Description:TECHNICAL FIELD
[001] The embodiments herein generally relate to engines and more particularly to an exhaust gas re-circulation (EGR) system for the engine. Further, embodiments herein relate to a method for controlling exhaust gas flow to the engine.
BACKGROUND
[002] During the operation of an engine, certain pollutants are emitted out in the exhaust gases. These gases generally consist of oxides of nitrogen (NOx), carbon monoxide (CO) and un-burnt particulate matter (PM). Emission of such pollutants is majorly based on the operating conditions of the engine and the power output of the engine. Due to the harmful nature of these pollutants, the government regulatory bodies have emission norms, which all the engines have to be complying thereto. Exhaust gas recirculation (EGR) is used internal combustion engines to reduce nitrogen oxide (NOx) emissions. EGR technique works by recirculating a portion of an engine's exhaust gas back to the engine’s cylinders resulting in dilution of oxygen in the incoming air stream. This results in reduction of peak combustion temperatures in engines and reduction of NOx emissions.
[003] The temperature at which exhaust gas is re-circulated back into the engine is critical in reducing NOx emissions. The load on the engine determines the temperature of exhaust, and the temperature of the exhaust is critical for reducing NOx. An EGR valve located close to the intake side of the engine, will open a path for exhaust gas to flow and mix with incoming air before the mixture enters the combustion chamber of the IC engine. The opening and/ or closing of EGR valve needs to accurately match the exhaust temperature for effective NOx reduction.
OBJECTS
[004] The principal object of embodiments herein is to provide an exhaust gas re-circulation (EGR) system for an engine which controls operation of EGR valve based on temperature of exhaust gas thereby reducing nitrogen oxides (NOx) emissions.
[005] Another object of embodiments herein is to control opening and / or closing of an EGR valve based on inputs from a temperature sensor which is located on an exhaust pipe.
[006] These and other objects of embodiments herein will be better appreciated and understood when considered in conjunction with following description and accompanying drawings. It should be understood, however, that the following descriptions, while indicating embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.
BRIEF DESCRIPTION OF DRAWINGS
[007] The embodiments are illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which:
[008] Fig. 1 illustrates an exhaust gas re-circulation (EGR) system (100) for an engine, according to embodiments as disclosed herein; and
[009] Fig. 2 illustrates a flowchart indicating steps of a method for controlling exhaust gas re-circulation (EGR) to the engine, according to embodiments as disclosed herein.

DETAILED DESCRIPTION
[0010] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
[0011] Fig. 1 illustrates an exhaust gas re-circulation (EGR) system (100) for an engine. In an embodiment, the EGR system (100) comprises a temperature sensor (102), an exhaust gas re-circulation (EGR) valve (104) and a controller unit (106). The EGR valve (104) is in communication with the controller unit (106). The temperature sensor (102) is located on an exhaust pipe (16). The temperature sensor (102) is adapted to detect and communicate temperature of exhaust gas to the controller unit (106). The temperature sensor is located at 80mm from outlet of the exhaust manifold (14). The controller unit (106) is adapted to operate the EGR valve (104) which in turn regulates exhaust gas flow from the exhaust manifold (14) to the intake manifold (12) via the exhaust pipe (16) based on the temperature of exhaust gas received from the temperature sensor (102).
[0012] The controller unit (106) is configured to receive the temperature of exhaust gas from the temperature sensor (102), compare the measured temperature of the exhaust gas against predefined exhaust gas temperature range, and operate the EGR valve (104) to one of an open position and closed position in accordance the comparison between the measured temperature of the exhaust gas and the predefined exhaust gas temperature range. For the purpose of this description and ease of understanding, the predefined exhaust gas temperature range is defined in a lookup table which is stored in the controller unit (106).

[0013] The table given blow illustrates an example of temperature range defined in the lookup table stored in the controller unit (106). The lookup table stores the predefined exhaust gas temperature range. This lookup table assists controller unit (106) to determine the temperature ranges for which the EGR valve (104) should be open and/ or closed for enabling exhaust-gas recirculation.

Sl. No Measured Temperature Predefined Temperature range Status Of EGR valve
1 100 75-120 OFF/Close
2 150 125-175 ON/Open
3 200 250-300 ON/Open

