Turbine and turbocharger

Abstract

This turbine comprises: a turbine wheel; a first housing; a second housing that forms a gas flow path between the first housing and the second housing; a nozzle device including a first plate-shaped member, which includes an annular first plate part having a first flow path surface facing the gas flow path and a back surface facing a faced surface of the second housing, and a nozzle vane, which extends along the axial direction in the gas flow path; and a first biasing member that biases the nozzle device toward the first housing positioned on the other side in the axial direction with respect to the gas flow path. The second housing includes: a placement surface on which the first biasing member is placed on the other side in the axial direction with respect to the faced surface; and a protruding part having a protruding end surface, which abuts the first housing in the axial direction, on one side in the axial direction with respect to the placement surface.

Description

Turbines and turbochargers

[0001] This application claims priority to Japanese Patent Application No. 2024-089368, filed on May 31, 2024, with the Japan Patent Office, the contents of which are incorporated herein by reference.

[0002] A known turbocharger (supercharger) that supercharges the intake air of an internal combustion engine by utilizing the energy of the exhaust gas from the engine is equipped with a variable geometry turbine (see, for example, Patent Document 1). The variable geometry turbine has a plurality of nozzle vanes arranged circumferentially around the turbine wheel in an exhaust gas passage that sends exhaust gas from a scroll passage of the turbine to a 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). The 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] Patent No. 5206307

[0004] The variable geometry turbine described in Patent Document 1 discloses that the turbine housing and the bearing housing are fastened with bolts while their abutment surfaces are in contact with each other. In the variable geometry turbine described in Patent Document 1, the abutment surface of the bearing housing is located farther from the turbine housing than the end face that houses the variable nozzle unit. In this case, the bearing housing is easy to process. However, in the variable geometry turbine described in Patent Document 1, there is a risk that the biasing force will decrease due to thermal elongation during turbine operation.

[0005] In view of the above circumstances, at least one embodiment of the present disclosure aims to provide a turbine that can suppress a decrease in biasing force due to thermal expansion during operation of the turbine, and a turbocharger including the turbine.

[0006] a first plate-like member including an annular first plate portion having a first flow path surface facing the gas flow path and a back surface formed on one axial side of the turbine wheel relative to the first flow path surface and facing an opposed surface of the second housing across an axial gap; and a nozzle device including at least one nozzle vane fixed to or rotatably supported on the first plate portion and extending along the axial direction in the gas flow path; and a first biasing member disposed between the first plate-like member and the second housing and configured to bias the nozzle device toward the first housing located on the other axial side of the gas flow path, wherein the second housing has: a mounting surface on which the first biasing member is mounted, on the other axial side of the opposed surface; a protrusion that protrudes radially outward from the opposed surface and toward the other side in the axial direction than the opposed surface, and that has a pointed end surface that abuts against the first housing in the axial direction on one side of the axial direction than the mounting surface.

[0007] A turbocharger according to at least one embodiment of the present disclosure includes: the turbine; and a centrifugal compressor configured to be driven by the turbine.

[0008] According to at least one embodiment of the present disclosure, there is provided a turbine capable of suppressing a decrease in biasing force due to thermal expansion during operation of the turbine, and a turbocharger including the turbine.

[0009] FIG. 1 is a schematic diagram of an internal combustion engine system including a turbocharger according to an embodiment of the present disclosure; FIG. 2 is a schematic cross-sectional view taken along the axis of a turbine according to an embodiment of the present disclosure; FIG. 3 is a schematic cross-sectional view of a nozzle device included in the turbine according to an embodiment of the present disclosure; FIG. 4 is a schematic cross-sectional view showing a half section along the axis of a turbine according to an embodiment of the present disclosure; FIG. 5 is a schematic cross-sectional view showing a half section along the axis of a turbine according to a comparative example; FIG. 6 is an explanatory view for explaining a change in the axial length of an axial gap in which a first biasing member of a turbine according to a comparative example is disposed; FIG. 7 is an explanatory view for explaining a change in the axial length of an axial gap in which a first biasing member of a turbine according to an embodiment of the present disclosure is disposed; FIG. 8 is a schematic cross-sectional view showing a half section along the axis of a turbine according to an embodiment of the present disclosure;

[0010] 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.

[0011] (Turbocharger) FIG. 1 is a schematic diagram of an internal combustion engine system 10 including a turbocharger 1 according to an embodiment of the present disclosure. 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 as long as it is capable of converting working fluid energy into mechanical power (e.g., rotational force). The turbine 2 may be configured in combination with a mechanism or device other than a centrifugal compressor 12. Furthermore, the application of the turbine 2 does not need to be limited.

