JP2009174442A - Turbo supercharger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent leakage of an exhaust from a turbine side to a compressor side in a turbo supercharger in which a turbine rotor and a compressor rotor are disposed adjacent to each other. <P>SOLUTION: In the turbo supercharger, a disk rear face 13D of a turbine rotor 13 and a disk rear face 14D of a compressor rotor 14 are faced parallel to each other. The disk rear face 13D and the disk rear face 14D are connected to each other via a cylindrical portion 13C protruding from the disk rear face 13D. A gas seal member 20 having a noncontact labyrinth structure is disposed between the cylindrical portion 13C and a housing connection portion 19. An exhaust leaking into a labyrinth is extracted in or near the middle of the labyrinth via communication pipes 22, 23 and is discharged at or around an outlet of a turbine. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a turbocharger in which a turbine rotor and a compressor rotor are arranged adjacent to each other.

  In a conventional general turbocharger, a shaft that connects a turbine rotor and a compressor rotor is held by a bearing. However, in the configuration in which the bearing is disposed between the turbine rotor and the compressor rotor in this manner, oil supplied to the bearing chamber may leak to the turbine side and cause deterioration in exhaust performance. Further, when the bearing is adjacent to a turbine that is at a high temperature, the deterioration of the oil is promoted, and a malfunction of the turbo due to, for example, oil coking occurs.

On the other hand, a turbocharger having a structure in which a bearing is not provided between the turbine rotor and the compressor rotor but adjacent to each other, the shaft extends further outward from the compressor rotor, and the extended shaft is cantilevered by the bearing. Is also known. In such a configuration, the problem described above is solved by separating the bearing chamber from the turbine. However, since the compressor rotor is adjacent to the turbine rotor, the supercharging efficiency deteriorates due to heat transfer from the turbine side to the compressor side. For this reason, a structure has been proposed in which a heat shield plate having a gap is disposed between the turbine rotor and the compressor rotor to block heat transfer (see Patent Document 1).
Japanese Patent Laid-Open No. 07-180563

  However, in the configuration in which the turbine rotor and the compressor rotor are adjacent to each other, exhaust may leak to the compressor side through the gas seal member on the turbine side. That is, since the turbine capacity is generally configured to be small in order to ensure performance at low speed, the disk back pressure of the turbine rotor greatly exceeds the disk back pressure of the compressor rotor in the high engine load range, and the turbine rotor and compressor There is a possibility that the exhaust leaks out to the compressor side along the shaft connecting the rotor.

  In a configuration in which a bearing is provided between the turbine rotor and the compressor rotor, the leaked exhaust gas is discharged to the crankcase through an oil return communicating from the bearing chamber to the crankcase. However, in the configuration in which the turbine rotor and the compressor rotor are adjacent to each other, the leaked exhaust gas directly flows into the compressor, leading to an increase in the impeller temperature, resulting in a decrease in strength and a deterioration in durability. Further, the wall surface temperature of the diffuser provided at the outlet of the impeller rises, and the oil contained in the blow-by gas adheres to the wall surface, thereby reducing the supercharging efficiency.

  An object of the present invention is to prevent exhaust leakage from a turbine side to a compressor side in a turbocharger in which a turbine rotor and a compressor rotor are arranged adjacent to each other.

  A turbocharger according to the present invention is a turbocharger in which a turbine rotor and a compressor rotor are adjacently arranged coaxially, and a connection portion that connects the turbine rotor and the compressor rotor, and a connection portion housing that covers the connection portion Gas pressure adjusting means for adjusting the gas pressure in the gap provided between the two and preventing exhaust leakage from the turbine to the compressor through the gap, the gas pressure adjusting means bleed the exhaust from the gap, Alternatively, the gas pressure is adjusted by supplying pressurized air to the gap.

  It is preferable to provide a labyrinth for reducing the gas pressure along the turbo rotation axis in the gap. From the viewpoint of reducing exhaust leakage from the turbine, when the gas pressure adjusting means adjusts the gas pressure by extracting air, it is preferable to extract air from a position near the compressor in the labyrinth. On the other hand, when the gas pressure adjusting means adjusts the gas pressure by supplying pressurized air, the pressurized air is preferably supplied from a position near the turbine in the labyrinth.

