Claims:We claim:
1. An exhaust gas recirculation system for an internal combustion engine (200) using a mixture of fresh air and recirculated exhaust gas comprising a cooling means (90) fitted between the air intake port (25) of said engine (200) and the point of confluence of said recirculated exhaust gas and said fresh air, for cooling said mixture of air and recirculated exhaust gas before said mixture enters said air intake port (25).
2. The system as claimed in claim 1, wherein said cooling means (90) comprises:
• a section (52) of a predetermined length of an air intake pipe (50), said section (52) having:
o an inlet port (52a) for air;
o an inlet port (52b) for recirculated exhaust gas; and
o an outlet port (52c) for said mixture flowing out of said cooling means (90) after cooling;
• a jacket (92) configured around said section (52), said jacket (92) configured for allowing a coolant to flow therethrough, said jacket (92) having:
o an inlet port (92a), and
o an outlet port (92b);
wherein said coolant flowing through said jacket (92) absorbs heat from said mixture of said recirculated exhaust gas and air flowing through said section (52).
3. An engine (200) which employs said system of claim 1.
4. An engine (200) which employs said cooling means (90) of claim 2.
A method for feeding a mixture of fresh air and recirculated exhaust gas to an internal combustion engine (200) comprising a step of cooling said mixture prior to the entry of said mixture into the air intake port (25) of said engine (200).
, Description:FIELD
The present disclosure relates to the field of internal combustion engines.
BACKGROUND
The background information herein below relates to the present disclosure but is not necessarily prior art.
Exhaust gas recirculation (EGR) is implemented worldwide with internal combustion engines to reduce nitrogen oxide (NOx) emissions. As exhaust gas temperature is high, after it mixes with fresh air it reduces the density of the engine intake air, thereby affecting volumetric efficiency of the engine. To avoid this, EGR (hereinafter also referring to ‘recirculated exhaust gas’) is either cooled immediately after it is out of the exhaust manifold by an EGR cooler before it mixes with fresh air or fresh air is cooled by an intercooler before it mixes with the EGR. This is the current solution available worldwide to increase the density of intake air which was affected because of mixing EGR with the intake air. Using an intercooler or an EGR cooler significantly increases cost to the engine.
There is, therefore, a system which eliminates the shortcomings of the arrangements as described hereinabove.
OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:
An object of the present disclosure is to provide an exhaust gas recirculation system for an internal combustion engine.
Another object of the present disclosure is to provide an exhaust gas recirculation system for an internal combustion engine, which has high volumetric efficiency.
Yet another object of the present disclosure is to provide an exhaust gas recirculation system for an internal combustion engine, which is does not require costly components.
Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.
SUMMARY
The present disclosure envisages an exhaust gas recirculation system for an internal combustion engine using a mixture of fresh air and recirculated exhaust gas. The exhaust gas recirculation system comprises a cooling means fitted prior to the air intake port of the engine to cool the mixture of air and recirculated exhaust gas before the mixture enters the air intake port.
The mixture of air and is cooled inside the cooling means. The cooling means comprises a section of a predetermined length of an air intake pipe and a jacket configured around the section. The section has an inlet port for air, an inlet port for recirculated exhaust gas and an outlet port for the mixture flowing out of the cooling means after cooling. A coolant flows through the jacket. The jacket has an inlet port and an outlet port.
The coolant flowing through the jacket absorbs heat from the mixture of the recirculated exhaust gas and air flowing through the section.
The present disclosure also envisages a method for feeding a mixture of fresh air and recirculated exhaust gas to an internal combustion engine. The method comprises a step of cooling the mixture prior to the entry of the mixture into the air intake port of the engine.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
An exhaust gas recirculation system for an internal combustion engine of the present disclosure will now be described with the help of the accompanying drawing, in which:
Figure 1 is a schematic block diagram of an exhaust gas recirculation system of prior art;
Figure 2 is a schematic block diagram of an exhaust gas recirculation system of the present disclosure;
Figure 3 illustrates a top view of an internal combustion engine with an exhaust gas recirculation system of the present disclosure;
Figure 4 illustrates an isometric view of an EGR-air mixture cooling pipe of the present disclosure;
Figure 5 illustrates a sectional view of an EGR-air mixture cooling pipe of Figure 3;
Figure 6 is shows plots of temperature inside intake manifold for varying engine torque for an engine with and without the system of the present disclosure;
Figure 7 shows plots of specific fuel consumption of the engine for varying engine torque for an engine with and without the system of the present disclosure; and
Figure 8 shows plots of filter smoke number of engine exhaust for varying engine torque for an engine with and without the system of the present disclosure.