[0012] 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.

[0013] The centrifugal compressor 12 includes an impeller 13 and a compressor housing 14 configured to rotatably accommodate the impeller 13. The turbine 2 includes 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.

[0014] 1 , the turbocharger 1 further includes a rotating shaft 15 to which the turbine wheel 3 is connected on one side and the impeller 13 is connected on the other side, 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.

[0015] 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 the 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.

[0016] 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.

[0017] 1, the impeller 13 is connected to the other side of the rotary shaft 15 and is therefore rotatable integrally with the rotary shaft 15 about the axis of the impeller 13. The impeller 13 is a centrifugal impeller 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.

[0018] (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.

[0019] 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.

[0020] 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.

[0021] 2 is a schematic cross-sectional view taken along the axis line LA of the turbine 2 according to an embodiment of the present disclosure. Hereinafter, the direction in which the axis line 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 line LA will be referred to as the radial direction of the turbine wheel 3 (turbine 2), and the circumferential direction around the axis line LA will be referred to as the circumferential direction of the turbine wheel 3 (turbine 2). Hereinafter, the side in the axial direction of the turbine wheel 3 (turbine 2) where the first housing 4 is located relative to the second housing 5 (the right side, the other side in FIG. 2 ) will be defined as the first side, and the side where the second housing 5 is located relative to the first housing 4, i.e., the side opposite to the first side (the left side, one side in FIG. 2 ), will be defined as the second side.

[0022] (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 around 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.

[0023] (Scroll passage, exhaust gas discharge passage) 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 consists of 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 first side along the axial direction of the turbine wheel 3.

[0024] Fastening the first housing 4 and the second housing 5 together forms an internal space 43 between the first housing 4 and the second housing 5, connecting the scroll passage 41 and the exhaust gas discharge passage 42. The turbine wheel 3 is housed in the 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. The internal space 43 includes a gas passage 43A that runs from the scroll passage 41 to the turbine wheel 3.

[0025] The exhaust gas discharged from the internal combustion engine 11 is guided to the turbine wheel 3 via the scroll passage 41, and drives the turbine wheel 3 to rotate. The exhaust gas that has driven the turbine wheel 3 to rotate is discharged to the outside of the first housing 4 (turbine 2) via the exhaust gas discharge passage 42.

[0026] (Nozzle Device) Figure 3 is a schematic diagram of the nozzle device 6 included in the turbine 2 according to an embodiment of the present disclosure. As shown in Figure 2, the turbine 2 further includes the nozzle device 6 housed on the outer circumferential side of the turbine wheel 3 in the internal space 43 described above. The nozzle device 6 forms the gas flow path 43A described above and serves to straighten 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 outer side) of the turbine wheel 3.

[0027] The nozzle device 6 includes a first plate-shaped member (nozzle mount) 7 and at least one (plurality of nozzle vanes in the illustrated example) nozzle vane 61. In the embodiment shown in Figures 2 and 3, the nozzle device 6 is a variable nozzle device 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. In the embodiment shown in Figures 2 and 3, the nozzle device 6 includes the first plate-shaped member 7, at least one (plurality of variable nozzle vanes in the illustrated example) variable nozzle vane 61A, an annular member (drive ring) 62, at least one (plurality of link members (lever plates)) 63, and at least one (for example, plural) support member (nozzle support) 9.

[0028] (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 circumferential side of the turbine wheel 3. A first flow path surface 72 that faces the gas flow path 43A is formed on a first side in the axial direction of the first plate portion 71, and a back surface 73 is formed on a second side in the axial direction of the first plate portion 71, i.e., the side opposite to the first flow path surface 72. In the illustrated embodiment, each of the first flow path surface 72 and the back surface 73 is annular and extends along the circumferential direction of the turbine wheel 3.

[0029] 2 and 3 , the first housing 4 has a second flow path surface 44 facing the gas flow path 43A. The second flow path surface 44 is located on the first axial side of the first flow path surface 72 and faces the first flow path surface 72 across the gas flow path 43A. In the illustrated embodiment, the second flow path surface 44 is an annular surface extending along the circumferential direction of the turbine wheel 3. The gas flow path 43A is formed between the first flow path surface 72 and the second flow path surface 44. The exhaust gas introduced into the turbine 2 passes through the scroll flow path 41 and then the gas flow path 43A before being guided to the turbine wheel 3 and causing the turbine wheel 3 to rotate.