  The gas pressure adjustment means preferably includes an extraction amount adjustment means for adjusting the amount of extraction from the gap, or a supply amount adjustment means for adjusting the supply amount of pressurized air to the gap. It is possible to perform appropriate extraction or air supply in accordance with the above.

  Further, the gas pressure is preferably adjusted by extracting the exhaust gas from the gap downstream of the turbine when extracting the exhaust gas. When supplying pressurized air, the compressed air downstream of the compressor is supplied to the clearance. It is preferable to adjust by supplying. Thereby, exhaust leakage from the turbine to the compressor can be suppressed with a simpler and smaller configuration.

  As described above, according to the present invention, exhaust leakage from the turbine side to the compressor side can be prevented in the turbocharger in which the turbine rotor and the compressor rotor are disposed adjacent to each other.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view along the turbo rotation axis showing the configuration of the turbocharger according to the first embodiment of the present invention.

  The turbocharger 10 includes a turbine 11 connected to an exhaust manifold and a compressor 12 connected to an intake manifold. The turbine 11 includes a turbine rotor 13 that converts exhaust energy from the engine into rotational force, and the compressor 12 includes a compressor rotor 14 having an impeller. A rotational force is transmitted to the compressor rotor 14 from the turbine rotor 13, whereby the impeller is rotated and supercharging is performed. The turbine rotor 13 is accommodated in the turbine housing 15, and the compressor rotor 14 is accommodated in the compressor housing 16.

  A cylindrical portion 13C having a predetermined length along the rotor rotation axis is coaxially formed in the center of the turbine rotor 13 on the disk rear surface 13D side, and a shaft 17 constituting the rotor rotation shaft is coaxially formed in the cylindrical portion 13C. Attached to. On the other hand, a hole 14H into which the shaft 17 is inserted is formed at the rotation center of the compressor rotor 14. The shaft 17 extends through the hole 14H, and a tip thereof is supported by a bearing portion 18 held by the compressor housing 16. It is pivotally supported.

  The diameter of the cylindrical portion 13C is larger than the diameter of the shaft 17, and the disk back surface 14D side of the compressor rotor 14 fitted and inserted into the shaft 17 is seated on the end surface of the cylindrical portion 13C, and is attached to the shaft 17 and the compressor rotor 14. It is fixed integrally. The cylindrical portion 13C functions as a spacer and a connecting portion between the main body of the turbine rotor 13 and the compressor rotor 14, and when the compressor rotor 14 comes into contact with the end face of the cylindrical portion 13C, the turbine rotor 13 and the compressor rotor 14 The disk back surfaces 13D and 14D are arranged in parallel with each other with a height of the cylindrical portion 13C.

  The length of the cylindrical portion 13 </ b> C is set sufficiently low from the viewpoint of downsizing the turbocharger 10, and the compressor rotor 14 is disposed adjacent to the turbine rotor 13. Therefore, no bearing is provided between the turbine rotor 13 and the compressor rotor 14. That is, the turbine rotor 13, the compressor rotor 14, and the shaft 17 are cantilevered by the bearing portion 18 that supports the tip of the shaft 17.

  The cylindrical portion 13 </ b> C is accommodated in the connecting portion housing 19. The connecting portion housing 19 has, for example, a U-shaped cross section along the disk back surface 13D, the side surface of the cylindrical portion 13C, and the disk back surface 14D, and has a shape that is substantially rotationally symmetric with respect to the rotor rotation axis, for example. The turbine housing 15 and the compressor housing 16 together with the connecting portion housing 19 constitute a housing for the entire turbocharger that houses the turbine rotor 13 and the compressor rotor 14.

  In addition, a certain gap is provided between the connecting portion housing 19 and the outer peripheral surface of the cylindrical portion 13C, and the gas seal member 20 is disposed between the two. The gas seal member 20 is a cylindrical member that covers substantially the entire inner peripheral surface of the cylindrical portion 13C, and a plurality of annular partition plates are provided in parallel on the inner peripheral surface. That is, the gap between the connecting portion housing 19 and the cylindrical portion 13C is partitioned into a plurality of chambers along the axial direction by the gas seal member 20 to form a labyrinth structure.

