Turbines and turbochargers

Abstract

This turbine comprises: a first housing that has a scroll channel; a turbine wheel provided on an inner circumferential side of the scroll channel; a first plate-shaped member including an annular first plate section; a second plate-shaped member including an annular second plate section that is disposed facing the first plate section farther on a leading-end side than the first plate section in the axial direction and that forms a gas channel from the scroll channel toward the turbine wheel between the first plate section and the second plate section; at least one variable nozzle vane disposed in the gas channel and rotatably supported by the first plate-shaped member or the second plate-shaped member; a second housing that is disposed farther on the rear-end side than the first plate-shaped member in the axial direction; a rear-end-side biasing member disposed between the second housing and the first plate-shaped member and configured to bias the first plate section toward the gas channel side; and at least one support member provided to the gas channel, having one end connected to the plate section of one of the first plate section and the second plate section, and having the other end abutting against the other plate section of the first plate section and the second plate section.

Description

[Technical Field]

[0001] The present disclosure relates to turbines and turbochargers. [Background technology]

[0002] Known turbochargers (superchargers) that supercharge the intake air of an internal combustion engine by utilizing the energy of the exhaust gas from the engine include those equipped with variable geometry turbines (see, for example, Patent Document 1). A variable geometry turbine has a plurality of nozzle vanes arranged in the circumferential direction of the turbine wheel in an exhaust gas passage that sends exhaust gas from the turbine's scroll passage to the turbine wheel, and the blade angle of these nozzle vanes can be changed externally by an actuator to adjust the flow path cross-sectional area of the exhaust gas passage (the flow path between adjacent nozzle vanes). A variable geometry turbine adjusts the flow path cross-sectional area of the exhaust gas passage to change the flow velocity and pressure of the exhaust gas introduced to the turbine wheel, thereby enhancing the supercharging effect.

[0003] To improve the performance of variable geometry turbines, it is effective to suppress leakage flow from the gaps on the nozzle vane end faces. To achieve this, the distance between the two plate-like components (nozzle mount, nozzle plate) that form the exhaust gas flow path using the nozzle support has traditionally been adjusted to minimize the gap on the vane end faces. Furthermore, to facilitate easier assembly of the variable nozzle mechanism into the housing, a method of integrating the variable nozzle mechanism is sometimes used, such as by fixing both ends of the nozzle support to the nozzle mount and nozzle plate by crimping, welding, or press-fitting. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-072401 Summary of the Invention [Problem to be solved by the invention]

[0005] When a variable geometry turbine is in operation, the variable nozzle mechanism can be thermally deformed when high-temperature exhaust gas flows into the exhaust gas flow path of the variable geometry turbine. Because the nozzle support used in the variable nozzle mechanism has high rigidity, if a thermal expansion difference occurs between the nozzle mount and the nozzle plate, large stress is generated in the support part of the nozzle support, which may damage the nozzle support. To prevent damage to the nozzle support, the diameter of the nozzle support must be increased.

[0006] In view of the above circumstances, at least one embodiment of the present disclosure has an object to provide a turbine and a turbocharger that can suppress damage caused by thermal deformation of members that form an exhaust gas flow path. [Means for solving the problem]

[0007] A turbine according to at least one embodiment of the present disclosure comprises: a first housing having a scroll flow passage; a turbine wheel provided on the inner circumferential side of the scroll flow passage; a first plate-shaped member including an annular first plate portion; a second plate-shaped member including an annular second plate portion disposed facing the first plate portion on a tip side of the first plate portion in the axial direction of the turbine wheel, the second plate portion forming a gas flow path from the scroll flow path toward the turbine wheel between the first plate portion and the second plate portion; at least one variable nozzle vane disposed in the gas flow path and rotatably supported by the first plate-shaped member or the second plate-shaped member; a second housing disposed closer to a rear end of the turbine wheel in the axial direction than the first plate-shaped member; a rear-end biasing member disposed between the second housing and the first plate-shaped member and configured to bias the first plate portion toward the gas flow path; and at least one support member provided in the gas flow path, one end of which is connected to one of the first plate portion or the second plate portion, and the other end of which abuts the other of the first plate portion or the second plate portion.

[0008] A turbocharger according to at least one embodiment of the present disclosure includes: the turbine; a centrifugal compressor configured to be driven by the turbine. [Effects of the Invention]

[0009] According to at least one embodiment of the present disclosure, a turbine and a turbocharger are provided that can suppress damage to members that form an exhaust gas flow path when they are thermally deformed. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram of an internal combustion engine system including a turbocharger according to an embodiment; [Figure 2] 1 is a schematic cross-sectional view of an embodiment of a turbine taken along an axis thereof; [Figure 3] FIG. 2 is a schematic diagram of a variable nozzle unit included in a turbine according to an embodiment. [Figure 4] 1 is a schematic cross-sectional view showing an example of a cross section along an axis line on one side of the axis line of a turbine according to a first embodiment. [Figure 5] 1 is a schematic cross-sectional view showing an example of a cross section along an axis line on one side of the axis line of a turbine according to a first embodiment. [Figure 6] 1 is a schematic cross-sectional view showing an example of a cross section along an axis line on one side of the axis line of a turbine according to a first embodiment. [Figure 7] 1 is a schematic cross-sectional view showing an example of a cross section along an axis line on one side of the axis line of a turbine according to a first embodiment. [Figure 8] 1 is a schematic cross-sectional view showing an example of a cross section along an axis line on one side of the axis line of a turbine according to a first embodiment. [Figure 9] 1 is a schematic cross-sectional view showing an example of a cross section along an axis line on one side of the axis line of a turbine according to a first embodiment. [Figure 10]FIG. 10 is a schematic cross-sectional view showing an example of a cross section along an axis line on one side of the axis line of a turbine according to a second embodiment. [Figure 11] FIG. 10 is a schematic cross-sectional view showing an example of a cross section along an axis line on one side of the axis line of a turbine according to a second embodiment. [Figure 12] FIG. 10 is a schematic cross-sectional view showing an example of a cross section along an axis line on one side of the axis line of a turbine according to a second embodiment. [Figure 13] FIG. 10 is a schematic cross-sectional view showing an example of a cross section along an axis line on one side of the axis line of a turbine according to a second embodiment. [Figure 14] FIG. 10 is a schematic cross-sectional view showing an example of a cross section along an axis line on one side of the axis line of a turbine according to a third embodiment. [Figure 15] FIG. 10 is a schematic cross-sectional view showing an example of a cross section along an axis line on one side of the axis line of a turbine according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, several embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present disclosure.

[0012] (Turbocharger) FIG. 1 is a schematic diagram of an internal combustion engine system 10 including a turbocharger 1 according to one embodiment. A turbine 2 according to the present disclosure can be mounted on, for example, a turbocharger (supercharger) 1 for automobiles, ships, or industrial applications (e.g., land-based power generation). In the following embodiments, a turbine 2 mounted on a turbocharger 1 will be described as an example, but the turbine 2 according to the present disclosure is not limited to being mounted on a turbocharger 1. Furthermore, the working fluid of the turbine 2 does not need to be limited to exhaust gas. In other words, the turbine 2 according to the present disclosure may be configured as a standalone turbine 2, or may be configured in combination with a mechanism or device other than a centrifugal compressor 12, as long as it is capable of converting working fluid energy into mechanical power (e.g., rotational force). Furthermore, the use of the turbine 2 does not need to be limited.

[0013] 1, a turbocharger 1 according to some embodiments is configured to compress a fluid (e.g., air) by being driven by the energy of exhaust gas discharged from an internal combustion engine (engine) 11. The turbocharger 1 includes a turbine 2 and a centrifugal compressor 12 configured to be driven by the turbine 2.

[0014] The centrifugal compressor 12 includes an impeller 13 and a compressor housing 14 configured to rotatably accommodate the impeller 13. The turbine 2 includes at least a turbine wheel 3, a first housing (turbine housing) 4, and a second housing (bearing housing) 5 configured to rotatably accommodate the turbine wheel 3 between the first housing 4 and the second housing 4.

[0015] 1, the turbocharger 1 further includes a rotating shaft 15 having a turbine wheel 3 connected to one end thereof and an impeller 13 connected to the other end thereof, and a bearing 16 configured to rotatably support the rotating shaft 15 between the turbine wheel 3 and the impeller 13. The second housing 5 is disposed between the first housing 4 and the compressor housing 14, and is connected to each of the first housing 4 and the compressor housing 14 via fastening members (not shown), such as bolts and nuts. The second housing 5 may be configured to accommodate the bearing 16.

[0016] The turbine 2 of the turbocharger 1 is configured to rotate a turbine wheel 3 using the energy of exhaust gas discharged from an internal combustion engine 11. The impeller 13 is coaxially connected to the turbine wheel 3 via a rotary shaft 15, and is therefore driven to rotate about an axis LA in conjunction with the rotation of the turbine wheel 3. The centrifugal compressor 12 of the turbocharger 1 is configured to drive the impeller 13 to rotate about an axis LA, thereby drawing air (intake air, gas) into a compressor housing 14, compressing the air, and sending the compressed air to the internal combustion engine 11.

[0017] The compressed air sent from the centrifugal compressor 12 to the internal combustion engine 11 is used for combustion in the internal combustion engine 11. Exhaust gas generated by combustion in the internal combustion engine 11 is sent from the internal combustion engine 11 to the turbine 2, causing the turbine wheel 3 to rotate.

[0018] (impeller) 1, the impeller 13 is connected to the other end of the rotary shaft 15 and is therefore rotatable integrally with the rotary shaft 15 around the axis of the impeller 13. The impeller 13 is configured to guide air introduced along the axial direction of the impeller 13 to the outside in the radial direction of the impeller 13. In the illustrated embodiment, the impeller 13 is an open-type impeller that does not include an annular member surrounding the outer periphery of the blades of the impeller 13.

[0019] (Compressor housing) A gas introduction passage 141 and a scroll passage 142 are formed inside the compressor housing 14. In other words, the compressor housing 14 has the gas introduction passage 141 and the scroll passage 142.

[0020] The gas introduction passage 141 is a passage for taking in air (gas) from outside the compressor housing 14 (centrifugal compressor 12) and guiding the taken-in air to the impeller 13. The gas introduction passage 141 is provided on one side of the impeller 13 in the axial direction of the impeller 13, and extends along the axial direction of the impeller 13. By driving the impeller 13 to rotate, air is taken in from outside the compressor housing 14 into the gas introduction passage 141, and the taken-in air flows through the gas introduction passage 141 toward the impeller 13 and is guided to the impeller 13.

[0021] The scroll passage 142 is provided on the outer periphery of the impeller 13 and is a spiral passage extending along the circumferential direction of the impeller 13. Air that passes through the impeller 13 and is compressed by the impeller 13 is guided to the scroll passage 142. The compressed air that has passed through the scroll passage 142 is guided to the internal combustion engine 11.

[0022] 2 is a schematic cross-sectional view taken along the axis LA of the turbine 2 according to one embodiment. Hereinafter, the direction in which the axis LA of the turbine wheel 3 extends will be referred to as the axial direction of the turbine wheel 3 (turbine 2), the direction perpendicular to the axis LA will be referred to as the radial direction of the turbine wheel 3 (turbine 2), and the circumferential direction around the axis LA will be referred to as the circumferential direction of the turbine wheel 3 (turbine 2). Hereinafter, the side of the turbine wheel 3 (turbine 2) where the first housing 4 is located relative to the second housing 5 in the axial direction (the right side in FIG. 2) will be defined as the leading end side, and the side where the second housing 5 is located relative to the first housing 4 (the side opposite to the leading end side, the left side in FIG. 2) will be defined as the rear end side.

[0023] (turbine wheel) As shown in Fig. 2, the turbine wheel 3 includes a hub 31 having a substantially truncated cone shape and a plurality of turbine blades 32 provided on the outer peripheral surface of the hub 31. The plurality of turbine blades 32 are arranged at intervals from one another in the circumferential direction about the axis LA. The hub 31 and the plurality of turbine blades 32 are provided so as to be rotatable integrally with the rotating shaft 15 around the axis LA. The turbine wheel 3 is configured to guide exhaust gas introduced from the outside in the radial direction of the turbine wheel 3 to the tip side of the turbine wheel 3 along the axial direction of the turbine wheel 3. In the illustrated embodiment, the turbine wheel 3 is an open-type impeller that does not include an annular member surrounding the outer periphery of the turbine blades 32.

