 1 and Fig. 3) The outer diameter-side bypass flow path 39b is connected to the outer diameter-side exhaust gas inlet path 37b. The outer diameter-side bypass flow path 39b connects the outer diameter-side exhaust gas inlet path 37b and the exhaust flow path 25. The outer diameter-side bypass flow path 39b directs a portion of the exhaust gas flowing through the outer diameter-side bypass flow path 39b to the wastegate opening WP.

[0031] The partition plate 41 divides the turbine spiral flow path 33 in the radial direction. The turbine spiral flow path 33 is divided by the partition plate 41 into an inner-diameter-side turbine spiral flow path 33a and an outer-diameter-side turbine spiral flow path 33b. The inner-diameter-side turbine spiral flow path 33a is arranged radially on the inside with respect to the outer-diameter-side turbine spiral flow path 33b. The inner-diameter-side turbine spiral flow path 33a is formed side by side with the outer-diameter-side turbine spiral flow path 33b in the radial direction. The inner-diameter-side turbine spiral flow path 33a is connected to the inner-diameter-side exhaust gas inlet path 37a. The outer-diameter-side turbine spiral flow path 33b is connected to the outer-diameter-side exhaust gas inlet path 37b.

[0032] The radial width of the inner-diameter-side turbine spiral flow path 33a decreases as it extends away from the inner-diameter-side exhaust gas inlet path 37a. That is, the radial width of the inner-diameter-side turbine spiral flow path 33a decreases as it extends from the upstream side to the downstream side.

[0033] The radial width of the outer-diameter-side turbine spiral flow path 33b decreases as it extends away from the outer-diameter-side exhaust gas inlet path 37b. That is, the radial width of the outer-diameter-side turbine spiral flow path 33b decreases as it extends from the upstream side to the downstream side.

[0034] The connecting unit 31 is connected to the inner diameter-side turbine spiral flow path 33a on the left half-circumference in Fig. 2 in connection. Hereinafter, the section of the connecting unit 31 that is connected to the inner diameter-side turbine spiral flow path 33a is referred to as a first connecting unit 31a. The connecting unit 31a is connected to the outer diameter-side turbine spiral flow path 33b at the right half-circumference in Fig. 2 in connection. Hereinafter, the section of the connecting unit 31 which is connected to the outer diameter-side turbine spiral flow path 33b is referred to as a second connecting unit 31b.

[0035] The receiving unit 27 is connected to the first connecting unit 31a on the left half-circumference in Fig. 2 in connection. The first connecting unit 31a is arranged between the inner diameter-side turbine spiral flow path 33a and the receiving unit 27. The receiving unit 27 is connected to the second connecting unit 31b at the right half-circumference in Fig. 2 in connection. The second connection unit 31b is arranged between the outer diameter-side turbine spiral flow path 33b and the receiving unit 27.

[0036] In this way, the receiving unit 27 is connected to the inner diameter-side exhaust gas flow path 29a on the left half-circumference in Fig. 2 in connection. The receiving unit 27 is connected to the outer diameter-side exhaust gas flow path 29b on the right half-circumference in Fig. 2 in connection. The position of the receiving unit 27, which is connected to the inner diameter-side exhaust gas flow path 29a, differs from its position, which is connected to the outer diameter-side exhaust gas flow path 29b, in the circumferential direction of the turbine impeller 15. In other words, the position at which the receiving unit 27 is connected to the inner diameter-side turbine spiral flow path 33a via the first connecting unit 31a differs from the position at which the receiving unit 27 is connected to the outer diameter-side turbine spiral flow path 33b via the second connecting unit 31b, in the circumferential direction of the turbine impeller 15.

[0037] A first tongue 45a and a second tongue 45b are formed in the turbine housing 5. The first tongue 45a is formed at the downstream end of the partition plate 41 (i.e., the end on the side separated from the exhaust inlet opening 35). The first tongue 45a is located opposite the downstream end of the inner-diameter-side turbine spiral flow path 33a. The first tongue 45a separates the inner-diameter-side turbine spiral flow path 33a from the outer-diameter-side turbine spiral flow path 33b.

[0038] The second tongue 45b is located opposite the downstream end of the outer-diameter-side turbine spiral flow path 33b. The second tongue 45b separates the outer-diameter-side turbine spiral flow path 33b from the inner-diameter-side turbine spiral flow path 33a.

[0039] The phase of the first tongue 45a is approximately 180 degrees offset from that of the second tongue 45b in the direction of rotation of the turbine runner 15. This means that the first tongue 45a and the second tongue 45b are equidistant in the direction of rotation of the turbine runner 15. It is important to note that it is only necessary for the phase (position) of the first tongue 45a to be offset from that of the second tongue 45b in the direction of rotation of the turbine runner 15. The phase offset of the first tongue 45a relative to the second tongue 45b does not have to be approximately 180 degrees. That is, the first tongue 45a and the second tongue 45b can be equidistant in the direction of rotation of the turbine runner 15. The first tongue 45a and the second tongue 45b are radially opposite the turbine runner 15.

