FIELD OF THE INVENTION
[001] The present invention relates to development of a Compact Modular S-Type Exhaust After-Treatment System Architecture (EATS) for meeting Bharat Stage VT Emission Norms for Heavy Duty Trucks & Buses.
BACKGROUND OF THE INVENTION
[002] To develop an exhaust after-treatment system architecture that is very compact and modular in design such that it can be packaged between the two front steerable axles of a twin-steer heavy-duty truck and in the front overhang area of a heavy-duty bus, for meeting BS-VT emission norms, retaining the same exhaust gas flow-path components to minimize the number of variants.
[003] The catalysts used in the EATS can start functioning only after light-off temperature is attained and it is extremely challenging to attain this temperature quickly, in cold start conditions and also in some duty cycles which predominantly have only low-speed low-load operations. It is further aggravated in the vehicles, where adequate space is not always available to package the EATS closer to the engine. It is also challenging to adapt the same EATS design to various types of vehicle layouts and applications.
OBJECTIVE OF THE INVENTION
[004] The objective of this invention is to develop an EATS architecture that is very compact and modular in design such that it can be packaged between the two front steerable axles of a twin-steer heavy-duty truck and also in the front overhang area of a heavy-duty bus, packaged as close to the engine as possible for retaining the exhaust gas temperatures and for attaining light-off temperatures very quickly and adapting the same EATS design across various vehicle layouts and applications only by changing the orientation of components and the mounting arrangement without changing the exhaust gas flow-path components, for meeting Bharat Stage VT emission norms.

[005] In view of the increasingly stringent emission norms laid out by the government, it is necessary to have a complex, integrated and robust exhaust-after treatment system on-board vehicle, for treating the exhaust gas coming out from the engine. Carbon Monoxide (CO), Unburnt Hydrocarbons (HC), Particulate Matter (PM) and Oxides of Nitrogen (NOx) are major constituents of the exhaust gas, that are regulated.
[006] Diesel Oxidation Catalyst (DOC) is used to oxidize CO and HC to Carbon dioxide (CO2) and H2O (Water) respectively. It also oxidizes Nitric Oxide (NO) in the exhaust gas to Nitrogen dioxide (NO2) and also SOF (Soluble Organic Fraction) part of PM into CO2 and H2O. Diesel Particulate Filter (DPF) is used to trap the PM and the trapped soot particles (Carbon) are then oxidized to CO2 through regeneration process. NOx is reduced in the Selective Catalytic Reduction (SCR) catalyst, by injecting aqueous urea solution in the exhaust gas stream and allowing the urea to decompose into Ammonia (NH3) through thermolysis and hydrolysis reactions, which then reacts with NOx and reduces it to Nitrogen (N2) and H2O. Any excess NH3 left is further oxidized in an Ammonia Slip Catalyst (NH3) placed downstream of the SCR.
[007] All these components are functionally dependent on each other and are integrated as one system called Exhaust After-Treatment System (EATS). The EATS architecture according to present invention is designed in such a way that all major EATS components in the exhaust gas flow-path (DOC, DPF, Hydrolysis pipe, SCR and ASC) are arranged in an S-type layout, in a direction perpendicular to the vehicle frame. This S-type layout is contained within a boundary of size 585 x 550 x 610 mm (L X B X H). All other auxiliary components like sensors and wiring harness are also contained within this boundary
SUMMARY OF THE INVENTION
[008] In one aspect of the invention, an exhaust after treatment system comprises a first layout, a second layout and a third layout. The first layout includes a DOC inlet chamber (1), a Diesel Oxidation Catalyst (DOC) that is connected to the DOC inlet chamber, and a Diesel Particulate Filter (DPF) that is connected to the DOC, wherein exhaust gas from an engine enters the first layout of the system from a down pipe through the DOC inlet chamber in radial direction to the DOC (2) for exhaust treatment. The second layout includes a hydrolysis pipe that is connected to the DPF. In one embodiment, an urea injector placed in the hydrolysis pipe