[0024] (Scroll flow path, exhaust gas discharge flow path) A scroll passage 41 for guiding exhaust gas discharged from the internal combustion engine 11 to the turbine wheel 3 and an exhaust gas discharge passage 42 for discharging exhaust gas that has passed through the turbine wheel 3 to the outside of the first housing 4 (turbine 2) are formed inside the first housing 4. In other words, the first housing 4 has the scroll passage 41 and the exhaust gas discharge passage 42. The scroll passage 41 is provided on the outer periphery of the turbine wheel 3 and is a spiral passage that extends along the circumferential direction of the turbine wheel 3. The exhaust gas discharge passage 42 extends from the turbine wheel 3 toward the tip side along the axial direction of the turbine wheel 3.

[0025] By fastening the first housing 4 and the second housing 5 together, an internal space 43 is formed between the first housing 4 and the second housing 5, connecting the scroll passage 41 and the exhaust gas discharge passage 42. A turbine wheel 3 is housed in this internal space 43 so as to be rotatable relative to the first housing 4 and the second housing 5. The turbine wheel 3 is provided on the inner peripheral side of the scroll passage 41.

[0026] The exhaust gas discharged from the internal combustion engine 11 is guided to the turbine wheel 3 via the scroll passage 41, and rotates the turbine wheel 3. The exhaust gas that has rotated the turbine wheel 3 is discharged to the outside of the first housing 4 (turbine 2) via the exhaust gas discharge passage 42.

[0027] (Variable nozzle unit) Fig. 3 is a schematic diagram of a variable nozzle unit 6 included in a turbine 2 according to one embodiment. As shown in Fig. 2, the turbine 2 further includes a variable nozzle unit 6 housed on the outer circumferential side of the turbine wheel 3 in the internal space 43 described above. The variable nozzle unit 6 forms a gas flow path (exhaust gas flow path) 43A for guiding exhaust gas from the scroll flow path 41 to the turbine wheel 3, and also serves to adjust the flow of exhaust gas in the gas flow path 43A. The gas flow path 43A is part of the internal space 43. The gas flow path 43A is formed between the scroll flow path 41 and the turbine wheel 3 so as to surround the periphery (radial outside) of the turbine wheel 3.

[0028] 2 and 3, the variable nozzle unit 6 includes a first plate-shaped member (nozzle mount) 7, a second plate-shaped member (nozzle plate) 8, at least one variable nozzle vane 61 (plurality in the illustrated example), an annular member (drive ring) 62, and at least one link member (plurality in the illustrated example) (lever plate) 63. The variable nozzle unit 6 is configured to be mounted on the turbine 2 so as to be able to vary the flow path area of gas supplied to the turbine wheel 3.

[0029] (First plate-shaped member) The first plate-shaped member (nozzle mount) 7 includes an annular first plate portion 71 that extends along the circumferential direction of the turbine wheel 3 on the outer periphery of the turbine wheel 3. A first flow path surface 72 that faces the gas flow path 43A is formed at the leading end side in the axial direction of the first plate portion 71, and a first back surface 73 is formed at the trailing end side in the axial direction of the first plate portion 71, i.e., on the side opposite to the first flow path surface 72. In the illustrated embodiment, each of the first flow path surface 72 and the first back surface 73 is annular surface that extends along the circumferential direction of the turbine wheel 3.

[0030] (Second plate-shaped member) The second plate-shaped member (nozzle plate) 8 is disposed opposite the first plate portion 71 and includes an annular second plate portion 81 that forms, between the first plate portion and the second plate portion, a gas flow path 43A extending from the scroll flow path 41 toward the turbine wheel 3. The second plate portion 81 is disposed closer to the tip end of the first plate portion 71 in the axial direction and extends along the circumferential direction of the turbine wheel 3 on the outer periphery of the turbine wheel 3. A second flow path surface 82 facing the gas flow path 43A is formed on the rear end side of the second plate portion 81 in the axial direction, and a second back surface 83 is formed on the tip side of the second plate portion 81 in the axial direction, i.e., on the side opposite to the second flow path surface 82. In the illustrated embodiment, the second flow path surface 82 and the second back surface 83 each comprise an annular surface extending along the circumferential direction of the turbine wheel 3.

[0031] The gas flow path 43A is formed between the first flow path surface 72 and the second flow path surface 82. The first flow path surface 72 is located closer to the rear end in the axial direction than the second flow path surface 82 and faces the second flow path surface 82. The exhaust gas introduced into the turbine 2 passes through the scroll flow path 41 and then the gas flow path 43A, and is then led to the turbine wheel 3 to rotate the turbine wheel 3.

[0032] The second housing 5 has a rear-end facing surface 51 that faces the first rear surface 73 of the first plate portion 71, with the first space 43B sandwiched between them. The first space 43B is part of the internal space 43, and is formed on the opposite side of the first plate portion 71 from the gas flow path 43A.

[0033] (Variable nozzle vane) Each of the multiple variable nozzle vanes 61 is disposed in the gas flow path 43A and supported by a first plate portion 71 (first plate-shaped member 7) or a second plate portion 81 (second plate-shaped member 8) so as to be rotatable about its respective rotation axis RC. Each of the multiple variable nozzle vanes 61 includes a blade surface 64 facing the gas flow path 43A, a tip-side end face 65 formed at the leading end of the blade surface 64 in the axial direction, a hub-side end face 66 formed at the trailing end of the blade surface 64 in the axial direction, and a rotation shaft portion 67 extending from the hub-side end face 66 toward the trailing end in the axial direction along the rotation axis RC of the variable nozzle vane 61. The multiple variable nozzle vanes 61 are disposed at intervals in the circumferential direction of the turbine wheel 3.

[0034] (Annular member) The annular member (drive ring) 62 is disposed in the first space 43B, and is configured to rotate about an axis LB of the annular member 62 relative to the first plate-like member 7 by an external driving force.

[0035] (Drive mechanism, control device) 2, the turbine 2 further includes a drive mechanism (actuator) 68 configured to transmit a drive force to the annular member 62 to rotate the annular member 62 about its axis LB, and a control device (controller) 69 configured to control the rotation of the annular member 62 about the axis LB. The drive mechanism 68 includes an electric motor that generates the drive force, an air cylinder that transmits the drive force, and the like.

[0036] (Link member) 3, the variable nozzle unit 6 includes link members (lever plates) 63 in the same number as the variable nozzle vanes 61. Each of the multiple link members 63 is arranged in the first space 43B, has one end 631 connected to the annular member 62, and has the other end 632 connected to the variable nozzle vane 61, and is configured to change the blade angle of the variable nozzle vane 61 connected to the other end 632 in conjunction with the rotation of the annular member 62.

[0037] In the embodiment shown in FIG. 3 , one end 631 of each link member 63 includes a fitting portion 631A that fits into a fitting portion 621 formed in the annular member 62. The fitting portion 621 includes a groove 621A formed in the outer circumferential edge of the annular member 62, and the fitting portion 631A is housed inside the groove 621A and is adapted to fit loosely into the groove 621A. The first plate portion 71 has a plurality of through holes 74 that penetrate the first flow path surface 72 and the first back surface 73. The plurality of through holes 74 are arranged at intervals in the circumferential direction of the turbine wheel 3. The first plate portion 71 has the same number of through holes 74 as the variable nozzle vanes 61 and link members 63. The other end of each link member 63 is connected to the tip end portion (the end portion on the rear end side) of the rotary shaft portion 67 that passes through the through hole 74 of the variable nozzle vane 61 corresponding to the link member 63.

[0038] In the embodiment shown in FIG. 2, each of the multiple variable nozzle vanes 61 is rotatably supported on the first plate-shaped member 7, but in some other embodiments, each of the multiple variable nozzle vanes 61 may be rotatably supported on the second plate-shaped member 8.

[0039] When the annular member 62 is rotated to one side in the circumferential direction of the turbine wheel 3, the variable nozzle vanes 61 adjacent to each other in the circumferential direction move (rotate) in directions away from each other, increasing the flow path cross-sectional area of the gas flow path 43A between the variable nozzle vanes 61. When the annular member 62 is rotated to the other side in the circumferential direction of the turbine wheel 3, the variable nozzle vanes 61 adjacent to each other in the circumferential direction move (rotate) in directions approaching each other, decreasing the flow path cross-sectional area of the gas flow path 43A between the variable nozzle vanes 61.

[0040] The variable nozzle unit 6 rotates the variable nozzle vanes 61 about their respective rotation axes RC by transmitting a driving force from outside the variable nozzle unit 6 (drive mechanism 68) to the variable nozzle vanes 61 via an annular member 62 and multiple link members 63, thereby changing the blade angle of each. The turbine 2 can change the flow velocity and pressure of the exhaust gas guided to the turbine wheel 3 by increasing or decreasing the flow path cross-sectional area of the gas path 43A using the variable nozzle unit 6, thereby controlling the boost pressure of the turbine 2.

[0041] (First embodiment) 4 to 9 are schematic cross-sectional views showing an example of a cross section along the axis LA on one side of the axis LA of the turbine 2 (2A) according to the first embodiment. As shown in FIGS. 4 to 9, the turbine 2 (2A) according to some embodiments at least includes the turbine wheel 3 described above, the first housing 4 described above, the second housing 5 described above, the first plate-shaped member 7 described above including the annular first plate portion 71, the second plate-shaped member 8 described above including the annular second plate portion 81, and at least one variable nozzle vane 61 described above that is rotatably supported on the first plate-shaped member 7 or the second plate-shaped member 8.

[0042] 4 to 9, the gas flow path 43A is formed between the first flow path surface 72 and the second flow path surface 82. The tip side end surface 65 of each of the multiple variable nozzle vanes 61 faces the second flow path surface 82 via a gap, and the hub side end surface 66 faces the first flow path surface 72 via a gap.

[0043] As shown in Figures 4 to 9, the turbine 2 (2A) further includes a rear end biasing member (back plate) 21 that is arranged between the second housing 5 and the first plate-shaped member 7 and is configured to bias the first plate portion 71 of the first plate-shaped member 7 toward the gas flow path 43A, and at least one (e.g., multiple) support member 9 that is provided in the gas flow path 43A and has one end 91 connected to one plate portion 71A of the first plate portion 71 or the second plate portion 81 and the other end 92 abutting the other plate portion 81A of the first plate portion 71 or the second plate portion 81.

[0044] (Rear end biasing member) 4 to 9, the rear-end biasing member 21 includes a disc spring 21A that abuts against an end face 52 formed radially inward of the rear-end opposing surface 51 of the second housing 5, and an end face 75A of the inner peripheral edge portion 75 of the first plate portion 71 opposite the first flow path surface 72. The end face 75A is formed radially inward of the first back surface 73. The disc spring 21A (rear-end biasing member 21) seals the gap between the end face 52 of the second housing 5 and the end face 75A of the first plate portion 71, thereby suppressing the inflow of exhaust gas from the back side of the turbine wheel 3 into the first space 43B.

[0045] 4 to 9, the first housing 4 includes a radially extending portion 44 extending along the radial direction of the turbine wheel 3. The radially extending portion 44 has a rear scroll flow passage surface 441 extending radially outward from a rear end P1, which is the rear end of the scroll flow passage 41 in the axial direction. An outer peripheral edge portion 76 of the first plate portion 71 is located radially inward of the inner peripheral end of the radially extending portion 44 of the turbine wheel 3, and the first plate member 7 biased by the rear end biasing member 21 does not come into contact with the radially extending portion 44 even when moving along the axial direction of the turbine wheel 3.

[0046] (support member) Each of the multiple support members 9 is disposed in the gas flow path 43A upstream of the variable nozzle vane 61, i.e., outward of the variable nozzle vane 61 in the radial direction of the turbine wheel 3. Each of the multiple support members 9 supports the first plate-shaped member 7 and the second plate-shaped member 8 while keeping them spaced apart from each other, forming a first gap G1 between the first plate portion 71 and the second plate portion 81. The multiple support members 9 are disposed at intervals in the circumferential direction of the turbine wheel 3. Each of the multiple support members 9 is formed in a rod shape extending along the axial direction of the turbine wheel 3.

[0047] In the embodiment shown in FIGS. 4 and 6 to 9, the first plate portion 71 corresponds to one plate portion 71A, and the second plate portion 81 corresponds to the other plate portion 81A. That is, each of the plurality of support members 9 has one end 91, which is the end on the rear end side (one side) in the axial direction, connected to the first plate portion 71, and the other end 92, which is the end on the front end side (the other side) in the axial direction, abutting against the second plate portion 81. The one end 91 of the support member 9 may be inserted into a hole formed in the one plate portion 71A and fixed to the one plate portion 71A by caulking, welding, press-fitting, or the like. As shown in FIG. 4, the other end 92 of the support member 9 may have a flat end surface abutting against the second flow path surface 82 of the second plate portion 81.