[0040] Back to Fig. 1. The exhaust gas expelled from the exhaust manifold of the engine (not shown) is directed to the exhaust flow path 25 via the exhaust flow path 29 and the receiving unit 27. The exhaust gas directed to the exhaust flow path 25 rotates the turbine impeller 15 as it flows through it.

[0041] The rotational force of the turbine impeller 15 is transmitted to the compressor impeller 17 via the shaft 13. When the compressor impeller 17 rotates, the air is pressurized as described above. In this way, the air is directed to the inlet opening of the engine.

[0042] Meanwhile, there are cases in which the inner diameter-side exhaust gas flow path 29a and the outer diameter-side exhaust gas flow path 29b may have different flow path cross-sectional areas due to design constraints. In the present embodiment, as shown in Fig. Figure 2 shows the cross-sectional areas of the flow paths of the inner diameter-side exhaust gas flow path 29a and the outer diameter-side exhaust gas flow path 29b, compared at positions where the distances from the corresponding ends (tongues) of the inner diameter-side turbine spiral flow path 33a and the outer diameter-side turbine spiral flow path 33b are the same. The cross-sectional area of ​​the flow path of the inner diameter-side exhaust gas flow path 29a is larger than the cross-sectional area of ​​the flow path of the outer diameter-side exhaust gas flow path 29b, compared at positions where the distances from the corresponding ends (tongues) of the inner diameter-side turbine spiral flow path 33a and the outer diameter-side turbine spiral flow path 33b are the same.For example, the smallest flow path cross-sectional area in the section of the inner-diameter-side exhaust flow path (first exhaust flow path) 29a opposite the second tongue 45b is defined as a first minimum exhaust area Aa. The smallest flow path cross-sectional area of ​​the outer-diameter-side exhaust flow path (second exhaust flow path) 29b in the section opposite the first tongue 45a is defined as a second minimum exhaust area Ab. In this case, the first minimum exhaust area Aa is larger than the second minimum exhaust area Ab. In other words, the second minimum exhaust area Ab is smaller than the first minimum exhaust area Aa.

[0043] It should be noted that the present embodiment describes an example in which the first minimum exhaust area Aa has a size different from that of the second minimum exhaust area Ab; however, the present invention is not limited to this. For example, the position of a cross-section at which the flow path cross-sectional area is smallest (first minimum exhaust area Aa) in the section of the inner diameter-side exhaust flow path 29a opposite the second tongue 45b is defined as a first cross-sectional position. The position of the cross-section at which the flow path cross-sectional area is smallest (second minimum exhaust area Ab) in the section of the outer diameter-side exhaust flow path 29b opposite the first tongue 45a is defined as a second cross-sectional position.In this case, at cross-sectional positions that are offset by a predetermined distance from the first cross-sectional position and the second cross-sectional position, which are references, closer to the connecting unit 31 (or closer to the exhaust gas inlet opening 35), the flow path cross-sectional areas of the inner diameter-side exhaust gas flow path 29a and the outer diameter-side exhaust gas flow path 29b can be different from each other.

[0044] Fig. Figure 4 is a cross-section along line AA of a turbine casing 105 in a comparative example. As in Fig. As shown in Figure 4, the turbine housing 105 includes a bypass flow path 139. The turbine housing 105 in the comparative example has the same structure as the turbine housing 5 of the present embodiment, except for the bypass flow path 139. The bypass flow path 139 comprises an inner-diameter-side bypass flow path 139a and an outer-diameter-side bypass flow path 139b. The cross-sectional areas of the inner-diameter-side bypass flow path 139a and the outer-diameter-side bypass flow path 139b are essentially the same. The turbine housing 105 has a first minimum exhaust area Aa and a second minimum exhaust area Ab, which are different from each other.

[0045] If the wastegate valve WV is present (see Fig. 1) When the bypass is closed, exhaust gas flows through exhaust gas flow path 29 without flowing through bypass flow path 139. At this point, the exhaust gas flows through exhaust gas flow path 29 at a flow rate that corresponds to the flow path cross-sectional area of ​​the inner diameter-side exhaust gas flow path 29a and the outer diameter-side exhaust gas flow path 29b. Therefore, there is a flow rate difference between the flow rate of the exhaust gas flowing through the inner diameter-side exhaust gas flow path 29a (hereinafter also referred to simply as the inner diameter-side flow rate) and the flow rate of the exhaust gas flowing through the outer diameter-side exhaust gas flow path 29b (hereinafter simply referred to as the outer diameter-side flow rate).

[0046] On the other hand, if the wastegate valve WV (see Fig. 1) If the opening is open, the exhaust gas flows through the exhaust gas flow path 29 and the bypass flow path 139. In this case, the exhaust gas flows through the exhaust gas flow path 29 and the bypass flow path 139 with flow rates corresponding to the cross-sectional areas of the inner diameter-side exhaust gas flow path 29a, the outer diameter-side exhaust gas flow path 29b, the inner diameter-side bypass flow path 139a, and the outer diameter-side bypass flow path 139b. In this case, the cross-sectional areas of the inner diameter-side bypass flow path 139a and the outer diameter-side bypass flow path 139b are essentially the same.

