Claims:We claim:
1. An exhaust diverter (100) in an exhaust after treatment system (10), said exhaust diverter (100) having:
a first portion (102), said first portion (102) defines at least one exhaust opening (102EG) adapted to allow exhaust gas flow therethrough in a first direction to a mixer (304) of a selective catalyst reduction (SCR) system (300);
a second portion (104) angularly extending from said first portion (102), said second portion (104) defines an exhaust opening (104G) and a plurality of perforations (104EG) positioned below said exhaust opening (104G); and
a fin (106) angularly extending from said second portion (104), said fin (106) is adapted to divert the exhaust gas flow from the exhaust opening (104G) of said second portion (104) in a second direction to a region (R) which is in vicinity of a dosing tip of a reagent injector (200) thereby restricting reagent deposit on at least one of the region (R) and the dosing tip of the reagent injector (200).

2. The exhaust diverter (100) as claimed in claim 1, where said exhaust diverter (100) is angularly or perpendicularly oriented relative to said exhaust gas flow thereby creating an exhaust gas recirculation in the region (R) thereby restricting reagent deposit on at least one the region (R) and the dosing tip of the reagent injector (200), where the reagent injector (200) is an air cooled urea injector or a liquid cooled urea injector; and
said region (R) is at least one of reagent injector mounting region, reagent injection region, reagent injector pocket and sections which are in vicinity of the dosing tip of the reagent injector (200) .

3. The exhaust diverter (100) according to claim 1, wherein a diameter of each of said perforation (104EG) of said second portion (104) is in a range from 5 mm to 10 mm; and
said exhaust opening (104G) is adapted to allow exhaust gas flow to said fin (106) thereby directing the exhaust gas flow to dosing tip of the reagent injector (200).

4. The exhaust diverter (100) according to claim 2, wherein a diameter of said exhaust opening (102EG) of said first portion (102) is in a range from 8 mm to 22 mm, where the diameter of each of said perforation (104EG) of said second portion (104) is smaller than the diameter of said exhaust opening (102EG) of said first portion (102).

5. The exhaust diverter (100) as claimed in claim 1, where said plurality of perforations (104EG) of said second portion (102) is adapted to reduce exhaust gas flow therethrough thereby enhancing exhaust gas flow to at least one of the exhaust opening (104G) of said second portion (104) and said exhaust opening (102EG) of said first portion (102).

6. The exhaust diverter (100) as claimed in claim 1, where said first portion (102) defines at least one leg (102L) adapted to be secured inside a de-composition conduit (302) of the selective catalyst reduction (SCR) system (300) and located downstream to said reagent injector (200);
said exhaust diverter (100) is adapted to be angularly mounted to an inlet section of the de-composition conduit (302); and
said fin (106) is substantially parallel to a wall (200MW) of a reagent injector mounting member (300M).

7. The exhaust diverter (100) claimed in claim 1, where said exhaust openings (102EG) of said first portion (102) are vertical slots or horizontal slots or circular slots or rectangular slots or combination thereof; and
said perforations (104EG) of said second portion (104) are vertical slots or horizontal slots or circular slots or rectangular slots or combination thereof.

8. The exhaust diverter (100) as clamed in claim 1, where an angle between said first portion (102) and said second portion (104) is in a range from 120 degrees to 150 degrees.

9. The exhaust diverter (100) as clamed in claim 1, where an angle between said second portion (104) and said fin (106) is in a range from 105 degrees to 135 degrees.

10. An exhaust after treatment system (10) comprising:
a diesel particulate filter (DPF) system in exhaust communication with an engine;
a selective catalyst reduction (SCR) system (300) comprising a decomposition conduit (302) in exhaust communication with said DPF system, a mixer (304), said mixer adapted to be disposed inside said decomposition conduit (302) and a SCR substrate in communication with said decomposition conduit (302);
a reagent injector (200) adapted to inject a reagent into the exhaust stream; and
an exhaust diverter (100) positioned inside said decomposition conduit (302) and located downstream to said reagent injector (200), said exhaust diverter (100) includes,
a first portion (102), said first portion (102) defines at least one exhaust opening (102EG) adapted to allow exhaust gas flow therethrough in a first direction to said mixer (304);
a second portion (104), where said second portion (104) angularly extends from said first portion (102), said second portion (104) defines an exhaust opening (104G) and a plurality of perforations (104EG) positioned below said opening (104G); and
a fin (106), said fin (106) angularly extends from said second portion (104), said fin (106) is adapted to divert the exhaust gas flow from the exhaust opening (104G) of said second portion (104) in a second direction to a region (R) which is in vicinity of a dosing tip of said reagent injector (200) thereby restricting reagent deposit on at least one of the region (R) and the dosing tip of said reagent injector (200).