[0048] In the embodiment shown in FIG. 5, the second plate portion 81 corresponds to one plate portion 71A, and the first plate portion 71 corresponds to the other plate portion 81A. That is, each of the plurality of support members 9 has one end 91, which is the end on the leading side (one side) in the axial direction, connected to the second plate portion 81, and the other end 92, which is the end on the rear side (the other side) in the axial direction, abutting against the first plate portion 71. The one end 91 of the support member 9 may be inserted into a hole formed in the one plate portion 71A and fixed to the one plate portion 71A by caulking, welding, press-fitting, or the like. As shown in FIG. 5, the other end 92 of the support member 9 may have a flat end surface abutting against the first flow path surface 72 of the first plate portion 71.

[0049] According to the above configuration, the rear end biasing member 21 presses the support member 9 against the other plate portion 81A, thereby generating a frictional force between the support member 9 and the other plate portion 81A. This frictional force can prevent the relative positional relationship between the support member 9 and the other plate portion 81A from being shifted. According to the above configuration, the support member 9 is not rigidly constrained in the radial direction relative to at least one of the first plate member 7 and the second plate member 8. This reduces stress generated in the support member 9 due to the difference in thermal expansion between the first plate member 7 and the second plate member 8 when the members (the first plate member 7, the second plate member 8, and the support member 9) that form the gas flow path 43A are thermally deformed during operation of the turbine 2. This reduces damage to the support member 9 when the members 7, 8, and 9 that form the gas flow path 43A are thermally deformed. Here, when the members 7, 8, and 9 forming the gas flow path 43A are thermally deformed, the second plate-shaped member 8, whose outer peripheral edge portion, etc. of the second plate portion 81 faces the scroll flow path 41, has a larger amount of thermal expansion than the first plate-shaped member 7.

[0050] According to the above configuration, by reducing the stress generated in the support member 9 when the members 7, 8, and 9 that form the gas flow path 43A are thermally deformed, the width dimension of the support member 9 can be made smaller, and the adverse effect that the support member 9 has on the flow entering the variable nozzle vane 61 can be reduced. In addition, it is no longer necessary to use a high-strength material that is expensive and difficult to obtain for the support member 9. For example, a relatively inexpensive and easily obtainable metal material such as steel may be used for the support member 9.

[0051] 4 and 6 to 9, at least one of the support members 9 has one end 91 connected to the first plate portion 71 and the other end 92 abutting against the second plate portion 81. In this case, connecting one end 91 of the support member 9 to the first plate portion 71 that is biased by the rear-end biasing member 21 and abutting the other end 92 of the support member 9 against the second plate portion 81 is preferable because it reduces the risk of misalignment between the support member 9 and the variable nozzle vane 61 compared to the case in which the other end 92 of the support member 9 abuts against the first plate portion 71 as shown in FIG. 5. This makes it easier to align the variable nozzle unit 6 when assembling it, thereby improving the ease of assembly of the variable nozzle unit 6.

[0052] (Annular contact part) 4 to 9 , the first housing 4 includes a tip-side opposing surface 45 that faces the second back surface 83 of the second plate portion 81 across a gap G2, and an annular abutment portion 46 that protrudes from the tip-side opposing surface 45 and abuts against the second back surface 83. The tip-side opposing surface 45 is located closer to the tip end in the axial direction than the second back surface 83, and the annular abutment portion 46 protrudes from the tip-side opposing surface 45 toward the rear end in the axial direction. The annular abutment portion 46 extends along the circumferential direction of the turbine wheel 3.

[0053] According to the above configuration, the gap G2 between the tip-side opposing surface 45 of the first housing 4 and the back surface 83 of the second plate portion 81 can be sealed by bringing the annular abutment portion 46 of the first housing 4 into contact with the back surface 83 of the second plate portion 81. In this case, there is no need to provide a separate sealing member for sealing the gap G2, and therefore the number of parts of the turbine 2 can be reduced.

[0054] 4 to 9 , the above-described annular abutment portion 46 has an annular abutment surface 46A that abuts against the second back surface 83 at least at a radial position through which the axis LD of the support member 9 passes. The annular abutment surface 46A is formed further outward in the radial direction of the turbine wheel 3 than the tip-side opposing surface 45 and the variable nozzle vane 61. Note that at least the outer peripheral end of the annular abutment portion 46 may face the scroll passage 41, and the annular abutment surface 46A may be continuous with the flow passage surface that forms the scroll passage 41.

[0055] According to the above configuration, the annular abutment portion 46 has the annular abutment surface 46A that functions as a sealing surface that seals the gap G2 between the second back surface 83 of the second plate portion 81, thereby ensuring the abutment area of the abutment surface between the annular abutment portion 46 and the second back surface 83, and thereby ensuring sealing performance. Furthermore, according to the above configuration, by aligning the radial position through which the axis LD of the support member 9 passes and the radial position where the annular abutment surface 46A is formed, it is possible to reduce bending stress occurring in the second plate portion 81 and deformation of the second plate portion 81 due to the bending stress.

[0056] If the radial position where the annular abutment surface 46A is formed is significantly deviated from the radial position through which the axis LD of the support member 9 passes, a large bending stress may be generated in the second plate portion 81 against which the support member 9 is pressed, which may deform the second plate portion 81. Furthermore, if the radial position where the annular abutment surface 46A is formed is deviated radially inward from the radial position through which the axis LD of the support member 9 passes, heat of the exhaust gas flowing through the scroll flow path 41 may be transferred from the second back surface 83 to the support member 9 via the second plate portion 81, causing the temperature of the support member 9 to rise, which may increase the risk of a decrease in strength or deformation of the support member 9.

[0057] (Shroud part of the first housing) In some embodiments, as shown in FIGS. 4 to 9, the first housing 4 includes a cylindrical shroud portion 47 that is inserted into the center hole 84 of the second plate portion 81 and covers the turbine wheel 3.

[0058] 4 to 9, the shroud portion 47 is located radially inward of the turbine wheel 3 with respect to the central hole 84 and the tip-side opposing surface 45 of the second plate portion 81, and protrudes toward the rear end in the axial direction beyond the tip-side opposing surface 45. The shroud portion 47 has a shroud surface 47A that is convexly curved to face the tip-side end faces (tips) of the multiple turbine blades 32, and has a gap (clearance) formed between the shroud portion 47 and the tip-side end faces of the turbine blades 32.

[0059] Taking into consideration thermal deformation of the first housing 4 and the second plate-shaped member 8 when the turbine 2 is in operation, it is preferable that a gap be formed between the center hole 84 of the second plate portion 81 and the outer peripheral surface of the shroud portion 47 when the turbine 2 is not in operation (when no thermal deformation occurs when the turbine 2 is in operation) in the first housing 4 or the second plate-shaped member 8, so that the shroud portion 47 is loosely inserted into the center hole 84 of the second plate portion 81. Note that when the turbine 2 is in operation, the center hole 84 of the second plate portion 81 and the outer peripheral surface of the shroud portion 47 may or may not come into contact with each other.

[0060] (Recess formed on the other plate) In some embodiments, as shown in FIG. 6, the other plate portion 81A described above has a recess 85A formed in the flow path surface 72, 82 facing the gas flow path 43A, and has a bottom surface 851 of the recess 85A against which the other end 92 of at least one support member 9 abuts.

[0061] The recess 85A may be an arc-shaped or annular groove extending along the circumferential direction of the turbine wheel 3, or may be a countersunk hole having a hole shape with a larger diameter than the other end 92 of the support member 9.

[0062] According to the above configuration, by abutting the other end 92 of the support member 9 against the bottom surface 851 of the recess 85A formed in the other plate portion 81A, movement of the support member 9 is restricted by the recess 85A, and therefore displacement of the other plate portion 81A in the radial direction of the turbine wheel 3 is suppressed. This makes it possible to suppress displacement in the radial direction between the other plate portion 81A and the other end 92 of the support member 9, and ultimately to suppress wear due to sliding between the other plate portion 81A and the other end 92 of the support member 9. Note that if the recess 85A is a countersunk hole, displacement of the other plate portion 81A in the circumferential direction of the turbine wheel 3 can also be suppressed. Furthermore, in the embodiment shown in Figure 6, the second plate portion 81 corresponds to the other plate portion 81A, and a recess 85A is formed in this second plate portion 81, but in the case where the first plate portion 71 corresponds to the other plate portion 81A, as shown in Figure 5, the recess 85A may also be formed in the first plate portion 71.

[0063] (Hole formed in the other plate) In some embodiments, as shown in FIG. 9, the other plate portion 81A described above has a hole portion 85B formed in the flow path surface 72, 82 (flow path surface 82 in the illustrated example) facing the gas flow path 43A, and the other end 92 of the at least one support member 9 described above includes a step surface 92A abutting the flow path surface 72, 82 (flow path surface 82 in the illustrated example) and an insertion portion 92B protruding beyond the step surface 92A and inserted into the hole portion 85B.

[0064] Step surface 92A extends more radially outward than insertion portion 92B, and its outer peripheral edge is formed to have a diameter larger than the inner diameter of hole 85B. In the embodiment shown in Fig. 9, hole 85B is a through-hole that penetrates the other plate portion 81A in its thickness direction (the axial direction), but hole 85B may be a bottomed hole, and the depth of the bottomed hole may be larger than the length of insertion portion 92B so that a gap is formed between the bottom of this bottomed hole and insertion portion 92B.

[0065] According to the above configuration, by inserting the insertion portion 92B of the support member 9 into the hole portion 85B formed in the other plate portion 81A and abutting the step surface 92A of the support member 9 against the flow path surfaces 72, 82 of the other plate portion 81A, it is possible to suppress misalignment between the other plate portion 81A and the other end 92 of the support member 9 in the radial and circumferential directions of the turbine wheel 3, and ultimately to suppress wear due to sliding between the other plate portion 81A and the other end 92 of the support member 9.

[0066] (Lightweight second plate-shaped member) 7 and 8, the other plate portion 81A (second plate portion 81 in the illustrated example) is held in place by a frictional force generated between the other end 92 of the support member 9 and the other plate portion 81A due to the biasing force of the rear end biasing member 21. Here, the force generated by vibrations in the second plate member 8 due to the action of engine vibrations and the like increases as the mass of the second plate member 8 increases.

[0067] In some embodiments, as shown in FIG. 7, the first housing 4 described above includes the shroud portion 47 described above, and the inner diameter D2 of the second plate portion 81 is larger than the inner diameter D1 of the first plate portion 71.

[0068] According to the above configuration, by making the inner diameter D2 of the second plate portion 81 larger than the inner diameter D1 of the first plate portion 71, the mass of the second plate member 8 can be reduced, thereby reducing the force generated by vibration on the second plate member 8. In this case, the support member 9 can be held even with a small holding force (frictional force) for holding the support member 9, and the support member 9 can be prevented from slipping relative to the other plate portion 81A. By reducing the holding force, the frictional force at the contact portion between the other plate portion 81A and the support member 9 and the contact portion between the annular contact portion 46 of the first housing 4 and the second plate portion 81 can be reduced, thereby reducing the risk of wear at these contact portions. Furthermore, the amount of material used for the second plate member 8 can be reduced. Note that if the other plate portion 81A (second plate portion 81) is held by the frictional force generated by the biasing force of the rear-end biasing member 21, there is a risk of the other plate portion 81A being displaced in the radial direction. Therefore, to reduce this risk, it is preferable to combine this embodiment with the embodiments shown in FIGS. 6 and 9.

[0069] 8, the first housing 4 includes the shroud portion 47, and the second plate portion 81 includes a thick portion 81B having a recess 85A or a hole 85B, and a thin portion 81C provided on the second plate portion 81 more inwardly than the thick portion 81B and having a smaller thickness in the axial direction of the turbine wheel 3 than the thick portion 81B. The thin portion 81C has a second back surface 83 located more rearward in the axial direction than the thick portion 81B.

[0070] According to the above configuration, by forming the thin-walled portion 81C, which is thinner than the thick-walled portion 81B, in the second plate portion 81, the mass of the second plate-shaped member 8 can be reduced, and the force generated by vibration in the second plate-shaped member 8 can be reduced. In this case, the support member 9 can be held even with a small holding force (friction force) for holding the support member 9, and the support member 9 can be prevented from slipping relative to the other plate portion 81A. By reducing the holding force, the friction force at the contact portion between the other plate portion 81A and the support member 9 and the contact portion between the annular contact portion 46 of the first housing 4 and the second plate portion 81 can be reduced, thereby reducing the risk of wear at these contact portions. In addition, the amount of material used in the second plate-shaped member 8 can be reduced.

