WO2024009161A1

WO2024009161A1 - A method for pre-heating an exhaust after treatment unit and a system thereof

Info

Publication number: WO2024009161A1
Application number: PCT/IB2023/056195
Authority: WO
Inventors: Vivek M KOLHE; Chinmayananda Khandai; Girish Anil Kothari
Original assignee: Tata Motors Limited
Priority date: 2022-07-05
Filing date: 2023-06-15
Publication date: 2024-01-11

Abstract

A method for pre-heating an exhaust gas after treatment unit (100) is disclosed. The method includes aspect of receiving a signal corresponding to a torque of an engine (2) and a signal corresponding to a temperature of a plurality of emission reduction units (10) by a control unit (4). The control unit (4) compares the engine torque with a pre-determined threshold torque and a maximum temperature from the plurality of emission reduction units (10) is compared with a pre-determined first threshold temperature. The bypass valve (7) is actuated when the maximum temperature is lesser than the pre-determined first threshold temperature and when the engine torque is lesser than the pre-determined threshold torque. Actuation of the bypass valve (7) bypasses the compressed air into an intake manifold (1) of the engine (2) for pre-heating the plurality of emission reduction units (10) and to increase the temperature of exhaust gases.

Description

A METHOD FOR PRE-HEATING AN EXHAUST AFTER TREATMENT UNIT AND A SYSTEM THEREOF

TECHNICAE FIEED

Present disclosure generally relates to a field of automobiles. Particularly, but not exclusively, the present disclosure relates to an exhaust after-treatment unit of a vehicle. Further, embodiments of the present disclosure describe a system for pre-heating the exhaust after- treatment unit.

BACKGROUND OF THE INVENTION

Internal combustion engines emit exhaust gases into atmosphere that may be harmful to environment and is one of the major causes for global warming. To reduce these emissions from the vehicles, various systems have been employed in the engine and exhaust system of the vehicles. Vehicles are provided with emission reduction units which are employed in the engine and the exhaust systems of the vehicles to limit the discharge of noxious gases from such components of the vehicles. Exhaust pipe discharges burnt and unburnt hydrocarbons, carbon monoxide, oxides of nitrogen, Sulphur, and traces of various acids etc.

Vehicles are generally employed with exhaust gas after treatment units for controlling the emission. The exhaust gas after treatment units includes emission reduction units such as oxidation catalysts, lean NOx trap, particulate filters, and selective catalytic reductor (SCR) system. The above-described emission reduction units are configured to absorb or reduce the quantity of harmful gases such as burnt and unbumt hydrocarbons, carbon monoxide, oxides of nitrogen, Sulphur, and traces of various acids etc. which are discharged by the exhaust pipe. The emission reduction units are configured to reduce the quantity of harmful gases in the exhaust gases below a prescribed limit and then subsequently released into the atmosphere.

The above-described emission reduction units operate at an optimal stage when the exhaust gas temperature reaches a pre-determined level. If the exhaust gas temperature is below a predetermined level, the emission reduction units do not operate at the required efficiency and the emission requirements are not met. Therefore, the exhaust gas after treatment units is designed to achieve this pre-determined level of operating temperature as quickly as possible. Consequently, conventional strategies such as post injection, injection timing retardation, intake air throttling etc. have been adapted to quickly warm up the exhaust gas after treatment units and maintain necessary temperature of the exhaust gas. However, these conventional methods consume excessive fuel and result in reduction in efficiency.

The present disclosure is directed to overcome one or more limitations stated above or any other limitations associated with the conventional configuration of intake ports.

SUMMARY OF THE DISCLOSURE

One or more shortcomings of the conventional system or method are overcome, and additional advantages are provided through the provision of the method as claimed in the present disclosure.

Additional features and advantages are realized through the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed disclosure.

