GB2543049A

GB2543049A - Exhaust Gas Recirculation Valve

Info

Publication number: GB2543049A
Application number: GB1517543.3A
Authority: GB
Inventors: Haigh Edward
Original assignee: Perkins Engines Co Ltd
Current assignee: Perkins Engines Co Ltd
Priority date: 2015-10-05
Filing date: 2015-10-05
Publication date: 2017-04-12
Also published as: CN106560613A; GB201517543D0

Abstract

Disclosed is a valve arrangement for use in an exhaust gas recirculation system in an internal combustion engine arrangement. The valve arrangement 10 includes a housing 30 having a passage 104 for exhaust gas, part of which defines an opening 36 for the valve member 20. The valve arrangement further includes a valve shaft 24 received in the valve opening, the valve shaft being driven by an actuator 50 to move the valve and hence open and close the valve. A pressure chamber 80 is provided in fluid communication with the passage via the valve opening. The pressure in the pressure chamber is adjustable to a pressure equal to or greater than a pressure in the passage. Pressurised air from the pressure chamber is used to blow any exhaust gas/soot particles away from the valve shaft, thereby preventing clogging of the passage and jamming of the EGR valve.

Description

EXHAUST GAS RECIRCULATION VALVE

Technical Field [0001] The present disclosure relates to an exhaust gas recirculation system for an internal combustion engine. In particular, present disclosure relates to a sealing arrangement for an exhaust gas recirculation valve.

Background [0002] Internal combustion engines produce a complex mixture of air pollutants. These air pollutants may be composed of solid particulate matters and gaseous compounds including nitrous oxides (NOx). Use of exhaust gas recirculation (EGR) systems for reducing the amount of NOx produced during the operation of internal combustion engine is known in the art. An EGR system requires a valve assembly that selectively allows the flow of the exhaust gases from the exhaust manifold to the intake manifold for mixing the exhaust gases with the intake air supply to be fed into the combustion chamber.

[0003] Typically, the flow of exhaust gas back into the combustion chamber of the engine is regulated by an EGR valve. The EGR valve generally includes a valve head at the end of the valve shaft disposed within an EGR passageway and movable between open and closed positions to selectively pass or restrict the flow of exhaust gases to the intake of the engine. The EGR valve housing generally is located such that the valve head of the valve is disposed in the EGR passageway and the valve actuation mechanism generally is placed outside the passageway. The valve actuation mechanism is coupled to the actuator end of the valve shaft. The valve shaft, may be extending through a valve opening defined in the valve housing. The valve opening at one end is proximate to the actuator end and the other end of the valve opening is exposed to the exhaust passageway. The valve actuation mechanism actuates the valve in order to move the valve between an open and closed position. Generally, the space between the valve shaft and the wall of the valve opening is occupied by a bushing or other sealing arrangement. However, due to movement of the valve shaft in the valve opening, an unintended clearance may occur in the valve opening. Due to very high pressure in the EGR passageway in comparison to the pressure around the actuator end of the valve, the exhaust gases or particulate matters from the EGR passageway may escape through the valve opening towards the actuator end.

[0004] The exhaust gases and the particulate matters in the exhaust gases may enter the valve opening and deposit on the valve shaft or the wall of the valve opening. Also, the exhaust gases and the particulate matter in the exhaust gases may leak through the valve opening and contaminate and deposit on the parts, for example a valve actuation system, disposed on the other side of the valve opening. Further, the presence of the condensate or soot in the valve opening or on the valve shaft may hamper the actuation of the valve by restricting free movement of the valve shaft in the valve opening. The soot particles may also lead to abrasion of the valve shaft or the wall of the valve opening that may lead to part failure.

[0005] Therefore, it is desirable that the exhaust gases from the exhaust manifold be prevented from entering the valve opening that receives the valve shaft. US Patent No. 8,967,125 discloses providing a lip seal placed between the valve housing and the valve shaft to prevent the leakage of the exhaust gases towards the valve actuator. For preventing failure of the lip seal, US Patent No. 8,967,125 further discloses placing a deposit-guard plug placed between the valve housing the valve shaft and adjacent to the lip seal. Further, US Patent No. 6,997,169 discloses providing a flexible seal member between the valve shaft and the casing to prevent exhaust gases from leaking towards the valve drive unit. However, such sealing members may be exposed to the exhaust gases and soot particles which may damage the sealing member, for example by abrasion. Further, the sealing members placed in the valve opening in sliding contact with the valve shaft may increase the resistive forces such as frictional forces that hamper the free movement of the valve shaft within the valve opening. Also, the sealing members disposed between the valve shaft and the valve opening may be subject to very high working forces and temperatures leading to failure of the sealing member. Thus, such sealing arrangements may be subject to frequent repair or replacement.

