JP6195308B2 - Axial-flow turbine labyrinth seal device and exhaust gas turbocharger equipped with the same - Google Patents

Description

  The present invention relates to a labyrinth seal device for an axial flow turbine and an exhaust gas turbine supercharger including the same.

As shown in Patent Documents 1 and 2 and FIG. 6 below, for example, a conventional axial-flow exhaust gas turbocharger 101 driven by exhaust gas from an internal combustion engine includes a turbine shaft 4 that is supported by a bearing stand 2. And a turbine rotor 8 in which a turbine disk 6 and an exhaust gas turbine blade 7 are provided integrally with each other.
Further, an exhaust gas passage 13 is formed in the exhaust gas outlet casing 12 provided around the bearing stand 2 along the axial direction of the turbine shaft 4, and the exhaust gas turbine blade is formed by the exhaust gas of the internal combustion engine flowing through the exhaust gas passage 13. By driving 7, the turbine rotor 8 and the turbine shaft 4 rotate to generate power.
Then, a compressor (intake turbine blade) (not shown) provided on the other end side of the turbine shaft 4 is rotationally driven, whereby the air taken in by the internal combustion engine is compressed and supercharged.

  A known air labyrinth seal AL (multistage labyrinth fin) is formed between the turbine disk 6 and an annular labyrinth member 22 that is fixed to the bearing stand 2 side and adjacent to the exhaust gas downstream side of the turbine disk 6. Part of the air compressed by the above-described compressor is extracted by the extraction passage 24 into the narrow labyrinth gap (usually about 1 to 2 mm) between the air labyrinth seals AL and supplied as seal air.

  The supply of the sealing air generates a thrust force that presses the turbine rotor 8 and the turbine shaft 4 to the exhaust gas upstream side against the pressure of the exhaust gas, thereby reducing the burden on a thrust bearing (not shown) and at the same time. The driving force required to rotate 4 is reduced. Further, the exhaust gas flowing through the exhaust gas passage 13 is prevented from entering the bearing base 2 from between the turbine disk 6 and the labyrinth member 22 (labyrinth gap). The seal air thus supplied to the air labyrinth seal AL is discharged from the labyrinth gap into the exhaust gas passage 13 substantially perpendicularly to the exhaust gas flow direction as indicated by an arrow.

Japanese Utility Model Publication No. 04-026661 JP 2009-287539 A

  In FIG. 6, the pressure of the exhaust gas flowing through the exhaust gas passage 13 is normally reduced to 0.05 bar or less on the downstream side of the exhaust gas turbine blade 7. On the other hand, the pressure of the seal air discharged from the labyrinth gap into the exhaust gas passage 13 is about 4 bar at the maximum, which is higher than the pressure of the exhaust gas passing through this position. For this reason, the seal air is jetted vertically from the labyrinth gap at a high flow rate to the downstream side of the exhaust gas turbine blade 7, which causes a disturbance in the flow of the exhaust gas immediately downstream of the exhaust gas turbine blade 7. That is, it has been found that the flow of exhaust gas is separated from the inner surface of the exhaust gas passage 13 due to the ejection of high-pressure sealing air, which causes a reduction in turbine efficiency.

  Further, the exhaust gas outlet casing 12 constituting the exhaust gas passage 13 is thermally expanded by receiving the heat of the exhaust gas, and its end 12a tends to be close to the turbine disk 6 side. For this reason, the gap G between the end 12a of the exhaust gas outlet casing 12 and the turbine disk 6 needs to be larger than the labyrinth gap in consideration of the above-described thermal elongation, and is generally about 5 to 6 mm. Set to Due to the presence of the gap G, the flow of the exhaust gas immediately after passing through the exhaust gas turbine blade 7 is disturbed, and there is a concern that the turbine efficiency may be lowered in this respect as well.

  The present invention has been made in view of the above circumstances, and the exhaust gas flow immediately after passing through the exhaust gas turbine blades is discharged into the exhaust gas passage from the shape of the exhaust gas passage or the gas (air) labyrinth seal. An object of the present invention is to provide a labyrinth seal device for an axial-flow turbine that can be prevented from being disturbed by (or seal air) and increase turbine efficiency, and an exhaust gas turbine supercharger including the same.

