Variable capacity turbo and supercharger

Abstract

Efficiency of a turbine at low flow rate is improved. A variable capacity turbine has a turbine rotor, scroll flow path forming portions that form scroll flow paths, exhaust gas flow path forming portions that form exhaust gas flow paths for guiding exhaust gas from the scroll flow paths to the turbine rotor, and a variable nozzle unit that includes a plurality of nozzle vanes (6) disposed in the exhaust gas flow paths and configured to be able to rotate around respective rotation centers. The exhaust gas flow path forming portions include a first plate-shaped member (41) having a ring-shaped first plate portion (43), and a second plate-shaped member having a ring-shaped second plate portion disposed on the turbine outlet side in the axial direction of the turbine rotor compared to the first plate portion, and delimiting the exhaust gas flow paths between the second plate portion and the first plate portion. The first plate-shaped member is formed with at least one groove portion (7) extending from the inner periphery of the first plate portion to the outer periphery side in a hub side flow path surface of the first plate portion facing the exhaust gas flow paths.

Description

Technical Field

[0001] This disclosure relates to a variable capacity turbine and a turbocharger having the variable capacity turbine.

[0002] This application claims priority based on Japan Patent Application No. 2021-008190 filed on January 21, 2021, the contents of which are incorporated herein by reference. Background Technology

[0003] As an exhaust gas turbocharger that uses the energy of exhaust gas from an internal combustion engine (engine) to boost the intake air of the engine, a variable capacity type exhaust gas turbocharger with a variable capacity turbine is known (for example, see Patent Document 1). The variable capacity turbine has multiple nozzle blades arranged side-by-side along the circumference of the turbine rotor in the exhaust gas flow path for conveying the exhaust gas from the turbine's vortex flow path to the turbine rotor. By changing the blade angle of these nozzle blades externally using an actuator, the flow path cross-sectional area (the flow path between adjacent nozzle blades) of the exhaust gas flow path can be adjusted. By adjusting the flow path cross-sectional area of ​​the exhaust gas flow path, the variable capacity turbine changes the flow velocity or pressure of the exhaust gas guided to the rotor, thereby improving the boosting effect.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2011-106276 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] However, when the exhaust gas supplied to the variable capacity turbine is at a low flow rate, the cross-sectional area of ​​the exhaust gas flow path is reduced, causing the nozzle blades to be positioned circumferentially along the turbine rotor. Therefore, the inflow angle of the exhaust gas passing between the nozzle blades into the turbine rotor becomes an angle along the aforementioned circumferential direction. If the inflow angle into the turbine rotor at low flow rates is an angle along the aforementioned circumferential direction, a large vortex is generated near the leading edge of the turbine rotor hub, potentially reducing turbine efficiency. It should be noted that Patent Document 1 discloses forming irregularities on the wall defining the exhaust gas flow path to alter the flow of exhaust gas before passing between the nozzle blades, but this does not alter the flow of exhaust gas passing between the nozzle blades.

[0009] In view of the above, the object of at least one embodiment of the present disclosure is to provide a variable capacity turbine capable of improving the efficiency of the turbine at low flow rates and a turbocharger having the variable capacity turbine.

[0010] Technical solutions for solving the problem

[0011] One embodiment of this disclosure provides a variable capacity turbine, which includes:

[0012] Turbine rotor;

[0013] A vortex flow path forming section forms a vortex flow path on the outer peripheral side of the turbine rotor;

[0014] An exhaust gas flow path forming section is formed to guide exhaust gas from the vortex flow path to the turbine rotor;

[0015] A variable nozzle unit, used to adjust the flow of exhaust gas in the exhaust gas flow path, includes a plurality of nozzle blades disposed in the exhaust gas flow path and configured to rotate about their respective centers of rotation.

[0016] The waste gas flow path forming section includes:

[0017] The first plate-shaped component has an annular first plate portion;

[0018] The second plate-shaped component has an annular second plate portion disposed on the turbine outlet side in the axial direction of the turbine rotor compared to the first plate portion, defining the exhaust gas flow path between the second plate portion and the first plate portion.

[0019] The first plate-shaped member has at least one groove extending from the inner periphery to the outer periphery of the first plate on the hub-side flow surface facing the exhaust gas path of the first plate portion.

[0020] One embodiment of this disclosure provides a booster comprising:

[0021] The variable capacity turbine;

[0022] A centrifugal compressor configured to be driven by the variable capacity turbine.

[0023] Invention Effects

[0024] According to at least one embodiment of the present disclosure, a variable capacity turbine capable of improving the efficiency of the turbine at low flow rates and a turbocharger having the variable capacity turbine are provided. Attached Figure Description

[0025] Figure 1 This is a schematic structural diagram that represents the structure of an internal combustion engine system having a turbocharger according to an embodiment of the present disclosure.

[0026] Figure 2 This is a schematic cross-sectional view of the turbine side of a supercharger having a variable capacity turbine according to an embodiment of the present disclosure.

[0027] Figure 3 This is an explanatory diagram illustrating a variable nozzle unit according to one embodiment of the present disclosure.

[0028] Figure 4 This is an explanatory diagram used to illustrate the relationship between the flow rate of exhaust gas supplied to the variable capacity turbine and the efficiency of the turbocharger.

[0029] Figure 5 This is an explanatory diagram illustrating the exhaust gas flow near the trailing edge of the turbine rotor of the variable capacity turbine in the comparative example.

[0030] Figure 6 This is an explanatory diagram illustrating the exhaust gas flow near the turbine rotor of the variable capacity turbine in the comparative example.

[0031] Figure 7 This is a schematic diagram of the exhaust gas flow path of a variable capacity turbine according to one embodiment, viewed from the turbine outlet side in the axial direction. It is a schematic diagram showing the state in which the nozzle blades are open.

[0032] Figure 8 This is a schematic diagram of the exhaust gas flow path of a variable capacity turbine according to one embodiment, viewed from the turbine outlet side in the axial direction. It is a schematic diagram showing the state of the nozzle blades being closed.

[0033] Figure 9 This is an explanatory diagram illustrating the exhaust gas flow near the trailing edge of the turbine rotor of a variable capacity turbine according to one embodiment.

[0034] Figure 10 This is an explanatory diagram illustrating the exhaust gas flow near the turbine rotor of a variable capacity turbine according to one embodiment.

[0035] Figure 11 This is a schematic diagram of the exhaust gas flow path of a variable capacity turbine according to one embodiment, viewed from the turbine outlet side in the axial direction. It is a schematic diagram with the vicinity of the groove enlarged.

[0036] Figure 12 This is a schematic cross-sectional view of a first plate-shaped member in a variable capacity turbine according to one embodiment, taken along the axial direction of the turbine rotor. Detailed Implementation

[0037] Hereinafter, some embodiments of the present disclosure will be described with reference to the accompanying drawings. The dimensions, materials, shapes, and relative arrangements of the constituent parts described in the embodiments or shown in the drawings are not intended to limit the scope of the present disclosure, but are merely illustrative examples.

[0038] For example, expressions such as "in a certain direction", "along a certain direction", "parallel", "orthogonal", "center", "concentric" or "coaxial" indicate relative or absolute configurations, which not only strictly indicate such configurations, but also indicate the state of relative displacement by tolerance or angle or distance to achieve the same function.

[0039] For example, expressions such as "same," "equal," and "homogeneous" that indicate the state of equality of things not only strictly indicate the state of equality, but also indicate the state of difference in the degree to which they have the same function or the existence of a tolerance.

[0040] For example, the expression of shape, such as quadrilateral or cylindrical shape, not only represents the shape in a strict geometric sense, but also represents shapes including concave and convex parts or chamfered parts within the scope of achieving the same effect.

