Turbine and turbocharger

Abstract

A turbine is provided, comprising: a first turbine scroll flow passage (31) extending on a radially outer side around a turbine runner (17) and communicating with a receiving portion (29); a second turbine scroll flow passage (33) extending on the radially outer side around the turbine runner (17), communicating with the receiving portion (29), and disposed on a discharge flow passage side with respect to the first turbine scroll flow passage (31); a partition plate (35) configured to divide the first turbine scroll flow passage (31) and the second turbine scroll flow passage (33) in the axial direction; a first tongue portion (43) provided at a position facing a downstream end of the first turbine scroll flow passage (31);and a second tongue portion (51) provided at a position facing a downstream end of the second turbine scroll flow passage (33), wherein a radial distance between an end portion (51a) of the second tongue portion (51) on a side of the partition plate (35) and the turbine runner (17) is different from a radial distance between an end portion (43a) of the first tongue portion (43) on the side of the partition plate (35) and the turbine runner (17);

Description

Technical field

[0001] The present disclosure relates to a turbine and a turbocharger. State of the art

[0002] For example, as disclosed in Patent Literature 1, as a turbine provided in a turbocharger or the like, there is a turbine in which two turbine scroll flow passages extending on a radially outer side around a turbine runner are arranged side by side in an axial direction of the turbine runner. A tongue portion is provided at a position facing a downstream end of each of the turbine scroll flow passages. The turbine as described above is also called a twin-scroll type turbine. Citation listPatent literature

[0003] Patent Literature 1: JP 2006-348894 A SummaryTechnical problem

[0004] In a turbine equipped with a tongue section, such as a twin-screw turbine, aerodynamic performance increases as the distance between the tongue section and a turbine runner becomes shorter. However, as the distance between the tongue section and the turbine runner becomes shorter, the excitation force acting on the turbine runner increases, resulting in blade vibration being more likely to occur. Accordingly, it is desirable to reduce the blade vibration of the turbine runner to improve aerodynamic performance.

[0005] The present disclosure has an object to provide a turbine capable of reducing blade vibration of a turbine impeller and a turbocharger. Solution to the problem

[0006] To solve the above-mentioned problem, according to the present disclosure, there is provided a turbine comprising: an accommodating portion configured to accommodate a turbine runner; a discharge flow passage continuous with the accommodating portion in an axial direction of the turbine runner; a first turbine scroll flow passage extending around the turbine runner on a radially outer side and communicating with the accommodating portion; a second turbine scroll flow passage extending around the turbine runner on the radially outer side, communicating with the accommodating portion, and disposed on the discharge flow passage side with respect to the first turbine scroll flow passage; a partition plate configured to divide the first turbine scroll flow passage and the second turbine scroll flow passage in the axial direction;a first tongue portion provided at a position facing a downstream end of the first turbine scroll flow passage; and a second tongue portion provided at a position facing a downstream end of the second turbine scroll flow passage, wherein a radial distance between an end portion of the second tongue portion on the partition plate side and the turbine runner is different from a radial distance between an end portion of the first tongue portion on the partition plate side and the turbine runner.

[0007] The radial distance between the end portion of the second tongue portion on the dividing plate side and the turbine runner may be longer than the radial distance between the end portion of the first tongue portion on the dividing plate side and the turbine runner.

[0008] An average value of a radial distance between the second tongue portion and the turbine runner in the axial direction may be larger than an average value of a radial distance between the first tongue portion and the turbine runner in the axial direction.

[0009] A radial distance between at least one of the first tongue portion or the second tongue portion and the turbine runner may become longer as it extends toward the discharge flow passage side in the axial direction.

[0010] A radial distance between at least one of the first tongue portion or the second tongue portion and the turbine runner may become longer as it extends in a rotational direction of the turbine runner.

