Claims:We claim:

1. An improved exhaust gas recirculation (EGR) system for diesel engine, the EGR system comprises:

• an intake line connected to atmosphere via an air-filter;
• an exhaust gas recirculation (EGR) pipe exiting from the exhaust manifold;
• an exhaust gas recirculation (EGR) housing connected to EGR pipe at one end thereof and to an EM-EGR valve connected at the other end thereof, which in turn is electrically connected to ECU via a controller;
• a coolant supply line and a coolant discharge line connected to the EGR housing;
• a mixing pipe for mixing cooled EGR incoming from one end thereof and filtered air incoming from the other end thereof and the air mixed with EGR leading to intake manifold of the diesel engine for combustion therein; and
• an exhaust manifold connected to the muffler and tail pipe discharging the spend exhaust gases to the atmosphere passing through a diesel oxidation catalyst chamber;

wherein the exhaust gas recirculation (EGR) housing includes a casted outer body supporting a profiled coolant core for passing coolant therethrough for cooling exhaust gases recirculated through the EGR housing and a profiled exhaust core disposed within the coolant core, the exhaust gases recirculated being cooled in the exhaust core before mixing with filtered fresh atmospheric air by the coolant flowing through the profiled coolant core disposed around it.

2. Exhaust gas recirculation (EGR) system as claimed in claim 1, wherein the profiled coolant core surrounds the exhaust core configured as a cylindrical body through which recirculated exhaust gases are passed for cooling thereof.

3. Exhaust gas recirculation (EGR) system as claimed in claim 1, wherein the coolant inlet and coolant outlet of the coolant core are disposed in a direction opposite to the recirculated exhaust gas direction.

4. Exhaust gas recirculation (EGR) system as claimed in claim 1, wherein the EM-EGR valve is directed mounted on the outlet face of the exhaust core.

5. Exhaust gas recirculation (EGR) system as claimed in claim 4, wherein the EM-EGR valve controls the EGR cooling by controlling the EGR flow through the exhaust core.

6. Exhaust gas recirculation (EGR) system as claimed in claim 5, wherein the EGR controller controls the EGR flow as a function of signals received from ECU based on targeted diesel engine emissions to the atmosphere.

7. An improved exhaust gas recirculation (EGR) system for diesel engine, the EGR system comprises:

• an intake line connected to atmosphere via an air-filter;
• an exhaust gas recirculation (EGR) pipe exiting from the exhaust manifold;
• an exhaust gas recirculation (EGR) housing connected to EGR pipe at one end thereof and to an EM-EGR valve connected at the other end thereof, which in turn is electrically connected to ECU via a controller;
• a coolant supply line and a coolant discharge line connected to the EGR housing;
• a mixing pipe for mixing cooled EGR incoming from one end thereof and filtered air incoming from the other end thereof and the air mixed with EGR leading to intake manifold of the diesel engine for combustion therein; and
• an exhaust manifold connected to the muffler and tail pipe discharging the spend exhaust gases to the atmosphere passing through a diesel oxidation catalyst chamber;

wherein the exhaust gas recirculation (EGR) housing includes a casted outer body supporting a profiled coolant core for passing coolant therethrough for cooling exhaust gases recirculated through the EGR housing and a profiled exhaust core disposed within a coolant jacket surrounding a cylindrical exhaust core or pipe for passing the recirculated exhaust gases to be cooled by a coolant flowing through the coolant jacket disposed around the exhaust core, before being mixed with filtered atmospheric air.

8. Exhaust gas recirculation (EGR) system as claimed in claim 7, wherein the coolant inlet and coolant outlet of the coolant jacket are configured in a direction opposite to the direction of recirculation of the exhaust gas.

9. Exhaust gas recirculation (EGR) system as claimed in claim 1, wherein the EM-EGR valve is directed mounted on the outlet face of the exhaust core to control the cooling of the EGR by regulating the EGR flow through the exhaust core by means of an EGR controller for controlling the EGR flow as a function of signals received from ECU based on targeted diesel engine emissions to the atmosphere.

