JP2010180811A - Variable displacement turbine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a variable displacement turbine capable of improving turbine efficiency, as a result of restraining reduction in the turbine efficiency due to a leakage flow, even if the leakage flow is generated. <P>SOLUTION: This variable displacement turbine has a nozzle 5 capable of increasing-decreasing a flow rate of gas introduced into a rotary vane 3. The variable displacement turbine is constituted so that the nozzle 5 has a pair of introducing walls of showing a substantially annular shape and a plurality of variable vanes 53 rotatably arranged between the pair of introducing walls, and has a projecting part 55 projecting toward the other introducing wall from at least one introducing wall 51 and positioned inside the movable vanes 53 in the radial direction of the introducing wall 51. The projecting part 55 adopts a constitution for displacing the flow direction of gas (the leakage flow) leaking out of a clearance between the variable vanes 53 and the one introducing wall 51 in the direction along the flow direction of the gas passing through openings S3 between the plurality of adjacent movable vanes. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

 The present invention relates to a turbine that rotates rotor blades by gas flow, and more particularly to a variable displacement turbine.

2. Description of the Related Art Conventionally, a turbine that rotates a rotor blade by the flow of exhaust gas (gas) of an engine is used for a turbocharger that supercharges air to the engine. The rotor blades of the turbine are connected to a centrifugal compressor, which supplies compressed air to the engine and improves engine performance. In addition, variable capacity turbines that can improve engine performance over a wide range from a low rotation range to a high rotation range are also used.
The variable capacity turbine has a pair of substantially annular introduction walls and a plurality of variable blades rotatably provided between the introduction walls. Openings are formed between a plurality of adjacent variable blades, and gas is introduced into the rotor blades through the openings. The variable capacity turbine can increase or decrease the flow rate of the gas introduced into the rotor blades by changing the direction of the variable blades and changing the size of the opening. In order to smoothly rotate the variable blade, a gap is appropriately provided between the variable blade and the introduction wall.

 By the way, since the said clearance gap is provided, some gas leaks from the said clearance gap. Since the leaked gas (leakage flow) flows in a direction different from the gas passing through the opening, it is difficult to use the flow of the leakage flow to rotate the rotor blades, and the leakage flow is a gas in the turbine. Loss is also caused by disturbing the flow. For this reason, the leakage flow lowers the efficiency of the turbine, and measures such as suppression of the leakage flow are required to further improve the turbine efficiency.

Here, Patent Document 1 discloses a variable blade for suppressing a leakage flow from the gap.
In the variable wing disclosed in Patent Document 1, the end faces of both ends of the variable wing facing the introduction wall are formed wider than the cross section of the central portion, and the end faces of both ends are formed in parallel with the introduction wall. Since both end surfaces of the variable blade have a larger area than that of the conventional variable blade, a large flow resistance is generated in the gas flowing in the gap between the end surface and the introduction wall, and leakage flow is suppressed.

Japanese Patent Laid-Open No. 11-229815 (page 4, FIG. 1)

 However, the variable wing disclosed in Patent Document 1 has both end faces that are wider than the cross section of the central portion, so that when the direction of the variable wing is changed, both ends of adjacent variable wings interfere with each other. There is a risk of doing. For this reason, the rotation range of the variable blades is limited, and the rotation range of the variable blades necessary for adjusting the gas flow rate in the variable capacity turbine may not be ensured.

 The present invention has been made in view of such circumstances, and even when a leakage flow occurs, a variable capacity type capable of suppressing a decrease in turbine efficiency due to the leakage flow and, as a result, improving the turbine efficiency. An object is to provide a turbine.

