JP7052263B2 - Variable nozzle turbocharger - Google Patents

Description

The present invention relates to a variable nozzle turbocharger.

Conventionally, a variable nozzle turbocharger is known as a turbocharger that supercharges intake air by using the energy of the exhaust gas of an engine (see, for example, Patent Document 1). Specifically, Patent Document 1 describes a nozzle ring that defines a scroll flow path that introduces the exhaust of the turbine scroll portion into the turbine, a variable nozzle (nozzle vane) arranged in the scroll flow path, and the variable nozzle. A variable nozzle turbocharger (variable capacity turbocharger) including a nozzle shaft which is a rotating shaft is disclosed. The nozzle shaft of this variable nozzle is inserted into a nozzle shaft hole provided in the nozzle ring, and is rotatably supported by the nozzle shaft hole.

International Publication No. 2016/159004

In the variable nozzle turbocharger as described above, since the diameter of the nozzle shaft hole is larger than the diameter of the nozzle shaft, it is between the inner peripheral surface of the nozzle shaft hole and the outer peripheral surface of the nozzle shaft facing the inner peripheral surface. There is a gap. Therefore, a part of the exhaust gas of the scroll flow path may leak into this gap. In this case, the flow rate of the exhaust gas flowing into the turbine decreases, so that the turbine efficiency of the variable nozzle turbocharger decreases.

The present invention has been made in view of the above, and an object of the present invention is to provide a variable nozzle turbocharger capable of improving turbine efficiency.

In order to achieve the above object, the variable nozzle turbocharger according to the present invention includes a nozzle ring defining a scroll flow path for introducing the exhaust of the turbine scroll portion into the turbine, a variable nozzle arranged in the scroll flow path, and a variable nozzle. In a variable nozzle turbocharger comprising a nozzle shaft which is a rotation shaft of the variable nozzle and having the nozzle shaft inserted into a nozzle shaft hole provided in the nozzle ring, the nozzle shaft hole has the nozzle shaft. A shaft support hole portion that supports the shaft, a large-diameter hole portion that is arranged at the end of the nozzle shaft hole on the side of the scroll flow path and has a larger diameter than the shaft support hole portion, and the above- mentioned The variable nozzle turbocharger has a step portion that faces the nozzle shaft hole in the axial direction at the boundary portion between the shaft support hole portion and the large diameter hole portion, and the variable nozzle turbocharger is fitted to the nozzle shaft and the large diameter hole. A sealing member composed of a flat plate-shaped ring member housed in the portion is provided , and the sealing member seals the inner peripheral hole of the sealing member and the gap on the outer peripheral surface of the nozzle shaft in a non-contact manner. It is characterized in that it receives the pressure of the exhaust and comes into contact with the step portion .
In order to achieve the above object, the variable nozzle turbocharger according to the present invention includes a nozzle ring defining a scroll flow path for introducing the exhaust of the turbine scroll portion into the turbine, a variable nozzle arranged in the scroll flow path, and a variable nozzle. In a variable nozzle turbocharger comprising a nozzle shaft which is a rotation shaft of the variable nozzle and having the nozzle shaft inserted into a nozzle shaft hole provided in the nozzle ring, the nozzle shaft hole has the nozzle shaft. A shaft support hole portion that supports the shaft, a large-diameter hole portion that is arranged at the end of the nozzle shaft hole on the side of the scroll flow path and has a larger diameter than the shaft support hole portion, and the shaft. The variable nozzle turbocharger has a step portion facing the axial direction of the nozzle shaft hole at the boundary portion between the support hole portion and the large diameter hole portion, and the variable nozzle turbocharger is fitted to the nozzle shaft and the large diameter hole portion. A sealing member accommodated in a conical shape that expands in diameter from the variable nozzle toward the axis of the nozzle shaft and generates a force opposed to the compressive force when a compressive force is applied in the thickness direction. When the compression force is applied by receiving the pressure of the exhaust, the seal member enhances the degree of adhesion between the inner peripheral hole of the seal member and the outer peripheral surface of the nozzle shaft, and the outer peripheral edge of the seal member. It is characterized by increasing the degree of adhesion of the stepped portion.

