JP7688780B2 - Variable nozzle unit, turbine and turbocharger - Google Patents

Description

The present disclosure relates to a variable nozzle unit, and a turbine and turbocharger equipped with the variable nozzle unit.

Turbochargers that use the energy of exhaust gas from an internal combustion engine to supercharge the intake air of the engine are known to have variable-capacity turbines (see, for example, Patent Document 1). In a variable-capacity turbine, multiple nozzle vanes are arranged in the circumferential direction of the turbine wheel in an exhaust gas flow passage that sends exhaust gas from the scroll flow passage of the turbine to the turbine wheel, and the blade angle of these nozzle vanes can be changed from the outside by an actuator to adjust the flow passage cross-sectional area of the exhaust gas flow passage (the flow passage between adjacent nozzle vanes). A variable-capacity turbine adjusts the flow passage cross-sectional area of the exhaust gas flow passage to change the flow speed and pressure of the exhaust gas led to the turbine wheel, thereby enhancing the supercharging effect.

To improve the performance of a variable geometry turbine, it is effective to suppress leakage flow from the gap at the end face of the nozzle vane. For this reason, in the past, the distance between the two plate-like members (nozzle mount, nozzle plate) that form the exhaust gas flow passage was adjusted using the nozzle support to keep the gap at the end face of the vane to a minimum. Also, to make it easier to assemble the variable nozzle mechanism into the housing, a method of integrating the variable nozzle mechanism is sometimes used, whereby both ends of the nozzle support are fixed to the nozzle mount and nozzle plate by crimping or welding.

JP 2013-072401 A

By integrating the variable nozzle mechanism, the process of assembling the variable nozzle mechanism into the housing can be simplified. However, with the current structure, assembling the variable nozzle mechanism requires crimping and welding processes, and special assembly equipment is required to perform these processes. For this reason, it is desirable to improve the assembly ease of the variable nozzle mechanism.

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

In view of the above circumstances, at least one embodiment of the present disclosure aims to provide a variable nozzle unit, turbine, and turbocharger that can improve the assembly of the variable nozzle unit and suppress damage during thermal deformation.

The variable nozzle unit according to at least one embodiment of the present disclosure includes:
A variable nozzle unit that is mounted on a turbine and is configured to be able to vary a flow passage area of gas supplied to a turbine wheel,
A first plate-shaped member including an annular first plate portion;
a second plate member including an annular second plate portion that forms a gas flow path between itself and the first plate portion, the second plate portion being disposed opposite to the first plate portion on one side of the first plate portion in the axial direction of the variable nozzle unit;
at least one variable nozzle vane provided in the gas flow passage and rotatably supported by the first plate-shaped member or the second plate-shaped member;
at least one fastening member fastening the first plate member and the second plate member to form a first gap between the first plate portion and the second plate portion;
The at least one fastening member is
a first clamping portion having a recess that opens toward an inner side in a radial direction of the variable nozzle unit and clamps an outer circumferential edge portion of the first plate portion;
a second clamping portion having a recess that opens toward the inside in the radial direction and clamps an outer peripheral edge portion of the second plate portion;
The plate-shaped connecting portion has one end connected to the first clamping portion and the other end connected to the second clamping portion.

A turbine according to at least one embodiment of the present disclosure includes:
The variable nozzle unit is provided.

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.

At least one embodiment of the present disclosure provides a variable nozzle unit, turbine, and turbocharger that can improve the assembly of the variable nozzle unit and suppress damage during thermal deformation.

1 is a schematic diagram of an internal combustion engine system including a turbocharger according to an embodiment; 1 is a schematic cross-sectional view along the axis of a turbine according to an embodiment; FIG. 2 is a schematic diagram of a variable nozzle unit included in a turbine according to an embodiment. 1 is a schematic cross-sectional view showing a cross section along an axis line on one side of an axis line of a turbine according to an embodiment of the present invention. 1 is a schematic cross-sectional view showing a cross section along an axis on one side of the axis of a variable nozzle unit according to one embodiment. FIG. 1 is a schematic cross-sectional view showing a cross section perpendicular to the axis of a variable nozzle unit according to one embodiment. 1 is a schematic cross-sectional view showing a cross section along an axis on one side of the axis of a variable nozzle unit according to one embodiment. FIG. 1 is a schematic cross-sectional view showing a cross section along an axis on one side of the axis of a variable nozzle unit according to one embodiment. FIG. 1 is a schematic cross-sectional view showing a cross section along an axis on one side of the axis of a variable nozzle unit according to one embodiment. FIG. 10 is a schematic cross-sectional view showing an example of a cross section taken along line AB of FIG. 9 of a connection portion of a fastening member according to one embodiment. FIG. 11 is a schematic view showing the fastening member shown in FIG. 10 as viewed from the outside in the radial direction. FIG. 10 is a schematic cross-sectional view showing an example of a cross section taken along line AB of FIG. 9 of a connection portion of a fastening member according to one embodiment. FIG. 1 is a schematic cross-sectional view showing a cross section along an axis on one side of the axis of a variable nozzle unit according to one embodiment. FIG. FIG. 14 is a perspective view of the fastener shown in FIG. 13 . 14 is a schematic cross-sectional view showing a cross section perpendicular to the axis of the variable nozzle unit shown in FIG. 13.

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

(Turbocharger)
FIG. 1 is a schematic diagram of an internal combustion engine system 10 including a turbocharger 1 according to an embodiment. The turbine 2 according to the present disclosure can be mounted on, for example, a turbocharger (supercharger) 1 for automobiles, ships, or industries (for example, for land-based power generation). In the following embodiments, the turbine 2 mounted on the turbocharger 1 will be described as an example, but the turbine 2 according to the present disclosure is not limited to being mounted on the turbocharger 1. In addition, 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 single turbine 2 or may be configured in combination with a mechanism or device other than the centrifugal compressor 12 as long as it is capable of converting the working fluid energy into mechanical power (for example, rotational force). In addition, there is no need to limit the use of the turbine 2.

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

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

1, the turbocharger 1 further includes a rotating shaft 15 to which the turbine wheel 3 is connected at one end and the impeller 13 is connected at the other end, 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.

The turbine 2 of the turbocharger 1 is configured to rotate the turbine wheel 3 using the energy of exhaust gas discharged from the internal combustion engine 11. The impeller 13 is coaxially connected to the turbine wheel 3 via a rotating 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 draw air (supply air, gas) into the compressor housing 14, compress the air, and send the compressed air to the internal combustion engine 11 by driving the impeller 13 to rotate about an axis LA.

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. The exhaust gas generated by the combustion in the internal combustion engine 11 is sent from the internal combustion engine 11 to the turbine 2, which rotates the turbine wheel 3.

