DESC:FORM 2

THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENT RULES, 2003

COMPLETE SPECIFICATION
(See Section 10 and Rule 13)

Title of invention:
SYSTEM AND METHOD FOR INCREASING EXHAUST GAS TEMPERATURE TO ENHANCE NOx CONVERSION

Applicant:
BEML Limited
A company Incorporated in India under the Companies Act, 1956
Having address:
BEML Soudha, 23/1, 4th Main,
Sampangirama Nagar, Bengaluru - 560 027,
Karnataka, India

The following specification particularly describes the invention and the manner in which it is to be performed.

CROSS-REFERENCE TO RELATED APPLICATIONS AND PRIORITY

[001] The present invention claims priority from Indian patent Provisional Application 202141007975 filed on 25 February 2021.
TECHNICAL FIELD
[002] The present subject matter described herein, in general, relates to a system and method for raising exhaust gas temperature. More specifically, the present subject matter relates to system and method for raising exhaust gas temperature to reach catalyst light-off temperature of SCR catalyst after starting of an engine and during low load condition.
BACKGROUND
[003] Selective Catalytic Reduction (SCR) is an advanced technology to control emissions in diesel engines. Generally, diesel engines are equipped with SCR (Selective Catalytic Reduction) for NOx reduction and such requires certain temperature for a catalyst light-off. The catalyst light-off is the minimum temperature required to initiate catalytic reaction in SCR catalyst of diesel engine for NOx reduction. However, on account of low load conditions during the initial period after starting of the diesel engine, the temperature of the exhaust gas entering the SCR catalyst will be less than the light-off temperature of catalysts. Thus, the emission of NOx from the exhaust is high due to reduced NOx conversion efficiency in the SCR catalyst. Also, during low load conditions, the Hydrocarbon (HC) emission will be high due to less temperature. So, it is required to achieve light-off temperature as early as possible after the engine start and during low load condition in order to reduce NOx.
[004] Currently available technologies to increase the exhaust gas temperature in diesel engine for achieving the required light-off temperature in SCR catalyst include exhaust back pressure valve for increasing engine back pressure, intake air restriction for reducing intake air flow, post injection in CRDI (Common Rail Direct Injection) system i.e. injecting additional fuel after the regular combustion process. However, these systems are complex to implement.
[005] Hence, there is a need to devise a simple system for reducing NOx and HC emissions from the diesel engine during starting of the engine and low load conditions.
[006] The present disclosure is directed to overcome one or more limitations of the prior art.

