WO2013160632A1

WO2013160632A1 - Improvements in valves

Info

Publication number: WO2013160632A1
Application number: PCT/GB2012/050941
Authority: WO
Inventors: Paul Wilkinson
Original assignee: Perkins Engines Company Limited
Priority date: 2012-04-27
Filing date: 2012-04-27
Publication date: 2013-10-31

Abstract

The present disclosure relates to improvements in valves and in particular to valves suitable for use as exhaust gas recirculation valves. The valve is for location in a sleeve (29), and comprises a housing (28) having a first end and a second end and defining an inlet and an outlet. The housing is configured at least partially to locate in the sleeve. The valve further comprises a valve member at least partially disposed within the housing (28), said valve member being moveable between open and closed positions. At least a section of the length of an external surface of the housing (28) is provided with a plurality of stepped portions such that the housing tapers inwardly in the direction of the second end.

Description

IMPROVEMENTS IN VALVES

Field

The present disclosure relates to improvements in valves and in particular to valves suitable for use as exhaust gas recirculation valves .

Background

Exhaust gas recirculation (EGR) is a known technique for use in internal combustion engines (petrol or diesel) wherein a portion of an engine's exhaust gas is recirculated back to the engine cylinders. EGR may be used to reduce emissions of oxides of nitrogen including NO and N0₂.

A typical EGR system may include a conduit, or other structure, fluidly connecting a portion of the exhaust path of an engine with a portion of the combustion gas/air intake system of the engine, thereby forming an EGR path. The mixing of the combustion gas with the exhaust gas typically takes place in an EGR mixer module. Different amounts of exhaust gas recirculation may be desirable under different engine operating conditions and in order to regulate the amount of exhaust gas recirculation, such systems typically employ an EGR valve that is disposed at some point in the EGR path.

The EGR valve may be located either upstream ('hot-side valve') or downstream ('cold side valve') of an EGR cooler which is located in the EGR path to cool the exhaust gas before it is mixed with the charge air. In addition, the EGR gas take off point may run from before the turbine to post turbocharger compressor (high pressure loop EGR) or from after the turbine to before the turbocharger compressor (low pressure loop EGR) .

EGR valves typically include a metal tubular housing, which locates in a metal sleeve or other cylindrical

opening, which may be located in the EGR mixer module, or a conduit in the EGR path or elsewhere in the engine . It has been found that it can be difficult to remove EGR valves from the casing in which it is mounted. Both the EGR valves and the casings are commonly made from aluminium and the clearances between them are very small as a good seal is required between the valve and the casing to minimise internal leakage through the valve . When two aluminium surfaces are in close contact, a process known as galling can occur, which can lead to high levels of friction.

Consequently it is very easy for the EGR valve to seize when it is being removed. If galling occurs during valve removal, a greater force is required to remove the valve, which means that the friction increases as does the risk of the

component seizing. It should be noted that galling is not restricted to aluminium components, but can occur on any similar metallic surfaces, e.g. stainless steel to stainless steel. The problem is more evident in aluminium due to its softness. Steel is harder and more difficult to gall, so the problem is less likely to occur; nonetheless it is possible.

It is therefore an object of the present disclosure to provide a solution to the aforementioned problems without compromising the sealing ability of the two mating surfaces.

Summary Of The Invention

The present disclosure therefore provides a valve for location in a sleeve, said valve comprising: a housing having a first end and a second end and defining an inlet and an outlet, said housing being configured at least partially to locate in the sleeve,- and

a valve member at least partially disposed within the housing, said valve member being moveable between open and closed positions;

wherein at least a section of the length of an external surface of the housing is provided with a plurality of stepped portions such that the housing tapers inwardly in the direction of the second end.

The disclosure further provides a valve assembly comprising the aforesaid valve and a sleeve adapted to receive the second end of the valve housing.

The disclosure further provides an exhaust gas

recirculation system comprising the aforesaid valve assembly and an exhaust gas recirculation mixer module.

The disclosure further provides an engine comprising the aforesaid exhaust gas recirculation system.

Brief Description of the Drawings

Figure 1 is diagrammatic representation of an engine with an exhaust gas recirculation system

Figure 2 is an isometric view of an exhaust gas recirculation valve of the exhaust gas recirculation system of Figure 1;

Figure 3 is side elevation of the exhaust gas valve of Figure 2 ;

Figure 4 is a cross sectional end elevation of the exhaust gas valve on the line A-A of Figure 3; Figure 5 is a cross-sectional side elevation of a section of Figure 2 showing the exhaust gas recirculation valve mounted in a tubular sleeve of the exhaust gas

recirculation mixer module; and

Figure 6 is an enlarged section showing the stepped portion of the external surface of the housing of the exhaust gas recirculation valve and a corresponding portion of an internal surface of the tubular sleeve of Figure 5. Detailed Description