[0011] In order to solve the above-mentioned problem, according to the present disclosure, a turbocharger is provided which has the above-mentioned turbine. Advantageous effects of the invention

[0012] According to the present disclosure, it is possible to reduce blade vibration of the turbine runner. Brief description of the drawings Fig. 1 is a schematic sectional view illustrating a turbocharger according to an embodiment of the present disclosure. Fig. 2 is a sectional view taken along the line AA in Fig. 1 is taken. Fig. 3 is a sectional view taken along the line BB in Fig. 1 is taken. Fig. 4 is a sectional view taken along the line CC in Fig. 2 and Fig. 3 is taken. Fig. 5 is a sectional view showing a shape of a tongue portion in a first modification example. Fig. 6 is a sectional view showing a shape of the tongue portion in a second modification example. Description of the embodiments

[0013] Now, an embodiment of the present disclosure will be described with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values represented in the embodiment are merely examples used to facilitate understanding of the disclosure and, unless otherwise specifically noted, do not limit the present disclosure. Elements having substantially the same functions and configurations are denoted by the same reference numerals herein and in the drawings to omit redundant description thereof. Furthermore, illustration of elements not directly related to the present disclosure is omitted.

[0014] Fig. 1 is a schematic sectional view illustrating a turbocharger TC according to an embodiment of the present disclosure. A description will be given below while a direction indicated by the arrow L shown in Fig. 1, corresponds to a left side of the turbocharger TC. A direction indicated by the arrow R, which is shown in Fig. 1 corresponds to a 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 comprises a bearing housing 3, a turbine housing 5, and a compressor housing 7.

[0015] The turbine housing 5 is coupled to a left side of the bearing housing 3 by a fastening mechanism 9. The fastening mechanism 9 is, for example, a G-coupling. The compressor housing 7 is coupled to a right side of the bearing housing 3 by a fastening bolt 11. The turbocharger TC includes a turbine T and a centrifugal compressor C. The turbine T includes the bearing housing 3 and the turbine housing 5. The turbine T is a twin-screw type turbine. The centrifugal compressor C includes the bearing housing 3 and the compressor housing 7.

[0016] The bearing housing 3 has a bearing hole 3a formed therein. The bearing hole 3a extends through the bearing housing 3 in a right-and-left direction of the turbocharger TC. Bearings 13 are provided in the bearing hole 3a. Fig. 1, a fully floating bearing is shown as an example of the bearing 13. However, the bearing 13 may be another bearing, such as a partially floating bearing or a rolling bearing. The bearings 13 axially support a shaft 15 in a rotatable manner. A turbine impeller 17 is provided at a left end portion of the shaft 15. The turbine impeller 17 is housed in the turbine housing 5 so as to be rotatable. A compressor impeller 19 is provided at a right end portion of the shaft 15. The compressor impeller 19 is housed in the compressor housing 7 so as to be rotatable.

[0017] An axial direction, a radial direction, and a circumferential direction of the turbocharger TC are hereinafter referred to as "axial direction," "radial direction," and "circumferential direction." The axial direction of the turbocharger TC corresponds to an axial direction of the shaft 15, an axial direction of the turbine impeller 17, and an axial direction of the compressor impeller 19. The radial direction of the turbocharger TC corresponds to a radial direction of the shaft 15, a radial direction of the turbine impeller 17, and a radial direction of the compressor impeller 19. The circumferential direction of the turbocharger TC corresponds to a circumferential direction of the shaft 15, a circumferential direction of the turbine impeller 17, and a circumferential direction of the compressor impeller 19.

[0018] An intake port 21 is formed in the compressor housing 7. The intake port 21 is open on the right side of the turbocharger TC. The intake port 21 is connected to an air cleaner (not shown). A diffuser flow passage 23 is defined by opposing surfaces of the bearing housing 3 and the compressor housing 7. The diffuser flow passage 23 increases a pressure of air. The diffuser flow passage 23 has a circular ring shape. The diffuser flow passage 23 communicates with the intake port 21 through an interposition of the compressor impeller 19 on a radially inner side.

[0019] Further, a compressor scroll flow passage 25 is formed in the compressor housing 7. The compressor scroll flow passage 25 has a circular ring shape. The compressor scroll flow passage 25 is located, for example, on a radially outer side with respect to the diffuser flow passage 23. The compressor scroll flow passage 25 communicates with an intake port of an engine (not shown) and the diffuser flow passage 23. As the compressor impeller 19 rotates, the air is sucked from the intake port 21 into the compressor housing 7. The intake air is pressurized and accelerated as it flows through blades of the compressor impeller 19. The pressurized and accelerated air is increased in pressure in the diffuser flow passage 23 and the compressor scroll flow passage 25.The air, which has been increased in pressure, is led to the intake port of the engine.