Summary of the Invention [0006] Present disclosure provides for a valve comprising a housing having a passage for exhaust gas and defining a valve opening and a valve shaft received in the valve opening and driven by an actuator to open and close the valve. The valve further comprises a pressure chamber in fluid communication with the passage via the valve opening. The pressure of the pressure chamber adjustable to a pressure equal to or greater than a pressure of the passage.

[0007] Present disclosure further provides for an engine comprising an EGR valve. The engine comprises a housing having a passage for exhaust gas and defining an EGR valve opening. A valve shaft is received in the EGR valve opening and the valve shaft is driven by an actuator to open and close the valve. Further, a pressure chamber is provided in fluid communication with the passage via the valve opening. The the pressure of the pressure chamber adjustable to a pressure equal to or greater than a pressure of the passage.

[0008] A method of operating an EGR valve is disclosed. The EGR valve comprises a housing having a passage for exhaust gas and defining an EGR valve opening. A valve shaft is received in the EGR valve opening and driven by an actuator to open and close a valve element. Further, a pressure chamber is provided in fluid communication with the passage via the valve opening. The method of operating such valve comprises pressurizing the pressure chamber and maintaining a pressure in the pressure chamber equal to or greater than a pressure of the passage.

Brief Description of the Drawings [0009] FIG. 1 illustrates a schematic diagram of an engine having an EGR valve.

[0010] FIG. 2 illustrates a schematic diagram of an EGR valve in accordance with an embodiment of the present disclosure.

Detailed Description [0011] FIG. 1 illustrates an engine 100 with a valve 10. The engine 100 may be any internal combustion engine. The engine 100 has an intake passage 102 and an exhaust passage 104. An EGR passageway 32 fluidly connects the exhaust passage 104 to the intake passage 102 of the engine 100. A valve 10 is disposed in the EGR passageway 32 to regulate the flow of exhaust gases from the exhaust passage 104 towards the intake passage 102. The valve 10 works as an EGR valve for the engine 100. In the illustrated embodiment, valve 10 is disposed in the EGR passageway 32 proximate to the exhaust passage 104. In an alternate embodiment, the valve 10 may be placed anywhere in the EGR passageway 32 or on the exhaust passage 104 to allow the valve 10 to regulate the flow of exhaust gases in the EGR passageway 32.

[0012] FIG. 2 illustrates the valve 10 with a valve member 20. As illustrated, the valve member 20 has a valve head 22, a valve shaft 24 and an actuator end 26. The valve 10 further has a valve housing 30. The valve shaft 24 is configured to move reciprocally in a valve opening 36 defined by the valve housing 30. The valve opening 36 may be an elongated cavity. The valve opening 36 may have a first end 38 proximate to the actuator end 26 of the valve member 20, and a second end 40 exposed to the EGR passageway 32. The valve housing 30 may partly define a portion of the EGR passageway 32.

[0013] A valve actuation system 50 may be coupled to the valve member 20 near the actuator end 26 to impart a reciprocating motion in the valve member 20 to open and close the valve 10. The valve actuation system 50 may be any mechanism known in the art, for example a mechanical actuation system such as a cam operated valve actuation mechanism or an electronic actuation system such as a controller operated solenoid actuation mechanism, etc. can be used as an actuator for the valve 10.

[0014] The valve 10 may further have an actuation chamber 60 that encloses or covers the valve actuation system 50 and other parts of the valve 10. The actuation chamber 60 protects the parts of the valve actuation system 50 and valve 10 from dust or other contaminants that may deposit on the parts of the valve 10 or engine 100. A bushing 70 may be placed between the valve housing 30 and the valve shaft 24 in the valve opening 36. The bushing 70 may provide a bearing or a guiding surface for the valve shaft 24. The bushing 70 may be lubricated for reducing friction between the valve shaft 24 and the bushing 70. In an alternate embodiment, the wall of the valve opening 36 may provide a bearing or guiding surface for the valve shaft 24.

[0015] Further, the EGR passageway 32 defines a valve seat 34. The valve head 22 is received in the valve seat 34 to block the EGR passageway 32. When the valve head 22 moves away from the valve seat 34, the passageway 32 is unblocked for allowing passage of exhaust gases. The valve actuation system 50 moves the valve member 20 reciprocally along the axis of the valve shaft 24 to open or close the valve 10. In the illustrated embodiment, a poppet type valve is shown. In an alternate embodiment, any other valve suitable for the EGR system, for example a butterfly valve, may be used. Any suitable actuation system 50 may be used in accordance with the type of valve used. For example, for a butterfly valve, an actuation system that can impart a rotary motion to a valve member may be used.

