FORM-2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2006
COMPLETE SPECIFICATION
(See Section 10 and Rule 13)
HEAT EXCHANGER ASSEMBLY FOR HEATING ENGINE
COOLANT
MAHINDRA & MAHINDRA LTD.
an Indian Company of R & D Center, Automotive Division,
89, M.LD.C, Satpur, Nashik - 422 007,
Maharashtra, India
Inventors: 1)PATADE VISHNU
2) VELUSAMY RAMASAMY
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

FIELD OF DISCLOSURE
The present disclosure relates to the field of systems for rapid warm-up of engine when running cold.
Particularly, the present disclosure relates to a heat exchanger assembly for recovering heat from exhaust gases to heat engine coolant.
BACKGROUND
Ever-stricter emission standards for diesel and other internal combustion engines are implemented by countries worldwide to reduce emissions of oxides of nitrogen (NOx), hydrocarbon (HC) and particulate matter. Exhaust gas recirculation (EGR) is a known technique, by which a part of exhaust gases from a combustion process in the combustion engine, are lead back to an inlet duct, with a part of inlet (fresh) air, for supply of the mixture of air and exhaust gases to the combustion engine cylinders, where the combustion takes place. The recirculation of a part of exhaust gases with air to the engine cylinders reduces the concentration of oxygen therein, which in turn lowers the maximum combustion temperature in the cylinders and slows the chemical reactions of the combustion process, resulting in a decrease in the content of nitrogen oxides (NOx) in the exhaust gases produced thereof. Furthermore, the exhaust gases contain unburned hydrocarbons, which due to reintroduction into the combustion chamber, get burned, thus reducing the emission of undesirable pollutants from the internal combustion engine.

Some engines, especially diesel engines, provide coolers for cooling the exhaust gases being re-circulated. The cooled exhaust gases have a decreased latent heat content which aids in lowering engine combustion temperatures even further, which in turn assists in lowering the NOx emissions, and therefore meeting the increasing requirements for reduced emissions. Hence, extensive research has been done in the past on systems for recovering heat from exhaust gases, some of these exhaust gas recirculation systems for cooling the re-circulated exhaust gases are disclosed in the prior art below:
US7594398 discloses an exhaust gas recirculation system for an internal combustion engine. The internal combustion engine includes a crankcase having a plurality of cylinders; an exhaust system is in fluid communication with the plurality of cylinders and includes a turbine in operable association with a compressor, and an intake system is in fluid communication with the plurality of cylinders and the compressor. A first EGR cooler and a second EGR cooler are provided in fluid communication with the exhaust system through an inlet passage and the intake system through an outlet passage, respectively, between the plurality of cylinders. A transfer passage is provided between the two coolers, which comprises an EGR valve disposed therein to regulate the flow of fluid there through.
US7707998 discloses a method for operating an internal combustion engine, in which the exhaust gas generated in the internal combustion engine is returned by means of an exhaust gas recirculation device comprising at least two cooling devices, associated with each other by a bypass, and adapted to cool the exhaust gas in the device respective to the engine's load state. The

cooled exhaust gases are returned to the engine's cylinders selectively through multiple routes provided by the cooling devices and the bypasses, responsive to the certain load.
WO2010015940 discloses an exhaust heat recovery system that is adapted to accelerate an increase in temperature of a portion to be heated in a vehicle by utilizing heat from the exhaust gas of an internal combustion engine of the vehicle. The exhaust heat recovery system comprises a first and a second loop heat pipes; wherein the first loop heat pipe recovers exhaust heat downstream of a catalyst in an exhaust passage and exchanges heat with the catalyst to heat the catalyst, and the second loop heat pipe recovers the heat from the catalyst to heat an engine coolant which is delivered to the internal combustion engine. The first loop heat pipe and the second loop heat pipe are positioned in series with each other.
WO2009118622 discloses an exhaust gas recirculation device for an internal combustion engine which includes an EGR passage linking an exhaust passage with an intake passage of the internal combustion engine, and comprising an EGR valve for blocking the EGR passage when closed. An EGR catalyst is provided in the EGR passage between a connection portion and the EGR valve, wherein a control unit manipulates the exhaust gas recirculation by controlling the flow rate of exhaust gas there through. Further, EGR cooling devices can be provided positioned between the EGR valve and the EGR catalyst in the EGR passage.
WO2008059362 discloses an exhaust gas recirculation system for an internal combustion engine. The system comprises a turbocharger arranged in an