[0041] On the other hand, expressions that "possess," "include," or "have" a constituent element are not exclusive expressions that exclude the existence of other constituent elements.

[0042] It should be noted that there are cases where the same symbols are used to annotate the same structures, but the explanations are omitted.

[0043] (Supercharger)

[0044] Figure 1 This is a schematic structural diagram illustrating the structure of an internal combustion engine system equipped with a turbocharger according to an embodiment of the present disclosure. In the following embodiments, an exhaust gas turbocharger 1A is used as an example for description, but the present disclosure can be applied to turbochargers 1 other than the exhaust gas turbocharger 1A.

[0045] like Figure 1 As shown, in some embodiments, the turbocharger 1 includes an exhaust gas turbocharger 1A configured to compress a fluid (e.g., air) driven by the energy of exhaust gases discharged from the internal combustion engine 10 (engine). Figure 1 As shown, the turbocharger 1 (exhaust gas turbocharger 1A) includes a variable capacity turbine 2 and a centrifugal compressor 3 configured to be driven by the variable capacity turbine 2.

[0046] like Figure 1 As shown, the booster 1 includes a rotating shaft 11, and is disposed on one side of the rotating shaft 11. Figure 1 The turbine rotor 21 (on the right side) is located on the other side of the rotating shaft 11. Figure 1 The impeller 31 (on the left side of the rotor 21), the bearing 12 which supports the rotating shaft 11 so that it can rotate, and the housing 13 which houses them (rotating shaft 11, turbine rotor 21, impeller 31 and bearing 12).

[0047] In the illustrated embodiment, the housing 13 includes a turbine housing 22 configured to house a turbine rotor 21, a compressor housing 32 configured to house an impeller 31, and a bearing housing 14 configured to house a bearing 12. The variable capacity turbine 2 includes the aforementioned turbine rotor 21 and turbine housing 22. The centrifugal compressor 3 includes the aforementioned impeller 31 and compressor housing 32.

[0048] Hereinafter, the direction in which the axis LA of the turbine rotor 21 extends is defined as the axial direction X of the turbine rotor 21, and the direction orthogonal to the axis LA is defined as the radial direction Y. The side of the turbine rotor 21 in the axial direction X that is located relative to the impeller 31 is defined as the turbine side XT, and the side opposite to the turbine side XT, that is, the side of the impeller 31 relative to the turbine rotor 21, is defined as the compressor side XC. In addition, there are cases where the outer side in the radial direction Y is simply represented as the outer circumferential side, and the inner side in the radial direction Y is simply represented as the inner circumferential side.

[0049] The bearing housing 14 is disposed axially between the turbine housing 22 and the compressor housing 32. The bearing 12 is located axially between the turbine rotor 21 and the impeller 31 and is supported by the bearing housing 14. The bearing housing 14 may also be fastened to the turbine housing 22 and the compressor housing 32 respectively by fastening components (e.g., bolts) not shown.

[0050] The compressor housing 32 has a gas inlet 33 for introducing gas into its interior and a gas outlet 34 for discharging gas that has passed through the impeller 31 to the outside. The gas inlet 33 is formed at one end of the booster 1 in the axial direction X (the end of the compressor side XC) and opens toward the compressor side XC.

[0051] Inside the compressor housing 32, a gas inlet path 35 is formed to guide gas introduced from outside the compressor housing 32 through the gas inlet 33 to the impeller 31, and a vortex-shaped flow path 37 is formed to discharge gas that has passed through the impeller 31 to the outside through the gas outlet 34. The gas inlet path 35 extends along the axial direction X. The vortex flow path 37 is formed on the outer peripheral side of the impeller 31.

[0052] The compressor housing 32 has a gas inlet forming section 36 that forms a gas inlet passage 35 and a vortex flow path forming section 38 that forms a vortex flow path 37. A gas inlet 33 is formed at the upstream end of the gas inlet forming section 36, and a gas outlet 34 is formed at the downstream end of the vortex flow path forming section 38. The impeller 31 is configured to guide gas introduced from the compressor side XC along the axial direction X to the outer side in the radial direction Y.

[0053] The turbine housing 22 has an exhaust gas inlet 23 for introducing exhaust gas into its interior and an exhaust gas outlet 24 for discharging exhaust gas that has passed through the turbine rotor 21 to the outside. The exhaust gas outlet 24 is formed at the other end of the turbocharger 1 in the axial direction X (the end of the turbine side XT) and opens toward the turbine side XT.

[0054] Inside the turbine housing 22, there is a vortex-shaped flow path 25 for guiding exhaust gas introduced from outside the turbine housing 22 through the exhaust gas inlet 23 toward the turbine rotor 21, and an exhaust gas discharge path 27 for discharging the exhaust gas that has passed through the turbine rotor 21 to the outside through the exhaust gas outlet 24. The exhaust gas discharge path 27 extends along the axial direction X. The vortex flow path 25 is formed on the outer peripheral side of the turbine rotor 21.

[0055] The turbine housing 22 has a vortex flow path forming portion 26 that forms a vortex flow path 25 and an exhaust gas discharge path forming portion 28 that forms an exhaust gas discharge path 27. An exhaust gas outlet 24 is formed at the downstream end of the exhaust gas discharge path forming portion 28. The turbine rotor 21 is configured to guide exhaust gas introduced from the outer side in the radial direction Y along the axial direction X towards the turbine side XT.

[0056] The turbocharger 1 includes a gas line 15 for guiding gas from the centrifugal compressor 3 to the internal combustion engine 10 and an exhaust gas line 16 for guiding exhaust gas from the internal combustion engine 10 to the variable capacity turbine 2. The gas line 15 includes a pipe 151, one side of which is connected to the internal combustion engine 10, and the other side of which is connected to the gas outlet 34 of the centrifugal compressor 3. The exhaust gas line 16 includes a pipe 161, one side of which is connected to the internal combustion engine 10, and the other side of which is connected to the exhaust gas inlet 23 of the variable capacity turbine 2.

[0057] Gas passing through the impeller 31 and vortex flow path 37 of the centrifugal compressor 3 is guided to the internal combustion engine 10 (engine) via the gas pipeline 15 for combustion in the internal combustion engine 10. Exhaust gas generated by combustion in the internal combustion engine 10 passes through the exhaust gas pipeline 16 and is guided to the turbine rotor 21 via the vortex flow path 25 of the variable capacity turbine 2.

[0058] The turbocharger 1 is configured to rotate the turbine rotor 21 using the energy from the exhaust gas discharged from the internal combustion engine 10. The impeller 31 is mechanically connected to the turbine rotor 21 via a rotating shaft 11, and therefore rotates in conjunction with the rotation of the turbine rotor 21. The turbocharger 1 is configured to compress the gas passing through the impeller 31 by the rotation of the impeller 31, increasing the density of the gas and delivering it to the internal combustion engine 10.

[0059] (Variable capacity turbine)

[0060] Figure 2 This is a schematic cross-sectional view of the turbine side of a supercharger equipped with a variable capacity turbine according to an embodiment of the present disclosure. Figure 2 In the diagram, the supercharger 1 is schematically represented by a cross section along the axis LA of the rotation shaft 11.

[0061] like Figure 2As shown, the variable capacity turbine 2 includes the aforementioned turbine rotor 21, the aforementioned vortex flow path forming portion 26 forming a vortex flow path 25 on the outer periphery of the turbine rotor 21, the aforementioned exhaust flow path forming portion 4 forming an exhaust flow path (nozzle flow path) 40 for guiding exhaust gas from the vortex flow path 25 to the turbine rotor 21, and a variable nozzle unit 5 for adjusting the flow of exhaust gas in the exhaust flow path 40. The exhaust flow path 40 is formed between the vortex flow path 25 and the turbine rotor 21 in a manner that surrounds the turbine rotor 21 (outer side in the radial Y direction).