11. An exhaust gas treatment system (10) as claimed in claim 10, wherein said exhaust diverter (100) is mounted at the bottom portion of an inlet section of said decomposition conduit (302) and located downstream to said reagent injector (200).

12. An exhaust gas treatment system (10) as claimed in claim 10, wherein said perforations (104EG) of said second portion (104) which are vertical slots or horizontal slots or circular slots or rectangular slots or combination thereof; and
said exhaust openings (102EG) of said first portion (102) are vertical slots or horizontal slots or circular slots or rectangular slots or combination thereof.

13. An exhaust gas treatment system (10) as claimed in claim 10, wherein said exhaust diverter (100) covers an entire cross-section of the decomposition conduit (302) for exhaust after-treatment system with air-cooler reagent injector; and
said exhaust diverter (100) is adapted to be angularly mounted to an inlet section of the de-composition conduit (302).

14. An exhaust gas treatment system (10) as claimed in claim 10, wherein exhaust gas treatment system comprises an exhaust restrictor (20) which covers a bottom half of the cross-section of decomposition conduit (302) of said liquid cooled exhaust after-treatment system; and
said exhaust restrictor (20) is perpendicularly oriented relative to exhaust flow and divert the exhaust gas towards a reagent injector mounting region.
, Description:TECHNICAL FIELD
[001] The embodiments herein generally relate to an exhaust after treatment system and more particularly, to an exhaust diverter in the exhaust after treatment system for preventing solid reagent deposition on a reagent injector in a selective catalytic reduction (SCR) system of an internal combustion engine.

BACKGROUND
[002] Presently, selective catalytic reduction (SCR), lean NOx trap (LNT) and exhaust gas recirculation (EGR) systems are used for reducing nitrogen oxides (NOx) emissions from an engine. A NOx to nitrogen (N2) conversion is achieved with the help of catalytic and aqueous urea solution which is injected into the exhaust gas. The selective catalytic reduction is used preferably for medium and heavy load vehicles.
[003] The selective catalytic reduction (SCR) system consists of different metal coated substrate which acts as a catalyst for NOx reduction reactions. The SCR system also includes reagent injector which is used for injecting the reagent. Reagent is an aqueous solution stored onboard and is injected at high pressure into the exhaust gases to achieve atomization. The dosing tip of reagent injector is placed away from the main exhaust flow to prevent the deflection of reagent spray.
[004] Reagent injected into the engine exhaust is decomposed into ammonia (NH3) and this ammonia is absorbed by the SCR brick which later reduces the NOx to N2. This decomposition performed in the decomposition tube leads to thermolysis and hydrolysis reaction of reagent. Further, the SCR system includes mixer which ensures mixing of NH3 with exhaust gas flow.
[005] The efficiency of SCR system is dependent on the ammonia mixing efficiency. The non- uniform mixing may affect SCR efficiency, increase in tailpipe emissions and slip of ammonia which is hazardous to the nature. The evaporation of reagent happens in gaseous state on the walls of the exhaust system. The reagent evaporation on the walls is very critical to the SCR system as it can leads to solid deposits on reagent injector and form by-products like biuret, cyanuric acid or ammelide which results in reduction of efficiency of SCR system and its catalyst. Solid deposits on reagent injector also get formed due to unfavorable vehicle operating conditions or sudden cooling of reagent solution during interaction with walls of exhaust system.
[006] Deposits from reagent are crystalline and melt easily at favorable temperatures, however deposits formed by by-products are hard and stick and it is difficult to clean them from the walls of exhaust systems. Negative impacts of solid deposits on reagent injector of SCR systems are reduction of overall system efficiency, increase in backpressure in exhaust system, increase in fuel consumption and deterioration of emissions. Reagent deposits on the reagent injector also impact the life and durability of the overall system. Further, the urea deposits in the injector mounting region or the dosing tip of the reagent injector results in low mass flow and low temperature of exhaust gas in SCR system.
[007] In water cooled injector SCR system, the surface temperature of the injector tip is much lower than exhaust gas temperature due to coolant flow around injector. Due to the lower temperatures, solid deposition forms on the injector mounting region. Solid deposits thus formed can lead to aggregation of even more deposits. This is how the large crystallization mass develops over the reagent injector. This growth eventually becomes large enough to obstruct exhaust gas flow and/or urea spray thus affecting the NH3 mixing and SCR conversion efficiency.
[008] Therefore, there exists a need for an exhaust diverter in the exhaust gas after treatment system for directing the exhaust gas towards the reagent injector area to facilitate formation of exhaust gas recirculation thereby preventing solid reagent deposition on the reagent injector.

