Claims:WE CLAIM:
1. An exhaust gas recirculation system (100) of a engine (150), said system (100) comprising:
• a housing (110) having an inlet port (110a) for receiving hot exhaust gases and an outlet port (110b) connected to the intake section of the engine (150);
• a recirculation passage defined between said inlet port (110a) and said outlet port (110b);
• a heat exchanger (10) positioned along said passage for extracting heat from the exhaust gases passing therethrough; and
• a first valve (20) disposed between said inlet port (110a) and said heat exchanger (10) for regulating the proportion of said exhaust gases flowing into said heat exchanger (10).
2. The system (100) as claimed in claim 1, wherein said system (100) further comprises a hot exhaust gas pipe (21) for receiving hot exhaust gases of said engine (150) into said system (100), and a cold exhaust gas pipe (22) for discharging cooled exhaust gases from said system (100) back to the engine intake.
3. The system (100) as claimed in claim 1, wherein said system (100) further comprises coolant hoses (19) for receving a coolant liquid into said system (100) and discharging the coolant liquid from said system (100).
4. The system (100) as claimed in claim 1, wherein said system (100) comprises a second valve (30) disposed upstream of said heat exchanger (10), said second valve (30) configured to receive flow of exhaust gases from said first valve (20) and selectively supply the exhaust gases to said heat exchanger (10) in a first configuration and bypass the exhaust gases from said heat exchanger (10) in a second configuration.
5. The system (100) as claimed in claim 1, wherein displacement of said first valve (20) is configured to be dynamically controlled by an engine control unit based on a feedback provided by a plurality of sensors mounted on said engine (150).
6. The system (100) as claimed in claim 4, wherein said second valve (30) is operated by a vaccum modulator (23), said vacuum modulator (23) being configured to be dynamically controlled by said engine control unit based on a feedback provided by a plurality of sensors mounted on said engine (150).
7. The system (100) as claimed in claim 4 or claim 5, wherein said sensors include temperature sensor, pressure sensor and oxygen sensor.
8. The system (100) as claimed in claim 1, wherein said heat exchanger (10) includes an arrangement of tubes (11) and a gas box (17) to obtain a U-shaped flow passage for flow of exhaust gases.
9. The system (100) as claimed in claim 1, wherein said engine (150) is a diesel engine with pushrod-type actuated two valves per cylinder.

, Description:FIELD
The present disclosure relates to the field of internal combustion engines and more particularly to exhaust gas recirculation (EGR) systems of the internal combustion engines.
BACKGROUND
The background information herein below relates to the present disclosure but is not necessarily prior art.
Typically, an exhaust gas recirculation system (EGR) mounted on an internal combustion engine is comprised of a cooler, a valve, vacuum modulator and a bypass valve, all being separately mounted on the engine. This makes the engine assembly bulky and hence increases overall weight of the engine assembly. Further, to accommodate these components, the number of joints required increases, and hence makes the engine system design complex. Still further, the EGR valve is integrated downstream of the cooler which decreases the efficiency of the EGR system, as downstream section of the cooler is prone to condensation which gives rise to chronic problems such as valve sticking. The combined effect of the above mentioned drawbacks increases system design and manufacturing cost. Moreover, the bulky system design also makes servicing difficult
There is, therefore, felt a need for an exhaust gas recirculation (EGR) system that overcomes the aforementioned drawbacks.
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 (EGR) system that reduces bulk of the exhaust system assembly of a pushrod type actuated two valve per cylinder diesel engine.
Another object of the present disclosure is to provide an exhaust gas recirculation (EGR) system that eliminates inefficient design of the EGR system components.
Still another object of the present disclosure is to provide an exhaust gas recirculation (EGR) system that reduces cost.