  FIG. 2 shows a partially enlarged view of the periphery of the gas seal member 20 of FIG. As shown in FIG. 2, a gas seal member 20 is disposed between the connecting portion housing 19 and the outer peripheral surface of the cylindrical portion 13C. The gas seal member 20 is attached to the inner side surface of the connection housing 19 that faces the outer peripheral surface of the cylindrical portion 13C adjacently. Further, as described above, the gap between the connecting portion housing 19 and the outer peripheral surface of the cylindrical portion 13C is formed by the plurality of partition plates 20P extending in an annular shape along the circumferential direction of the inner peripheral surface of the gas seal member 20. And divided into a plurality of rooms along the rotor rotation axis. A slight gap is provided between the tip of the partition plate 20P and the outer peripheral surface of the cylindrical portion 13C so as to be non-contact, and the gas seal member 20 is configured as a non-contact seal. The reason why the non-contact seal is used in the connecting portion housing 19 is that the cylindrical portion 13C integrated with the turbine rotor 13 becomes hot and it is not preferable to use oil.

  In the present embodiment, the inner peripheral edge portion of the partition plate 20P, that is, the tip end portion in the cross-sectional view is formed in a tapered shape. As described above, the tip of the partition plate 20P is disposed with a small gap from the outer peripheral surface of the cylindrical portion 13C. Therefore, if there is a pressure difference between the turbine 11 side and the compressor 12 side, gas flows out from the high pressure side through the gap. The gas passes through a narrow gap between the partition plate 20P and the cylindrical portion 13C, flows into the room partitioned by the partition plate 20P, and this is repeated over a plurality of stages. That is, a pressure loss occurs every time gas passes through each partition plate 20P. Therefore, when the pressure difference between the turbine 11 side and the compressor 12 side is not so large, for example, in a low load region where the air flow rate is small, this labyrinth structure sufficiently suppresses gas leakage from one side to the other side. Is done.

  However, as shown in the graph of FIG. 3, in the high load region where the air flow rate becomes large, the disk back pressure Pt of the turbine rotor 13 becomes remarkably higher than the disk back pressure Pc of the compressor rotor 14, and both back surfaces The pressure difference increases. When this pressure difference exceeds a range that can be reduced by the plurality of partition plates 20P of the gas seal member 20, the exhaust gas leaks from the turbine 11 side to the compressor 12 side. That is, the exhaust on the turbine 11 side passes through the gap between the partition plate 20P and the cylindrical portion 13C along the cylindrical portion 13C from the gap between the disc rear surface 13D and the connecting portion housing 19, and the lower pressure disk rear surface 14D. Flow toward the side.

  Therefore, in the first embodiment, an exhaust port 20H is provided in the middle of the gas seal member 20 (intermediate part of the labyrinth), and the exhaust gas flowing out from the turbine 11 side when the pressure difference between the turbine 11 side and the compressor 12 side is large. Is extracted to adjust the pressure in the labyrinth to prevent exhaust leakage to the compressor 12 side. That is, the gas seal member 20 is provided with a bleed port 20H in a part of the partitioned room (for example, one of the bays), and a communication hole 19H is provided at a position corresponding to the bleed port 20H of the connecting portion housing 19. It is done. The communication hole 19H communicates with the vicinity of the turbine outlet via a communication pipe, and a relief valve 21 (see FIG. 1) is provided in the middle of the communication pipe.

,
The relief valve 21 starts to gradually open when the pressure at the extraction port 20H becomes higher than the pressure near the turbine outlet and the pressure difference becomes larger than a predetermined value, and exhaust gas leaking from the turbine 11 side is discharged from the extraction port 20H to the turbine. Bleed to the exit. More specifically, a communication pipe 22 connected to a relief valve 21 as shown in FIG. 1 is connected to the communication hole 19H, and the relief valve 21 is further connected to a turbine outlet near a turbine outlet via a communication pipe 23. It is connected to the hole 15H. The relief valve 21 is urged by an urging means such as a spring so that the valve body resists the pressure from the communication pipe 22 on the bleed port 20H side. The urging force is, for example, an adjustment screw (not shown). By adjusting means such as the above, adjustment is performed so that a necessary amount of extraction can be performed according to the pressure of the exhaust gas leaking into the labyrinth.

  As shown in FIG. 3, in the low load region, the pressure on the compressor 12 side is higher than the pressure on the turbine 11 side, so the pressure on the compressor 12 side is dominant in the vicinity of the extraction port 20H. Therefore, the urging force of the relief valve 21 is adjusted so that the relief valve 21 is kept closed against the pressure in the vicinity of the extraction port 20H in the low load region. Furthermore, the urging force of the relief valve 21 becomes so high that the pressure on the turbine 11 side is higher than the pressure on the compressor 12 side in the high load region to the extent that the labyrinth structure cannot prevent exhaust leakage, and the turbine 11 near the extraction port 20H. Adjusted to open when side pressure becomes dominant.

