CLIAMS:We Claim:
1. An exhaust gas recirculation valve (10) comprising an inlet (12), an outlet (14) and a valve element (16), one end of said valve element (16) allowing fluid communication between said inlet (12) and said outlet (14) in dependence of movement of said valve element (16),
characterized in that
- a diaphragm (18);
- a valve guide (20); and
- a spring (22) ;
said diaphragm (18) connected to a second end of said valve element (16), said diaphragm (18) forming a chamber (24) within said exhaust gas recirculation valve (10) being isolated from the part of the exhaust gas recirculation valve (10) accommodating said valve element (16) said chamber (24) adapted to be filled with pressurized gas;
said valve guide (20) spaced apart from said diaphragm (18), said valve guide (20) located in proximity of said inlet (12) of said exhaust gas recirculation valve (10); and
said spring (22) located in space between said diaphragm (18) and said valve guide (20).

2. The exhaust gas recirculation valve (10) as claimed in claim 1, wherein said valve element (16) is a normally open valve element.

3. The exhaust gas recirculation valve (10) as claimed in claim 1, wherein said valve element (16) is a spring loaded normally open valve element.

4. The exhaust gas recirculation valve (10) as claimed in claim 1, wherein said chamber (24) is isolated from part of the exhaust gas recirculation valve (10) accommodating said valve element (16) in a manner such that no fluid communication exists between the chamber (24) and any other part of the exhaust gas recirculation valve (10).

5. An exhaust gas recirculation system (26) comprising an exhaust gas path (28), an intake manifold (30) and a exhaust gas recirculation valve (10) adapted to allow fluid communication between said exhaust gas path (28) and said intake manifold (30);
Characterized in that
said exhaust gas recirculation valve (10) comprising a diaphragm (18) connected to a second end of a valve element (16), said diaphragm (18) forming a chamber (24) within said exhaust gas recirculation valve (10) and being isolated from the part of the exhaust gas recirculation valve (10) accommodating said valve element (16) said chamber (24) adapted to be filled with pressurized gas; and
at least a part of said chamber (24) fitted into the exhaust gas path (28) to enable heat transfer from said exhaust pas path (28) to said chamber (24). ,TagSPECI:Field of the invention
[001] This invention relates to an exhaust gas recirculation valve.
[002] This invention relates to an exhaust gas recirculation system.

Background of the invention
[003] The use of exhaust gas recirculation system and an exhaust gas recirculation valve is already known in the state of the art. US patent number 5255659 discloses one such exhaust gas system comprising an exhaust gas recirculation valve. The exhaust gas recirculation valve comprising a first passage connected to the intake manifold and a second passage connected to the exhaust manifold. A valve element is position in between the first and second passage. A two sided diaphragm is located in the valve body with one side being operatively connected to the first passage and the second side being operatively connected to the second passage. There is also provided a means for controlling operating of the valve element.

Brief description of the accompanying drawings
[004] Different modes of the invention are disclosed in detail in the description and illustrated in the accompanying drawing:
[005] Figure 1 illustrates an exhaust gas recirculation valve in accordance with this disclosure; and
[006] Figure 2 illustrates an exhaust gas recirculation valve in accordance with this disclosure used in a exhaust gas recirculation system.

Detailed description of the invention
[007] Figure 1 illustrates an exhaust gas recirculation valve in accordance with this disclosure used in a exhaust gas recirculation system. The exhaust gas recirculation valve 10 comprises an inlet 12, an outlet 14 and a valve element 16. In dependence of the movement of the valve one end of the valve element 16 allows fluid communication between inlet 12 and the outlet 14. The exhaust gas recirculation valve 10 is characterized by comprising a diaphragm 18, a valve guide 20 and a spring 22. The diaphragm 18 is connected to a second end of the valve element 16. The diaphragm 18 forms a chamber 24 within the exhaust gas recirculation valve 10 and is isolated from the part of the exhaust gas recirculation valve 10 accommodating the valve element 16. The chamber 20 is adapted to be filled with pressurized gas. The valve guide 20 is spaced apart from said diaphragm 18. The valve guide 20 is located in proximity of the inlet 12 of said exhaust gas recirculation valve 10 and the spring (22) is located in the space between the diaphragm 18 and the valve guide (20).

[008] The valve element 16 of the exhaust gas recirculation valve is a normally open valve element. The valve element 16 is a spring loaded normally open valve element. The chamber 24 is isolated from part of the exhaust gas recirculation valve 10 accommodating the valve element 16 in a manner such that no fluid communication exists between the chamber 24 and any other part of the exhaust gas recirculation valve 10.

[009] As seen in figure 2, the exhaust gas recirculation system 26 comprises an exhaust gas path 28, an intake manifold 30 and an exhaust gas recirculation valve 10. The exhaust gas recirculation valve 10 is adapted to allow fluid communication between the exhaust gas path 28 and the intake manifold 30. The exhaust gas recirculation system is characterized by an exhaust gas recirculation valve 10 comprising a diaphragm 18 connected to a second end of a valve element 16. The diaphragm 18 forms a chamber 24 within the exhaust gas recirculation valve 10 and is isolated from the part of the exhaust gas recirculation valve 10 accommodating the valve element 16. The chamber is 24 is filled with pressurized gas. At least a part of the chamber 24 is fitted into the exhaust gas path 28 to enable heat transfer from the exhaust gas path 28 to the chamber 24.

[0010] The working of the exhaust gas recirculation valve 10 and the exhaust gas recirculation system 26 can be explained as follows. The specific application in question here is a generator set application. The generator set 32 as seen in figure 2 is a fuel based combustion engine which runs at a constant speed. The principle of working for the exhaust gas recirculation system 26 used in a generator is that generation of smoke and value of lambda has to be taken care depending on the load on the generator set. The principle of working for the exhaust gas recirculation system 26 used in a diesel engine is that tradeoff between NOx emissions and smoke emission has to be achieved by controlling the lambda [ ratio of actual air fuel ratio to stoichiometric air fuel ratio] at all the loads. At the lower loads to the engine and the exhaust gas temperature in exhaust gas path 28 will be low. Also the heat transfer between exhaust gas path 28 and exhaust gas recirculation valve chamber 24 will be low. As a result of this, gas expansion inside the chamber is low and the diaphragm 18 will be moving upwards because of the spring 20 force leading to increase in valve opening realizing more exhaust gas recirculation leading to highest NOx emission reduction without much increase in smoke emission from the engine.

[0011] However at the engine full load, fuelling to the engine will be higher and the temperature of the exhaust gas in the exhaust gas path 28 will be higher. Also exhaust gas recirculation has to be limited at this point as the lambda values will be lower at this operating point. Any introduction of exhaust gas recirculation will lead to sharp increase in smoke emission from the engine. At this time heat transfer from the gas path 28 to chamber 24 is higher leading to expansion of gases inside the chamber 24. This pushes the diaphragm 18 and valve element 16 in downward direction against the spring force. The spring 22 compresses against the valve guide 20. As the valve element 16 is pushed the exhaust gas communication between the exhaust gas path 28 and the inlet manifold 30 is stopped. Thus at higher loads the exhaust gas recirculation valve 10 is shut off.