In order to solve the above problems, the present invention employs the following means.
The variable capacity turbine of the present invention includes a nozzle capable of increasing or decreasing the flow rate of the gas introduced into the rotor blade, and the nozzle is provided between a pair of introduction walls having a substantially annular shape and a pair of introduction walls so as to be rotatable. A variable displacement turbine having a plurality of variable blades, wherein the turbine projects from at least one introduction wall toward the other introduction wall, is located inside the variable blade with respect to the radial direction of the introduction wall, and By restricting the flow of the gas leaking from the gap between the one introduction wall, the flow direction of the gas leaking from the gap is changed to the flow direction of the gas passing through the openings between the adjacent variable blades. A configuration is employed in which a convex portion that is displaced along the direction is provided.

In the present invention employing such a configuration, the flow direction of the leakage flow is displaced in a direction along the flow direction of the gas passing through the opening. Therefore, in the present invention, it is possible to use the flow of leakage flow to rotate the rotor blade.
Further, in the present invention, when the leakage flow flows downstream through the end portion on the other introduction wall side of the convex portion, the leakage flow is separated from the one introduction wall. The separated leak flow is directly introduced into the rotor blade without joining with other leak flows around the rotor blade. Therefore, in the present invention, it is possible to suppress the gas flow turbulence that occurs when the leakage flow from the gap and another leakage flow merge, and loss due to this gas flow turbulence does not occur.

In the variable capacity turbine of the present invention, the convex portion is formed near the radially inner side of the downstream tip portion of the variable blade when the variable blade is at the position where the opening is the narrowest, and at least the convex portion The downstream tip portion adopts a configuration in which the variable blade extends substantially along the flow direction of the gas passing through the opening when the variable blade is at the position where the opening is narrowest.
In the present invention employing such a configuration, the leakage flow that flows in the vicinity of the radially inner side of the downstream tip of the variable wing is regulated by the downstream tip of the convex portion, and the flow direction of the gas passing through the opening It is displaced in the direction along

In the variable capacity turbine of the present invention, the upstream tip portion of the convex portion is located between the downstream tip portion of the variable blade and one introduction wall when the variable blade is at the position where the opening is narrowest. The structure of extending substantially along the flow direction of the gas leaking from the gap is adopted.
In the present invention employing such a configuration, the leakage flow that flows in the vicinity of the radially inner side of the downstream tip portion of the variable wing flows along the upstream tip portion of the convex portion without resistance.

In addition, the variable capacity turbine of the present invention employs a configuration in which the extending direction of the convex portion gradually changes from the upstream tip portion toward the downstream tip portion.
In the present invention employing such a configuration, the leakage flow that flows along the upstream tip portion of the convex portion flows along the downstream tip portion of the convex portion without resistance.

Further, the variable capacity turbine of the present invention employs a configuration in which the convex portion is formed in a substantially annular shape surrounding the rotor blade.
In the present invention employing such a configuration, the leakage flow leaking from the gap between the variable wing and the one introduction wall is regulated by the convex portion formed in a substantially annular shape, and the gas passing through the opening is Displaces in the direction along the flow direction.

The variable capacity turbine of the present invention employs a configuration in which the protruding height of the convex portion from one introduction wall is 5% or more and 10% or less with respect to the interval between the pair of introduction walls.
In the present invention employing such a configuration, since the protruding height of the convex portion is 5% or more with respect to the interval between the pair of introduction walls, the leakage flow follows the flow direction of the gas passing through the opening. Displace in the direction. Moreover, in this invention, since the protrusion height of a convex part is 10% or less with respect to the said space | interval, the flow of the gas which passes an opening part is not inhibited.

Further, the variable capacity turbine of the present invention employs a configuration in which the flow surface on which the gas of the convex portion flows gradually inclines toward the outer side in the radial direction as the distance from the one introduction wall increases.
In the present invention employing such a configuration, it is difficult for the leakage flow to flow downstream from the other introduction wall side end of the convex portion, and the direction along the flow direction of the gas passing through the opening It becomes easy to displace.