[0062] like Figure 2 As shown, the turbine rotor 21 includes a hub 211 and a plurality of blades 212 disposed on the outer surface of the hub 211. The turbine rotor 21 is configured to guide exhaust gas introduced radially from the outside toward the turbine outlet side (turbine side XT) in the axial direction X.

[0063] (Exhaust gas flow path formation section)

[0064] like Figure 2 As shown, the exhaust gas flow path forming section 4 includes a first plate-shaped member (nozzle seat) 41 fixed to the housing 13, and a second plate-shaped member (nozzle plate) 42 disposed on the turbine outlet side (turbine side XT) in the axial direction X compared to the first plate-shaped member 41 and defining the exhaust gas flow path 40 between the first plate-shaped member 41 and the turbine side XT. Hereinafter, the compressor side XC in the exhaust gas flow path 40 may be referred to as the hub side, and the turbine side XT in the exhaust gas flow path 40 may be referred to as the shield side.

[0065] The first plate-shaped member 41 includes an annular first plate portion 43 extending circumferentially along the outer periphery of the turbine rotor 21. The first plate-shaped member 41 has a hub-side flow surface 44 formed on the turbine side XT of the first plate portion 43. In the illustrated embodiment, the first plate-shaped member 41 is fixed to the housing 13 by clamping the outer peripheral edge of the first plate portion 43 between the turbine housing 22 and the bearing housing 14.

[0066] The second plate-shaped member 42 includes an annular second plate portion 45 extending circumferentially along the outer periphery of the turbine rotor 21, and a protrusion 46 protruding axially from the inner periphery of the second plate portion 45 toward the turbine side XT. The second plate-shaped member 42 has a shroud-side flow surface 47 formed on the compressor side XC of the second plate portion 45, and a shroud surface 48 connected to the shroud-side flow surface 47 and curved into a convex shape. The shroud surface 48 is formed on the inner periphery of the second plate portion 45, forming a gap (clearance) between the blade tips of the turbine rotor 21.

[0067] The exhaust gas flow path 40 is defined between the hub side flow path 44 and the shield side flow path 47. The hub side flow path 44 and the shield side flow path 47 extend in a direction that intersects (e.g., orthogonally) the axis LA of the rotation axis 11. The shield side flow path 47 is located on the turbine side XT, opposite to the hub side flow path 44.

[0068] The exhaust gas flow path forming section 4 may further include at least one nozzle support 49 that supports the first plate-shaped member 41 and the second plate-shaped member 42 in a mutually separated state. One side of the at least one nozzle support 49 is fixed to the first plate portion 43 of the first plate-shaped member 41, and the other side is fixed to the second plate portion 45 of the second plate-shaped member 42. The second plate-shaped member 42 is supported separately from the first plate-shaped member 41 along the axial direction X by the at least one nozzle support 49. In the illustrated embodiment, the at least one nozzle support 49 includes a plurality of nozzle supports 49 arranged at intervals along the circumference of the turbine rotor 21. That is, the exhaust gas flow path forming section 4 includes a plurality of nozzle supports 49.

[0069] The exhaust gas introduced into the turbine housing 22 passes through the vortex flow path 25, then through the exhaust gas flow path 40, and is guided to the turbine rotor 21, causing the turbine rotor 21 to rotate. After passing through the turbine rotor 21, the exhaust gas passes through the exhaust gas discharge path 27 and is discharged from the exhaust gas discharge outlet 24 to the outside of the turbine housing 22.

[0070] (Variable nozzle unit)

[0071] like Figure 2 As shown, the variable nozzle unit 5 includes a plurality of nozzle blades 6 arranged at intervals along the circumference of the turbine rotor 21 in the aforementioned exhaust gas flow path 40, and a rotation mechanism 51 configured to rotate the plurality of nozzle blades 6 about their respective rotation centers RC. The variable nozzle unit 5 changes the blade angle of the plurality of nozzle blades arranged in the exhaust gas flow path 40 by means of the rotation mechanism 51, thereby adjusting the flow path cross-sectional area of ​​the exhaust gas flow path 40. The variable capacity turbine 2 can change the flow velocity or pressure of the exhaust gas guided to the turbine rotor 21 by increasing or decreasing the flow path cross-sectional area of ​​the exhaust gas flow path 40 by means of the variable nozzle unit 5, thereby controlling the boost pressure of the variable capacity turbine 2.

[0072] like Figure 2 As shown, the plurality of nozzle blades 6 each have a hub-side end 61 with a gap (clearance) between it and the hub-side flow surface 44, and a shield-side end 62 with a gap (clearance) between it and the shield-side flow surface 47.

[0073] like Figure 2As shown, the rotating mechanism 51 includes an annular drive ring 52 configured to rotate circumferentially relative to the first plate-shaped member 41 along the turbine rotor 21, a plurality of blade shafts 53, a plurality of rod plates 54, an actuator 55 configured to rotate the drive ring 52 about its axis LC, and a controller 57 (control device) configured to control the drive (i.e., the amount of movement in the circumferential direction about the axis LC) of the drive shaft 56 of the actuator 55.

[0074] Figure 3 This is an explanatory diagram illustrating a variable nozzle unit according to one embodiment of the present disclosure. Figure 3 In the figure, the variable nozzle unit 5 is schematically represented as viewed from the compressor side XC along the axial direction X.

[0075] like Figure 3 As shown, the rotating mechanism 51 includes blade shafts 53 and rod plates 54 in the same number as the nozzle blades 6 included in the variable nozzle unit 5. One side of the blade shaft 53 is fixed to the nozzle blade 6, and the other side is mechanically connected to one side of the rod plate 54. The other side of the rod plate 54 is mechanically connected to the drive ring 52. The actuator 55 includes an electric motor or cylinder, etc. The drive shaft 56 of the actuator 55 is mechanically connected to the drive ring 52.

[0076] Each of the multiple rod plates 54 includes a fitting portion 541 that fits into the fitting portion 521 formed on the drive ring 52. The fitting portion 521 includes a groove portion 522 formed on the outer periphery of the drive ring 52, and the fitting portion 541 is configured to be received inside the groove portion 522 and loosely fitted into the groove portion 522.

[0077] like Figure 3 As shown, the first plate-shaped member 41 has a plurality of through holes 411 formed at circumferentially spaced apart positions along the axis LA. The number of through holes 411 formed on the first plate-shaped member 41 is the same as the number of nozzle blades 6 included in the variable nozzle unit 5. The plurality of blade shafts 53 are rotatably inserted into one of the plurality of through holes 411.

[0078] like Figure 2 As shown, an annular internal space 17 is formed inside the back surface 412 of the first plate-shaped member 41 located on the opposite side (compressor side XC) of the hub-side flow surface 44 of the first plate portion 43 and the annular groove 141 formed on the turbine side XT of the bearing housing 14. The drive ring 52 and a plurality of rod plates 54 are accommodated in the aforementioned internal space 17 formed inside the housing 13.

[0079] In the power transmission path from the actuator 55 to the plurality of nozzle blades 6, the drive shaft 56 and the drive ring 52, the drive ring 52 and the rod plate 54, and the rod plate 54 and the blade shaft 53 are respectively connected to each other. If the actuator 55 is driven by the controller 57, the drive ring 52 rotates about the axis LC as the drive shaft 56 of the actuator 55 moves. If the drive ring 52 rotates, the plurality of nozzle blades 6 rotate about their respective rotation centers RC in conjunction with the rotation of the drive ring 52 via the rod plate 54 and the blade shaft 53, thereby changing their blade angle.