[0071] (Second embodiment) 10 to 13 are schematic cross-sectional views showing an example of a cross section along the axis LA on one side of the axis LA of a turbine 2 (2B) according to a second embodiment. As shown in FIGS. 10 to 13, a turbine 2 (2B) according to some embodiments includes at least the turbine wheel 3 described above, the first housing 4 including the tip-side opposing surface 45, the second housing 5 described above, the first plate-shaped member 7 including the annular first plate portion 71, the second plate-shaped member 8 including the annular second plate portion 81, and at least one variable nozzle vane 61 rotatably supported by the first plate-shaped member 7 or the second plate-shaped member 8.

[0072] 10 to 13, the gas flow path 43A is formed between the first flow path surface 72 and the second flow path surface 82. The hub-side end surface 66 of each of the multiple variable nozzle vanes 61 faces the first flow path surface 72 with a gap therebetween.

[0073] As shown in FIGS. 10 to 13, the turbine 2 (2B) does not include a support member (for example, support member 9) that supports the above-described first plate-shaped member 7 and second plate-shaped member 8 in a spaced-apart state. The turbine 2 (2B) further includes a front-end biasing member 22 that is disposed between the second rear surface 83 of the second plate portion 81 and the tip-side opposing surface 45 that faces the second rear surface 83 of the first housing 4 across a gap G2. The front-end biasing member 22 is configured to bias the second plate portion 81 toward the gas flow path 43A.

[0074] In the embodiment shown in Figure 10, the front end side urging member 22 presses the second plate portion 81 against each of the multiple variable nozzle vanes 61, so that the second flow path surface 82 abuts against the tip side end face 65 of each of the multiple variable nozzle vanes 61.

[0075] According to the above configuration, the front-end biasing member 22 presses the second plate portion 81 against the variable nozzle vane 61, thereby minimizing the gap G2 between the second plate portion 81 and the variable nozzle vane 61. Furthermore, according to the above configuration, it is not necessary to provide a member (blocking member) such as the support member 9 that blocks a portion of the gas flow path 43A upstream of the variable nozzle vane 61, thereby improving the efficiency of the turbine 2. According to the above configuration, it is not necessary to provide a blockage member (support member 9), thereby suppressing unstable behavior of the variable nozzle vane 61 that occurs when the flow downstream of the blockage member in the gas flow path 43A is disturbed by the blockage member, thereby improving the reliability of the variable nozzle vane 61. Furthermore, according to the above configuration, it is not necessary to provide a blockage member (support member 9), thereby reducing the number of parts of the turbine 2.

[0076] (locked part) 10 to 13, the turbine 2 (2B) further includes a rear-end biasing member 21 that is disposed between the second housing 5 and the first plate member 7 and that is configured to bias the first plate portion 71 toward the gas flow path 43A. The first housing 4 extends in the radial direction of the turbine wheel 3 and includes an engaged portion (radially extending portion 44) to which an outer peripheral edge portion 76 of the first plate portion 71 that is biased by the rear-end biasing member 21 is engaged.

[0077] The locked portion 44 is located on the opposite side (rear end side) in the axial direction from the rear scroll flow path surface 441 and has a locked surface 442 facing the first space 43B. When the first plate-shaped member 7 is biased toward the tip side in the axial direction by the rear end biasing member 21, the outer peripheral edge portion 76 of the first plate portion 71 is pressed against the locked portion 44 of the first housing 4, and a locking surface 76A formed on the tip side of the outer peripheral edge portion 76 in the axial direction abuts against the locked surface 442. This seals the gap between the locking surface 76A and the locked surface 442, thereby suppressing the inflow of exhaust gas from the scroll flow path 41 into the first space 43B. Furthermore, when the outer peripheral edge portion 76 of the first plate portion 71 is pressed against the locked portion 44 of the first housing 4, movement of the first plate-shaped member 7 toward the tip side in the axial direction is limited. In the illustrated embodiment, the locking surface 76A is a stepped surface formed radially outward and rearward of the first flow path surface 72. Note that in some other embodiments, the outer peripheral edge portion 76 of the first plate portion 71 may be sandwiched between the first housing 4 and the second housing 5, thereby restricting movement of the first plate-shaped member 7 toward the tip side in the axial direction.

[0078] According to the above configuration, the first plate-shaped member 7 is biased by the rear-end biasing member 21, so that the outer peripheral edge 76 of the first plate portion 71 is pressed against the locked portion 44 of the first housing 4. In other words, the first plate-shaped member 7 is held in place by frictional force generated between the outer peripheral edge 76 of the first plate portion 71 and the locked portion 44 of the first housing 4 due to the biasing force of the rear-end biasing member 21. This makes it possible to prevent the first plate-shaped member 7 from being displaced relative to the first housing 4 and the second housing 5.

[0079] (Annular elastic sealing member) In some embodiments, the front end biasing member 22 described above includes annular elastic seal members 22A and 22B that abut against the second rear surface 83 and the front end opposing surface 45, respectively, as shown in FIGS.

[0080] 10, the front-end biasing member 22 includes a disc spring 22A that abuts against each of the second back surface 83 and the tip-side opposing surface 45. The disc spring 22A is formed in an annular shape that extends along the circumferential direction of the turbine wheel 3. The disc spring 22A (front-end biasing member 22) seals the gap between the second back surface 83 and the tip-side opposing surface 45, thereby suppressing the inflow of exhaust gas from the outside to the inside in the radial direction of the disc spring 22A.

[0081] According to the above configuration, the front end side biasing member 22 includes annular elastic sealing members 22A, 22B, and therefore can apply a pressing load toward the variable nozzle vane 61 to the second plate portion 81, and can seal the gap G2 between the second back surface 83 and the tip side opposing surface 45, thereby suppressing gas leakage through the gap G2.

[0082] In some embodiments, the above-mentioned annular sealing member 22B includes, as shown in Figures 11 and 12, a first urging plate portion 221 extending along the radial direction of the turbine wheel 3 and at least its outer peripheral end abutting the back surface 83 of the second plate portion 81, a second urging plate portion 222 extending along the radial direction of the turbine wheel 3 and at least its outer peripheral end abutting the tip-side opposing surface 45, and a connecting portion 223 connecting the inner peripheral end of the first urging plate portion 221 and the inner peripheral end of the second urging plate portion 222.

[0083] The cross section of the annular seal member 22B may be V-shaped (see FIG. 11), U-shaped (see FIG. 12), or W-shaped.

[0084] According to the above configuration, the annular elastic seal member 22B can apply a pressing load toward the variable nozzle vane 61 to the second plate portion 81 by abutting the first biasing plate portion 221 against the back surface 83 of the second plate portion 81 and the second biasing plate portion 222 against the tip-end opposed surface 45 of the first housing 4, and can also seal the gap G2 between the back surface 83 of the second plate portion 81 and the tip-end opposed surface 45 of the first housing 4. Furthermore, the annular elastic seal member 22B includes a connection portion 223 that connects the inner circumferential end of the first biasing plate portion 221 and the inner circumferential end of the second biasing plate portion 222, and therefore has an opening shape that opens outward in the radial direction of the turbine wheel 3. The annular elastic sealing member 22B having this opening shape is such that the first and second urging plate portions 221 and 222 are pushed apart in the axial direction of the turbine wheel 3 by the pressure of the gas flowing radially outward from the annular elastic sealing member 22B, thereby effectively sealing the gap G2 between the back surface 83 of the second plate portion 81 and the tip-side opposing surface 45 of the first housing 4.

[0085] (Protrusion on the tip end surface) 13, the at least one variable nozzle vane 61 includes a tip end face 65 that faces the second flow path face 82 of the second plate portion 81 via a gap, and a protrusion 651 that protrudes from the tip end face 65 and abuts against the second flow path face 82 at least at a radial position through which the rotation axis RC of the variable nozzle vane 61 passes. In the embodiment shown in FIG. 13, the protrusion 651 has a convex curved surface that is convex from the tip end face 65 toward the tip end in the axial direction.

[0086] According to the above configuration, by abutting the protrusion 651 of the variable nozzle vane 61 against the flow path surface 82 of the second plate portion 81 and aligning the radial position of the protrusion 651 with the radial position of the rotation axis RC of the variable nozzle vane 61, the rotation radius of the friction action position on the tip side of the variable nozzle vane 61 (the distance between the friction action point on the tip side of the variable nozzle vane 61 and the rotation axis RC) can be made small, thereby reducing the rotational driving force required to rotate the variable nozzle vane 61.

[0087] (Annular plate member) 13, the at least one variable nozzle vane 61 includes a hub-side end face 66 that faces the first flow path surface 72 of the first plate portion 71 via a gap, and a rotary shaft portion 67 that extends from the hub-side end face 66 along the rotation axis RC of the variable nozzle vane 61. The turbine 2 (2B) described above further includes an annular plate member (washer) 23 that is disposed between the first flow path surface 72 and the hub-side end face 66 of the first plate portion 71 and surrounds the rotary shaft portion 67. As shown in FIG. 13, the rotary shaft portion 67 may be loosely inserted through the annular plate member 23 and abut against the first flow path surface 72 and the hub-side end face 66, respectively.

[0088] According to the above configuration, by arranging the annular plate member 23 surrounding the rotating shaft portion 67 between the hub-side end face 66 of the variable nozzle vane 61 and the first flow path surface 72 of the first plate portion 71, it is possible to reduce the rotation radius of the friction action position on the hub side of the variable nozzle vane 61 (the distance between the friction action point on the hub side of the variable nozzle vane 61 and the rotation axis RC), thereby enabling smooth rotation of the variable nozzle vane 61. Furthermore, by arranging the annular plate member 23 surrounding the rotating shaft portion 67 between the hub-side end face 66 and the first flow path surface 72, it is possible to suppress runout of the rotating shaft portion 67, which also enables smooth rotation of the variable nozzle vane 61.

[0089] (Contact portion of front end biasing member) 11 and 12, the at least one variable nozzle vane 61 described above includes a hub-side end face 66 that faces the first flow path surface 72 of the first plate portion 71 via a gap, and a rotation shaft portion 67 that extends from the hub-side end face 66 along the rotation axis RC of the variable nozzle vane 61. The front-end biasing member 22 described above has an abutment portion 224 that abuts against the second back surface 83 of the second plate portion 81 at least at a radial position through which the rotation axis RC of the variable nozzle vane 61 passes. In the embodiment shown in FIGS. 11 and 12, the abutment portion 224 is formed on at least the outer circumferential end portion of the first biasing plate portion 221.

[0090] According to the above configuration, by aligning the radial position of the abutment portion 224 on which the biasing force of the front-end side biasing member 22 acts with the radial position of the rotation axis RC of the variable nozzle vane 61, it is possible to prevent the second plate portion 81 biased by the front-end side biasing member 22 from tilting relative to the variable nozzle vane 61 and hindering the rotational movement of the variable nozzle vane 61, thereby reducing malfunction of the variable nozzle vane 61.

[0091] (positioning part) In some embodiments, the turbine 2 (2B) described above further includes a positioning portion 24 provided on the inner peripheral side of the front-end biasing member 22 described above, as shown in Figures 11 and 12, to limit the radial position of the front-end biasing member 22.

[0092] 11 and 12, the positioning portion 24 is formed in an annular or arcuate shape extending along the circumferential direction of the turbine wheel 3, and is inserted into the center hole of the front-end biasing member 22. The positioning portion 24 may be provided on the outer circumferential side of the shroud portion 47 described above, so that the shroud portion 47 can be inserted therethrough.

[0093] The positioning portion 24 may be a protrusion that is formed integrally with the first housing 4 and protrudes from the tip-side opposing surface 45 on the inner circumferential side of the front-end biasing member 22 toward the rear end in the axial direction. Alternatively, the positioning portion 24 may be a protrusion that is formed integrally with the second plate-shaped member 8 and protrudes from the second back surface 83 on the inner circumferential side of the front-end biasing member 22 toward the tip end in the axial direction. Alternatively, the positioning portion 24 may be a separate body from each of the first housing 4 and the second plate-shaped member 8, and may be, for example, an annular body or an arc-shaped body that extends along the circumferential direction of the turbine wheel 3.