In a non-limiting embodiment of the disclosure, a method for pre-heating an exhaust gas after treatment unit is disclosed. The method includes aspects of receiving by a control unit, a signal corresponding to a torque of an engine from an engine torque sensor. The control unit also receives a signal corresponding to a temperature of a plurality of emission reduction units from a first temperature sensor. The control unit further compares the engine torque with a predetermined threshold torque and the control unit also compares a maximum temperature from the plurality of emission reduction units with a pre-determined first threshold temperature. A bypass valve is actuated by a signal from the control unit, when the maximum temperature is lesser than the pre-determined first threshold temperature and when the engine torque is lesser than the pre-determined threshold torque. Further, the selective actuation of the bypass valve, bypasses the compressed air into an intake manifold of the engine for pre-heating the plurality of emission reduction units to increase the temperature of exhaust gases in the exhaust gas after treatment unit.

In an embodiment of the disclosure, the control unit receives a signal by a second sensor corresponding to an intake air temperature.

In an embodiment of the disclosure, the control unit compares the determined intake air temperature with a pre-determined threshold intake air temperature. In an embodiment of the disclosure, the bypass valve is opened when the intake air temperature is greater than the pre-determined threshold intake air temperature.

In an embodiment of the disclosure, the bypass valve is opened by a signal from the control unit when at least one of the intake air temperatures is greater than the pre-determined threshold intake air temperature or when the determined maximum temperature is lesser than the predetermined first threshold temperature and when the engine torque is lesser than the predetermined threshold torque.

In an embodiment of the disclosure, determining the temperature of the plurality of emission reduction units in the exhaust gas after treatment unit includes determining temperatures of diesel oxidation catalysts, lean NOx trap, diesel particulate filter and selective catalytic reduction unit.

In an embodiment of the disclosure, the control unit compares the temperature of the plurality of emission reduction units for determining the maximum temperature of one of the pluralities of emission reduction units.

In a non-limiting embodiment of the disclosure, a system for pre-heating an exhaust gas after treatment unit is disclosed. The system includes a turbocharger configured to receive exhaust gases from an exhaust manifold where, a turbine of the turbocharger is fluidly coupled to the plurality of emission reduction units in the exhaust gas after treatment unit. A bypass valve is fluidly coupled to a compressor and is configured to receive compressed air from the compressor. Further, a control unit is communicatively coupled to at least one temperature sensor (5, 9) in the exhaust gas after treatment unit for determining the temperature of the plurality of emission reduction units and for determining the temperature of the intake air. The control unit selectively actuates the bypass valve between an open position and a closed position for bypassing the compressed air to the intake manifold of the engine and increases the temperature of exhaust gases from the engine for heating the plurality of emission reduction units in the exhaust gas after treatment unit.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description. BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES

The novel features and characteristic of the disclosure are set forth in the appended claims. The disclosure itself, however, as well as a preferred mode of use, further objectives, and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying figures. One or more embodiments are now described, by way of example only, with reference to the accompanying figures wherein like reference numerals represent like elements and in which:

Figure 1 illustrates a system for pre-heating an exhaust gas after treatment unit, in accordance with an embodiment of the disclosure.

Figure 2 illustrates a flowchart of a method for pre-heating the exhaust gas after treatment unit, in accordance with an embodiment of the disclosure.

The figure depicts embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the method for pre-heating an exhaust gas after treatment unit without departing from the principles of the disclosure described herein.

DETAILED DESCRIPTION

The foregoing has broadly outlined the features and technical advantages of the present disclosure in order that the description of the disclosure that follows may be better understood. Additional features and advantages of the disclosure will be described hereinafter which form the subject of the disclosure. It should be appreciated by those skilled in the art that the conception and specific embodiments disclosed may be readily utilized as a basis for modifying or designing other system for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the disclosure. The novel features which are believed to be characteristic of the disclosure, as to its organization, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure. In the present document, the word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any embodiment or implementation of the present subject matter described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

While the disclosure is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and will be described below. It should be understood, however that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the scope of the disclosure.