  In order to solve the above-mentioned problems, a labyrinth seal device for an axial-flow turbine according to a first aspect of the present invention includes a turbine shaft that is pivotally supported by a bearing stand, a turbine disk provided on the turbine shaft, and the turbine disk. An exhaust gas turbine blade provided on the outer periphery of the gas turbine, a casing for supplying exhaust gas to the exhaust gas turbine blade, and forming an exhaust gas passage for discharging the exhaust gas that has passed through the exhaust gas turbine blade to the outside of the system, and the bearing stand side And an annular labyrinth member that forms a gas labyrinth seal adjacent to the exhaust gas downstream side of the turbine disk and seal gas flowing through the gas labyrinth seal in the exhaust gas passage on the exhaust gas downstream side of the exhaust gas turbine blade. A labyrinth seal device for an axial-flow turbine comprising: Rugasu discharge passage, characterized in that formed between the exhaust gas passage forming portion of said casing and said labyrinth members.

  According to the labyrinth seal device for an axial flow turbine having the above-described configuration, the seal gas is not provided between the turbine disk and the labyrinth member as in the prior art, but the seal gas discharge passage is provided at a position downstream of the labyrinth member. To the exhaust gas passage.

  As described above, the seal gas discharge position (seal gas discharge passage) is located downstream of the adjacent portion of the turbine disk and the labyrinth member, and therefore, at least in a region of the exhaust gas flow immediately after passing through the exhaust gas turbine blade. Can suppress the occurrence of turbulence in the flow due to the release of the high-pressure seal gas, thereby improving the turbine efficiency.

  Moreover, a labyrinth member is disposed between the casing (exhaust gas passage) that receives heat from the exhaust gas and thermally expands and the turbine disk, and a gap-like seal gas discharge passage is formed between the labyrinth member and the casing. Therefore, the thermal expansion of the casing is absorbed by the seal gas discharge passage.

  For this reason, unlike the conventional configuration in which the casing and the turbine disk are adjacent to each other, it is not necessary to set a large gap between the end of the exhaust gas outlet casing and the turbine disk in consideration of the thermal expansion of the casing. Moreover, since the labyrinth member is connected to a bearing stand that is not easily subjected to thermal stress, the labyrinth member does not thermally expand and approach the turbine disk. Therefore, the gap between the labyrinth member and the turbine disk can be set to a minimum.

  As a result, the flow of the exhaust gas immediately after passing through the exhaust gas turbine blades does not pass over a large gap, and the turbulence in the exhaust gas flow does not occur, and the turbine efficiency can be improved in this respect as well.

  In the said structure, it is preferable that the outer peripheral surface of the said labyrinth member forms the said waste gas passage with the said casing.

  Thus, since the outer peripheral surface of the labyrinth member forms an exhaust gas passage together with the casing, the flow of the exhaust gas immediately after passing through the exhaust gas turbine blades does not pass over a large gap, thereby suppressing the disturbance of the exhaust gas flow. Turbine efficiency can be improved.

  In the above configuration, the joining portion of the seal gas discharge passage and the exhaust gas passage is formed so that the flow direction of the seal gas has an axial component facing the downstream side of the exhaust gas passage. Is preferred.

  In this way, by forming the seal gas discharge passage, the seal gas discharged from the seal gas discharge passage into the exhaust gas passage is merged at a shallow angle with respect to the flow of the exhaust gas, thereby passing through the exhaust gas turbine blade. Turbulence of the exhaust gas flow immediately after the operation can be reduced, and the turbine efficiency can be further improved.

  The said structure WHEREIN: It is more preferable that the said sealing gas discharge passage is equipped with the bending part from which the flow direction of the said sealing gas changes.

  As described above, by providing the bent portion in the seal gas discharge passage, the flow resistance (pressure loss) of the seal gas flowing inside the seal gas discharge passage increases, and the flow velocity thereof decreases. For this reason, the disturbance of the exhaust gas flow when the seal gas is released into the exhaust gas passage can be suppressed, and the turbine efficiency can be further improved.

  In the above configuration, at the position of the seal gas discharge passage, the exhaust gas downstream end portion of the labyrinth member is overlapped with the outer peripheral side of the exhaust gas upstream end portion of the exhaust gas passage forming portion of the casing, and this overlapped portion Protruding members may be interspersed in the circumferential direction.