10. A method for improving the exhaust gas recirculation (EGR) system for a diesel engine, wherein the method comprises the steps of:

• Filtering fresh air by means of an air-filter;

• Tapping a portion of the EGR for recirculation for optimizing combustion;

• Cooling the recirculated by means of an EGR system composed of a cylindrical exhaust core surrounded by a profiled coolant core configured as a coolant jacket with a coolant inlet and a coolant outlet;

• controlling the cooled EGR flow by means of an EGR controller as a function of signals received from ECU based on targeted diesel engine emissions to the atmosphere;

• mixing filtered air with the cooled and controlled quantity of recirculated exhaust gases for subsequent combustion in the diesel engine; and
• passing the remainder exhaust gases through the diesel oxidation catalyst 118 before being discharged to atmosphere via a muffler and tail pipe.

Dated: this 27th day of September, 2016. SANJAY KESHARWANI
APPLICANT’S PATENT AGENT , Description:FIELD OF INVENTION

The present invention relates to the emission control system in internal combustion engines. In particular, the present invention relates to a simplified exhaust gas recirculation system for diesel engines. More particularly, the present invention relates to an EGR housing, which prevents EGR valve lacquering in diesel engines.

BACKGROUND OF THE INVENTION

Exhaust gas recirculation (EGR) is technology to reduce nitrogen oxide (NOx) emissions in internal combustion engines (ICEs), i.e. petrol and diesel engines. This technology is based on recirculating a portion of exhaust gases of the engine back to the engine cylinders for the recovery of heat contained therein.

NOx is formed when a mixture of nitrogen and oxygen is subjected to high temperature. EGR thus facilitates the exhaust gases generated in diesel engine to replace some of the excess oxygen in the pre-combustion mixture. The exhaust gas recirculation lowers the combustion chamber temperatures and thereby it reduces NOx generated during the combustion process.

Exhaust Gas Recirculation Cooler uses the engine coolant for reducing the exhaust gas temperature before recirculation thereof through the intake system of the engine. Reducing engine combustion temperature helps prevent the formation of Oxides of Nitrogen (NOx) pollutants.

The exhaust gas recirculation also lowers the combustion chamber temperatures and thereby it further reduces NOx generated during the combustion process.

In addition, EGR system also reduces thermal stresses on the cylinder head gaskets and intake and exhaust valves, which may significantly contribute to increase the service life of the component involved.
In view of ever increasing effect of the greenhouse gas effect on the environment, national and international legislations are continuously making the emission standards more and more stringent for fossil fuel based combustion engines. Apart from European Emission Standards (Euro 1-6) and US Standards (Tier I and II) managed by EPA, various emission standards (Tier II limit values, Level II CARB limit values) have been introduced.

However, most countries in Asia as well as North and South America have adopted these EU and US standards. Therefore, to meet ever stringent emissions standards these days, the exhaust gas recirculation (EGR) system generally forms an essential part of diesel engines, which is designed to take into account of various limit values prescribed by these EP and US Emission standards.

PRIOR ART

In particular, engine efficiency can be increased by using an EGR cooler, which reduces the exhaust gas temperatures before mixing them with fresh intake air.

Accordingly, a portion of the exhaust gases discharged from the engine is recirculated back into the intake air. This amount of recirculated exhaust gases is controlled by a valve, often referred to as EGR valve, which may be opened to control the flow of exhaust gases or even close this exhaust gas flow completely, if required.

DISADVANTAGES WITH THE PRIOR ART

However, if this EGR valve is placed on cold side of the engine, a lacquering occurs on the EGR valve seat, which obstructs the movement of the EGR valve, thereby making it non-functional.

A non-functioning EGR valve substantially affects the emissions discharged from the diesel engine.

Therefore, there is an existing need for improving the EGR system, particularly by avoiding EGR valve lacquering and by eliminating the EGR cooler.
OBJECTS OF THE INVENTION

Some of the objects of the present invention - satisfied by at least one embodiment of the present invention - are as follows:

An object of the present invention is to provide an improved EGR system which reduces the combustion chamber temperatures in diesel engines.

Another object of the present invention is to provide an improved EGR system which avoids formation of lacquering on EGR valve seats.