exhaust passage which contains an exhaust gas catalyst disposed therein, a compressor arranged in an intake passage, and an EGR unit operated at low-pressure and adapted to re-circulate a portion of exhaust gases through an EGR passage which is provided in communication with the exhaust passage and comprises an EGR cooler disposed therein to cool the exhaust gases. Further, a bypass unit controlled by a control unit allows bypassing the EGR cooler, and a catalyst activation-inactivation determination unit determines the state of the catalyst.
WO2007042181 discloses a device for re-circulating and cooling exhaust gas of an internal combustion engine, particularly a diesel engine of a motor vehicle. The internal combustion engine comprising an intake duct, an exhaust pipe, and an exhaust gas recirculation (EGR) pipe; wherein the exhaust pipe or EGR pipe comprise disposed therein at least one exhaust gas heat exchanger, an EGR valve, and an oxidation catalyst having an oxidation catalytic coating, being positioned upstream of the EGR valve, in the direction of flow of the exhaust gas.
WO2004044402 discloses a device for the thermal regulation of the pressurized intake air/exhaust gas mixture in an internal combustion engine, connected to an exhaust system fitted with a filter for removing particulate matter. The device comprises a principal heat exchanger having a first heat exchange means for exchanging heat between a heat transfer liquid and the intake air, and a second heat exchange means for exchanging heat between a heat transfer liquid and the re-circulated exhaust gas; wherein a circulation channel is provided for circulating the heat transfer liquid, common to both

heat exchange means, in heat exchange relation with the intake air and the re-circulated exhaust gas.
Although, ample work has been done on cooling the exhaust gases very little has been done to utilize this energy in heating the engine. Further, it has been proven that the engine emissions and friction are optimum under engine warm-up condition, i.e., typically when the engine coolant is at a temperature above 80 °C. Generally, the time span for heating the coolant to above 80 °C is high. A reduction in this time will enhance the engine operations and reduce engine friction, thereby, reducing fuel consumption and emissions. Rapid heating of the engine coolant will allow the combustion engine to heat up quickly; therefore, there is felt a need for a heat exchanger assembly, in communication with the internal combustion engine, which will help in rapid heating of the engine coolant to a desired temperature range.
Also, in some systems, heat from the exhaust gases is indirectly transferred to the engine coolant. This is done since over-heating and vaporization of the engine coolant is likely and not desirable. Also, regulating the heat transfer from the exhaust gases to the engine coolant, depending upon the requirement, is complex. Therefore, there is felt a need to design a simple exhaust gas heat recovery system which selectively extracts heat from the exhaust gases in the engine coolant, thereby providing rapid engine warm-up. Another drawback of the known exhaust gas heat recovery systems is that the exhaust gases condense during heat transfer causing corrosion of the exhaust gas cooler. Either cooling the exhaust gases above condensation point or coating the cooler surface with a corrosion-resistant material can

alleviate this problem. It is not feasible to completely prevent condensation of the exhaust gases; also, this causes wastage of heat in the exhaust gases. Further, adapting the exhaust gas cooler to be corrosion-resistant increases the cost of the heat recovery system. Therefore, there is felt a need for a simple and cost-effective exhaust gas heat recovery system which overcomes the above-mentioned drawback and thereby provides selective cooling of the exhaust gases depending upon their temperature.
OBJECTS
Some of the objects of the present disclosure which at-least one embodiment is able to satisfy, are described herein below:
It is an object of the present disclosure to ameliorate one or more problems of the prior art or to at least provide a useful alternative.
An object of the present disclosure is to provide a heat exchanger assembly for heating the engine coolant by extracting heat from re-circulated exhaust gases to provide rapid engine warm-up.
Another object of the present disclosure is to provide a heat exchanger assembly which selectively heats the engine coolant to prevent over-heating and vaporization.
Still another object of the present disclosure is to provide a heat exchanger assembly which optimally cools the re-circulated exhaust gases in up to two