According to the present invention, the following effects can be obtained.
According to the present invention, even if a leakage flow leaking from the gap between the variable blade and the introduction wall occurs, the flow of the leakage flow can be used to rotate the rotor blade, and the leakage flow Since turbulence of gas flow due to the occurrence can be suppressed, there is an effect that the turbine efficiency can be improved as compared with the conventional variable capacity turbine.

1 is a schematic diagram showing an overall configuration of a variable capacity turbine A according to a first embodiment. It is an enlarged view of the nozzle 5 periphery in FIG. It is a front view of the nozzle 5 in 1st Embodiment. FIG. 4 is an enlarged view around the nozzle vane 53 in FIG. 3. It is the schematic which shows the flow direction of the leakage flow which leaks through the clearance gap S1 when the opening part S3 in 1st Embodiment is the minimum. It is an enlarged view of the nozzle vane 53 periphery in 2nd Embodiment. It is an enlarged view of the nozzle vane 53 periphery in 3rd Embodiment. It is the schematic which shows the modification of the convex part 55, the 2nd convex part 56, and the 3rd convex part 57 in 1st, 2nd and 3rd embodiment.

Embodiments of the present invention will be described below with reference to the drawings.
[First Embodiment]
The configuration of the variable capacity turbine A according to the first embodiment will be described with reference to FIGS. 1 to 4.
FIG. 1 is a schematic diagram showing an overall configuration of a variable capacity turbine A according to the first embodiment. FIG. 2 is an enlarged view around the nozzle 5 in FIG. FIG. 3 is a front view of the nozzle 5 according to the first embodiment. FIG. 4 is an enlarged view around the nozzle vane 53 in FIG. In addition, the arrow F in the said figure shows the front.

The variable capacity turbine A according to this embodiment is a variable capacity turbocharger (not shown) that supercharges air to the engine using the kinetic energy of exhaust gas (gas) guided from an engine (not shown). It is used.
As shown in FIG. 1, the variable displacement turbine A includes a turbine housing 1 and a bearing housing 2 that is integrally connected to the front side of the turbine housing 1.

 The turbine housing 1 includes an impeller (rotary blade) 3, a turbine scroll flow path 4, a nozzle 5, and a discharge port 6.

 The impeller 3 is provided at a substantially central portion of the turbine housing 1 so as to be rotatable around a predetermined axis extending in the front-rear direction. The impeller 3 has a configuration in which a plurality of blades 32 are arranged at substantially equal intervals in the circumferential direction on the outer circumferential surface of a base 31 having a substantially conical shape. The impeller shaft 33 extending in the front-rear direction is integrally connected. The impeller shaft 33 is rotatably provided on the bearing housing 2 via the bearing 21 and is integrally connected to a centrifugal compressor (not shown).

 The turbine scroll passage 4 is formed in a substantially annular shape so as to surround the impeller 3 in the circumferential direction thereof, and is a passage through which engine exhaust gas is introduced. The turbine scroll flow path 4 is connected to an exhaust gas inlet (not shown).

The nozzle 5 surrounds the impeller 3 in the circumferential direction thereof, is provided on the radially inner side of the turbine scroll flow path 4, and has a substantially annular shape. The nozzle 5 is a flow path for supplying the exhaust gas introduced from the turbine scroll flow path 4 to the impeller 3, and can increase or decrease the flow rate of the exhaust gas.
A plurality of nozzles 5 are rotatable between a first ring (introduction wall) 51 and a second ring (introduction wall) 52, which are plate-like members having a substantially annular shape, and between the first ring 51 and the second ring 52. And a nozzle vane (variable blade) 53 provided.

The first ring 51 and the second ring 52 are provided to face each other and are integrally connected via a plurality of connecting pins 54. The second ring 52 is provided on the front side of the first ring 51.
As shown in FIG. 2, the first facing surface 51a and the second facing surface 52b, which are the surfaces of the first ring 51 and the second ring 52 facing each other, are both formed in a planar shape. The first ring 51 and the second ring 52 are respectively formed with a first hole 51c and a second hole 52d penetrating in the front-rear direction.

