Turbocharger

Abstract

A turbocharger according to the present invention comprises: a shaft 2; an impeller 3 provided at one end of the shaft 2; a bearing B that rotatably supports the shaft 2; and a housing that includes a bearing hole 51 for accommodating the bearing B, and also includes a space S3 between the bearing hole 51 and the impeller 3, and a communication passage 53 that connects the space S3 to a region having a pressure lower than the pressure in the space S3.

Description

turbocharger

[0001] This application claims the benefit of priority from Japanese Patent Application No. 2024-101775, filed on June 25, 2024, the contents of which are incorporated herein by reference.

[0002] In turbochargers, a seal may be placed between the impeller and the bearing bore. However, gas flowing through the passage that houses the impeller may leak through the seal into the bearing housing. This can lead to various problems.

[0003] For example, when a turbocharger is connected to a hydrogen engine, the exhaust gas flowing through the turbine may contain a large amount of water vapor. If such exhaust gas leaks from the turbine into the bearing housing and mixes with the oil, the oil's performance may change due to the emulsion. Furthermore, the leaked gas may flow into the engine's oil pan through the turbocharger's oil drain, increasing the internal pressure of the oil pan and reducing the engine's operating efficiency.

[0004] For example, Patent Document 1 discloses a turbocharger that addresses such problems. In this turbocharger, an air chamber is formed in a position defined by a turbine and a seal member. An air passage connecting to the air chamber is formed from the volute chamber of the compressor. When the engine is operating at high speed and under high load, compressed air from the compressor is supplied to the air chamber from the volute chamber via the air passage. The compressed air maintains the turbine, which is pressed by the exhaust gas, in a fixed position. This prevents exhaust gas leakage.

[0005] Japanese Patent Application Laid-Open No. 2002-70569

[0006] For example, in Patent Document 1, there is a possibility that compressed air supplied from an air passage may be mixed with exhaust gas flowing through the turbine. Generally, an A / F sensor (air-fuel ratio sensor) or an O ２ A sensor is placed and the amount of fuel injected is adjusted based on the sensor reading. However, when the compressed air mixes with the exhaust gas flowing through the turbine, the A / F sensor or O ２The sensor readings may change, making it impossible to adjust the amount of fuel injected as intended.

[0007] An object of the present disclosure is to provide a turbocharger that can reduce gas leakage into a bearing housing.

[0008] In order to solve the above problems, a turbocharger according to one aspect of the present disclosure includes a housing including a shaft, an impeller provided at one end of the shaft, a bearing that rotatably supports the shaft, and a bearing hole that accommodates the bearing, the housing including a space between the bearing hole and the impeller, and a communication passage that connects the space to a region having a pressure lower than the pressure of the space.

[0009] The communication passage may be in fluid communication with a flow path of air drawn into a compressor impeller of the supercharger.

[0010] The intake pipe connected to the centrifugal compressor of the turbocharger may be provided with a throttle valve located downstream of the centrifugal compressor, and the communication passage may be fluidly connected to the intake pipe at a position downstream of the throttle valve.

[0011] The turbocharger may include a first seal ring and a second seal ring arranged in a space between the bearing hole and the turbine impeller and spaced apart along the axial direction of the shaft, and the communication passage may be fluidly connected to the space between the first seal ring and the second seal ring.

[0012] The supercharger may be connected to the hydrogen engine.

[0013] According to the present disclosure, gas leakage into the bearing housing can be reduced.

[0014] Fig. 1 is a schematic cross-sectional view of a turbocharger according to an embodiment, and Fig. 2 is a schematic enlarged cross-sectional view of a portion A in Fig. 1.

[0015] An embodiment of the present disclosure will be described below with reference to the accompanying drawings. Specific dimensions, materials, numerical values, etc. shown in the embodiment are merely examples for ease of understanding and do not limit the present disclosure unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation, and elements not directly related to the present disclosure are not shown.

[0016] FIG. 1 is a schematic cross-sectional view of a turbocharger TC according to an embodiment. In this embodiment, the turbocharger TC is connected to an engine 100. For example, in this embodiment, the engine 100 is a hydrogen engine. In other embodiments, the engine 100 may be another engine, such as a gasoline engine or a diesel engine. For example, in this embodiment, the engine 100 may be a spark-ignition engine. In this case, a throttle valve V1 is provided in the intake pipe L1. In other embodiments, the engine 100 may be a compression-ignition engine. In this case, the throttle valve V1 is not necessary.