[0094] According to the above configuration, by limiting the radial position of the front-end side biasing member 22 with the positioning portion 24, the radial position at which the biasing force of the front-end side biasing member 22 acts can be easily aligned with the radial position through which the rotation axis RC of the variable nozzle vane 61 passes. Furthermore, by limiting the radial position of the front-end side biasing member 22 with the positioning portion 24, it is possible to prevent the radial position at which the biasing force of the front-end side biasing member 22 acts from shifting. By preventing the radial position at which the biasing force of the front-end side biasing member 22 acts from shifting, it is possible to prevent the second plate portion 81 from tilting with respect to the variable nozzle vane 61 and hindering the rotational movement of the variable nozzle vane 61, and thereby reduce malfunctions of the variable nozzle vane 61.

[0095] (Third embodiment) 14 and 15 are schematic cross-sectional views showing an example of a cross section along the axis LA on one side of the axis LA of a turbine 2 (2C) according to a third embodiment. As shown in Fig. 14 and 15, a turbine 2 (2C) according to some embodiments at least includes the turbine wheel 3 described above, the first housing 4 described above including the tip-side opposing surface 45, the second housing 5 described above, the first plate-shaped member 7 described above including the annular first plate portion 71, and the at least one variable nozzle vane 61 described above rotatably supported on the first plate-shaped member 7.

[0096] As shown in FIGS. 14 and 15 , the turbine 2 (2C) does not include a support member (e.g., support member 9) that supports the first plate-shaped member 7 and the second plate-shaped member 8 while keeping them spaced apart, nor does it include the second plate-shaped member 8. In the embodiment shown in FIGS. 14 and 15 , the annular first plate portion 71 is disposed opposite a tip-side opposing surface 45 formed in the first housing 4 at a radial position between the scroll passage 41 and the turbine wheel 3, and forms a gas passage 43C from the scroll passage 41 toward the turbine wheel 3 together with the tip-side opposing surface 45. Each of the multiple variable nozzle vanes 61 is disposed in the gas passage 43C, and a hub-side end face 66 faces the first passage surface 72 via a gap.

[0097] 14 and 15, the turbine 2 (2C) includes an annular elastic seal member 25 that abuts against the tip-side end face 65 and the leading-end-side opposing surface 45 of at least one (for example, a plurality) variable nozzle vane 61. The annular elastic seal member 25 is configured to bias the tip-side end face 65 toward the first plate portion 71 (the rear end side in the axial direction).

[0098] According to the above configuration, the annular elastic seal member 25 can seal the gap G3 between the tip end face 65 and the tip end facing surface 45 of the first housing 4 by abutting against both the tip end face 65 of the variable nozzle vane 61 and the tip end facing surface 45 of the first housing 4. Furthermore, according to the above configuration, the annular elastic seal member 25 is pressed against the variable nozzle vane 61, thereby generating a frictional force between the annular elastic seal member 25 and the variable nozzle vane 61. This frictional force can prevent the relative positional relationship between the annular elastic seal member 25 and the variable nozzle vane 61 from shifting.

[0099] According to the above configuration, it is not necessary to provide a member (closing member) that closes a portion of the gas flow path 43C on the upstream side of the variable nozzle vane 61, such as the support member 9 described above, thereby improving the efficiency of the turbine 2. According to the above configuration, it is not necessary to provide a closing member (support member 9), so it is possible to suppress unstable behavior of the variable nozzle vane 61 that occurs when the flow on the downstream side of the closing member in the gas flow path 43C is disturbed by the closing member, thereby improving the reliability of the variable nozzle vane 61. Furthermore, according to the above configuration, it is not necessary to provide the closing member (support member 9) and the second plate-shaped member 8, so it is possible to reduce the number of parts of the turbine 2.

[0100] (locked part) 14 and 15 , the turbine 2 (2C) further includes a rear-end biasing member 21 that is disposed between the second housing 5 and the first plate member 7 and configured to bias the first plate portion 71 toward the gas flow path 43C. The first housing 4 extends in the radial direction of the turbine wheel 3 and includes an engaged portion (radially extending portion 44) to which an outer peripheral edge portion 76 of the first plate portion 71 biased by the rear-end biasing member 21 is engaged.

[0101] The locked portion 44 is located on the opposite side (rear end side) in the axial direction from the rear scroll flow path surface 441 and has a locked surface 442 facing the first space 43B. When the first plate-shaped member 7 is biased toward the tip side in the axial direction by the rear end biasing member 21, the outer peripheral edge portion 76 of the first plate portion 71 is pressed against the locked portion 44 of the first housing 4, and a locking surface 76A formed on the tip side of the outer peripheral edge portion 76 in the axial direction abuts against the locked surface 442. This seals the gap between the locking surface 76A and the locked surface 442, thereby suppressing the inflow of exhaust gas from the scroll flow path 41 into the first space 43B. Furthermore, when the outer peripheral edge portion 76 of the first plate portion 71 is pressed against the locked portion 44 of the first housing 4, movement of the first plate-shaped member 7 toward the tip side in the axial direction is limited. In the illustrated embodiment, the locking surface 76A is a stepped surface formed radially outward and rearward of the first flow path surface 72. Note that in some other embodiments, the outer peripheral edge portion 76 of the first plate portion 71 may be sandwiched between the first housing 4 and the second housing 5, thereby restricting movement of the first plate-shaped member 7 toward the tip side in the axial direction.

[0102] According to the above configuration, the first plate-shaped member 7 is biased by the rear-end biasing member 21, so that the outer peripheral edge 76 of the first plate portion 71 is pressed against the locked portion 44 of the first housing 4. In other words, the first plate-shaped member 7 is held in place by frictional force generated between the outer peripheral edge 76 of the first plate portion 71 and the locked portion 44 of the first housing 4 due to the biasing force of the rear-end biasing member 21. This makes it possible to prevent the first plate-shaped member 7 from being displaced relative to the first housing 4 and the second housing 5.

[0103] (Annular elastic sealing member) In some embodiments, the above-mentioned annular elastic sealing member 25 includes, as shown in Figures 14 and 15, a first urging plate portion 251 extending along the radial direction of the turbine wheel 3 and at least its outer peripheral end abutting against the tip side end face 65 of at least one variable nozzle vane 61, a second urging plate portion 252 extending along the radial direction of the turbine wheel 3 and at least its outer peripheral end abutting against the tip side opposing surface 45, and a connecting portion 253 connecting the inner peripheral end of the first urging plate portion 221 and the inner peripheral end of the second urging plate portion 252.

[0104] The cross section of the annular seal member 25 may be V-shaped (see FIG. 14), U-shaped (see FIG. 15), or W-shaped.

[0105] According to the above configuration, the annular elastic seal member 25 can apply a pressing load to the variable nozzle vane 61 and seal the gap G3 between the tip end face 65 and the tip end facing surface 45 of the first housing 4 by bringing the first urging plate portion 251 into contact with the tip end face 65 of the variable nozzle vane 61 and the second urging plate portion 252 into contact with the tip end facing surface 45 of the first housing 4. In addition, the annular elastic seal member 25 includes a connection portion 253 that connects the inner circumferential end of the first urging plate portion 251 and the inner circumferential end of the second urging plate portion 252, and therefore has an opening shape that opens outward in the radial direction of the turbine wheel 3. The annular elastic sealing member 25 having this opening shape can effectively seal the gap G3 between the tip side end face 65 and the tip side opposing face 45 because the first biasing plate portion 251 and the second biasing plate portion 252 are pushed apart in the axial direction of the turbine wheel 3 by the pressure of the gas flowing radially outside the annular elastic sealing member 25.

[0106] (Contact portion of front end biasing member) 14 and 15 , the at least one variable nozzle vane 61 described above includes a tip-side end face 65 opposing the tip-side opposing surface 45, a hub-side end face 66 opposing, via a gap, the first flow path surface 72 of the first plate portion 71 facing the gas flow path 43C, and a rotation shaft portion 67 extending from the hub-side end face 66 along the rotation axis RC of the variable nozzle vane 61. The annular elastic seal member 25 described above has an abutment portion 254 abutting against the tip-side end face 65 at least at a radial position through which the rotation axis RC of the variable nozzle vane 61 passes. In the embodiment shown in FIGS. 14 and 15 , the abutment portion 254 is formed on at least the outer circumferential end portion of the first biasing plate portion 251.

[0107] According to the above configuration, by aligning the radial position of the abutment portion 254, on which the biasing force of the annular elastic seal member 25 acts, with the radial position of the rotation axis RC of the variable nozzle vane 61, it is possible to effectively seal the gap G3 between the tip-side end face 65 and the leading-end opposing surface 45. In particular, gas leakage from the gap G3 can be effectively suppressed when the variable nozzle vane 61 is closed, which has a significant impact on performance degradation of the turbine 2 due to gas leakage from the gap G3, and performance degradation of the turbine 2 can be suppressed.

[0108] (positioning part) In some embodiments, the turbine 2 (2C) described above further includes a positioning portion 26 provided on the inner peripheral side of the annular elastic sealing member 25 described above, as shown in Figures 14 and 15, to limit the radial position of the annular elastic sealing member 25.

[0109] 14 and 15, the positioning portion 26 is formed in an annular or arcuate shape extending along the circumferential direction of the turbine wheel 3, and is inserted into the central hole of the annular elastic seal member 25. The positioning portion 26 may be provided on the outer circumferential side of the shroud portion 47 described above, so that the shroud portion 47 can be inserted therethrough.

[0110] The positioning portion 26 may be a protrusion formed integrally with the first housing 4 and protruding from the tip-side opposing surface 45 toward the rear end in the axial direction on the inner circumferential side of the annular elastic seal member 25. The positioning portion 26 may also be a separate body from the first housing 4, and may be, for example, an annular body or an arc-shaped body extending along the circumferential direction of the turbine wheel 3.

[0111] According to the above configuration, by limiting the radial position of the annular elastic seal member 25 with the positioning portion 26, the radial position at which the biasing force of the annular elastic seal member 25 acts can be easily aligned with the radial position through which the rotation axis RC of the variable nozzle vane 61 passes. Furthermore, by limiting the radial position of the annular elastic seal member 25 with the positioning portion 26, it is possible to prevent deviation of the radial position at which the biasing force of the annular elastic seal member 25 acts. By preventing deviation of the radial position at which the biasing force of the annular elastic seal member 25 acts, it is possible to effectively prevent gas leakage from the gap G3 between the tip-side end face 65 and the tip-side opposing surface 45, and to prevent a decrease in performance of the turbine 2.

[0112] 1, a turbocharger 1 according to some embodiments includes the above-described turbine 2 (2A to 2C) and the above-described centrifugal compressor 12 configured to be driven by the turbine 2. In this case, damage to the members forming the gas flow path 43A of the turbine 2 during thermal deformation can be suppressed, thereby improving the reliability of the turbocharger 1 equipped with the turbine 2.

[0113] In this specification, expressions expressing relative or absolute arrangement such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" not only express such an arrangement strictly, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained. For example, expressions such as "identical," "equal," and "homogeneous" that indicate that something is in an equal state not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained. Furthermore, in this specification, expressions representing shapes such as a rectangular shape or a cylindrical shape not only represent rectangular shapes or cylindrical shapes in the strict geometric sense, but also represent shapes including uneven portions, chamfered portions, etc., to the extent that the same effect can be obtained. Furthermore, in this specification, the expressions "comprise," "include," or "have" a component are not exclusive expressions that exclude the presence of other components.

[0114] The present disclosure is not limited to the above-described embodiments, but also includes modifications to the above-described embodiments and appropriate combinations of these modifications.

[0115] The contents of the above-described embodiments can be understood, for example, as follows.

[0116] 1) A turbine (2) according to at least one embodiment of the present disclosure comprises: a first housing (4) having a scroll flow passage (41); a turbine wheel (3) provided on the inner circumferential side of the scroll flow passage (41); a first plate-shaped member (7) including an annular first plate portion (71); a second plate-shaped member (8) including an annular second plate portion (81) disposed closer to a tip end of the first plate portion (71) in the axial direction of the turbine wheel (3) than the first plate portion (71) so as to face the first plate portion (71) and forming a gas flow path (43A) from the scroll flow path (41) to the turbine wheel (3) between the first plate portion (71) and the second plate-shaped member (8); at least one variable nozzle vane (61) disposed in the gas flow path (43A) and rotatably supported by the first plate-shaped member (7) or the second plate-shaped member (8); a second housing (5) disposed closer to the rear end of the turbine wheel (3) in the axial direction than the first plate-shaped member (7); a rear-end biasing member (21) disposed between the second housing (5) and the first plate-shaped member (7) and configured to bias the first plate portion (71) toward the gas flow path (43A); and at least one support member (9) that is provided in the gas flow path (43A), has one end (91) connected to one of the plate portions (71A) of the first plate portion (71) or the second plate portion (81), and has the other end (92) abutting against the other plate portion (81A) of the first plate portion (71) or the second plate portion (81).