Still another object of the present invention is to provide an improved EGR system which eliminates the use of EGR cooler to reduce overall cost of the EGR system.

Yet another object of the present invention is to provide an improved EGR system which safeguards the electromotive EGR valve from high-temperature seizure.

A still further object of the present invention is to provide an improved EGR system which helps in complying with ever stringent emission standards.

These and other objects and advantages of the present invention will become more apparent from the following description, when read with the accompanying figures of drawing, which are however not intended to limit the scope of the present invention in any way.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided an improved exhaust gas recirculation (EGR) system for diesel engine, the EGR system comprises:

• an intake line connected to atmosphere via an air-filter;
• an exhaust gas recirculation (EGR) pipe exiting from the exhaust manifold;
• an exhaust gas recirculation (EGR) housing connected to EGR pipe at one end thereof and to an EM-EGR valve connected at the other end thereof, which in turn is electrically connected to ECU via a controller;
• a coolant supply line and a coolant discharge line connected to the EGR housing;
• a mixing pipe for mixing cooled EGR incoming from one end thereof and filtered air incoming from the other end thereof and the air mixed with EGR leading to intake manifold of the diesel engine for combustion therein; and
• an exhaust manifold connected to the muffler and tail pipe discharging the spend exhaust gases to the atmosphere passing through a diesel oxidation catalyst chamber;

wherein the exhaust gas recirculation (EGR) housing includes a casted outer body supporting a profiled coolant core for passing coolant therethrough for cooling exhaust gases recirculated through the EGR housing and a profiled exhaust core disposed within the coolant core, the exhaust gases recirculated being cooled in the exhaust core before mixing with filtered fresh atmospheric air by the coolant flowing through the profiled coolant core disposed around it.

Typically, the profiled coolant core surrounds the exhaust core configured as a cylindrical body through which recirculated exhaust gases are passed for cooling.

Typically, the coolant inlet and coolant outlet of the coolant core are disposed in a direction opposite to the recirculated exhaust gas direction.

Typically, the EM-EGR valve is directed mounted on the outlet face of the exhaust core.

Typically, the EM-EGR valve controls the EGR cooling by controlling the EGR flow through the exhaust core.

Typically, the EGR controller controls the EGR flow as a function of signals received from ECU based on targeted diesel engine emissions to the atmosphere.
According to the present invention, there is also provided an improved exhaust gas recirculation (EGR) system for diesel engine, comprising:

• an intake line connected to atmosphere via an air-filter;
• an exhaust gas recirculation (EGR) pipe exiting from the exhaust manifold;
• an exhaust gas recirculation (EGR) housing connected to EGR pipe at one end thereof and to an EM-EGR valve connected at the other end thereof, which in turn is electrically connected to ECU via a controller;
• a coolant supply line and a coolant discharge line connected to the EGR housing;
• a mixing pipe for mixing cooled EGR incoming from one end thereof and filtered air incoming from the other end thereof and the air mixed with EGR leading to intake manifold of the diesel engine for combustion therein; and
• an exhaust manifold connected to the muffler and tail pipe discharging the spend exhaust gases to the atmosphere passing through a diesel oxidation catalyst chamber;

wherein the exhaust gas recirculation (EGR) housing includes a casted outer body supporting a profiled coolant core for passing coolant therethrough for cooling exhaust gases recirculated through the EGR housing and a profiled exhaust core disposed within a coolant jacket surrounding a cylindrical exhaust core or pipe for passing the recirculated exhaust gases to be cooled by a coolant flowing through the coolant jacket disposed around the exhaust core, before being mixed with filtered atmospheric air.

Typically, wherein the coolant inlet and coolant outlet of the coolant jacket are configured in a direction opposite to the direction of recirculation of exhaust gas.

Typically, the EM-EGR valve is directly mounted on the outlet face of the exhaust core to control the cooling of the EGR by regulating the EGR flow through the exhaust core by means of an EGR controller for controlling the EGR flow as a function of signals received from ECU based on targeted diesel engine emissions to the atmosphere.