[0017] The centrifugal compressor C of the supercharger TC is provided on an intake pipe L1 leading to the engine 100. The turbine T of the supercharger TC is provided on an exhaust pipe L2 leading from the engine 100.

[0018] For example, the turbocharger TC includes a housing 1 , a shaft 2 , a turbine impeller 3 , and a compressor impeller 4 .

[0019] As will be described later, the turbine impeller 3 and the compressor impeller 4 rotate integrally with the shaft 2. Therefore, in the present disclosure, the axial direction, radial direction, and circumferential direction of the shaft 2, the turbine impeller 3, and the compressor impeller 4 may be simply referred to as the "axial direction," the "radial direction," and the "circumferential direction," respectively, unless otherwise specified. Also, in the present disclosure, the axis of the shaft 2, the turbine impeller 3, and the compressor impeller 4 may be simply referred to as the "axis" unless otherwise specified.

[0020] The housing 1 includes a bearing housing 5, a turbine housing 6, and a compressor housing 7. One end of the bearing housing 5 in the axial direction is connected to the turbine housing 6. The other end of the bearing housing 5 in the axial direction is connected to the compressor housing 7.

[0021] The bearing housing 5 includes a bearing hole 51. The bearing hole 51 extends in the axial direction within the bearing housing 5. The bearing hole 51 accommodates a bearing B. The inner circumferential surface of the bearing hole 51 supports the bearing B in the radial direction. The bearing B rotatably supports the shaft 2. In this embodiment, a semi-floating bearing is used as the bearing B. In other embodiments, for example, a full-floating bearing or another radial bearing such as a rolling bearing may be used as the bearing B. The shaft 2 passes through the bearing hole 51.

[0022] The bearing housing 5 includes an oil passage 52. The oil passage 52 extends from the outer wall of the bearing housing 5 to the bearing hole 51. Oil is supplied to the bearing hole 51 through the oil passage 52 by an oil pump (not shown). The bearing B is lubricated by the oil.

[0023] A turbine impeller 3 is provided at a first end of the shaft 2 in the axial direction. The turbine impeller 3 rotates integrally with the shaft 2. The turbine housing 6 defines a first space S1 that houses the turbine impeller 3.

[0024] A compressor impeller 4 is provided at a second end of the shaft 2 opposite the first end in the axial direction. The compressor impeller 4 rotates integrally with the shaft 2. The compressor housing 7 defines a second space S2 that houses the compressor impeller 4.

[0025] The compressor housing 7 includes an air intake port 71 at an end axially opposite to the bearing housing 5. The air intake port 71 is in fluid communication with an air cleaner (not shown) via an intake pipe L1.

[0026] The bearing housing 5 and the compressor housing 7 define a diffuser passage 72 therebetween. The diffuser passage 72 has an annular shape. The diffuser passage 72 is located radially outward from the compressor impeller 4. The diffuser passage 72 is in fluid communication with the intake port 71 via the compressor impeller 4.

[0027] The compressor housing 7 includes a compressor scroll passage 73. The compressor scroll passage 73 is located radially outward of the diffuser passage 72. The compressor scroll passage 73 is connected to the diffuser passage 72. The compressor scroll passage 73 is also in fluid communication with the intake port of the hydrogen engine 100 via an intake pipe L1.

[0028] When the compressor impeller 4 rotates, air is drawn into the compressor housing 7 through the intake port 71. The air is accelerated and pressurized by centrifugal force while passing through the compressor impeller 4. The air is further pressurized as it passes through the diffuser passage 72 and flows into the compressor scroll passage 73. The compressed air is led to the intake port of the hydrogen engine 100 via the intake pipe L1. In the turbocharger TC, the portion including the compressor impeller 4 and the compressor housing 7 functions as a centrifugal compressor C.

[0029] The turbine housing 6 includes a discharge port 61 at an end opposite to the bearing housing 5 in the axial direction. The discharge port 61 is connected to an exhaust gas purification device (not shown) via an exhaust pipe L2.

[0030] The turbine housing 6 includes a flow passage 62. The flow passage 62 has an annular shape. The flow passage 62 is located radially outward from the turbine impeller 3. The flow passage 62 is in fluid communication with the discharge port 61 via the turbine impeller 3.