[0016] As illustrated in FIG. 2, a pressure chamber 80 may be provided on the valve housing 30 proximate to the first end 38 of the valve opening 36 and in fluid communication with the EGR passageway 32 via valve opening 36. The pressure chamber 80 may be defined by a pressure chamber wall 82. The pressure chamber wall 82 may be formed integrally with the valve housing 30. In an alternate embodiment, the pressure chamber wall 82 may be a separate component attached to the valve housing 30. The pressure chamber 80 is configured to hold a pressurized gas in the pressure chamber 80. The pressurized gas may be air or any other gas suitable for the purpose.

[0017] The valve shaft 24 passes through the pressure chamber 80. A shaft seal 84 is positioned between the valve shaft 24 and the pressure chamber wall 82 to prevent leakage of air from the pressure chamber 80 towards the valve actuation system 50. In the embodiment as illustrated, the pressure chamber 80 is defined by a rigid wall 82 and is shown rectangular in shape. In an alternate embodiment, the pressure chamber wall 82 may be composed of any flexible material that may be capable of holding a pressurized gas, and the pressure chamber 80 may be of any suitable shape.

[0018] A source of pressurized air 90, for example an air pump, may be coupled or connected to the pressure chamber 80 using a conduit 92 to pressurize the pressure chamber 80. In accordance with an embodiment, a turbocharger system with or without an air charge cooler may be used as a source of pressurized air. In accordance with another embodiment, any source of pressurized air that may be available on a machine may be used for pressurizing the pressure chamber 80.

[0019] Further, a non-return valve 94 may be provided in the conduit 92 to prevent any reverse flow of the air towards the source of pressurized air 90. The non-return valve 94 may be any known non-retum valve in the art.

[0020] During operation of the EGR valve 10, a valve shaft to bushing clearance 37 in valve opening 36 between the bushing 70 and the valve shaft 24 may provide for a passage for the exhaust gas and soot particles to pass through the valve shaft to bushing clearance 37 towards the valve actuation system 50. The ingress of exhaust gas and particles into valve shaft to bushing clearance 37 may result in deposits forming on the valve shaft 24 or the bushing 70 that may reduce the valve shaft to bushing clearance 37 to such an extent that the valve shaft 24 may no longer be able to move uninhibited relative to bushing 70. This may result in damage to the valve mechanism or may also result in valve actuation failure.

[0021] To prevent any such passage of the exhaust gases and the soot particles through the valve shaft to bushing clearance 37, during operation of the EGR Valve 10, pressure in the pressure chamber 80 may be controlled or adjusted in order to keep the pressure in the pressure chamber 80 equal to or greater than the pressure in the EGR passageway 32. This way during operation of the EGR valve 10, the pressure at the first end 38 of the valve opening 36 is equal to or higher compared to the pressure at the second end 40 of the valve opening 36. By keeping the pressure in the pressure chamber 80 at a higher level compared to the pressure in the EGR passageway 32, the exhaust gases or any soot particles are prevented from entering the valve stem to bushing clearance 37. Upon occurrence of the valve shaft to bushing clearance 37 in the valve opening 36 along the valve shaft 24, the pressurized air contained in the pressure chamber 80 escapes through the valve opening 36 towards the EGR passageway 32. However, any flow of exhaust gas or particulate matters in the exhaust gas is prevented due to the pressure gradient along the valve opening 36.

[0022] After escaping the pressure chamber 80, the pressurized air that enters the EGR passageway 32 may get mixed with the exhaust gas and flow along with the exhaust gases towards the intake manifold. The amount of the pressurized air that escapes from the pressure chamber 80 through the valve opening 36 may be very small to an extent that it has negligible effect on the overall working of the engine 100.

[0023] In accordance with an embodiment, the EGR Valve assembly may also include pressure sensors 86 in the EGR passageway 32 and the pressure chamber 80. Further, a controller may be coupled to the pressure sensors 86 and the air pump to control or adjust the pressure inside the pressure chamber 80, in order to maintain the pressure in the pressure chamber 80 at an equal to or higher than pressure in the EGR passageway 32. In accordance with an embodiment, a valve may be used in the conduit that controls the flow of air or gas in the pressure chamber 80. Such valve may be coupled to the controller in order to control the pressure inside the pressure chamber to a lever equal to or higher than the pressure in the exhaust gas passageway 104 or the EGR passageway 32.

Industrial Applicability [0024] According to present disclosure, a contactless sealing arrangement can be provided for sealing the valve opening 36. The sealing of the valve opening 36 is achieved by a pressure gradient at the two distant ends of the valve opening 36. The pressure gradient is created by keeping the pressure in the pressure chamber 80 higher than the pressure in the EGR passageway 32.

[0025] The EGR valve 10 in accordance with the present disclosure provides for a contactless sealing arrangement for sealing the valve opening 36 that receives the valve shaft 24. The valve 10 in accordance with the present disclosure provides for an effective way to prevent the exhaust gas and soot particles from entering the valve opening 36.