[0117] According to the configuration 1), the rear-end biasing member 21 presses the support member 9 against the other plate portion 81A, thereby generating a frictional force between the support member 9 and the other plate portion 81A. This frictional force can prevent the relative positional relationship between the support member 9 and the other plate portion 81A from being displaced. According to the configuration 1), the support member 9 is not rigidly constrained in the radial direction by at least one of the first plate-shaped member 7 and the second plate-shaped member 8. This reduces stress generated in the support member 9 due to a difference in thermal expansion between the first plate-shaped member 7 and the second plate-shaped member 8 when the members (the first plate-shaped member 7, the second plate-shaped member 8, and the support member 9) forming the gas flow path 43A are thermally deformed during operation of the turbine 2. This reduces damage to the support member 9 when the members (7, 8, 9) forming the exhaust gas flow path are thermally deformed.

[0118] According to the above configuration 1), stress generated in the support member (9) when the members (7, 8, 9) forming the exhaust gas flow path (43A) are thermally deformed is reduced, thereby making it possible to reduce the width dimension of the support member (9) and reduce adverse effects of the support member (9) on the flow into the variable nozzle vane (61). In addition, it is not necessary to use a high-strength material that is expensive and difficult to obtain for the support member (9).

[0119] 2) In some embodiments, the turbine (2) according to 1) above, The first housing (4) includes: a front end opposing surface (45) facing a back surface (83) of the second plate portion (81) opposite to a flow path surface (82) facing the gas flow path (43A) with a gap (G2) therebetween; and an annular abutment portion (46) that protrudes from the tip-side opposing surface (45) and abuts against the back surface (83) of the second plate portion (81).

[0120] According to the configuration 2), the annular contact portion 46 of the first housing 4 is brought into contact with the back surface 83 of the second plate portion 81, thereby sealing the gap G2 between the tip-side opposing surface 45 of the first housing 4 and the back surface 83 of the second plate portion 81. In this case, there is no need to provide a separate sealing member for sealing the gap G2, and therefore the number of parts of the turbine 2 can be reduced.

[0121] 3) In some embodiments, the turbine (2) according to 2) above, The annular contact portion (46) has an annular contact surface (46A) that contacts the back surface (83) of the second plate portion (81) at least at a radial position through which the axis (LD) of the support member (9) passes.

[0122] According to the configuration of 3), the annular contact portion (46) has an annular contact surface (46A) that functions as a sealing surface that seals the gap (G2) between the annular contact portion (46) and the back surface (83) of the second plate portion (81), thereby ensuring a sufficient contact area at the contact surface between the annular contact portion (46) and the back surface (83) of the second plate portion (81), thereby ensuring sealing performance. Furthermore, according to the configuration of 3), the radial position through which the axis (LD) of the support member (9) passes is aligned with the radial position at which the annular contact surface (46A) is formed, thereby reducing bending stress generated in the second plate portion (81) and deformation of the second plate portion (81) due to the bending stress.

[0123] 4) In some embodiments, the turbine (2) according to any one of 1) to 3) above, The first housing (4) includes: The turbine wheel (3) includes a cylindrical shroud (47) that is inserted into a central hole (84) of the second plate (81) and covers the turbine wheel (3).

[0124] According to the configuration 4), the shroud portion (47) of the first housing (4) is inserted into the center hole (84) of the second plate portion (81), thereby suppressing misalignment of the second plate portion (81) in the radial direction of the turbine wheel (3). This makes it possible to suppress misalignment between the other plate portion (81A) and the other end (92) of the support member (9) in the radial direction, thereby suppressing wear due to sliding between the other plate portion (81A) and the other end (92) of the support member (9).

[0125] 5) In some embodiments, the turbine (2) according to any one of 1) to 4) above, The other plate portion (81A) has a recess (85A) formed in a flow path surface (72, 82) facing the gas flow path (43A), and the recess (85A) has a bottom surface (851) against which the other end (92) of the at least one support member (9) abuts.

[0126] According to the configuration 5), the other end (92) of the support member (9) is brought into contact with the bottom surface (851) of the recess (85A) formed in the other plate portion (81A), thereby suppressing misalignment of the other plate portion (81A) in the radial direction of the turbine wheel (3). This makes it possible to suppress misalignment between the other plate portion (81A) and the other end (92) of the support member (9) in the radial direction, thereby suppressing wear due to sliding between the other plate portion (81A) and the other end (92) of the support member (9).

[0127] 6) In some embodiments, the turbine (2) according to 5) above, The first housing (4) includes: a cylindrical shroud portion (47) that is inserted into a center hole (84) of the second plate portion (81) and covers the turbine wheel (3); The second plate portion (81) has an inner diameter larger than that of the first plate portion (71).

[0128] According to the configuration of 6) above, the support member (9) is held by frictional force generated between the other end (92) of the support member (9) and the other plate portion (81A) due to the biasing force of the rear end biasing member (21). Here, the force generated in the second plate member (8) due to vibration caused by engine vibration or the like increases as the mass of the second plate member (8) increases. By making the inner diameter (D2) of the second plate portion (81) larger than the inner diameter (D1) of the first plate portion (71), the mass of the second plate member (8) can be reduced, and the force generated in the second plate member (8) due to vibration can be reduced. In this case, the support member (9) can be held even if the holding force (frictional force) for holding the support member (9) is small, and slippage of the support member (9) relative to the other plate portion (81A) can be suppressed. By reducing the holding force, it is possible to reduce the frictional forces at the contact portion between the other plate portion (81A) and the support member (9) and at the contact portion between the annular contact portion (46) of the first housing (4) and the second plate portion (81), thereby reducing the risk of wear at these contact portions. Also, it is possible to reduce the amount of material used for the second plate member (8).

[0129] 7) In some embodiments, the turbine (2) according to 5) above, The first housing (4) includes: a cylindrical shroud portion (47) that is inserted into a center hole (84) of the second plate portion (81) and covers the turbine wheel (3); The second plate portion (81) a thick portion (81B) having the recess (85A); The second plate portion (81) includes a thin portion (81C) that is provided on the inner side of the thick portion (81B) of the second plate portion (81), and that is thinner in the axial direction of the turbine wheel (3) than the thick portion (81B).

[0130] According to the configuration of 7) above, the support member 9 is held by frictional force generated between the other end 92 of the support member 9 and the other plate portion 81A due to the biasing force of the rear end biasing member 21. Here, the force generated in the second plate member 8 due to vibration caused by engine vibration or the like increases as the mass of the second plate member 8 increases. By forming the thin-walled portion 81C, which is thinner than the thick-walled portion 81B, in the second plate portion 81, the mass of the second plate member 8 can be reduced, and the force generated in the second plate member 8 due to vibration can be reduced. In this case, the support member 9 can be held even if the holding force (frictional force) for holding the support member 9 is small, and slippage of the support member 9 relative to the other plate portion 81A can be suppressed. By reducing the holding force, it is possible to reduce the frictional forces at the contact portion between the other plate portion (81A) and the support member (9) and at the contact portion between the annular contact portion (46) of the first housing (4) and the second plate portion (81), thereby reducing the risk of wear at these contact portions. Also, it is possible to reduce the amount of material used for the second plate member (8).

[0131] 8) In some embodiments, the turbine (2) according to any one of 1) to 7) above, the other plate portion (81A) has a hole (85B) formed in a flow path surface (72, 82) facing the gas flow path (43A), The other end (92) of the at least one support member (9) a step surface (92A) that contacts the flow path surface (72, 82); and an insertion portion (92B) that protrudes beyond the step surface (92A) and is inserted into the hole (85B).

[0132] According to the configuration of 8), by inserting the insertion portion (92B) of the support member (9) into the hole portion (85B) formed in the other plate portion (81A) and abutting the step surface (92A) of the support member (9) against the flow path surface (72, 82) of the other plate portion (81A), it is possible to suppress misalignment between the other plate portion (81A) and the other end (92) of the support member (9) in the radial and circumferential directions of the turbine wheel (3), and thus it is possible to suppress wear due to sliding between the other plate portion (81A) and the other end (92) of the support member (9).

[0133] 9) In some embodiments, the turbine (2) according to any one of 1) to 8) above, The at least one support member (9) has one end (91) connected to the first plate portion (71) and the other end (92) abutting against the second plate portion (81).

[0134] According to the configuration 9), one end (91) of the support member (9) is connected to the first plate portion (71) that is biased by the rear end biasing member (21), and the other end (92) of the support member (9) is abutted against the second plate portion (81). This reduces the risk of misalignment between the support member (9) and the variable nozzle vane (61) compared to the case where the other end (92) of the support member (9) is abutted against the first plate portion (71), which is preferable. This makes it easier to align the variable nozzle unit (6) when assembling it, thereby improving the ease of assembly of the variable nozzle unit (6).

[0135] 10) The turbine (2) according to at least one embodiment of the present disclosure comprises: a first housing (4) having a scroll flow passage (41); a turbine wheel (3) provided on the inner circumferential side of the scroll flow passage (41); a first plate-shaped member (7) including an annular first plate portion (71); a second plate-shaped member (8) including an annular second plate portion (81) disposed closer to a tip end of the first plate portion (71) in the axial direction of the turbine wheel (3) than the first plate portion (71) so as to face the first plate portion (71) and forming a gas flow path (43A) from the scroll flow path (41) to the turbine wheel (3) between the first plate portion (71) and the second plate-shaped member (8); at least one variable nozzle vane (61) disposed in the gas flow path (43A) and rotatably supported by the first plate-shaped member (7) or the second plate-shaped member (8); a second housing (5) disposed closer to the rear end of the turbine wheel (3) in the axial direction than the first plate-shaped member (7); and a front-end biasing member (22) arranged between a back surface (83) of the second plate portion (81) opposite to a flow path surface (82) facing the gas flow path (43A) and a tip-side opposing surface (45) of the first housing (4) opposing the back surface (83) of the second plate portion (81) across a gap (G2), the front-end biasing member (22) being configured to bias the second plate portion (81) toward the gas flow path (43A).

[0136] According to the configuration of 10), the second plate portion (81) is pressed against the variable nozzle vane (61) by the front-end biasing member (22), thereby minimizing the gap (G2) between the second plate portion (81) and the variable nozzle vane (61). Furthermore, according to the configuration of 10), a member (obstruction member), such as the support member (9), that blocks a portion of the gas flow path (43A) on the upstream side of the variable nozzle vane (61) is not required, thereby improving the efficiency of the turbine (2). According to the configuration of 10), the obstruction member (support member 9) is not required, thereby suppressing unstable behavior of the variable nozzle vane (61) that occurs when the flow on the downstream side of the obstruction member in the gas flow path (43A) is disturbed by the obstruction member. This improves the reliability of the variable nozzle vane (61). Furthermore, according to the configuration of 10), the obstruction member (support member) is not required, thereby reducing the number of parts of the turbine (2).

[0137] 11) In some embodiments, the turbine (2) according to 10) above, a rear-end biasing member (21) disposed between the second housing (5) and the first plate-shaped member (7) and configured to bias the first plate portion (71) toward the gas flow path (43A), The first housing (4) extends radially of the turbine wheel (3) and includes an engaging portion (44) to which the outer peripheral edge portion (76) of the first plate portion (71) urged by the rear end side urging member (21) is engaged.

[0138] According to the configuration of 11), the first plate-shaped member 7 is biased by the rear-end biasing member 21, so that the outer peripheral edge 76 of the first plate portion 71 is pressed against the locked portion 44 of the first housing 4. That is, the first plate-shaped member 7 is held in place by frictional force generated between the outer peripheral edge 76 of the first plate portion 71 and the locked portion 44 of the first housing 4 due to the biasing force of the rear-end biasing member 21. This makes it possible to prevent the first plate-shaped member 7 from being displaced relative to the first housing 4 and the second housing 5.

[0139] 12) In some embodiments, the turbine (2) according to 10) or 11) above, The front-end biasing member (22) includes annular elastic seal members (22A, 22B) that come into contact with the back surface (83) and the tip-end opposing surface (45) of the second plate portion (81), respectively.

[0140] According to the configuration of 12), the front-end biasing member (22) includes the annular elastic sealing members (22A, 22B). Therefore, a pressing load toward the variable nozzle vane (61) can be applied to the second plate portion (81), and the gap (G2) between the back surface (83) of the second plate portion (81) and the tip-side opposing surface (45) of the first housing (4) can be sealed, thereby suppressing gas leakage through the gap (G2).