  1 and 2, the position of the bleed port 20 </ b> H is depicted as being arranged slightly closer to the compressor than the center of the gas seal member 20, but in order to reduce the exhaust leakage from the turbine 11 to the labyrinth, the bleed port It is preferable to arrange 20H closer to the compressor 12 side. That is, when the extraction port 20H is provided near the turbine 11, more exhaust gas is extracted because the gas pressure in the vicinity of the extraction port 20H is high, and exhaust leakage from the turbine 11 to the labyrinth increases. Therefore, it is possible to suppress unnecessary extraction by performing extraction from the position where the gas pressure is reduced by the labyrinth, and to reduce the amount of exhaust leaking from the turbine 11 to the labyrinth. In the high load range where the exhaust is excessive, the exhaust is released to the downstream side of the turbine via a wastegate valve (not shown), so the influence on the turbo performance due to the extraction from the labyrinth is substantial. Not.

  As described above, according to the first embodiment, air is extracted from the gap between the connecting portion that connects the turbine rotor and the compressor rotor and the housing, and the pressure of the gap is adjusted by adjusting the amount of extraction. Exhaust leakage to the compressor side is prevented. Further, by providing a labyrinth structure in the gap and communicating the labyrinth with the turbine downstream, it is possible to perform extraction for preventing exhaust leakage with a very simple configuration. Furthermore, by providing a relief valve in the communication pipe, it becomes possible to perform pressure adjustment more appropriately.

  Next, a second embodiment of the present invention will be described with reference to FIGS. The configuration of the turbocharger of the second embodiment is substantially the same as that of the first embodiment, but in the second embodiment, the bleed air from the labyrinth in the first embodiment is used as pressurized air from the compressor outlet to the labyrinth. It has been replaced with the introduction of. Since the basic configuration of the turbocharger of the second embodiment is the same as that of the first embodiment, the description thereof is omitted, and the same reference numerals are used for the same configurations.

  In the high load region, the outlet pressure of the compressor 12 is at the same level as the disk back pressure of the turbine rotor 13. Therefore, in the turbocharger 30 of the second embodiment, pressurized air is supplied from the outlet of the compressor 12 to the labyrinth.

  The gas seal member 20 is provided with an air introduction port 27 in a part of a room (for example, one of the compartments) partitioned by the partition plate 20P, similarly to the extraction port 20H in the first embodiment. A communication hole 26 is provided at a position corresponding to the air introduction port 27 of the connection portion housing 19, and communicates with a communication hole 16 </ b> H provided near the compressor outlet via the communication pipe. A relief valve 21 is provided in the middle of the communication pipe. That is, as shown in FIG. 4, the relief valve 21 is connected to the communication hole 26 of the connection portion housing 19 via the communication pipe 24, and to the communication hole 16 </ b> H provided in the compressor housing 16 via the connection pipe 25. Connected.

  The relief valve 21 is connected to the connection pipes 24 and 25 in such a direction that the valve closes against the air pressure from the compressor 12 side. In a high load region where the disk back pressure of the turbine rotor 13 is larger than the disk back pressure of the compressor rotor 14, the pressure near the compressor outlet where the communication hole 16 </ b> H is provided reaches a level equal to or higher than the disk back pressure of the turbine rotor 13. To rise. Therefore, when the pressure in the vicinity of the communication hole 16H becomes higher than the pressure in the vicinity of the air introduction port 27 in the labyrinth, the relief valve 21 is opened, and pressurized air is supplied from the compressor 12 to the labyrinth of the gas seal member 20. As a result, the exhaust gas leaking from the turbine 11 side to the labyrinth of the gas seal member 20 is pushed back by the pressurized air supplied from the air introduction port 27, and the exhaust leak from the turbine 11 side is prevented. The amount of air supplied to the labyrinth is adjusted by adjusting the urging force of the relief valve 21 as in the first embodiment.

  The air supplied from the air inlet 27 to the labyrinth leaks to the disk back surface 14D side of the compressor rotor 14 that is relatively low in pressure thereafter. Since this leakage amount is extracted from the air to be supplied from the compressor 12 to the engine, it is desirable that the leakage amount be as small as possible from the viewpoint of supercharging efficiency.

