JP2009250151A - Thrust reduction device of axial flow turbine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thrust reduction device of an axial flow turbine which can cope with a considerable increase in the capacity of an exhaust turbine supercharger and also cope with a higher pressure rate of a compressor by reducing a large thrust load directed from the upstream side of the turbine to the downstream side. <P>SOLUTION: The thrust reduction device of the axial flow turbine is provided with a turbine blade and the compressor. The turbine blade is driven by the exhaust gas flow in the axial direction which has been expanded by a turbine nozzle under static pressure, and the compressor is directly connected to the turbine blade through the medium of a turbine rotor shaft. A space in which leaked gas accumulates is formed on the side of the turbine rotor shaft placed on the inner surface of the turbine nozzle. A pressure reduction means is provided which reduces the pressure of the space, and the pressure of the space can be maintained at a lower level than that of the space on the side of a blade wheel by the pressure reduction means. The space on the side of the blade wheel is connected to the inlet port of the turbine blade by a minute passage. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention is applied to a large axial-flow turbine supercharger, and includes a turbine blade driven by an axial exhaust gas flow statically expanded by a turbine nozzle, and a compressor directly connected to the turbine blade. The present invention relates to a thrust load reducing device for axial turbine blades in which a space in which leakage gas or the like is accumulated is formed on a turbine rotor shaft side surface of an inner periphery of a nozzle.

FIG. 6 is a cross-sectional view taken along the rotational axis showing an example of the axial flow type exhaust turbine supercharger.
In FIG. 6, 10 is a turbine casing, 10b is an exhaust gas inlet passage, 10a is an outlet passage, 12 is an axial flow type turbine blade, 3 is a turbine nozzle installed at the inlet of the turbine blade 12, and the turbine nozzle The turbine blades 12 are rotationally driven by the axial exhaust gas flow statically expanded at 3.
A compressor 8 is directly connected to the turbine blade 12 via the turbine rotor shaft 2 and rotates together with the turbine blade 12.

The compressor 8 is accommodated in a compressor housing 7, and air is supplied to the compressor 8 from an air inlet 9 in the compressor housing 7. The air pressurized by the compressor 8 is supplied from the compressor 8 to the engine (not shown) through the diffuser 4 and the outlet scroll 7a.
The turbine rotor shaft 2 includes a disk 12 s and is supported by two radial bearings 16 and 16. Reference numeral 1a denotes a thrust bearing that receives thrust in the turbine axial direction. 100 is the rotation center of the supercharger.

During the operation of the axial flow type exhaust turbine supercharger having such a configuration, the exhaust gas from the engine (not shown) passes through the exhaust gas inlet passage 10b and is axially exhausted after being statically expanded by the turbine nozzle 3. The turbine blades 12 are rotationally driven by the flow. The exhaust gas that has driven the turbine blades 12 is discharged to the outside from the outlet passage 10a.
The rotation of the turbine blade 12 causes the compressor 8 to rotate through the turbine rotor shaft 2, and the intake air is pressurized by the compressor 8 through the air inlet passage 9 of the compressor housing 7. 4 through the outlet scroll 7a and supplied to the engine (not shown).

In the axial flow type exhaust turbine supercharger, as shown in FIG. 7, during the operation of the exhaust turbine supercharger, the pressure acting on the surface of the turbine blade 12, the disk 12 s, and the side surface 2 a of the turbine rotor shaft 2 is Since the pressure in the space 26 on the upstream side of the turbine is high, the thrust load F of the turbine is higher in the space 26 on the upstream side of the turbine. Further, the compressor 8 side is also higher on the upstream side of the turbine, and therefore the thrust load F of the turbine as a whole is from the inside of the space 26 on the upstream side of the turbine to the downstream side (from right to left in FIG. 7).
That is, in such an axial exhaust turbocharger, a large thrust load F is applied from the inside of the space 26 on the upstream side of the turbine to the downstream side (from right to left in FIG. 7) during operation of the exhaust turbine supercharger. receive.