[0141] 13) In some embodiments, the turbine (2) according to 12) above, The annular elastic seal member (22B) is a first biasing plate portion (221) extending along the radial direction of the turbine wheel (3) and having at least an outer peripheral end portion abutting against the back surface (83) of the second plate portion (81); a second biasing plate portion (222) extending along the radial direction and having at least an outer peripheral end portion abutting against the tip-side opposing surface (45); and a connecting portion (223) that connects an inner peripheral end of the first urging plate portion (221) and an inner peripheral end of the second urging plate portion (222).

[0142] According to the configuration 13), the annular elastic seal member (22B) can apply a pressing load toward the variable nozzle vane (61) to the second plate portion (81) by bringing the first biasing plate portion (221) into contact with the back surface (83) of the second plate portion (81) and the second biasing plate portion (222) into contact with the front-end opposing surface (45) of the first housing (4). Furthermore, the annular elastic seal member (22B) can seal the gap (G2) between the back surface (83) of the second plate portion (81) and the front-end opposing surface (45) of the first housing (4). Furthermore, the annular elastic seal member (22B) includes a connecting portion (223) that connects an inner peripheral end of the first biasing plate portion (221) and an inner peripheral end of the second biasing plate portion (222), and therefore has an opening shape that opens outward in the radial direction of the turbine wheel (3). The annular elastic sealing member (22B) having this opening shape is such that the first biasing plate portion (221) and the second biasing plate portion (222) are pushed apart in the axial direction of the turbine wheel (3) by the pressure of the gas flowing radially outward from the annular elastic sealing member (22B), thereby effectively sealing the gap (G2) between the back surface (83) of the second plate portion (81) and the tip-side opposing surface (45) of the first housing (4).

[0143] 14) In some embodiments, the turbine (2) according to any one of 10) to 13) above, The at least one variable nozzle vane (61) a tip-side end surface (65) facing the flow path surface (82) of the second plate portion (81) via a gap; and a protrusion (651) that protrudes from the tip side end face (65) at least at a radial position through which the rotation axis (RC) of the variable nozzle vane (61) passes and abuts against the flow path surface (82) of the second plate portion (81).

[0144] According to the configuration 14) above, the protrusion (651) of the variable nozzle vane (65) is abutted against the flow path surface (82) of the second plate portion (81) and the radial position of the protrusion (651) is aligned with the radial position of the rotation axis (RC) of the variable nozzle vane (61), thereby making it possible to reduce the rotation radius of the friction action position on the tip side of the variable nozzle vane (61), and thereby reducing the rotational driving force required to rotate the variable nozzle vane (61).

[0145] 15) In some embodiments, the turbine (2) according to any one of 10) to 14) above, The at least one variable nozzle vane (61) a hub-side end surface (66) facing, via a gap, the flow path surface (72) of the first plate portion (71) facing the gas flow path (43A); a rotation shaft portion (67) extending from the hub-side end surface (66) along the rotation axis (RC) of the variable nozzle vane (61), The turbine (2) The compressor further includes an annular plate member (23) that is disposed between the flow path surface (72) of the first plate portion (71) and the hub-side end face (66) and surrounds the rotary shaft portion (67).

[0146] According to the configuration of 15), by disposing the annular plate member (23) surrounding the rotating shaft portion (67) between the hub-side end face (66) of the variable nozzle vane (61) and the flow path surface (72) of the first plate portion (71), it is possible to reduce the rotation radius of the friction acting position on the hub side of the variable nozzle vane (61), thereby enabling smooth rotation of the variable nozzle vane (61). In addition, by disposing the annular plate member (23) surrounding the rotating shaft portion (67) between the hub-side end face (66) of the variable nozzle vane (61) and the flow path surface (72) of the first plate portion (71), it is possible to suppress vibration of the rotating shaft portion (67), which also enables smooth rotation of the variable nozzle vane (61).

[0147] 16) In some embodiments, the turbine (2) according to any one of 10) to 15) above, The at least one variable nozzle vane (61) a hub-side end surface (66) facing, via a gap, the flow path surface (72) of the first plate portion (71) facing the gas flow path (43A); a rotation shaft portion (67) extending from the hub-side end surface (66) along the rotation axis (RC) of the variable nozzle vane (61), The front end biasing member (22) has an abutment portion (224) that abuts against the back surface (83) of the second plate portion (81) at least at a radial position through which the rotation axis (RC) of the variable nozzle vane (61) passes.

[0148] According to the configuration 16) above, by aligning the radial position of the abutment portion (224) on which the biasing force of the front-end biasing member (22) acts with the radial position of the rotation axis (RC) of the variable nozzle vane (61), it is possible to prevent the second plate portion (81) biased by the front-end biasing member (22) from tilting relative to the variable nozzle vane (61) and hindering the rotational movement of the variable nozzle vane (61), thereby reducing malfunction of the variable nozzle vane (61).

[0149] 17) In some embodiments, the turbine (2) according to 16) above, The front end biasing member (22) further includes a positioning portion (24) provided on the inner peripheral side of the front end biasing member (22) to limit the radial position of the front end biasing member (22).

[0150] According to the configuration of 17), the positioning portion (24) limits the radial position of the front-end biasing member (22), thereby easily aligning the radial position at which the biasing force of the front-end biasing member (22) acts with the radial position through which the rotation axis (RC) of the variable nozzle vane (61) passes. Furthermore, the positioning portion (24) limits the radial position of the front-end biasing member (22), thereby preventing the radial position at which the biasing force of the front-end biasing member (22) acts from shifting. Preventing the radial position at which the biasing force of the front-end biasing member (22) acts from shifting prevents the second plate portion (81) from tilting with respect to the variable nozzle vane (61) and inhibiting the rotation of the variable nozzle vane (61), thereby reducing malfunctions of the variable nozzle vane (61).

[0151] 18) The turbine (2) according to at least one embodiment of the present disclosure comprises: a first housing (4) having a scroll flow passage (41); a turbine wheel (3) provided on the inner circumferential side of the scroll flow passage (41); a first plate-like member (7) including an annular first plate portion (71) disposed opposite a tip-side opposing surface (45) formed in the first housing (4) at a radial position between the scroll passage (41) and the turbine wheel (3) and forming, together with the tip-side opposing surface (45), a gas passage (43C) extending from the scroll passage (41) to the turbine wheel (3); at least one variable nozzle vane (61) disposed in the gas flow path (43C) and rotatably supported by the first plate-shaped member (7); a second housing (5) disposed closer to the rear end of the turbine wheel (3) in the axial direction than the first plate-shaped member (7); and an annular elastic seal member (25) that abuts against the tip-side end face (65) of the at least one variable nozzle vane (61) and the leading-end-side opposing surface (45).

[0152] According to the configuration of 18), the annular elastic seal member (25) abuts against the tip end surface (65) of the variable nozzle vane (61) and the tip opposing surface (45) of the first housing (4), thereby sealing the gap (G3) between the tip end surface (65) and the tip opposing surface (45). Furthermore, according to the configuration of 18), the annular elastic seal member (25) is pressed against the variable nozzle vane (61), thereby generating a frictional force between the annular elastic seal member (25) and the variable nozzle vane (61). This frictional force can prevent a deviation in the relative positional relationship between the annular elastic seal member (25) and the variable nozzle vane (61).

[0153] According to the configuration of 18), it is not necessary to provide a member (obstruction member) such as the support member (9) that blocks a portion of the gas flow path (43C) on the upstream side of the variable nozzle vane (61), thereby improving the efficiency of the turbine (2). According to the configuration of 18), it is not necessary to provide a obstruction member (support member 9), thereby suppressing unstable behavior of the variable nozzle vane (61) that occurs when the flow on the downstream side of the obstruction member in the gas flow path (43C) is disturbed by the obstruction member, thereby improving the reliability of the variable nozzle vane (61). Furthermore, according to the configuration of 18), it is not necessary to provide the obstruction member (support member 9) and the second plate-shaped member (8), thereby reducing the number of parts of the turbine (2).

[0154] 19) In some embodiments, the turbine (2) according to 18) above, a rear-end biasing member (21) disposed between the second housing (5) and the first plate-shaped member (7) and configured to bias the first plate portion (71) toward the gas flow path (43C), The first housing (4) extends radially of the turbine wheel (3) and includes an engaging portion (44) to which the outer peripheral edge portion (76) of the first plate portion (71) urged by the rear end side urging member (21) is engaged.

[0155] According to the configuration of 19), the first plate-shaped member 7 is biased by the rear-end biasing member 21, so that the outer peripheral edge 76 of the first plate portion 71 is pressed against the locked portion 44 of the first housing 4. That is, the first plate-shaped member 7 is held in place by frictional force generated between the outer peripheral edge 76 of the first plate portion 71 and the locked portion 44 of the first housing 4 due to the biasing force of the rear-end biasing member 21. This makes it possible to prevent the first plate-shaped member 7 from being displaced relative to the first housing 4 and the second housing 5.

[0156] 20) In some embodiments, the turbine (2) according to 18) or 19) above, The annular elastic seal member (25) is a first biasing plate portion (251) extending along the radial direction of the turbine wheel (3) and having at least an outer peripheral end portion abutting against the at least one tip side end surface (65); a second biasing plate portion (252) extending along the radial direction and having at least an outer peripheral end portion abutting against the tip-side opposing surface (45); and a connecting portion (253) that connects an inner peripheral end of the first urging plate portion (251) and an inner peripheral end of the second urging plate portion (252).

[0157] According to the configuration of 20), the annular elastic seal member (25) can apply a pressing load to the variable nozzle vane (61) and seal the gap (G3) between the tip end face (65) and the tip opposing surface (45) by bringing the first biasing plate portion (251) into contact with the tip end face (65) of the variable nozzle vane (61) and bringing the second biasing plate portion (252) into contact with the tip opposing surface (45) of the first housing (4). In addition, the annular elastic seal member (25) includes a connecting portion (253) that connects an inner peripheral end portion of the first biasing plate portion (251) and an inner peripheral end portion of the second biasing plate portion (252), and therefore has an opening shape that opens outward in the radial direction of the turbine wheel (3). The annular elastic sealing member (25) having this opening shape is such that the first urging plate portion (251) and the second urging plate portion (252) are pushed apart in the axial direction of the turbine wheel (3) by the pressure of the gas flowing radially outside the annular elastic sealing member (25), thereby effectively sealing the gap (G3) between the tip side end face (65) and the tip side opposing face (45).

[0158] 21) In some embodiments, the turbine (2) according to any one of 18) to 20) above, The at least one variable nozzle vane (61) a tip-side end surface (65) facing the tip-side facing surface (45); a hub-side end surface (66) facing a flow path surface (72) of the first plate portion (71) facing the gas flow path (43C); a rotation shaft portion (67) extending from the hub-side end surface (66) along the rotation axis (RC) of the variable nozzle vane (61), The annular elastic seal member (25) has a contact portion (254) that contacts the tip side end surface (65) at least at a radial position through which the rotation axis (RC) of the variable nozzle vane (61) passes.

[0159] According to the configuration of 21), the radial position of the abutment portion 254, on which the biasing force of the annular elastic seal member 25 acts, is aligned with the radial position of the rotation axis RC of the variable nozzle vane 61, thereby effectively sealing the gap G3 between the tip end surface 65 and the leading end opposing surface 45. In particular, when the variable nozzle vane 61 is closed, gas leakage from the gap G3, which has a large impact on performance degradation of the turbine 2, can be effectively suppressed, thereby suppressing performance degradation of the turbine 2.

[0160] 22) In some embodiments, the turbine (2) according to 21) above, The seal further includes a positioning portion (26) provided on the inner peripheral side of the annular elastic seal member (25) to limit the radial position of the annular elastic seal member (25).

[0161] According to the configuration of 22), the positioning portion 26 restricts the radial position of the annular elastic seal member 25, thereby easily aligning the radial position where the biasing force of the annular elastic seal member 25 acts with the radial position through which the rotation axis RC of the variable nozzle vane 61 passes. Furthermore, restricting the radial position of the annular elastic seal member 25 with the positioning portion 26 can prevent the radial position where the biasing force of the annular elastic seal member 25 acts from shifting. By preventing the radial position where the biasing force of the annular elastic seal member 25 acts from shifting, gas leakage from the gap G3 between the tip-side end surface 65 and the leading-end opposing surface 45 can be effectively prevented, thereby preventing a decrease in performance of the turbine 2.