[0020] A discharge flow passage 27, a receiving portion 29, a first turbine scroll flow passage 31, and a second turbine scroll flow passage 33 are formed in the turbine housing 5. The discharge flow passage 27 is opened on the left side of the turbocharger TC. The discharge flow passage 27 is connected to an exhaust gas purification device (not shown). The discharge flow passage 27 communicates with the receiving portion 29. The discharge flow passage 27 is continuous with the receiving portion 29 in the axial direction. The receiving portion 29 receives the turbine impeller 17. The first turbine scroll flow passage 31 and the second turbine scroll flow passage 33 are provided on a radially outer side with respect to the receiving portion 29.

[0021] The first turbine scroll flow passage 31 and the second turbine scroll flow passage 33 extend around the turbine runner 17 on a radially outer side. The first turbine scroll flow passage 31 and the second turbine scroll flow passage 33 communicate with the receiving portion 29. The second turbine scroll flow passage 33 is arranged on the discharge flow passage 27 side with respect to the first turbine scroll flow passage 31 in the axial direction. A partition plate 35 is formed between the first turbine scroll flow passage 31 and the second turbine scroll flow passage 33. The partition plate 35 divides the first turbine scroll flow passage 31 and the second turbine scroll flow passage 33 in the axial direction.The first turbine scroll flow passage 31 and the second turbine scroll flow passage 33 communicate with an exhaust manifold of the engine (not shown). Exhaust gas discharged from the exhaust manifold of the engine (not shown) is guided to the discharge flow passage 27 after the exhaust gas is conveyed to the receiving portion 29 through the first turbine scroll flow passage 31 and the second turbine scroll flow passage 33. The exhaust gas, which is guided to the discharge flow passage 27 in the process of flowing, causes the turbine runner 17 to rotate.

[0022] The rotational force of the turbine impeller 17 is transmitted through the shaft 15 to the compressor impeller 19. As the compressor impeller 19 rotates, the air pressure increases as described above. Thus, the air is supplied to the intake port of the engine.

[0023] Fig. 2 is a sectional view taken along the line AA in Fig. 1. The section AA is a section perpendicular to the axial direction of the shaft 15 and passing through the first turbine screw flow passage 31. In Fig. 2, the turbine impeller 17 is illustrated in such a way that only an outer circumference thereof, indicated by a circle, is shown.

[0024] As in Fig. 2, a first exhaust gas introduction port 37 is formed in the turbine housing 5. The first exhaust gas introduction port 37 is opened to the outside of the turbine housing 5. The exhaust gas discharged from the exhaust manifold of the engine (not shown) is introduced into the first exhaust gas introduction port 37.

[0025] A first exhaust gas introduction passage 39 is formed between the first exhaust gas introduction port 37 and the first turbine scroll flow passage 31. The first exhaust gas introduction passage 39 connects the first exhaust gas introduction port 37 and the first turbine scroll flow passage 31. The first exhaust gas introduction port 39 is formed, for example, in a straight shape. The first exhaust gas introduction passage 39 guides the exhaust gas introduced from the first exhaust gas introduction port 37 to the first turbine scroll flow passage 31.

[0026] The first turbine scroll flow passage 31 communicates with the receiving portion 29 through a first connecting portion 41. The first connecting portion 41 is formed in a circular ring shape over the entire circumference of the receiving portion 29. The first turbine scroll flow passage 31 guides the exhaust gas introduced from the first exhaust introduction passage 39 to the receiving portion 29 through the first connecting portion 41. The first turbine scroll flow passage 31 extends around the turbine runner 17 so as to be closer to the turbine runner 17 when extending in a rotational direction RD of the turbine runner 17. A width of the first turbine scroll flow passage 31 in the radial direction decreases from an upstream side to a downstream side.