OBJECT OF THE INVENTION
[007] Main object of the present invention is to provide a system and method for increasing the exhaust gas temperature for effective functioning of SCR catalyst during initial duration after starting of the engine and during low load conditions.
[008] Another object of the present invention is to provide a system and method for increasing the temperature of intake air during starting of the engine and low load conditions.
[009] Yet another object of the invention is to provide a system and method for reducing the NOx and HC emissions from the diesel engine during starting of the engine and low load conditions.
[0010] Yet another object of the invention is to provide a system and method to achieve catalyst light-off temperature at the earliest during starting of the diesel engine and during low load conditions.
[0011] Yet another object of the invention is to provide a system and method to enhance conversion efficiency of SCR.
STATEMENT OF THE INVENTION
[0012] Accordingly, the present invention relates to a system for increasing an exhaust gas temperature to enhance NOx conversion comprising a Selective Catalytic Reduction (SCR) catalyst in an exhaust system of an engine, an electric heater mounted in an air intake manifold configured to heat an exhaust gas before entering the SCR and an ECU configured to monitor temperature of the exhaust gas on real time basis and control the operation of the electric heater based on the temperature feedback.
[0013] The electric heater is configured to be mounted between the air intake manifold and a cylinder head and is configured to be operated through vehicle battery. Said electric heater is further configured to be switched ON for predefined time duration followed by switching OFF the electric heater for preset time wherein the switching ON and OFF action of the electric heater is continued till the exhaust gas temperature rises to desired temperature. Further, the ECU is configured to detect the temperature in a region before SCR catalyst and based on temperature detection, controls ON and OFF condition of the electric heater. The ECU is configured to operate a cycle of switching ON the electric heater for 60 sec followed by switching off the electric heater for 2 minutes time interval repeatedly till the exhaust gas temperature rises to light-off temperature. Moreover, the ECU is configured to switch ON the electric heater during initial duration after engine start and during low load conditions to reduce NOx to the required target level.
[0014] Furthermore, a method for increasing an exhaust gas temperature to enhance NOx conversion comprises steps of: starting an engine and monitoring exhaust gas temperature, monitoring temperature of the exhaust gas in a region before SCR catalyst by an ECU in real time, switching ON an electric heater by the ECU if the detected temperature is below predefined temperature, switching OFF the electric heater by the ECU after predefined time interval and detecting real time achieved temperature in a region before SCR catalyst by the ECU for switching ON the electric heater after predefined time interval if desired temperature is not achieved and said cycle is repeated till the exhaust gas temp reaches to light-off temp. The said predefined temperature is configured to vary according to type of vehicle.
SUMMARY
[0015] Before the present system and method are described, it is to be understood that this application is not limited to the particular machine or an apparatus, and methodologies described, as there can be multiple possible embodiments that are not expressly illustrated in the present disclosures. It is also to be understood that the terminology used in the description is for the purpose of describing the particular versions or embodiments only, and is not intended to limit the scope of the present application. This summary is provided to introduce aspects related to a system and method for increasing exhaust gas temperature, and the aspects are further elaborated below in the detailed description. This summary is not intended to identify essential features of the proposed subject matter nor is it intended for use in determining or limiting the scope of the proposed subject matter.
[0016] The present invention relates to a system and a method for increasing intake air temperature in a diesel engine to enhance NOx conversion. The system mainly comprises an electric heater to be mounted in an air intake manifold of the engine. Further, the system comprises an ECU to control the operation of the electric heater by real time monitoring of temperature of an exhaust gas in a region before SCR catalyst. The ECU is configured to switch ON electric heater during initial duration after engine start and during low load conditions to achieve light-off temperature of the exhaust gas resulting in reduced NOx level. When the temperature of the exhaust gas is below predefined limit, the ECU switches ON the electric heater for predefined time duration in order to increase the exhaust gas temperature and switches OFF the electric heater after that time duration. The ECU detects the exhaust gas temperature in real time to check whether the predefined temperature is achieved and based on that repeats the electric heater ON and OFF conditions. Further, said cycle is repeated till the exhaust gas temperature reaches to the desired limit wherein the electric heater is switched ON in predefined time intervals to safeguard the electric heater from overheating.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The foregoing summary, as well as the following detailed description of embodiments, is better understood when read in conjunction with the appended drawing. For the purpose of illustrating the disclosure, there is shown in the present document example constructions of the disclosure, however, the disclosure is not limited to the specific methods and apparatus disclosed in the document and the drawing:
[0018] The detailed description is described with reference to the accompanying figure. In the figure, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawing to refer like features and components.
[0019] Figure 1 illustrates a system for increasing intake air temperature of diesel engine.
[0020] Figure 2 illustrates an engine intake manifold and an electric heater for increasing intake air temperature of diesel engine.
[0021] Figure 3 illustrates a method for increasing intake air temperature of diesel engine.
[0022] The figure depicts various embodiments of the present disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following discussion that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DETAILED DESCRIPTION
[0023] Some embodiments of this disclosure, illustrating all its features, will now be discussed in detail. The words "comprising", “having”, and "including," and other forms thereof, are intended to be equivalent in meaning and be open ended in that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items, or meant to be limited to only the listed item or items. Although any systems and methods similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present disclosure, the exemplary, systems and methods are now described. The disclosed embodiments are merely exemplary of the disclosure, which may be embodied in various forms.
[0024] Various modifications to the embodiment will be readily apparent to those skilled in the art and the generic principles herein may be applied to other embodiments. However, one of ordinary skill in the art will readily recognize that the present disclosure is not intended to be limited to the embodiments illustrated, but is to be accorded the widest scope consistent with the principles and features described herein.
[0025] The present invention described herein refers to a system and a method for increasing intake air temperature in a diesel engine to enhance NOx conversion. The proposed system mainly comprises a heater particularly an electric heater to be mounted in an air intake manifold of said engine. The temperature of an exhaust gas of the engine is increased by said electric heater before entering the SCR catalyst or during initial duration after engine start and during low load conditions. The electric heater helps to achieve the light-off temperature of the exhaust gas in very less time which improves conversion efficiency of SCR. Hence, said SCR is capable of reducing NOx to required target level.
[0026] Referring now to figure 1 and figure 2, a system (100) for increasing intake air temperature of diesel engine to enhance NOx conversion is disclosed. The system (100) comprises a diesel engine mounted with an intake manifold (102) for supplying air for combustion of air-fuel mixture in combustion chamber of cylinder. An electric heater (104) is configured to be mounted between said air intake manifold and an intake cross over or CAC connector (108). An electronic control unit (ECU) (106) is configured to operate said electric heater (104) when the temperature of the region before the SCR catalyst is less than the light-off temperature.
[0027] The ECU (106) is configured to monitor temperature of the region before the SCR catalyst on a real time basis. When the temperature of the region before the SCR catalyst is below the light-off temperature, the ECU (106) signals said electric heater (104) to operate for a pre-defined time to raise the temperature of the air entering said intake air manifold (102). In the present embodiment, the electric heater (104) is operated for 60 sec. The electric heater (104) is activated by supplying a direct current (DC) from a battery. Thus, the temperature of the exhaust gas rises to the required level and the SCR catalyst operates at a higher efficiency to reduce toxic NOx and HC emissions. Further, said ECU (106) is configured to turn off said electric heater (104), when the temperature of the region before the SCR catalyst reaches the light-off temperature.
[0028] Referring now to figure 3, a method (200) for increasing intake air temperature of diesel engine is disclosed. The method (200) comprises starting an engine and monitoring exhaust gas temperature in region before SCR catalyst. The method (200) comprises operating an electric heater (104) for a pre-defined time if the exhaust gas temperature is below a pre-defined temperature. In the present embodiment, the electric heater (104) is operated for 60 sec. In the present embodiment, the pre-defined temperature of the exhaust gas is configured to be 250 degrees Celsius. Further, after said electric heater (104) has been operated and stopped, the temperature of the exhaust gas is again monitored to verify whether the desired temperature of the exhaust has been achieved or not. If the desired temperature of the exhaust gas has been achieved, the ECU (106) signals to stop the operation of said electric heater (104). In case the desired temperature has not been achieved, said ECU (106) signals said electric heater (104) to pause operation for a pre-defined time period before re-starting the operation of said electric heater (104) to achieve the desired temperature. In the present embodiment, the electric heater (104) is re-started after 2 min interval to safeguard the electric heater (104).