According to the present invention, due to the sealing member housed in the large-diameter hole portion of the nozzle ring, the exhaust of the scroll flow path is the inner peripheral surface of the shaft support hole portion of the nozzle shaft hole and the nozzle shaft facing the inner peripheral surface. Leakage to the gap with the outer peripheral surface can be suppressed. Therefore, the turbine efficiency can be improved.

It is a schematic sectional drawing which shows typically the structure of the variable nozzle turbocharger which concerns on embodiment. 2 (a) and 2 (c) are views for explaining the variable nozzle unit according to the embodiment. 3A to 3D are diagrams for explaining a variable nozzle unit according to a modified example of the embodiment.

(Embodiment)
Hereinafter, the variable nozzle turbocharger 1 according to the embodiment will be described with reference to the drawings. It should be noted that the drawings are schematically shown schematically so that the configuration is easy to understand, and the dimensional ratios of each part on the drawings do not always match the actual ones. FIG. 1 is a schematic cross-sectional view schematically showing the configuration of the variable nozzle turbocharger 1 according to the present embodiment. Note that FIG. 1 schematically shows a cross section of one side of the variable nozzle turbocharger 1 with respect to the turbo axis 6 (this is the axis of the turbo shaft 4 described later). Further, FIG. 1 is provided with Cartesian coordinates of XYZ for reference. This Y-axis is an axis parallel to the turbo axis 6.

The variable nozzle turbocharger 1 is connected to the engine of the vehicle via pipes such as an exhaust pipe and an intake pipe. As an example of this engine, a diesel engine is used in this embodiment. The variable nozzle turbocharger 1 includes a turbine 2, a compressor 3, a turbo shaft 4, a turbo bearing 5, a turbine housing 7, a compressor housing 8, a bearing housing 9, and a variable nozzle unit 20.

The turbine 2 and the compressor 3 are connected by a turbo shaft 4. The turbine 2 is composed of a turbine impeller having a plurality of turbine blades. The compressor 3 is composed of a compressor impeller having a plurality of compressor blades. The turbo bearing 5 is a bearing that supports the turbo shaft 4 and is housed in the bearing housing 9.

The turbine housing 7 houses the turbine 2 inside. The compressor housing 8 houses the compressor 3 inside. The turbine housing 7 is provided with a turbine scroll portion 10 and an exhaust outlet 11. The compressor housing 8 is provided with an intake inlet 12 and a compressor scroll portion 13. The exhaust (E) discharged from the engine flows into the turbine scroll portion 10, then comes into contact with the turbine 2, and then is discharged from the exhaust outlet 11. The intake air (A) on the upstream side of the variable nozzle turbocharger 1 flows into the intake air inlet 12 of the compressor housing 8.

The turbine 2 receives the energy of the exhaust gas flowing in from the turbine scroll portion 10 and rotates about the turbo axis 6 as the center of rotation. When the turbine 2 rotates, the compressor 3 connected to the turbine 2 via the turbo shaft 4 also rotates. As the compressor 3 rotates, the compressor 3 supercharges the intake air. This supercharged intake air is discharged from the compressor scroll unit 13 and supplied to the engine. In this way, the variable nozzle turbocharger 1 supercharges the intake air by utilizing the energy of the exhaust gas.

Subsequently, the variable nozzle unit 20 will be described. FIG. 2A is a schematic enlarged cross-sectional view schematically showing an enlarged part of the variable nozzle unit 20 of the variable nozzle turbocharger 1. With reference to FIGS. 1 and 2A, the variable nozzle unit 20 includes a pair of nozzle rings (first nozzle ring 21 and second nozzle ring 22), a variable nozzle 30, a nozzle shaft 40, and a variable nozzle. It includes a drive mechanism 80 and a seal washer 50 as an example of a seal member.