[0026] In an embodiment, an EGR valve 10 may comprise a housing that at least partly defines a passage for exhaust gases. The housing may define an EGR valve opening 36 that receives a valve shaft 24. The valve shaft 24 may be driven by an actuator to open or close the valve 10. A pressure chamber 80 is provided in fluid communication with the exhaust gas passage. The pressure chamber 80 establishes fluid communication with the EGR passageway 32 via the EGR valve opening 36. Present disclosure provides for a method to provide for a contactless seal for such EGR Valve 10. The method includes pressurizing the pressure chamber 80 with a gas or air. Further, the method includes keeping the pressure in the pressure chamber 80 at a level equal to or greater than the pressure in the exhaust gas passage.

[0027] In an embodiment, the pressure chamber 80 may be connected to a source of pressurized or compressed air using a conduit 92. In another embodiment, there may be a non-retum valve 94 may be placed in the conduit 92 that connects that pressure chamber 80 with the source of pressurized air. The non-return valve 94 allows flow of pressurized air from the source of pressurized air towards the pressure chamber 80, while it prevents any reverse flow of air from the pressure chamber 80 towards the source of pressurized air. In another embodiment, the source of pressurized air may be a turbocharger system of an engine. In an alternate embodiment, compressed air from a charge air cooler may be used as a source of pressurized air.

[0028] Using the EGR valve 10 or the method of operating the EGR valve 10 according to the present disclosure, a contactless seal may be provided for the valve opening 36. Such sealing arrangement prevents any flow of exhaust gases or soot particles through the valve shaft to bushing clearance 37. This way the valve opening 36 and the actuation chamber 60 of the engine 100 may be protected from unwanted exhaust gases and soot particles that may enter and clog the valve shaft to bushing clearance 37 by and the parts of the engine 100 that are placed in the actuation chamber 60.

Claims

Claims What is claimed is:

1. A valve comprising: a housing having a passage for exhaust gas and defining a valve opening; a valve shaft received in the valve opening and driven by an actuator to open and close the valve, and a pressure chamber in fluid communication with the passage via the valve opening, the pressure of the pressure chamber adjustable to a pressure equal to or greater than a pressure of the passage.

2. A valve as claimed in claim 1, further comprising a shaft seal placed between the pressure chamber and the valve shaft.

3. A valve as claimed in claim 1, wherein the pressure chamber is integrally formed with the housing.

4. A valve as claimed in claim 1, wherein the pressure chamber is pressurized by a source of compressed air.

5. A valve as claimed in claim 1, wherein the pressure chamber is pressurized by a source of compressed air through a non-return valve.

6. A valve as claimed in claim 1, wherein the pressure chamber is pressurized by compressed air from a turbocharger system of an engine.

7. A valve as claimed in claim 6, wherein compressed air from the turbocharger after a charge air cooler is used to pressurize the pressure chamber.

8. A valve as claimed in claim 1, further comprising an actuation chamber enclosing the pressure chamber and the valve shaft.

9. An engine comprising: an EGR valve; a housing having a passage for exhaust gas and defining an EGR valve opening; a valve shaft received in the EGR valve opening and driven by an actuator to open and close the valve; a pressure chamber in fluid communication with the passage via the valve opening, the pressure of the pressure chamber adjustable to a pressure equal to or greater than a pressure of the passage.

10. An engine as claimed in claim 9, further comprising a shaft seal placed between the pressure chamber and the valve shaft.

11. An engine as claimed in claim 9, wherein the pressure chamber is integrally formed with the housing.

12. An engine as claimed in claim 9, wherein the pressure chamber is pressurized by a source of compressed air.

13. An engine as claimed in claim 9, wherein the pressure chamber is pressurized by a source of compressed air through a non-return valve.

14. An engine as claimed in claim 9, wherein the pressure chamber is pressurized by compressed air from a turbocharger system of the engine.

15. An engine as claimed in claim 14, wherein compressed air from the turbocharger after a charge air cooler is used to pressurize the pressure chamber.

16. An engine as claimed in claim 9, further comprising an actuation chamber enclosing the pressure chamber and the valve shaft.

17. A method of operating an EGR valve, the EGR valve comprising a housing having a passage for exhaust gas and defining an EGR valve opening; a valve shaft received in the EGR valve opening and driven by an actuator to open and close a valve element; and a pressure chamber in fluid communication with the passage via the valve opening, the method comprising: pressurizing the pressure chamber; and maintaining a pressure in the pressure chamber equal to or greater than a pressure of the passage.

18. A method as claimed in claim 17, wherein the pressure in the pressure chamber is maintained by connecting the pressure chamber to a source of compressed air.

19. A method as claimed in claim 17, wherein the pressure in the pressure chamber is maintained by connecting the pressure chamber to a source of compressed air through a non return valve.

20. A method as claimed in claim 17, wherein the pressure in the pressure chamber is maintained by connecting the pressure chamber to a turbocharger system of an engine.