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 of a pushrod type actuated two valve per cylinder diesel engine. The exhaust gas recirculation system comprises a housing, a recirculation passage, a heat exchanger, a first valve, a second valve, gas pipes and coolant hoses. The housing has an inlet port for receiving hot exhaust gases and an outlet port connected to the intake section of the engine. The recirculation passage is defined between the inlet port and the outlet port. The heat exchanger is positioned along the passage for extracting heat from the exhaust gases passing therethrough. The first valve is disposed between the inlet port and the heat exchanger for regulating the proportion of the exhaust gases flowing into the heat exchanger.
In an embodiment, exhaust gas recirculation system comprises a second valve disposed upstream of the heat exchanger. The second valve is configured to receive flow of exhaust gases from the first valve and selectively supply the exhaust gases to the heat exchanger in a first configuration and bypass the exhaust gases from the heat exchanger in a second configuration.
Preferably, displacement of the first valve is configured to be dynamically controlled by an engine control unit based on a feedback provided by a plurality of sensors mounted on the engine. Preferably, displacement of the second valve is operated by a vaccum modulator and is configured to be dynamically controlled by an engine control unit based on a feedback provided by a plurality of sensors mounted on the engine. The sensors include temperature sensor, pressure sensor and oxygen sensor.
In na embodiment, the heat exchanger includes an arrangement of tubes and a gas box to obtain a U-shaped flow passage for flow of exhaust gases.
In an embodiment, the engine is a diesel engine with two pushrod pushrod-type actuated two valves per cylinder diesel.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
The EGR system of a vehicle, of the present disclosure, will now be described with the help of the accompanying drawing, in which:
Figure 1 shows an isometric view of a conventional EGR system mounted on an engine of the prior art;
Figure 2 shows a front view of an EGR system mounted on an engine, in accordance with an embodiment of the present disclosure;
Figure 3 illustrates a sectional view of the EGR system of Figure 2; and
Figure 4 shows an isometric view of an embodiment of the present disclosure with a vacuum modulator installed.
LIST OF REFERENCE NUMERALS
10, 10a – heat exchanger
11 – tubes
12 – heat exchanger inlet
14, 14a – coolant inlet
16, 16a – coolant outlet
17 – gas box
18 – housing cooling gallery
19- coolant hoses
20 – first valve
21 – hot exhaust gas pipe
22 – cold exhaust gas pipe
23 - vaccum modulator
30 – second valve
40 - heat exchanger oulet
100, 100a – EGR system
110 – housing
110a – exhaust gas inlet port
110b – exhaust gas outlet port
150 – pushrod type actuated two valve per cylinder diesel 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, elements, modules, units and/or components, but do not forbid the presence or addition of one or more other features, integers, 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.
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 present disclosure envisages an exhaust gas recirculation system (hereinafter referred to as EGR) of an internal combustion engine.
Figure 1 shows a conventional EGR system 100a mounted on an internal combustion engine 150 comprising a heat exchanger 10a and a first valve 20a. The first valve 20a is not housed inside the heat exchanger but instead lies separated from the heat exchanger 10a. This makes the EGR system bulky as the number of joints is increased. Moreover, the location of the first valve 20a is after the heat exchanger 10a which causes EGR valve sticking or valve getting stuck due to condensation while in operation. The above mentioned problems result in an inefficient EGR system which also increases costs involved.