[0030] The second housing 5 has an opposed surface 51 that faces the back surface 73 of the first plate portion 71, with a first space 43B (axial gap) sandwiched between the opposed surface 51 and the back surface 73. The first space 43B is part of the internal space 43, and is formed on the axially opposite side (second side) of the first plate portion 71 from the gas flow path 43A.

[0031] (Variable Nozzle Vane) Each of the multiple variable nozzle vanes 61A is disposed in the gas flow path 43A and is supported by a first plate portion 71 (first plate-shaped member 7) so as to be rotatable about its respective rotation axis RC. Each of the multiple variable nozzle vanes 61A includes a blade surface 64 facing the gas flow path 43A, a tip-side end face 65 formed at a first end of the blade surface 64 in the axial direction, a hub-side end face 66 formed at a second 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 second end in the axial direction along the rotation axis RC of the variable nozzle vane 61A. The multiple variable nozzle vanes 61A are disposed at intervals in the circumferential direction of the turbine wheel 3. The tip-side end face 65 of each of the multiple variable nozzle vanes 61A faces the second flow path surface 44 via a gap, and the hub-side end face 66 faces the first flow path surface 72 via a gap.

[0032] (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.

[0033] 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 a drive force, an air cylinder that transmits the drive force, and the like.

[0034] 3, the nozzle device 6 includes link members (lever plates) 63, the number of which is the same as the number of variable nozzle vanes 61A. Each of the plurality of link members 63 is disposed 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 61A, and is configured to change the blade angle of the variable nozzle vane 61A connected to the other end 632 in conjunction with the rotation of the annular member 62.

[0035] 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 configured to fit loosely into the groove 621A. The first plate portion 71 is formed with a plurality of through holes 74 that penetrate the first flow path surface 72 and the 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 is formed with the same number of through holes 74 as the number of variable nozzle vanes 61A and link members 63. The other end 632 of each link member 63 is connected to the tip end (second end) of the rotary shaft portion 67 of the variable nozzle vane 61A corresponding to that link member 63, which is inserted through the through hole 74.

[0036] When the annular member 62 is rotated to one side in the circumferential direction of the turbine wheel 3, the variable nozzle vanes 61A adjacent to each other in the circumferential direction move (rotate) away from each other, increasing the flow path cross-sectional area of ​​the gas flow path 43A between the variable nozzle vanes 61A. On the other hand, when the annular member 62 is rotated to the other side in the circumferential direction of the turbine wheel 3, the variable nozzle vanes 61A adjacent to each other in the circumferential direction move (rotate) toward each other, decreasing the flow path cross-sectional area of ​​the gas flow path 43A between the variable nozzle vanes 61A.

[0037] The nozzle device 6 transmits a driving force from outside the nozzle device 6 (a driving mechanism 68) to the plurality of variable nozzle vanes 61A via the annular member 62 and the plurality of link members 63, thereby rotating the plurality of variable nozzle vanes 61A about their respective rotation axes RC and changing their respective blade angles, thereby adjusting the flow path cross-sectional area of ​​the gas flow path 43A. 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 flow path 43A using the nozzle device 6, thereby controlling the boost pressure of the turbine 2.

[0038] 4 is a schematic cross-sectional view showing a half cross section along the axis line LA of the turbine 2 according to an embodiment of the present disclosure. As shown in FIG. 4 , the turbine 2 includes a first biasing member 8 that is disposed between the second housing 5 and the first plate-shaped member 7 and is configured to bias the nozzle device 6 toward the first housing 4 that is located on a first axial side of the gas flow path 43A.

[0039] In the embodiment shown in FIG. 4 , the first biasing member 8 includes a disc spring 8A that abuts against an end face 52 formed radially inward of the opposed surface 51 of the second housing 5 and an end face 75A of the inner peripheral edge 75 of the first plate portion 71 opposite the first flow path surface 72. The end face 75A is formed radially inward of the back surface 73. The disc spring 8A 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. The axial length of the axial gap in which the first biasing member 8 is disposed is defined as L4. The axial length L4 is the axial length between the end face 52 and the end face 75A.

[0040] 4 , the first housing 4 includes a radially extending portion 47 extending along the radial direction of the turbine wheel 3. The radially extending portion 47 has a scroll passage surface 471 extending radially outward from the second axial end P1 of the scroll passage 41. The 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 47, and the first plate member 7 biased by the first biasing member 8 is not hindered from moving along the axial direction of the turbine wheel 3 by the radially extending portion 47.