The nozzle vane 53 is a plate-like member having a substantially rectangular shape, and a cross section in a direction orthogonal to the front-rear direction is formed in a so-called wing shape in which the central portion is thick and both end portions are thin (see FIG. 4). At both ends of the nozzle vane 53 in the front-rear direction, a first end surface 53a and a second end surface 53b are formed parallel to the first facing surface 51a and the second facing surface 52b, respectively.
A gap S1 for smoothly rotating the nozzle vane 53 is formed between the first facing surface 51a and the first end surface 53a. Similarly, a gap is formed between the second facing surface 52b and the second end surface 53b. S2 is formed.
A first shaft 53c and a second shaft 53d protrude in the front-rear direction from the first end surface 53a and the second end surface 53b, respectively, and the first shaft 53c and the second shaft 53d have a first hole 51c and a second hole, respectively. Each of the portions 52d is rotatably fitted.

 As shown in FIG. 3, a plurality of nozzle vanes 53 are provided between the first ring 51 and the second ring 52 at substantially equal intervals in the circumferential direction. Openings S3 are respectively formed between a plurality of adjacent nozzle vanes 53, and the size of the openings S3 can be changed by changing the direction of the nozzle vanes 53. The engine exhaust gas flows along the direction of the nozzle vane 53 from the radially outer side toward the inner side through the opening S3. 3 and 4, the position of the nozzle vane 53 when the opening S3 is the minimum is represented by a solid line, and the position of the nozzle vane 53 when the opening S3 is the maximum is represented by a two-dot chain line.

A plurality of convex portions 55 extending in a predetermined direction are provided on the first facing surface 51 a of the first ring 51.
The convex portion 55 projects from the first facing surface 51a toward the second ring 52, and is provided in the vicinity of the radially inner side of the downstream end portion 53e in the nozzle vane 53 when the opening S3 is minimized. Further, as shown in FIG. 4, the convex portion 55 extends substantially along the direction of the arrow V indicating the flow direction of the exhaust gas passing through the opening S3 when the opening S3 is minimum. .
As shown in FIG. 2, the protrusion height W of the convex portion 55 from the first facing surface 51a is formed to be 5% or more and 10% or less of the distance D between the first facing surface 51a and the second facing surface 52b. Has been. Further, the cross section of the convex portion 55 in the width direction has a rectangular shape.

As shown in FIG. 1, the discharge port 6 is a portion for discharging exhaust gas introduced into the turbine housing 1, and is provided on the rear side of the impeller 3. The discharge port 6 is connected to an unillustrated harmful component suppressing device (catalyst) and a silencer.
A drive unit 7 for rotating the plurality of nozzle vanes 53 in synchronization is provided on the front side of the nozzle 5.

 Subsequently, the operation and action of the variable displacement turbine A according to the present embodiment will be described.

First, the operation of the variable displacement turbine A will be described.
Exhaust gas discharged from the engine is introduced into the turbine scroll passage 4 through the suction port of the variable displacement turbine A. Since the turbine scroll passage 4 is formed in a substantially annular shape, the exhaust gas flows so as to rotate in the circumferential direction around the impeller 3. Next, the exhaust gas is introduced into the blade 32 of the impeller 3 through the opening S3 of the nozzle 5, and is introduced so as to swirl around the impeller 3 due to the rotational flow. The impeller 3 is rotated by the flow of the exhaust gas.

Since the impeller 3 is connected to a centrifugal compressor (not shown) via the impeller shaft 33, the centrifugal compressor compresses air and supplies the compressed air to the engine. This supply operation can improve the performance of the engine.
When exhaust gas is introduced into the impeller 3 through the nozzle 5, the flow rate of the exhaust gas introduced into the impeller 3 is increased or decreased by changing the direction of the nozzle vane 53 and changing the size of the opening S3. be able to. By increasing or decreasing the flow rate of the exhaust gas in this way, it is possible to improve the performance of the engine over a wide range from the low rotation range to the high rotation range.