OBJECTS
[009] The principal object of embodiments herein is to provide an exhaust diverter in an exhaust after treatment system.
[0010] Another object of embodiments herein is to provide the exhaust diverter which prevents accumulation of reagent deposit on at least one of a dosing tip of a reagent injector, reagent injector mounting section and a region in vicinity of the dosing tip of the reagent injector.
[0011] Another object of embodiments herein is to provide exhaust restrictor perpendicularly oriented relative to exhaust flow and divert the exhaust gas towards a reagent injector mounting region.
[0012] Another object of embodiments herein is to provide an obstruction to the main exhaust flow in order to channelize the exhaust flow for formation of exhaust recirculation zone and improve the velocity of exhaust in injection zone and mixer.
[0013] Another object of embodiments herein is to increase the exhaust gas velocities near injection holes of water-cooled injector indirectly through exhaust gas recirculation by the exhaust restrictor thereby preventing deposition of reagent deposits on at least one of a dosing tip of the reagent injector and a region which is in vicinity of the dosing tip of the reagent injector.
[0014] Another object of embodiments herein is to increase the exhaust gas recirculation in the reagent injector mounting region even at low exhaust gas flow and low temperature engine operating conditions.
[0015] Another object of embodiments herein is to prevent solid reagent deposition on the reagent injector while doing minimal changes to the overall SCR assembly.
[0016] Another object of embodiments herein is to provide exhaust diverter that helps in reducing the dosing quantity required to cool the injector tip.
[0017] Another object of embodiments herein is to provide an exhaust diverter for preventing the solid deposit formation on the walls of the decomposition tube and mixer in SCR system of a diesel engine.
[0018] Another object of embodiments herein is to provide exhaust diverter plate compatible with reagent injector with inclined mounting on SCR system thereby protecting the injector tip from direct contact with hot gas stream resulting in enhanced life of the injector.
[0019] Another object of embodiments herein is to prevent the solid mass of deposits from obstructing the exhaust gas flow resulting in less backpressure and increased engine power and fuel efficiency.
[0020] Another object of embodiments herein is to increase the exhaust gas velocities near the injector mounting region even at low exhaust gas flow and low temperature operating points.
[0021] Another object of embodiments herein is to increase the life of the air-cooled injector by distancing it from the high temperature main exhaust flow.
[0022] Another object of embodiments herein is to reduce the dosing quantity required to cool the dosing tip for protection of the injector during regeneration.
[0023] These and other objects of embodiments herein will be better appreciated and understood when considered in conjunction with following description and accompanying drawings. It should be understood, however, that the following descriptions, while indicating 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.

