Claims:We claim:
1.An exhaust gas recirculation valve 10, said exhaust gas recirculation valve 10 comprising:
a valve shim 12;
a valve piston 14 positioned within said valve shim 12, said valve piston 14 comprising:
a shaft 16, said shaft 16 coupled to an actuator 20 and adapted to be actuated by said actuator 20; and
a valve plate 18 formed with said shaft 16, said valve plate 18 adapted to translate within said valve shim 12 when said shaft 16 is actuated by said actuator 20.

2. The exhaust gas recirculation valve 10 in accordance with Claim 1 wherein said valve plate 18 comprises a tapered seat 22 in contact with said valve shim 12, said tapered seat 22 adapted to increase a rate of flow of exhaust gas through said exhaust gas recirculation valve 10 when said valve plate 18 translates within said valve shim 12.

3. The exhaust gas recirculation valve 10 in accordance with Claim 2 wherein said shaft 16 is actuated by said actuator 20 to facilitate moving said valve plate 18, thereby causing a flow of exhaust gas through said exhaust gas recirculation valve 10.

4. The exhaust gas recirculation valve 10 in accordance with Claim 1 wherein said valve plate 18 comprises a notched portion 24 defined on a sidewall of said valve plate 18, said notched portion 24 adapted to clear exhaust gas deposits that are deposited between said valve plate 18 and said valve shim 12.

5. The exhaust gas recirculation valve 10 in accordance with Claim 1 wherein said valve shim 12 comprises a tapered portion 26 in contact with said valve plate 18, said tapered portion 26 of said valve shim 12 in sealing contact with said valve plate 18 to prevent escape of exhaust gas past said valve plate 18 in a closed position of said exhaust gas recirculation valve 10. , Description:Field of the invention:
[0001] This disclosure relates to an exhaust gas recirculation valve.
Background of the invention:
[0002] U.S. Patent Number US3762384A: A diaphragm operated control valve assembly, responsive either to vacuum conditions at an induction passage slot traversed by the edge of the throttle or to the exhaust back pressure, controls recirculation of exhaust gases from the intake manifold exhaust crossover passage to the intake manifold induction passages.
Brief description of the accompanying drawings:
[0003] An embodiment of the disclosure is described with reference to the following accompanying drawings:
[0004] Figure 1 illustrates a front view of an exhaust gas recirculation valve in accordance with this disclosure;
[0005] Figure 2 illustrates a graphical representation of the valve lift of the exhaust gas recirculation valve vs. the quantity of exhaust gas flowing through the exhaust gas recirculation valve;
[0006] Figure 3 illustrates another embodiment of an exhaust gas recirculation valve in accordance with this disclosure; and
[0007] Figure 4 illustrates an exhaust gas duct 30 and exhaust gas recirculation duct 32 containing the exhaust gas recirculation valve 10 and the actuator 20 that is coupled to the exhaust gas recirculation valve 10.