LIST OF REFERENCE NUMERALS
10 engine intake manifold
20 engine cylinder head
25 engine intake port
30 engine exhaust manifold
40 turbocharger
50 air intake pipe
60 EGR valve
70 air cleaner
80 EGR-air mixture pipe
90’ intercooler
90 EGR-air mixture cooling device of the present disclosure
52 section of air intake pipe within EGR-air mixture cooling device
52a inlet for air from turbocharger
52b inlet for EGR
52c EGR-air mixture outlet
92 coolant jacket
92a coolant inlet
92b coolant outlet
200 internal combustion engine
DETAILED DESCRIPTION
Embodiments, of the present disclosure, will now be described with reference to the accompanying drawing.
Embodiments are provided so as to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details are set forth, relating to specific components, and methods, to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.
The terminology used, in the present disclosure, is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms “a”, “an” and “the” may be intended to include the plural forms as well, unless the context clearly suggests otherwise. The terms “comprises”, “comprising”, “including” and “having” are open ended transitional phrases and therefore specify the presence of stated features, integers, steps, operations, elements, modules, units and/or components, but do not forbid the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The particular order of steps disclosed in the method and process of the present disclosure is not to be construed as necessarily requiring their performance as described or illustrated. It is also to be understood that additional or alternative steps may be employed.
When an element is referred to as being “mounted on”, “engaged to”, “connected to” or “coupled to” another element, it may be directly on, engaged, connected or coupled to the other element. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed elements.
Exhaust gas is often recirculated inside internal combustion engines to reduce NOx emissions. Recirculated exhaust gas (also called EGR) is mixed with fresh air taken in, usually from an air filter. Since the EGR is hot, it reduces density of the EGR-air mixture going into the engine and reduces volumetric efficiency of the engine. Therefore, in known art, either the EGR is cooled before mixing with air using an EGR cooler or the filtered air is cooled using an intercooler 90’, as shown in the schematic block diagram of Figure 1. Both these coolers are expensive, which add to the overall cost of the device.
The present disclosure provides an exhaust gas recirculation system for an internal combustion engine 200 using a mixture of fresh air and recirculated exhaust gas and comprising a cooling means 90 fitted prior to the air intake port 25 (not shown in the drawing) of the engine 200 to cool the mixture of air and recirculated exhaust gas before the mixture enters the air intake port 25 (not shown in the drawing).
Referring to the schematic block diagram of Figure 2, the working of the exhaust gas recirculation system of the present disclosure implemented into an internal combustion engine 200 is explained hereforth. Fresh air to be supplied into the engine 200 is usually filtered by an air cleaner 70 and is compressed by a turbocharger 40. The turbocharger 40 is driven by the pressure of a portion of the exhaust gas that comes out of the exhaust manifold 20 of the engine 200. After driving the turbocharger 40, the exhaust gas drops in pressure. This exhaust gas flows out into the atmosphere generally through a muffler (not shown in the drawing). The remaining portion of the exhaust gas goes towards an exhaust gas recirculation valve 60 (i.e., EGR valve 60). The EGR (i.e. exhaust gas for recirculation OR recirculated exhaust gas) flows from the EGR valve 60 into the cooling device 90 of the present disclosure, wherein the filtered and compressed air also arrives from the air intake pipe 50. A mixture of the recirculated exhaust gas and the filtered and compressed air is formed in the cooling device 90. This mixture undergoes cooling inside the cooling device 90, which is supplied with a coolant from a pump (not shown in the drawing). Combustion of fuel occurs inside the combustion chamber (not shown in the drawing) of the engine 200 which is fed with the EGR-air mixture from the intake manifold 10 and a new volume of exhaust gas is formed. This exhaust gas flows out of the combustion chamber into the exhaust manifold 30 of the engine 200. Thereafter, it flows out to partake in the cycle as described hereinabove. A top view of the engine 200 with the exhaust gas recirculation system of the present disclosure is illustrated in Figure 3.
Construction of the cooling device 90 of the present disclosure is explained hereforth with the help of Figure 4 and Figure 5. The cooling device 90 comprises a section 52 of a predetermined length of an air intake pipe 50. The section 52 has an inlet port 52a for air, an inlet port 52b for the recirculated exhaust gas and an outlet port 52c for the mixture flowing out of the cooling device 90 after cooling. According to the embodiment illustrated in Figure 3, Figure 4 and Figure 5, the section 52 is a bent pipe with 90° orientation of the outlet port 52c with respect to the air inlet port 52a. A jacket 92 is configured around the section 52 for a coolant such as water from a water pump (not shown) to flow therethrough. The jacket 92 has an inlet port 92a and an outlet port 92b. Water flows through the jacket 92 over the section 52 and absorbs heat from the EGR-air mixture. The coolant flowing through the jacket 92 absorbs heat from the mixture of the recirculated exhaust gas and air flowing through the section 52.