Examples of the invention relating to the structure of the axial flow type exhaust turbine supercharger include Patent Document 1 (Japanese Patent Laid-Open No. 2002-70569) and Patent Document 2 (Japanese Patent Laid-Open No. 2001-317365).
JP 2002-70569 A JP 2001-317365 A

As described above, in such an axial exhaust turbocharger, a large thrust is generated from the inside of the space 26 on the upstream side of the turbine to the downstream side (right side to left side in FIG. 7) during the operation of the exhaust turbine supercharger. Receives load F.
In order to receive the thrust load F while rotating, that is, the thrust load F while allowing rotation of the turbine rotor shaft 2, the thrust bearing 1a (see FIG. 6) is provided on the stationary side.
However, although the thrust load F tends to increase due to the recent increase in capacity of the exhaust turbine supercharger and the increase in the pressure ratio of the compressor 8 (see FIG. 6), it is necessary to improve the load capacity of the thrust bearing 1a. There is a limit.

  Thus, during operation of the exhaust turbine supercharger, the thrust applied to the thrust bearing 1a is controlled by some method by controlling the large thrust load F directed from the inside of the space 26 on the upstream side of the rotating turbine to the downstream side. It is necessary to obtain a balance of thrust loads that can reduce the load F.

  In view of the problems of the prior art, the present invention reduces the large thrust load from the upstream side of the turbine to the downstream side, thereby reducing the large capacity of the exhaust turbine supercharger and increasing the pressure ratio of the compressor. An object of the present invention is to provide a thrust reduction device.

  The present invention achieves such an object, and comprises a turbine blade driven by an axial exhaust gas flow statically expanded by a turbine nozzle, and a compressor directly connected to the turbine blade via a turbine rotor shaft. A thrust reduction device for an axial flow turbine in which a space in which leakage gas accumulates is formed on the turbine rotor shaft side surface of the inner periphery of the turbine nozzle, the pressure reduction means for reducing the pressure of the space is provided, and the pressure reduction means The pressure of the space is configured to be kept lower than the pressure of the side surface of the impeller communicated with the inlet of the turbine blade through a micro passage (Claim 1).

In this invention, the pressure lowering means is specifically configured as follows.
(1) The pressure reducing means includes a labyrinth seal device that seals the inside of the space, a turbine rotor shaft that faces the space, and a through hole that communicates the space and the impeller side surface space. Is guided to the side surface space of the impeller through the through hole (Claim 2).

  (2) The pressure lowering means is provided with a case member that forms a plurality of blades facing the space at a shaft end portion of the turbine rotor shaft, and that provides a fluid seal to the blades on an outer peripheral portion of the blades, By rotating the blades, the gas in the space is sucked and guided to the side surface space of the impeller (Claim 3).

  (3) The pressure reducing means includes a screw having a fixed length formed on an outer periphery of a shaft end of the turbine rotor shaft, and a seal member that supports the screw with a fluid seal is provided on the outer periphery of the screw. By rotating the rotor shaft, the screw portion advances to guide the gas in the space to the impeller side space (claim 4).

The present invention can also be configured as follows.
(1) A turbine blade driven by an axial exhaust gas flow statically expanded by a turbine nozzle, and a compressor directly connected to the turbine blade via a turbine rotor shaft, and having an inner periphery of the turbine nozzle In an axial flow turbine thrust reduction device in which a space for collecting leaked gas is formed on a side surface of a turbine rotor shaft, the turbine impeller includes a lower portion of the space and an impeller outlet portion that communicates with a turbine passage at a minute passage. A communicating through hole is provided, and the gas space in the space is led to the impeller outlet through the through hole (Claim 5).

  (2) In the axial flow turbine thrust reduction device configured as described above, a check valve and an extraction pipe provided in series with an orifice communicating with the space and the atmosphere are provided, and the gas in the space is extracted. Through the atmosphere (Claim 6).

  According to the present invention, a space in which leakage gas accumulates is formed on the turbine rotor shaft side surface on the inner periphery of the turbine nozzle, and pressure reducing means for reducing the pressure in the space is provided, and the pressure reducing means provides the pressure in the space. Is kept lower than the pressure in the side surface space of the impeller communicated with the inlet of the turbine blade through a minute passage (Claim 1), and the turbine rotor shaft side surface on the inner periphery of the turbine nozzle is formed by the pressure reducing means. By connecting the space where leakage gas is accumulated and the pressure rises to the side surface space of the impeller communicated with the turbine blade inlet through the micro passage, the side surface space of the impeller is communicated with the inlet of the turbine blade through the micro passage. Since the pressure is kept low by the air suction pressure, the gas staying in the space is discharged to the side surface space of the impeller by the pressure reducing means, and as a result, the pressure in the space is Pressure differential decreases to a pressure level of wheel side space is eliminated.