[0162] 23) A turbocharger (1) according to at least one embodiment of the present disclosure includes: A turbine (2) according to any one of 1) to 22) above; and a centrifugal compressor (12) configured to be driven by the turbine (2).

[0163] According to the configuration of 23), damage to the members forming the exhaust gas flow path (gas flow path 43A) of the turbine (2) due to thermal deformation can be suppressed, thereby improving the reliability of the turbocharger (1) equipped with the turbine (2). [Explanation of symbols]

[0164] 1 turbocharger 2 turbines 3 Turbine Wheel 4. First Housing 5 Second Housing 6 Variable nozzle unit 7 First plate-shaped member 8 Second plate-shaped member 9 Support member 10 Internal combustion engine system 11 Internal combustion engine 12 Centrifugal compressor 13 Impeller 14 Compressor housing 15 Rotating shaft 16 Bearings 21 Rear end biasing member 21A, 22A Disc spring 22 Front end biasing member 22B, 25 Sealing member 23 Annular plate member 24,26 Positioning part 31 Hub 32 Turbine blades 41 Scroll flow passage 42 Exhaust gas discharge flow path 43 Interior Space 43A, 43C gas flow path 43B 1st space 44 Locked part (radial extending part) 45 Tip side facing surface 46 Contact part 46A Contact surface 47 Shroud section 47A Shroud surface 51 Opposite surface on rear end side 61 Variable nozzle vane 62 Annular member 63 Link member 64 Wing surface 65 Chip side end face 66 Hub side end face 67 Rotating shaft 68 Drive mechanism 69 Control Device 71 1st plate part 72 1st flow path surface 73 1st back 74 Through Hole 75 Inner edge 76 Outer edge 81 2nd plate part 81B Thick part 81C Thin section 82 2nd flow path surface 83 2nd back 84 Center hole 85A Recess 85B Hole 91 one end 92 other end 92A Step surface 92B Insertion section D1,D2 Inner diameter G1 First gap G2, G3 gap LA,LD axis line P1 rear end RC rotation axis

Claims

1. a first housing having a scroll flow passage; a turbine wheel provided on the inner circumferential side of the scroll flow passage; a first plate-shaped member including an annular first plate portion; a second plate-shaped member including an annular second plate portion disposed facing the first plate portion and closer to a tip end of the turbine wheel in an axial direction than the first plate portion, and forming a gas flow path from the scroll flow path toward the turbine wheel between the first plate portion and the second plate portion; at least one variable nozzle vane disposed in the gas flow path and rotatably supported by the first plate-shaped member or the second plate-shaped member; a second housing disposed closer to a rear end of the turbine wheel in the axial direction than the first plate-shaped member; a rear-end biasing member disposed between the second housing and the first plate-shaped member and configured to bias the first plate portion toward the gas flow path; at least one support member provided in the gas flow path, one end of which is connected to one of the first plate portion or the second plate portion and the other end of which abuts against the other of the first plate portion or the second plate portion; A turbine comprising:

2. The first housing includes: a tip-side opposing surface that faces a back surface of the second plate portion opposite to a flow path surface that faces the gas flow path, with a gap therebetween; an annular abutment portion protruding from the tip-side opposing surface and abutting against the back surface of the second plate portion, The turbine of claim 1 .

3. the annular contact portion has an annular contact surface that contacts the back surface of the second plate portion at least at a radial position through which the axis of the support member passes. The turbine of claim 2 .

4. The first housing includes: a cylindrical shroud portion that is inserted into a center hole of the second plate portion and covers the turbine wheel, A turbine according to any one of claims 1 to 3.

5. the other plate portion has a recess formed in a flow path surface facing the gas flow path, the recess having a bottom surface against which the other end of the at least one support member abuts. A turbine according to any one of claims 1 to 3.

6. The first housing includes: a cylindrical shroud portion that is inserted into a center hole of the second plate portion and covers the turbine wheel, The second plate portion has an inner diameter larger than that of the first plate portion. The turbine of claim 5 .

7. The first housing includes: a cylindrical shroud portion that is inserted into a center hole of the second plate portion and covers the turbine wheel, The second plate portion is a thick portion having the recess; a thin-walled portion provided on the second plate portion closer to the inner circumferential side than the thick-walled portion, the thin-walled portion having a thickness smaller than that of the thick-walled portion in the axial direction of the turbine wheel, The turbine of claim 5 .

8. the other plate portion has a hole formed in a flow path surface facing the gas flow path, The other end of the at least one support member a step surface abutting on the flow path surface; an insertion portion that protrudes beyond the step surface and is inserted into the hole portion, A turbine according to any one of claims 1 to 3.

9. The at least one support member has one end connected to the first plate portion and the other end abutting the second plate portion. A turbine according to any one of claims 1 to 3.

10. a first housing having a scroll flow passage; a turbine wheel provided on the inner circumferential side of the scroll flow passage; a first plate-shaped member including an annular first plate portion; a second plate-shaped member including an annular second plate portion disposed facing the first plate portion and closer to a tip end of the turbine wheel in an axial direction than the first plate portion, and forming a gas flow path from the scroll flow path toward the turbine wheel between the first plate portion and the second plate portion; at least one variable nozzle vane disposed in the gas flow path and rotatably supported by the first plate-shaped member or the second plate-shaped member; a second housing disposed closer to a rear end of the turbine wheel in the axial direction than the first plate-shaped member; a front-end biasing member disposed between a back surface of the second plate portion opposite to a flow path surface facing the gas flow path and a tip-side opposing surface of the first housing opposing the back surface of the second plate portion across a gap, the front-end biasing member configured to bias the second plate portion toward the gas flow path; Equipped with a rear-end biasing member disposed between the second housing and the first plate-shaped member and configured to bias the first plate portion toward the gas flow path; the first housing includes a locked portion that extends along a radial direction of the turbine wheel and to which an outer peripheral edge portion of the first plate portion that is biased by the rear end side biasing member is locked, the front-end biasing member includes an annular elastic seal member that abuts against the back surface and the tip-end opposing surface of the second plate portion, The annular elastic seal member is a first biasing plate portion extending along a radial direction of the turbine wheel and having at least an outer peripheral end portion abutting against the back surface of the second plate portion; a second biasing plate portion extending along the radial direction and having at least an outer peripheral end portion abutting against the tip-side opposing surface; a connecting portion that connects an inner peripheral end portion of the first biasing plate portion and an inner peripheral end portion of the second biasing plate portion, The at least one variable nozzle vane is a hub-side end surface of the first plate portion that faces the flow path surface that faces the gas flow path; a rotation shaft portion extending from the hub-side end surface along a rotation axis of the variable nozzle vane, the first biasing plate portion has an abutment portion that abuts against the back surface of the second plate portion at least at a radial position through which the rotation axis of the variable nozzle vane passes. Turbine.

11. A first housing having a scroll flow path; a turbine wheel provided on the inner circumferential side of the scroll flow passage; a first plate-shaped member including an annular first plate portion; a second plate-shaped member including an annular second plate portion disposed facing the first plate portion and closer to a tip end of the turbine wheel in an axial direction than the first plate portion, and forming a gas flow path from the scroll flow path toward the turbine wheel between the first plate portion and the second plate portion; at least one variable nozzle vane disposed in the gas flow path and rotatably supported by the first plate-shaped member or the second plate-shaped member; a second housing disposed closer to a rear end of the turbine wheel in the axial direction than the first plate-shaped member; a front-end biasing member disposed between a back surface of the second plate portion opposite to a flow path surface facing the gas flow path and a tip-side opposing surface of the first housing opposing the back surface of the second plate portion across a gap, the front-end biasing member configured to bias the second plate portion toward the gas flow path; Equipped with The at least one variable nozzle vane is a tip side end surface of the second plate portion facing the flow path surface with a gap therebetween; a projection projecting from the tip-side end surface at least at a radial position through which the rotation axis of the variable nozzle vane passes and abutting on the flow path surface of the second plate portion, Turbine.

12. A first housing having a scroll flow path; a turbine wheel provided on the inner circumferential side of the scroll flow passage; a first plate-shaped member including an annular first plate portion; a second plate-shaped member including an annular second plate portion disposed facing the first plate portion and closer to a tip end of the turbine wheel in an axial direction than the first plate portion, and forming a gas flow path from the scroll flow path toward the turbine wheel between the first plate portion and the second plate portion; at least one variable nozzle vane disposed in the gas flow path and rotatably supported by the first plate-shaped member or the second plate-shaped member; a second housing disposed closer to a rear end of the turbine wheel in the axial direction than the first plate-shaped member; a front-end biasing member disposed between a back surface of the second plate portion opposite to a flow path surface facing the gas flow path and a tip-side opposing surface of the first housing opposing the back surface of the second plate portion across a gap, the front-end biasing member configured to bias the second plate portion toward the gas flow path; Equipped with The at least one variable nozzle vane is a hub-side end surface of the first plate portion facing the gas flow path via a gap; a rotation shaft portion extending from the hub-side end surface along a rotation axis of the variable nozzle vane, The rotor further includes an annular plate member disposed between the flow path surface of the first plate portion and the hub-side end surface and surrounding the rotary shaft portion. Turbine.

13. a positioning portion provided on an inner peripheral side of the front-end-side biasing member to limit a radial position of the front-end-side biasing member; The turbine of claim 10.

14. a first housing having a scroll flow passage; a turbine wheel provided on the inner circumferential side of the scroll flow passage; a first plate-like member including an annular first plate portion disposed opposite a tip-side opposing surface formed in the first housing at a radial position between the scroll passage and the turbine wheel, and forming a gas passage from the scroll passage toward the turbine wheel together with the tip-side opposing surface; at least one variable nozzle vane disposed in the gas flow path and rotatably supported by the first plate-shaped member; a second housing disposed closer to a rear end of the turbine wheel in an axial direction than the first plate-shaped member; an annular elastic seal member that abuts against the tip side end surface and the tip side opposing surface of the at least one variable nozzle vane; Equipped with a rear-end biasing member disposed between the second housing and the first plate-shaped member and configured to bias the first plate portion toward the gas flow path; the first housing includes a locked portion that extends along a radial direction of the turbine wheel and to which an outer peripheral edge of the first plate portion that is biased by the rear end side biasing member is locked, Turbine.

15. A first housing having a scroll flow path; a turbine wheel provided on the inner circumferential side of the scroll flow passage; a first plate-like member including an annular first plate portion disposed opposite a tip-side opposing surface formed in the first housing at a radial position between the scroll passage and the turbine wheel, and forming a gas passage from the scroll passage toward the turbine wheel together with the tip-side opposing surface; at least one variable nozzle vane disposed in the gas flow path and rotatably supported by the first plate-shaped member; a second housing disposed closer to a rear end of the turbine wheel in an axial direction than the first plate-shaped member; an annular elastic seal member that abuts against the tip side end surface and the tip side opposing surface of the at least one variable nozzle vane; Equipped with The annular elastic seal member is a first biasing plate portion extending along a radial direction of the turbine wheel and having at least an outer peripheral end portion abutting against the at least one tip side end surface; a second biasing plate portion extending along the radial direction and having at least an outer peripheral end portion abutting against the tip-side opposing surface; a connecting portion connecting an inner peripheral end portion of the first biasing plate portion and an inner peripheral end portion of the second biasing plate portion, Turbine.

16. A first housing having a scroll flow path; a turbine wheel provided on the inner circumferential side of the scroll flow passage; a first plate-like member including an annular first plate portion disposed opposite a tip-side opposing surface formed in the first housing at a radial position between the scroll passage and the turbine wheel, and forming a gas passage from the scroll passage toward the turbine wheel together with the tip-side opposing surface; at least one variable nozzle vane disposed in the gas flow path and rotatably supported by the first plate-shaped member; a second housing disposed closer to a rear end of the turbine wheel in an axial direction than the first plate-shaped member; an annular elastic seal member that abuts against the tip side end surface and the tip side opposing surface of the at least one variable nozzle vane; Equipped with The at least one variable nozzle vane is a tip side end facing the tip side facing surface; a hub-side end surface of the first plate portion that faces a flow path surface facing the gas flow path; a rotation shaft portion extending from the hub-side end surface along a rotation axis of the variable nozzle vane, the annular elastic seal member has an abutment portion that abuts against the tip side end at least at a radial position through which the rotation axis of the variable nozzle vane passes, a positioning portion provided on an inner peripheral side of the annular elastic seal member to limit a radial position of the annular elastic seal member; Turbine.

17. A turbine according to any one of claims 1, 2, 3, 10, 11 and 14; a centrifugal compressor configured to be driven by the turbine; A turbocharger comprising:

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