(Impeller)
1, the impeller 13 is connected to the other end side of the rotating shaft 15 and is provided so as to be rotatable integrally with the rotating shaft 15 about the axis of the impeller 13. The impeller 13 is configured to guide air introduced along the axial direction of the impeller 13 to the outside in the radial direction of the impeller 13. In the illustrated embodiment, the impeller 13 is an open-type impeller that does not include an annular member surrounding the outer periphery of the blades of the impeller 13.

(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.

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.

The scroll passage 142 is provided on the outer periphery of the impeller 13 and consists of 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.

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

(Turbine wheel)
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 circumferential surface of the hub 31. The plurality of turbine blades 32 are arranged at intervals from one another in the circumferential direction about the axis line LA. The hub 31 and the plurality of turbine blades 32 are provided so as to be rotatable integrally with the rotating shaft 15 about the axis line 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 front side of the turbine wheel 3 along the axial direction of the turbine wheel 3.

(Scroll passage, exhaust gas discharge passage)
Inside the first housing 4, 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. In other words, the first housing 4 has the scroll passage 41 and the exhaust gas discharge passage 42. The scroll passage 41 is provided on the outer periphery of the turbine wheel 3 and is a spiral passage extending along the circumferential direction of the turbine wheel 3. The exhaust gas discharge passage 42 extends from the turbine wheel 3 toward the front side along the axial direction of the turbine wheel 3.

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

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 drives 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.

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

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

(First plate-like member)
The first plate member (nozzle mount) 7 includes an annular first plate portion 71 extending 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 facing the gas flow path 43A is formed on the front side of the first plate portion 71, and a first back surface 73 is formed on the rear side of the first plate portion 71, i.e., on the opposite side to the first flow path surface 72.

(Second plate-like member)
The second plate-like member (nozzle plate) 8 is disposed opposite the first plate portion 71 and includes an annular second plate portion 81 that forms a gas flow passage 43A from the scroll flow passage 41 toward the turbine wheel 3 between the first plate portion and the second plate portion. The second plate portion 81 is disposed forward of the first plate portion 71 and extends along the circumferential direction of the turbine wheel 3 on the outer circumferential side of the turbine wheel 3. A second flow passage surface 82 facing the gas flow passage 43A is formed on the rear side of the second plate portion 81, and a second back surface 83 is formed on the front side of the second plate portion 81, i.e., on the opposite side to the second flow passage surface 82.

The gas flow passage 43A is formed between the first flow passage surface 72 and the second flow passage surface 82. The first flow passage surface 72 is located rearward of the second flow passage surface 82 and faces the second flow passage surface 82. The exhaust gas introduced into the inside of the turbine 2 passes through the scroll flow passage 41 and then the gas flow passage 43A, and is then guided to the turbine wheel 3 to rotate the turbine wheel 3.

(first space)
The second housing 5 has an opposing surface 51 that faces the first back surface 73 of the first plate portion 71 with the first space 43B interposed therebetween. The first space 43B is a part of the internal space 43, and is formed on the opposite side of the first plate portion 71 to the gas flow path 43A.

(Variable nozzle vane)
Each of the variable nozzle vanes 61 is disposed in the gas flow passage 43A and supported by the first plate portion 71 (first plate-shaped member 7) or the second plate portion 81 (second plate-shaped member 8) so as to be rotatable about its own rotation center RC. The variable nozzle vanes 61 are disposed at intervals in the circumferential direction of the turbine wheel 3.

(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.

(Drive mechanism, control device)
2, the turbine 2 further includes a drive mechanism unit (actuator) 65 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) 66 configured to control the rotation of the annular member 62 about the axis LB. The drive mechanism unit 65 includes an electric motor that generates a drive force, an air cylinder that transmits the drive force, and the like.

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

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 portion 621A formed in the outer peripheral edge portion of the annular member 62, and the fitting portion 631A is accommodated inside the groove portion 621A and is loosely fitted into the groove portion 621A. The first plate portion 71 has a plurality of through holes 74 that penetrate the first flow path surface 72 and the first back surface 73. The plurality of through holes 74 are respectively 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 variable nozzle vanes 61 and the link members 63. The other end of each link member 63 is inserted through the through hole 74 that corresponds to the link member 63 individually and is connected to the variable nozzle vane 61 that corresponds to the link member 63 individually.

When the annular member 62 is rotated to one side in the circumferential direction of the turbine wheel 3, the variable nozzle vanes 61 adjacent to each other in the circumferential direction move (rotate) away from each other, and the flow passage cross-sectional area of the gas flow passage 43A between the variable nozzle vanes 61 increases. When the annular member 62 is rotated to the other side in the circumferential direction of the turbine wheel 3, the variable nozzle vanes 61 adjacent to each other in the circumferential direction move (rotate) toward each other, and the flow passage cross-sectional area of the gas flow passage 43A between the variable nozzle vanes 61 decreases.

The variable nozzle unit 6 transmits a driving force from the outside of the variable nozzle unit 6 (drive mechanism 65) to the multiple variable nozzle vanes 61 via the annular member 62 and multiple link members 63, causing the multiple variable nozzle vanes 61 to rotate around their respective rotation centers RC, thereby changing the blade angle of each, 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 variable nozzle unit 6, thereby controlling the supercharging pressure of the turbine 2.

(Using member)
4 is a schematic cross-sectional view showing a cross section along an axis on one side of the axis LA of the turbine 2 according to one embodiment. As shown in FIG. 4, the turbine 2 further includes a biasing member 21 that is disposed between the second housing 5 and the first plate-shaped member 7 and configured to bias the first plate portion 71 toward the gas flow path 43A.

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

The first housing 4 includes an engaging portion 44 that extends radially along the turbine wheel 3 and engages with the outer peripheral edge portion 76 of the first plate portion 71. The engaging portion 44 has a rear scroll flow passage surface 441 that extends radially outward from the rear end P1 of the scroll flow passage 41, and an engaging surface 442 that is located on the opposite side in the axial direction from the rear scroll flow passage surface 441 and faces the first space 43B.

The first plate member 7 is biased forward by the biasing member 21, so that the outer peripheral edge 76 of the first plate portion 71 is pressed against the engaging portion 44 of the first housing 4, and the engaging surface 76A on the front side of the outer peripheral edge 76 abuts against the engaging surface 442. This seals the space between the engaging surface 76A on the front side and the engaging surface 442, thereby suppressing the inflow of exhaust gas from the scroll flow path 41 to the first space 43B. In the illustrated embodiment, the engaging surface 76A is a stepped surface formed radially outward and rearward of the first flow path surface 72. In some other embodiments, the outer peripheral edge 76 of the first plate portion 71 may be sandwiched between the first housing 4 and the second housing 5.

4, the first housing 4 includes a forward facing surface 45 that faces the second back surface 83 of the second plate portion 81, and a shroud portion 46 that protrudes rearward from the forward facing surface 45, radially inward from the second plate portion 81 and the forward facing surface 45. The shroud portion 46 has a shroud surface 46A that is convexly curved to face the tip ends (tips) of the multiple turbine blades 32, and a gap (clearance) is formed between the shroud surface 46A and the tip ends.