The first nozzle ring 21 and the second nozzle ring 22 are each composed of a ring-shaped member having a turbo axis 6 as a central axis. Specifically, the first nozzle ring 21 and the second nozzle ring 22 are composed of ring-shaped members that surround the turbine 2.

A scroll flow path 23 is defined between the facing surface of the first nozzle ring 21 facing the second nozzle ring 22 and the facing surface of the second nozzle ring 22 facing the first nozzle ring 21. The scroll flow path 23 is an internal exhaust flow path for introducing the exhaust gas of the turbine scroll portion 10 into the turbine 2.

The variable nozzle 30 is arranged in the turbine scroll portion 10. Although only one variable nozzle 30 is shown in FIGS. 1 and 2, the variable nozzle unit 20 actually includes a plurality of variable nozzles 30. Specifically, a plurality of variable nozzles 30 are arranged in a circumferential shape with the turbo axis 6 as the central axis while having a predetermined interval between the variable nozzles 30 and the adjacent variable nozzles 30.

The nozzle shaft 40 is a rotation shaft of the variable nozzle 30. Note that FIG. 2A shows the nozzle axis 41, which is the axis of the nozzle axis 40. Each variable nozzle 30 rotates with the nozzle axis 41 as the center of rotation. The nozzle axis 41 according to the present embodiment is an axis parallel to the Y axis of Cartesian coordinates of XYZ.

With reference to FIG. 1, the variable nozzle drive mechanism 80 is a rotation drive mechanism for rotating the variable nozzle 30 (note that in FIG. 1, illustration of each component of the variable nozzle drive mechanism 80 is omitted. ). The variable nozzle drive mechanism 80 is arranged in the variable nozzle drive chamber 14 provided in the bearing housing 9. The variable nozzle drive mechanism 80 is connected to an end portion (end portion on the Y direction side) of the nozzle shaft 40 opposite to the scroll flow path 23 side, and the variable nozzle 30 is formed by rotating the nozzle shaft 40. To rotate. As the variable nozzle drive mechanism 80, for example, a known variable nozzle drive mechanism used in a known variable nozzle turbocharger as exemplified in Patent Document 1 can be applied, and thus the details thereof. The description of the configuration is omitted.

The rotation of each variable nozzle 30 by the variable nozzle drive mechanism 80 changes the distance between the variable nozzles 30 adjacent to each other (this distance is generally referred to as a vane distance). When the vane interval is narrowed, the exhaust gas of the scroll flow path 23 is throttled, so that the exhaust flow velocity that passes through the scroll flow path 23 and flows into the turbine 2 increases. As a result, the rotational speed of the turbine 2 can be increased. In this way, the variable nozzle turbocharger 1 can adjust the rotation speed of the turbine 2 by adjusting the rotation angle of the variable nozzle 30.

FIG. 2B is a schematic enlarged cross-sectional view of the first nozzle ring 21 and the second nozzle ring 22 of the variable nozzle unit 20 of FIG. 2A. FIG. 2C is a schematic enlarged cross-sectional view of the variable nozzle unit 20 of FIG. 2A, which is an excerpt of the variable nozzle 30, the nozzle shaft 40, and the seal washer 50.

As shown in FIGS. 2A and 2C, the nozzle shaft 40 according to the present embodiment is composed of a shaft body portion 42 having a uniform outer diameter. Further, a seal washer 50 (that is, a seal member) is fitted in the shaft main body portion 42 of the nozzle shaft 40. Specifically, the seal washer 50 according to the present embodiment is composed of a flat plate-shaped ring member. The inner peripheral hole 52 (hole on the inner peripheral side of the ring) of the seal washer 50 is fitted to the outer peripheral surface 43 of the shaft main body portion 42.