cooling steps depending on their temperature and the engine loading conditions, thereby preventing condensation of the exhaust gases.
Yet another object of the present disclosure is to provide a heat exchanger assembly which is adapted to provide cooled and purified re-circulated exhaust gases to the internal combustion engine.
One more object of the present disclosure is to provide a heat exchanger assembly which is cost-effective, simple, and easy to design and manufacture.
Other objects and advantages of the present disclosure will be more apparent from the following description when read in conjunction with the accompanying figures, which are not intended to limit the scope of the present disclosure.
SUMMARY
A heat exchange assembly for facilitating heat exchange between hot exhaust gases entering an exhaust gas re-circulation (EGR) system of an internal combustion engine and engine coolant is disclosed in accordance with an embodiment of the present disclosure. The heat exchange assembly includes a first connecting passage, a heat exchanger device, an exhaust gas cooling device, a bypass passage, a second coolant passage, and an EGR valve. The first connecting passage receives hot exhaust gases leaving an exhaust manifold of the internal combustion engine. The heat exchanger device facilitates heat exchange between hot exhaust gases received therein

from the first connecting passage and a portion of the engine coolant received therein from a first coolant passage for extracting heat from the hot exhaust gases, utilizing heat extracted from the hot exhaust gases for heating the engine coolant, and releasing partially heat extracted exhaust gases and delivering heated engine coolant to a radiator of the internal combustion engine. The exhaust gas cooling device disposed downstream of the heat exchanger device and in fluid communication with the heat exchanger device via a second connecting passage, the exhaust gas cooling device receives the partially heat extracted exhaust gases leaving the heat exchanger device and brings the partially heat extracted exhaust gases in heat exchange relationship with the remaining portion of the engine coolant received therein from said first coolant passage for extracting residual heat from the partially heat extracted exhaust gases for heating the remaining portion of the engine coolant and re-circulating at least a portion of pre-heated engine coolant leaving the exhaust gas cooling device back to the first coolant passage. The by-pass passage directly connects the heat exchanger device to the EGR valve for selectively directing the partially heat extracted exhaust gases leaving the heat exchanger device directly to the internal combustion engine, thereby controlling the degree of cooling of the exhaust gases entering the internal combustion engine. The second coolant passage receives the heated engine coolant from the heat exchanger device and delivers the heated engine coolant to a radiator. The EGR valve is disposed upstream of the internal combustion engine and receives the heat extracted exhaust gases and direct the heat extracted exhaust gases to the internal combustion engine, thereby controlling the amount of re-circulated exhaust gases to the internal combustion engine.

Typically, the heat exchanger device is a tube in tube type heat exchanger device.
Further, the heat exchange assembly includes degassing means is disposed in the first coolant passage for separating gases from the engine coolant entering the heat exchanger device.
Typically, the exhaust gas cooling device is controlled by an engine control unit.
Preferably, the EGR valve is disposed downstream of the exhaust gas cooler and the bypass passage.
Typically, the heat exchanger assembly is disposed parallel to the engine radiator.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The disclosure will now be described with the help of the accompanying drawings, in which,
FIGURE 1 illustrates a schematic representation of a heat exchanger assembly in accordance with the present disclosure; and
FIGURE 2 illustrates another view of the heat exchanger assembly of the present disclosure.

DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The disclosure will now be described with reference to the accompanying drawings 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 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 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 present disclosure envisages a heat exchanger assembly includes a heat exchanger device and an exhaust gas cooler for providing direct heat transfer between hot exhaust gases and the engine coolant. The assembly is adapted to prevent over-heating and vaporization of the engine coolant by selective heat transfer. Further, the assembly is adapted to prevent condensation of the exhaust gases, at least in the heat exchanger device, by providing optimal exhaust gas cooling. The exhaust gas cooler may be provided with a corrosion-resistant material coating to protect from corrosion due to condensation. The hot exhaust gases are conveyed from the heat exchanger device to the exhaust gas cooler while the cold engine coolant is conveyed via the exhaust gas cooler to the heat exchanger device; where, depending upon the temperature of the hot exhaust gases and the engine load conditions, the exhaust gases leaving the heat exchanger device can be passed directly to the internal combustion engine or via the exhaust gas cooler, thereby, the engine coolant is optionally pre-heated in the exhaust gas cooler and subsequently further heated in the heat exchanger device. The heat exchanger assembly is partly controlled by the engine control unit (ECU) to manipulate the amount of exhaust gas recirculation, exhaust gas flow rate, and exhaust gas cooling.
The heat exchanger assembly of the present disclosure is illustrated in FIGURE 1 & 2, generally referenced by the numeral 100. The heat exchanger assembly 100 comprises a first connecting passage 102 which is operatively connected to an exhaust manifold (not shown in Figure) to