  According to the above configuration, even if the exhaust gas upstream side end portion of the casing forming the exhaust gas passage thermally expands and causes a deformation that generates a step on the inner surface of the exhaust gas passage, for example, this deformation is caused by the protruding member. It is suppressed by the labyrinth member.

  For this reason, the casing is prevented from being thermally expanded and deformed, the flow of exhaust gas is prevented from being disturbed, the turbine efficiency is prevented from being lowered, and the opening area of the seal gas discharge passage is reduced. This can be prevented.

An exhaust gas turbine supercharger according to the second aspect of the present invention includes any one of the labyrinth seal devices for an axial flow turbine described above, and a compressor is coaxially provided on the turbine shaft, and the energy of the exhaust gas. Thus, the compressor is rotated to supercharge the intake gas of the internal combustion engine.

  According to this exhaust gas turbine supercharger, the seal gas is not released from between the turbine disk and the labyrinth member as in the prior art, but is discharged into the exhaust gas passage at a position downstream of the labyrinth member. For this reason, it is possible to suppress the occurrence of turbulence due to the discharge of the high-pressure seal gas in the exhaust gas flow immediately after passing through the exhaust gas turbine blades, thereby improving the turbine efficiency.

  In addition, the thermal expansion of the casing is absorbed by the labyrinth member disposed between the casing and the turbine disk and the seal gas discharge passage provided between the casing. For this reason, the gap between the labyrinth member and the turbine disk can be set to a minimum, and the disturbance of the exhaust gas flow immediately after passing through the exhaust gas turbine blades can be suppressed to improve the turbine efficiency.

  As described above, according to the labyrinth seal device for an axial turbine according to the present invention and the exhaust gas turbine supercharger provided with the same, the exhaust gas flow immediately after passing through the exhaust gas turbine blades has the shape of the exhaust gas passage and the gas labyrinth. It can be prevented from being disturbed by the seal gas discharged from the seal into the exhaust gas passage, and the turbine efficiency can be improved.

1 is a longitudinal sectional view in the vicinity of an exhaust gas turbine in an exhaust gas turbocharger to which a labyrinth seal device according to the present invention is applied. It is an enlarged view of the labyrinth seal device vicinity which shows 1st Embodiment of this invention. It is an enlarged view of the labyrinth seal device vicinity which shows 2nd Embodiment of this invention. It is an enlarged view of the labyrinth seal device vicinity which shows 3rd Embodiment of this invention. It is a longitudinal cross-sectional view which follows the VV line of FIG. It is a longitudinal cross-sectional view of the exhaust gas turbine vicinity in the exhaust gas turbine supercharger to which the conventional labyrinth seal device was applied.

A plurality of embodiments of the present invention will be described below with reference to FIGS.
[First Embodiment]
FIG. 1 is a longitudinal sectional view showing the vicinity of an exhaust gas turbine in an axial flow type exhaust gas turbine supercharger to which the labyrinth seal device according to the present invention is applied, and FIG. 2 is a labyrinth seal showing a first embodiment of the present invention. It is an enlarged view near the device.

  The exhaust gas turbine supercharger 1 is equipped with, for example, a large marine diesel engine (not shown) to supercharge intake gas. The exhaust gas turbine supercharger 1 is provided with a shaft 2 via a bearing base 2 and a pair of radial bearings 3. A supported turbine shaft 4, an exhaust gas turbine 5 (axial turbine) provided at one end of the turbine shaft 4 and driven at high speed by exhaust gas discharged from a large marine diesel engine, and coaxial with the other end of the turbine shaft 4 And a compressor (not shown) that compresses the intake gas and supercharges the large marine diesel engine by rotating the turbine shaft 4 by the energy of the exhaust gas.

  In addition, although air sucked from the outside of the large marine diesel engine is applied as the intake gas, other than this, for example, EGR gas using exhaust gas discharged from the large marine diesel engine may be applied.

  The exhaust gas turbine 5 includes a turbine rotor 8 including a disc-shaped turbine disk 6 provided integrally with one end of the turbine shaft 4 and a large number of exhaust gas turbine blades 7 provided at equal intervals on the outer periphery of the turbine disk 6. It has. The exhaust gas turbine 5 includes an exhaust gas inlet casing 11, an exhaust gas outlet casing 12 (casing), an exhaust gas passage 13, and a labyrinth seal device 15 described later.