As shown in FIG. 2B, the first nozzle ring 21 is provided with a nozzle shaft hole 60. The nozzle shaft hole 60 according to the present embodiment is configured by a through hole penetrating in the direction of the nozzle axis 41 (direction along the Y axis). The nozzle shaft 40 described above is inserted through the nozzle shaft hole 60.

Specifically, the nozzle shaft hole 60 has a shaft support hole portion 61 that rotatably supports the nozzle shaft 40, and a large diameter hole portion 62 having a diameter larger than that of the shaft support hole portion 61. There is. The large-diameter hole portion 62 is provided at the end of the nozzle shaft hole 60 on the scroll flow path 23 side (the end of the nozzle shaft hole 60 on the −Y direction side). The shaft support hole portion 61 is connected to the end portion of the large diameter hole portion 62 on the Y direction side. As a result, the nozzle shaft hole 60 has a stepped portion 63 at the boundary portion between the large diameter hole portion 62 and the shaft support hole portion 61.

The diameter of the shaft support hole portion 61 is set to be slightly larger than the diameter of the shaft main body portion 42 of the nozzle shaft 40. As a result, when the nozzle shaft 40 rotates, the outer peripheral surface 43 of the shaft main body portion 42 of the nozzle shaft 40 rotates while sliding on the inner peripheral surface 64 of the shaft support hole portion 61.

The diameter of the large-diameter hole portion 62 is set to be larger than the outer diameter of the seal washer 50. The seal washer 50 fitted to the nozzle shaft 40 is housed in the large-diameter hole portion 62 so as not to protrude into the scroll flow path 23. Specifically, the thickness of the seal washer 50 (the length in the direction of the nozzle axis 41) according to the present embodiment is set to be equal to or less than the thickness of the large-diameter hole portion 62, whereby the seal washer 50 is −Y. The end surface on the direction side is set so as not to protrude into the scroll flow path 23 (in other words, so as not to protrude toward the −Y direction side from the end surface on the −Y direction side of the first nozzle ring 21).

The seal washer 50 housed in the large-diameter hole portion 62 has an inner peripheral surface 64 of the shaft support hole portion 61 of the nozzle shaft hole 60 and an outer peripheral surface 43 of the nozzle shaft 40 facing the inner peripheral surface 64. The gap is sealed.

Specifically, the gap between the inner peripheral hole 52 of the seal washer 50 and the outer peripheral surface 43 of the shaft main body 42 of the nozzle shaft 40 according to the present embodiment is such that the exhaust of the scroll flow path 23 does not easily pass through this gap. It is set to a small amount. Therefore, due to the labyrinth effect due to this gap, the exhaust gas of the scroll flow path 23 passes through this gap and becomes the inner peripheral surface 64 of the shaft support hole portion 61 and the outer peripheral surface 43 of the nozzle shaft 40 facing the inner peripheral surface 64. Leakage into the gap is suppressed.

Further, the seal washer 50 is pressed in the Y direction by receiving the exhaust pressure of the scroll flow path 23, so that the seal washer 50 comes into contact with the step portion 63 of the nozzle shaft hole 60. As a result, the gap between the seal washer 50 and the step portion 63 becomes substantially zero. Further, the gap between the inner peripheral surface 65 of the large-diameter hole portion 62 and the outer peripheral surface 51 of the seal washer 50 is set to be minute so that the exhaust gas of the scroll flow path 23 does not easily flow into this gap. Therefore, due to the labyrinth effect due to these gaps, the exhaust of the scroll flow path 23 becomes the gap between the inner peripheral surface 65 of the large-diameter hole portion 62 and the outer peripheral surface 51 of the seal washer 50, and the seal washer 50 and the step portion 63. Leakage to the gap between the inner peripheral surface 64 of the shaft support hole 61 and the outer peripheral surface 43 of the shaft main body 42 of the nozzle shaft 40 facing the inner peripheral surface 64 is also suppressed.