[0027] A first tongue portion 43 is provided at a position facing a downstream end of the first turbine scroll flow passage 31. The first tongue portion 43 divides a downstream portion and an upstream portion of the first turbine scroll flow passage 31.

[0028] Fig. 3 is a sectional view taken along the line BB in Fig. 1. The section BB is a section perpendicular to the axial direction of the shaft 15 and passing through the second turbine screw flow passage 33. In Fig. 3, the turbine wheel 17 is to be arranged in a similar manner Fig. 2 is shown in such a way that only an outer circumference thereof, indicated by a circle, is shown.

[0029] As in Fig. 3, a second exhaust gas introduction port 45 is formed in the turbine housing 5. The second exhaust gas introduction port 45 is open to the outside of the turbine housing 5. The second exhaust gas introduction port 45 is arranged on the discharge flow passage 27 side with respect to the first exhaust gas introduction port 37 in the axial direction. The first exhaust gas introduction port 37 and the second exhaust gas introduction port 45 are divided in the axial direction by the partition plate 35. The exhaust gas discharged from the exhaust manifold of the engine (not shown) is introduced into the second exhaust gas introduction port 45.

[0030] A second exhaust introduction passage 47 is formed between the second exhaust introduction port 45 and the second turbine scroll flow passage 33. The second exhaust introduction passage 47 connects the second exhaust introduction port 45 and the second turbine scroll flow passage 33. The second exhaust introduction passage 47 is formed, for example, in a straight shape. The second exhaust introduction passage 47 is arranged on the discharge flow passage 27 side with respect to the first exhaust introduction passage 39 in the axial direction. The first exhaust introduction passage 39 and the second exhaust introduction passage 47 are divided in the axial direction by the partition plate 35. The second exhaust introduction passage 47 guides the exhaust gas introduced from the second exhaust introduction port 45 to the second turbine scroll flow passage 33.

[0031] The second turbine scroll flow passage 33 communicates with the receiving portion 29 through a second connecting portion 49. The second connecting portion 49 is formed in a circular ring shape over the entire circumference of the receiving portion 29. The second connecting portion 49 is arranged on the discharge flow passage 27 side with respect to the first connecting portion 41 in the axial direction. The first connecting portion 41 and the second connecting portion 49 are divided in the axial direction by the partition plate 35. The second turbine scroll flow passage 33 guides the exhaust gas introduced from the second exhaust introduction passage 47 to the receiving portion 29 through the second connecting portion 49. The second turbine scroll flow passage 33 extends around the turbine runner 17 so as to be closer to the turbine runner 17 when extending in the rotational direction RD of the turbine runner 17.A width of the second turbine scroll flow passage 33 in the radial direction decreases from an upstream side to a downstream side.

[0032] A second tongue portion 51 is provided at a position facing a downstream end of the second turbine scroll flow passage 33. The second tongue portion 51 divides a downstream portion and an upstream portion of the second turbine scroll flow passage 33. A circumferential direction position of the first tongue portion 43 and a circumferential direction position of the second tongue portion 51 coincide with each other. However, the circumferential direction position of the first tongue portion 43 and the circumferential direction position of the second tongue portion 51 may be different from each other.

[0033] Fig. 4 is a sectional view taken along the line CC in Fig. 2 and Fig. 3. The section CC is a section passing through the first tongue portion 43 and the second tongue portion 51 and having an axis of rotation of the turbine impeller 17.

[0034] As in Fig. 4, the turbine runner 17 has a plurality of blade bodies 17a. The plurality of blade bodies 17a are provided at intervals in the circumferential direction. Each of the blade bodies 17a is formed to extend radially outward from an outer peripheral surface of a hub extending on the rotational axis of the turbine runner 17. In one example of Fig. 4, a leading edge LE of the blade body 17a extends parallel to the rotation axis of the turbine runner 17. However, the leading edge LE may be inclined toward the radially outer side when extending toward the discharge flow passage 27 side in the axial direction. The leading edge LE is a portion of an outer peripheral edge of the blade body 17a that opposes the first turbine scroll flow passage 31 and the second turbine scroll flow passage 33. Exhaust gas flows from the first turbine scroll flow passage 31 and the second turbine scroll flow passage 33 into the leading edge LE.