  By combining the exhaust gas inlet casing 11 and the exhaust gas outlet casing 12, an exhaust gas passage 13 having a shape along the axial direction of the turbine shaft 4 and surrounding the turbine shaft 4 is formed. An exhaust gas turbine blade 7 projects into the exhaust gas passage 13 in the vicinity of the inlet of the exhaust gas outlet casing 12. Reference numeral 17 denotes a turbine nozzle installed on the inlet side of the exhaust gas turbine blade 7.

  The exhaust gas turbine blade 7 protruding inside the exhaust gas passage 13 is driven by the exhaust gas flow that flows through the exhaust gas passage 13 and is expanded in the turbine nozzle 17. As a result, the turbine rotor 8 and the turbine shaft 4 are rotated to generate power, and the above-described compressor (intake turbine) is driven by this power, and the gas sucked from the outside is compressed to be sucked into a large marine diesel engine. It is supplied (supercharged) as gas. The pressure of the exhaust gas after passing through the exhaust gas turbine blade 7 decreases to 0.05 bar or less.

  The labyrinth seal device 15 includes two annular labyrinth members 21 and 22. One labyrinth member 21 is fixed to the bearing stand 2 so as to be positioned between the radial bearing 3 and the turbine disk 6 in the axial direction of the turbine shaft 4 to constitute an oil labyrinth seal OL. The other labyrinth member 22 is fixed to the bearing stand 2 side so as to be adjacent to the exhaust gas downstream side (bearing stand 2 side) with respect to the turbine disk 6 to constitute a gas labyrinth seal GL. Each of these labyrinth seals OL and GL has a known configuration in which multi-stage labyrinth fins are engaged.

  An extraction passage 24 is formed inside the bearing stand 2. The extraction passage 24 is a gas passage that extracts a part of the suction gas compressed by the above-described compressor and supplies it to the oil labyrinth seal OL and the gas labyrinth seal GL. In addition, when EGR gas using exhaust gas discharged from a large marine diesel engine is applied as intake gas, EGR gas may be supplied as a seal gas to the oil labyrinth seal OL and the gas labyrinth seal GL.

As shown in FIG. 2, the labyrinth member 22 constituting the gas labyrinth seal GL has an exhaust gas passage so that the outer peripheral surface 22a does not generate a step with respect to the inner peripheral surface 13a of the exhaust gas passage 13 (exhaust gas outlet casing 12). The exhaust gas passage 13 is formed together with the exhaust gas outlet casing 12. Further, the labyrinth member 22 is fixed to the bearing block 2 so as to be adjacent through between gap-shaped seal gas discharge passage 26 between the exhaust gas outlet casing 12.

  A step portion 22b (see FIG. 2) whose outer diameter is smaller than the outer peripheral surface 22a is formed on the side of the labyrinth member 22 opposite to the turbine disk 6 and an annular gas seal ring 28 is fitted into the step portion 22b. . The outer peripheral surface of the gas seal ring 28 is slidably covered in the axial direction with the inner peripheral surface of the exhaust gas upstream end 12a of the exhaust gas outlet casing 12, and the exhaust gas upstream end 12a and the labyrinth member 22 A seal gas discharge passage 26 is formed therebetween.

  The end portion of the seal gas discharge passage 26, that is, the joining portion communicating with the exhaust gas passage 13, as indicated by an arrow in FIG. 1, the flow direction of the seal gas discharged from the seal gas discharge passage 26 into the exhaust gas passage 13. Is formed so as to have an axial component along the flow direction of the exhaust gas flowing through the exhaust gas passage 13 and toward the downstream side of the exhaust gas passage 13. That is, the end portion of the seal gas discharge passage 26 has a cross-sectional shape that merges obliquely with respect to the exhaust gas passage 13.