That is, according to the present embodiment, the labyrinth seal structure is formed by the seal washer 50 housed in the large-diameter hole portion 62, whereby the exhaust of the scroll flow path 23 is discharged from the shaft support hole portion of the nozzle shaft hole 60. Leakage to the gap between the inner peripheral surface 64 of 61 and the outer peripheral surface 43 of the nozzle shaft 40 facing the inner peripheral surface 64 is suppressed.

As shown in FIGS. 2 (a) and 2 (c), the shaft main body 42 of the nozzle shaft 40 according to the present embodiment has a structure that protrudes further toward the −Y direction than the variable nozzle 30. There is. Therefore, as shown in FIG. 2B, a nozzle shaft into which a portion of the shaft main body 42 protruding in the −Y direction from the variable nozzle 30 is inserted into the second nozzle ring 22 according to the present embodiment. The holes 70 are formed. If the shaft main body 42 does not have a portion protruding in the −Y direction from the variable nozzle 30, the nozzle shaft hole 70 of the second nozzle ring 22 is unnecessary.

Subsequently, the action and effect of this embodiment will be described. First, as a comparative example, a variable nozzle turbocharger having no seal washer 50 and a large-diameter hole portion 62 is assumed. In the case of the variable nozzle turbocharger according to this comparative example, a part of the exhaust gas of the scroll flow path is a gap between the inner peripheral surface of the shaft support hole portion of the nozzle shaft hole and the outer peripheral surface of the nozzle shaft facing the inner peripheral surface. May leak to. In this case, the flow rate of the exhaust gas flowing into the turbine is reduced by the amount of the leaked exhaust gas, so that the turbine efficiency of the variable nozzle turbocharger is lowered. Specifically, in the case of the comparative example, the turbine efficiency is lowered especially in the low speed range.

On the other hand, according to the variable nozzle turbocharger 1 according to the present embodiment, the exhaust of the scroll flow path 23 is exhausted by the shaft support hole portion 61 of the nozzle shaft hole 60 by the seal washer 50 accommodated in the large diameter hole portion 62. It is possible to suppress leakage to the gap between the inner peripheral surface 64 and the outer peripheral surface 43 of the nozzle shaft 40 facing the inner peripheral surface 64. Further, since the seal washer 50 is housed in the large-diameter hole portion 62 so as not to protrude into the scroll flow path 23, the seal washer 50 protruding from the scroll flow path 23 hinders the flow of exhaust gas from the scroll flow path 23. It is also suppressed. Therefore, according to the present embodiment, the turbine efficiency can be improved. In particular, turbine efficiency in the low speed range can be improved.

In the present embodiment, the seal washer 50 is housed in the large-diameter hole portion 62 so as not to protrude into the scroll flow path 23, but the present invention is not limited to this configuration. A part of the seal washer 50 may protrude into the scroll flow path 23. Even in this case, due to the sealing function of the seal washer 50, the exhaust of the scroll flow path 23 is the inner peripheral surface 64 of the shaft support hole portion 61 of the nozzle shaft hole 60 and the outer peripheral surface 43 of the nozzle shaft 40 facing the inner peripheral surface 64. It is possible to suppress leakage to the gap between the two. However, as in the present embodiment, when the seal washer 50 is housed in the large-diameter hole portion 62 so as not to protrude into the scroll flow path 23, the seal washer 50 protruding from the scroll flow path 23 causes the seal washer 50. Turbine efficiency can be effectively improved in that the flow of the exhaust air of the scroll flow path 23 can be suppressed from being obstructed. In this respect, it is preferable that the seal washer 50 does not protrude into the scroll flow path 23.