The exhaust gas that has rotated the impeller 3 flows to the rear side of the impeller 3 and is discharged from the discharge port 6.
The operation of the variable displacement turbine A is thus completed.

Next, the operation and action of the convex portion 55 in the present embodiment for displacing the flow direction of the exhaust gas (leakage flow) leaking from the gap S1 will be described with reference to FIG.
FIG. 5 is a schematic diagram showing the flow direction of the leakage flow that leaks through the gap S1 when the opening S3 in the first embodiment is the minimum, which is analyzed using simulation.

As described above, the exhaust gas is introduced into the impeller 3 through the opening S3 of the nozzle 5. As shown in FIG. 4, for example, the exhaust gas passing through the opening S3 when the opening S3 is the minimum flows in the direction indicated by the arrow V.
Most of the exhaust gas is introduced into the impeller 3 through the opening S3, but gaps S1 and S2 are formed between the nozzle vane 53 and the first ring 51 and the second ring 52, respectively. Some exhaust gas leaks through the gaps S1 and S2. In the following description, the operation / action for displacing the flow direction of the leakage flow is described for the case where the opening S3 is minimized.

 As shown in FIG. 5, the leakage flow of the exhaust gas passing through the gap S <b> 1 flows substantially along the thickness direction of the nozzle vane 53. In the leakage flow leaking radially inward of the nozzle vane 53, the leakage flow leaking from the upstream tip portion 53f side of the nozzle vane 53 changes its flow direction to the downstream tip portion 53e side, and the downstream tip portion 53e of the nozzle vane 53 is placed. It merges with the leaked flow that leaked from. This is because the exhaust gas flowing in the adjacent opening S3 is energized. Therefore, the leakage flow leaking from the gap S1 when the opening S3 is the minimum is almost concentrated near the radially inner side of the downstream end portion 53e of the nozzle vane 53 and flows in the direction of the arrow v1 shown in FIG.

As shown in FIG. 4, a convex portion 55 is provided near the radially inner side of the downstream end portion 53e, and the protrusion height W of the convex portion 55 from the first facing surface 51a also regulates the leakage flow. Therefore, the leakage flow is restricted by the convex portion 55 because it is formed at an appropriate height (5% or more with respect to the distance D between the first opposing surface 51a and the second opposing surface 52b). The portion 55 can be displaced in a direction along the extending direction. Therefore, the leakage flow flows in the direction of the arrow v2 shown in FIG.
Since the extending direction of the convex portion 55 is formed substantially the same as the direction of the arrow V that is the flow direction of the exhaust gas passing through the opening S3, the direction of the arrow v2 that is the flow direction of the leakage flow is the arrow V Is almost the same. In order to efficiently rotate the impeller 3 when the opening S3 is the minimum, the exhaust gas needs to be introduced into the impeller 3 in the direction of the arrow V. Therefore, the leakage flow displaced in the direction of the arrow v2 Can be used to rotate the impeller 3.

As shown in FIG. 2, all of the leakage flow is not displaced in the direction of the arrow v2, but a part of the leakage flow passes through the end of the convex portion 55 on the second ring 52 side to the downstream side. To flow. This flow direction is indicated by an arrow v3 in FIG.
Since the convex part 55 has the protrusion height W from the 1st opposing surface 51a, the leak flow which flowed to the downstream side through the said edge part is the position spaced apart by the distance W from the 1st opposing surface 51a. Flow. The leaking flow flowing away from the impeller 3 is directly introduced into the blade 32 without joining with other leakage flows around the blade 32 of the impeller 3. Therefore, it is possible to suppress the flow disturbance of the exhaust gas that occurs when the leak flows merge and the loss due to this flow disturbance.
The operation for displacing the flow direction of the leakage flow leaking from the gap S1 is thus completed.