The terms “comprises”, “comprising”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a system that comprises a list of components does not include only those components but may include other components not expressly listed or inherent to such mechanism. In other words, one or more elements in the device or mechanism proceeded by “comprises... a” does not, without more constraints, preclude the existence of other elements or additional elements in the mechanism.

The following paragraphs describe the present disclosure with reference to Figs. 1 to 4. In the figures, the same element or elements which have same functions are indicated by the same reference signs. It is to be noted that, the vehicle including powertrain and the chassis is not illustrated in the figures for the purpose of simplicity. One skilled in the art would appreciate the method for pre-heating the exhaust gas after treatment unit as disclosed in the present disclosure that may be used in any vehicles that employs/includes exhaust systems, where such vehicles may include, but not be limited to, light duty vehicles, passenger vehicles, commercial vehicles, and the like.

Figure 1 illustrates a system (200) for pre-heating an exhaust gas after treatment unit (100). An engine (2) of a vehicle may be fluidly connected to an intake manifold (1). The intake manifold may herein be configured to direct an incoming stream of air into the engine. Combustion of fuel and the incoming stream of air may occur in the engine and exhaust gases are generated as a result of the combustion process. The engine (2) may be coupled to a torque sensor (2a) to measure the torque generated by the engine. The system (200) may include a control unit (4) that is communicatively coupled to the torque sensor (2a). The control unit (4) may be configured to receive signals from the torque sensor (2a) which corresponds to the torque generate by the engine (2) in real time. Further, the engine (2) may be fluidly coupled to an exhaust manifold (3). The exhaust manifold (3) may be configured to receive the exhaust gases from the engine (2). A turbocharger (8) which includes a compressor (8a), and a turbine (8b) may be fluidly coupled to the exhaust manifold (3). A turbine (8b) of the turbocharger (8) may be fluidly coupled to the exhaust manifold (3) and the exhaust gases may flow from the exhaust manifold (3) into the turbine (8b) to rotate the turbine (8b). The turbine (8b) may be coupled to the compressor (8a) by a shaft and the rotation of the turbine (8b) rotates the compressor (8a). The compressor (8a) of the turbocharger (8) may draw in air from the atmosphere. The compressor (8a) may further compressor air to a denser state. Consequently, during this process the temperature of the compressed air increases as the air is compressed to a denser state. This compressed air may herein be referred to as the intake air. The spent exhaust gases that rotate the turbine (8b) may exit the turbine (8b) and are directed into the exhaust gas after treatment unit (100). The exhaust gas after treatment unit (100) may further include a plurality of emission reduction units (10) [hereinafter referred to as the emission reduction units]. The emission reduction units (10) may reduce the quantity of harmful gases in the exhaust gases to the prescribed levels. The harmful gases in the exhaust gases may include but not be limited to unbumt hydrocarbons, carbon monoxide, oxides of nitrogen, Sulphur, traces of various acids etc. The exhaust gas from the turbine (8b) is subjected to reduction of harmful gases by the emission reduction units (10) and the exhaust gases are subsequently released into the atmosphere.

The exhaust gas after treatment unit (100) may include at least one first temperature sensor (9). The at least one first temperature sensor (9) [hereinafter referred to as the first temperature sensor] may be configured to detect the temperature of each of the plurality of emission reduction unit (10). The first temperature sensor (9) may be connected to the control unit (4) and the control unit (4) may be configured to receive a signal from the first temperature sensor

(9) which corresponds to the temperature of each of the plurality of emission reduction units