[0031] The turbine housing 6 includes a turbine scroll passage 63. The turbine scroll passage 63 is located radially outward of the passage 62. The turbine scroll passage 63 is connected to the passage 62. The turbine scroll passage 63 is also in fluid communication with the exhaust port of the hydrogen engine 100 via an exhaust pipe L2, and receives exhaust gas from the hydrogen engine 100.

[0032] Exhaust gas is guided from the hydrogen engine 100 to the turbine scroll passage 63, and further to the discharge port 61 via the passage 62 and the turbine impeller 3. The exhaust gas rotates the turbine impeller 3 as it passes through it. The rotational force of the turbine impeller 3 is transmitted to the compressor impeller 4 via the shaft 2. When the compressor impeller 4 rotates, the air is compressed as described above. In this way, the compressed air is supplied to the hydrogen engine 100. In the turbocharger TC, a portion including the turbine impeller 3 and the turbine housing 6 functions as the turbine T.

[0033] The bearing hole 51 is fluidly separated from the first space S1 that houses the turbine impeller 3 by a seal 80. The seal 80 is disposed in a space (third space) between the bearing hole 51 and the turbine impeller 3 in the axial direction. The bearing hole 51 is blocked by the seal 80 from the exhaust gas flowing through the first space S1. The seal 80 will be described in detail later.

[0034] The bearing hole 51 is fluidly separated from the second space S2, which accommodates the compressor impeller 4, by a seal 90. The seal 90 is disposed in a space (fourth space) between the bearing hole 51 and the compressor impeller 4 in the axial direction. The seal 90 blocks the bearing hole 51 from air flowing through the second space S2. From another perspective, the bearing housing 5 defines a space (fifth space) S5 that is fluidly separated from the first space S1 and the second space S2 by the seals 80 and 90. In this embodiment, the space S5 extends in the axial direction from the seal 80 to the seal 90. That is, in this embodiment, the space S5 is a region that is longer than the bearing hole 51 and includes the bearing hole 51.

[0035] FIG. 2 is a schematic enlarged cross-sectional view of part A in FIG.

[0036] As described above, the space S5 is fluidly separated from the first space S1 that accommodates the turbine impeller 3 by the seal 80. The seal 80 is disposed in the third space S3 between the bearing hole 51 and the turbine impeller 3 in the axial direction.

[0037] In the present embodiment, the seal 80 includes a first seal ring 81 and a second seal ring 82. The first seal ring 81 and the second seal ring 82 are arranged in the third space S3 and spaced apart from each other along the axial direction. For example, the first seal ring 81 is arranged closer to the turbine impeller 3 than the second seal ring 82. The second seal ring 82 is arranged closer to the bearing hole 51 than the first seal ring 81.

[0038] For example, each of the first seal ring 81 and the second seal ring 82 may be a C-type seal ring. A C-type seal ring has a generally circular shape when viewed in the axial direction, but is discontinuous at a certain position in the circumferential direction. Therefore, the C-type seal ring may include a gap at a certain position in the circumferential direction. For example, each of the first seal ring 81 and the second seal ring 82 is inserted into a groove formed in the outer surface of the shaft 2.

[0039] For example, if the first seal ring 81 and the second seal ring 82 are each a C-type seal ring, the exhaust gas flowing through the first space S1 of the turbine T may leak into the space S5 through the gap. As described above, in this embodiment, the turbocharger TC is connected to the hydrogen engine 100. Therefore, the exhaust gas may contain a large amount of water vapor. In this case, if the exhaust gas mixes with the oil in the space S5, the emulsion may change the performance of the oil.

[0040] In this embodiment, to reduce leakage of exhaust gas from the first space S1 to the fifth space S5, the housing 1 includes a communication passage 53. The communication passage 53 connects the third space S3 to a region having a pressure lower than the pressure of the third space S3.

[0041] Specifically, in this embodiment, the communication passage 53 and the third space S3 are formed in the bearing housing 5. The communication passage 53 includes an opening 54 facing the third space S3. In this embodiment, the opening 54 faces radially inward. The orientation of the opening 54 is not limited thereto. In this embodiment, the communication passage 53 passes through the bearing housing 5, and the opening 54 is in fluid communication with the outside of the bearing housing 5. For example, in other embodiments, the communication passage 53 and the third space S3 may be formed in the turbine housing 6.

[0042] In this embodiment, the opening 54 is located axially between the first seal ring 81 and the second seal ring 82. Therefore, the communication passage 53 is in fluid communication with the space between the first seal ring 81 and the second seal ring 82.