As shown in FIG. 4, when the size of the opening S3 changes, the flow direction of the exhaust gas flowing through the opening S3 also changes. On the other hand, since the extending direction of the convex portion 55 is constant, it is difficult to use the kinetic energy of the leakage flow to rotate the impeller 3 except when the opening S3 is minimum.
However, when the opening S3 is the smallest, the difference between the radially outer exhaust gas internal pressure and the inner exhaust gas internal pressure at the nozzle 5 is maximized, so that the flow rate of the leakage flow leaking from the gap S1 is maximized. . Therefore, the improvement effect on the turbine efficiency can be effectively obtained by displacing the leakage flow from the gap S1 when the opening S3 is the minimum.

 When the exhaust gas flows in a direction different from the arrow V, the flow direction and the extending direction of the convex portion 55 are different, but the protruding height of the convex portion 55 is the first facing surface 51a. 10% or less with respect to the distance D between the second opposing surface 52b and the second opposing surface 52b, the flow of the exhaust gas through the opening S3 is not hindered.

Therefore, according to the present embodiment, the following effects can be obtained.
According to this embodiment, even if a leakage flow leaking from the gap S1 between the nozzle vane 53 and the first ring 51 occurs, the flow of the leakage flow can be used to rotate the impeller 3, and Since the gas flow turbulence due to the leakage flow can be suppressed, the turbine efficiency can be improved as compared with the conventional variable capacity turbine.

[Second Embodiment]
The configuration of the variable capacity turbine A2 according to the second embodiment will be described with reference to FIG.
FIG. 6 is an enlarged view around the nozzle vane 53 in the second embodiment. In FIG. 6, the same components as those of the first embodiment shown in FIG. 4 are denoted by the same reference numerals, and the description thereof is omitted.

 The variable displacement turbine A2 according to this embodiment differs from the variable displacement turbine A according to the first embodiment in that the convex portion 55 in the first embodiment is changed to a second convex portion 56. It is. Therefore, in the following description, only the configuration, operation and action of the second convex portion 56 will be described. In addition, the nozzle vane 53 shall be located in the direction which makes the opening part S3 the minimum.

As shown in FIG. 6, the second convex portion 56 is provided near the radially inner side of the downstream end portion 53 e of the nozzle vane 53. The extending direction of the second convex portion 56 is different between the upstream tip portion 56a and the downstream tip portion 56b.
More specifically, the extending direction of the upstream tip 56a is formed substantially the same as the direction of the arrow v1 indicating the flow direction of the leakage flow. Further, the extending direction of the downstream end portion 56b is formed substantially the same as the direction of the arrow V indicating the flow direction of the exhaust gas passing through the opening S3. In addition, the extending direction of the 2nd convex part 56 is changing gradually as it goes to the downstream front-end | tip part 56b from the upstream front-end | tip part 56a.

 The protruding height W of the second convex portion 56 from the first facing surface 51a is formed to be 5% or more and 10% or less of the distance D between the first facing surface 51a and the second facing surface 52b. The cross section in the width direction of the second convex portion 56 has a rectangular shape.

 Subsequently, the operation and action of displacing the flow direction of the leaked flow leaking from the gap S1 using the second convex portion 56 in the present embodiment will be described.

 Similar to the first embodiment, the leakage flow leaking from the gap S1 is concentrated near the radially inner side of the downstream end portion 53e in the nozzle vane 53 and flows in the direction of the arrow v1 (see FIG. 5). This leakage flow is introduced at a location where the upstream tip 56a of the second convex portion 56 is provided, but the upstream tip 56a extends in a direction substantially along the arrow v1. The leakage flow can flow along the upstream end portion 56a without resistance.

