Recessed compressor wheel for turbocharger oil leakage mitigation

Abstract

A recessed compressor wheel for turbocharger oil leakage mitigation is disclosed. A turbocharger includes a compressor section having a compressor housing with an air inlet and a compressor air outlet, and a compressor wheel in the compressor housing. A turbine section has a turbine housing with a discharge gas inlet and a turbine discharge gas outlet, and a turbine wheel in the turbine housing drivingly connected to the compressor wheel. The discharge gas inlet is configured to be connected to an engine discharge passage, and the turbine discharge gas outlet is configured to be connected to an exhaust system. The compressor housing includes a diffuser having a recess receiving the compressor wheel, wherein the recess has a sidewall with an upper edge, and the compressor wheel has a floor with an upper surface below the upper edge of the sidewall of the recess in the diffuser.

Description

[0001] The information provided in this section is for the purpose of presenting the overall context of this disclosure. The work of the currently attributed inventors, to the extent described in this section, and in all aspects of that description which at the time of filing may not be regarded as prior art, is neither expressly nor implicitly considered prior art to this disclosure. Technical Field

[0002] This disclosure relates to a turbocharger, and more particularly to a turbocharger having a recessed compressor impeller for oil leakage mitigation. Background Technology

[0003] A compressor pre-throttle valve is used in engines to alleviate icing of the turbocharger air cooler and to purge the fuel tank of the large gasoline tank. The use of this compressor pre-throttle valve creates a vacuum on the compressor side of the annular seal between the turbocharger compressor housing and the bearing housing, resulting in oil leakage from the bearing housing to the compressor housing.

[0004] The design of a standard turbocharger aligns the compressor impeller with the diffuser edge / geometry of the compressor backplate, resulting in an increase in ambient or higher air pressure behind the compressor impeller with increasing turbocharger speed. This causes gas blown by the compressor ring seals to move from the compressor housing into the bearing housing and then into the engine crankcase. However, the vacuum created by the compressor front throttle valve imposes a pressure lower than the crankcase pressure behind the compressor impeller, especially at low compressor impeller speeds, where the pressure generated by the impeller is not high enough to negate the vacuum created by the compressor front throttle valve. If the air pressure behind the compressor impeller is lower than the bearing housing (i.e., engine crankcase) pressure, engine oil will leak across the compressor seals into the compressor housing, eventually being absorbed by the engine or leaking from the turbocharger air cooler piping. Summary of the Invention

[0005] This disclosure relates to a turbocharger including a compressor section having a compressor housing and a compressor impeller within the compressor housing, the compressor housing having an air inlet and a compressor air outlet. A turbine section includes a turbine housing and a turbine impeller within the turbine housing, the turbine housing having an exhaust gas inlet and a turbine exhaust gas outlet. The turbine impeller is drivably connected to the compressor impeller. The exhaust gas inlet is configured to connect to an engine exhaust passage, and the turbine exhaust gas outlet is configured to connect to an exhaust system. The compressor housing includes a diffuser having a recess for receiving the compressor impeller, wherein the recess has a sidewall with an upper edge, and the compressor impeller has a base plate with an upper surface below the upper edge of the sidewall of the recess in the diffuser.

[0006] By recessing the compressor impeller into the compressor backplate, the boost pressure generated by the compressor impeller is used to increase the pressure on the compressor side of the annular seal, thereby mitigating oil leakage. Specific geometry near the diffuser reduces the required impeller recess height.

[0007] The novel shape of the compressor backplate and its optimized interaction with the compressor impeller maximize the pressure behind the compressor impeller while minimizing the impact on compressor efficiency. The check valve aspect of this design is also unique, as it limits the maximum pressure behind the compressor impeller to prevent any overload of the turbocharger thrust bearing.

[0008] According to another aspect, the pressure relief channel is connected to the recess in the diffuser.

[0009] According to another aspect, the pressure relief channel includes a check valve. This check valve can be used to limit the maximum pressure that will be generated behind the impeller, thereby mitigating the risk of overload on the turbocharger thrust bearing.