[0041] (Support Member) Each of the multiple support members 9 is provided in the gas flow path 43A, has one end 91 connected to the first plate portion 71, and the other end 92 abuts against the second flow path surface 44. Each of the multiple support members 9 is disposed in the gas flow path 43A upstream of the variable nozzle vane 61A, i.e., outward of the variable nozzle vane 61A in the radial direction of the turbine wheel 3. Each of the multiple support members 9 supports the first flow path surface 72 and the second flow path surface 44 while keeping them spaced apart from each other, forming a first gap G1 between the first flow path surface 72 and the second flow path surface 44. 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.

[0042] Because the first housing 4 is fastened to the second housing 5 via the fastening members 18, heat input from the exhaust gas during operation of the turbine 2 causes thermal expansion toward the other axial side (first side) so as to widen the gas flow path 43A. The first housing 4 receives a larger amount of heat input from the exhaust gas during operation of the turbine 2 than the first plate-shaped member 7, which is located radially inward. The outer circumferential side of the first plate-shaped member 7 thermally expands toward the one axial side (second side) so as to widen the gas flow path 43A due to heat input from the exhaust gas during operation of the turbine 2. In contrast, the inner circumferential side of the first plate-shaped member 7 thermally expands so as to widen the axial length L4 in response to the first housing 4 thermally expanding toward the other axial side (first side) due to heat input from the exhaust gas during operation of the turbine 2.

[0043] 4 , in the turbine 2 according to some embodiments, the first housing 4 has a protruding portion that protrudes further toward the second axial direction than the radially extending portion 47, and is fastened to the second housing 5 via fastening members (fastening bolts) 18. The second housing 5 includes a mounting surface 53 (end surface 52 in the illustrated example) on which the first biasing member 8 is mounted on a first axial side of the opposed surface 51, and a protruding portion 54 that protrudes radially outward from the opposed surface 51 toward the first axial side than the opposed surface 51. The protruding portion 54 has a protruding end surface 541 that abuts against the first housing 4 in the axial direction on a second axial side of the mounting surface 53.

[0044] According to the inventors' new findings, by providing the axial position of the protruding end face 541 at a position closer to the mounting surface 53 on the one axial side (second side) than the mounting surface 53, it is possible to reduce the effect that thermal expansion of the first housing 4 during operation of the turbine 2 has on the axial gap in which the first biasing member 8 is disposed. In other words, it is possible to prevent the axial length L4 from increasing due to thermal expansion of the first housing 4 during operation of the turbine 2.

[0045] 5 is a schematic cross-sectional view showing a half cross section along the axis LA of a turbine 02 according to a comparative example. The turbine 02 according to the comparative example differs from the turbine 2 in that a surface 0541 corresponding to the protruding end surface 541 of the turbine 2 described above is located on the one side (second side) in the axial direction relative to the opposed surface 51. The turbine 02 according to the comparative example does not have a protruding portion 54, and therefore the second housing 5 is more easily workable than the turbine 2.

[0046] FIG. 6 is an explanatory diagram illustrating a change in the axial length L4 of the axial gap in which the first biasing member 8 of the turbine 02 according to the comparative example is disposed. FIG. 7 is an explanatory diagram illustrating a change in the axial length L4 of the axial gap in which the first biasing member 8 of the turbine 2 according to an embodiment of the present disclosure is disposed. In FIGS. 6 and 7 , the change in the axial length L4 over time during operation of the turbine 2 is shown in a graph with the horizontal axis representing time T (T1 to T4) and the horizontal axis representing the axial length L4. On the vertical axis, the axial length L4 before the start of operation of the turbine 2 is defined as an initial length P0, and the positive (+) direction indicates the side where the axial length L4 is larger than the initial length P0, and the negative (−) direction indicates the side where the axial length L4 is smaller than the initial length P0.

[0047] As shown in Fig. 6 , in the turbine 02 according to the comparative example, the axial length L4 may become positive (+) during operation of the turbine 02, and there is a risk that the biasing force of the first biasing member 8 may not act effectively on the nozzle device 6. In contrast, as shown in Fig. 7 , in the turbine 2 according to the present disclosure, the axial length L4 remains in the negative (-) direction during operation of the turbine 2 and does not become positive (+), and therefore the biasing force of the first biasing member 8 acts effectively on the nozzle device 6.

[0048] The above-described turbine 2 can reduce the effect that thermal expansion of the first housing 4 during operation of the turbine 2 has on the axial gap in which the first biasing member 8 is disposed. This makes it possible to suppress a decrease in the biasing force of the first biasing member 8 due to thermal expansion during operation of the turbine 2.