 Next, the leakage flow flows along the radially outer surface of the second convex portion 56. Here, since the extending direction of the second convex portion 56 gradually changes from the upstream tip portion 56a toward the downstream tip portion 56b, the leakage flow can follow the downstream tip portion 56b without resistance. . Since the downstream end 56b is formed substantially in the same direction as the arrow V indicating the flow direction of the exhaust gas passing through the opening S3, the leakage flow is directed in the same direction as the arrow V, that is, in the direction of the arrow v2. Can be displaced.

 As in the first embodiment, the leakage flow flowing downstream from the end surface on the second ring 52 side of the second convex portion 56 without being displaced in the direction of the arrow v2 can be separated from the first facing surface 51a. It is.

Therefore, according to the present embodiment, the following effects can be obtained.
According to the present embodiment, the same effect as that of the first embodiment can be obtained, and the loss generated when the leakage flow is introduced into the second convex portion 56 and the leakage flow in the direction of the arrow v2. It is possible to reduce the loss that occurs when displacement occurs. Therefore, compared with the first embodiment, there is an effect that the turbine efficiency can be further improved.

[Third Embodiment]
A configuration of a variable displacement turbine A3 according to the third embodiment will be described with reference to FIG.
FIG. 7 is an enlarged view around the nozzle vane 53 in the third embodiment. In FIG. 7, the same components as those of the first embodiment shown in FIG. 4 are denoted by the same reference numerals, and the description thereof is omitted.

 The variable displacement turbine A3 according to the present embodiment is different from the variable displacement turbine A according to the first embodiment in that the convex portion 55 in the first embodiment is changed to a third convex portion 57. It is. Therefore, in the following description, only the configuration, operation and action of the third convex portion 57 will be described. In addition, the nozzle vane 53 shall be located in the direction which makes the opening part S3 the minimum.

 As shown in FIG. 7, the third convex portion 57 is provided on the radially inner side of the nozzle vane 53, and is formed in a substantially annular shape surrounding the impeller 3.

 The protruding height W of the third convex portion 57 from the first facing surface 51a is 5% to 10% of the distance D between the first facing surface 51a and the second facing surface 52b. Further, the cross section of the third convex portion 57 in the width direction has a rectangular shape.

 Next, the operation and action for displacing the flow direction of the leaked flow leaking from the gap S1 using the third convex portion 57 in the present embodiment will be described.

 Similar to the first embodiment, the leakage flow leaking from the gap S1 is concentrated near the radially inner side of the downstream end portion 53e in the nozzle vane 53 and flows in the direction of the arrow v1 (see FIG. 5). This leakage flow is introduced at a location where the third convex portion 57 is provided, but the arrow v1 is not orthogonal to the tangential direction of the third convex portion 57 and is inclined in the same direction as the arrow V. ing. Therefore, the leakage flow introduced into the third convex portion 57 in the direction of the arrow v1 can be displaced in the direction along the arrow V, that is, the direction of the arrow v2 by the third convex portion 57 regulating.

 As in the first embodiment, the leakage flow flowing downstream from the end surface on the second ring 52 side of the third protrusion 57 without being displaced in the direction of the arrow V can be separated from the first facing surface 51a. It is. But since the 3rd convex part 57 is formed in the substantially cyclic | annular form, even if a leak flow is introduced from what direction, all the leak flows can be spaced apart from the 1st opposing surface 51a.

Therefore, according to the present embodiment, the following effects can be obtained.
According to this embodiment, even if a leakage flow leaking from the gap S1 between the nozzle vane 53 and the first ring 51 occurs, the flow of the leakage flow can be used to rotate the impeller 3, and Since the gas flow turbulence due to the leakage flow can be suppressed, the turbine efficiency can be improved as compared with the conventional variable capacity turbine.

 Note that the operation procedures shown in the above-described embodiment, or the shapes and combinations of the components are examples, and can be variously changed based on process conditions, design requirements, and the like without departing from the gist of the present invention. is there.