[0010] According to another aspect, the turbine impeller is driven to the compressor impeller via a shaft.

[0011] According to another aspect, the compressor back plate is located in a recess in the diffuser and is opposite to the base plate of the compressor impeller.

[0012] The present invention also discloses the following technical solutions:

[0013] Option 1. A turbocharger comprising:

[0014] The compressor section includes a compressor housing and a compressor impeller located within the compressor housing, the compressor housing having an air inlet and a compressor air outlet;

[0015] A turbine section having a turbine housing and a turbine impeller located within the turbine housing, the turbine housing having an exhaust gas inlet and a turbine exhaust gas outlet, the turbine impeller being drivably connected to a compressor impeller, the exhaust gas inlet being configured to connect to an engine exhaust passage, and the turbine exhaust gas outlet being configured to connect to an exhaust system;

[0016] The compressor housing includes a diffuser having a recess for receiving the compressor impeller, the recess having a sidewall with an upper edge, and the compressor impeller having a base plate with an upper surface below the upper edge of the sidewall of the recess in the diffuser.

[0017] Option 2. The turbocharger according to Option 1, further comprising a pressure relief passage communicating with the recess in the diffuser.

[0018] Option 3. The turbocharger according to Option 2, wherein the pressure relief passage includes a check valve.

[0019] Option 4. The turbocharger according to Option 3, wherein the check valve includes a ball and spring check valve.

[0020] Option 5. The turbocharger according to Option 1, wherein the turbine impeller is shaft-driven to the compressor impeller.

[0021] Option 6. The turbocharger according to Option 1, further comprising a compressor backplate, the compressor backplate being located in the recess in the diffuser and opposite to the base plate of the compressor impeller.

[0022] Option 7. The turbocharger according to Option 6, further comprising a pressure relief passage in the compressor backplate.

[0023] Option 8. The turbocharger according to Option 7, wherein the pressure relief passage includes a check valve.

[0024] Option 9. The turbocharger according to Option 8, wherein the check valve comprises a ball and spring check valve.

[0025] Option 10. The turbocharger according to Option 7, wherein the pressure relief passage further extends through the diffuser.

[0026] Option 11. The turbocharger according to Option 6, further comprising a seal located between the compressor backplate and the diffuser.

[0027] Option 12. A turbocharger comprising:

[0028] The compressor section includes a compressor housing and a compressor impeller located within the compressor housing. The compressor housing has an air inlet and a compressor air outlet. The compressor housing includes a diffuser having a recess for receiving the compressor impeller. A compressor back plate is disposed in the recess of the diffuser and opposite to the base plate of the compressor impeller. The compressor back plate includes a pressure relief passage, which includes a check valve.

[0029] A turbine section having a turbine housing and a turbine impeller located within the turbine housing, the turbine housing having an exhaust gas inlet and a turbine exhaust gas outlet, the turbine impeller being drivably connected to a compressor impeller, the exhaust gas inlet being configured to connect to an engine exhaust passage, and the turbine exhaust gas outlet being configured to connect to an exhaust system;

[0030] The recess in the diffuser includes a sidewall with an upper edge, and the base plate of the compressor impeller has an upper surface below the upper edge of the sidewall of the recess in the diffuser.

[0031] Option 13. The turbocharger according to Option 12, further comprising a pressure relief passage communicating with the recess in the diffuser.

[0032] Option 14. The turbocharger according to Option 13, wherein the pressure relief passage includes a check valve.

[0033] Option 15. The turbocharger according to Option 14, wherein the check valve comprises a ball and spring check valve.

[0034] Option 16. The turbocharger according to Option 12, further comprising a compressor backplate located in the recess in the diffuser and opposite to the base plate of the compressor impeller.

[0035] Option 17. The turbocharger according to Option 16, further comprising a pressure relief passage in the compressor backplate.

[0036] Option 18. The turbocharger according to Option 17, wherein the pressure relief passage includes a check valve.

[0037] Option 19. The turbocharger according to Option 18, wherein the check valve comprises a ball and spring check valve.