  Therefore, in 2nd Embodiment, as FIG. 5 shows, the air inlet 27 of the gas seal member 20 is provided near the turbine side as much as possible. That is, by increasing the number of labyrinth stages from the air inlet 27 to the disk back surface 14D of the compressor rotor 14, the amount of air extracted from the compressor outlet is suppressed. In FIG. 4, the positions of the air introduction port 27 and the communication hole 26 are drawn in the approximate center of the gas seal member 20, but FIG. 4 schematically shows the connection of the connecting pipe from the compressor outlet to the labyrinth. And does not correctly indicate the position of the air inlet 27.

  As described above, even in the configuration of the second embodiment, the pressurized air is supplied from the compressor outlet side to the gap of the connecting portion that connects the turbine rotor and the compressor rotor, so that the connection is performed in the same manner as in the first embodiment. By adjusting the pressure in the gap provided in the section, exhaust leakage from the turbine side to the compressor side can be prevented. Moreover, in 2nd Embodiment, the heat transfer through a connection part can be suppressed according to the cooling effect by the air supplied to the clearance gap between connection parts, and reliability can further be improved.

  In the present embodiment, the cylindrical portion (connecting portion) that connects the turbine rotor and the compressor rotor is configured as a part of the turbine rotor. However, it may be integrated with the compressor rotor or may be an independent member. is there. Further, the labyrinth structure is not limited to the present embodiment, and any other configuration may be used as long as decompression is performed. Moreover, the structure which provides a partition plate in the connection part side instead of the housing side may be sufficient.

It is sectional drawing along the turbo rotating shaft which shows the structure of the turbocharger which is 1st Embodiment of this invention. It is a partial enlarged view of the gas seal member periphery of 1st Embodiment. It is a graph which shows the value of the disk back pressure Pt of the turbine rotor with respect to an air flow rate, and the value of the disk back pressure Pc of a compressor rotor. It is sectional drawing along the turbo rotating shaft which shows the structure of the turbocharger which is 2nd Embodiment of this invention. It is the elements on larger scale around the gas seal member of a 2nd embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Turbocharger 11 Turbine 12 Compressor 13 Turbine rotor 13C Cylindrical part (connection part)
DESCRIPTION OF SYMBOLS 14 Compressor rotor 15 Turbine housing 15H Communication hole 16 Compressor housing 16H Communication hole 17 Shaft 18 Bearing part 19 Connection part housing 20 Gas seal member 20H Extraction port 27 Air introduction port 20P Partition plate 21 Relief valve 22-25 Communication pipe

Claims (8)

A turbocharger in which a turbine rotor and a compressor rotor are adjacently arranged coaxially,
A gas pressure in a gap provided between a connecting portion that connects the turbine rotor and the compressor rotor and a connecting portion housing that covers the connecting portion is adjusted, and exhaust leakage from the turbine to the compressor through the gap is prevented. Gas pressure adjusting means,
The turbocharger, wherein the gas pressure adjusting means adjusts the gas pressure by extracting the exhaust gas from the gap or supplying pressurized air to the gap.   The turbocharger according to claim 1, wherein a labyrinth for reducing the gas pressure is provided in the gap along the turbo rotation shaft.   The turbocharger according to claim 2, wherein the gas pressure adjusting means adjusts the gas pressure by extraction, and the extraction is performed from a position near the compressor in the labyrinth.   The turbocharger according to claim 2, wherein the gas pressure adjusting means adjusts the gas pressure by supplying pressurized air, and the pressurized air is supplied from a position near the turbine in the labyrinth. Feeder.   The turbocharger according to any one of claims 1 to 3, wherein the gas pressure adjusting means includes an extraction amount adjusting means for adjusting an extraction amount from the gap.   5. The turbo excess according to claim 1, wherein the gas pressure adjusting means includes supply amount adjusting means for adjusting a supply amount of pressurized air to the gap. Feeder.   The turbocharger according to any one of claims 1, 2, 3, and 5, wherein the gas pressure is adjusted by extracting the exhaust gas from the gap to the turbine downstream. .   The turbocharger according to any one of claims 1, 2, 4, and 6, wherein the gas pressure is adjusted by supplying pressurized air downstream of a compressor to the gap. Machine.

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