For example, in the above embodiment, the convex portion 55, the second convex portion 56, and the third convex portion 57 protrude from the first facing surface 51a, but the present invention is not limited to such a configuration, You may protrude toward the 1st ring 51 from the 2nd opposing surface 52b. Since a leak flow is generated not only from the gap S1 but also from the gap S2, the turbine efficiency can be improved by displacing the leak flow. Moreover, you may provide the said convex part in any of the 1st opposing surface 51a and the 2nd opposing surface 52b.
In addition, compared with the case where the said convex part is provided only in the 2nd opposing surface 52b, when it provides only in the 1st opposing surface 51a, turbine efficiency can be improved more largely. Therefore, it is preferable to provide the convex portion on at least the first facing surface 51a.

Moreover, in the said embodiment, although the cross section of the width direction of the convex part 55, the 2nd convex part 56, and the 3rd convex part 57 showed all the rectangles, this invention is not limited to such a structure. For example, the shape shown in FIG. FIG. 8 is a schematic diagram illustrating a modification of the convex portion 55, the second convex portion 56, and the third convex portion 57 in the first, second, and third embodiments.
That is, as shown in FIG. 8, the flow surface 58 on which the leakage flow in the convex portion flows is inclined toward the radially outer side in a direction that is gradually orthogonal as the distance from the first facing surface 51a increases. There may be. By adopting such a configuration, it is possible to suppress the leakage flow from passing over the end 58a of the convex portion on the second ring 52 side and flowing downstream, and as a result, the leakage flow passes through the opening S3. There is an effect of being easily displaced in a direction along the flow direction of the exhaust gas.

A, A2, A3 ... variable displacement turbine, 3 ... impeller (rotary blade), 5 ... nozzle, 51 ... first ring (introduction wall), 52 ... second ring (introduction wall), 53 ... nozzle vane (variable blade) 53e ... downstream end, 55 ... convex, 56 ... second convex, 56a ... upstream tip, 56b ... downstream tip, 57 ... third convex, 58 ... fluid surface, S3 ... opening

Claims (7)

The nozzle includes a nozzle that can increase or decrease the flow rate of the gas introduced into the rotor blade, and the nozzle includes a pair of introduction walls that are substantially annular, and a plurality of variable blades that are rotatably provided between the pair of introduction walls. A variable capacity turbine,
Projecting from at least one of the introduction walls toward the other introduction wall, located inside the variable wing with respect to the radial direction of the introduction wall, and from a gap between the variable wing and the one introduction wall By restricting the flow of the leaking gas, the flow direction of the gas leaking from the gap is displaced in a direction along the flow direction of the gas passing through the openings between the plurality of adjacent variable blades. A variable capacity turbine having a convex portion. The convex portion is formed in the vicinity of the radially inner side of the downstream tip portion of the variable wing when the variable wing is at a position that narrows the opening.
At least the downstream tip of the convex portion extends substantially along the flow direction of the gas passing through the opening when the variable blade is at the position where the opening is narrowest. The variable capacity turbine according to claim 1, wherein the turbine is a variable capacity turbine.  The upstream tip portion of the convex portion leaks from the gap between the downstream tip portion of the variable blade and the one introduction wall when the variable blade is at the position where the opening is narrowest. The variable capacity turbine according to claim 2, wherein the variable capacity turbine extends substantially along a gas flow direction.  4. The variable capacity turbine according to claim 3, wherein an extending direction of the convex portion gradually changes from the upstream tip portion toward the downstream tip portion.  The variable capacity turbine according to claim 1, wherein the convex portion is formed in a substantially annular shape surrounding the rotor blade.  The protrusion height from the said one introduction wall of the said convex part is 5% or more and 10% or less with respect to the space | interval of a pair of said introduction wall, The Claim 1 characterized by the above-mentioned. The variable displacement turbine described. The flow surface through which the gas of the convex portion flows is gradually inclined toward the outer side in the radial direction as the gas flows away from the one introduction wall. The variable displacement turbine described.

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