[0035] The first tongue portion 43 and the second tongue portion 51 are arranged on a radially outer side with respect to the leading edge LE of the blade body 17a of the turbine wheel 17. In the example of Fig. 4, portions of the first tongue portion 43 and the second tongue portion 51 facing the turbine runner 17 extend parallel to the rotational axis of the turbine runner 17. That is, the portions of the first tongue portion 43 and the second tongue portion 51 facing the turbine runner 17 extend parallel to the leading edge LE. If the first tongue portion 43 and the second tongue portion 51 are not specifically distinguished from each other, the first tongue portion 43 and the second tongue portion 51 are hereinafter simply referred to as "tongue portions."

[0036] A radial distance between the tongue portion and the turbine runner 17 is a difference between a distance from a center axis of the turbine runner 17 to the tongue portion and a maximum radius of the turbine runner 17. That is, the radial distance between the tongue portion and the turbine runner 17 is a distance between the tongue portion and the leading edge LE at the time when each of the blade bodies 17a is closest to each tongue portion. In the example of Fig. 4, for both the first tongue portion 43 and the second tongue portion 51, the radial distance between the tongue portion and the turbine runner 17 is constant regardless of axial position. However, for at least one of the first tongue portion 43 or the second tongue portion 51, the radial distance between the tongue portion and the turbine runner 17 may vary depending on the axial position. Fig. 4 shows a radial distance D1 between the first tongue portion 43 and the turbine runner 17 and a radial distance D2 between the second tongue portion 51 and the turbine runner 17.

[0037] As in Fig. 4, a radial distance between an end portion 43a of the first tongue portion 43 on the side of the partition plate 35 and the turbine runner 17 and a radial distance between an end portion 51a of the second tongue portion 51 on the side of the partition plate 35 and the turbine runner 17 are different from each other. In the example of Fig. 4, the radial distance between the end portion 51a of the second tongue portion 51 on the partition plate 35 side and the turbine runner 17 is longer than the radial distance between the end portion 43a of the first tongue portion 43 on the partition plate 35 side and the turbine runner 17. Accordingly, the radial distance D2 between the second tongue portion 51 and the turbine runner 17 is longer than the radial distance D1 between the first tongue portion 43 and the turbine runner 17. That is, an average value of the radial distance between the second tongue portion 51 and the turbine runner 17 in the axial direction is larger than an average value of the radial distance between the first tongue portion 43 and the turbine runner 17 in the axial direction.

[0038] Aerodynamic performance becomes higher as the average value of the radial distance between the tongue portion and the turbine runner 17 in the axial direction becomes smaller. Meanwhile, an exciting force acting on the turbine runner 17 becomes larger, with the result that blade vibration is more likely to occur. In this embodiment, as described above, the radial distance between the end portion 43a of the first tongue portion 43 on the partition plate 35 side and the turbine runner 17 and the radial distance between the end portion 51a of the second tongue portion 51 on the partition plate 35 side and the turbine runner 17 are different from each other. Accordingly, a radial position of the entire first tongue portion 43 and a radial position of the entire second tongue portion 51 can be individually selected.Thus, between the first tongue portion 43 and the second tongue portion 51, it may be easy to vary the average values of the radial distances between the tongue portions and the turbine impeller 17 in the axial direction.

[0039] Thus, the average value of the radial distance between the tongue portion and the turbine runner 17 in the axial direction can be reduced for one of the first tongue portion 43 and the second tongue portion 51, while the average value of the radial distance between the tongue portion and the turbine runner 17 in the axial direction is increased for another of the first tongue portion 43 and the second tongue portion 51. Thus, compared to a case where the average value of the radial distance between the tongue portion and the turbine runner 17 in the axial direction is uniformly decreased or increased, the excitation force acting on the turbine runner 17 can be reduced for both the first tongue portion 43 and the second tongue portion 51.Furthermore, in accordance with the reduction of the excitation force, the radial distance between the tongue portion and the turbine impeller 17 is made smaller and thus aerodynamic performance can also be improved.