[0049] As shown in FIG. 4 , in some embodiments, the turbine 2 is configured such that, when the diameter of the turbine wheel 3 is defined as D1 and the axial length between the mounting surface 53 and the end face 541 is defined as a first length L1, the ratio L1 / D1 of the first length L1 to the diameter D1 satisfies the condition L1 / D1≦0.15.

[0050] When the condition L1 / D1≦0.15 is satisfied, it is possible to effectively reduce the influence that thermal expansion of the first housing 4 has on the axial gap in which the first biasing member 8 is disposed during operation of the turbine 2. If the first length L1 is large, the axial length of the portion of the first housing 4 having a surface that abuts against the protruding end surface 541 becomes large, which increases the thermal expansion of the first housing 4 in the axial direction and increases the influence that this has on the axial gap in which the first biasing member 8 is disposed.

[0051] As shown in FIG. 4, the turbine 2 according to some embodiments is configured such that the ratio L1 / D1 of the first length L1 to the diameter D1 satisfies the condition L1 / D1≧0.05.

[0052] When the condition L1 / D1≧0.05 is satisfied, it is possible to suppress a reduction in the biasing force of the first biasing member 8 due to heat input during operation of the turbine 2. If the first length L1 is small, the axial length of the portion having a surface that abuts against the protruding end surface 541 of the first housing 4 becomes small, and therefore the amount of reduction in the axial length L4 described above due to thermal deformation of the first housing 4, the support member 9, and the first plate-like member 7 becomes large, and there is a risk that the first biasing member 8 will be compressed to the extent that it loses its spring function.

[0053] As shown in FIG. 4, in some embodiments, the turbine 2 is configured such that, when the axial length between the first flow path surface 72 of the first plate portion 71 and the tip surface 541 is defined as the second length L2, the ratio L2 / D1 of the second length L2 to the diameter D1 satisfies the condition L2 / D1≦0.20.

[0054] When the condition L2 / D1≦0.20 is satisfied, it is possible to effectively reduce the effect that thermal expansion of the first housing 4 during operation of the turbine 2 has on the axial gap in which the first biasing member 8 is disposed. If the second length L2 is large, the axial length of the portion of the first housing 4 that has a surface that abuts against the protruding end surface 541 becomes large, which increases the axial thermal expansion of the first housing 4 and increases the effect that it has on the axial gap in which the first biasing member 8 is disposed.

[0055] As shown in FIG. 4, in some embodiments, when the axial length between the second flow path surface 44 and the tip surface 541 is defined as a third length L3, the turbine 2 is configured such that the ratio L3 / D1 of the third length L3 to the diameter D1 satisfies the condition L3 / D1≦0.35.

[0056] When the condition L3 / D1≦0.35 is satisfied, it is possible to effectively reduce the effect that thermal expansion of the first housing 4 during operation of the turbine 2 has on the axial gap in which the first biasing member 8 is disposed. If the third length L3 is large, the axial length of the portion of the first housing 4 that has a surface that abuts against the protruding end surface 541 becomes large, which increases the axial thermal expansion of the first housing 4 and increases the effect that this has on the axial gap in which the first biasing member 8 is disposed.

[0057] 4 , in the turbine 2 according to some embodiments, each of the plurality of nozzle vanes 61 described above includes a variable nozzle vane 61A, which is a variable nozzle vane rotatably supported on the first plate portion 71. The nozzle device 6 described above includes the single support member 9 described above. When the nozzle vanes 61 are variable nozzle vanes 61A, the turbine 2 can suppress a decrease in the biasing force due to thermal elongation during operation of the turbine 2.

[0058] Fig. 8 is a schematic cross-sectional view showing a half cross-section taken along the axis line LA of the turbine 2 according to one embodiment of the present disclosure. In the turbine 2 according to some embodiments, as shown in Fig. 8, each of the plurality of nozzle vanes 61 described above includes a fixed nozzle vane 61B, which is a fixed nozzle vane having one side connected to the first plate portion 71 and the other side abutting against the second flowpath surface 44. When the nozzle vane 61 is the fixed nozzle vane 61B, the turbine 2 can suppress a decrease in the biasing force due to thermal elongation during operation of the turbine 2. In the embodiment shown in Fig. 8, the nozzle device 6 does not include a support member 9.

[0059] 8 , the turbine 2 according to some embodiments includes a second biasing member 101 configured to bias the nozzle device 6 toward the first housing 4 located on a first axial side of the gas flow path 43A. The second biasing member 101 includes a disc spring that abuts against the back surface 73 of the first plate portion 71 and the opposed surface 51 of the second housing 5, respectively.