[0047] Therefore, there is a flow rate difference between the flow rate of the exhaust gas flowing through the inner diameter-side exhaust gas flow path 29a and the inner diameter-side bypass flow path 139a (hereinafter simply referred to as the inner diameter-side flow rate), and the flow rate of the exhaust gas flowing through the outer diameter-side exhaust gas flow path 29b and the outer diameter-side bypass flow path 139b (hereinafter simply referred to as the outer diameter-side flow rate). The flow rate difference between the inner diameter-side flow rate and the outer diameter-side flow rate when the wastegate valve WV (see Fig. 1) The flow rate difference between the inner diameter-side flow rate and the outer diameter-side flow rate when the wastegate valve WV is closed is approximately the same as the flow rate difference between the inner diameter-side flow rate and the outer diameter-side flow rate when the wastegate valve WV is open. That is, in the turbine housing 105 of the comparison example, it is difficult to reduce the flow rate difference between the inner diameter-side flow rate and the outer diameter-side flow rate when the wastegate valve WV is open. Therefore, in the turbine housing 105 of the comparison example, the engine back pressure can fluctuate when the wastegate valve WV is open, which can adversely reduce the turbocharging performance of the turbocharger TC.

[0048] Therefore, as in Fig. As shown in Figure 2, in the turbine housing 5 of the present embodiment, the flow path cross-sectional areas of the inner diameter-side bypass flow path 39a and the outer diameter-side bypass flow path 39b differ from each other. More precisely, the flow path cross-sectional areas of the inner diameter-side bypass flow path 39a and the outer diameter-side bypass flow path 39b are different from each other compared to positions where the distances of the inner diameter-side bypass flow path 39a and the outer diameter-side bypass flow path 39b from the wastegate opening WP are the same.In the present embodiment, the cross-sectional area of ​​the flow path of the inner-diameter bypass flow path 39a is smaller than the cross-sectional area of ​​the flow path of the outer-diameter bypass flow path 39b, compared at the positions where the distances of the inner-diameter bypass flow path 39a and the outer-diameter bypass flow path 39b from the wastegate opening WP are equal. In other words, the cross-sectional area of ​​the flow path of the outer-diameter bypass flow path 39b is larger than the cross-sectional area of ​​the flow path of the inner-diameter bypass flow path 39a. More precisely, the opening area of ​​the inlet OP of the inner-diameter bypass flow path 39a is smaller than the opening area of ​​the inlet OP of the outer-diameter bypass flow path 39b.

[0049] As in Fig. As shown in Figure 3, an inner-diameter-side minimum bypass area (first minimum bypass area) Ba, which is the smallest flow path cross-sectional area of ​​the inner-diameter-side bypass flow path 39a, is smaller than an outer-diameter-side minimum bypass area (second minimum bypass area) Bb, which is the smallest flow path cross-sectional area of ​​the outer-diameter-side bypass flow path 39b. For example, the inner-diameter-side minimum bypass area Ba is the opening area of ​​the wastegate opening WP of the inner-diameter-side bypass flow path 39a. The outer-diameter-side minimum bypass area Bb is, for example, the opening area of ​​the wastegate opening WP of the outer-diameter-side bypass flow path 39b.This means that the opening area of ​​the wastegate opening WP of the inner diameter-side bypass flow path 39a is smaller than the opening area of ​​the wastegate opening WP of the outer diameter-side bypass flow path 39b.

[0050] As in Fig. As shown in Figure 2, the cross-sectional areas of the inner diameter-side exhaust gas flow path 29a and the outer diameter-side exhaust gas flow path 29b are different. In the present embodiment, the cross-sectional area of ​​the inner diameter-side exhaust gas flow path 29a (first minimum exhaust gas area Aa) is larger than the cross-sectional area of ​​the outer diameter-side exhaust gas flow path 29b (second minimum exhaust gas area Ab). In other words, the cross-sectional area of ​​the outer diameter-side exhaust gas flow path 29b (second minimum exhaust gas area Ab) is smaller than the cross-sectional area of ​​the inner diameter-side exhaust gas flow path 29a (first minimum exhaust gas area Aa).As a result, the turbine spiral flow path 33, and thus the turbine housing 5, can be reduced in size compared to the case where the flow path cross-sectional area of ​​the outer diameter-side exhaust flow path 29b (second minimum exhaust area Ab) is equal to the flow path cross-sectional area of ​​the inner diameter-side exhaust flow path 29a (first minimum exhaust area Aa). Consequently, the cost of the turbine housing 5 (turbocharger TC) can be reduced.

[0051] As described above, in the turbine housing 5 of the present embodiment, the cross-sectional area of ​​the flow path of the inner diameter-side bypass flow path 39a (inner diameter-side minimum bypass area Ba) is smaller than the cross-sectional area of ​​the flow path of the outer diameter-side bypass flow path 39b (outer diameter-side minimum bypass area Bb). In the turbine housing 5, the inner diameter-side exhaust gas flow path 29a (first minimum exhaust gas area Aa) is larger than the outer diameter-side exhaust gas flow path 29b (second minimum exhaust gas area Ab). That is, the inner diameter-side bypass flow path 39a, whose cross-sectional area is smaller than that of the outer diameter-side bypass flow path 39b, is connected to the inner diameter-side exhaust gas flow path 29a, whose cross-sectional area is larger than that of the outer diameter-side exhaust gas flow path 29b.