[0040] Furthermore, in a case where the radial distance between the tongue portion and the turbine runner 17 is short, an area of a flow passage formed by the blade body 17a and the tongue portion is immediately narrowed when the blade body 17a of the turbine runner 17 passes through the vicinity of the tongue portion, thereby causing flow contraction of gas. As a result, a circumferential component of the gas flow velocity in the vicinity of the tongue portion increases, and thus a separation vortex is more likely to be generated at the leading edge LE. The generation of such a separation vortex acts as a flow barrier within the flow passage of the turbine runner 17 and generates a local high-pressure region on the discharge flow passage 27 side of the blade body 17a. Such a high-pressure region is the source of the exciting force.Such a source of excitation force is a factor that increases blade vibration. Specifically, the vibration is more likely to occur on the leading edge LE discharge flow passage 27 side, which is more susceptible to the excitation force, compared to a side of the leading edge LE opposite to the discharge flow passage 27 side. Thus, when the gas flow is compressed on the leading edge LE discharge flow passage 27 side, blade vibration is particularly likely to increase.

[0041] In this embodiment, as described above, the radial distance between the end portion 51a of the second tongue portion 51 on the partition plate 35 side and the turbine runner 17 is longer than the radial distance between the end portion 43a of the first tongue portion 43 on the partition plate 35 side and the turbine runner 17. Accordingly, an average value of the radial distance between the second tongue portion 51 and the turbine runner 17 in the axial direction can be made larger than the average value of the radial distance between the first tongue portion 43 and the turbine runner 17 in the axial direction. This enables an increase in the area of the flow passage directly formed by the blade body 17a and the tongue portion.Thus, the degree to which the gas flow is compressed on the discharge flow passage 27 side of the leading edge LE can be reduced, and thus the increase in blade vibration of the turbine impeller 17 can be appropriately suppressed.

[0042] A description has been given above of the example in which the radial distance between the end portion 51a of the second tongue portion 51 on the partition plate 35 side and the turbine runner 17 is longer than the radial distance between the end portion 43a of the first tongue portion 43 on the partition plate 35 side and the turbine runner 17. However, the radial distance between the end portion 51a of the second tongue portion 51 on the partition plate 35 side and the turbine runner 17 may be shorter than the radial distance between the end portion 43a of the first tongue portion 43 on the partition plate 35 side and the turbine runner 17. Furthermore, the average value of the radial distance between the second tongue portion 51 and the turbine runner 17 in the axial direction may be smaller than the average value of the radial distance between the first tongue portion 43 and the turbine runner 17 in the axial direction.

[0043] Furthermore, the description has been given above of the example in which the radial distance between the end portion 51a of the second tongue portion 51 and the turbine runner 17 is longer than the radial distance between the end portion 43a of the first tongue portion 43 and the turbine runner 17, and the average value of the radial distance between the second tongue portion 51 and the turbine runner 17 in the axial direction is larger than the average value of the radial distance between the first tongue portion 43 and the turbine runner 17 in the axial direction.However, it may be configured such that the radial distance between the end portion 51a of the second tongue portion 51 and the turbine runner 17 is shorter than the radial distance between the end portion 43a of the first tongue portion 43 and the turbine runner 17, and the average value of the radial distance between the second tongue portion 51 and the turbine runner 17 in the axial direction is larger than the average value of the radial distance between the first tongue portion 43 and the turbine runner 17 in the axial direction.Further, it may be configured that the radial distance between the end portion 51a of the second tongue portion 51 and the turbine runner 17 is longer than the radial distance between the end portion 43a of the first tongue portion 43 and the turbine runner 17, and the average value of the radial distance between the second tongue portion 51 and the turbine runner 17 in the axial direction is smaller than the average value of the radial distance between the first tongue portion 43 and the turbine runner 17 in the axial direction.

[0044] Fig. 5 is a sectional view showing a shape of the tongue portion in a first modification example. Fig. 5 is a sectional view at a section passing through the first tongue portion 43 and the second tongue portion 51 and having a rotation axis of the turbine runner 17. In the first modification example, a shape of the first tongue portion 43 and a shape of the second tongue portion 51 are different from those of the embodiment described above with reference to FIG. Fig. 1 to Fig. 4 is described.