injects urea solution into the exhaust gas to mix the exhaust gas with the urea solution. The third layout includes a SCR inlet chamber that is connected to the hydrolysis pipe at its anther end to receive the mixed gas with urea solution from the hydrolysis pipe, a SCR catalyst that is connected to the SCR inlet chamber for treating NOx in the mixed gas; and an Ammonia Slip 5 Catalyst (ASC) that is connected said SCR catalyst for treating excess ammonia in the mixed gas.
[009] In one embodiment, the first layout, the second layout and the third layout are arranged in an S-type layout in a direction perpendicular to a vehicle frame. 0
[010] In another embodiment, the S-type layout is contained within a boundary of size in range of 580-640 mm at Length, 540-560 mm at Breadth or Width and 590-610 mm at Height. The system has a tail pipe that is connected to a SCR outlet chamber through V-band clamps.
5 [OH] Further, the system has temperature sensors, NOx sensors and wiring harness
which are integrated in the system.
[012] In yet another embodiment, the wiring harness which connects all sensors such as the temperature sensors (14), and the NOx sensors and acts as single common interface. 0
[013] The system has an additional mixer that is arranged with the hydrolysis pipe to support the mixing process of exhaust gas with urea solution.
[014] In yet another embodiment, mounting brackets are connected to the first, second 5 and third layout components of the system either by means of straps or by means of baffle plates.
[015] The EATS components are welded with the respective mating parts with their
orientation locked in the required angular position. The mounting brackets are connected to the
EATS components either by means of straps or by means of baffle plates, which are then welded
0 to the mounting bracket. Removal of DPF for servicing is easier in this layout, as the catalysts
are placed perpendicular to the vehicle frame.

[016] The DPF is integrated as a serviceable part, which can be removed from the EATS either by means of removing an end cover and sliding the DPF out or by means of removing the V-bands on both the ends of the DPF canning and taking out the DPF. There is a common wiring harness interconnector which connects all the sensors in the EATS and acts as a single common interface for the vehicle side wiring harness. This EATS architecture is made common for all heavy-duty truck applications (haulage, tipper, tractor trailer etc.) and all axle configurations (4 x 2, 6 x 2/4, 8 x 2/4, 10 x 2/4). The same architecture is used for heavy duty bus applications also, with only change in the angular orientation of the welded EATS components and mounting brackets and hence making it a modular design.
BRIEF DESCRIPTION OF THE DIAGRAMS
[017] FIG. la illustrates an isometric view of the S-type EATS architecture;
[018] FIG. lb illustrates an isometric view of the S-type EATS architecture with components name;
[019] FIG. 2 illustrates an isometric view of the EATS packages between the two front steerable axles of a twin-steer heavy duty trucks;
[020] FIG. 3 a illustrates an isometric view of the EATS architecture adapted for a bus layout;
[020] FIG. 3b illustrates an isometric view of the EATS architecture adapted for a bus layout with components name; and
[021] FIG. 4 illustrates an isometric view of the EATS packages in the front overhang area of a heavy-duty bus.
DETAILED DESCRD?TION OF THE DIAGRAMS
[022] The compact modular S-type EATS architecture developed for heavy duty trucks and buses for meeting BS-VT emission norms is shown in Figure la,and lb. The S-type EATS is shown as having three parallel layouts or lanes arranged in the shape of alphabet'S'. First layout or lane of S-shape contains DOC inlet chamber (1), DOC (2) along with its canning and DPF (3)