[0043] 1 , the communication passage 53 is connected to a suction conduit L3. The suction conduit L3 extends outside the housing 1. In this embodiment, the suction conduit L3 branches into a first conduit L31 and a second conduit L32. For example, a three-way valve V2 may be provided at the branch point between the first conduit L31 and the second conduit L32.

[0044] The first conduit L31 is fluidly connected to the flow path of air drawn into the compressor impeller 4. In this embodiment, the first conduit L31 is connected to the intake pipe L1 at a position P1 upstream of the centrifugal compressor C. At position P1, air is drawn into the compressor impeller 4. Therefore, the pressure in the intake pipe L1 at position P1 is negative. Therefore, the pressure in the intake pipe L1 at position P1 is lower than the pressure in the third space S3. With this configuration, gas in the third space S3 is drawn into the intake pipe L1 via the communication passage 53, the suction conduit L3, and the first conduit 31. Therefore, exhaust gas flowing from the first space S1 toward the fifth space S5 is drawn into the communication passage 53. This reduces leakage of exhaust gas from the first space S1 to the fifth space S5.

[0045] In another embodiment, the first conduit L31 may be directly connected to the centrifugal compressor C at a position upstream of the compressor impeller 4.

[0046] The second conduit L32 is fluidly connected to the intake pipe L1 at a position P2 downstream of the throttle valve V1 in the flow of compressed air from the compressor impeller 4. For example, the second conduit L32 may be connected to a surge tank (not shown) between the throttle valve V1 and the engine 100 in the intake pipe L1. For example, when the throttle valve V1 is closed, the air suction by the compressor impeller 4 is weakened. Therefore, the air suction at the position P1 is weakened. However, in this case, because the throttle valve V1 is closed, the pressure in the intake pipe L1 at the position P2 is negative due to the negative pressure in the combustion chamber of the engine 100. Therefore, when the throttle valve V1 is closed, the pressure in the intake pipe L1 at the position P2 is lower than the pressure in the third space S3 and lower than the pressure in the intake pipe L1 at the position P1. With this configuration, when the throttle valve V1 is closed, gas in the third space S3 is drawn into the intake pipe L1 via the communication passage 53, the suction conduit L3, and the second conduit 32. Therefore, even when the throttle valve V1 is closed, exhaust gas flowing from the first space S1 toward the fifth space S5 is drawn into the communication passage 53. This reduces the leakage of exhaust gas from the first space S1 to the fifth space S5.

[0047] For example, an ECU (Electronic Control Unit) (not shown) may control the opening and closing of the first conduit L31 and the second conduit L32 by the three-way valve V2 in accordance with the opening of the throttle valve V1.

[0048] If the engine 100 is a compression ignition engine and does not have a throttle valve V1, the second conduit L32 is not necessary. In this case, the suction conduit L3 may be directly connected to the position P1, or may be directly connected to the centrifugal compressor C at a position upstream of the compressor impeller 4.

[0049] In another embodiment, the suction conduit L3 may be connected to a suction device such as a vacuum pump. With this configuration, the exhaust gas flowing from the first space S1 toward the fifth space S5 can be sucked through the communication passage 53.

[0050] As described above, the turbocharger TC according to this embodiment includes the shaft 2, the turbine impeller 3 provided at one end of the shaft 2, the bearing B that rotatably supports the shaft 2, and the housing 1 including the bearing hole 51 that accommodates the bearing B. The housing 1 includes the third space S3 between the bearing hole 51 and the turbine impeller 3, and the communication passage 53 that connects the third space S3 to a region having a pressure lower than that of the third space S3. With this configuration, as described above, exhaust gas flowing from the first space S1 toward the fifth space S5 is sucked through the communication passage 53 by the region having a pressure lower than that of the third space S3. This reduces the leakage of exhaust gas from the first space S1 into the bearing housing 5. This prevents a decrease in the operating efficiency of the turbocharger TC. Furthermore, with this configuration, compressed air is not mixed with the exhaust gas, as in Patent Document 1. Therefore, the exhaust gas is not mixed with the A / F sensor or O ２ The sensor readings are not changed.

[0051] Furthermore, in the turbocharger TC, the communication passage 53 is fluidly connected to a flow path of air drawn into the compressor impeller 4, which in this embodiment is the position P1 of the intake pipe L1. With this configuration, for example, there is no need to add a suction device such as a vacuum pump, and therefore it is possible to suppress an increase in costs.