In accordance with the present invention, there is also provided a method for improving the exhaust gas recirculation (EGR) system for a diesel engine, wherein the method comprises the steps of:

• Filtering fresh air by means of an air-filter;

• Tapping a portion of the EGR for recirculation for optimizing combustion;

• Cooling the recirculated by means of an EGR system composed of a cylindrical exhaust core surrounded by a profiled coolant core configured as a coolant jacket with a coolant inlet and a coolant outlet;

• controlling the cooled EGR flow by means of an EGR controller as a function of signals received from ECU based on targeted diesel engine emissions to the atmosphere;

• mixing filtered air with the cooled and controlled quantity of recirculated exhaust gases for subsequent combustion in the diesel engine; and

• passing the remainder exhaust gases through the diesel oxidation catalyst 118 before being discharged to atmosphere via a muffler and tail pipe.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The present invention will be briefly described with reference to the accompanying drawings, wherein:

Figure 1 shows a block diagram of the conventional EGR system configured with an EGR cooler.

Figure 2 shows a perspective view of the three-dimensional layout of the conventional EGR system configured with an EGR cooler depicted in Figure 1.

Figure 3 shows the detailed arrangement of the EGR cooler for the conventional EGR system depicted in Figure 1.

Figure 4 shows a block diagram of the EGR system replacing the EGR cooler with EGR housing configured in accordance with the present invention.

Figure 5 shows a perspective view of the three-dimensional layout of the EGR system of Figure 4.

Figure 6 shows a perspective view of the arrangement of the EGR housing for the improved EGR system depicted in Figure 5.

Figure 7a shows a perspective view of the EGR housing configured for the improved EGR system depicted in Figure 5.

Figure 7b shows another perspective view of the EGR housing configured for the improved EGR system 100 depicted in Figure 5.

Figure 8 shows a perspective view of the EGR housing with coolant pipe connected thereto and the shaded CFD coding on the margin for indicating the prevailing temperatures at different regions thereof.

Figure 9 shows a perspective views of the EGR pipe, poppet valve and EGR housing and including the shaded CFD coding on the margin for indicating the prevailing temperatures at different regions thereof.

Figure 10 shows a perspective views of the coolant core depicting the valve guide including the shaded CFD coding for indicating the prevailing temperatures on different regions thereof.

DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS

In the following, the EGR system configured in accordance with the present invention will be described in more details with reference to the accompanying drawings without limiting the scope and ambit of present invention in any way.

Figure 1 shows a block diagram of the conventional EGR system 10 configured with an EGR cooler 20. It has a diesel engine 12 having an intake manifold 14 connected to an EGR cooler 20 and an exhaust manifold 16 connected to diesel oxidation catalyst 18. Atmospheric air is sucked in through an air filter 22. The exhaust gases taken from exhaust manifold 16 are recirculated via EGR pipe 17 and passed through EGR cooler 20 for controlled cooling by means of an EGR controller which is supplied with signals 30 from ECU. The recirculated exhaust gas is cooled by means of heat carried away by the engine coolant supplied via coolant inlet pipe 26 and taken out via coolant outlet pipe 28. The cooled recirculated exhaust gas and filtered fresh air are mixed in the mixing pipe 24. The major portion of the exhaust gases exiting from the exhaust manifold 16 are passed through the diesel oxidation catalyst 18 before being discharged to atmosphere via a muffler and tail pipe.

Figure 2 shows a perspective view of the three-dimensional layout of the conventional EGR system configured with an EGR cooler 20 depicted in Figure 1. EGR cooler 20 is connected at one end thereof to the EGR pipe 17 and at the other end thereof to the EM-EGR valve 32 connected to the mixing pipe 24 supplied with fresh air through the intake pipe 23 connected to the air filter 22.