(Fastening member)
Each of Figures 5, 7 to 9, and 13 is a schematic cross-sectional view showing a cross-section along the axis LC on one side of the axis LC of the variable nozzle unit 6 according to one embodiment. In some embodiments, the above-mentioned variable nozzle unit 6 further includes at least one fastening member 9 that fastens the first plate member 7 and the second plate member 8 to form a first gap G between the first plate portion 71 and the second plate portion 81, as shown in Figure 5. As shown in Figures 5, 7 to 9, and 13, the at least one fastening member 9 includes a first clamping portion 91, a second clamping portion 92, and a connecting portion 93.
It should be noted that the variable nozzle unit 6 does not have a conventional nozzle support which is fixed to the first plate portion 71 and the second plate portion 81 and supports the first plate member 7 and the second plate member 8 in a spaced-apart state from each other.

The first clamping portion 91 has a recess 91A that opens toward the inside in the radial direction of the variable nozzle unit 6, and is configured to clamp the outer peripheral edge portion 76 (77) of the first plate portion 71. The second clamping portion 92 has a recess 92A that opens toward the inside in the radial direction of the variable nozzle unit 6, and is configured to clamp the outer peripheral edge portion 84 of the second plate portion 81. The connection portion 93 is formed in a plate shape, one end of which is connected to the first clamping portion 91, and the other end of which is connected to the second clamping portion 92. When mounted on the variable nozzle unit 6, the connection portion 93 is provided in the gas flow path 43A, and is configured to be located outside the variable nozzle vane 61 in the radial direction of the variable nozzle unit 6.

The fastening member 9 can clamp the outer peripheral edge portion 76 (77) of the first plate portion 71 in the first clamping portion 91 by fitting the outer peripheral edge portion 76 (77) of the first plate portion 71 into the recess 91A formed in the first clamping portion 91. The fastening member 9 can clamp the outer peripheral edge portion 84 of the second plate portion 81 in the second clamping portion 92 by fitting the outer peripheral edge portion 84 of the second plate portion 81 into the recess 92A formed in the second clamping portion 92. This allows the first plate member 7 and the second plate member 8 to be fastened so as to form a first gap G between the first plate member 7 and the second plate member 8. In this case, since no labor-intensive process such as crimping or welding is required when fastening the first plate member 7 and the second plate member 8, the assembly of the variable nozzle unit 6 can be improved compared to the case where a conventional nozzle support is used to fasten the first plate member 7 and the second plate member 8.

When high-temperature exhaust gas flows into the gas flow passage 43A of the turbine 2 during operation, the variable nozzle unit 6 may be thermally deformed, and stress may occur in the connection portion 93 due to the difference in thermal expansion between the first plate-shaped member 7 and the second plate-shaped member 8. According to the above configuration, the connection portion 93 of the fastening member 9 is plate-shaped, so its rigidity can be reduced compared to conventional nozzle supports. By reducing the rigidity of the connection portion 93, it is possible to reduce the stress generated in the connection portion 93 due to the difference in thermal expansion between the first plate-shaped member 7 and the second plate-shaped member 8 when the variable nozzle unit 6 is thermally deformed, and damage to the connection portion 93 when the variable nozzle unit 6 is thermally deformed can be suppressed.

(First clamping part, second clamping part)
5, 7 to 9, and 13, the first clamping portion 91 includes a pair of first clamping pieces 94, 95, and a first connecting piece 96 that connects the outer circumferential ends (radially outer ends) of the pair of first clamping pieces 94, 95. The second clamping portion 92 includes a pair of second clamping pieces 97, 98, and a second connecting piece 99 that connects the outer circumferential ends (radially outer ends) of the pair of second clamping pieces 97, 98.

The recess 91A is formed by the mutually facing inner surfaces of the pair of first clamping pieces 94, 95 and the inner surface of the first connecting piece 96 (the radially inner surface continuing to each of the inner surfaces of the pair of first clamping pieces 94, 95). The pair of first clamping pieces 94, 95 are configured to clamp the first flow path surface 72 and the first back surface 73 of the first plate portion 71. The pair of first clamping pieces 94, 95 includes a first outer clamping piece 94 facing the first back surface 73 and a first inner clamping piece 95 facing the first flow path surface 72. The first outer clamping piece 94, the first inner clamping piece 95, and the first connecting piece 96 are formed in a plate shape.

The first connecting piece 96 extends along the axial direction of the variable nozzle unit 6. The first outer clamping piece 94 extends from the rear end (the other end) of the first clamping piece 94 toward the inside in the radial direction along the radial direction of the variable nozzle unit 6, and at least a portion of it abuts against the first back surface 73. The first inner clamping piece 95 extends from the front end (one end) of the first clamping piece 94 toward the inside in the radial direction along the radial direction of the variable nozzle unit 6, and at least a portion of it abuts against the first flow path surface 72.

The recess 92A is formed by the mutually facing inner surfaces of the pair of second clamping pieces 97, 98 and the inner surface of the second connecting piece 99 (the radially inner surface continuing to each of the inner surfaces of the pair of second clamping pieces 97, 98). The pair of second clamping pieces 97, 98 are configured to clamp the second flow path surface 82 and the second back surface 83 of the second plate portion 81. The pair of second clamping pieces 97, 98 includes a second outer clamping piece 97 facing the second back surface 83 and a second inner clamping piece 98 facing the second flow path surface 82. The second outer clamping piece 97, the second inner clamping piece 98, and the second connecting piece 99 are formed in a plate shape.

The second connecting piece 99 extends along the axial direction of the variable nozzle unit 6. The second outer clamping piece 97 extends from the front end (one end) of the second connecting piece 99 toward the inside in the radial direction along the radial direction of the variable nozzle unit 6, and at least a portion of it abuts against the second back surface 83. The second inner clamping piece 98 extends from the rear end (the other end) of the second connecting piece 99 toward the inside in the radial direction along the radial direction of the variable nozzle unit 6, and at least a portion of it abuts against the second flow path surface 82.

According to the above configuration, the first connecting piece 96 applies an elastic force to the pair of first clamping pieces 94, 95 in the clamping direction, so that the first clamping portion 91 can firmly clamp the first plate portion 71. The second connecting piece 99 applies an elastic force to the pair of second clamping pieces 97, 98 in the clamping direction, so that the second clamping portion 92 can firmly clamp the second plate portion 81. Therefore, the fastening member 9 can firmly fasten the first plate member 7 and the second plate member 8. The first clamping portion 91 can move in the radial direction in accordance with the thermal expansion of the first plate member 7 when the first plate member 7 is thermally deformed in the radial direction, and the second clamping portion 92 can move in the radial direction in accordance with the thermal expansion of the second plate member 8 when the second plate member 8 is thermally deformed in the radial direction. This can reduce the above-mentioned stress generated in the connecting portion 93 when the variable nozzle unit 6 is thermally deformed.