[0060] Even if the axial gap in which the first biasing member 8 is disposed increases due to thermal expansion of the first housing 4 during operation of the turbine 2, the biasing force on the nozzle device 6 is maintained by the second biasing member 101.

[0061] FIG. 9 is a schematic cross-sectional view along the axis LA of the turbine 2 according to an embodiment of the present disclosure. In some of the above-described embodiments, the first housing 4 has the second flow path surface 44. However, as shown in FIG. 9 , a second plate-shaped member 102 attached to the first housing 4 may have the second flow path surface 44. The second plate-shaped member (nozzle plate) 102 is disposed opposite the first plate portion 71 and includes an annular second plate portion 103 that forms a gas flow path 43A between itself and the first plate portion 71. The second plate portion 103 is disposed on a first side in the axial direction relative to the first plate portion 71 and extends along the circumferential direction of the turbine wheel 3 on the outer periphery side of the turbine wheel 3. The second flow path surface 44 that faces the gas flow path 43A is formed on a second side in the axial direction of the second plate portion 103.

[0062] 1 , a turbocharger 1 according to some embodiments includes the above-described turbine 2 and a centrifugal compressor 12 configured to be driven by the above-described turbine 2. The turbocharger 1 including the turbine 2 can reduce the effect that thermal expansion of the first housing 4 during operation of the turbine 2 has on the axial gap in which the first biasing member 8 is disposed, and can suppress a decrease in the biasing force of the first biasing member 8 due to thermal expansion during operation of the turbine 2.

[0063] In this specification, expressions expressing relative or absolute arrangements, such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial," not only strictly express such arrangements, 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 expressing that things are in an equal state, such as "identical," "equal," and "homogeneous," not only express a state in which there is a strict equivalence, but also express 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 expressing shapes such as a rectangular shape or a cylindrical shape not only express shapes such as a rectangular shape or a cylindrical shape in the strict geometric sense, but also express shapes including concave and convex portions, chamfered portions, etc., to the extent that the same effect is obtained. Furthermore, in this specification, the expressions "comprise," "include," or "have" a component are not exclusive expressions that exclude the presence of other components.

[0064] 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.

[0065] The contents of the above-described embodiments can be understood, for example, as follows.

[0066] 1) A turbine (2) according to at least one embodiment of the present disclosure includes: a turbine wheel (3); a first housing (4) having a scroll passage; a second housing (5) connected to the first housing (4), accommodating the turbine wheel (3) between the first housing (4) and the second housing (5), and forming a gas passage (43A) between the first housing (4) and the second housing (5) and extending from the scroll passage toward the turbine wheel (3); a first plate-like member (7) including an annular first plate portion (71) having a first passage surface (72) facing the gas passage (43A) and a back surface (73) formed on one axial side of the turbine wheel (3) with respect to the first passage surface (72) and facing an opposed surface (51) of the second housing (5) across an axial gap; and a nozzle device (6) fixed to or rotatably supported by the first plate portion (71) and including at least one nozzle vane (61) extending along the axial direction in the gas passage (43A). and a first biasing member (8) that is arranged between the first plate-like member (7) and the second housing (5) and is configured to bias the nozzle device (6) toward the first housing (4) that is located on the other side of the gas flow path (43A) in the axial direction, wherein the second housing (5) includes: a mounting surface (53) on which the first biasing member (8) is mounted on the other side of the opposed surface (51) in the axial direction; and a protruding portion (54) that protrudes radially outward from the opposed surface (51) toward the other side in the axial direction beyond the opposed surface (51), the protruding portion (54) having a protruding end surface (541) that abuts against the first housing (4) in the axial direction on the one side of the mounting surface (53) in the axial direction.

[0067] According to the configuration 1) above, and based on the new findings of the inventors, by providing the protruding end face (541) in the axial direction closer to the mounting surface (53) on the one axial side than the mounting surface (53), it is possible to reduce the effect of thermal expansion of the first housing (4) during operation of the turbine (2) on the axial gap in which the first biasing member (8) is disposed. This makes it possible to suppress a decrease in the biasing force of the first biasing member (8) due to thermal expansion during operation of the turbine (2).

[0068] 2) In some embodiments, the turbine (2) described in 1) above is configured such that, when the diameter of the turbine wheel (3) is defined as D1 and the length in the axial direction between the mounting surface (53) and the end face (541) is defined as a first length L1, the ratio L1 / D1 of the first length L1 to the diameter D1 satisfies the condition L1 / D1≦0.15.