[0052] If the wastegate valve WV is present (see Fig. 1) When the wastegate valve WV is closed, exhaust gas flows through the exhaust gas flow path 29 without flowing through the bypass flow path 39. At this point, the exhaust gas flows through the exhaust gas flow path 29 at a flow rate that corresponds to the cross-sectional area of ​​the inner diameter-side exhaust gas flow path 29a and the outer diameter-side exhaust gas flow path 29b. Therefore, a flow rate difference occurs between the inner diameter-side flow rate and the outer diameter-side flow rate when the wastegate valve WV is closed.

[0053] If, on the other hand, the wastegate valve WV (see Fig. 1) If the system is open, the exhaust gas flows through the exhaust gas flow path 29 and the bypass flow path 39. In this case, the exhaust gas flows through the exhaust gas flow path 29 and the bypass flow path 39 at flow rates corresponding to the cross-sectional areas of the inner-diameter-side exhaust gas flow path 29a, the outer-diameter-side exhaust gas flow path 29b, the inner-diameter-side bypass flow path 39a, and the outer-diameter-side bypass flow path 39b. Here, the inner-diameter-side bypass flow path 39a, whose cross-sectional area is smaller than that of the outer-diameter-side bypass flow path 39b, is connected to the inner-diameter-side exhaust gas flow path 29a, whose cross-sectional area is larger than that of the outer-diameter-side exhaust gas flow path 29b.

[0054] Therefore, the flow rate difference between the inner diameter-side flow rate and the outer diameter-side flow rate when the wastegate valve WV is open is smaller than the flow rate difference between the inner diameter-side flow rate and the outer diameter-side flow rate when the wastegate valve WV is closed. Therefore, the turbine housing 5 of the present embodiment can reduce fluctuations in the engine backpressure when the wastegate valve WV is open and can suppress a deterioration in the turbocharging performance of the turbocharger TC.

[0055] The flow rate of the exhaust gas flowing through the inner diameter-side exhaust gas flow path 29a is shown here when the wastegate valve WV (see Fig. 1) is closed, is referred to as an inside-diameter-side flow rate of a closed valve. The flow rate of the exhaust gas flowing through the inside-diameter-side exhaust gas flow path 29a and the inside-diameter-side bypass flow path 39a when the wastegate valve WV is open is referred to as an inside-diameter-side flow rate of an open valve.

[0056] Similarly, the flow rate of the exhaust gas flowing through the outer diameter-side exhaust gas flow path 29b is affected when the wastegate valve WV (see Fig. 1) is closed, referred to as an outside diameter-side flow rate of a closed valve.

[0057] The flow rate of the exhaust gas flowing through the outside diameter-side exhaust gas flow path 29b and the outside diameter-side bypass flow path 39b when the wastegate valve WV is closed is referred to as an outside diameter-side flow rate of an open valve.

[0058] A flow rate difference between the inner diameter flow rate of an open valve and the outer diameter flow rate of an open valve is referred to as the flow rate difference of an open valve. A flow rate difference between the inner diameter flow rate of a closed valve and the flow rate of an open valve is referred to as the flow rate difference of a closed valve.

[0059] According to the preceding embodiment, in the turbine housing 5, the cross-sectional area of ​​the inner diameter-side exhaust gas flow path 29a is comparatively large compared to the cross-sectional area of ​​the outer diameter-side exhaust gas flow path 29b. In the turbine housing 5, the cross-sectional area of ​​the inner diameter-side bypass flow path 39a is comparatively small compared to the cross-sectional area of ​​the bypass flow path 39b. Therefore, it is possible to make the flow rate difference of an open valve smaller than the flow rate difference of a closed valve. Consequently, the turbine housing 5 of the present embodiment can reduce fluctuations in the engine backpressure when the wastegate valve WV is open and suppress a deterioration in the turbocharging performance of the turbocharger TC.

[0060] In the above description, the relationship between the first minimum exhaust gas area Aa and the second minimum exhaust gas area Ab, as well as the inner diameter-side minimum bypass area Ba and the outer diameter-side minimum bypass area Bb, was described.

[0061] The relationship between the effective area when the exhaust gas passes through the turbine impeller 15 via the inner diameter-side exhaust gas flow path 29a and the outer diameter-side exhaust gas flow path 29b, and the inner diameter-side minimum bypass area Ba and the outer diameter-side minimum bypass area Bb is described in detail below.

[0062] The effective area when the exhaust gas passes through the turbine impeller 15 via the inner diameter-side exhaust gas flow path 29a is defined as an inner diameter-side effective area Aaf. The effective area when the exhaust gas passes through the turbine impeller 15 via the outer diameter-side exhaust gas flow path 29b is defined as an outer diameter-side effective area Abf. The details of the inner diameter-side effective area Aaf and the outer diameter-side effective area Abf are described below.