6 is a schematic cross-sectional view showing a cross section perpendicular to the axis LC of the variable nozzle unit 6 according to one embodiment. In some embodiments, as shown in FIG. 6, the at least one fastening member 9 described above includes a plurality of fastening members 9 arranged at intervals in the circumferential direction of the variable nozzle unit 6. In the embodiment shown in FIG. 6, the outer peripheral edge portion 76 of the first plate portion 71 has a plurality of recessed grooves 77 recessed toward the inside in the radial direction of the variable nozzle unit 6, and the plurality of recessed grooves 77 are formed at intervals in the circumferential direction of the variable nozzle unit 6. The first clamping portion 91 of each of the plurality of fastening members 9 may be attached to the recessed groove 77 so that the first connecting piece 96 faces the bottom surface 77A of the recessed groove 77. By attaching a plurality of fastening members 9 in the circumferential direction of the variable nozzle unit 6, it is possible to suppress relative positional deviation between the first plate-shaped member 7 and the second plate-shaped member 8. In addition, the first clamping portion 91 of each of the multiple fastening members 9 may be attached to a portion of the outer peripheral edge portion 76 of the first plate portion 71 other than the groove 77, or may be attached to the outer peripheral edge portion 76 of the first plate portion 71 that does not have the groove 77.

In some embodiments, as shown in Figures 5, 7 to 9 and 13, the above-mentioned connection portion 93 has one end (rear end) connected to the radially inner end of the first inner clamping piece 95 and the other end (front end) connected to the radially inner end of the second inner clamping piece 98.

According to the above configuration, the structure of the fastening member 9 is simplified, and the fastening member 9 having the first clamping portion 91, the second clamping portion 92, and the connecting portion 93 can be formed by bending a single plate-shaped member (e.g., a metal plate). In this case, the fastening member 9 is relatively lightweight and easy to manufacture, so that the material cost and manufacturing cost of the fastening member 9 can be reduced. In addition, the fastening member 9 can be easily attached to the first plate portion 71 and the second clamping portion 92 to the second plate portion 81 by bending the connection portion with the connection portion 93 of the first clamping portion 91 or the second clamping portion 92, or the connection portion 93 itself. This improves the ease of assembly of the variable nozzle unit 6.

(first slope)
7 to 9, the first outer clamping piece 94 is inclined toward the front side (one axial side, toward the gas flow path 43A) as it moves radially inward from the first connecting piece 96. The first back surface 73 of the first plate portion 71 is inclined toward the front side (one axial side) as it moves radially inward, and includes a first inclined surface 731 on which the first outer clamping piece 94 is engaged. In the embodiment shown in FIG. 7, an outer peripheral end 732 of the first inclined surface 731 is continuous with a bottom surface 77A of the recessed groove 77.

According to the above configuration, by engaging the first outer clamping piece 94 with the first inclined surface 731 of the first plate portion 71, the first outer clamping piece 94 becomes difficult to remove from the first plate portion 71, thereby preventing the first outer clamping piece 94 from falling off from the first plate portion 71.

(First opposing surface)
8 and 9 , the first back surface 73 of the first plate portion 71 includes the first inclined surface 731 and a first opposing surface 733 that faces the first outer clamping piece 94 via a gap G1 radially outward from the first inclined surface 731. In the illustrated embodiment, an outer circumferential end 732 of the first inclined surface 731 is continuous with the first opposing surface 733, and an outer circumferential end 734 of the first opposing surface 733 is continuous with the bottom surface 77A of the recessed groove 77.

According to the above configuration, by providing the first opposing surface 733 that faces the first outer clamping piece 94 across the gap G1, it is easier to engage the first outer clamping piece 94 with the first inclined surface 731 than when the first opposing surface 733 is not provided, and this makes it easier to attach the first clamping portion 91 to the first plate portion 71. This further improves the ease of assembly of the variable nozzle unit 6.

In some embodiments, as shown in FIG. 9, the first opposing surface 733 described above is inclined toward the forward side (one side in the axial direction, toward the gas flow path 43A) as it moves radially outward from the outer circumferential end 732 of the first inclined surface 731.

According to the above configuration, when the first clamping portion 91 is attached to the first plate portion 71, the tip (the inner end in the radial direction) of the first outer clamping piece 94 contacts the first opposing surface 733 and opens toward the first connecting piece 96, so that the first clamping portion 91 can be easily attached to the first plate portion 71. This can further improve the assembly of the variable nozzle unit 6. Note that the first opposing surface 733 only needs to have a gap G1 formed between it and the first outer clamping piece 94. That is, in some other embodiments, the first opposing surface 733 may extend radially outward from the outer circumferential end 732 of the first inclined surface 731 along the radial direction, or may be inclined toward the rear side (the other side in the axial direction) as it moves radially outward from the outer circumferential end 732.

(Second slope)
7 to 9, the second outer clamping piece 97 is inclined toward the rear side (the other axial side, toward the gas flow path 43A) as it moves radially inward from the second connecting piece 99. The second back surface 83 of the second plate portion 81 is inclined toward the rear side (the other axial side) as it moves radially inward, and includes a second inclined surface 831 on which the second outer clamping piece 97 is engaged. In the embodiment shown in FIG. 7, an outer peripheral end 832 of the second inclined surface 831 is continuous with the outer peripheral surface of the outer circumferential edge portion 84.

According to the above configuration, by engaging the second outer clamping piece 97 with the second inclined surface 831 of the second plate portion 81, the second outer clamping piece 97 becomes difficult to remove from the second plate portion 81, thereby preventing the second outer clamping piece 97 from falling off from the second plate portion 81.

(Second opposing surface)
8 and 9 , the second back surface 83 of the second plate portion 81 includes the second inclined surface 831 and a second opposing surface 833 that faces the second outer clamping piece 97 via a gap G2 radially outward from the second inclined surface 831. In the illustrated embodiment, an outer circumferential end 832 of the second inclined surface 831 is continuous with the second opposing surface 833, and an outer circumferential end 834 of the second opposing surface 833 is continuous with the outer circumferential surface of the outer circumferential edge portion 84.

According to the above configuration, by providing the second outer clamping piece 97 with the second opposing surface 833 that faces the second outer clamping piece 97 via the gap G2, it is easier to engage the second outer clamping piece 97 with the second inclined surface 831 than when the second opposing surface 833 is not provided, and this makes it easier to attach the second clamping part 92 to the second plate part 81. This further improves the ease of assembly of the variable nozzle unit 6.

In some embodiments, as shown in FIG. 9, the second opposing surface 833 is inclined toward the rear side (the other axial side, toward the gas flow path 43A) as it moves radially outward from the outer circumferential end 832 of the second inclined surface 831.