[0069] According to the configuration of 2) above, when the condition L1 / D1≦0.15 is satisfied, it is possible to effectively reduce the influence of thermal elongation of the first housing (4) during operation of the turbine (2) on the axial gap in which the first biasing member (8) is disposed. If the first length L1 is large, the axial length of the portion of the first housing (4) having a surface that abuts against the protruding end surface (541) becomes large, which increases the axial thermal elongation of the first housing (4) and increases the influence on the axial gap in which the first biasing member (8) is disposed.

[0070] 3) In some embodiments, the turbine (2) according to 2) above is configured such that a ratio L1 / D1 of the first length L1 to the diameter D1 satisfies the condition L1 / D1≧0.05.

[0071] According to the configuration of 3) above, when the condition L1 / D1≧0.05 is satisfied, it is possible to suppress a reduction in the biasing force of the first biasing member (8) due to heat input during operation of the turbine (2). If the first length L1 is small, the axial length of the portion having a surface that abuts against the protruding end surface (541) of the first housing (4) becomes small, and therefore the reduction in the axial length (L4) due to thermal deformation of the first housing (4), the support member (9), and the first plate-shaped member (7) becomes large, and there is a risk that the first biasing member (8) will be compressed to the extent that it loses its spring function.

[0072] 4) In some embodiments, the turbine (2) according to any one of 1) to 3) above is configured such that, when the diameter of the turbine wheel (3) is defined as D1 and the length in the axial direction between the first flow path surface (72) and the tip end surface (541) of the first plate portion (71) is defined as a second length L2, the ratio L2 / D1 of the second length L2 to the diameter D1 satisfies the condition L2 / D1≦0.20.

[0073] According to the configuration of 4) above, when the condition L2 / D1≦0.20 is satisfied, it is possible to effectively reduce the influence of thermal expansion of the first housing (4) during operation of the turbine (2) on the axial gap in which the first biasing member (8) is disposed. If the second length L2 is large, the axial length of the portion of the first housing (4) having a surface that abuts against the protruding end surface (541) becomes large, which increases the axial thermal expansion of the first housing (4) and increases the influence on the axial gap in which the first biasing member (8) is disposed.

[0074] 5) In some embodiments, the turbine (2) according to any one of 1) to 4) above is configured such that, when a diameter of the turbine wheel (3) is defined as D1 and a length in the axial direction between a second flow path surface (44) facing the first flow path surface (72) across the gas flow path (43A) and the tip surface (541) is defined as a third length L3, a ratio L3 / D1 of the third length L3 to the diameter D1 satisfies the condition L3 / D1≦0.35.

[0075] According to the configuration of 5) above, when the condition L3 / D1≦0.35 is satisfied, it is possible to effectively reduce the influence of thermal elongation of the first housing (4) during operation of the turbine (2) on the axial gap in which the first biasing member (8) is disposed. If the third length L3 is large, the axial length of the portion of the first housing (4) having a surface that abuts against the protruding end surface (541) becomes large, which increases the axial thermal elongation of the first housing (4) and increases the influence on the axial gap in which the first biasing member (8) is disposed.

[0076] 6) In some embodiments, the turbine (2) is described in any one of 1) to 5) above, wherein the at least one nozzle vane (61) includes a variable nozzle vane (61A) rotatably supported on the first plate portion (71), and the nozzle device (6) includes at least one support member (9) connected on one side to the first plate portion (71) and abutting on the other side against a second flow path surface facing the first flow path surface (72) across the gas flow path (43A).

[0077] According to the configuration 6) above, in the turbine (2), when the nozzle vane (61) is a variable nozzle vane (61A), a decrease in the biasing force due to thermal elongation during operation of the turbine (2) can be suppressed.

[0078] 7) In some embodiments, in the turbine (2) described in any one of 1) to 5) above, the at least one nozzle vane (61) includes a fixed nozzle vane (61B) connected at one side to the first plate portion (71) and abutting at the other side against a second flow path surface (44) facing the first flow path surface (72) across the gas flow path (43A).

[0079] According to the configuration of 7) above, in the turbine (2), when the nozzle vanes (61) are fixed nozzle vanes (61B), reduction in the biasing force due to thermal elongation during operation of the turbine (2) can be suppressed.

[0080] 8) In some embodiments, the turbine (2) described in 7) above further includes a second biasing member (9) configured to bias the nozzle device (6) toward the first housing (4) located on the other axial side of the gas flow path, the second biasing member (101) abutting against each of the back surface (73) of the first plate portion (71) and the opposed surface (51) of the second housing (5).

[0081] According to the configuration of 8) above, even if the axial gap in which the first biasing member (8) is disposed increases due to thermal expansion of the first housing (4) during operation of the turbine (2), the biasing force on the nozzle device (6) is maintained by the second biasing member (101).