with its canning. Exhaust gas from the engine enters the EATS from the down pipe (4) through the DOC inlet chamber (1) in radial direction to the DOC (2).
[023] The DOC (2) is placed in perpendicular direction to the vehicle frame and the DOC canning (2) is welded to the DOC inlet chamber (1). The DPF (3) is placed next to the DOC (2) in the same lane. It is connected to the DOC canning (2) either by means of V-band clamps or by welding an outer shell to the DOC canning (2) and allowing the DPF (3) in an inner shell to slide.
[024] The exhaust gas treated in DOC (2) and DPF (3) then enters the DPF outlet chamber (5), which is connected to the DPF canning (3) or the outer shell by means of V-band I clamps on one end and the hydrolysis pipe (6) on the other. The hydrolysis pipe (6) which forms the second lane in the S-shape is where aqueous urea solution is injected into the exhaust stream through the urea injector (7), assisted by compressed air to help mixing of exhaust gas and the aqueous urea solution.
[025] The gap between the first layout and second layout is controlled the by the DPF outlet chamber design.
[026] In one embodiment, an additional mixer (8) might be used in the hydrolysis pipe to support the mixing process. The injected aqueous solution undergoes thermolysis and hydrolysis reactions in the hydrolysis pipe (6) and decomposes to ammonia. The exhaust gas mixed with ammonia enters the SCR inlet chamber (9) which is either welded or connected to the hydrolysis i pipe (6) by means of a V-band clamp. On the other side the SCR inlet chamber (9) is welded to the SCR catalyst (10) canning, which forms the third layout of the S-shape along with ASC (11).
[027] The SCR catalyst (10) is split into two parts which are first brick and second brick for the ease of manufacturing and are placed one after the other. The exhaust gas is treated for NOx in the SCR catalyst (10) and then enters ASC (11) which is zone coated on last few inches of SCR catalyst (10), where any excess ammonia is treated. The completely treated exhaust gas then enters the SCR outlet chamber (12) which is welded to the SCR canning. The other side of the SCR outlet chamber (12) is connected to the tail pipe (13) through V-band clamps. Temperature Sensors (14), NOx Sensors (15), Wiring Harness (16) are integrated in ATS system. The tail pipe (13) can be routed according to the vehicle layouts without affecting the EATS

architecture. This entire EATS architecture is packaged within a boundary of size 585 x 550 x 610 mm (L X B X H), hence making it possible to package the same between the two front steerable axles of a twin-steer heavy-duty truck (Figure 2). The same EATS architecture is also packaged in the front overhang area of a heavy-duty bus (Figure 3 a, 3b and 4), without changing the exhaust gas flow-path components, with only change in the angular orientation of the welded EATS components and mounting brackets within a boundary of size 640 x 548 x 593 mm (L X B X H) and hence making it a truly modular design.

An exhaust after treatment system comprises
a first layout which includes
a DOC inlet chamber (1);
a Diesel Oxidation Catalyst (DOC) (2) that is connected to the DOC inlet chamber (1); and
a Diesel Particulate Filter (DPF) (3) that is connected to the DOC(2), wherein exhaust gas from an engine enters the first layout of the system from a down pipe (4) through the DOC inlet chamber (1) in radial direction to the DOC (2) for exhaust treatment;
a second layout which includes
a hydrolysis pipe (6) that is connected to the DPF (3), wherein an urea injector (7) placed in the hydrolysis pipe (6) injects urea solution into the exhaust gas to mix the exhaust gas with the urea solution;
a third layout which includes
a SCR inlet chamber (9) that is connected to the hydrolysis pipe (6) at its anther end to receive the mixed gas with urea solution from the hydrolysis pipe (6);
a SCR catalyst (10) that is connected to the SCR inlet chamber (9) for treating NOx in the mixed gas; and
an Ammonia Slip Catalyst (ASC) (11) that is connected said SCR catalyst (10) for treating excess ammonia in the mixed gas.

2. The system as claimed in claim 1, wherein the first layout, the second layout and the third
layout are arranged in an S-type layout in a direction perpendicular to a vehicle frame.
3. The system as claimed in claim 1, wherein the S-type layout is contained within a
5 boundary of size in range of 580-640 mm at Length, 540-560 mm at Breadth and 590-610 mm at
Height.
4. The system as claimed in claim 1, comprising
a tail pipe (13) that is connected to a SCR outlet chamber (12) through V-band clamps. 0
5. The system as claimed in claim 1, comprising temperature sensors (14), NOx sensors
(15) and wiring harness (16) which are integrated in the system.
6. The system as claimed in claim 5, wherein the wiring harness (16) which connects all
5 sensors such as the temperature sensors (14), and the NOx sensors (15) and acts as single
common interface.
7. The system as claimed in claim 1, comprising
an additional mixer (8) that is arranged with the hydrolysis pipe (6) to support the mixing 0 process of exhaust gas with urea solution.
8. The system as claimed in claim 1, wherein mounting brackets are connected to the first,
second and third layout components of the system either by means of straps or by means of
baffle plates.