(10) in the exhaust gas after treatment unit (100). The first temperature sensor (9) must not be herein limited to a single temperature sensor and the first temperature sensor (9) may in an embodiment be considered as a combination of plurality of temperature sensors where, each of the plurality of temperature sensor may be individually configured to detect the temperature of each of the plurality of emission reduction units (10). In an embodiment, the first temperature sensor (9) may be configured to detect the temperatures of the exhaust gases that exit each of the plurality of emission reduction unit (10). The emission reduction unit (10) may include a diesel oxidation catalyst (DOC) [10a]. The diesel oxidation catalyst (10a) [hereinafter referred to as DOC] may include a precious metal which converts both hydrocarbon and carbon monoxide gaseous pollutants by catalyzing the oxidation of these pollutants to carbon dioxide and water. The DOC unit (10a) may be placed in the exhaust flow path to treat the exhaust gases before it is vented to the atmosphere. The emission reduction unit (10) may also include a Lean NOx Trap (10b) [hereinafter referred to as LNT] system to remove the nitrogen oxide in the exhaust gas. The LNT unit (10b) operates by storing NOx during normal lean operation. The emission reduction unit (10) further includes a diesel particulate filter (10c) (hereinafter referred to as DPF). The DPF unit (10c) may trap particulates including but not limited to soot and ash which may be generated during the combustion of hydrocarbon fuels such as diesel fuel. The DPF unit (10c) may include a ceramic filter or metallic filter that is positioned within a filter body and is adapted to trap particulates that are carried in the exhaust stream. The emission reduction unit (10) may include a selective catalytic reduction unit (lOd) [hereinafter referred to as the SCR]. The SCR unit (lOd) is installed to reduce harmful Nitrous Oxide (NOx) emissions. SCR unit (lOd) involves the aspect of injecting urea into the exhaust stream of a diesel engine through a catalyst. The urea sets off a chemical reaction which converts the NOx into Nitrogen, water, and small amounts of carbon dioxide. The above-described emission reduction units (10) must not be considered as a limitation and other emission reduction units (10) may also be employed herein for reducing the quantity of harmful gases in the exhaust gas.

Further, the compressor (8a) of the turbocharger (8) may be fluidly coupled to a bypass valve (7). The bypass valve (7) may herein be defined with one inlet and two outlets. The inlet of the bypass valve (7) may be configured to receive the intake air from the compressor (8a). The bypass valve (7) may be connected to the control unit (4). The control unit (4) may selectively transmit signal to the bypass valve (7) for directing the intake air from the inlet of the bypass valve (7) into one of the two outlets of the bypass valve (7). Further, one of the outlets of the bypass valve (7) may be fluidly coupled to a first path (11) whereas the other outlet of the bypass valve (7) is fluidly coupled to a second path (12). The first path (11) may include an intercooler (6). When the intake air from the bypass valve (7) is directed to flow through the first path (11), the intercooler (6) is configured to receive the intake air from the bypass valve (7). The intercooler (6) may herein be configured to reduce the temperature of the intake air/cool the intake air and thereby increase the density of the intake air. The cooled and dense intake air that exits the intercooler (6) may further flow through the first path (11) into the intake manifold (1). Further, the bypass valve (7) may also be configured by the control unit (4) to direct the intake air from the compressor (8a) into the second path (12). The second path (12) does not include the intercooler (6) or other components. The second path (12) extends between the intake manifold (1) and the bypass valve (7). The second path (12) enables the direct flow of the intake air from the compressor (8a) into the intake manifold (1). When the intake air is directed into the second path (12) by the bypass valve (7), the intake air directly flows into the intake manifold (1) and bypasses the intercooler (6). The temperature of the intake air that directly flows into the intake manifold (1) through the second path (12) is greater than the temperature of the intake air that is cooled by the intercooler (6) in the first path (11).

The system (200) may also include a second temperature sensor (5). The second temperature sensor (5) in a preferable embodiment may be positioned between an outlet of the compressor (8a) and the inlet of the bypass valve (7). The second temperature sensor (5) may be configured to detect the temperature of the intake air that exits that compressor (8a) and the positioning of the second temperature sensor (5) must not be considered as a limitation. The control unit (4) is herein configured to receive a signal from the second temperature sensor (5) which corresponds to the temperature of the intake air form the compressor (8a).

In an embodiment, the control unit (4) may include a processing unit and the processing unit may be configured to compare the determined parameters with pre-determined threshold parameters.