  As shown in FIG. 2, an air collection chamber 30 having a large clearance from the turbine disk 6 is formed in a portion of the labyrinth member 22 on the outer peripheral side of the gas labyrinth seal GL. The gap G1 between the portion on the outer peripheral side further than 30 and the turbine disk 6 is set to a minimum dimension, for example, about 1 mm. A deaeration passage 31 communicating with the seal gas discharge passage 26 from the air collection chamber 30 is also formed. A plurality of the deaeration passages 31 are provided in the circumferential direction of the labyrinth member 22.

  In the labyrinth seal device 15 configured as described above, a part of the suction gas compressed by the compressor is supplied to each of the oil labyrinth seal OL and the gas labyrinth seal GL as a seal gas through the extraction passage 24. . Specifically, the seal gas is first supplied from the extraction passage 24 to the oil labyrinth seal OL, and the seal gas discharged from the oil labyrinth seal OL is then supplied to the gas labyrinth seal GL. Thereafter, the gas is discharged into the exhaust gas passage 13 as indicated by an arrow in FIG. 1 from the gap-like seal gas discharge passage 26 located downstream of the exhaust gas turbine blade 7.

  Thereby, in the oil labyrinth seal OL, the lubricating oil supplied to the radial bearing 3 is prevented from leaking to the turbine disk 6 side due to the pressure of the seal gas. Further, in the gas labyrinth seal GL, the turbine disk 6 is pressed against the labyrinth member 22 toward the exhaust gas upstream side (rightward in FIG. 1) by the pressure of the seal gas. A thrust force that presses the turbine rotor 8 and the turbine shaft 4 to the upstream side of the exhaust gas is generated, and a burden on a thrust bearing (not shown) is reduced. At the same time, a driving force necessary to rotate the turbine shaft 4 is reduced. .

The seal gas after passing through the gas labyrinth seal GL flows into the air collecting chamber 30 (see FIG. 2), further flows through the deaeration passage 31 to the seal gas discharge passage 26, and is discharged into the exhaust gas passage 13. Thus, the position where the seal gas is discharged into the exhaust gas passage 13 is a position downstream of the adjacent portion (gap G1) between the turbine disk 6 and the labyrinth member 22 in the axial direction of the turbine shaft 4.

  Thus, the position (seal gas discharge passage 26) where the seal gas having a pressure higher than the exhaust gas is discharged into the exhaust gas passage 13 is the position of the conventional gap G shown in FIG. 6 (the gap between the turbine disk 6 and the labyrinth member 22). Since it is on the downstream side of the adjacent portion (gap G)), a high-pressure seal gas is applied to the exhaust gas flow in the vicinity of the position immediately after passing through the exhaust gas turbine blade 7 (position of the gap G1 that was the conventional seal gas outlet). It is possible to suppress the occurrence of turbulence due to the release of gas, thereby improving the turbine efficiency.

  In addition, a labyrinth member 22 is disposed between the exhaust gas outlet casing 12 that receives heat from the exhaust gas and thermally expands, and the turbine disk 6, and a gap-like seal gas is released between the labyrinth member 22 and the exhaust gas outlet casing 12. Since the passage 26 is formed, the thermal expansion of the exhaust gas outlet casing 12 is absorbed by the seal gas discharge passage 26.

  That is, when the exhaust gas outlet casing 12 is thermally expanded in the axial direction, the inner peripheral surface of the end portion 12a slides in the axial direction with respect to the outer peripheral surface of the gas seal ring 28, and the end portion 12a extends to the labyrinth member 22 side. Thus, since the axial length of the seal gas discharge passage 26 has a sufficient interval compared to the amount in which the exhaust gas outlet casing 12 extends in the axial direction due to thermal expansion, the thermally expanded exhaust gas outlet casing 12 interferes with the labyrinth member 22. Never do.

  As described above, since the thermal expansion of the exhaust gas outlet casing 12 is absorbed at the position of the seal gas discharge passage 26, as in the conventional configuration in which the exhaust gas outlet casing 12 and the turbine disk 6 are adjacent to each other (see FIG. 6). In consideration of the thermal expansion of the exhaust gas outlet casing 12, there is no need to set a large gap G1 between the end 12a of the exhaust gas outlet casing 12 and the turbine disk 6.