[0080] If the drive ring 52 is rotated to one side of the turbine rotor 21 in the circumferential direction, the adjacent nozzle blades 6 in the aforementioned circumferential direction move away from each other, and the cross-sectional area of ​​the exhaust gas path 40 between the nozzle blades 6 increases. Conversely, if the drive ring 52 is rotated to the other side of the turbine rotor 21 in the circumferential direction, the adjacent nozzle blades 6 in the aforementioned circumferential direction move closer to each other, and the cross-sectional area of ​​the exhaust gas path 40 between the nozzle blades 6 decreases.

[0081] Figure 4 This is an explanatory diagram illustrating the relationship between the flow rate of exhaust gas supplied to the variable capacity turbine and the efficiency of the turbocharger. Figure 4 In the graph, a curve C1 showing the relationship between the exhaust gas flow rate and the turbocharger 1 is shown, with the exhaust gas flow rate supplied to the variable capacity turbine 2 as the horizontal axis and the turbocharger 1 efficiency as the vertical axis. A schematic diagram showing the opening and closing states between the nozzle blades 6 when the exhaust gas flow rate supplied to the variable capacity turbine 2 is low, at the efficiency peak, and at a high flow rate higher than the efficiency peak is also shown.

[0082] Supercharger 1 Figure 4 As shown, the turbocharger 1 is configured such that its efficiency peaks when the exhaust gas supplied to the variable capacity turbine 2 is at a high flow rate. The variable capacity turbine 2 is as follows... Figure 4 As shown, when the flow rate of exhaust gas supplied to the variable capacity turbine 2 is low, compared to the high flow rate, the adjacent nozzle blades 6 in the circumferential direction of the turbine rotor 21 move closer to each other, and the cross-sectional area of ​​the exhaust gas flow path 40 becomes smaller. At this low flow rate, the nozzle blades 6 are positioned along the aforementioned circumferential direction; therefore, the inflow angle of the exhaust gas passing between the nozzle blades 6 into the turbine rotor 21 becomes an angle along the aforementioned circumferential direction. It should be noted that the inflow angle into the turbine rotor 21 is not uniform in the blade width direction; compared to the central portion in the blade width direction, the inflow angle changes on the hub side or shroud side due to the clearance formed thereon.

[0083] Figure 5 This is an explanatory diagram illustrating the exhaust gas flow near the trailing edge of the turbine rotor of the variable capacity turbine in the comparative example. Figure 6This is an explanatory diagram illustrating the exhaust gas flow near the turbine rotor of the variable capacity turbine in the comparative example.

[0084] In the comparative example, the hub-side flow surface 44 of the variable-capacity turbine 2 does not form the groove 7 described later, but is flat across the entire surface. In this case, at low flow rates, the inflow angle of the exhaust gas to the turbine rotor 21 becomes an angle along the aforementioned circumferential direction; therefore, as... Figure 5 As shown, there is a possibility of generating large vortices V near the outer surface of the hub 211 on the leading edge 213 side of the turbine rotor 21. Figure 6 As shown, the large vortex V flows along the outer surface of the hub 211 toward the trailing edge 214 of the turbine rotor 21. Therefore, the flow loss caused by the vortex V is generated throughout the entire area of ​​the turbine rotor 21 from the leading edge 213 to the trailing edge 214, which may reduce the efficiency of the variable capacity turbine 2.

[0085] Figure 7 and Figure 8 These are schematic diagrams showing the exhaust gas flow path of a variable capacity turbine according to one embodiment, viewed from the axial turbine outlet side. Figure 7 This indicates the state in which the nozzle blades are open at high flow rates. Figure 8 This is a schematic diagram showing the nozzle blades closed at low flow rates. It should be noted that, as... Figure 8 As shown, when the nozzle blades 6 are closed, a gap is formed between adjacent nozzle blades 6 in the circumferential direction of the turbine rotor 21, through which exhaust gas passes.

[0086] like Figure 7 , Figure 8 As shown, the first plate-shaped member 41 has at least one groove 7 extending from the inner periphery 431 of the first plate portion 43 to the outer periphery on the hub-side flow surface 44 facing the exhaust gas passage 40. In the illustrated embodiment, the same number of grooves 7 as nozzle blades 6 are formed on the hub-side flow surface 44. For each of the plurality of grooves 7, at least a portion is located between the rotation centers RC of adjacent nozzle blades 6 in the circumferential direction of the turbine rotor 21. In addition, the outer peripheral ends 74 of each of the plurality of grooves 7 are located radially inward compared to the aforementioned rotation centers RC.

[0087] like Figure 2 As shown, some embodiments of the variable capacity turbine 2 include the turbine rotor 21 described above, a vortex flow path forming section 26 forming the vortex flow path 25 described above, an exhaust flow path forming section 4 forming the exhaust flow path 40 described above, and a variable nozzle unit 5 including the plurality of nozzle blades 6 described above. Figure 2 As shown, the exhaust gas flow path forming section 4 includes a first plate-shaped member 41 having the aforementioned annular first plate portion 43, and a second plate-shaped member 42 having the aforementioned annular second plate portion 45. Figure 7 , Figure 8 As shown, the first plate-shaped member 41 has at least one groove 7 extending from the inner periphery 431 of the first plate portion 43 to the outer periphery on the hub side flow surface 44 facing the exhaust flow path 40.

[0088] According to the above structure, the groove 7 formed on the hub-side flow path 44 extends from the inner periphery 431 of the first plate 43 to the outer periphery, thus guiding the exhaust gas flowing into the groove 7 directly to the turbine rotor 21. The exhaust gas flowing in the groove 7 is guided by the wall surface (first wall surface 71) of the groove 7, and the inflow angle to the turbine rotor 21 is corrected to an angle along the wall surface. Therefore, at low flow rates, the inflow angle (inclination angle relative to the radial direction) of the exhaust gas flowing on the hub side to the leading edge 213 of the turbine rotor 21 can be maintained at a predetermined angle (fixed value α).

[0089] Figure 9 This is an explanatory diagram illustrating the exhaust gas flow near the trailing edge of the turbine rotor of a variable capacity turbine according to one embodiment. Figure 10 This is an explanatory diagram illustrating the exhaust gas flow near the turbine rotor of a variable capacity turbine according to one embodiment.

[0090] By utilizing the aforementioned groove 7, the inflow angle at low flow rates is maintained at a predetermined angle (fixed value α), such as... Figure 9 As shown, it is possible to reduce the vortex V generated near the leading edge 213 side of the hub 211 of the turbine rotor 21 at low flow rates. By reducing the aforementioned vortex V, as... Figure 10 As shown, it can suppress the turbulence of exhaust gas flow near the hub 211 of the turbine rotor 21, and thus reduce the losses of the turbine rotor 21 caused by the eddy V. As a result, the efficiency of the turbine 2 at low flow rates can be improved.

[0091] Figure 11 This is a schematic diagram of the exhaust gas flow path of a variable capacity turbine according to one embodiment, viewed from the turbine outlet side in the axial direction. It is a schematic diagram with the vicinity of the groove enlarged.

[0092] like Figure 11 As shown, the plurality of nozzle blades 6 include an upstream nozzle blade 6A adjacent to one of the plurality of slots 7 on the upstream side of the turbine rotor 21 in the rotation direction RD, and a downstream nozzle blade 6B adjacent to the aforementioned slot 7 on the downstream side of the turbine rotor 21 in the rotation direction RD. The plurality of slots 7 each include a first wall surface 71 and a second wall surface 72 extending from the hub-side flow surface 44 of the first plate portion 43 toward the opposite back surface 412, and a third wall surface (bottom surface) 73 connecting the first wall surface 71 and the second wall surface 72.