Figure 2 illustrates a flowchart of a method for pre-heating the exhaust gas after treatment unit (100). The method of operating the bypass valve (7) by the control unit (4) is based on three different conditions which is explained in detail below. The first condition is with regards to the engine torque of the vehicle. The control unit (4) may receive a signal from the torque sensor (2a) that is associated with the engine (2). The control unit (4) may receive a signal that corresponds to the torque generated by the engine in real time. The processing unit of the control unit (4) may compare the engine torque with a pre-determined threshold torque. If the engine torque is higher than the pre-determined threshold torque, the control unit (4) interprets that the temperature of the exhaust gases may be sufficient for pre-heating the emission reduction units (10) in the exhaust gas after treatment unit (100). However, if the engine torque is lower than the pre-determined threshold torque, the control unit (4) interprets that the temperature of the exhaust gases is low and is not sufficient for pre-heating the emission reduction units (10) in the exhaust gas after treatment unit (100). The first condition may herein be rendered as satisfied if the engine torque is found to be lower than the pre-determined threshold torque. In an embodiment, the pre-determined threshold temperature may be set by multiple trials. For instance, the engine (2) may be operated at one particular torque and the temperature of exhaust gases may subsequently be measured. Further, the pre-heating of the emission reduction units (10) may also be measured at that given torque of the engine (2). Multiple such trails may be conducted and the value/torque at which the exhaust gases heat the emission reduction units (10) to the required level may be recorded and set as the predetermined threshold torque.

The second condition may include the aspect of the control unit (4) receiving signals from the first temperature sensor (9) for determining the temperature of each of the plurality of emission reduction units (10). The first temperature sensor (9) may herein be multiple sensors that are coupled with the DOC unit (10a), the LNT unit (10b), the DPF unit (10c) and the SCR unit (lOd). The control unit (4) may receive the signals from the first temperature sensor (9) and the control unit (4) may determine the temperature of the DOC unit (10a), the LNT unit (10b), the DPF unit (10c) and the SCR unit (lOd). The processing unit of the control unit (4) may further compare the temperature of each of the plurality of emission reduction units (10). The processing unit of the control unit (4) may compare the determined temperatures of the DOC unit (10a), the LNT unit (10b), the DPF unit (10c) and the SCR unit (lOd). The processing unit of the control unit (4) may further determine the maximum temperature of the DOC unit (10a), the LNT unit (10b), the DPF unit (10c) and the SCR unit (lOd). The processing unit may determine the maximum temperature based on the comparison of the temperature of each of the DOC unit (10a), the LNT unit (10b), the DPF unit (10c) and the SCR unit (lOd). Further, the determined maximum temperature may further be compared with a pre-determined first threshold temperature. If the maximum temperature is found to be higher than the predetermined first threshold temperature, the control unit (4) interprets that the temperature of the exhaust gases may be sufficient for pre-heating the emission reduction units (10) in the exhaust gas after treatment unit (100). However, if the maximum temperature is found to be lesser than the pre-determined first threshold temperature, the control unit (4) interprets that the temperature of the exhaust gases is low and is not sufficient for pre-heating the emission reduction units (10) in the exhaust gas after treatment unit (100). The second condition may herein be rendered as satisfied if the maximum temperature is found to be lesser than the predetermined first threshold temperature. The control unit (4) is also configured to receive a signal from the second temperature sensor (5) in the third condition. The control unit (4) may receive the signal from the second temperature sensor (5) and the signal may correspond to the intake air temperature or the temperature of the air that exits the compressor (8a) in the turbocharger (8). The processing unit of the control unit (4) may be configured to compare the determined intake air temperature with a pre-determined threshold intake air temperature. If the intake air temperature is found to be higher than the pre-determined threshold intake air temperature, the control unit (4) interprets that the temperature of the exhaust gases may be sufficient for pre-heating the emission reduction units (10) in the exhaust gas after treatment unit (100). However, if the intake air temperature is found to be lesser than the pre-determined threshold intake air temperature, the control unit (4) interprets that the temperature of the exhaust gases is low and is not sufficient for pre-heating the emission reduction units (10) in the exhaust gas after treatment unit (100). The third condition may herein be rendered as satisfied if the intake air temperature is found to be lesser than the pre-determined threshold intake air temperature. In an embodiment, the pre-determined threshold intake air temperature may be set by multiple trials where, the emission reduction units (10) reach the required operational temperatures at a given temperature of the intake air which is further set as the pre-determined threshold intake air temperature.