[0038] Option 20. The turbocharger according to Option 17, wherein the pressure relief passage further extends through the diffuser.

[0039] Further applicability of this disclosure will become apparent from the detailed description, claims, and drawings. The detailed description and specific examples are intended for illustrative purposes only and are not intended to limit the scope of this disclosure. Attached Figure Description

[0040] This disclosure will be more fully understood from the detailed description and the accompanying drawings, in which:

[0041] Figure 1 A cross-sectional view of a turbocharger based on the principles of this disclosure; and

[0042] Figure 2 yes Figure 1 The diagram shows a detailed cross-sectional view of the compressor section of the turbocharger.

[0043] In the accompanying drawings, reference numerals may be reused to identify similar and / or identical elements. Detailed Implementation

[0044] refer to Figure 1 The turbocharger 10 includes a compressor section 12 having a compressor housing 14 with an air inlet 16 and a compressor air outlet 18 configured to communicate with an engine inlet manifold. A compressor impeller 20 is housed within the compressor housing 14. A turbine section 24 includes a turbine housing 26 with an exhaust gas inlet 28 connected to an exhaust outlet of the engine exhaust manifold and a turbine exhaust gas outlet configured to connect to a vehicle exhaust system. A turbine impeller 34 is housed within the turbine housing 26 and is drivenly connected to the compressor impeller 20 via a turbocharger shaft 36. In operation, the exhaust gas inlet 28 of the turbine section 24 receives engine exhaust gas that drives the turbine impeller 34. The turbine impeller 34 drives the turbocharger shaft 36 and the compressor impeller 20, which compresses the inlet air, which is then delivered to the engine inlet manifold.

[0045] refer to Figure 2 The compressor housing 14 includes a diffuser 37 having a recess 38 for receiving a compressor impeller 20. The compressor impeller 20 is disposed against a compressor backplate 40. The compressor backplate 40 is disposed around an oil slinger 42, which is disposed against a thrust bearing 44. A turbocharger shaft 36 is connected to the compressor impeller 20 and the oil slinger 42 and is rotatably supported by a journal bearing 46. In the illustrated embodiment, lubricating oil is supplied through an oil passage 48, which lubricates the journal bearing 46 and the thrust bearing 44.

[0046] According to this disclosure, the recess 38 in the diffuser 37 includes an upper edge 50. For the purposes of the term "upper," it means that the compressor impeller 20 has an upper surface 20A recessed relative to the upper edge 50, and that the compressor impeller 20 has a tapered convex surface 20b received in a concave tapered recess of the compressor back plate 40. The compressor section 12 utilizes the boost pressure generated by the compressor impeller to increase the back pressure on the compressor side of the annular seal 51, thereby mitigating oil leakage.

[0047] A one-way check valve 52 and a pressure relief passage 54 are used to limit the maximum pressure that will be generated downstream of the compressor impeller 20, thereby mitigating the risk of overload on the turbocharger thrust bearing 44. The check valve 52 may include a ball 52a, a spring 52b, and a threaded retainer 52c. Alternatively, other types of check valves may be used, such as, but not limited to, reed valves and duckbill valves. An O-ring seal 56 seals the passage 54 between the compressor housing 14 and the diffuser 37.

[0048] It is precisely the concave surface 20a of the compressor impeller 20 and its interaction with the relatively high diffuser edge 50 that are optimized to maximize the pressure behind the compressor impeller 20 while minimizing the impact on compressor efficiency. The check valve 52 is also unique because it limits the maximum pressure behind the compressor impeller 20 to prevent any overload of the turbocharger thrust bearing.

[0049] When using the engine's compressor front throttle valve, the turbocharger of this disclosure reduces oil leakage via the turbocharger compressor ring seal. The unique geometry of the compressor backplate, combined with the recessed compressor impeller, achieves a more favorable pressure differential across the compressor seal, while the check valve limits the maximum pressure behind the impeller during higher turbocharger speed operation, thereby limiting the load requirements of the turbocharger thrust bearing.