The cooling device 90 can be manufactured with the same material as that of the inlet pipe 50, which may be aluminum or cast iron or even a polymer composite, and can be made by casting in two parts and joining them together by welding, by blow molding or any other suitable manufacturing process.
Length of the section, length of the jacket, mass flow rate or pressure of the coolant (e.g., water), mass flow rate or pressure of the fresh air, proportion of exhaust gas that is diverted for recirculation are all optimized based on theoretical calculations and analysis of test data, to achieve optimum performance of the engine.
The construction of the cooling device 90 is highly simplified and therefore easy to manufacture, as compared to the costly intercoolers or EGR coolers of prior art. Compared with an intercooler, the EGR-air mixture cooling device 90 is essentially a simple shell-and-tube heat exchanger in principle, does not require any aluminum foils or a complex manufacturing process. An intercooler or a radiator is often obtained from external suppliers by vehicle manufacturers, whereas the cooling device 90 can be manufactured at a reduced cost in-house. Also, compared with a radiator or an intercooler, the cooling device 90 is compact and lower in weight. Therefore, manufacturing cost of the exhaust gas recirculation system of the present disclosure is significantly lower than that of prior art.
The performance of the internal combustion engine with exhaust gas recirculation system of the present disclosure was evaluated through a series of measurements. Various performance parameters of the engine were quantified. Temperature inside the engine intake manifold, specific fuel consumption and filter smoke number of the engine exhaust, particularly their variations with increasing engine torque at constant RPM, are plotted against corresponding plots for an engine without the exhaust gas recirculation device of the present disclosure, in Figure 6, Figure 7 and Figure 8 respectively.
It can be inferred from Figure 6 that the effect of the exhaust gas recirculation system of the present disclosure is to significantly lower the engine intake manifold temperature. A minimum of 8°C and a maximum of 14°C of temperature difference can be observed between corresponding points in the plots of Figure 6. The result of a lower intake manifold temperature is to increase density of the EGR-air mixture and consequently increase the volumetric efficiency of the engine.
Figure 7 shows a reduction in specific fuel consumption (SFC) of the engine due to use of the exhaust gas recirculation system of the present disclosure. The drop in SFC is more pronounced for higher torque values.
From Figure 8, it can be inferred that the filter smoke number (FSN) of the engine drops significantly due to use of the exhaust gas recirculation system of the present disclosure. FSN is an empirical number for quantifying soot concentration in exhaust gases of engines. The reduction in FSN goes on increasing with an increase in engine torque, and is more significant for higher engine torque values. Figure 8 clearly suggests a reduction in unburnt soot components of the exhaust gas achieved by implementing the system of the present disclosure.
The terms first, second, third, etc., should not be construed to limit the scope of the present disclosure as the aforementioned terms may be only used to distinguish one element, component, region, layer or section from another component, region, layer or section. Terms such as first, second, third etc., when used herein do not imply a specific sequence or order unless clearly suggested by the present disclosure.
Terms such as “inner”, “outer”, “beneath”, “below”, “lower”, “above”, “upper” and the like, may be used in the present disclosure to describe relationships between different elements as depicted from the figures.
The foregoing description of the embodiments has been provided for purposes of illustration and not intended to limit the scope of the present disclosure. Individual components of a particular embodiment are generally not limited to that particular embodiment, but, are interchangeable. Such variations are not to be regarded as a departure from the present disclosure, and all such modifications are considered to be within the scope of the present disclosure.
TECHNICAL ADVANCEMENTS
The present disclosure described herein above has several technical advantages including, but not limited to, the realization of an exhaust gas recirculation system for an internal combustion engine which:
• gives a low intake manifold temperature, and thereby high volumetric efficiency of the engine;
• gives low specific fuel consumption for the engine;
• gives an engine exhaust with low filter smoke numbers; and
• does not require costly components such as an intercooler.
The foregoing disclosure has been described with reference to the accompanying embodiments which do not limit the scope and ambit of the disclosure. The description provided is purely by way of example and illustration.
The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments 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.
The foregoing description of the specific embodiments 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 preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.
Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.
The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.
While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment as well as other embodiments of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.