[0063] Aa is the cross-sectional area of ​​the flow path of the inner diameter-side exhaust gas flow path 29a (in the present embodiment, the first minimum exhaust gas area Aa). Ab is the cross-sectional area of ​​the flow path of the outer diameter-side exhaust gas flow path 29b (in the present embodiment, the second minimum exhaust gas area Ab). Ba is the cross-sectional area of ​​the flow path of the inner diameter-side bypass flow path 39a (in the present embodiment, the inner diameter-side minimum bypass area Ba). Bb is the cross-sectional area of ​​the flow path of the outer diameter-side bypass flow path 39b (in the present embodiment, the outer diameter-side minimum bypass area Bb).

[0064] Ai is the total constriction area of ​​the turbine impeller 15. Aia is the constriction area of ​​an opposing section of the turbine impeller 15, which faces the inner diameter-side exhaust gas flow path 29a (hereinafter referred to as the inner diameter-side constriction area). Aib is the constriction area of ​​an opposing section of the turbine impeller 15, which faces the outer diameter-side exhaust gas flow path 29b (hereinafter referred to as the outer diameter-side constriction area). Details of the total constriction area Ai, the inner diameter-side constriction area Aia, and the outer diameter-side constriction area Aib are described below.

[0065] θa is the central angle of the opposite section of the turbine impeller 15, which faces the inner diameter-side exhaust gas flow path 29a (the inner diameter-side constriction area Aia). θb is the central angle of the opposite section of the turbine impeller 15, which faces the outer diameter-side exhaust gas flow path 29b (the outer diameter-side constriction area Aib). Details of the central angles θa and θb are described below.

[0066] In this case, the effective area Aaf on the inner diameter side is derived by the following equation (1). Aaf=Aa⋅AiaAa2+Aia2

[0067] In equation (1) the constriction area Aia on the inner diameter side is derived by the following equation (1a). Aia=Ai⋅θaθa+θb

[0068] In equation (1a) the total constriction area Ai of the turbine impeller 15 is derived approximately by the following equation (1b). Ai=π4(D4s2−D4h2)cos{tan β4s12(D4s2+D4h2)D4s}

[0069] Fig. Figure 5 is a diagram to illustrate the total constriction area Ai of the turbine impeller 15. As in Fig. As shown in Figure 5, the turbine impeller 15 has a hub 15a and blades 15b. The hub 15a is attached to the shaft 13 (see Figure 5). Fig. 1) provided. The hub 15a has a shape in which the diameter decreases when it moves towards the left side. Fig. 5 extends, and enlarges when it moves towards the right side in Fig. 5 extends. The blades 15b are provided on the outer curved surface of the hub 15a. A plurality of blades 15b are provided, spaced apart from each other in the circumferential direction of the hub 15a. The outlet shell diameter of the turbine runner 15 is designated by “D4s”, and the outlet hub diameter of the turbine runner 15 is designated by “D4h”. Additionally, the blade angle on the outlet shell side of the turbine runner 15 is designated by “β4s”. Herein, a total constriction area Ai of the turbine runner 15 is derived by the preceding equation (1b).

[0070] Fig. Figure 6 is a diagram to illustrate the inner diameter-side constriction area Aia and the outer diameter-side constriction area Aib of the turbine impeller 15. As in Fig. As shown in Figure 6, the turbine impeller 15 comprises an opposing section FS1, which faces the inner diameter-side exhaust gas flow path 29a. The inner diameter-side constriction area Aia is the constriction area of ​​the opposing section FS1 of the turbine impeller 15. The central angle θa is the central angle of the opposing section FS1 (the inner diameter-side constriction area Aia) of the turbine impeller 15. It should be noted that the central angle θa is approximately equal to the phase shift between the first tongue 45a and the second tongue 45b on the side of the inner diameter-side exhaust gas flow path 29a.

[0071] The turbine impeller 15 comprises an opposing section FS2, which faces the outer diameter-side exhaust gas flow path 29b. The outer diameter-side constriction area Aib is the constriction area of ​​the opposing section FS2 of the turbine impeller 15. The central angle θb is the central angle of the opposing section FS2 (the outer diameter-side constriction area Aib) of the turbine impeller 15. It should be noted that the central angle θb is approximately equal to the phase shift between the first tongue 45a and the second tongue 45b on the side of the outer diameter-side exhaust gas flow path 29b. In this embodiment, the central angle θa is approximately equal to the central angle θb.

[0072] The effective area Abf on the outer diameter side is derived by the following equation (2). Abf=Ab⋅AibAb2+Aib2

[0073] In equation (2) the outer diameter-side constriction area Aib is derived by the following equation (2a). Aib=Ai⋅θbθa+θb

[0074] As shown in equation (1) above, the inner diameter-side effective area (first effective area) Aaf is derived from the flow path cross-sectional area of ​​the inner diameter-side exhaust gas flow path 29a (first minimum exhaust gas area Aa) and the constriction area of ​​the turbine impeller 15 (inner diameter-side constriction area Aia). As shown in equation (2) above, the outer diameter-side effective area (second effective area) Abf is derived from the flow path cross-sectional area of ​​the outer diameter-side exhaust gas flow path 29b (second minimum exhaust gas area Ab) and the constriction area of ​​the turbine impeller 15 (outer diameter-side constriction area Aib).