The processing unit of the control unit (4) may further evaluate the first condition, the second condition and the third condition. The bypass valve (7) may be operated by the control unit (4) to direct the intake air through the second path (12) into the intake manifold (1) and bypass the intercooler (6) in the first path (11) when both the first condition and the second condition are satisfied. Particularly, the bypass valve (7) may be operated by the control unit (4) to direct the intake air into the second path (12) when the engine torque is found to be lower than the predetermined threshold torque and when the maximum temperature is found to be lower than the pre-determined first threshold temperature.

The control unit (4) may also operate the bypass valve (7) to direct the intake air into the second path (12) when the intake air temperature is found to be lower than the pre-determined threshold intake air temperature.

Further, the control unit (4) may send a signal for operating the bypass valve (7) and for directing the intake into the second path (12) when both of the first condition and the second condition are satisfied or when the third condition is satisfied. Particularly, the bypass valve (7) may be operated by the control unit (4) to direct the intake air into the second path (12) when the engine torque is found to be lesser than the pre-determined threshold torque and when the maximum temperature is found to be lesser than the pre-determined first threshold temperature or when the intake air temperature is found to be lesser than the pre-determined threshold intake air temperature.

In an embodiment, the temperature of the exhaust gases for pre-heating the emission reduction unit (10) is significantly higher since, the intake air is bypassed by the intercooler (6) and is directly guided into the intake manifold (1). Since the intake air is not cooled by the intercooler (6), the combustion of intake air inside the engine (2) takes at higher temperatures and the temperatures of the exhaust gases also increases consequently. Therefore, higher exhaust gas temperatures enable an efficient pre-heating of the emission reduction unit (10). In an embodiment, the temperatures of the exhaust gases when the intake air is passed through the intercooler (6) is significantly lower than the temperature of the exhaust gases that bypass the intercooler (6). It is therefore evident that the temperature of the exhaust gases is significantly greater when the intake air bypasses the intercooler (6). Consequently, the emission reduction units (10) are pre-heated with higher efficiency and in a shorter time frame.

In an embodiment, the control unit (4) may be configured to send out a signal to operate the bypass valve (7) and direct the intake air through the second path (12) when at least one of the first condition, the second condition and the third condition is satisfied. Particularly, the control unit may send out a signal to operate the bypass valve (7) and direct the intake air through the second path (12) when at least one of the engine torque is found to be lesser than the predetermined threshold torque, when the maximum temperature is found to be lesser than the pre-determined first threshold temperature and when the intake air temperature is found to be lesser than the pre-determined threshold intake air temperature.

In an embodiment, the control unit (4) may be configured to send out a signal to operate the bypass valve (7) and direct the intake air through the second path (12) when the second condition or the third condition is satisfied. Particularly, the control unit may send out a signal to operate the bypass valve (7) and direct the intake air through the second path (12) when the maximum temperature is found to be lesser than the pre-determined first threshold temperature or when the intake air temperature is found to be lesser than the pre-determined threshold intake air temperature. In an embodiment, the fuel efficiency of the vehicle remains un-hindered since the above disclosed method pre-heats the emission reduction units (10) by increasing the exhaust gas temperature through bypassing the intake through the intercooler (6) and the method does not employ fuel consuming process such as post injection, injection timing retardation, intake air throttling etc. In an embodiment, the above-described method does not rely on additive injection/consumption of fuel in the vehicle for pre-heating the emission reduction units (10) and the fuel economy of the vehicle is consequently improved. In an embodiment, the abovedescribed method also enables a faster warm up of the engine by directing the intake air into the engine which is not cooled by the intercooler (6). Consequently, the engine (2) may reach the operational/optimal conditions at a faster rate and is particularly advantageous for vehicles in cold regions. Further, the intake air that is not cooled by the intercooler (6) ensures that a lean mixture of air and fuel is guided into the engine (2) and the combustion is consequently improved.

