FORM 2
The Patent Act 1970
(39 of 1970)
AND
The Patent Rules, 2005
COMPLETE SPECIFICATION (SEE SECTION 10 AND RULE 13)
TITLE OF THE INVENTION
A DOUBLE-WALLED EXHAUST SYSTEM FOR A VEHICLE
APPLICANT(S)
TATA MOTORS LIMITED
An Indian Company
Bombay House, 24 Homi Mody Street,
Hutatma Chowk, Mumbai - 400 001,
Maharashtra, India.
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF THE INVENTION
[0001] The present disclosure relates to a double-walled exhaust system for a vehicle, and more particularly relates to the double-walled exhaust system with a double-walled exhaust pipe to control and maintain temperature in a diesel particulate filter (DPF).
BACKGROUND OF THE INVENTION
[0002] Internal combustion engines of an after treatment system generate heat during operation that is released into the environment through exhaust gas emissions. Modern emission controls systems may utilize energy, in the form of heat from the exhaust gas, to operate various components, for example, Diesel Particulate Filters (DPF). The DPF needs to be operated in a particular temperature band to efficiently burn a particulate matter. So it is important to reduce or avoid temperature drop between the engine and the DPF while operating the engine in cold or heavy rain regions or while operating the engine with a low engine speed and low load etc. Also while operating the engine at a high engine speed and at a high load, a temperature of the DPF may go above the requirement. This effect performance and deteriorate life of the after-treatment system. So it is also important to reject this undesirable heat to atmosphere before reaching to the DPF.
[0003] Different systems are proposed to address the problems mentioned above. In one example of the conventional system in which heat retention and rejection depends on a reaction that occurs internally to the DPF and burns particulates that have accumulated therein. Some engines incorporate thermal shielding on their exhaust systems to contain exhaust heat and make it available for emissions components. However, conventional system fails to provide

address the above mentioned problems. Accordingly, there is a need of an efficient exhaust system to control and maintain temperature in the DPF.
OBJECT OF THE INVENTION
[0004] The principal object of the embodiments herein is to provide a double-walled exhaust system with a double-walled exhaust pipe for a vehicle to control and maintain temperature in a diesel particulate filter (DPF). This is useful for retention and rejection of heat in exhaust flow of an internal combustion engine thereby enhancing a performance of exhaust pollution control devices.
[0005] Another object of the embodiments herein is to determine that a temperature of the DPF is less than a threshold and draw air from a double-walled exhaust pipe to stop or reduce heat rejection to atmosphere.
[0006] Yet another object of the embodiments herein is to determine that a temperature of the DPF is more than the threshold and allow atmospheric air to enter into the double-walled exhaust pipe to start heat rejection to the atmosphere.
SUMMARY OF THE INVENTION
[0007] In one aspect object is satisfied by providing a double-walled exhaust system for a vehicle. The an double-walled exhaust system comprising an engine, a vacuum pump connected to the engine, a diesel particulate filter (DPF), a double-walled exhaust pipe connected between the engine and the DPF, a first value and a second value connected to the double-walled exhaust pipe, a vacuum switch connected to the first value and the second value, a temperature sensor coupled to the DPF, and electronic control unit (ECU) connected to the

vacuum switch and the DPF. The temperature sensor configured to sense a temperature of the DPF. The ECU configured to trigger the vacuum switch to control an air flow of the double-walled exhaust pipe through the first value and the second value based on the sensed temperature of the DPF.
[0008] In an embodiment, control the air flow of the double-walled exhaust pipe through the first value and the second value based on the sensed temperature of the DPF comprises detecting by the ECU that the temperature of the DPF is less than a threshold, triggering by the ECU the vacuum switch to open the first valve and closes the second valve, and drawing by the vacuum pump air from the double-walled exhaust pipe through the first value to stop or reduce heat rejection to atmosphere.
[0009] In an embodiment, the heat rejection to the atmosphere is stopped or reduced continuously until the temperature of the DPF is more than the threshold.
[0010] In an embodiment, control the air flow of the double-walled exhaust pipe through the first value and the second value based on the sensed temperature of the DPF comprises detecting by the ECU that the temperature of the DPF is more than a threshold, triggering by the ECU the vacuum switch to closes the first valve and opens the second valve, and allowing atmospheric air to enter into the double-walled exhaust pipe by the second the value to start heat rejection to atmosphere.
[0011] In an embodiment, the heat rejection to the atmosphere is continued until the temperature of the DPF is less than the threshold.
[0012] In an embodiment, a vacuum line is connected to the vacuum pump and the first value.