[0082] 9) A turbocharger (1) according to at least one embodiment of the present disclosure comprises: a turbine (2) according to any one of 1) to 8) above; and a centrifugal compressor (12) configured to be driven by the turbine (2).

[0083] According to the configuration of 9) above, it is possible to reduce the influence of thermal expansion of the first housing (4) during operation of the turbine (2) on the axial gap in which the first biasing member (8) is disposed, and it is possible to suppress a decrease in the biasing force of the first biasing member (8) due to thermal expansion during operation of the turbine (2).

[0084] REFERENCE SIGNS LIST 1 turbocharger 2 turbine 3 turbine wheel 4 first housing 5 second housing 6 nozzle device 7 first plate-shaped member 8 first biasing 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 bearing 18 fastening member 31 hub 32 turbine blade 41 scroll passage 42 exhaust gas discharge passage 43 internal space 43A gas passage 43B first space 44 second passage surface 51 opposed surface 53 mounting surface 54 protrusion 61 nozzle vane 61A variable nozzle vane 61B fixed nozzle vane 62 annular member 63 link member 64 blade surface 65 tip side end surface 66 hub side end surface 67 rotating shaft portion 68 Drive mechanism 69 Control device 71 First plate portion 72 First flow path surface 73 Back surface 74 Through hole 101 Second biasing member 102 Second plate-shaped member 541 Protruding end surface

Claims

a first housing having a scroll passage; a second housing connected to the first housing, accommodating the turbine wheel between the first housing and the first housing, and forming a gas passage from the scroll passage to the turbine wheel between the first housing and the first housing; a first plate-like member including an annular first plate portion having a first passage surface facing the gas passage and a back surface formed on one axial side of the turbine wheel relative to the first passage surface and facing an opposed surface of the second housing across an axial gap; and a nozzle device including at least one nozzle vane fixed to or rotatably supported on the first plate portion and extending along the axial direction in the gas passage; and a first biasing member arranged between the first plate-like member and the second housing and configured to bias the nozzle device toward the first housing located on the other axial side of the gas passage, wherein the second housing has: a mounting surface on which the first biasing member is mounted on the other axial side of the opposed surface; a protruding portion that protrudes radially outward from the opposed surface and toward the other side in the axial direction than the opposed surface, the protruding portion having a protruding end surface that abuts against the first housing in the axial direction on the one side in the axial direction than the mounting surface.

2. A turbine according to claim 1, wherein, when the diameter of the turbine wheel is defined as D1 and the length in the axial direction between the mounting surface and the end face is defined as a first length L1, the ratio L1 / D1 of the first length L1 to the diameter D1 satisfies the condition L1 / D1≦0.

15.

3. The turbine according to claim 2, wherein a ratio L1 / D1 of the first length L1 to the diameter D1 is configured to satisfy the condition L1 / D1≧0.

05.

4. A turbine as claimed in any one of claims 1 to 3, wherein, when the diameter of the turbine wheel is defined as D1 and the length in the axial direction between the first flow path surface and the tip end surface of the first plate portion is defined as a second length L2, the ratio L2 / D1 of the second length L2 to the diameter D1 satisfies the condition L2 / D1≦0.

20.

5. A turbine as claimed in any one of claims 1 to 3, wherein, when the diameter of the turbine wheel is defined as D1 and the length in the axial direction between the tip face and a second flow path surface that faces the first flow path surface across the gas flow path is defined as a third length L3, the ratio L3 / D1 of the third length L3 to the diameter D1 satisfies the condition L3 / D1≦0.

35.

6. A turbine according to any one of claims 1 to 3, wherein the at least one nozzle vane includes a variable nozzle vane rotatably supported on the first plate portion, and the nozzle device includes at least one support member connected at one side to the first plate portion and abutting at the other side against a second flow path surface opposing the first flow path surface across the gas flow path.

7. The turbine according to any one of claims 1 to 3, wherein the at least one nozzle vane includes a fixed nozzle vane connected at one side to the first plate portion and abutting at the other side against a second flow path surface opposite the first flow path surface across the gas flow path.

8. A turbine according to claim 7, further comprising a second biasing member configured to bias the nozzle device against the first housing located on the other side of the gas flow path in the axial direction, the second biasing member abutting against each of the back surface of the first plate portion and the opposed surface of the second housing.

9. A turbocharger comprising: a turbine according to any one of claims 1 to 3; and a centrifugal compressor configured to be driven by the turbine.

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