[0093] In some implementations, such as Figure 11As shown, at least one of the groove portions 7 described above includes a first wall 71 that connects the outer peripheral end 74 of the groove portion 7 to the downstream end 711 on the inner peripheral edge 431 of the groove portion 7 located downstream of the outer peripheral end 74 in the rotation direction RD of the turbine rotor 21.

[0094] According to the above structure, the exhaust gas flowing in the slot 7 is guided by the first wall 71 and corrected to an angle along the first wall 71. Using the first wall 71, the inflow angle (the tilt angle relative to the radial direction of the turbine rotor 21) of the exhaust gas flowing on the hub side towards the leading edge 213 of the turbine rotor 21 can be maintained at a predetermined angle (fixed value α) even at low flow rates. Because the first wall 71 connects the outer peripheral end 74 of the slot 7 to the downstream end 711 on the inner peripheral edge 431 of the slot 7, it can correct the flow direction of the exhaust gas without obstructing the flow of the exhaust gas within the slot 7.

[0095] In some implementations, such as Figure 11 As shown, the first wall surface 71 includes a convex surface 71A. In a top view orthogonal to the axis LA of the turbine rotor 21, the convex surface 71A protrudes downstream in the rotation direction RD relative to the imaginary line IL that connects the outer peripheral end 74 and the downstream end 711 on the inner peripheral edge 431 of the groove 7 in a straight line.

[0096] According to the above structure, the first wall surface 71 includes a convex curved surface 71A protruding downstream of the rotation direction RD of the turbine rotor 21, thus enabling the smooth guidance of the exhaust gas flowing within the slot 7. Consequently, since the stripping of exhaust gas from the first wall surface 71 can be suppressed, the flow direction of the exhaust gas can be corrected using the first wall surface 71 without obstructing the flow of the exhaust gas.

[0097] In some implementations, such as Figure 11 As shown, the aforementioned convex surface 71A is inclined such that, in a top view orthogonal to the axis LA of the turbine rotor 21, the tangent TL of the convex surface 71A is inclined at an angle β relative to the radial direction of the turbine rotor 21, decreasing towards the downstream end 711. The inclination angle β becomes the minimum angle α at the downstream end 711. The inflow angle of the exhaust gas flowing along the convex surface 71A into the turbine rotor 21 is also the aforementioned angle α.

[0098] According to the above structure, the convex surface 71A is tilted such that the tilt angle β of the tangent TL of the convex surface 71A relative to the radial direction of the turbine rotor 21 decreases as it moves toward the downstream end 711 in a top view orthogonal to the axis LA of the turbine rotor 21. Therefore, it is possible to suppress the stripping of exhaust gas from the convex surface 71A, while correcting the inflow angle (relative to the radial tilt angle) of the exhaust gas flowing along the convex surface 71A toward the turbine rotor 21 to a small angle.

[0099] In some implementations, such as Figure 11 As shown, the aforementioned plurality of nozzle blades 6 include a downstream nozzle blade 6B adjacent to at least one groove 7 on the downstream side of the turbine rotor 21 in the rotation direction RD. The hub-side flow surface 44 of the aforementioned first plate-shaped member 41 has a region A1 in which, in a top view orthogonal to the axis LA of the turbine rotor 21, the groove 7 is not formed between the first wall surface 71 of the groove 7 in the rotation direction RD of the turbine rotor 21 and the rotation region RA1 of the downstream nozzle blade 6B. The rotation region RA1 of the downstream nozzle blade 6B is in the state where the downstream nozzle blade 6B is open (see reference). Figure 7 ) to the closed state (refer to) Figure 8 There exists a range of downstream nozzle blades 6B that is projected onto the hub-side flow path 44 of the first plate portion 43 in the above top view. No groove 7 is formed in this rotational region RA1.

[0100] According to the above structure, the hub-side flow path 44 has a region A1 where no groove 7 is formed between the first wall surface 71 and the rotation area RA1 of the downstream nozzle blade 6B. Therefore, the groove 7 can be used to suppress the increase of the clearance between the hub-side flow path 44 and the hub-side end 61 of the downstream nozzle blade 6B, and the increase of exhaust gas flow loss caused by the increase of this clearance can be suppressed. In addition, by having a region A1 where no groove 7 is formed between the first wall surface 71 and the rotation area RA1 of the downstream nozzle blade 6B, the degree of freedom in setting the shape of the first wall surface 71 can be increased.

[0101] In some implementations, such as Figure 11 As shown, at least one of the aforementioned groove portions 7 further includes a second wall surface 72, which connects the outer peripheral end 74 of the groove portion 7 to an upstream end 721 located on the inner peripheral edge 431 of the groove portion 7 upstream of the outer peripheral end 74 in the rotational direction RD of the turbine rotor 21. In the illustrated embodiment, the second wall surface 72 connects the outer peripheral end 74 and the upstream end 721 in a straight line in a top view orthogonal to the axis LA of the turbine rotor 21, but it may also connect the outer peripheral end 74 and the upstream end 721 in a curved line.

[0102] According to the above structure, the groove 7 includes a first wall surface 71 connecting the outer peripheral end 74 of the groove 7 to the downstream end 711 on the inner peripheral edge 431 of the groove 7, and a second wall surface 72 connecting the outer peripheral end 74 of the groove 7 to the upstream end 721 on the inner peripheral edge 431 of the groove 7. In this case, the area (projected area) of the groove 7 in a top view orthogonal to the axis LA of the turbine rotor 21 can be increased, thus allowing a large amount of exhaust gas to flow into the groove 7. In this case, the flow direction of the large amount of exhaust gas in the groove 7 can be corrected by using the groove 7, thus effectively correcting the flow of exhaust gas flowing on the hub side at low flow rates.

[0103] In some implementations, such as Figure 11 As shown, the aforementioned plurality of nozzle blades 6 include an upstream-side nozzle blade 6A adjacent to at least one groove 7 on the upstream side of the turbine rotor 21 in the rotation direction RD. The hub-side flow path 44 of the aforementioned first plate-shaped member 41 has a region A2, which, in a top view orthogonal to the axis LA of the turbine rotor 21, does not have a groove 7 formed between the second wall 72 of the groove 7 in the rotation direction RD of the turbine rotor 21 and the rotation region RA2 of the upstream-side nozzle blade 6A. The rotation region RA2 of the upstream-side nozzle blade 6A is in the state where the upstream-side nozzle blade 6A is open (see reference). Figure 7 ) to the closed state (refer to) Figure 8 There exists a region between the upstream nozzle blades 6A that is projected onto the hub-side flow path 44 of the first plate portion 43 in the above top view. No groove 7 is formed in this rotational region RA2.

[0104] According to the above structure, the hub side flow road surface 44 has a region A2 between the second wall surface 72 and the rotation area RA2 of the upstream nozzle blade 6A where the groove 7 is not formed. Therefore, the groove 7 can be used to suppress the increase of the clearance between the hub side flow road surface 44 and the hub side end 61 of the upstream nozzle blade 6A, and the increase of exhaust gas flow loss caused by the increase of the clearance can be suppressed.

[0105] Figure 12 This is a schematic cross-sectional view, representing a section along the axial direction of the turbine rotor, of the first plate-shaped member in a variable capacity turbine according to one embodiment. Figure 12 The diagram schematically shows the first plate-shaped component 41 viewed from the upstream side in the rotation direction RD. Figure 7 The state of section A-B is shown. Additionally, in Figure 12 The middle is represented by a dashed line. Figure 7 The shape of the groove 7 on the C-D cross section shown.