(Modified example of the embodiment)
Subsequently, the variable nozzle turbocharger 1a according to the modified example of the above-described embodiment will be described. The variable nozzle turbocharger 1a according to the present modification is different from the variable nozzle turbocharger 1 according to the above-described embodiment in that the variable nozzle unit 20a is provided in place of the variable nozzle unit 20. FIG. 3A is a schematic enlarged cross-sectional view schematically showing an enlarged part of the variable nozzle unit 20a according to the present modification. FIG. 3B is a schematic enlarged cross-sectional view of the first nozzle ring 21 and the second nozzle ring 22 of the variable nozzle unit 20a of FIG. 3A. FIG. 3C is a schematic enlarged cross-sectional view of the variable nozzle unit 20a of FIG. 3A, which is an excerpt of the variable nozzle 30, the nozzle shaft 40, and the seal washer 50a. FIG. 3D is a schematic perspective view of the seal washer 50a.

The variable nozzle unit 20a according to the present modification is different from the variable nozzle unit 20 according to the above-described embodiment in that the seal washer 50a is provided instead of the seal washer 50 as an example of the seal member. The seal washer 50a is a seal washer that generates a force that opposes the compressive force when a compressive force is applied in the thickness direction of the seal washer 50a.

The specific shape of the seal washer 50a is not particularly limited as long as it has such a function, but the seal washer 50a according to this modification is, as an example, the center in the radial direction of the seal washer 50a. The portion is composed of a conical countersunk spring type seal washer having a portion protruding to one side (specifically, the −Y direction side) with respect to the outer peripheral portion of the seal washer 50a (FIGS. 3 (c) and 3). (D)). In this case, when a compressive force is applied in the thickness direction (direction along the Y axis) of the seal washer 50a, the seal washer 50a generates a force (specifically, a spring force) that opposes the compressive force.

According to this modification, the following effects can be obtained in addition to the effects of the above-described embodiment. Specifically, when a compressive force is applied to the seal washer 50a by the pressure of the exhaust of the scroll flow path 23, the degree of adhesion between the inner peripheral hole 52 of the seal washer 50a and the nozzle shaft 40 can be increased. It is also possible to increase the degree of adhesion between the outer peripheral edge 53 of the seal washer 50a and the stepped portion 63 of the nozzle shaft hole 60. As a result, the exhaust of the scroll flow path 23 passes through the gap between the inner peripheral hole 52 of the seal washer 50a and the nozzle shaft 40, and the gap between the outer peripheral edge 53 of the seal washer 50a and the stepped portion 63 of the nozzle shaft hole 60. Can be effectively suppressed. As a result, it is possible to effectively prevent the exhaust gas of the scroll flow path 23 from leaking into the gap between the inner peripheral surface 64 of the shaft support hole 61 and the outer peripheral surface 43 of the nozzle shaft 40 facing the inner peripheral surface 64. Therefore, the decrease in turbine efficiency can be effectively suppressed.

The seal washer 50a is assembled in a state where a compressive force is applied so as to be compressed by a predetermined amount in the thickness direction at the time of assembling to the nozzle shaft 40 and the large diameter hole portion 62 (that is, at the time of the manufacturing process). Is preferable. In this case, if a portion (for example, a groove) in which the inner peripheral hole 52 of the seal washer 50a is caught is formed on the outer peripheral surface 43 of the nozzle shaft 40, a compressive force is applied to the seal washer 50a. It is preferable in that it can be easily assembled to the nozzle shaft 40 and the large-diameter hole portion 62.

In this way, by assembling the seal washer 50a to the nozzle shaft 40 and the large-diameter hole portion 62 in a state where the compressive force is applied to the seal washer 50a, the spring force of the seal washer 50a can be constantly generated. The degree of adhesion between the inner peripheral hole 52 of the seal washer 50a and the nozzle shaft 40 can be improved, and the degree of adhesion between the outer peripheral edge 53 of the seal washer 50a and the stepped portion 63 of the nozzle shaft hole 60 can be improved. As a result, the leakage of the exhaust gas from the scroll flow path 23 can be effectively suppressed, so that the decrease in turbine efficiency can be effectively suppressed.