[0013] Another embodiments described herein provide a method implemented by the double-walled exhaust system. The method comprising sensing a temperature of the DPF and determining whether temperature is less than or more than a threshold. Further, the method inclines drawing air from the double-walled exhaust pipe to stop or reduce heat rejection to atmosphere in response to determining that the temperature of the DPF is less than the threshold. The heat rejection to the atmosphere is stopped or reduced continuously until the temperature of the DPF is more than the threshold. Furthermore, the method includes allowing atmospheric air to enter into the double-walled exhaust pipe to start heat rejection to the atmosphere in response to determining that the temperature of the DPF is more than the threshold. The heat rejection to the atmosphere is continued until the temperature of the DPF is less than the threshold.
[0014] These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating preferred embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.
BRIEF DESCRIPTION OF DRAWINGS
[0015] This connector is illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which:

[0016] FIGS. 1 is a block diagram illustrating a double-walled exhaust system, according to an embodiment as disclosed herein; and
[0017] FIGS. 2 is a flow chart illustrating a method implemented by the double-walled exhaust system, according to an embodiment as disclosed herein.
DETAILED DESCRIPTION OF THE INVENTION
[0018] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. Also, the various embodiments described herein are not necessarily mutually exclusive, as some embodiments can be combined with one or more other embodiments to form new embodiments. The term “or” as used herein, refers to a non-exclusive or, unless otherwise indicated. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein can be practiced and to further enable those skilled in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
[0019] The accompanying drawings are used to help easily understand various technical features and it should be understood that the embodiments presented herein are not limited by the accompanying drawings. As such, the present disclosure should be construed to extend to any alterations, equivalents and substitutes in addition to those which are particularly set out in the accompanying drawings. Although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are generally only used to distinguish one element from another.

[0020] Referring now to the drawings, and more particularly to FIGS. 1-2, there are shown preferred embodiments.
[0021] FIGS. 1 is a block diagram illustrating a double-walled exhaust system, according to an embodiment as disclosed herein. The double-walled exhaust system for a vehicle. The double-walled exhaust system comprising an engine (1), a vacuum pump (2), a diesel particulate filter (DPF) (3), a double-walled exhaust pipe (4), a first valve (5), a second valve (6), a vacuum switch (7), a temperature sensor (8), an electronic control unit (ECU) (9), and a vacuum line (10).
[0022] The vacuum pump (2) is mounted on the engine (1). The double-walled exhaust pipe (4) is connected between the engine (1) and the DPF (3). The first valve (5) and the second valve (6) are connected to the double-walled exhaust pipe (4). The vacuum switch (7) is connected to the first valve (5) and the second valve (6). The temperature sensor (8) is coupled to the DPF (3) and is configured to sense a temperature of the DPF (3). The ECU (9) is connected to the vacuum switch (7) and the DPF (3). The ECU (9) is configured to trigger the vacuum switch (7) to control an air flow of the double-walled exhaust pipe (4) through the first valve (5) and the second valve (6) based on the sensed temperature of the DPF (3). The vacuum line (10) is connected to the vacuum pump (2) and the first valve (5). All the components are electrically connected using electrical connections (11).
[0023] Generically, the fuel is burned in the engine (1) and exhaust gases are produced which are eliminated into the atmosphere. The gases from the engine (1) comprises particulate matter which are filtered to avoid environmental pollution. The filtration is performed in the DPF (3) which also further burns the particulate matter within a temperature of 250 to 600 degree Celsius. This

temperature is maintained either due to the heat in the exhaust gases from the engine (1) itself which is called passive regeneration or by burning fuel which is called active regeneration. In any case, for efficient working of the exhaust system, the exhaust pollutant or particulate matter must be burned in the DPF (3) and for that the required temperate should be maintained.
[0024] In an embodiment, in order to control the air flow of the double-walled exhaust pipe (4) through the first valve (5) and the second valve (6) based on the sensed temperature of the DPF (3), the ECU (9) detects that the temperature of the DPF (3) is less than a threshold and triggers the vacuum switch (7) to open the first valve (5) and closes the second valve (6). This allows the vacuum pump (2) to draw air from the double-walled exhaust pipe (4) through the first valve (5) to stop or reduce heat rejection to atmosphere. As the vacuum is created between the double walled pipes (4), it will stop or reduce the heat rejection to the atmosphere. The heat rejection to the atmosphere is stopped or reduced continuously until the temperature of the DPF (3) is more than the threshold.
[0025] In an embodiment, in order to control the air flow of the double-walled exhaust pipe (4) through the first valve (5) and the second valve (6) based on the sensed temperature of the DPF (3), the ECU (9) detects that the temperature of the DPF (3) is more than a threshold and triggers the vacuum switch (7) to close the first valve (5) and opens the second valve (6). This allows atmospheric air to enter into the double-walled exhaust pipe (4) by the second the valve (6) to start heat rejection to atmosphere. As the vacuum in the double wall vanishes, it will start heat rejection to the atmosphere and will keep rejecting the heat until the temperature of the DPF (3) is less than the threshold.
[0026] FIGS. 2 is a flow chart illustrating a method implemented by the double-walled exhaust system, according to an embodiment as disclosed herein.