[0075] In the present embodiment, the difference between the effective area Aaf on the inner diameter side and the effective area Abf on the outer diameter side is greater than the difference between the sum of the effective area Aaf on the inner diameter side and the minimum circumferential area Ba on the inner diameter side, and the difference between the effective area Abf on the outer diameter side and the minimum circumferential area Bb on the outer diameter side. That is, the difference between the sum of the effective area Aaf on the inner diameter side and the minimum circumferential area Ba on the inner diameter side, and the sum of the effective area Abf on the outer diameter side and the minimum circumferential area Bb on the outer diameter side, is smaller compared to the difference between the effective area Aaf on the inner diameter side and the effective area Abf on the outer diameter side.The difference between the effective area Aaf on the inner diameter side and the effective area Abf on the outer diameter side satisfies the condition of the following equation 3. |(Aaf+Ba)−(Abf+Bb)|<|Aaf−Abf|

[0076] In the present case, the flow rate of the exhaust gas flowing through the inner diameter-side exhaust gas flow path 29a (inner diameter-side flow rate of a closed valve) is derived from the inner diameter-side effective area Aaf when the wastegate valve WV (see Fig. 1) is closed. The flow rate of the exhaust gas flowing through the inner diameter-side exhaust gas flow path 29a and the inner diameter-side bypass flow path 39a (inner diameter-side flow rate of an open valve) is derived from the inner diameter-side effective area Aaf and the inner diameter-side minimum bypass area Ba when the wastegate valve WV is open.

[0077] Similarly, the flow rate of the exhaust gas flowing through the outer diameter-side exhaust gas flow path 29b (outer diameter-side flow rate of a closed valve) is derived from the outer diameter-side effective area Abf when the wastegate valve WV (see Fig. 1) is closed. The flow rate of the exhaust gas flowing through the outside diameter-side exhaust gas flow path 29b and the outside diameter-side bypass flow path 39b (outside diameter-side flow rate of an open valve) is derived from the outside diameter-side effective area Abf and the outside diameter-side minimum bypass area Bb when the wastegate valve WV is open.

[0078] Therefore, the left-hand side of equation 3 above represents a value corresponding to the flow rate difference (flow rate difference of an open valve) between the inner-diameter flow rate of an open valve and the outer-diameter flow rate of an open valve. Similarly, the right-hand side of equation 3 represents a value corresponding to the flow rate difference (flow rate difference of a closed valve) between the inner-diameter flow rate of a closed valve and the outer-diameter flow rate of a closed valve. Therefore, equation 3 states the condition that the flow rate difference of an open valve is smaller than the flow rate difference of a closed valve.

[0079] For example, the flow rate cross-sectional areas of the inner diameter-side bypass flow path are 139a (see Fig. 4) of the comparative example and the outer diameter-side bypass flow path 139b (see Fig. 4) Essentially the same. That is, the inner diameter-side minimum bypass area Ba is essentially the same as the outer diameter-side minimum bypass area Bb. In this case, the left-hand side of the preceding equation 3 is equal to the right-hand side. Therefore, the flow rate difference of an open valve is not substantially different from the flow rate difference of a closed valve. As described above, because the turbine casing 105 of the comparative example does not satisfy the condition of the preceding equation 3, it is difficult to reduce the fluctuations in the engine back pressure while the wastegate valve WV is open.

[0080] On the other hand, the inner diameter-side minimum bypass area Ba of the present embodiment is smaller than the outer diameter-side minimum bypass area Bb. In this embodiment, the first minimum exhaust area Aa is larger than the second minimum exhaust area Ab. The inner diameter-side constriction area Aia and the outer diameter-side constriction area Aib are approximately equal. Therefore, the inner diameter-side effective area Aaf is larger than the outer diameter-side effective area Abf. In this embodiment, the left-hand side of Equation 3 above is smaller than the right-hand side. Therefore, the flow rate difference of an open valve is smaller than the flow rate difference of a closed valve. As described above, it is possible to reduce the fluctuations of the engine back pressure while the wastegate valve WV is open because the turbine housing 5 of the present embodiment satisfies the condition of Equation 3 above.

[0081] It should be noted that there are cases where the left side of equation 3 above is larger than the right side, specifically where the minimum bypass area Ba on the inner diameter side is smaller than the minimum bypass area Bb on the outer diameter side. In this case, the flow rate difference of an open valve is greater than the flow rate difference of a closed valve. Consequently, fluctuations in the engine back pressure can be adversely affected when the wastegate valve WV is open compared to a closed state. Therefore, in the turbine housing 5 of the present embodiment, it is preferable to define the flow path cross-sectional areas to satisfy the condition of equation 3 above.

[0082] As described above, it is possible to safely reduce the fluctuations of the engine back pressure while the wastegate valve WV is open because the turbine housing 5 of the present embodiment satisfies the condition of the preceding equation 3.