According to the above configuration, when the second clamping portion 92 is attached to the second plate portion 81, the tip (the inner end in the radial direction) of the second outer clamping piece 97 contacts the second opposing surface 833 and opens toward the second connecting piece 99, so that the second clamping portion 92 can be easily attached to the second plate portion 81. This further improves the ease of assembly of the variable nozzle unit 6. It is sufficient that a gap G2 is formed between the second opposing surface 833 and the second outer clamping piece 97. That is, in some other embodiments, the second opposing surface 833 may extend radially from the outer peripheral end 832 of the second inclined surface 831 toward the outside in the radial direction, or may be inclined toward the front side (one side in the axial direction) as it moves radially outward from the outer peripheral end 832.

The variable nozzle unit 6 may be configured to have either a first opposing surface 733 that faces the first outer clamping piece 94 via a gap G1, or a second opposing surface 833 that faces the second outer clamping piece 97 via a gap G2, or may be configured to have both the first opposing surface 733 and the second opposing surface 833. When the variable nozzle unit 6 has both the first opposing surface 733 and the second opposing surface 833, the fastening member 9 can be attached to the first plate portion 71 or the second plate portion 81 more easily than when the variable nozzle unit 6 has either the first opposing surface 733 or the second opposing surface 833, thereby improving the assembly of the variable nozzle unit 6.

(Return of the first outer clamping piece)
9, a barb 941 that inclines rearward (to the other axial direction) as it moves radially inward is provided on the radially inner end of the first outer clamping piece 94. The barb 941 is plate-shaped and can be formed by subjecting the first outer clamping piece 94 to bending processing or the like.

According to the above configuration, by providing the barb 941 at the tip (the inner end in the radial direction) of the first outer clamping piece 94, the frictional resistance between the first outer clamping piece 94 and the first plate portion 71 can be reduced, making it easier to attach the first clamping piece 91 to the first plate portion 71. This further improves the ease of assembly of the variable nozzle unit 6.

(Return of the second outer clamping piece)
9, a barb 971 that inclines forward (to one axial side) as it moves radially inward is provided on the radially inner end of the second outer clamping piece 97. The barb 971 is plate-shaped and can be formed by subjecting the second outer clamping piece 97 to bending processing or the like.

According to the above configuration, by providing a barb 971 at the tip (the inner end in the radial direction) of the second outer clamping piece 97, the frictional resistance between the second outer clamping piece 97 and the second plate portion 81 can be reduced, making it easier to attach the second clamping portion 92 to the second plate portion 81. This further improves the ease of assembly of the variable nozzle unit 6.

The above-mentioned variable nozzle unit 6 may be configured to have either the barb 941 of the first outer clamping piece 94 or the barb 971 of the second outer clamping piece 97, and when the variable nozzle unit 6 has both the barb 941 and the barb 971, it is easier to attach the fastening member 9 to the first plate portion 71 or the second plate portion 81 than when it has only one of the barb 941 or the barb 971, thereby improving the assembly ability of the variable nozzle unit 6.

(Bent part of connection)
FIG. 10 is a schematic cross-sectional view showing an example of the A-B cross section shown in FIG. 9 of the connection portion 93 of the fastening member 9 in one embodiment. FIG. 11 is a schematic view showing the fastening member 9 shown in FIG. 10 as viewed from the outside in the radial direction. In some embodiments, the above-mentioned connection portion 93 (93A) has a bent portion 931 that is convex toward the outside (illustrated example) or the inside in the radial direction and extends along the axial direction in at least a part of the cross section (see FIG. 10) perpendicular to the axial direction of the variable nozzle unit 6 (see FIG. 11). In the embodiment shown in FIG. 11, the bent portion 931 is formed from one end (rear end) to the other end (front end) of the connection portion 93, but may be formed continuously or intermittently in a part of the connection portion 93 in the axial direction.

According to the above configuration, by providing the connection portion 93 with the bent portion 931 extending along the axial direction, it is possible to suppress the occurrence of buckling of the connection portion 93 when a load acts on the connection portion 93 along the axial direction of the variable nozzle unit 6. By suppressing the occurrence of buckling of the connection portion 93, it is possible to maintain the first gap G at a predetermined distance, and therefore it is possible to suppress malfunction of the variable nozzle vane 61 due to a reduction in the first gap G.

(Bending shape of connection part)
Fig. 12 is a schematic cross-sectional view showing an example of the A-B cross section of the connection portion 93 of the fastening member 9 in one embodiment shown in Fig. 9. In some embodiments, the above-mentioned connection portion 93 (93B) is curved toward either the outside (illustrated example) or the inside in the radial direction in a cross section perpendicular to the axial direction of the variable nozzle unit 6 (see Fig. 12).

According to the above configuration, by curving the connection portion 93 toward either the outside or the inside in the radial direction in a cross section perpendicular to the axial direction, it is possible to suppress the occurrence of buckling of the connection portion 93 when a load acts on the connection portion 93 along the axial direction of the variable nozzle unit 6. By suppressing the occurrence of buckling of the connection portion 93, the first gap G can be maintained at a predetermined distance, and therefore malfunction of the variable nozzle vane 61 due to a reduction in the first gap G can be suppressed.

(Gas flow straightening through connection parts)
Fig. 14 is a perspective view of the fastening member 9 shown in Fig. 13. Fig. 15 is a schematic cross-sectional view showing a cross section perpendicular to the axis LC of the variable nozzle unit 6 shown in Fig. 13. In some embodiments, as shown in Fig. 15, when the side where the leading edge 611 is located relative to the trailing edge 612 of the variable nozzle vane 61 in the circumferential direction of the variable nozzle unit 6 is the upstream side, and the side where the trailing edge 612 is located relative to the leading edge 611 is the downstream side, the above-mentioned connection portion 93 is inclined so that the downstream end 932 is located radially inward relative to the upstream end 933 in a cross section perpendicular to the axial direction. Note that the inclination direction of the connection portion 93 is preferably a direction along the inflow angle of the variable nozzle vane 61.

14, in the illustrated embodiment, the above-mentioned connection portion 93 has one end (rear end) of the upstream end 933 connected to the radially inner end of the first inner clamping piece 95, and the other end (front end) of the upstream end 933 connected to the radially inner end of the second inner clamping piece 98. The downstream end 932 is located radially inner than the first inner clamping piece 95 and the second inner clamping piece 98, and is not connected to the first inner clamping piece 95 and the second inner clamping piece 98. The connection portion 93 can be formed by cutting, bending, or the like.

According to the above configuration, the connection portion 93 is inclined so that its downstream end 932 is positioned radially inward relative to its upstream end 933, thereby straightening the flow of gas toward the variable nozzle vane 61 and smoothing the flow of gas into the variable nozzle vane 61, thereby improving the performance of the turbine 2 equipped with the variable nozzle unit 6.