Referring to Figure 1, there is shown an exemplary engine 10 having a high pressure loop exhaust gas

recirculation (EGR) system 11 with a hot side EGR valve 23. The engine 10 may be any kind of suitable engine, such as an internal combustion engine and in particular a diesel fuelled compression- ignition (CI) internal combustion engine. The internal combustion engine 10 may include a plurality of combustion cylinders housed in a crankcase. Each combustion cylinder may be fluidly coupled with an intake manifold 12 and with an exhaust manifold 13. While single intake and exhaust manifolds 12, 13 are shown, it should be understood that more than one intake or exhaust manifolds 12, 13 may be used, with each intake or exhaust manifold 12, 13 coupled to a plurality of combustion

cylinders. A fuel, such as diesel fuel, or fuel air mixture may be introduced into each combustion cylinder 12 and combusted therein, in a known manner. The engine 11 may further comprise a turbocharger 14. The turbocharger 14 may include a turbine 15 and a compressor 16 having a turbine wheel and a compressor wheel (not shown) respectively, both mounted on a common shaft 17. The compressor 16 may receive charge from a source such as ambient air, and may supply compressed charge air or other gas to the intake manifold 12 of the engine 10 via a charge air conduit 18. The compressed gas may be passed through a charge air cooler 19 before it passes into the intake manifold 12.

The turbine 15 may be fluidly connected with the exhaust manifold 13, by means of an exhaust conduit 20, and to an exhaust system (not shown) of engine 10, by means of a further conduit 21. The exhaust system may include an after treatment device which removes combustion products from the exhaust gas stream and one or more mufflers to dampen engine noise, before the exhaust gas is discharged to an ambient environment. The emission of the engine 12 is commonly referred to as exhaust gas but may in reality be a mixture of gas, other fluids such as liquids, and even solids, comprising for example C0₂, H₂0, NOx and particulate matter.

Although not shown in Figure 1, the turbocharger 14 may be regarded as being a turbocharging arrangement comprising multiple turbochargers 14 in, for example, a series

configuration.

The EGR system 11 may comprise an EGR conduit 22 which, in the case of a high pressure EGR system with a hot side EGR valve, fluidly connects the exhaust conduit 20 and the inlet manifold 12, so that at least a portion of the exhaust gas may be recirculated from the exhaust conduit 20 to the intake manifold 12. This portion of recirculated exhaust gas will be referred to herein as "EGR gas". The EGR system 11 may further comprise an EGR valve 23, which may be configured to be controlled by a controller 24 so as to vary the quantity of EGR gas flowing through the EGR conduit 22. The EGR gas may also be passed through an EGR cooler 26 to cool the EGR gas before being directed to the intake

manifold 12. The order of the EGR cooler 26 and the EGR valve 23 may be reversed to give a cold side EGR valve 23.

The controller 24 may be a single controller or

comprise a plurality of independent or linked control units. The controller 24 may be configured to receive and process signals from various sensor arrangement and may be further configured to determine the operating conditions of the engine 10 and or the EGR system 11.

An EGR mixer module 27 may be configured to mix the intake air from the charge air conduit 18 together with the EGR gas from EGR conduit 22 to create a mixture having a desirable level of homogeneity. In some embodiments the EGR mixer module 27 may simply be a conduit and/or the intake manifold 12, which may be provided with features such as for example vanes, valves, or labyrinths to increase the mixing characteristics if desired. In some embodiments the EGR mixer module 27 may include a dedicated fluid mixer

assembly.

The EGR valve 23 may be any type of valve configured to open or close off EGR conduit 22, such that the position of EGR valve 23 (valve position) determines the flow rate through EGR conduit 22 (EGR flow rate) . EGR valve 23 may include a flapper valve (e.g. a throttle-type butterfly valve) or any other suitable type of valve. In some

embodiments, EGR valve 23 may be operated via servo control or any suitable actuation mechanism. In some embodiments, EGR valve 23 may be controllable to allow varying EGR flow rates and/or selectively completely block EGR gas flow.

Alternatively it may be a two position on/off system.

Referring now to Figures 2 to 5, the EGR valve 23 has a generally cylindrical housing 28, which houses the valve stem 34. The housing 28 may be made from aluminium or another suitable material. The housing 28 defines a valve inlet port 30 and a valve outlet port 31 for the ingress of EGR gas from the EGR conduit and the egress of EGR gas into the EGR mixer module 27. The EGR valve housing 28 is at least partially inserted into the bore of a tubular sleeve 29 which may be a part of the EGR mixer module 27.

Alternatively (not shown) it may be located in the bore of a similar tubular sleeve located in the EGR conduit 22 or in another part of the engine 10. Typical clearances between the external surface of the EGR valve housing 28 and the internal surface of the tubular sleeve 29 are between 9 microns for the tightest fit and 64 microns for the loosest fit. A close fit between the surfaces is required to

minimise internal leakage through the EGR valve 23.