[0052] Furthermore, in the turbocharger TC, an intake pipe L1 connected to the centrifugal compressor C is provided with a throttle valve V1 located downstream of the centrifugal compressor C, and the communication passage 53 is fluidly connected to the intake pipe L1 at a position P2 downstream of the throttle valve V1. With this configuration, when the throttle valve V1 is closed, the pressure in the intake pipe L1 at the position P2 is lower than the pressure in the intake pipe L1 at the position P1. Therefore, when the throttle valve V1 is closed, exhaust gas is drawn into the position P2.

[0053] The turbocharger TC also includes a first seal ring 81 and a second seal ring 82 that are arranged apart from each other in the axial direction in a third space S3 between the bearing hole 51 and the turbine impeller 3, and the communication passage 53 is fluidly connected to the space between the first seal ring 81 and the second seal ring 82. This configuration can reduce the leakage of exhaust gas from the first space S1 to the fifth space S5, while preventing the communication passage 53 from excessively suctioning exhaust gas and preventing the communication passage 53 from suctioning oil in the fifth space S5.

[0054] The turbocharger TC is connected to the hydrogen engine. With this configuration, it is possible to suppress changes in oil performance due to emulsion caused by water vapor contained in exhaust gas.

[0055] While one embodiment of the present disclosure has been described above with reference to the accompanying drawings, it goes without saying that the present disclosure is not limited to such an embodiment. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that such modifications also fall within the technical scope of the present disclosure.

[0056] For example, in the above embodiment, the turbocharger TC includes the first seal ring 81 and the second seal ring 82. In other embodiments, the turbocharger TC may include only one of the first seal ring 81 and the second seal ring 82. For example, in other embodiments, the turbocharger TC may not include the first seal ring 81. In this case, the turbocharger TC may have some kind of obstacle, such as a labyrinth or a mesh, between the first space S1 and the second seal ring 82 to reduce the flow of exhaust gas, in order to prevent the communication passage 53 from excessively drawing in exhaust gas.

[0057] Also, for example, in the above embodiment, the communication passage 53 is provided for the third space S3 between the bearing hole 51 and the turbine impeller 3. Alternatively or additionally, in other embodiments, a communication passage may be provided for the space (fourth space) between the bearing hole 51 and the compressor impeller 4. With this configuration, for example, when the exhaust gas is recirculated to the intake pipe L1, it is possible to reduce leakage of exhaust gas from the second space S2 to the fifth space S5. In this case, the communication passage and the fourth space may be formed in the bearing housing 5 or the compressor housing 7.

[0058] The present disclosure provides ２ It can promote the use of hydrogen, which leads to reduced emissions, thereby contributing, for example, to Sustainable Development Goal (SDG) 7 "Ensure access to affordable, reliable, sustainable and modern energy" and SDG 13 "Take urgent action to combat climate change and its impacts."

[0059] REFERENCE SIGNS LIST 1 Housing 2 Shaft 3 Turbine impeller 4 Compressor impeller 51 Bearing hole 53 Communication passage 81 First seal ring 82 Second seal ring 100 Engine B Bearing C Centrifugal compressor L1 Intake pipe P2 Position downstream of throttle valve in intake pipe S3 Third space (space between bearing hole and impeller) TC Supercharger V1 Throttle valve

Claims

1. A turbocharger comprising: a shaft; an impeller provided at one end of the shaft; a bearing that rotatably supports the shaft; and a housing including a bearing hole that accommodates the bearing, the housing including: a space between the bearing hole and the impeller; and a communication passage that connects the space to a region having a pressure lower than the pressure of the space.

2. The turbocharger according to claim 1, wherein the communication passage is in fluid communication with a flow path of air drawn into a compressor impeller of the turbocharger.

3. A turbocharger according to claim 2, wherein an intake pipe connected to a centrifugal compressor of the turbocharger is provided with a throttle valve located downstream of the centrifugal compressor, and the communication passage is in fluid communication with the intake pipe at a position downstream of the throttle valve.

4. The turbocharger according to claim 1, further comprising a first seal ring and a second seal ring disposed in the space between the bearing hole and the impeller and spaced apart along the axial direction of the shaft, and the communication passage is in fluid communication with the space between the first seal ring and the second seal ring.

5. The turbocharger according to claim 1, wherein the turbocharger is connected to a hydrogen engine.

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