Figures 2 and 3 show an embodiment of the present disclosure EGR system 100 mounted on an engine 150. The EGR system 100 comprises a heat exchanger 10 with a first valve 20 and a second valve 30 housed inside a housing 110. The housing 110 has an exhaust gas inlet port 110a and an exhaust gas outlet port 110b, and a recirculation passage is defined between the ports 110a, 110b. The housing 110 is provided with an internal housing cooling gallery 18 for coolant circulation, facilitating improved thermal stability and increased heat transfer rates. The first valve 20 is positioned inside the recirculation passage between the exhaust gas inlet port 110a and the heat exchanger 10 such that the exhaust gases of the engine 150 first pass through the first valve 20 before passing through the heat exchanger 10. The heat exchanger 10 is in the form of a cooler that is used to cool the exhaust gases of the engine. The flow of the exhaust gases arriving at the exhaust gas inlet port 110a is controlled by the first valve 20. The first valve 20 is an electrically actuated valve controlled by an Engine Control Unit (hereinafter referred to as ECU) (not shown in figure) based on a feedback provided by a plurality of sensors mounted on the engine 150. The ECU is calibrated as per the desired engine performance parameters under various operating conditions. The first valve 20 controls the proportion of the exhaust gas admitted into the EGR system 100 out of the total volume of exhaust gases coming out of the engine, thus facilitating dynamic control over the exhaust gas recirculation rate. Further, the exhaust gases are then made to pass through the tubes 11 in the heat exchanger 10 at inlet 12, where heat transfer of the exhaust gases takes place. A coolant is circulated through the heat exchanger 10. The coolant is let in the heat exchanger 10 through a coolant inlet 14. The coolant absorbs heat of the exhaust gases while passing over the tubes 11 and exits the heat exchanger 10 through a coolant outlet 16. The heat exchanger 10 includes a gas box 17 placed at one end that direct the flow of exhaust gases tubes 11 in a U-shaped flow pattern. Partially cooled exhaust gases pass the upstream set of tubes in the heat exchanger 10, and are redirected back to downstream tubes through a gas box 17, which enables further cooling of the exhaust gases. The coolant coming out of the coolant outlet 16 is again cooled further for recirculating inside the heat exchanger 10. The exhaust gases cooled by the heat exchanger 10 exit through the exhaust gas outlet port 110b provided on the housing 110. A suitable piping arrangement is provided in the recirculation passage for conveying exhaust gases from the exhaust section of the engine 150 to the EGR system 100 and from the EGR system 100 back to the intake system of the engine 150.
In an embodiment, a second valve 30 is provided between the first valve 20 and the heat exchanger 10 such that the second valve 30 is configured to selectively pass the exhaust gases from the first valve 20. Unlike the first valve 20, the second valve 30 is an ON/OFF type valve which operates in only two modes viz. a first mode in which all the exhaust gases arriving through the first valve 20 are directed into the heat exchanger 10 or a second mode in which all the exhaust gases arriving through the first valve 20 are bypassed to the exhaust gas outlet port 110b without cooling. The second valve 30 facilitates bypassing of the exhaust gases through the heat exchanger 10 as required in situations during cold start of the engine or regeneration of a Diesel Particulate Filter (DPF) and Lean NOx Trap (LNT). The second valve 30 is operated by a vacuum modulator 23 (as shown in figure 4) which is controlled by the ECU of the engine. The vacuum modulator 23 is configured to receive signal from the ECU subsequent to which the vacuum modulator 23 controls the flow of vacuum from a vacuum reservoir (not shown in figure) to the second valve 30 for actuation of the second valve 30. The vacuum modulator 23 used is of solenoid type.
The technical advancement obtained with the features of the present disclosure is that the EGR system is compact in construction, as the heat exchanger 10, the first valve 20 and the second valve 30 are housed inside a common housing 110. This results in reduced number of joints that need to be designed between the interfacing components of the EGR system 100, thereby allowing ease of assembly which in turn saves manufacturing time and cost involved. The tubes 11 arranged inside the heat exchanger 10 enables increased heat transfer rate, as the exhaust gases are configured to discharge heat to the coolant for an increased duration, thereby increasing the effectiveness of the heat exchanger 10. As a result, overall cost of the engine system is reduced.
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 EGR system of a pushrod type actuated two valve per cylinder diesel engine (150) engine that:
• is compact in construction and which offers ease of assembly;
• increases efficiency of the heat exchanger by the use of housing cooling gallery and U-shaped gas flow pattern due to internal gas box and tube arrangement;
• reduces cost of the entire EGR system assembly by reducing the number of joints; and
• offers ease of control over exhaust gas flow due to being electrically actuated in various operating modes.
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 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.
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.