It is preferable to minimise the area of contact between the external surface of the EGR valve housing 28 and the internal surface of the tubular sleeve 29, without compromising the sealing width between the valve inlet and outlet ports 30,31. To achieve this the respective surfaces are provided with sealing portions which provide a stepped surface (see Figures 5 and 6) . The EGR valve housing 28 therefore has a cross section which becomes smaller towards its free end, which is the end which is located innermost in the tubular sleeve 29. In one arrangement the EGR valve housing 28 is generally cylindrical and the sealing portions comprise rings around the surfaces and there may be three such rings. The resulting steps 32,33 may be sized and arranged in such a fashion that the length of the section of the external surface of the EGR valve housing 28 that is in sealing contact with the internal surface of the tubular sleeve 29 (hereinafter referred to as "the contact length") may be less than or equal to the physical distance between the valve inlet and outlet ports 30,31. The width of the sealing rings may be between 5mm and 13mm and the depth may by approximately 0.5mm (i.e. they may stand proud of the main diameter by approximately 0.5mm) .

Industrial Applicability

The present disclosure is applicable to EGR valves used on engines such as internal combustion engines . The engines may be of any size, including 4 cylinder and 6 cylinder engines .

During operation of the engine 10, a fuel, such as diesel fuel, may be injected into the combustion cylinders and combusted. Exhaust gas produced as a result of the combustion process may be directed from the combustion cylinders to the exhaust manifold 13. At least a portion of the exhaust gas within the exhaust manifold 13 may be directed to flow through and drive the turbine 15. The spent exhaust gas may be discharged from turbine 15 to atmosphere, via the exhaust system, before which it may be treated to reduce emissions. Another part of the exhaust gas, namely the EGR gas, may be directed to the EGR mixer module 27. As stated previously the EGR gas may be cooled before passing into the EGR mixer module 27.

The turbine 15 may transmit power to the compressor 16 via turbocharger shaft 17 on which they may both be mounted. The compressor 16 draws in charge air and compresses it. The compressed charge air is discharged from the compressor 18 and passes along the charge air conduit 20 to the intake manifold 12 via the charge air conduit 18 and, where

included, the EGR mixer module 27. As stated previously, the compressed charge air may be cooled before passing into the EGR mixer module 27/intake manifold 12.

When the EGR valve 23 is in a closed position, no EGR gas flows along the EGR conduit 22 and the compressed charge air passes to the intake manifold 12 for combustion, which may be via the EGR mixer module 27.

When the EGR valve 23 is in an open position, EGR gas flows along the EGR conduit 22 and, where included in the EGR system 11, into the EGR mixer module 27, and is mixed with the clean compressed combustion gas. The mixture is then directed to the intake manifold 12 for combustion. The EGR valve 23 may be removed for maintenance by extracting it from the tubular sleeve 29. As a result of the stepped profile of the external surface of the EGR valve housing 28 and the internal surface of the tubular sleeve 29, once it has been extracted by a short distance (which is equal to the contact length) the steps 32,33 on the

respective surfaces are disengaged and there is a much greater degree of clearance between the EGR valve housing 28 from the tubular sleeve 29, allowing the EGR valve 23 to be removed with ease .

Claims

CLAIMS :

1. A valve for location in a sleeve, said valve

comprising:

a housing having a first end and a second end and defining an inlet and an outlet, said housing being configured at least partially to locate in the sleeve; and

2. A valve as claimed in claim 1 in which the surface of the housing has three stepped portions.

3. A valve as claimed in any one of the preceding claims in which the stepped portions extend circumferentially around the housing surface. . A valve as claimed in any one of the preceding claims in which the valve is an exhaust gas recirculation valve.

5. A valve assembly comprising a valve as claimed in any one of the preceding claims and a sleeve adapted to receive the second end of the valve housing.

6. A valve assembly as claimed in claim 5 in which an internal surface of the sleeve is provided with stepped - 11 - portions which are complementary to the stepped portions of the valve housing.

7. A valve assembly as claimed in claim 5 or claim 6 in which the stepped portions are sized and arranged such that the length of sealing contact between the external surface of the chousing and the internal surface of the sleeve is less than or equal to the distance between the inlet and the outlet .

8. A valve assembly as claimed in claim 8 in which the sleeve forms a part of an exhaust gas recirculation mixer module . 9. A valve assembly as claimed in any one of claims 5 to 8 in which the housing and the sleeve are formed from the same metallic material.

10. An exhaust gas recirculation system comprising a valve assembly as claimed in any one of the claims 5 to 9 and an exhaust gas recirculation mixer module.

11. An engine comprising the exhaust gas recirculation system of claim 10.