[0045] As in Fig. 5, in the first modification example, the radial distance between the tongue portion and the turbine runner 17 becomes longer for both the first tongue portion 43 and the second tongue portion 51 when extending to the discharge flow passage 27 side in the axial direction. In the example of Fig. 5, the first tongue portion 43 and the second tongue portion 51 are inclined toward a radially outer side when extending toward the discharge flow passage 27 side in the axial direction. Portions of the first tongue portion 43 and the second tongue portion 51 facing the turbine runner 17 are straight when viewed in the circumferential direction. However, the portions of the first tongue portion 43 and the second tongue portion 51 facing the turbine runner 17 may be curved when viewed in the circumferential direction.

[0046] In the first modification example, as described above, the radial distance between the tongue portion and the turbine runner 17 becomes longer when extending to the discharge flow passage 27 side in the axial direction for both the first tongue portion 43 and the second tongue portion 51. Accordingly, it is possible to reduce the degree to which the gas flow is compressed at the leading edge LE when extending to the discharge flow passage 27 side in the axial direction. Thus, the increase in blade vibration of the turbine runner 17 can be appropriately suppressed.

[0047] A description has been given above of the example in which the radial distance between the tongue portion and the turbine runner 17 becomes longer when extending to the discharge flow passage 27 side in the axial direction for both the first tongue portion 43 and the second tongue portion 51. However, the radial distance between the tongue portion and the turbine runner 17 may become longer when extending to the discharge flow passage 27 side in the axial direction for only one of the first tongue portion 43 and the second tongue portion 51. When the radial distance between at least one of the first tongue portion 43 or the second tongue portion 51 and the turbine runner 17 becomes longer when extending to the discharge flow passage 27 side in the axial direction, the same effect as that in the above-mentioned example is achieved.

[0048] The radial distance between at least one of the first tongue portion 43 or the second tongue portion 51 and the turbine runner 17 may become shorter as it extends to the discharge flow passage 27 side in the axial direction.

[0049] In the example of Fig. 5, the radial distance between the end portion 51a of the second tongue portion 51 on the partition plate 35 side and the turbine runner 17 is longer than the radial distance between the end portion 43a of the first tongue portion 43 on the partition plate 35 side and the turbine runner 17. However, in the first modification example, the radial distance between the end portion 51a of the second tongue portion 51 on the partition plate 35 side and the turbine runner 17 may be shorter than the radial distance between the end portion 43a of the first tongue portion 43 on the partition plate 35 side and the turbine runner 17.

[0050] Fig. 6 is a sectional view showing a shape of the tongue portion in a second modification example. Fig. 6 is a sectional view taken at a section perpendicular to the axial direction of the shaft 15 and passing through the first screw flow passage 31. In the second modification example, the shape of the first tongue portion 43 is different from that in the embodiment described above with reference to FIG. Fig. 1 to Fig. 4 is described.

[0051] As in Fig. 6, in the second modification example, the radial distance between the first tongue portion 43 and the turbine runner 17 becomes longer when extending in the rotational direction RD of the turbine runner 17. In the example of Fig.6, a radial position of an opposing surface 43b of the first tongue portion 43 facing the turbine impeller 17 is displaced radially outward as the opposing surface 43b extends in the rotational direction RD. An end portion 43c of the opposing surface 43b on a side toward the rotational direction RD is located further on the radially outer side than an end portion 43d of the opposing surface 43b on a side opposite to the rotational direction RD. The opposing surface 43b is curved when viewed in the axial direction. However, the opposing surface 43b may be straight when viewed in the axial direction.

[0052] In the second modification example, as described above, the radial distance between the first tongue portion 43 and the turbine runner 17 becomes longer as it extends in the rotational direction RD of the turbine runner 17. Accordingly, it is possible to reduce the degree to which the gas flow is compressed by the blade body 17a and the first tongue portion 43 at the time when the blade body 17a of the turbine runner 17 passes through the vicinity of the first tongue portion 43. Thus, generation of a separation vortex in the vicinity of the first tongue portion 43 is suppressed, and the blade vibration of the turbine runner 17 is thus further effectively reduced.