receive at least a portion of the hot exhaust gases. These hot exhaust gases are received in the heat exchanger device 104 from the first connecting passage 102, wherein the heat exchanger device 104 is located in series with the first connecting passage 102. The heat exchanger device 104 is adapted to circulate a preheated engine coolant in heat exchange relation to the hot exhaust gases so as to effect heat transfer between the two fluids and give a heated engine coolant and heat-extracted exhaust gases. The heat exchanger device 104 is positioned in series with an exhaust gas cooling device 108. The exhaust gas cooling device 108 receives at least a portion of cold engine coolant via a coolant supply line 116; the engine coolant is conveyed to the heat exchanger device 104 via a first coolant passage 110. The heat exchanger device 104, typically a tube-in-tube heat exchanger device, is adapted to provide 20 - 40 % of the total cooling of the exhaust gases in the assembly 100, i.e. above the condensation point of the exhaust gases. The heat exchanger device 104 is always in circuit and is not programmable by the ECU, also does not comprise any switch. An oxidation catalyst may be provided prior to the first connecting passage 102, wherein, the oxidation catalyst is generally a honeycomb structure covered with a layer of a chemical catalyst which contains small amounts of precious metal such as platinum, this metal exothermally interacts with and oxidizes pollutants in the exhaust stream (carbon monoxide and unburned hydrocarbons), thereby reducing poisonous emissions and elevating the exhaust gas temperature.
The heat-extracted exhaust gases from the heat exchanger device 104 are conveyed to the exhaust gas cooling device 108 through a second connecting passage 106 which operatively connects the exhaust gas cooling device 108 to the heat exchanger device 104. The exhaust gas cooling device 108 is

operatively connected to the engine control unit (not shown in Figure) which controls the operation of the exhaust gas cooling device 108. The exhaust gas cooling device 108 comprises the exhaust gas cooler (not shown in Figure), bypass means (not shown in Figure), and an EGR valve (not shown in Figure). The heat-extracted exhaust gases leaving the heat exchanger device 104 are selectively passed through the exhaust gas cooler, the bypass means, or both.
The cold engine coolant is received in the exhaust gas cooling device 108 at
the coolant supply line 116. This engine coolant passes through the exhaust
gas cooler into the first coolant passage 110, wherein, the exhaust gas cooler
is adapted to traverse the engine coolant in heat exchange relation to the
heat-extracted exhaust gases from the heat exchanger device 104, thereby
further cooling the exhaust gases and preheating the engine coolant. The
cooled exhaust gases are then received in the internal combustion engine via
the EGR valve as the re-circulated exhaust gases; the flow rate and quantity
of these gases are controlled by the EGR valve located subsequent to the
exhaust gas cooler, based on the engine load conditions. Alternatively, under
low engine load conditions, the bypass means is adapted to circumvent the
t exhaust gas cooler completely and direct the heat-extracted exhaust gases to
the internal combustion engine via the EGR valve. Additionally, only a
portion of the heat-extracted exhaust gases pass through the exhaust gas
cooler and the other portion flows through the bypass means. The operation
of the exhaust gas cooler and the bypass means is controlled by the ECU
based on the engine load conditions, to determine the exhaust gas cooling
and thereby the engine coolant heating. The operation of the EGR valve is
also controlled by the ECU to determine the flow rate and quantity of the re-

circulated exhaust gases to the internal combustion engine. The preheated engine coolant leaving the exhaust gas cooler, is transferred to the heat exchanger device 104 via the first coolant passage 110. The first coolant passage 110 comprises a degassing means 112 which is adapted to remove any trapped gases (air bubbles) from the engine coolant being conveyed to the heat exchanger device 104. In the heat exchanger device 104, the preheated engine coolant is heated by extracting heat from the hot exhaust gases. The heated engine coolant leaves the heat exchanger device 104 through the second coolant passage 114, wherein, the second coolant passage 114 is operatively-connected to the engine radiator at 118 to convey the heated engine coolant thereto. In the heat exchanger assembly 100, the first connecting passage 102, the heat exchanger device 104, the second connecting passage 106, and the exhaust gas cooling device 108 define the flow path of the exhaust gases from the exhaust manifold to the internal combustion engine; and the coolant supply line 116, the exhaust gas cooling device 108, the first coolant passage 110, the heat exchanger device 104, and the second coolant passage 114 define the flow path of the engine coolant from the coolant inlet to the engine radiator, wherein, these components are positioned parallel to the engine radiator.
The heat exchanger assembly 100 of the present disclosure is compact and can be conveniently arranged parallel to the engine radiator (not shown in the Figure). Further, the heat exchanger assembly 100 is adapted to extract heat from re-circulated exhaust gases to provide heated engine coolant.