[0106] In some implementations, such as Figure 12As shown, the aforementioned hub side flow surface 44 includes a flat surface 44A extending radially along the turbine rotor 21. The aforementioned at least one groove 7 is configured such that its depth from the flat surface 44A increases as it approaches the inner circumferential side of the first plate portion 43.

[0107] According to the above structure, by configuring the groove 7 such that its depth from the flat surface 44A increases towards the inner circumference of the first plate 43, exhaust gas flowing along the flat surface 44A can easily flow into the groove 7. Furthermore, the wall surface (third wall surface 73) of the groove 7 can be used to gently guide the exhaust gas flowing within the groove 7 towards the inner circumference and direct it towards the turbine rotor 21. Therefore, because turbulence in the flow of exhaust gas flowing at the hub side or within the groove 7 can be suppressed at low flow rates, the efficiency reduction of the turbine 2 at low flow rates can be suppressed.

[0108] In some embodiments, for at least one groove 7 described above, such as Figure 12 As shown, the inclined surface 73A extends in a direction intersecting the flat surface 44A in a top view along the axis LA of the turbine rotor 21, and the inclined angle θ relative to the imaginary extended surface 44B that extends the flat surface 44A satisfies the condition 0° < θ < 15°.

[0109] According to the above structure, if the inclination angle θ of the inclined surface 73A relative to the imaginary extended surface 44B is too large, exhaust gas will be stripped from the inclined surface 73A, and the inclined surface 73A may not be able to guide the exhaust gas. By making the inclination angle θ of the inclined surface 73A satisfy the above condition, the stripping of exhaust gas from the inclined surface 73A can be suppressed. Therefore, the inclined surface 73A can be used to guide the exhaust gas flowing in the groove 7 to the inner circumference.

[0110] In some implementations, such as Figure 12 As shown, the hub-side flow path 44 includes a flat surface 44A extending radially along the turbine rotor 21. The at least one groove 7 is configured such that, with the wall thickness of the first plate portion 43 set to T and the maximum depth of the at least one groove 7 from the flat surface 44A set to T1, the condition 0 < T1 ≤ 0.2T is satisfied. The groove 7 has its maximum depth from the flat surface 44A at its inner periphery 431. If the groove 7 is too deep (i.e., the maximum depth T1 is too large), the flow towards the back of the turbine rotor 21 increases, potentially causing a change in the thrust acting on the turbine rotor 21. Furthermore, if the groove 7 is too deep, the mainstream flow within the exhaust gas path 40 is obstructed, potentially increasing exhaust gas flow losses. The groove 7 is preferably configured to satisfy the condition 0 < T1 ≤ 0.1T.

[0111] According to the above structure, if the maximum depth T1 of the groove 7 from the flat surface 44A is too large, the inflow of exhaust gas into the groove 7 will increase, the mainstream flow in the exhaust gas flow path 40 will be obstructed, and there is a possibility of increased exhaust gas flow loss. By configuring the groove 7 to satisfy the above conditions with the maximum depth T1, the obstruction of the mainstream flow in the exhaust gas flow path 40 can be suppressed, and the efficiency reduction of the turbine 2 can be suppressed.

[0112] like Figure 1 As shown, in some embodiments, the turbocharger 1 includes the aforementioned variable capacity turbine 2 and a centrifugal compressor 3 driven by the variable capacity turbine 2. In this case, the eddy current V generated near the leading edge 213 side of the hub 211 of the turbine rotor 21 at low flow rates can be reduced, thus improving the efficiency of the variable capacity turbine 2 and the turbocharger 1 equipped with the variable capacity turbine 2 at low flow rates.

[0113] This disclosure is not limited to the above-described embodiments, but also includes modifications to the above-described embodiments and appropriate combinations of these modifications.

[0114] The contents described in some of the above-described embodiments can be understood as follows.

[0115] 1) At least one embodiment of this disclosure relates to a variable capacity turbine (2), which comprises:

[0116] Turbine rotor (21);

[0117] A vortex flow path forming section (26) forms a vortex flow path (25) on the outer periphery of the turbine rotor (21);

[0118] Exhaust gas flow path forming section (4) forms an exhaust gas flow path (40) for guiding exhaust gas from the vortex flow path (25) to the turbine rotor (21);

[0119] A variable nozzle unit (5), used to adjust the flow of the exhaust gas in the exhaust gas flow path (40), includes a plurality of nozzle blades (6) disposed in the exhaust gas flow path (40) and configured to rotate about their respective rotation centers.

[0120] The waste gas flow path forming section (4) includes:

[0121] The first plate-shaped component (41) has an annular first plate portion (43);

[0122] The second plate-shaped component (42) has an annular second plate portion (45) disposed on the turbine outlet side of the turbine rotor (21) in axial direction compared with the first plate portion (43), defining the exhaust gas flow path (40) between the second plate portion (45) and the first plate portion (43).

[0123] For the first plate-shaped member (41), at least one groove (7) extending from the inner periphery (431) to the outer periphery is formed on the hub side flow surface (44) of the first plate portion (43) facing the exhaust flow path (40).

[0124] According to the structure described in 1), the groove (7) formed on the hub-side flow path (44) extends from the inner periphery (431) of the first plate (43) to the outer periphery, thus allowing the exhaust gas flowing into the groove (7) to be guided directly from the groove (7) to the turbine rotor (21). The exhaust gas flowing in the groove (7) is guided by the wall (first wall 71) of the groove (7), correcting the inflow angle to the turbine rotor (21) to an angle along the wall. As a result, at low flow rates, the inflow angle (the angle of inclination relative to the radial direction) of the exhaust gas flowing on the hub side to the leading edge (213) of the turbine rotor (21) can be maintained at a predetermined angle (fixed value α). By maintaining the inflow angle at the predetermined angle, the vortices generated near the leading edge (213) of the hub (211) of the turbine rotor (21) can be reduced at low flow rates. By reducing the aforementioned eddies, the losses of the turbine rotor (21) caused by the eddies can be reduced, thus improving the efficiency of the turbine (2) at low flow rates.

[0125] 2) In some embodiments, according to the variable capacity turbine (2) described in 1) above, wherein,

[0126] The at least one groove (7) includes a first wall (71) that connects the outer peripheral end (74) of the groove (7) to the downstream end (711) of the groove (7) located on the inner peripheral edge (431) of the groove (7) on the downstream side of the rotation direction of the turbine rotor (21) relative to the outer peripheral end (74).

[0127] According to the structure described in 2), the exhaust gas flowing in the slot (7) is guided towards the first wall (71) and corrected to an angle along the first wall (71). Using the first wall (71), the inflow angle (the angle of inclination relative to the radial direction) of the exhaust gas flowing on the hub side towards the leading edge (213) of the turbine rotor (21) can be maintained at a predetermined angle (fixed value α) at ​​low flow rates. The first wall (71) connects the outer peripheral end (74) of the slot (7) and the downstream end (711) on the inner peripheral edge (431) of the slot (7), thus, the flow direction of the exhaust gas can be corrected without obstructing the flow of the exhaust gas flowing in the slot (7).

[0128] 3) In some embodiments, according to the variable capacity turbine (2) described in 2) above, wherein,

[0129] The first wall surface (71) includes a convex surface (71A) which, in a top view orthogonal to the axis of the turbine rotor (21), protrudes downstream in the rotational direction relative to an imaginary line (IL) connecting the outer peripheral end (74) of the groove (7) and the downstream end (711) on the inner peripheral edge (431) in a straight line.