Figure 3 shows the detailed arrangement of the EGR cooler 20 for the conventional EGR system 10 depicted in Figure 1. The EGR cooler 20 is of shell and tub construction. It is configured as a counter flow heat exchanger having exhaust gases entering through exhaust gas inlet 25 and exiting through exhaust gas outlet 29. Coolant flows into the cooler 20 through coolant inlet 27 and exits through coolant outlet 28. The EGR cooler 20 is made of Stainless Steel (SS) and SS separation tubes 27 carry the recirculated exhaust gases to be cooled (flowing leftwards in figure) which are cooled by the coolant flowing outside in an opposite direction (flowing rightwards in figure). Here, the cooling of the recirculated exhaust gases takes place before the EGR valve 32 seat area (Figure 1). Due to rapid cooling of the recirculated exhaust gases, normally there is high probability of the formation of liquid or lacquer in gas flow path, which is accumulated in this valve seat area. This lacquering often obstructs EGR valve movement and makes it non-functional, thereby significantly affecting the emissions discharged from the diesel engine.

Figure 4 shows a block diagram of the EGR system 100 replacing the EGR cooler 20 with an EGR housing 120 configured in accordance with the present invention. It includes a diesel engine 112 having an intake manifold 114 connected to an EGR housing 120 via a mixing pipe 124 and an EGR controller 132 and an exhaust manifold 116 connected to diesel oxidation catalyst 118 and an exhaust tapping pipe 117 for recirculating a portion of the exhaust gases for optimizing and cleaning exhaust gases discharged into atmosphere for complying with stringent environmental regulations. Atmospheric air is sucked in through an air filter 122. The exhaust gases taken from exhaust manifold 116 are recirculated via EGR pipe 117 and passed through EGR housing 120 provided with coolant core configured as a casted cooling jacket for cooling the recirculated exhaust gases before mixing them with the filtered fresh atmospheric air.

For this purpose, the recirculated exhaust gas is cooled by means of heat carried away by the engine coolant supplied via coolant inlet pipe 126 and taken out via coolant outlet pipe 128. EM-EGR valve 132 is protected by the EGR controller supplied with signals 130 from ECU.
The recirculated cooled exhaust gas and filtered fresh air sucked via intake pipe 123 are mixed in the mixing pipe 124. The major portion of the exhaust gases exiting from the exhaust manifold 116 are passed through the diesel oxidation catalyst 118 before being discharged to atmosphere via a muffler and tail pipe.

Figure 5 shows a perspective view of the three-dimensional layout of the EGR system 100 of Figure 4. It includes an exhaust manifold 116, an EGR pipe 117, an EGR housing 120, an EM-EGR valve 132, an intake pipe 123, an inlet coolant inlet pipe 126 and a coolant outlet pipe 128. The uniqueness of the construction of EGR housing 120 is that the EM-EGR valve 132 is directly mounted thereon to control the rate of EGR flow depending on the demand raised by the ECU for desired exhaust gas emissions from the diesel engine. This controlled EGR cooling in EGR housing 120 configured as a simple casted core for EGR cooling is unlike the cooling achieved by using a separate EGR cooler 20 in the conventional EGR system 10 (Figure 2).

This arrangement successfully eliminates any lacquer formation on seat area of the EGR valve 132 and also protects EM-EGR valve 132 from the high temperature seizure.

Figure 6 shows a perspective view of the arrangement of the EGR housing 120 for the improved EGR system depicted in Figure 5. Here, the recirculated exhaust gases enter through an exhaust gas inlet 125 into the profiled exhaust core 134 fitted inside the coolant core 127 mounted on the casted outer body 136. The coolant core 127 includes a coolant inlet 126 and a coolant outlet 128, which are connected to the coolant core 127 disposed circumferentially about the profiled exhaust core 134 to impart better cooling of the recirculated exhaust gases passing therethrough.

Figure 7a shows a perspective view of the EGR housing 120 configured for the improved EGR system 100 depicted in Figure 5. In this arrangement, there is no coolant flow through the EGR housing 120, but coolant flows through the coolant core 127 shown in Figure 6.

Figure 7b shows another perspective view of the EGR housing 120 configured for the improved EGR system 100 depicted in Figure 5. Here, the coolant flows through coolant core 127 shown in Figure 6. There is no lacquer formation in the recirculated exhaust gas flow path 125-129. EM-EGR valve 132 can be mounted on the side of the EGR housing 120 for exiting cooled exhaust 129.
Figure 8 shows a perspective view of the EGR housing with coolant pipe connected thereto. The first view shows the exhaust core face for mounting the EM-EGR valve thereon and the second view shows the flange face thereof. Figure also includes the shaded CFD coding on the margin for indicating the prevailing temperatures on different regions of the EGR housing. From the CFD analysis of the EGR housing, it was confirmed that the flange face reaches a maximum temperature of about 1530C.