Equivalents

With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.

It will be understood by those within the art that, in general, terms used herein, are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes but is not limited to," etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding the description may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., "a" and/or "an" should typically be interpreted to mean "at least one" or "one or more"); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to "at least one of A, B, and C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, and C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to "at least one of A, B, or C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, or C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B."

While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated in the description.

Referral Numerals:

Claims

We Claim:

1. A method for pre-heating an exhaust gas after treatment unit (100), the method comprising: receiving by a control unit (4), a signal corresponding to a torque of an engine (2) from an engine torque sensor (2a); receiving by the control unit (4), a signal corresponding to a temperature of a plurality of emission reduction units (10) from a first temperature sensor (9); comparing by the control unit (4), the engine torque with a pre-determined threshold torque; comparing by the control unit, a maximum temperature from the plurality of emission reduction units (10) with a pre-determined first threshold temperature; actuating a bypass valve (7) by a signal from the control unit (4), when the maximum temperature is lesser than the pre-determined first threshold temperature and when the engine torque is lesser than the pre-determined threshold torque; wherein, selective actuation of the bypass valve (7), bypasses the compressed air into an intake manifold (1) of the engine (2) for pre-heating the plurality of emission reduction units (10) to increase the temperature of exhaust gases in the exhaust gas after treatment unit (100).

2. The method as claimed in claim 1 wherein, the control unit (4) receives a signal by a second sensor (5) corresponding to an intake air temperature.

3. The method as claimed in claim 2 comprises, comparing by the control unit (4), the determined intake air temperature with a pre-determined threshold intake air temperature.

4. The method as claimed in claim 3 comprises, opening the bypass valve (7), when the intake air temperature is greater than the pre-determined threshold intake air temperature.

5. The method as claimed in claim 1 wherein, the bypass valve (7) is opened by a signal from the control unit (4) when at least one of the intake air temperature is greater than the pre-determined threshold intake air temperature or when the determined maximum temperature is lesser than the pre-determined first threshold temperature and when the engine torque is lesser than the pre-determined threshold torque. The method as claimed in claim 1 wherein, determining the temperature of the plurality of emission reduction units (10) in the exhaust gas after treatment unit (100) includes determining temperatures of diesel oxidation catalysts (10a), lean NOx trap (10b), diesel particulate filter (10c) and selective catalytic reduction unit (lOd). The method as claimed in claim 1 comprises, comparing by the control unit (4), the temperature of the plurality of emission reduction units (10) for determining the maximum temperature of one of the plurality of emission reduction units (10). A system (200) for pre-heating an exhaust gas after treatment unit (100), the system (200) comprising: a turbocharger (8) configured to receive exhaust gases from an exhaust manifold (3) wherein, a turbine (8b) of the turbocharger (8) is fluidly coupled to the plurality of emission reduction units (10) in the exhaust gas after treatment unit (100); a bypass valve (7) fluidly coupled to a compressor (8a) and configured to receive compressed air from the compressor (8a); a control unit (4) communicatively coupled to at least one temperature sensor (5, 9) in the exhaust gas after treatment unit (100) for determining the temperature of the plurality of emission reduction units (10) and for determining the temperature of the intake air; wherein, the control unit (4) selectively actuates the bypass valve (7) between an open position and a closed position for bypassing the compressed air to the intake manifold (1) of the engine (2) and increases the temperature of exhaust gases from the engine (2) for heating the plurality of emission reduction units (10) in the exhaust gas after treatment unit (100).