SUMMARY OF INVNETION
[0024] In one embodiment of the present invention, an exhaust diverter (100) in an exhaust after treatment system (10) includes a first portion (102), where the first portion (102) defines at least one exhaust opening (102EG) adapted to allow exhaust gas flow therethrough in a first direction to a mixer (304) of a selective catalyst reduction (SCR) system (300), a second portion (104) angularly extending from first portion (102), the second portion (104) defines an exhaust opening (104G) and a plurality of perforations (104EG) positioned below said exhaust opening (104G), and a fin (106) angularly extending from the second portion (104), the fin (106) is adapted to divert the exhaust gas flow from the exhaust opening (104G) of the second portion (104) in a second direction to a region (R) which is in vicinity of a dosing tip of a reagent injector (200) thereby restricting reagent deposit on at least one of the region (R) and the dosing tip of the reagent injector (200).
[0025] In one of the embodiment of the present invention, an exhaust after treatment system (10) includes a diesel particulate filter (DPF) system in exhaust communication with an engine; a selective catalyst reduction (SCR) system (300) comprising a decomposition conduit (302) in exhaust communication with the DPF system, a mixer (304), the mixer adapted to be disposed inside the decomposition conduit (302) and a SCR substrate in communication with said decomposition conduit (302), a reagent injector (200) adapted to inject a reagent into the exhaust stream and an exhaust diverter (100) positioned inside the decomposition conduit (302) and located downstream to the reagent injector (200), the exhaust diverter (100) includes a first portion (102), the first portion (102) defines at least one exhaust opening (102EG) adapted to allow exhaust gas flow therethrough in a first direction to said mixer (304), a second portion (104), where the second portion (104) angularly extends from the first portion (102), the second portion (104) defines an exhaust opening (104G) and a plurality of perforations (104EG) positioned below the exhaust opening (104G) and a fin (106), the fin (106) angularly extends from the second portion (104), the fin (106) is adapted to divert the exhaust gas flow from the exhaust opening (104G) of the second portion (104) in a second direction to an region (R) which is in vicinity of a dosing tip of the reagent injector (200) thereby restricting reagent deposit on at least one of the region (R) and the dosing tip of the reagent injector (200).

BRIEF DESCRIPTION OF DRAWINGS
[0026] The embodiments are illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which:
[0027] Fig. 1 depicts a perspective view of an exhaust diverter, according to embodiments as disclosed herein;
[0028] Fig. 2 depicts a cross-sectional view of an exhaust gas after treatment system, according to embodiments as disclosed herein;
[0029] Fig. 3 depicts another cross-sectional view of the exhaust gas after treatment system, according to embodiments as disclosed herein; and
[0030] Fig. 4 depicts a perspective view of an exhaust restrictor, according to embodiments as disclosed herein.