Figure 9 shows a perspective views of the EGR pipe, poppet valve and EGR housing depicting the valve guide temperature during CFD analysis including the shaded CFD coding on the margin thereof for indicating the prevailing temperatures on different regions. From the CFD analysis of the EGR housing, it was confirmed that the poppet valve attains a maximum temperature of about 4000C, whereas the valve guide reaches a maximum temperature of 2870C.

Figure 10 shows a perspective views of the coolant core depicting the valve guide during CFD analysis including the shaded CFD coding in the margin thereof for indicating the prevailing temperatures on different regions.

VIRTUAL SIMULATION CORRELATION:

The critical regions on EM-EGR valves were identified and the acceptable limitations thereof derived by virtual simulation correlation. Using this data, in order to meet the acceptance criteria or to avoid valve failure due to high temperatures, the coolant core volume and flow rates were optimized for configuring the EGR housing 120. These values were taken as inputs to be fed into the virtual Computational Fluid Dynamics software to obtain satisfactory EGR housing dimensions after conducting sufficient number of iterations. Accordingly, the shape of the coolant core 127 and its openings 126, 128 are finalized. Subsequently, prototypes of the components are made using the virtual simulation results and designed obtained thereby. These prototypes are compared with the actual engine test results. Based on these test results on engine or vehicle, the virtual CFD correlation was established. Actual results on engine or vehicle are the acceptable limit on the critical regions of EGR valve.

WORKING OF THE INVENTION

Exhaust gases are taken to EGR housing via EGR Pipe. EGR valve is mounted on housing & will control the rate of EGR flow based on ECU demand for engine out Gaseous emissions. This controlled EGR Gas is cooled in housing by proposed simple cored casting cooling method unlike cooling takes place by using separate EGR cooler. With this arrangement lacquer formation on valve seat is completely eliminated and the EM-EGR valve is also protected from the high temperature seizure.

TECHNICAL ADVANTAGES AND ECONOMIC SIGNIFICANCE

The exhaust gas recirculation system for diesel engines configured in accordance with the present invention has the following technical and economic advantages:
• Protects EM-EGR valve from high temperature seizure.

• Effectively cools recirculated exhaust gases on proposed housing.

• Eliminates lacquering on EGR-valve seat area.

• Low-cost of EGR system due to elimination of EGR cooler and because of integrated housing design.

• Simpler layout of the overall EGR system.

• Savings in terms of EGR cooler servicing costs.

• Trouble-free operation and enhanced service life of EGR system.

• Lower down-time during field operation and thus better customer satisfaction.

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. The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description.

The description provided herein is purely by way of example and illustration. The various features and advantageous details are explained with reference to this non-limiting embodiment in the above description in accordance with the present invention.

The descriptions of well-known components and manufacturing and processing techniques are consciously omitted in this specification, so as not to unnecessarily obscure the specification. It is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.
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 preferred embodiments, the skilled person will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments described herein and easily make innumerable changes, variations, modifications, alterations and/or integrations in terms of materials and method used to configure, manufacture and assemble various constituents, components, subassemblies, assemblies and in terms of the size, shapes, orientations and interrelationships without departing from the scope and spirit of the present invention.

The numerical values given of various physical parameters, dimensions and quantities are only approximate values and it is envisaged that the values higher or lower than the numerical value assigned to the physical parameters, dimensions and quantities fall within the scope of the disclosure unless there is a statement in the specification to the contrary.

Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, shall be understood to implies including a described element, integer or method step, or group of elements, integers or method steps, however, does not imply excluding any other element, integer or step, or group of elements, integers or method steps.

The use of the expression “a”, “at least” or “at least one” shall imply using one or more elements or ingredients or quantities, as used in the embodiment of the disclosure in order to achieve one or more of the intended objects or results of the present invention.