[0083] Although the embodiment of the present invention has been described with reference to the accompanying drawings, it is understood that the present invention is not limited to the aforementioned embodiment. It is evident that those skilled in the art may conceive of various modifications or variations within the scope described in the claims, and it is understood that these are also within the technical scope of the present invention.

[0084] For example, the preceding embodiment described an example in which the turbine T is contained within the turbocharger TC. However, the present invention is not limited to this, and the turbine T may be contained in a device separate from the turbocharger TC, or may be a separate body.

[0085] In the present embodiment, the example described is one in which the first minimum exhaust area Aa is larger than the second minimum exhaust area Ab. However, the present invention is not limited to this, and the first minimum exhaust area Aa can be smaller than the second minimum exhaust area Ab.

[0086] Fig. Figure 7 is a sectional view along line AA of a turbine casing 205, a variation. As in Fig.As shown in Figure 7, the turbine housing 205 comprises an exhaust gas flow path 129 and a bypass flow path 239. The exhaust gas flow path 129 comprises an inner diameter-side exhaust gas flow path 129a and an outer diameter-side exhaust gas flow path 129b. The inner diameter-side exhaust gas flow path 129a comprises an inner diameter-side turbine spiral flow path 133a. The outer diameter-side exhaust gas flow path 129b comprises an outer diameter-side turbine spiral flow path 133b. In this modified version, the turbine housing 205 has the same structure as that of the turbine housing 5 in the preceding embodiment, except for the inner diameter-side turbine spiral flow path 133a, the outer diameter-side turbine spiral flow path 133b, and the bypass flow path 239.

[0087] In this case, the outer diameter-side turbine spiral flow path 133b has a greater flow path length than the inner diameter-side turbine spiral flow path 133a. This means that the outer diameter-side exhaust gas flow path 129b has a greater flow path length than the inner diameter-side exhaust gas flow path 129a. Consequently, the outer diameter-side exhaust gas flow path 129b has a greater pressure drop than the inner diameter-side exhaust gas flow path 129a. Therefore, it is preferable for the outer diameter-side exhaust gas flow path 129b to have a larger flow path cross-sectional area than the inner diameter-side exhaust gas flow path 129a.

[0088] Therefore, in the modified turbine housing 205, the flow path cross-sectional area of ​​the outer diameter-side exhaust gas flow path (first exhaust gas flow path) 129b is larger than the flow path cross-sectional area of ​​the inner diameter-side exhaust gas flow path (second exhaust gas flow path) 129a. That is, the second minimum exhaust gas area Ab is larger than the first minimum exhaust gas area Aa. As described above, the flow path cross-sectional area of ​​the one with the longer flow path length under the inner diameter-side exhaust gas flow path 129a and the outer diameter-side exhaust gas flow path 129b can be larger than that of the one with the shorter flow path length under the inner diameter-side exhaust gas flow path 129a and the outer diameter-side exhaust gas flow path 129b.As a result, it is possible to reduce the pressure loss of the one that has a larger flow path length, under the inner diameter-side exhaust gas flow path 129a and the outer diameter-side exhaust gas flow path 129b.

[0089] The bypass flow path 239 of the modification has an inner-diameter-side bypass flow path 239a and an outer-diameter-side bypass flow path 239b. The cross-sectional area of ​​the inner-diameter-side bypass flow path (second bypass flow path) 239a is larger than the cross-sectional area of ​​the outer-diameter-side bypass flow path (first bypass flow path) 239b. More precisely, an inner-diameter-side minimum bypass area Ba, which is the smallest cross-sectional area of ​​the inner-diameter-side bypass flow path 239a, is larger than an outer-diameter-side minimum bypass area Bb, which is the smallest cross-sectional area of ​​the outer-diameter-side bypass flow path 239b.This means that in the turbine housing 205, the cross-sectional area of ​​the flow path 129b on the outer diameter side is comparatively larger than that of the inner diameter side exhaust gas flow path 129a. Conversely, in the turbine housing 205, the cross-sectional area of ​​the flow path 239b on the outer diameter side bypass flow path is comparatively smaller than that of the inner diameter side bypass flow path 239a. It should be noted that the cross-sectional area of ​​the flow path 239 of both the exhaust gas flow path 129 and the bypass flow path 239 can be determined to satisfy the condition of Equation 3 above. Consequently, the modified turbine housing 205 can achieve effects similar to those of the preceding embodiment. Commercial applicability

[0090] The present invention is applicable to a turbine. Reference symbol list 5 Turbine housings (casings) 15 Turbine wheel 25 Exhaust flow path 27 recording units 29a inner diameter side exhaust gas flow path (first exhaust gas flow path) 29b outer diameter side exhaust gas flow path (second exhaust gas flow path) 39a Inner diameter-side bypass flow path (first bypass flow path) 39b Outer diameter-side bypass flow path (second bypass flow path) 45a first tongue 45b second tongue 129a inner diameter side exhaust gas flow path (second exhaust gas flow path) 129b Outer diameter side exhaust gas flow path (first exhaust gas flow path) 239a Inner diameter-side bypass flow path (second bypass flow path) 239b Outer diameter-side bypass flow path (first bypass flow path) Aa first minimum exhaust area From the second minimum exhaust area Aaf inner diameter side effective area (first effective area) Effective area on the outer diameter side (second effective area) Ai Total constriction area Aia inner diameter-side constriction area Aib outer diameter-side constriction area Ba inner diameter side minimum bypass area (first minimum bypass area) Bb outer diameter-side minimum bypass area (second minimum bypass area) T Turbine