DETAILED DESCRIPTION
[0031] 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. 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.
[0032] The embodiments herein achieve a an exhaust diverter in the exhaust gas after treatment system for directing the exhaust gas towards the reagent injector area to facilitate formation of exhaust gas recirculation thereby preventing solid reagent deposition on the reagent injector. Referring now to the drawings Figs 1 through 4, where similar reference characters denote corresponding features consistently throughout the figures, there are shown embodiments.
[0033] Fig. 2 depicts a cross-sectional view of an exhaust gas after treatment system (10), according to embodiments as disclosed herein. Fig. 3 depicts another cross-sectional view of the exhaust gas after treatment system (10), according to embodiments as disclosed herein. The exhaust after treatment system (10) includes a diesel particulate filter (DPF) system, an exhaust diverter (100), a reagent injector (200) and a selective catalyst reduction (SCR) system (300). The diesel particulate filter (DPF) system is in exhaust communication with an engine.
[0034] Fig. 1 depicts a perspective view of an exhaust diverter (100), according to embodiments as disclosed herein. In an embodiment, the exhaust diverter (100) is adapted to direct the exhaust gas towards the reagent injector area to facilitate formation of exhaust gas recirculation thereby preventing solid reagent deposition on the reagent injector (200). The exhaust diverter (100) is positioned inside the decomposition conduit (302) and located downstream to the reagent injector (200). The exhaust diverter (100) is below the injector boss casting (200M). In an embodiment, the exhaust diverter (100) includes a first portion (102), a second portion (104) and a fin (106). The first portion (102) of the exhaust diverter (100) defines a plurality of exhaust openings (102EG), as shown in fig. 1 and fig. 2) adapted to allow exhaust gas flow therethrough in a first direction to the mixer (304) of the selective catalyst reduction (SCR) system (300), (as shown in fig. 2). The diameter of the exhaust opening (102EG) of first portion (102) is in a range from 8 mm to 22 mm. For the purpose of this description and ease of understanding, each exhaust opening (102EG) of the first portion (102) is considered to be but not limited to vertical slots or horizontal slots or circular slots or rectangular slots or combination thereof. The exhaust diverter (100) is angularly mounted to an inlet section of the decomposition conduit (302). The first portion (102) of the exhaust diverter (100) defines at least one leg (102L), (as shown in fig. 1) adapted to be secured inside the de-composition conduit (302) of the selective catalyst reduction (SCR) system (300) and located downstream to the reagent injector (200). In an embodiment, an angle between the first portion (104) and the second portion (106) is in a range from 120 degrees to 150 degrees.
[0035] The second portion (104) angularly extends from the first portion (102) of the exhaust diverter (100). The second portion (104) of the exhaust diverter (100) defines an exhaust opening (104G) and a plurality of perforations (104EG) positioned below the exhaust opening (104G). The exhaust opening (104G) is adapted to allow exhaust gas flow to the fin (106) thereby directing the exhaust gas flow to dosing tip of the reagent injector (200). The plurality of perforations (104EG) of second portion (102) of the exhaust diverter (100) is adapted to reduce exhaust gas flow thereby enhancing exhaust gas flow to one of the exhaust opening (104G) of second portion (104) and the exhaust opening (102EG) of the first portion (102). A diameter of perforation (104EG) of the second portion of exhaust diverter (104) is in a range from 5 mm to 10 mm. The diameter of each perforation (104EG) of second portion (104) is smaller than the diameter of exhaust opening (102EG) of first portion (102). For the purpose of this description and ease of understanding, the exhaust opening (104G) and each perforation (104EG) of the second portion (104) is considered to be vertical slots or horizontal slots or circular slots or rectangular slots or combination thereof. In an embodiment, an angle between the second portion (106) and the fin (108) are associated at an angle in a range from 105 degrees to 135 degrees.
[0036] The fin (106) which angularly extends from the second portion (104). The fin (106) is adapted to divert the exhaust gas flow from the exhaust opening (104G) of the second portion (104) in a second direction to a region (R), as shown in fig. 1) which is in vicinity of a dosing tip of a reagent injector (200), (as shown in fig. 2), thereby restricting reagent deposit on at least one of the region (R) and the dosing tip of the reagent injector (200). For the purpose of this description and ease of understanding, the region (R) is considered to be but not limited to reagent injector mounting region, reagent injection region, reagent injector pocket and sections which are in vicinity of the dosing tip of the reagent injector (200). The fin (106) of the exhaust diverter (100) is substantially parallel to a wall (200MW), as shown in fig. 3) of the reagent injector mounting member (300M). The exhaust diverter (100) covers entire cross-section of the decomposition conduit (302) for exhaust after-treatment system with air-cooler reagent injector.
[0037] The selective catalyst reduction (SCR) system (300) includes a decomposition conduit (302), a mixer (304) and a SCR substrate (not shown). The decomposition conduit (302) is in exhaust communication with DPF system. The mixer (304) is adapted to be disposed inside the decomposition conduit (302). The SCR substrate is in exhaust communication with the decomposition conduit (302). The reagent injector (200) is adapted to inject a reagent (urea) into the exhaust stream. The reagent injector (200) is an air cooled urea injector or a liquid cooled urea injector.
[0038] Fig. 4 depicts a perspective view of an exhaust restrictor (20), according to embodiments as disclosed herein. In another embodiment, the exhaust restrictor (20) is perpendicularly oriented relative to the exhaust gas flow thereby creating an exhaust gas recirculation in the region (R) hence restricting reagent deposit on the region (R) and the dosing tip of the reagent injector (200). The exhaust restrictor (20) defines a plurality of perforations (21) with respect to an entirety of portion of the exhaust restrictor (20) in the form of slots. The exhaust restrictor (100) covers bottom half of the cross-section of decomposition conduit (302) of the liquid cooled exhaust after-treatment system. The perforations (21) are considered to be vertical slots or horizontal slots or circular slots or rectangular slots or combination thereof.
[0039] The technical advantages of the exhaust diverter (100) are as follows. NOx conversion efficiency will be maintained thus ensuring that NOx emissions don’t increase significantly with vehicle mileage. Urea consumption will not increase with vehicle mileage. Vehicle performance drop is eliminated. Fuel consumption will not increase with vehicle mileage. Improves the durability and service life for the component by preventing the deposit formation. Major changes to existing decomposition tube geometry are avoided.
[0040] 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 embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modifications within the spirit and scope of the embodiments as described herein.