In some embodiments, as shown in FIG. 15, the at least one variable nozzle vane 61 includes a plurality of variable nozzle vanes 61 arranged at different circumferential positions at intervals in the circumferential direction of the variable nozzle unit 6. In the case where the side where the leading edge 611 is located relative to the trailing edge 612 of the variable nozzle vane 61 in the circumferential direction of the variable nozzle unit 6 is the upstream side, and the side where the trailing edge 612 is located relative to the leading edge 611 is the downstream side, each of the above-mentioned plurality of fastening members 9 is configured such that a straight line SL extending from the downstream end 932 of the connection portion 93 passes upstream of a middle position CP of the rotation axis RC of two variable nozzle vanes 61 adjacent to the fastening member 9 in the circumferential direction in a virtual circle VC passing through the rotation axis RC of each of the plurality of variable nozzle vanes 61. The straight line SL extends along the inclination direction of the connection portion 93, and the gas guided by the connection portion 93 flows along the extension direction of the straight line SL (the inclination direction of the connection portion 93).

According to the above configuration, the gas flow toward the variable nozzle vanes 61, which has been straightened by the connection portion 93, passes upstream of the midpoint CP between two adjacent variable nozzle vanes 61 in the circumferential direction relative to the fastening member 9. In this case, the gas can flow smoothly into the multiple variable nozzle vanes 61, thereby improving the performance of the turbine 2 equipped with the variable nozzle unit 6.

As shown in Figure 2, the turbine 2 according to some embodiments includes a variable nozzle unit 6 having the above-mentioned fastening member 9. As shown in Figure 1, the turbocharger 1 according to some embodiments includes the above-mentioned turbine 2 and the above-mentioned centrifugal compressor 12 configured to be driven by the turbine 2. In these cases, damage to the variable nozzle unit 6 during thermal deformation can be suppressed, thereby improving the reliability of the turbine 2 including the variable nozzle unit 6.

In this specification, expressions expressing relative or absolute configuration, such as "in a certain direction,""along a certain direction,""parallel,""orthogonal,""center,""concentric," or "coaxial," do not only strictly represent such a configuration, but also represent 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 indicating that things are in an equal state, such as "identical,""equal," and "homogeneous," not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained.
Furthermore, in this specification, expressions describing shapes such as a rectangular shape or a cylindrical shape do not only refer to shapes such as a rectangular shape or a cylindrical shape in the strict geometric sense, but also refer to shapes that include uneven portions, chamfered portions, etc., to the extent that the same effect can be obtained.
In addition, in this specification, the expressions "comprise,""include," or "have" a certain element are not exclusive expressions that exclude the presence of other elements.

The present disclosure is not limited to the above-described embodiments, but also includes variations on the above-described embodiments and suitable combinations of these embodiments.

The contents described in the above-mentioned embodiments can be understood, for example, as follows:

1) The variable nozzle unit (6) according to at least one embodiment of the present disclosure comprises:
A variable nozzle unit (6) configured to be mounted on a turbine (2) so as to be capable of varying a flow passage area of gas supplied to a turbine wheel (3),
A first plate-shaped member (7) including an annular first plate portion (71);
a second plate-shaped member (8) including an annular second plate portion (81) that forms a gas flow path (43A) between itself and the first plate portion (71), the second plate portion (81) being disposed opposite the first plate portion (71) on one side of the first plate portion (71) in the axial direction of the variable nozzle unit (6);
at least one variable nozzle vane (61) provided in the gas flow passage (43A) and rotatably supported by the first plate-shaped member (7) or the second plate-shaped member (8);
and at least one fastening member (9) that fastens the first plate member (7) and the second plate member (8) to form a first gap (G) between the first plate portion (71) and the second plate portion (81),
The at least one fastening member (9)
a first clamping portion (91) having a recess (91A) that opens toward the inside in the radial direction of the variable nozzle unit (6) and clamps an outer peripheral edge portion (76, 77) of the first plate portion (71);
a second clamping portion (92) having a recess (92) opening toward the inside in the radial direction and clamping an outer peripheral edge portion (84) of the second plate portion (81);
The clamping portion includes a plate-shaped connecting portion (93) having one end connected to the first clamping portion (91) and the other end connected to the second clamping portion (92).

According to the configuration of 1) above, the fastening member (9) can fasten the first plate-shaped member (7) and the second plate-shaped member (8) so as to form the first gap (G) by clamping the outer peripheral edge portion (76, 77) of the first plate portion (71) with the first clamping portion (91) and clamping the outer peripheral edge portion (84) of the second plate portion (81) with the second clamping portion (92). In this case, since no laborious process such as crimping or welding is required when fastening the first plate-shaped member (7) and the second plate-shaped member (8), the assembly of the variable nozzle unit (6) can be improved compared to the case where a conventional nozzle support is used to fasten the first plate-shaped member (7) and the second plate-shaped member (8).

In addition, according to the configuration of 1) above, since the connection portion (93) of the fastening member (9) is plate-shaped, its rigidity can be reduced compared to that of conventional nozzle supports. By reducing the rigidity of the connection portion (93), it is possible to reduce the stress generated in the connection portion (93) due to the thermal expansion difference between the first plate-shaped member (7) and the second plate-shaped member (8) when the variable nozzle unit (6) is thermally deformed, and it is possible to suppress damage to the connection portion (93) when the variable nozzle unit (6) is thermally deformed.

2) In some embodiments, the variable nozzle unit (6) according to 1) above,
The first clamping portion (91) is
a pair of first clamping pieces (94, 95) that clamp a first flow path surface (72) that forms the gas flow path (43A) of the first plate portion (71) and a first back surface (73) opposite to the first flow path surface (72);
a first connecting piece (96) that connects the outer circumferential ends of the pair of first clamping pieces (94, 95),
The second clamping portion (92) is
a pair of second clamping pieces (97, 98) that clamp a second flow path surface (82) that forms the gas flow path (43A) of the second plate portion (81) and a second back surface (83) opposite to the second flow path surface (82);
and a second connecting piece (99) that connects the outer circumferential ends of the pair of second clamping pieces (97, 98) to each other.

According to the above configuration 2), the first connecting piece (96) applies an elastic force to the pair of first clamping pieces (94, 95) in the clamping direction, so that the first clamping portion (91) can firmly clamp the first plate portion (71). The second connecting piece (99) applies an elastic force to the pair of second clamping pieces (97, 98) in the clamping direction, so that the second clamping portion (92) can firmly clamp the second plate portion (81). Therefore, the fastening member (9) can firmly fasten the first plate member (7) and the second plate member (8). The first clamping portion (91) can move in the radial direction in accordance with the thermal expansion of the first plate member (7) when the first plate member (7) is thermally deformed in the radial direction, and the second clamping portion (92) can move in the radial direction in accordance with the thermal expansion of the second plate member (8) when the second plate member (8) is thermally deformed in the radial direction. This can reduce the stress generated in the connection portion (93) when the variable nozzle unit (6) is thermally deformed.

3) In some embodiments, the variable nozzle unit (6) according to 2) above,
Of the pair of first clamping pieces (94, 95), the first outer clamping piece (94) facing the first back surface (73) is inclined toward the one side in the axial direction as it moves inward in the radial direction from the first connecting piece (96),
The first back surface (73) facing the first outer clamping piece (94) includes a first inclined surface (731) that inclines toward the one side in the axial direction as it moves inward in the radial direction and engages the first outer clamping piece (94).