[0014] Fig. 2 illustrates a flowchart indicating steps of a method (200) for controlling exhaust gas re-circulation (EGR) to an engine (10), according to embodiments as disclosed herein. At step (202), the method (200) comprises, detecting and communicating by a temperature sensor (102) located on an exhaust pipe (16), a temperature of exhaust gas, to a controller unit (106). At step (204), the method (200) includes, receiving, by the controller unit (105), the temperature of exhaust gas from the temperature sensor (102). At step (206), the method (206) includes, comparing, by the controller unit (106), the measured temperature of exhaust gas against predefined exhaust gas temperature range. At step (208), the method (200) includes, operating, by the controller unit (106), the exhaust gas recirculation valve (104) for regulating exhaust gas flow from an exhaust manifold (14) to the intake manifold (12) via the exhaust pipe (16) in accordance to the comparison between the measured temperature of exhaust gas and the predefined exhaust gas temperature range.
[0015] The above-mentioned method is explained with respect to flow of exhaust in the EGR system. Initially a mixture of fuel and air enters the combustion chamber for combustion. Upon combustion and the engine generating power, the exhaust now flows through the exhaust path. It is now considered, for the purpose of better understanding the temperature of exhaust gas to be 200 deg Celsius. This temperature is now sensed by the temperature sensor (102). The temperature sensor (102) is located on an exhaust pipe (16). The temperature sensor (102) is adapted to detect and communicate temperature of exhaust gas to the controller unit (106), in this case 200 deg Celsius. Now the controller unit (106) decides based on the predefined exhaust gas temperature range available in the lookup table if EGR valve (104) should be opened or closed. The controller unit (106) is adapted to operate the EGR valve (104) which in turn regulates exhaust gas flow from the exhaust manifold (14) to the intake manifold (12) via the exhaust pipe (16) based on the temperature of exhaust gas received from the temperature sensor (102).
[0016] Now consider another instance when the temperature of exhaust gas is 100 deg Celsius. Now the controller unit (106) compares the temperature of exhaust gas against the predefined exhaust gas temperature range defined in the lookup table. It is now determined that for 100 deg Celsius exhaust gas temperature, exhaust gas recirculation is not required, this is because at lower temperatures NOx reduction may not be required, or the requirement of exhaust to mix with air in intake manifold may not be necessary. Hence the controller unit (106) closes the EGR valve (104).
[0017] The controller unit (106) compares the exhaust gas temperature as detected by the temperature sensor (102) against predefined exhaust gas temperature range to determine whether opening and or closing of EGR valve is required for regulating exhaust gas flow from the exhaust manifold (14) to the intake manifold (12) via exhaust pipe (16)
[0018] The technical advantages of the EGR system (100) are as follows. The proposed EGR system enables control of EGR valve based on exhaust gas temperature. By controlling the EGR valve opening based on the temperature of exhaust gas flowing through exhaust pipe, it is now possible to reduce NOx for a varied range of exhaust gas temperatures. Further, the EGR system has the flexibility to control EGR valve opening and/ or closing based on temperature of exhaust gas
[0019] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modifications within the spirit and scope of the embodiments as described herein.
, Claims:1. An exhaust gas re-circulation (EGR) system (100) for an engine (10), said EGR system (100) comprising:
a controller unit (106);
an exhaust gas re-circulation (EGR) valve (104) in communication with said controller unit (106); and
a temperature sensor (102) located on an exhaust pipe (16), wherein said temperature sensor (102) is adapted to detect and communicate temperature of exhaust gas to said controller unit (106),
wherein
said controller unit (106) is adapted to operate said EGR valve (104) which in turn regulates exhaust gas flow from the exhaust manifold (14) to the intake manifold (12) via the exhaust pipe (16) based on the temperature of exhaust gas received from said temperature sensor (102).
2. The EGR system (100) as claimed in claim 1, wherein said EGR valve (104) is an electronically controlled valve.
3. The EGR system (100) as claimed in claim 1, wherein said temperature sensor is located at 80mm from outlet of said exhaust manifold (14).
4. The EGR system (100) as claimed in claim 1, wherein said controller unit (106) is configured to:
receive the temperature of exhaust gas from said temperature sensor (102);
compare the measured temperature of the exhaust gas against predefined exhaust gas temperature range; and
operate the EGR valve (104) to one of an open position and a closed position in accordance to the comparison between the measured temperature of the exhaust gas and the predefined exhaust gas temperature range.

5. The EGR system (100) as claimed in claim 4, wherein the predefined exhaust gas temperature range is defined in a lookup table which is stored in said controller unit (106).
6. A method (200) for controlling exhaust gas re-circulation (EGR) to an engine (10), said method (200) comprising:
detecting and communicating (202), by a temperature sensor (102) located on an exhaust pipe (16), a temperature of exhaust gas, to a controller unit (106);
receiving (204), by the controller unit (106), the temperature of exhaust gas from the temperature sensor (102);
comparing (206), by the controller unit (106), the measured temperature of exhaust gas against predefined exhaust gas temperature range; and
operating (208), by the controller unit (106), the exhaust gas re-circulation (EGR) valve (104) to one of an open position and a closed position for regulating exhaust gas flow from an exhaust manifold (14) to the intake manifold (12) via the exhaust pipe (16) in accordance to the comparison between the measured temperature of the exhaust gas and the predefined exhaust gas temperature range.