Further, as described above, when the seal washer 50a is assembled to the nozzle shaft 40 and the large-diameter hole portion 62 in a state where the compressive force is applied to the seal washer 50a, pressure pulsation (pressure) is tentatively applied to the exhaust of the scroll flow path 23. Even when fluctuation) occurs, the pressure pulsation causes the seal washer 50a to be displaced in the −Y direction (the seal washer 50a is lifted), so that the outer peripheral edge 53 of the seal washer 50a is separated from the step portion 63. It can be effectively suppressed. Also in this respect, the decrease in turbine efficiency can be effectively suppressed.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to such a specific embodiment, and various modifications and modifications are made within the scope of the gist of the present invention described in the claims. Is possible.

1,1a Variable nozzle turbocharger 2 Turbine 3 Compressor 10 Turbine scroll unit 20, 20a Variable nozzle unit 21 First nozzle ring 22 Second nozzle ring 23 Scroll flow path 30 Variable nozzle 40 Nozzle shaft 42 Shaft body 43 Outer peripheral surface 50, 50a Seal washer (seal member)
60 Nozzle shaft hole 61 Shaft support hole portion 62 Large diameter hole portion 63 Stepped portion 64 Inner peripheral surface

Claims (3)

The nozzle shaft is provided with a nozzle ring that defines a scroll flow path that introduces the exhaust of the turbine scroll portion into the turbine, a variable nozzle arranged in the scroll flow path, and a nozzle shaft that is a rotation axis of the variable nozzle. In the variable nozzle turbocharger inserted into the nozzle shaft hole provided in the nozzle ring.
The nozzle shaft hole is arranged at a shaft support hole portion that is a portion that pivotally supports the nozzle shaft and an end portion of the nozzle shaft hole on the scroll flow path side, and has a diameter larger than that of the shaft support hole portion. It has a large-diameter hole portion having a large diameter, and a step portion facing the nozzle shaft hole in the axial direction at the boundary portion between the shaft support hole portion and the large-diameter hole portion.
The variable nozzle turbocharger includes a sealing member made of a flat plate-shaped ring member that is fitted to the nozzle shaft and is accommodated in the large-diameter hole portion.
The seal member is a variable nozzle turbocharger characterized in that a gap between an inner peripheral hole of the seal member and an outer peripheral surface of the nozzle shaft is non-contactly sealed and is in contact with the step portion by receiving exhaust pressure. The nozzle shaft is provided with a nozzle ring that defines a scroll flow path that introduces the exhaust of the turbine scroll portion into the turbine, a variable nozzle arranged in the scroll flow path, and a nozzle shaft that is a rotation axis of the variable nozzle. In the variable nozzle turbocharger inserted into the nozzle shaft hole provided in the nozzle ring.
The nozzle shaft hole is arranged at a shaft support hole portion that is a portion that pivotally supports the nozzle shaft and an end portion of the nozzle shaft hole on the scroll flow path side, and has a diameter larger than that of the shaft support hole portion. It has a large-diameter hole portion having a large diameter, and a step portion facing the nozzle shaft hole in the axial direction at the boundary portion between the shaft support hole portion and the large-diameter hole portion.
The variable nozzle turbocharger is fitted in the nozzle shaft and is housed in the large-diameter hole portion, and has a conical shape that expands in diameter from the variable nozzle toward the axis of the nozzle shaft, and has a compressive force in the thickness direction. A sealing member that generates a force opposed to the compressive force when the is applied is provided.
When the compressive force is applied by receiving the exhaust pressure, the seal member enhances the degree of adhesion between the inner peripheral hole of the seal member and the outer peripheral surface of the nozzle shaft, and also increases the degree of adhesion to the outer peripheral edge of the seal member and the seal member. A variable nozzle turbocharger characterized by increasing the degree of adhesion of the stepped portion. The variable nozzle turbocharger according to claim 1 or 2, wherein the seal member is housed in the large-diameter hole portion so as not to protrude into the scroll flow path.

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