Claims

[1] Turbine (T), with: a housing (5) in which a receiving unit (27) for receiving a turbine impeller (15) is formed; a first exhaust gas flow path (29a, 129b) which is formed in the housing (5) and is connected to the receiving unit (27); a second exhaust gas flow path (29b, 129a) formed in the housing (5) and connected to the receiving unit (27) at a position which differs in a circumferential direction of the turbine impeller (15) from a position where the receiving unit (27) and the first exhaust gas flow path (29a, 129b) are connected, wherein the second exhaust gas flow path (29b, 129a) has a flow path cross-sectional area which is smaller than a flow path cross-sectional area of ​​the first exhaust gas flow path (29a, 129b); an exhaust flow path (25) which is formed in the housing (5) and is connected to the receiving unit (27) in an axial direction of the turbine impeller (15); a first bypass flow path (39a, 239b) that connects the first exhaust flow path (29a, 129b) and the discharge flow path (25); a second bypass flow path (39b, 239a) connecting the second exhaust flow path (29b, 129a) and the discharge flow path (25), wherein the second bypass flow path (39b, 239a) has a flow path cross-sectional area larger than a flow path cross-sectional area of ​​the first bypass flow path (39a, 239b), a first tongue (45a, 45b) that separates the first exhaust gas flow path (29a, 129b) and the second exhaust gas flow path (29b, 129a), wherein the first tongue (45a, 45b) is contained at a position in the housing (5) opposite a downstream end of the first exhaust gas flow path (29a, 129b); and a second tongue (45b, 45a) that separates the second exhaust gas flow path (29b, 129a) and the first exhaust gas flow path (29a, 129b), wherein the second tongue (45b, 45a) is contained at a position in the housing (5) opposite a downstream end of the second exhaust gas flow path (29b, 129a), wherein the flow path cross-sectional area of ​​the first exhaust gas flow path (29a, 129b) is a first minimum exhaust gas area Aa, where the flow path cross-sectional area is smallest in a section of the first exhaust gas flow path (29a, 129b) opposite the second tongue (45b), the flow path cross-sectional area of ​​the second exhaust gas flow path (29b, 129a) is a second minimum exhaust gas area Ab, where the flow path cross-sectional area is smallest in a section of the second exhaust gas flow path (29b, 129a) opposite the first tongue (45a), the flow path cross-sectional area of ​​the first bypass flow path (39a, 239b) is a first minimum bypass area Ba, where the flow path cross-sectional area in the first bypass flow path (39a, 239b) is smallest, the flow path cross-sectional area of ​​the second bypass flow path (39b, 239a) is a second minimum bypass area Bb, where the flow path cross-sectional area in the second bypass flow path (39b, 239a) is smallest, and, compared to a difference between a first effective area Aaf, derived from the first minimum exhaust area Aa and a constriction area of ​​the turbine impeller (15), and a second effective area Abf, derived from the second minimum exhaust area Ab and a constriction area of ​​the turbine impeller (15), a difference between a sum of the first effective area Aaf and the first minimum bypass area Ba and a sum of the second effective area Abf and the second minimum bypass area Bb is smaller. [2] Turbine (T) according to claim 1, wherein the second exhaust gas flow path (29b) has a greater length than the length of the first exhaust gas flow path (29a). [3] Turbine (T) according to claim 1, wherein the first exhaust gas flow path (129b) has a greater length than the length of the second exhaust gas flow path (129a). [4] Turbine (T) according to any one of claims 1 to 3, wherein, where the first minimum exhaust area is designated by Aa, the second minimum exhaust area is designated by Ab, a total constriction area of ​​the turbine impeller (15) is designated by Ai, a constriction area of ​​an opposite section of the turbine impeller (15) facing the first exhaust flow path (29a, 129b) is designated by Aia, a constriction area of ​​an opposite section of the turbine impeller (15) facing the second exhaust flow path (29b, 129a) is designated by Aib, a central angle of the opposite section of the turbine impeller (15) facing the first exhaust flow path (29a, 129b) is designated by θa, a central angle of the opposite section of the turbine impeller (15) facing the second exhaust flow path (29b, 129a) is designated by θa. 129a) opposite, is designated by θb, the first effective area is designated by Aaf,and the second effective area is denoted by Abf, the first effective area Aaf is derived from equation (1) and equation (1a), and the second effective area Abf is derived from equation (2) and equation (2a): , Aaf=Aa⋅AiaAa2+Aia2 Aia=Ai⋅θaθa+θb Abf=Ab⋅AibAb2+Aib2 Aib=Ai⋅θbθa+θb

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