  Therefore, the thrust load due to the pressure difference is reduced, and by reducing the thrust load, the axial flow type exhaust turbine supercharger that can cope with an increase in the capacity of the exhaust turbine supercharger and a higher pressure ratio of the compressor. Can provide a machine.

The pressure reducing means includes a labyrinth seal device that seals the inside of the space, a turbine rotor shaft facing the space, and a through hole that communicates the space with the impeller side space, If it is configured to lead to the impeller side space through the through hole (Claim 2),
By providing a through-hole that communicates the space with the impeller side surface space in the turbine rotor shaft facing the space, the gas in the radial through-hole is generated when the turbine rotor shaft rotates due to the pumping performance of the through-hole. Move in the radial direction.
As a result, the gas in the space sealed by the labyrinth seal device is sucked out, and the static pressure in the space is reduced.
As the static pressure is reduced, there is gas that passes through the labyrinth seal device and enters the space. However, the amount of gas discharged to the side surface of the impeller determined by the pumping performance and the labyrinth seal performance increases, and therefore The static pressure in the space is reduced, thereby reducing the thrust load.

Further, the pressure reducing means is provided with a case member that forms a plurality of blades facing the space at the shaft end portion of the turbine rotor shaft, and that provides a fluid seal to the blades on an outer peripheral portion of the blades. If the gas in the space is sucked by rotation and guided to the side surface space of the impeller (Claim 3),
The gas in the space moves in the radial direction along the blades by the pumping action by the rotation of the plurality of blades provided at the shaft end of the turbine rotor shaft, and as a result, the gas in the space partitioned by the case member. Are sucked out, and the static pressure in the space decreases.
There is gas that enters the space through the minute gap on the inner circumference of the case member as the static pressure decreases, but the amount of gas discharged into the side surface of the impeller by the blades of gas determined by the pumping performance and tip sealing performance Therefore, the static pressure in the space is reduced, thereby reducing the thrust load.

The pressure lowering means includes a screw having a fixed length on the outer periphery of the shaft end of the turbine rotor shaft, and a seal member that is supported on the screw by a fluid seal is provided on the outer periphery of the screw. When the screw part advances by the rotation of the gas, the gas in the space is guided to the side surface space of the impeller (Claim 4).
Due to the pumping action by the rotation of the screw provided on the outer periphery of the shaft end of the turbine rotor shaft, the gas in the screw portion moves in the axial direction, and as a result, the gas in the space partitioned by the seal member is sucked out, The static pressure in the space decreases.
Since the static pressure has decreased, there is gas that enters the space through a minute gap between the screw part and the seal member, but the amount of gas discharged into the side surface of the impeller side determined by the pumping performance and the seal performance of the screw part And thus the static pressure in the space is reduced, thereby reducing the thrust load.

Further, it is a thrust reduction means for an axial flow turbine in which a space in which leakage gas accumulates is formed on the turbine rotor shaft side surface on the inner periphery of the turbine nozzle, and communicates with the turbine impeller through a small passage from the space lower portion to the turbine blade outlet. If a through hole communicating with the impeller exit portion to be provided is provided, and the gas space in the space is guided to the impeller exit portion through the through hole (Claim 5),
An impeller outlet portion through which a small amount of gas communicates from the space side to the turbine blade outlet through a minute passage through a through hole communicating with the space and an impeller outlet portion communicated with the turbine blade outlet through a minute passage. Is discharged.
Along with this, a small amount of gas that has passed through the turbine nozzle is guided to the space upstream of the disk from the gap between the inner ring of the turbine nozzle and the outer edge of the disk.

The gas that has passed through the turbine nozzle has a strong circumferential velocity component. According to the angular momentum conservation measurement, the gas flowing into the space upstream of the disk from the gap between the inner ring of the turbine nozzle and the disk outer edge increases the velocity component in the circumferential direction more and more as it moves toward the inner periphery.
As a result, the pressure on the upstream side of the disk, that is, the pressure in the lower part of the space is greatly reduced on the inner peripheral side, compared with the case where a small amount of gas leakage does not occur as described above, thereby reducing the thrust load.

The gas leakage flow according to the present invention occurs in an operating state where the thrust load is large, that is, an operating state where the turbocharger speed is high and the turbine inlet pressure is high. On the other hand, under the condition where the turbocharger rotational speed is low and the turbine inlet pressure is low, the difference between the turbine blade inlet pressure and the turbine blade outlet pressure is almost eliminated, so that this leakage flow does not occur.
Therefore, this example is effective only in an operating state with a large thrust load.

