CLIAMS:We claim,
1. A mechanical arrangement in an exhaust system (10), said exhaust system comprising an exhaust gas recirculation valve (18) located in an exhaust gas recirculation path (19) and a back pressure valve (16) located in an exhaust path (14) respectively,
characterized in said mechanical arrangement:
a linkage (26) connecting said back pressure valve (16) and said exhaust gas recirculation valve (18) to an accelerator pedal (24).
2. The mechanical arrangement claimed in claim (1), wherein said linkage (26) is a mechanical linkage.
3. The mechanical arrangement claimed in claim (1), wherein said linkage 26 is chosen from a group of linkages like a Bowden cable or a push pull cable or the like.
4. The mechanical arrangement claimed in claim (1), wherein said linkage (26) has comprises a first arm 26(a) and a second arm 26(b).
5. The mechanical arrangement claimed in claim (1), wherein said first arm (26a) of said linkage (26) is fitted between an accelerator pedal (24) and the exhaust gas recirculation valve (18).
6. The mechanical arrangement claimed in claim (1), wherein said second arm (26b) of said linkage (26) which is fitted between an accelerator pedal (24) and the back pressure valve (16).
7. The mechanical arrangement claimed in claim (1), wherein a rigid connection (25) between said first arm (26a) and said second arm (26b) of said linkage (26) ensures that movement of one arm i.e. (26a) or (26b) causes movement of the other arm i.e. (26b) or (26a) respectively.
,TagSPECI:Field of the invention
[0001] This invention relates to a mechanical arrangement in an exhaust gas system.
Background of the invention
[0002] Exhaust gas recirculation systems are utilized in automotive vehicles to reduce engine emissions especially on heavy duty diesel engines. An exhaust gas recirculation system recirculates a part of the exhaust gases into the intake system of the engine, thereby reducing Nitrogen Oxide emissions in the exhaust gas. In the exhaust gas recirculation system, a two-position control exhaust gas recirculation valve is arranged in the exhaust gas recirculation path which interconnects the exhaust manifold and the intake manifold. When the engine starts, the exhaust gas recirculation valve is opened and a part of the exhaust gas is recirculated and sent back to the intake manifold. When the exhaust gas recirculation valve is closed, the exhaust gases are not recirculated back to the intake manifold.
[0003] A United States patent 7963274 discloses a unit including a single actuator which actuates the exhaust gas recirculation valve and a throttle valve between a closed position and an open position. The exhaust gas recirculation valve is installed with an exhaust gas recirculation line, while the throttle valve is installed within an exhaust conduit in which the exhaust gas recirculation line is connected to the exhaust conduit.
Brief description of the accompanying drawings
[0004] An exemplifying embodiment of the invention is disclosed in detail in the description and illustrated in the accompanying drawings:
[0005] Figure 1 illustrates a mechanical arrangement to actuate an exhaust gas recirculation valve in an exhaust gas system in an electronic control unit a vehicle according to one embodiment of the invention.
Detailed description of the invention:
[0006] Fig.1 illustrates a mechanical arrangement in an exhaust system 10 according to one embodiment of the invention. The exhaust system comprising an exhaust gas recirculation valve 18 located in an exhaust gas recirculation path 19 and a back pressure valve 16 located in an exhaust path 14 respectively. The mechanical arrangement comprises a linkage 26 connecting the back pressure valve 16 and the exhaust gas recirculation valve 18 to an accelerator pedal 24.
[0007] As seen in figure 1, the linkage 26 comprises two arms 26a and 26b. A first arm 26a which is fitted between an accelerator pedal 24 and the exhaust gas recirculation valve 18 and a second arm 26b which is fitted between an accelerator pedal 24 and the back pressure valve 16. There exists a rigid connection 25 between the first arm 26a and the second arm 26b. The rigid connection 25 ensures that both the first arm 26a and the second arm 26b move together. The rigid connection 25 ensures that movement of one arm i.e. 26a or 26b causes movement of the other arm i.e. 26b or 26a respectively. The construction of the mechanical linkage 26 is such that when the accelerator pedal 24 is not pressed the exhaust gas recirculation valve 18 is fully open allowing all exhaust gas to flow from the exhaust gas path 14 to an air inlet path 20 of the engine 12. Consequently, when the accelerator pedal 24 is not pressed the back pressure valve 16 is fully closed not allowing any exhaust gas to flow downstream from the back pressure valve 16. The linkage 26 is a mechanical linkage and is chosen from a group of linkages like a Bowden cable or a push pull cable or the like.