[0050] Positioning the compressor impeller recessed within the compressor backplate makes it more likely that the airflow generated by the impeller will impact the edges of the compressor backplate. The sharp edges of the recess's unique geometry increase the effectiveness of this action, and the combination of these factors will redirect a portion of the pressurized air behind the impeller. This results in a more favorable pressure differential across the compressor ring seals compared to a standard design and helps reduce oil leakage into the engine. These features are passive, and at high compressor impeller speeds, a significant amount of air will be redirected behind the compressor impeller, thus increasing the pressure beyond what a standard turbocharger bearing would be designed for. In this situation, a check valve 52 connected to the volume behind the compressor impeller 20 will be activated by the high pressure differential (pressure-driven valve opening), allowing some pressure to be released before damaging the bearing 44.

[0051] The recessed compressor impeller design allows for a larger operating area for the compressor pre-throttle valve concept during purging. This wider operating range enables a larger purging volume, allowing for the use of a larger fuel tank in the vehicle. Limiting oil leakage and subsequent engine consumption also benefits the emissions aftertreatment system and reduces the likelihood of pre-ignition or exhaust pipe smoke. It also reduces overall engine fuel consumption.

[0052] The foregoing description is merely illustrative in nature and is in no way intended to limit this disclosure, its application, or use. The broad teachings of this disclosure can be implemented in various forms. Therefore, while this disclosure includes specific examples, its true scope should not be so limited, as other modifications will become apparent upon examination of the drawings, specification, and the following claims. It should be understood that one or more steps within the method may be performed in a different order (or simultaneously) without altering the principles of this disclosure. Furthermore, while each of the embodiments described above is described as having certain features, any one or more of those features described with respect to any embodiment of this disclosure can be implemented and / or combined with features of any other embodiment, even if such combination is not explicitly described. In other words, the described embodiments are not mutually exclusive, and the arrangement of one or more embodiments with each other remains within the scope of this disclosure.

[0053] Spatial and functional relationships between components (e.g., between modules, circuit elements, semiconductor layers, etc.) are described using various terms, including “connection,” “joint,” “link,” “adjacent,” “next to,” “on top of,” “above,” “below,” and “set.” Unless explicitly described as “direct,” when describing the relationship between the first and second components in the above disclosure, the relationship can be a direct relationship in which no other intervening components exist between the first and second components, or it can be an indirect relationship (spatially or functionally) between the first and second components. As used herein, at least one of the phrases A, B, and C should be interpreted using non-exclusive logic or signifying logic (A or B or C) and should not be interpreted as meaning “at least one of A, at least one of B, and at least one of C.”

Claims

1. A turbocharger comprising: The compressor section includes a compressor housing and a compressor impeller located within the compressor housing, the compressor housing having an air inlet and a compressor air outlet; A turbine section having a turbine housing and a turbine impeller within the turbine housing, the turbine housing having an exhaust gas inlet and a turbine exhaust gas outlet, the turbine impeller being drivably connected to a compressor impeller, the turbine impeller and the compressor impeller being rotatable about an axis of rotation, the exhaust gas inlet being configured to connect to an engine exhaust passage, and the turbine exhaust gas outlet being configured to connect to an exhaust system; The compressor housing includes a diffuser having a recess for receiving the compressor impeller, the recess having a sidewall with an upper edge, and the compressor impeller having a base plate with an upper surface located below the upper edge of the sidewall of the recess in the diffuser in an axial direction along the axis of rotation; A compressor back plate, the compressor back plate being located in the recess in the diffuser and opposite to the base plate of the compressor impeller; and The pressure relief channel in the compressor backplate, wherein the pressure relief channel further extends through the diffuser.

2. The turbocharger of claim 1, further comprising a pressure relief passage communicating with the recess in the diffuser.

3. The turbocharger according to claim 1, wherein, The pressure relief channel includes a check valve.

4. The turbocharger according to claim 3, wherein, The check valve includes a ball and spring check valve.

5. The turbocharger according to claim 1, wherein, The turbine impeller is driven to the compressor impeller via a shaft.

6. The turbocharger of claim 1, further comprising a seal located between the compressor backplate and the diffuser.

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