[0130] According to the structure described in 3), the first wall (71) includes a convex curved surface (71A) protruding downstream in the rotational direction of the turbine rotor (21), thus allowing the exhaust gas flowing within the slot (7) to be smoothly guided. Therefore, since the stripping of exhaust gas from the first wall (71) can be suppressed, the flow direction of the exhaust gas can be corrected using the first wall (71) without obstructing the flow of the exhaust gas.

[0131] 4) In some embodiments, according to the variable capacity turbine (2) described in 3) above, wherein,

[0132] The convex surface (71A) is tilted in such a way that the tangent (TL) of the convex surface (71A) in a top view orthogonal to the axis of the turbine rotor (21) is tilted relative to the radial direction of the turbine rotor (21) at an angle that decreases toward the downstream end (711).

[0133] According to the structure described in 4), the convex surface (71A) is inclined such that the tangent (TL) of the convex surface (71A) in a top view orthogonal to the axis of the turbine rotor (21) has a smaller inclination angle relative to the radial direction of the turbine rotor (21) as it moves toward the downstream end. Therefore, it is possible to suppress the stripping of exhaust gas from the convex surface (71A) and correct the inflow angle (relative to the radial inclination angle) of the exhaust gas flowing along the convex surface (71A) to the turbine rotor (21) to a small angle.

[0134] 5) In some embodiments, the variable capacity turbine (2) is as described in any one of 2) to 4) above, wherein,

[0135] The plurality of nozzle blades (6) are included in the downstream nozzle blades (6B) adjacent to the at least one slot (7) on the downstream side of the rotation direction of the turbine rotor (21).

[0136] The hub-side flow surface (44) of the first plate-shaped component (41) has a region (A1) which, in a top view orthogonal to the axis of the turbine rotor (21), is the region (A1) between the first wall surface (71) of the groove (7) in the rotation direction of the turbine rotor (21) and the rotation area (RA1) of the downstream nozzle blade (6B) where the groove (7) is not formed.

[0137] According to the structure described in 5), the hub side flow road surface (44) has a region (A1) where no groove (7) is formed between the first wall surface (71) and the rotation area (RA1) of the downstream nozzle blade (6B). Therefore, the groove (7) can be used to suppress the increase of the clearance between the hub side flow road surface (44) and the hub side end (61) of the downstream nozzle blade (6B), and the increase of exhaust gas flow loss caused by the increase of the clearance can be suppressed. In addition, for the hub side flow road surface (44), by having a region (A1) where no groove (7) is formed between the first wall surface (71) and the rotation area (RA1) of the downstream nozzle blade (6B), the rotation area (RA1) of the downstream nozzle blade (6B) can be disregarded when setting the shape of the first wall surface (71). Therefore, the degree of freedom of the shape of the first wall surface (71) can be improved.

[0138] 6) In some embodiments, the variable capacity turbine (2) is as described in any one of 2) to 5) above, wherein,

[0139] The at least one groove (7) further includes a second wall (72) that connects the outer peripheral end (74) of the groove (7) to the upstream end (721) on the inner peripheral edge (431) of the groove (7) located upstream of the outer peripheral end (74) in the rotation direction of the turbine rotor (21).

[0140] According to the structure described in 6), the groove (7) includes a first wall (71) connecting the outer peripheral end (74) of the groove (7) to the downstream end (711) on the inner peripheral edge (431) of the groove (7), and a second wall (72) connecting the outer peripheral end (74) of the groove (7) to the upstream end (721) on the inner peripheral edge (431) of the groove (7). In this case, the area (projected area) of the groove (7) in plan view orthogonal to the axis of the turbine rotor (21) can be increased, thus allowing a large amount of exhaust gas to flow into the groove (7). In this case, the flow direction of a large amount of exhaust gas in the groove (7) can be corrected by using the groove (7), thus effectively correcting the flow of exhaust gas flowing on the hub side at low flow rates.

[0141] 7) In some embodiments, according to the variable capacity turbine (2) described in 6) above, wherein,

[0142] The plurality of nozzle blades (6) are included in the upstream nozzle blade (6A) adjacent to the at least one slot (7) on the upstream side of the rotation direction of the turbine rotor (21).

[0143] The hub-side flow surface (44) of the first plate-shaped component (41) has a region (A2) in which, in a top view orthogonal to the axis of the turbine rotor (21), the groove (7) is not formed between the second wall surface (72) of the groove (7) in the direction of rotation of the turbine rotor (21) and the rotation region (RA2) of the upstream nozzle blade (6A).

[0144] According to the structure of 7) above, the hub side flow road surface (44) has a region (A2) between the second wall surface (72) and the rotation area (RA2) of the upstream nozzle blade (6A) where no groove (7) is formed. Therefore, the groove (7) can be used to suppress the increase of the clearance between the hub side flow road surface (44) and the hub side end (61) of the upstream nozzle blade (6A), and the increase of the flow loss of exhaust gas caused by the increase of the clearance can be suppressed.

[0145] 8) In some embodiments, the variable capacity turbine (2) is according to any one of 1) to 7), wherein,

[0146] The hub sideflow surface (44) includes a flat surface (44A) extending radially along the turbine rotor (21).

[0147] The at least one groove (7) is configured such that its depth from the flat surface (44A) increases as it moves toward the inner periphery of the first plate portion (43).

[0148] According to the structure described in 8), by configuring the groove (7) such that its depth from the flat surface (44A) increases as it moves toward the inner circumference of the first plate (43), exhaust gas flowing along the flat surface (44A) can easily flow into the groove (7). Furthermore, the wall surface (third wall surface 73) of the groove (7) can be used to gently guide the exhaust gas flowing within the groove (7) toward the inner circumference and direct it toward the turbine rotor (21). Therefore, because turbulence in the flow of exhaust gas flowing at the hub side or within the groove (7) can be suppressed at low flow rates, the efficiency reduction of the turbine (2) at low flow rates can be suppressed.

[0149] 9) In some embodiments, according to the variable capacity turbine (2) described in 8), wherein,

[0150] The at least one groove (7) includes an inclined surface (73A) that, in a top view along the axis of the turbine rotor (21), extends in a direction intersecting the flat surface (44A) and whose inclination angle θ relative to an imaginary extension surface (44B) that extends the flat surface (44A) satisfies the condition 0° < θ < 15°.

[0151] According to the structure described in 9), if the inclination angle θ of the inclined surface (73A) relative to the imaginary extended surface (44B) is too large, exhaust gas will be stripped from the inclined surface (73A), and there is a possibility that the inclined surface (73A) cannot guide the exhaust gas. By making the inclination angle θ of the inclined surface (73A) satisfy the condition, the stripping of exhaust gas from the inclined surface (73A) can be suppressed. Therefore, the inclined surface (73A) can be used to guide the exhaust gas flowing in the groove (7) to the inner circumference.

[0152] 10) In some embodiments, the variable capacity turbine (2) is as described in any one of 1) to 9) above, wherein,

[0153] The hub sideflow surface (44) includes a flat surface (44A) extending radially along the turbine rotor (21).

[0154] The at least one groove (7) is configured such that when the wall thickness of the first plate (43) is set to T and the maximum depth of the at least one groove (7) from the flat surface (44A) is set to T1, the condition 0 < T1 ≤ 0.2T is satisfied.

[0155] According to the structure described in 10), if the maximum depth T1 of the groove (7) from the flat surface (44A) is too large, the inflow of exhaust gas into the groove (7) will increase, the mainstream flow in the exhaust gas flow path (40) will be obstructed, and there is a possibility of increased exhaust gas flow loss. By constructing the structure such that the maximum depth (T1) satisfies the condition, the groove (7) can be used to suppress the obstruction of the mainstream flow in the exhaust gas flow path (40), and the efficiency reduction of the turbine (2) can be suppressed.