[0008] An engine assembly comprises an engine 12, an exhaust manifold and an intake manifold. The exhaust gas from the exhaust manifold enters either into the exhaust path 14 or an exhaust gas recirculation path 19. At least a part of the exhaust gas enters the exhaust gas recirculation path 19 and passes through the exhaust gas recirculation valve 18 and remaining exhaust gas passes through the back pressure valve 16 present in the exhaust path 14. The exhaust gas that passes through the exhaust gas recirculation path 19 mixes with fresh air coming from the inlet path 20.
[0009] The working principle of the mechanical arrangement in the exhaust system 10 can be explained as follows. When the accelerator pedal 24 is pressed the mechanical linkage 26 connected to the accelerator pedal 24 (as shown in the figure 1) alters the position of the exhaust gas recirculation valve 18 and the position of the back pressure valve 16. As mentioned earlier since the two arms of the mechanical linkage 26a and 26b are rigidly connected, the position of the exhaust gas recirculation valve 18 and the position of the back pressure valve 16 is altered at the same time. For instance, if the accelerator pedal 24 is pressed 100% (i.e., if the accelerator pedal 24 is pressed fully), then the linkage 26 is operated thereby completely closing the exhaust gas recirculation valve 18 and fully opening the back pressure valve 16. If the accelerator pedal 24 is pressed 50%, then the linkage 26 partially opens both the exhaust gas recirculation valve 18 and the back pressure valve 16. If the accelerator pedal 24 is pressed 0% (i.e. if the accelerator pedal 24 is not pressed), then the linkage 26 completely closes the back pressure valve 16 and fully opens the exhaust gas recirculation valve 18.
[00010] The working of the exhaust gas system 10 as disclosed above can be explained as follows. The working of the exhaust gas system 10 is explained with respect to two conditions i.e. low load condition and high load condition. For the ease of understanding the working of the exhaust gas system 10 as disclosed the low load condition is defined as a condition wherein the accelerator pedal is pressed 10% and a high load condition is defined as a condition wherein the accelerator pedal is pressed 100%. For ease of understanding of this disclosure the exhaust gas system 10 is configured linearly, this means that when the accelerator pedal is pressed 10% of its full range of operation then the exhaust gas recirculation valve 18 closes 10% of its full closing range and the back pressure valve 16 opens 10% of its full opening range. This linear configuration is only descriptive and does not limit the scope of this disclosure to the mentioned linear range configuration.
[00011] During a low load condition, i.e., when the accelerator pedal 24 is 10% pressed, the linkage 26 operates the exhaust gas recirculation valve 18 such that the exhaust gas recirculation valve is closed 10% of its full closing range and the back pressure valve 16 is opened 10% of its full opening range. In order to provide a high exhaust gas recirculation rate, the total amount of exhaust gas coming from the exhaust manifold is made to pass through the exhaust gas recirculation valve 18 by completing closing the back pressure valve 16. Due to high amount of recirculated exhaust gas, passing into the engine 12, the amount of nitrogen oxide present in the exhaust gas will be reduced due to exhaust gas recirculation. During low load conditions, the mechanical arrangement disclosed above increases the exhaust gas recirculation rate and reduces the amount of nitrogen oxide (NOx) in the exhaust gas.
[00012] In a high load condition i.e., when the accelerator pedal 24 is 100% pressed, the linkage 26 operates the back pressure valve 16 such that the back pressure valve 16 is fully open and the linkage 26 operates the exhaust gas recirculation valve 18 such that the exhaust gas recirculation valve 18 in fully closed. In order to reduce the high exhaust gas recirculation rate, the total amount of exhaust gas coming from the exhaust manifold is made to pass through the back pressure valve (by completing closing the exhaust gas recirculation valve). Due to high temperature of the exhaust gas coming from the engine, the amount of soot in a particulate filter is regenerated. During high load condition, the mechanical arrangement disclosed above decreases the exhaust gas recirculation rate thus by reducing the amount of soot accumulated at the filter.
[00013] The mechanical arrangement in the exhaust system 10 disclosed above reduces the amount of nitrogen oxide (NOx) during the low load condition and reduces the amount of soot developed, during the high load condition thus by improving the soot/NOx tradeoff. The mechanical arrangement disclosed also provides a simple and cost effective solution.
[00014] It must be understood that the examples and embodiments of the components explained in the detailed description are only illustrative and do not limit the scope of the invention. The scope of this invention is only limited by the scope of the claims.