[0029] Furthermore, the present invention particularly discloses a system for increasing an exhaust gas temperature comprising a Selective Catalytic Reduction (SCR) catalyst in an exhaust system of an engine, an electric heater (104) mounted in an air intake manifold (102) configured to heat an exhaust gas before entering the SCR and an ECU (106) configured to monitor temperature of the exhaust gas on real time basis and control the operation of the electric heater (104) based on the temperature feedback. The electric heater (104) is configured to be mounted between the air intake manifold (102) and a cylinder head and is configured to be operated through vehicle battery. Said electric heater (104) is further configured to be switched ON for predefined time duration followed by switching OFF the electric heater (104) for preset time wherein the switching ON and OFF action of the electric heater (104) is continued till the exhaust gas temperature rises to desired temperature. Further, the ECU (106) is configured to detect the temperature in a region before SCR catalyst and based on temperature detection, controls ON and OFF condition of the electric heater (104). The ECU (106) is configured to operate a cycle of switching ON the electric heater (104) for 60 sec followed by switching off the electric heater (104) for 2 minutes time interval repeatedly till the exhaust gas temperature rises to light-off temperature. Moreover, the ECU (106) is configured to switch ON the electric heater (104) during initial duration after engine start and during low load conditions to reduce NOx to the required target level.
[0030] Furthermore, a method for increasing an exhaust gas temperature to enhance NOx conversion comprises steps of: starting an engine and monitoring exhaust gas temperature, monitoring temperature of the exhaust gas in a region before SCR catalyst by an ECU (106) in real time, switching ON an electric heater (104) by the ECU (106) if the detected temperature is below predefined temperature, switching OFF the electric heater (104) by the ECU (106) after predefined time interval and detecting real time achieved temperature in a region before SCR catalyst by the ECU (106) for switching ON the electric heater (104) after predefined time interval if desired temperature is not achieved and said cycle is repeated till the exhaust gas temp reaches to light-off temp. The said predefined temperature is configured to vary according to type of vehicle.
[0031] Further, the invention can be used, but not limited to, in the following applications.
[0032] Exemplary embodiments discussed above may provide certain advantages. Though not required to practice aspects of the disclosure, these advantages may include those provided by the following features.
[0033] Some object of the present invention provides controlling of electric heater by ECU based on detected temperature of SCR catalyst.
[0034] Some object of the present invention is to provide a simple and cost effective design for reducing NOx and HC emissions.
,CLAIMS:
1. A system for increasing an exhaust gas temperature to enhance NOx conversion comprising:
a Selective Catalytic Reduction (SCR) catalyst in an exhaust system of an engine;
an electric heater (104) mounted in an air intake manifold (102) configured to heat an exhaust gas before entering the SCR; and
an ECU (106) configured to monitor temperature of the exhaust gas on real time basis and control an operation of the electric heater (104) based on the temperature feedback.
2. The system for increasing the exhaust gas temperature to enhance NOx conversion wherein, the electric heater (104) is configured to be mounted between the air intake manifold (102) and a cylinder head.
3. The system for increasing the exhaust gas temperature to enhance NOx conversion wherein, the electric heater (104) is configured to be operated through vehicle battery.
4. The system for increasing the exhaust gas temperature to enhance NOx conversion wherein, the electric heater (104) is configured to be switched ON for predefined time duration followed by switching OFF the electric heater (104) for preset time wherein the switching ON and OFF action of the electric heater (104) is continued till the exhaust gas temperature rises to desired temperature.
5. The system for increasing the exhaust gas temperature to enhance NOx conversion wherein, the ECU (106) is configured to detect the temperature in a region before SCR catalyst and based on temperature detection, controls ON and OFF condition of the electric heater (104).
6. The system for increasing the exhaust gas temperature to enhance NOx conversion wherein, the ECU (106) is configured to operate a cycle of switching ON the electric heater (104) for 60 sec followed by switching off the electric heater (104) for 2 minutes time interval repeatedly till the exhaust gas temperature rises to light-off temperature.
7. The system for increasing the exhaust gas temperature to enhance NOx conversion wherein, the ECU (106) is configured to switch ON the electric heater (104) during initial duration after engine start and during low load conditions to reduce NOx to the required target level.
8. A method for increasing an exhaust gas temperature to enhance NOx conversion comprises steps of:
starting an engine and monitoring exhaust gas temperature;
monitoring temperature of the exhaust gas in a region before SCR catalyst by an ECU (106) in real time;
switching ON an electric heater (104) by the ECU (106) if the detected temperature is below predefined temperature;
switching OFF the electric heater (104) by the ECU (106) after predefined time interval; and
detecting real time achieved temperature in a region before SCR catalyst by the ECU (106) for switching ON the electric heater (104) after predefined time interval if desired temperature is not achieved and said cycle is repeated till the exhaust gas temp reaches to light-off temp.
9. The method for increasing the exhaust gas temperature to enhance NOx conversion wherein, said predefined temperature is configured to vary according to type of vehicle.