[0156] 11) At least one embodiment of this disclosure relates to a turbocharger (1) comprising:

[0157] The variable capacity turbine (2) described in any of 1) to 10) above;

[0158] Centrifugal compressor (3) is configured to be driven by the variable capacity turbine (2).

[0159] According to the structure of 11), the eddy currents generated near the leading edge (213) of the hub (211) of the turbine rotor (21) at low flow rates can be reduced, thus improving the efficiency of the variable capacity turbine (2) and the turbocharger (1) equipped with the variable capacity turbine (2) at low flow rates.

[0160] Explanation of reference numerals in the attached figures

[0161] 1 turbocharger

[0162] 1A Exhaust Gas Turbocharger

[0163] 2 Variable capacity turbines

[0164] 3 Centrifugal compressor

[0165] 4. Exhaust gas flow path formation section

[0166] 5 Variable Nozzle Unit

[0167] 6 Nozzle blades

[0168] 6A upstream nozzle blade

[0169] 6B Downstream nozzle blade

[0170] 7. Groove

[0171] 10 Internal Combustion Engine

[0172] 11 Rotation axis

[0173] 12 bearings

[0174] 13. Outer shell

[0175] 14 Bearing housing

[0176] 15 Gas pipelines

[0177] 16. Exhaust gas pipeline

[0178] 17. Interior Space

[0179] 21 Turbine Rotor

[0180] 22 Turbine housing

[0181] 23 Exhaust gas inlet

[0182] 24 Exhaust gas outlet

[0183] 25 Vortex Flow Path

[0184] 26. Vortex Flow Path Formation Section

[0185] 27 Exhaust Gas Discharge Route

[0186] 28 Exhaust gas discharge path forming section

[0187] 31 Impeller

[0188] 32 Compressor housing

[0189] 33 Gas inlet

[0190] 34 Gas exhaust outlet

[0191] 35 Gas Inlet Path

[0192] 36 Gas inlet path forming section

[0193] 37 Vortex Flow Path

[0194] 38. Vortex Flow Path Formation Section

[0195] 40 Exhaust gas flow path

[0196] 41 First plate-shaped component

[0197] 42 Second plate-shaped component

[0198] 43 First Board Section

[0199] 44. Wheel hub sideflow road surface

[0200] 44A flat surface

[0201] 44B Imaginary Extended Surface

[0202] 45 Second board section

[0203] 46. ​​Protrusion

[0204] 47. Sideflow protection pavement

[0205] 48 Protective Surface

[0206] 49 Nozzle support

[0207] 51 Rotating Mechanism Section

[0208] 52 Drive ring

[0209] 53 Blade Shaft

[0210] 54-bar plate

[0211] 55 Actuator

[0212] 56 drive shafts

[0213] 57 Controller

[0214] 61 Wheel hub side end

[0215] 62 Side of the protective cover

[0216] 71 First wall

[0217] 71A Convex Surface

[0218] 72 Second wall

[0219] 73 Third wall

[0220] 73A Inclined Surface

[0221] 74 Peripheral end

[0222] 211 Wheels

[0223] 212 blades

[0224] 213 Foreshadowing

[0225] 214 Trailing edge

[0226] 431 inner periphery

[0227] 711 Downstream

[0228] 721 Upstream end

[0229] Areas A1 and A2

[0230] IL Imaginary Line

[0231] LA and LC axes

[0232] RA1, RA2 rotation areas

[0233] RC Rotation Center

[0234] RD Rotation Direction

[0235] TL tangent

[0236] V vortex

[0237] X (axis of rotation) axial direction

[0238] XC compressor side

[0239] XT Turbo Side

[0240] Y (radial axis of rotation)

Claims

1. A variable capacity turbine, characterized in that, have: Turbine rotor; A vortex flow path forming section forms a vortex flow path on the outer peripheral side of the turbine rotor; An exhaust gas flow path forming section is formed to guide exhaust gas from the vortex flow path to the turbine rotor; A variable nozzle unit, used to adjust the flow of exhaust gas in the exhaust gas flow path, includes a plurality of nozzle blades disposed in the exhaust gas flow path and configured to rotate about their respective centers of rotation. The waste gas flow path forming section includes: The first plate-shaped component has an annular first plate portion; The second plate-shaped component has an annular second plate portion disposed on the turbine outlet side in the axial direction of the turbine rotor compared to the first plate portion, defining the exhaust gas flow path between the second plate portion and the first plate portion. The first plate-shaped member has at least one groove extending from the inner periphery to the outer periphery of the first plate portion on the hub-side flow surface facing the exhaust gas path of the first plate portion. The at least one groove includes a first wall connecting an outer peripheral end of the groove to a downstream end on the inner peripheral edge of the groove, which is located downstream of the outer peripheral end in the rotational direction of the turbine rotor. The first wall surface includes a convex curved surface that, in a top view orthogonal to the axis of the turbine rotor, protrudes downstream in the direction of rotation relative to an imaginary line connecting the outer peripheral end and the downstream end on the inner peripheral edge of the groove in a straight line. The convex surface is inclined in such a way that the angle of inclination of the tangent of the convex surface relative to the radial direction of the turbine rotor in a top view orthogonal to the axis of the turbine rotor decreases as it moves toward the downstream end side.

2. The variable capacity turbine according to claim 1, wherein, The plurality of nozzle blades are included in the downstream side nozzle blades adjacent to the at least one slot on the downstream side of the turbine rotor in the direction of rotation. The hub-side flow path of the first plate-shaped component has a region in which, in a top view orthogonal to the axis of the turbine rotor, the groove is not formed between the first wall of the groove in the direction of rotation of the turbine rotor and the rotation area of ​​the downstream nozzle blade.

3. The variable capacity turbine according to claim 1, wherein, The at least one groove further includes a second wall connecting the outer peripheral end of the groove to an upstream end on the inner peripheral edge of the groove located upstream of the turbine rotor in the direction of rotation relative to the outer peripheral end.

4. The variable capacity turbine according to claim 3, wherein, The plurality of nozzle blades are included in the upstream nozzle blades adjacent to the at least one slot on the upstream side of the turbine rotor in the direction of rotation. The hub-side flow path of the first plate-shaped component has a region in which, in a top view orthogonal to the axis of the turbine rotor, the groove is not formed between the second wall of the groove in the direction of rotation of the turbine rotor and the rotation area of ​​the upstream nozzle blade.

5. The variable capacity turbine according to claim 1, wherein, The hub sideflow surface comprises a flat surface extending radially along the turbine rotor. The at least one groove is configured such that its depth from the flat surface increases as it faces the inner peripheral side of the first plate portion.

6. The variable capacity turbine according to claim 5, wherein, The at least one slot includes an inclined surface that, in a top view along the axis of the turbine rotor, extends in a direction intersecting the flat surface, and the inclination angle θ relative to an imaginary extension surface that extends the flat surface satisfies the condition 0° < θ < 15°.

7. The variable capacity turbine according to any one of claims 1 to 6, wherein, The hub sideflow surface comprises a flat surface extending radially along the turbine rotor. The at least one groove is configured such that when the wall thickness of the first plate is set to T and the maximum depth of the at least one groove from the flat surface is set to T1, the condition 0 < T1 ≤ 0.2T is satisfied.

8. A turbocharger comprising: The variable capacity turbine according to any one of claims 1 to 7; A centrifugal compressor configured to be driven by the variable capacity turbine.

Images