Further, in the axial flow turbine thrust reducing apparatus configured as described above, an extraction pipe that communicates the space with the atmosphere and includes a check valve and an orifice in series is provided, and the gas in the space passes through the extraction pipe. If it is configured to discharge into the atmosphere (Claim 6),
A small amount of gas is exhausted from the space to the atmosphere through the extraction tube. Along with this, a small amount of gas that has passed through the turbine nozzle is guided to the space upstream of the disk from the gap between the inner ring of the turbine nozzle and the outer edge of the disk.
Here, the gas that has passed through the turbine nozzle has a strong circumferential velocity component. According to the angular momentum conservation measurement, the gas flowing into the space upstream of the disk from the gap between the inner ring of the turbine nozzle and the disk outer edge increases the velocity component in the circumferential direction more and more as it moves toward the inner periphery.
As a result, the pressure on the upstream side of the disk, that is, the pressure in the lower portion of the space is greatly reduced on the inner peripheral side, compared with the case where a small amount of gas leakage does not occur as described above, thereby reducing the thrust load.

The gas leakage flow according to the present invention occurs in an operating state with a large thrust load, that is, an operating state with a high turbocharger speed and a high turbine inlet pressure. On the other hand, under the condition where the turbocharger rotational speed is low and the turbine inlet pressure is low, the difference between the turbine blade inlet pressure and the turbine blade outlet pressure is almost eliminated, so that this leakage flow does not occur.
Therefore, this example is effective only in an operating state with a large thrust load.

  Also, if the check valve and orifice are placed in series in the extraction pipe so that the check valve can be opened above the turbine inlet pressure where the thrust load becomes a problem, the operating range where the thrust load is within the allowable range This prevents gas leakage and prevents performance degradation due to such gas leakage.

  Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in this example are not intended to limit the scope of the present invention only to specific examples unless otherwise specified. Only.

FIG. 1 is a longitudinal sectional view of an essential part on the turbine side of an axial exhaust turbocharger according to a first embodiment of the present invention.
In FIG. 1, 10 is a turbine casing, 10b is an exhaust gas inlet passage, 10a is an outlet passage, and 12 is an axial flow type turbine blade, which is attached to the disk portion 12s of the turbine rotor shaft 2 in the circumferential direction. A turbine nozzle 3 is installed at the inlet of the turbine blade 12, and the turbine blade 12 is rotationally driven by an axial exhaust gas flow statically expanded by the turbine nozzle 3.
A compressor 8 (see FIG. 6) is attached to the other end of the turbine rotor shaft 2. The turbine rotor shaft 2 is supported by two radial bearings 16. 1a is a thrust bearing that receives thrust in the turbine axial direction (see FIG. 6).

During the operation of the axial flow type exhaust turbine supercharger having such a configuration, the exhaust gas from the engine (not shown) passes through the exhaust gas inlet passage 10b and is axially exhausted after being statically expanded by the turbine nozzle 3. The turbine blades 12 are rotationally driven by the flow. The exhaust gas that has driven the turbine blades 12 is discharged to the outside from the outlet passage 10a.
The other configurations are the same as those shown in FIG. 6, and the configurations are the same in the following first to fifth embodiments.

In the first embodiment, a space 26 where a leaked gas is accumulated is formed facing the side surface 12t of the turbine rotor shaft 2 on the inner peripheral side of the turbine nozzle 3. Reference numeral 21 denotes a labyrinth seal device for sealing the inside of the space 26. The outer periphery is fixed to the turbine casing 10 by bolts, and the space 26 is sealed to the inner periphery by a labyrinth seal 21a.
Reference numeral 25 denotes an impeller side space facing the disk portion 12s of the turbine rotor shaft 2, and the facing impeller side space 25 communicates with the outlet side of the turbine nozzle 3 through a minute gap 25a.
24 and 23 are through-holes formed in the turbine rotor shaft 2 facing the space 26 and communicating the space 26 and the impeller side space 25, and the through-hole 24 in the axial direction of the turbine rotor shaft 2; A plurality of radial holes 23 pierced radially from the through holes 24 are provided.