According to the configuration of 3) above, by engaging the first outer clamping piece (94) with the first inclined surface (731) of the first plate portion (71), the first outer clamping piece (94) becomes difficult to remove from the first plate portion (71), and therefore, the first outer clamping piece (94) can be prevented from falling off the first plate portion (71).

4) In some embodiments, the variable nozzle unit (6) according to 2) or 3) above,
Of the pair of second clamping pieces (97, 98), the second outer clamping piece (97) facing the second back surface (83) is inclined toward the other side in the axial direction as it moves inward in the radial direction from the second connecting piece (99),
The second back surface (83) facing the second outer clamping piece (97) includes a second inclined surface (831) that inclines toward the other side in the axial direction as it moves inward in the radial direction, and against which the second outer clamping piece (97) is engaged.

According to the configuration of 4) above, by engaging the second outer clamping piece (97) with the second inclined surface (831) of the second plate portion (81), the second outer clamping piece (97) becomes difficult to remove from the second plate portion (81), and therefore, the second outer clamping piece (97) can be prevented from falling off the second plate portion (81).

5) In some embodiments, the variable nozzle unit (6) according to any one of 2) to 4) above,
The first back surface (73) facing the first outer clamping piece (94) further includes a first opposing surface (733) facing the first outer clamping piece (94) via a gap (G1) on the outer side of the first inclined surface (731) in the radial direction.

According to the configuration of 5) above, by providing the first opposing surface (733) facing the first outer clamping piece (94) via the gap (G1), it is easier to engage the first outer clamping piece (94) with the first inclined surface (731) than when the first opposing surface (733) is not provided, and therefore it is easier to attach the first clamping portion (91) to the first plate portion (71). This further improves the ease of assembly of the variable nozzle unit (6).

6) In some embodiments, the variable nozzle unit (6) described in 5) above,
The first opposing surface (733) is inclined toward the one side in the axial direction from the outer circumferential end (732) of the first inclined surface (731) toward the outside in the radial direction.

According to the configuration of 6) above, when the first clamping part (91) is attached to the first plate part (71), the tip (the inner end in the radial direction) of the first outer clamping piece (94) comes into contact with the first opposing surface (733) and opens toward the first connecting piece (96), making it easier to attach the first clamping part (91) to the first plate part (71). This further improves the ease of assembly of the variable nozzle unit (6).

7) In some embodiments, the variable nozzle unit (6) according to any one of 3) to 6) above,
The first outer clamping piece (94) has a barb (941) at an inner end in the radial direction, the barb being inclined toward the other side in the axial direction as it moves inward in the radial direction.

According to the configuration of 7) above, by providing a barb (941) at the tip (the inner end in the radial direction) of the first outer clamping piece (94), the frictional resistance between the first outer clamping piece (94) and the first plate portion (71) can be reduced, making it easier to attach the first clamping portion (91) to the first plate portion (71). This further improves the ease of assembly of the variable nozzle unit (6).

8) In some embodiments, the variable nozzle unit (6) according to any one of 2) to 7) above,
The connection portion (93) is
The one end is connected to an inner end in the radial direction of a first inner clamping piece (95) that faces the first flow path surface (72) of the pair of first clamping pieces (94, 95),
The other end is connected to an inner end in the radial direction of a second inner clamping piece (98) that faces the second flow path surface (82) out of the pair of second clamping pieces (97, 98).

According to the configuration of 8) above, the structure of the fastening member (9) is simplified, and by performing bending processing or the like on a single plate-like member, the fastening member (9) having the first clamping portion (91), the second clamping portion (92), and the connecting portion (93) can be formed. In this case, the fastening member (9) is relatively lightweight and easy to manufacture, and therefore the cost (material cost and manufacturing cost) of the fastening member (9) can be kept low.

9) In some embodiments, the variable nozzle unit (6) according to any one of 1) to 8) above,
The connecting portion (93) has, in at least a portion of a cross section perpendicular to the axial direction, a bent portion (931) that is convex toward the outside or inside in the radial direction and extends along the axial direction.

According to the configuration of 9) above, by providing the connection portion (93) with a bent portion (931) extending along the axial direction, it is possible to suppress the occurrence of buckling of the connection portion (93) when a load acts on the connection portion (93) along the axial direction of the variable nozzle unit (6). By suppressing the occurrence of buckling of the connection portion (93), it is possible to maintain the first gap (G) at a predetermined interval, and therefore it is possible to suppress malfunction of the variable nozzle vane (61) due to a reduction in the first gap (G).

10) In some embodiments, the variable nozzle unit (6) according to any one of 1) to 8) above,
The connection portion (93) is curved toward either the outside or the inside in the radial direction in a cross section perpendicular to the axial direction.

According to the configuration of 10) above, by curving the connection portion (93) toward either the outside or inside in the radial direction in a cross section perpendicular to the axial direction, it is possible to suppress the occurrence of buckling of the connection portion (93) when a load acts on the connection portion (93) along the axial direction of the variable nozzle unit (6). By suppressing the occurrence of buckling of the connection portion (93), the first gap (G) can be maintained at a predetermined distance, and therefore malfunction of the variable nozzle vane (61) due to a reduction in the first gap (G) can be suppressed.

11) In some embodiments, the variable nozzle unit (6) according to any one of 1) to 10) above,
In the circumferential direction of the variable nozzle unit (6), the side where the leading edge (611) is located relative to the trailing edge (612) of the variable nozzle vane (61) is defined as the upstream side, and the side where the trailing edge (612) is located relative to the leading edge (611) is defined as the downstream side.
The connection portion (93) is inclined so that, in a cross section perpendicular to the axial direction, the downstream end portion (932) is positioned radially inward relative to the upstream end portion (933).

According to the configuration of 11) above, the connection portion (93) is inclined so that its downstream end portion (932) is positioned radially inward relative to its upstream end portion (933), thereby straightening the flow of gas toward the variable nozzle vane (61) and smoothing the flow of gas into the variable nozzle vane (61), thereby improving the performance of the turbine (2) equipped with the variable nozzle unit (6).

12) In some embodiments, the variable nozzle unit (6) according to 11) above,
The at least one variable nozzle vane (61) includes a plurality of variable nozzle vanes (61) arranged at different circumferential positions spaced apart from each other in the circumferential direction,
The at least one fastening member (9) is configured such that a straight line (SL) extending from the downstream end (932) of the connection portion (93) passes upstream of the midpoint (CP) of the rotation axes (RC) of two variable nozzle vanes (61) adjacent to the fastening member (9) in the circumferential direction on a virtual circle (VC) passing through the rotation axes (RC) of each of the plurality of variable nozzle vanes (61).