At step 202, the method comprises sensing a temperature of the DPF (3). The temperature at the DPF (3) is sensed using the temperature sensor (8) connected to the DPF (3). At step 204, the method comprises determining whether temperature is less than or more than a threshold by the ECU (9).
[0027] In response to determining that the temperature of the DPF (3) is less than the threshold, at step 206, the method includes drawing air from the double-walled exhaust pipe (4) to stop or reduce heat rejection to atmosphere. At this point, the ECU (9) triggers the vacuum switch (7) to open the first valve (5) and closes the second valve (6) thereby allowing the vacuum pump (2) to draw air from the double-walled exhaust pipe (4) through the first valve (5) to stop or reduce heat rejection to atmosphere. This will continue until the temperature of the DPF (3) is more than the threshold.
[0028] Further, in response to determining that the temperature of the DPF (3) is more than the threshold, at step 208, the method includes allowing atmospheric air to enter into the double-walled exhaust pipe (4) to start heat rejection to the atmosphere. At this point, the ECU (9) triggers the vacuum switch (7) to close the first valve (5) and opens the second valve (6) thereby allowing the atmospheric air to enter into the double-walled exhaust pipe (4) by the second the valve (6). As the vacuum in the double wall vanishes, it will start heat rejection to the atmosphere. This heat rejection is continued until the temperature of the DPF (3) is less than the threshold.
[0029] Unlike the conventional system, the proposed double-walled exhaust system is used for heat rejection and retention in exhaust flow of any internal combustion engine.
[0030] 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.

We Claim:
1. A double-walled exhaust system for a vehicle, comprising:
an engine (1);
a vacuum pump (2) connected to the engine (1);
a diesel particulate filter (DPF) (3);
a double-walled exhaust pipe (4) connected between the engine (1) and the DPF (3);
a first valve (5) and a second valve (6) connected to the double-walled exhaust pipe (4);
a vacuum switch (7) connected to the first valve (5) and the second valve (6);
a temperature sensor (8), coupled to the DPF (3), configured to sense a temperature of the DPF (3); and
an electronic control unit (ECU) (9), connected to the vacuum switch (7) and the DPF (3) configured to trigger the vacuum switch (7) to control an air flow of the double-walled exhaust pipe (4) through the first valve (5) and the second valve (6) based on the sensed temperature of the DPF (3).
2. The double-walled exhaust system as claimed in claim 1, wherein control the air
flow of the double-walled exhaust pipe (4) through the first valve (5) and the
second valve (6) based on the sensed temperature of the DPF (3) comprises:
detecting, by the ECU (9), that the temperature of the DPF (3) is less than a threshold;
triggering, by the ECU (9), the vacuum switch (7) to open the first valve (5) and closes the second valve (6); and
drawing, by the vacuum pump (2), air from the double-walled exhaust pipe (4) through the first valve (5) to stop or reduce heat rejection to atmosphere.

3. The double-walled exhaust system as claimed in claim 2, wherein the heat rejection to the atmosphere is stopped or reduced continuously until the temperature of the DPF (3) is more than the threshold.
4. The double-walled exhaust system as claimed in claim 1, wherein control the air flow of the double-walled exhaust pipe (4) through the first valve (5) and the second valve (6) based on the sensed temperature of the DPF (3) comprises:
detecting, by the ECU (9), that the temperature of the DPF (3) is more than a threshold;
triggering, by the ECU (9), the vacuum switch (7) to closes the first valve (5) and opens the second valve (6); and
allowing atmospheric air to enter into the double-walled exhaust pipe (4) by the second the valve (6) to start heat rejection to atmosphere.
5. The double-walled exhaust system as claimed in claim 4, wherein the heat rejection to the atmosphere is continued until the temperature of the DPF (3) is less than the threshold.
6. The double-walled exhaust system as claimed in claim 1, wherein a vacuum line (10) is connected to the vacuum pump (2) and the first valve (5).
7. A method implemented by a double-walled exhaust system comprising a double-walled exhaust pipe (4) connected between an engine (1) and a diesel particulate filter (DPF) (3), comprising:
sensing a temperature of the DPF (3);
determining whether temperature is less than or more than a threshold; and
performing one of:
drawing air from the double-walled exhaust pipe (4) to stop or reduce heat rejection to atmosphere in response to determining that the temperature of the DPF (3) is less than the threshold, and

allowing atmospheric air to enter into the double-walled exhaust pipe (4) to start heat rejection to the atmosphere in response to determining that the temperature of the DPF (3) is more than the threshold.
8. The method as claimed in claim 7, wherein the heat rejection to the atmosphere is stopped or reduced continuously until the temperature of the DPF (3) is more than the threshold.
9. The method as claimed in claim 7, wherein the heat rejection to the atmosphere is continued until the temperature of the DPF (3) is less than the threshold.