According to the first embodiment, the labyrinth seal device 21 that seals the space 26 and the through holes 24 and 23 that communicate the space 26 and the impeller side space 25 with the turbine rotor shaft 2 facing the space 26. Since the gas in the space 26 is configured to be guided to the impeller side space 25 through the through holes 24 and 23,
By providing through holes 24 and 23 communicating with the space 26 and the impeller side space 25 in the turbine rotor shaft 2 facing the space 26, the pumping performance of the through holes 24 and 23 allows the turbine rotor shaft 2 to During rotation, the gas in the radial through hole 23 moves in the radial direction.
As a result, the gas in the space 26 sealed by the labyrinth seal device 21 is sucked out, and the static pressure in the space 26 decreases.

  As the static pressure is reduced, there is a gas that passes through the labyrinth seal device 21 and enters the space. However, the amount of gas discharged from the impeller side space 25 determined by the pumping performance and the labyrinth seal performance is larger. The static pressure in the space 26 is reduced, thereby reducing the thrust load.

FIG. 2 is a longitudinal sectional view of an essential part on the turbine side of an axial exhaust turbocharger according to a second embodiment of the present invention.
In the second embodiment, a plurality of blades 27 are formed at the shaft end of the turbine rotor shaft 2 so as to face the space 26, and a fluid seal is formed on the outer periphery of the blades 27 with a small gap t between the blades 27. A case member 28 is provided. The outer periphery of the case member 28 is fixed to the turbine casing 10 with bolts.
The blade 27 is rotated so that the gas in the space 26 is sucked and guided to the impeller side space 25.

According to the second embodiment, the casing member is formed with a plurality of blades 27 facing the space 26 at the shaft end portion of the turbine rotor shaft 2 and fluidly sealing the blades 27 on the outer peripheral portion of the blades 27. 28, and the blade 27 is rotated so that the gas in the space 26 is sucked and guided to the impeller side space 25.
As a result of the pumping action caused by the rotation of the plurality of blades 27 provided at the shaft end portion of the turbine rotor shaft 12, the gas in the space 26 moves in the radial direction along the blades 27 and reaches the impeller side space 25. The gas in the space 26 partitioned by the case member 28 is sucked out, and the static pressure in the space 26 is reduced.

Since the static pressure is reduced, there is gas that enters the space through the minute gap on the inner periphery of the case member 28, but the gas determined by the pumping performance and tip sealing performance is discharged into the side surface space 25 of the impeller 25. The amount is greater and therefore the static pressure in the space 26 is reduced, thereby reducing the thrust load.
Other configurations are the same as those of the first embodiment, and the same members are denoted by the same reference numerals.

3 is a longitudinal sectional view of the main part of the turbine side of the axial exhaust type turbocharger according to the third embodiment of the present invention.
In the third embodiment, a fixed length screw 31 is formed on the outer periphery of the shaft end of the turbine rotor shaft 2. The screw 31 is formed so that the lead is in the direction of the disk portion 12s as it rotates. Further, a seal member 30 is provided on the outer peripheral portion of the screw 31 to support the screw 31 with a fluid seal. The outer periphery of the seal member 30 is fixed to the turbine casing 10 with bolts. Accordingly, the screw 31 is advanced by the rotation of the turbine rotor shaft 2, so that the gas in the space is guided to the impeller side space 25.

According to the third embodiment, the screw 31 having a fixed length is formed on the outer periphery of the shaft end of the turbine rotor shaft 2, and the seal member 30 is supported on the outer periphery of the screw 31 by the fluid seal. And the gas in the space 26 is guided to the impeller side space 25 as the screw 31 advances as the turbine rotor shaft 2 rotates.
Due to the pumping action caused by the rotation of the screw 31 provided on the outer periphery of the shaft end of the turbine rotor shaft 2, the gas in the screw 31 moves in the axial direction and is discharged to the impeller side space 25. The gas in the partitioned space 26 is sucked out, and the static pressure in the space 26 decreases.

There is a gas that enters the space 26 through a minute gap between the screw 31 and the seal member 30 as the static pressure is reduced, but the gas determined by the pumping performance and the sealing performance of the screw portion enters the side surface space 25 of the impeller. Therefore, the amount of discharged gas is larger, so that the static pressure in the space 26 is lowered, thereby reducing the thrust load.
Other configurations are the same as those of the first embodiment, and the same members are denoted by the same reference numerals.