According to the configuration of 12) above, the gas flow toward the variable nozzle vane (61) straightened by the connection portion (93) passes upstream of the intermediate position (CP) between two adjacent variable nozzle vanes (61) in the circumferential direction relative to the fastening member (9). In this case, the gas can flow smoothly into the multiple variable nozzle vanes (61), thereby improving the performance of the turbine (2) equipped with the variable nozzle unit (6).

13) The turbine (2) according to at least one embodiment of the present disclosure comprises:
The variable nozzle unit (6) is provided as described in any one of 1) to 12) above.

According to the configuration of 13) above, damage to the variable nozzle unit (6) during thermal deformation can be suppressed, thereby improving the reliability of the turbine (2) equipped with the variable nozzle unit (6).

14) A turbocharger (1) according to at least one embodiment of the present disclosure,
A turbine (2) according to the above 13),
and a centrifugal compressor (12) configured to be driven by the turbine (2).

According to the configuration of 14) above, damage to the variable nozzle unit (6) during thermal deformation can be suppressed, thereby improving the reliability of the turbocharger (1) equipped with the variable nozzle unit (6).

1 turbocharger 2 turbine 3 turbine wheel 4 first housing 5 second housing 6 variable nozzle unit 7 first plate-shaped member 8 second plate-shaped member 9 fastening member 10 internal combustion engine system 11 internal combustion engine 12 centrifugal compressor 13 impeller 14 compressor housing 15 rotating shaft 16 bearing 21 biasing member 21A disc spring 31 hub 32 turbine blade 41 scroll passage 42 exhaust gas discharge passage 43 internal space 43A gas passage 43B first space 61 variable nozzle vane 62 annular member 63 link member 65 drive mechanism 71 first plate portion 72 first passage surface 73 first back surface 74 through hole 75 inner peripheral edge portion 76 outer peripheral edge portion 77 concave groove 81 second plate portion 82 second passage surface 83 second back surface 91 first clamping portion 92 second clamping portion 93 connection portion 94 first outer clamping piece 95 First inner clamping piece 96 First connecting piece 97 Second outer clamping piece 98 Second inner clamping piece 99 Second connecting piece CP Intermediate position G First gap G1, G2 Gaps LA, LC Axis line P1 Rear end RC Rotation axis SL Straight line VC Virtual circle

Claims (14)

A variable nozzle unit that is mounted on a turbine and is configured to be able to vary a flow passage area of gas supplied to a turbine wheel,
A first plate-shaped member including an annular first plate portion;
a second plate member including an annular second plate portion that forms a gas flow path between itself and the first plate portion, the second plate portion being disposed opposite to the first plate portion on one side of the first plate portion in the axial direction of the variable nozzle unit;
at least one variable nozzle vane provided in the gas flow passage and rotatably supported by the first plate-shaped member or the second plate-shaped member;
at least one fastening member fastening the first plate member and the second plate member to form a first gap between the first plate portion and the second plate portion;
The at least one fastening member is
a first clamping portion having a recess that opens toward an inner side in a radial direction of the variable nozzle unit and clamps an outer circumferential edge portion of the first plate portion;
a second clamping portion having a recess that opens toward the inside in the radial direction and clamps an outer peripheral edge portion of the second plate portion;
a plate-shaped connecting portion having one end connected to the first clamping portion and the other end connected to the second clamping portion. The first clamping unit is
a pair of first clamping pieces that clamp a first flow path surface that forms the gas flow path of the first plate portion and a first back surface that is opposite to the first flow path surface;
a first connecting piece that connects outer peripheral ends of the pair of first clamping pieces,
The second clamping unit is
a pair of second clamping pieces that clamp a second flow path surface that forms the gas flow path of the second plate portion and a second back surface that is opposite to the second flow path surface;
A second connecting piece that connects the outer circumferential ends of the pair of second clamping pieces together.
The variable nozzle unit according to claim 1 . Of the pair of first clamping pieces, a first outer clamping piece facing the first back surface is inclined toward the one side in the axial direction as it moves inward in the radial direction from the first connecting piece,
The first back surface facing the first outer clamping piece includes a first inclined surface that is inclined toward the one side in the axial direction as it moves toward the inside in the radial direction and is engaged with the first outer clamping piece.
The variable nozzle unit according to claim 2 . Of the pair of second clamping pieces, a second outer clamping piece facing the second back surface is inclined toward the other side in the axial direction as it moves inward in the radial direction from the second connecting piece,
The second back surface facing the second outer clamping piece includes a second inclined surface that is inclined toward the other side in the axial direction as it moves toward the inside in the radial direction and is engaged with the second outer clamping piece.
The variable nozzle unit according to claim 3 . The first back surface facing the first outer clamping piece further includes a first opposing surface facing the first outer clamping piece via a gap, the first opposing surface being located outside the first inclined surface in the radial direction.
The variable nozzle unit according to claim 3 . The first opposing surface is inclined toward the one side in the axial direction from an outer circumferential end of the first inclined surface toward an outer side in the radial direction.
The variable nozzle unit according to claim 5. A barb is provided at an inner end portion in the radial direction of the first outer clamping piece, the barb being inclined toward the other side in the axial direction as it moves toward the inside in the radial direction.
The variable nozzle unit according to any one of claims 3 to 6. The connection portion is
The one end is connected to an inner end in the radial direction of a first inner clamping piece of the pair of first clamping pieces that faces the first flow path surface,
The other end is connected to an inner end in the radial direction of a second inner clamping piece that faces the second flow path surface of the pair of second clamping pieces.
The variable nozzle unit according to any one of claims 2 to 6. The connection portion has a bent portion that is convex toward the outside or inside in the radial direction in at least a part of a cross section perpendicular to the axial direction and extends along the axial direction.
The variable nozzle unit according to any one of claims 1 to 6. The connection portion is curved toward either the outside or the inside in the radial direction in a cross section perpendicular to the axial direction.
The variable nozzle unit according to any one of claims 1 to 6. In the circumferential direction of the variable nozzle unit, a side where a leading edge is located relative to a trailing edge of the variable nozzle vane is defined as an upstream side, and a side where the trailing edge is located relative to the leading edge is defined as a downstream side,
the connection portion is inclined such that the downstream end portion is located radially inward relative to the upstream end portion in a cross section perpendicular to the axial direction.
The variable nozzle unit according to any one of claims 1 to 6. the at least one variable nozzle vane includes a plurality of variable nozzle vanes arranged at different circumferential positions spaced apart from one another in the circumferential direction,
the at least one fastening member is configured such that a straight line extending from an end portion on the downstream side of the connection portion passes upstream of a middle position of the rotation axes of two variable nozzle vanes adjacent to the fastening member in the circumferential direction in a virtual circle passing through the rotation axes of each of the plurality of variable nozzle vanes.
The variable nozzle unit according to claim 11. A turbine equipped with a variable nozzle unit according to any one of claims 1 to 6. A turbine according to claim 13;
a centrifugal compressor configured to be driven by the turbine;
A turbocharger comprising:

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