TECHNICAL ADVANTAGES
A heat exchanger assembly for providing direct heat transfer between the hot exhaust gases and an engine coolant, as described in the present disclosure has several technical advantages including but not limited to the realization of:
• a heat exchanger assembly that selectively heats the engine coolant to prevent over-heating and vaporization thereof and effect rapid engine warm-up;
• a heat exchanger assembly that optimally cools the re-circulated exhaust gases in up to two cooling steps depending on their temperature and the engine loading conditions, thereby preventing condensation of the exhaust gases;
• a heat exchanger assembly that is cost-effective, simple, easy to design and manufacture, and is conveniently positioned parallel to the engine radiator; and
• a heat exchanger assembly that is partly controlled by the engine control unit which based on the engine loading conditions manipulates the amount of exhaust gas recirculation and the exhaust gas cooling.
Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

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 invention 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 invention. 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 invention 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 specific features of the preferred embodiment, it will be appreciated that many additional features can be added and that many changes can be made in the preferred embodiment without departing from the principles of the invention. These and other changes in the preferred embodiment of the invention 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 invention and not as a limitation.

We Claim:
1. A heat exchange assembly for facilitating heat exchange between hot exhaust gases entering an exhaust gas re-circulation (EGR) system of an internal combustion engine and engine coolant, said heat exchange assembly comprising:
• a first connecting passage adapted to receive hot exhaust gases leaving an exhaust manifold of the internal combustion engine;
• a heat exchanger device adapted to facilitate heat exchange between hot exhaust gases received therein from said first connecting passage and a portion of the engine coolant received therein from a first coolant passage for extracting heat from the hot exhaust gases, utilizing heat extracted from the hot exhaust gases for heating the engine coolant, and releasing partially heat extracted exhaust gases and delivering heated engine coolant to a radiator of the internal combustion engine;
• an exhaust gas cooling device disposed downstream of said heat exchanger device and in fluid communication with said heat exchanger device via a second connecting passage, said exhaust gas cooling device adapted to receive said partially heat extracted exhaust gases leaving said heat exchanger device and brings in heat exchange relationship with the remaining portion of said engine coolant received therein from said first coolant passage for extracting residual heat from the partially heat extracted exhaust gases for heating said remaining portion of said engine coolant and re-circulating at least a portion of pre-

heated engine coolant leaving said exhaust gas cooling device back to said first coolant passage;
• a by-pass passage adapted to directly connect said heat exchanger device to said EGR valve for selectively directing said partially heat extracted exhaust gases leaving said heat exchanger device directly to the internal combustion engine, thereby controlling the degree of cooling of the hot exhaust gases entering the internal combustion engine;
• a second coolant passage adapted to receive said heated engine coolant from said heat exchanger device and deliver said heated engine coolant to said radiator; and
• an EGR valve disposed upstream of the internal combustion engine, said EGR valve adapted to receive said heat extracted exhaust gases and direct the heat extracted exhaust gases to the internal combustion engine, thereby controlling the amount of re-circulated exhaust gases to the internal combustion engine.
2. A heat exchange assembly of claim 1, wherein said heat exchanger device is a tube in tube type heat exchanger device.
:3. A heat exchange assembly of claim 1, further comprising
degassing means disposed in said first coolant passage for separating gases from the engine coolant entering said heat exchanger device.
4. A heat exchange assembly of claim 1, wherein said exhaust gas
pooling device is controlled by an engine control unit.

.5. A heat exchange assembly of claim 1, wherein said EGR valve
is disposed downstream of said exhaust gas cooler and said bypass passage.
6. A heat exchange assembly of claim 1 is disposed parallel to
said engine radiator.