FIG. 4 is a longitudinal sectional view of an essential part on the turbine side of an axial exhaust turbine supercharger according to a fourth embodiment of the present invention.
In the fourth embodiment, a space 35 is formed in the disk portion 12 s of the turbine rotor shaft 2 where leaked gas accumulates on the side surface of the inner peripheral disk portion 12 s of the turbine nozzle 3. 1 to 3 are included in the space 35.
A through hole 33 is provided to communicate with a lower portion of the space 35 and an impeller outlet portion 12b communicated with the outlet of the turbine blade 12 through a micro passage, and the gas in the space 35 passes through the through hole 33 and the impeller exit. It guides to the part 12b.

According to the fourth embodiment, a very small amount of gas flows from the space 35 side to the turbine through the through hole 33 that communicates the space 35 and the impeller outlet portion 12b that communicates with the outlet of the turbine blade 12 through a minute passage. It is discharged to an impeller outlet portion 12b that communicates with the outlet of the blade 12 through a minute passage.
Along with this, a small amount of gas that has passed through the turbine nozzle 3 is guided to the space upstream of the disk 1 from the gap between the inner ring 3a of the turbine nozzle 3 and the outer edge of the disk 12s.

Here, the gas that has passed through the turbine nozzle 3 has a strong circumferential velocity component. According to the angular momentum conservation measurement, the gas flowing into the space 35 on the upstream side of the disk 12s from the gap between the inner ring 3a of the turbine nozzle 3 and the outer edge of the disk 12s gradually increases the velocity component in the circumferential direction as it moves toward the inner periphery.
As a result, the pressure on the upstream side of the disk 12s, that is, the pressure in the lower portion of the space 35 is greatly reduced on the inner peripheral side compared to the case where a small amount of gas leakage does not occur as described above, thereby reducing the thrust load. .

The gas leakage flow according to this embodiment is generated in an operating state where the thrust load is large, that is, an operating state where the turbocharger rotational speed is high and the turbine inlet pressure is high. On the other hand, under the condition where the turbocharger rotational speed is low and the turbine inlet pressure is low, the difference between the turbine blade 12 inlet pressure and the turbine blade 12 outlet pressure is almost eliminated, and thus this leakage flow does not occur.
Therefore, this example is effective only in an operating state with a large thrust load.
Other configurations are the same as those of the first embodiment, and the same members are denoted by the same reference numerals.

FIG. 5 is a longitudinal sectional view of an essential part on the turbine side of an axial exhaust turbocharger according to a fifth embodiment of the present invention.
In the fifth embodiment, an extraction pipe 36 that communicates the space 35 and the atmosphere similar to the fifth embodiment is provided, and only the flow from the space 35 side to the atmosphere is provided in the extraction pipe 36. A permissible check valve 36b and an orifice 36a are provided in series. The gas in the space 35 is discharged into the atmosphere through the extraction pipe 36.

Therefore, according to the fifth embodiment, a small amount of gas is discharged from the space 35 to the atmosphere through the extraction pipe 36. Along with this, a small amount of gas that has passed through the turbine nozzle 3 is guided to the space 35 upstream of the disk 12s from the gap between the inner ring 3a of the turbine nozzle 3 and the outer edge of the disk 12s.
Here, the gas that has passed through the turbine nozzle 3 has a strong circumferential velocity component. According to the angular momentum conservation measurement, the gas flowing into the space 35 on the upstream side of the disk 12s from the gap between the inner ring 3a of the turbine nozzle 3 and the outer edge of the disk 12s gradually increases the velocity component in the circumferential direction as it moves toward the inner periphery.
As a result, the pressure on the upstream side of the disk, that is, the pressure in the lower portion of the space 35 is greatly reduced on the inner peripheral side as compared with the case where a small amount of gas leakage does not occur as described above, thereby reducing the thrust load.

The gas leakage flow according to the fifth embodiment occurs in an operating state with a large thrust load, that is, an operating state in which the turbocharger rotational speed is high and the turbine inlet pressure is high. On the other hand, under the condition where the turbocharger rotational speed is low and the turbine inlet pressure is low, the difference between the turbine blade inlet pressure and the turbine blade outlet pressure is almost eliminated, so that this leakage flow does not occur.
Therefore, this example is effective only in an operating state with a large thrust load.

Further, if the check valve 36b and the orifice 36a are arranged in series in the extraction pipe 36 so that the check valve 36b is opened above the turbine inlet pressure at which the thrust load becomes a problem, the thrust load is within an allowable range. It is possible to prevent gas from leaking in the operation region inside and to prevent performance deterioration due to such gas leak.
Other configurations are the same as those of the first embodiment, and the same members are denoted by the same reference numerals.