Detailed description of the embodiments:
[0008] An exhaust gas recirculation valve 10 is described. The exhaust gas recirculation valve 10 comprises a valve shim 12 and a valve piston 14 positioned within the valve shim 12. The valve piston 14 comprises a shaft 16, the shaft 16 coupled to an actuator 20 and adapted to be actuated by the actuator 20. A valve plate 18 is formed with the shaft 16, the valve plate 18 adapted to translate within the valve shim 12 when the shaft 16 is actuated by the actuator 20.
[0009] Figure 1 illustrates an exhaust gas recirculation valve 10. The exhaust gas recirculation valve 10 comprises a valve shim 12. The valve shim 12 contains a bore within which the valve piston 14 is inserted. The valve shim 12 also includes a tapered portion 26 that is defined proximate its base portion that mates with the valve piston 14 as will be explained further below.
[00010] The exhaust gas recirculation valve 10 includes a valve piston 14. The valve piston 14 includes a shaft 16 that is coupled to the valve piston 14 and facilitates translating the valve piston 14. The shaft 16 is coupled to an actuator 20 that is controlled by means of an engine control unit (not shown). The exhaust gas recirculation valve 10 is placed within an exhaust gas flow duct and facilitates channeling exhaust gas to an engine. The actuator 20 is coupled to an end portion of the shaft 16 that is located external to the exhaust gas flow duct by means of a bore formed in the exhaust gas flow duct.
[00011] The actuator 20 facilitates translating the shaft 16 to cause exhaust gas to be channeled via the space defined between the valve shim 12 and the valve piston 14. The valve piston 14 also includes a valve plate 18 that is coupled to the shaft 16. In an alternate embodiment, the valve plate 18 is integrally formed on the shaft 16. When the shaft 16 translates due to actuation by means of the actuator 20, the valve plate 18 is translated. The valve plate 18 includes a notched portion 24 that is coupled to the valve plate 18. The notched portion 24 facilitates clearing exhaust gas deposits that are formed between the valve plate 18 and the valve shim 12. In an embodiment, the notched portion 24 may be coupled anywhere on the surface of the valve plate 18 and facilitates clearing exhaust gas deposits that are formed between the valve plate 18 and the valve shim 12.
[00012] The valve plate 18 includes a tapered seat 22 that synchronizes with the tapered portion 26 of the valve shim 12 in its closed position, such that no exhaust gas flows through the valve plate 18. When the valve plate 18 is actuated in the downward direction by means of the actuator 20, exhaust gas is channeled through the gap provided between the valve plate 18 and the valve shim 12. During the primary stages of movement of the valve plate 18, throttling occurs in the gap between the valve shim 12 and the valve plate 18. Moreover, the gap between the tapered portion 26 of the valve shim 12 and the tapered seat 22 of the valve plate 18 is low. Therefore, the volume of exhaust gas that is channeled through the gap provided between the valve plate 18 and the valve shim 12 is low. As the valve plate 18 is actuated further by means of the actuator 20, a greater quantity of exhaust gas is channeled through the gap created between the valve plate 18 and the valve shim 12. The actuator 20 that is controlled by means of the engine control unit is adapted to translate the valve plate 18 in the upward direction after the exhaust gas is completely discharged to facilitate sealing the tapered seat 22 of the valve plate 18 against the tapered portion 26 of the valve shim 12.
[00013] Figure 2 illustrates a graphical representation of the lift of the exhaust gas recirculation valve 10 vs. the quantity of exhaust gas flowing through the exhaust gas recirculation valve 10. During the initial lift of the valve plate 18 by means of the actuator 20, the quantity of exhaust gas that flows through the valve plate 18 is low as is depicted in the graphical representation. As the lift of the valve plate 18 by means of the actuator 20 increases, the quantity of exhaust gas that flows through the valve plate 18 increases. At the maximum lift of the valve plate 18, the quantity of exhaust gas that flows through the valve plate 18 is maximum and does not increase beyond the maximum as is illustrated in the graphical representation.
[00014] Figure 3 illustrates an exhaust gas recirculation valve 10. The exhaust gas recirculation valve 10 comprises a valve shim 12. The valve shim 12 contains a bore within which the valve piston 14 is inserted. The valve shim 12 also includes a flat portion that is defined proximate its base portion that mates with the valve piston 14 as will be explained further below.
[00015] The exhaust gas recirculation valve 10 includes the valve piston 14. The valve piston 14 includes the shaft 16 that is coupled to the valve piston 14 and facilitates translating the valve piston 14. The shaft 16 is coupled to the actuator 20 that is controlled by means of the engine control unit (not shown). The actuator 20 facilitates translating the shaft 16 to cause exhaust gas to be channeled via the space defined between the valve shim 12 and the valve piston 14. The valve piston 14 also includes the valve plate 18 that is coupled to the shaft 16. In an alternate embodiment, the valve plate 18 is integrally formed on the shaft 16. When the shaft 16 translates due to actuation by means of the actuator 20, the valve plate 18 is translated. The valve plate 18 includes a notched portion 24 that is coupled to a base portion of the valve plate 18. The notched portion 24 facilitates clearing exhaust gas deposits that are formed between the valve plate 18 and the valve shim 12. In an embodiment, the notched portion 24 may be coupled anywhere on the surface of the valve plate 18 and facilitates clearing exhaust gas deposits that are formed between the valve plate 18 and the valve shim 12.
[00016] Figure 4 illustrates an exhaust gas duct 30 and exhaust gas recirculation duct 32 containing the exhaust gas recirculation valve 10 and the actuator 20 that is coupled to the exhaust gas recirculation valve 10 via the shaft 16. Exhaust gas is channeled from the exhaust gas duct 30 to the exhaust gas recirculation duct 32 via the exhaust gas recirculation valve 10. The exhaust gas recirculation valve 10 may be actuated by the actuator 20 to facilitate channeling exhaust gas from the exhaust gas duct 30 to the exhaust gas recirculation duct 32 at various engine operating conditions such as engine speed, engine torque, and the like.
[00017] The working of the exhaust gas recirculation valve 10 is described as an example. When it is required to supply exhaust gas through the valve plate 18, the actuator 20 actuates the valve plate 18 in the downward direction. Due to separation between the tapered portion 26 of the valve shim 12 and the tapered seat 22 of the valve plate 18, a small quantity of exhaust gas is channeled through the gap formed between the tapered portion 26 of the valve shim 12 and the tapered seat 22 of the valve plate 18. As the actuator 20 actuates the valve plate 18 further in the downward direction, the greater separation between the tapered portion 26 of the valve shim 12 and the tapered seat 22 of the valve plate 18 causes a higher quantity of exhaust gas to be channeled through the gap formed between the tapered portion 26 of the valve shim 12 and the tapered seat 22 of the valve plate 18. When it is required to seal the valve plate 18 against the valve shim 12, the actuator 20 actuates the valve plate 18 in the upward direction such that the tapered portion 26 of the valve shim 12 is sealed against the tapered seat 22 of the valve plate 18.
[00018] It should be understood that embodiments explained in the description above are only illustrative and do not limit the scope of this invention. Many such embodiments and other modifications and changes in the embodiment explained in the description are envisaged. The scope of the invention is only limited by the scope of the claims