  Moreover, since the labyrinth member 22 is connected to the bearing stand 2 that is not easily subjected to thermal stress, the labyrinth member 22 does not thermally expand and approach the turbine disk 6. Thus, the gap G1 can be set to a minimum. Therefore, the step width in the exhaust gas passage 13 immediately downstream of the exhaust gas turbine blade 7 is reduced, and the disturbance of the exhaust gas flow due to separation of the boundary layer of the exhaust gas flow immediately after passing through the exhaust gas turbine blade 7 is reduced. In this respect as well, the turbine efficiency can be improved.

  Furthermore, since the end portion of the seal gas discharge passage 26 has a cross-sectional shape that merges obliquely with respect to the flow direction of the exhaust gas, the seal gas discharged from the seal gas discharge passage 26 into the exhaust gas passage 13 is transferred to the exhaust gas flow. Therefore, the turbulence of the exhaust gas flow immediately after passing through the exhaust gas turbine blades 7 (separation of the boundary layer, etc.) can be reduced, and the turbine efficiency can be further improved.

[Second Embodiment]
FIG. 3 is an enlarged view of the vicinity of the labyrinth seal device showing the second embodiment of the present invention. The labyrinth seal device 35 is different from the labyrinth seal device 15 of the first embodiment in that a bent portion is provided in the middle portion of the seal gas discharge passage 26, and other configurations are the same. Only the point will be described.

  The seal gas discharge passage 26 has two upstream end portions (portions where the deaeration passage 31 communicates) and a distal end portion that communicates obliquely with the exhaust gas passage 13. Bending portions 26a and 26b are provided. By providing these two bent portions 26a and 26b, the cross-sectional shape of the seal gas discharge passage 26 is bent in a crank shape.

  For this reason, the flow resistance (pressure loss) of the seal gas flowing inside the seal gas discharge passage 26 increases, and the flow velocity thereof decreases. Thereby, the disturbance of the exhaust gas flow when the seal gas is discharged into the exhaust gas passage 13 is reduced, and the turbine efficiency can be further improved. Various conditions such as the angle and quantity of the bent portions 26a and 26b can be changed as appropriate.

[Third Embodiment]
FIG. 4 is an enlarged view of the vicinity of the labyrinth seal device showing the third embodiment of the present invention. The labyrinth seal device 40 has the same cross-sectional shape as the labyrinth seal device 35 of the second embodiment. That is, two bent portions 26a and 26b are provided in the middle portion of the seal gas discharge passage 26, and the exhaust gas downstream end of the labyrinth member 22 is the end 12a (exhaust gas upstream end) of the exhaust gas outlet casing 12. It overlaps the outer periphery.

  As shown in FIG. 5, protrusion-like deformation suppressing members 43 are dotted in the circumferential direction on the outer peripheral surface of the exhaust gas outlet casing 12 in the overlapping portion. The deformation suppressing member 43 is formed in, for example, a rectangular column shape that is long in the axial direction, and is provided integrally or as a separate part on the outer peripheral surface of the exhaust gas outlet casing 12. Although the deformation suppressing member 43 may be formed on the labyrinth member 22 side, it is preferable that the deformation suppressing member 43 is provided on the outer peripheral surface of the exhaust gas outlet casing 12 in consideration of manufacturability. Note that the shape of the deformation suppressing member 43 may be a columnar shape, an airfoil cross-sectional shape, or the like.

  By providing such a deformation suppressing member 43, the end portion 12a on the exhaust gas upstream side of the exhaust gas outlet casing 12 is thermally expanded, and for example, a deformation that causes a step on the inner surface of the exhaust gas passage 13 is caused. This deformation is suppressed by the annular labyrinth member 22 via the protrusion-shaped deformation suppressing member 43.

  For this reason, it is possible to prevent the exhaust gas flow immediately after passing through the exhaust gas turbine blades 7 from being disturbed by the occurrence of a step on the inner surface of the exhaust gas passage 13 and to prevent the turbine efficiency from being lowered. Moreover, it is possible to prevent the opening area of the seal gas discharge passage 26 from being reduced due to the thermal expansion of the exhaust gas outlet casing 12.

  As described above, according to the labyrinth seal devices 15, 35, and 40 according to the present embodiment, the exhaust gas flow immediately after passing through the exhaust gas turbine blades 7 changes from the shape of the exhaust gas passage 13 and the gas labyrinth seal GL to the exhaust gas passage. It is possible to prevent the turbine 13 from being disturbed by the high-pressure seal gas discharged into the turbine 13 and increase the turbine efficiency.