  According to the present invention, there is provided an axial flow turbine thrust reduction device capable of reducing a large thrust load directed from the turbine upstream side to the downstream side to increase the capacity of the exhaust turbine supercharger and increase the pressure ratio of the compressor. Can be provided.

It is a principal part longitudinal cross-sectional view by the side of the turbine of the axial flow type exhaust-turbine supercharger concerning 1st Example of this invention. FIG. 3 is a view corresponding to FIG. 1 showing a second embodiment of the present invention. FIG. 6 is a view corresponding to FIG. 1 showing a third embodiment of the present invention. FIG. 6 is a view corresponding to FIG. 1 showing a fourth embodiment of the present invention. FIG. 10 is a view corresponding to FIG. 1 showing a fifth embodiment of the present invention. It is sectional drawing which follows an axis of rotation which shows an example of an axial flow type exhaust turbine supercharger. It is a thrust load diagram of the supercharger.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Turbine rotor 1a Thrust bearing 2 Turbine rotor axis | shaft 3 Turbine nozzle 8 Compressor 10 Turbine casing 12 Turbine blade 12b Impeller exit part 12s Disk part 16 Radial bearing 21 Labyrinth seal apparatus 23, 24 Through-hole 25 Impeller side space 26 Space 27 Blade 28 Case member 30 Seal member 31 Screw 33 Through hole 35 Space 36 Extraction pipe 36a Orifice 36b Check valve

Claims (6)

A turbine blade driven by an axial exhaust gas flow statically expanded by a turbine nozzle, and a compressor directly connected to the turbine blade via a turbine rotor shaft, the turbine rotor shaft at the inner periphery of the turbine nozzle In the axial turbine turbine thrust reduction device in which a space where leakage gas accumulates is formed on the side surface,
Pressure reducing means for reducing the pressure in the space is provided, and the pressure reducing means is configured to maintain the pressure in the space lower than the pressure in the side surface of the blade wheel communicated with the inlet of the turbine blade through a micro passage. A thrust reduction apparatus for an axial-flow turbine characterized by the above.   The pressure reducing means includes a labyrinth seal device that seals the inside of the space, a turbine rotor shaft that faces the space, and a through hole that communicates the space with the impeller side surface space. The thrust reduction device for an axial-flow turbine according to claim 1, wherein the thrust reduction device is guided to the blade wheel side space through a through hole.   The pressure reducing means includes a plurality of blades facing the space at the shaft end of the turbine rotor shaft, and a case member for fluidly sealing the blades on the outer peripheral portion of the blades. The thrust reduction device for an axial-flow turbine according to claim 1, wherein the gas in the space is sucked and guided to the side surface space of the impeller.   The pressure lowering means is formed with a screw of a fixed length on the outer periphery of the shaft end of the turbine rotor shaft, and provided with a seal member that supports the screw with a fluid seal on the outer periphery of the screw. 2. The thrust reduction device for an axial flow turbine according to claim 1, wherein the gas in the space is guided to the side surface of the impeller by rotating the screw portion by rotation. A turbine blade driven by an axial exhaust gas flow statically expanded by a turbine nozzle, and a compressor directly connected to the turbine blade via a turbine rotor shaft, the turbine rotor shaft at the inner periphery of the turbine nozzle In the axial turbine turbine thrust reduction device in which a space where leakage gas accumulates is formed on the side surface,
The turbine impeller is provided with a through hole that communicates the lower portion of the space and the impeller outlet portion that communicates with the exit of the turbine blade through a minute passage, and the space in the space passes through the through hole to the impeller outlet portion. A thrust reduction apparatus for an axial flow turbine, characterized by being guided. A turbine blade driven by an axial exhaust gas flow statically expanded by a turbine nozzle, and a compressor directly connected to the turbine blade via a turbine rotor shaft, the turbine rotor shaft at the inner periphery of the turbine nozzle In the axial turbine turbine thrust reduction device in which a space where leakage gas accumulates is formed on the side surface,
An axial flow turbine characterized in that an extraction pipe having a check valve and an orifice connected in series is provided to communicate the space and the atmosphere, and gas in the space is discharged to the atmosphere through the extraction pipe. Thrust reduction device.

Images