[0053] A description has been given above of the example in which the radial distance between the first tongue portion 43 and the turbine runner 17 becomes longer as it extends in the rotational direction RD of the turbine runner 17. However, the radial distance between the tongue portion and the turbine runner 17 may become longer for both the first tongue portion 43 and the second tongue portion 51 as it extends in the rotational direction RD of the turbine runner 17. The radial distance between the tongue portion and the turbine runner 17 may become longer for only one of the first tongue portion 43 and the second tongue portion 51 as it extends in the rotational direction RD of the turbine runner 17.When the radial distance between at least one of the first tongue portion 43 or the second tongue portion 51 and the turbine runner 17 becomes longer when extending in the rotational direction RD of the turbine runner 17, the same effect as that in the above-mentioned example is achieved.

[0054] The radial distance between at least one of the first tongue portion 43 or the second tongue portion 51 and the turbine runner 17 may be constant regardless of the circumferential position. The radial distance between at least one of the first tongue portion 43 or the second tongue portion 51 and the turbine runner 17 may become shorter as it extends in the rotational direction RD of the turbine runner 17.

[0055] An embodiment of the present disclosure has been described above with reference to the accompanying drawings, but it should be understood that the present disclosure is not limited to the above-mentioned embodiment. It is apparent that a person skilled in the art can devise various modifications and variations within the scope of the claims, and those examples are understood to fall within the technical scope of the present disclosure.

[0056] A description has been given above of the example in which the turbine T is mounted on the turbocharger TC. However, the turbine T may be mounted on devices (e.g., a power generator) other than the turbocharger TC.

[0057] The present disclosure accelerates both an improvement in aerodynamic performance and a reduction in blade vibration of turbine rotors. Thus, the present disclosure can contribute, for example, to Sustainable Development Goal (SDG) Goal 7 "Ensure access to affordable, reliable, and modern energy for all" and Goal 9 "Build sustainable infrastructure, promote inclusive and sustainable industrialization, and foster innovation." List of reference symbols

[0058] 17: Turbine runner, 27: Discharge flow passage, 29: Receiving section, 31: First turbine scroll flow passage, 33: Second turbine scroll flow passage, 35: Dividing plate, 43: First tongue section, 43a: End section, 51: Second tongue section, 51a: End section, RD: Rotation direction, T: Turbine, TC: Turbocharger QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2006-348894 A

[0003]

Claims

[1] Turbine with: a receiving portion configured to receive a turbine impeller; a discharge flow passage continuous with the receiving portion in an axial direction of the turbine impeller; a first turbine scroll flow passage extending around the turbine runner on a radially outer side and communicating with the receiving portion; a second turbine scroll flow passage extending around the turbine runner on the radially outer side, communicating with the receiving portion, and disposed on the discharge flow passage side with respect to the first turbine scroll flow passage; a partition plate configured to partition the first turbine scroll flow passage and the second turbine scroll flow passage in the axial direction; a first tongue portion provided at a position facing a downstream end of the first turbine scroll flow passage; and a second tongue portion provided at a position facing a downstream end of the second turbine scroll flow passage, wherein a radial distance between an end portion of the second tongue portion on the partition plate side and the turbine runner is different from a radial distance between an end portion of the first tongue portion on the partition plate side and the turbine runner. [2] The turbine according to claim 1, wherein the radial distance between the end portion of the second tongue portion on the side of the partition plate and the turbine runner is longer than the radial distance between the end portion of the first tongue portion on the side of the partition plate and the turbine runner. [3] The turbine according to claim 1 or 2, wherein an average value of a radial distance between the second tongue portion and the turbine runner in the axial direction is larger than an average value of a radial distance between the first tongue portion and the turbine runner in the axial direction. [4] The turbine according to any one of claims 1 to 3, wherein a radial distance between at least one of the first tongue portion or the second tongue portion and the turbine impeller becomes longer as it extends toward the discharge flow passage side in the axial direction. [5] The turbine according to any one of claims 1 to 4, wherein a radial distance between at least one of the first tongue portion or the second tongue portion and the turbine runner becomes longer as it extends in a rotational direction of the turbine runner. [6] Turbocharger with the turbine according to one of claims 1 to 5.

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