  Further, according to the exhaust gas turbine supercharger 1 provided with such labyrinth seal devices 15, 35, and 40, the seal gas is not generated between the turbine disk 6 and the labyrinth member 22 (gap G 1) as in the prior art. Since it is discharged into the exhaust gas passage 13 at a position downstream of the labyrinth member 22, the exhaust gas flow immediately after passing through the exhaust gas turbine blades 7 is prevented from being disturbed by the release of the seal gas. Turbine efficiency can be improved.

  Moreover, thermal expansion of the exhaust gas outlet casing 12 is absorbed by a labyrinth member 22 disposed between the exhaust gas outlet casing 12 and the turbine disk 6 and a seal gas discharge passage 26 provided between the exhaust gas outlet casing 12. . For this reason, the gap G1 between the labyrinth member 22 and the turbine disk 6 can be set to a minimum, the disturbance of the exhaust gas flow immediately after passing through the exhaust gas turbine blades 7 can be eliminated, and the turbine efficiency can be improved.

  In addition, this invention is not limited to the said embodiment, In the range which does not deviate from the summary, it can add a change suitably. For example, in the above-described embodiment, the example in which the labyrinth seal device according to the present invention is applied to an exhaust gas turbocharger installed in a large marine diesel engine has been described. It can be widely applied to other types and applications of axial flow turbines such as jet engines.

DESCRIPTION OF SYMBOLS 1 Exhaust gas turbocharger 2 Bearing stand 4 Turbine shaft 5 Exhaust gas turbine (axial turbine)
6 Turbine disk 7 Exhaust gas turbine blade 8 Turbine rotor 12 Exhaust gas outlet casing (casing)
13 Exhaust gas passage 13a Inner peripheral surface 15, 35, 40 of exhaust gas passage Labyrinth seal device 22 Labyrinth member 22a Outer surface 26 of labyrinth member Seal gas discharge passages 26a, 26b Bending portion 43 Deformation suppressing member GL Gas labyrinth seal

Claims (6)

A turbine shaft supported by a bearing stand;
A turbine disk provided on the turbine shaft;
An exhaust gas turbine blade provided on the outer periphery of the turbine disk;
A casing that forms exhaust gas passages for supplying exhaust gas to the exhaust gas turbine blades and exhausting the exhaust gas that has passed through the exhaust gas turbine blades out of the system;
An annular labyrinth member fixed on the bearing stand side and constituting a gas labyrinth seal adjacent to the exhaust gas downstream side of the turbine disk;
A labyrinth seal device for an axial flow turbine, comprising: a seal gas discharge passage for discharging a seal gas flowing through the gas labyrinth seal into the exhaust gas passage on the exhaust gas downstream side of the exhaust gas turbine blade;
The labyrinth seal device for an axial-flow turbine, wherein the seal gas discharge passage is formed between the exhaust gas passage formation portion of the casing and the labyrinth member.   The labyrinth seal device for an axial flow turbine according to claim 1, wherein an outer peripheral surface of the labyrinth member forms the exhaust gas passage together with the casing.   The joining portion of the seal gas discharge passage with the exhaust gas passage is formed so that a flow direction of the seal gas has an axial component facing a downstream side of the exhaust gas passage. Labyrinth seal device of the axial flow turbine.   The labyrinth seal device for an axial flow turbine according to any one of claims 1 to 3, wherein the seal gas discharge passage includes a bent portion that changes a flow direction of the seal gas.   At the position of the seal gas discharge passage, the exhaust gas downstream side end portion of the labyrinth member overlaps with the outer peripheral side of the exhaust gas upstream side end portion of the exhaust gas passage forming portion of the casing, and the protruding member is disposed in the circumferential direction on the overlapped portion. The labyrinth seal device for an axial flow turbine according to claim 4, wherein the labyrinth seal device is interspersed with the axial flow turbine. An internal combustion engine comprising the labyrinth seal device for an axial turbine according to any one of claims 1 to 5, wherein a compressor is coaxially provided on the turbine shaft, and the compressor is rotationally driven by the energy of the exhaust gas. An exhaust gas turbocharger characterized by supercharging the intake gas .

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