FIELD OF INVENTION
The present invention generally relates to an exhaust system of a vehicle. More particularly, the present invention relates to an exhaust after treatment system with an integrated muffler.
BACKGROUND OF THE INVENTION
Currently exhaust systems designed are very big and costly. As per present market scenario, cost reduction is a major concern and to achieve new emission norms size of exhaust system is significantly increasing.
Thus, there is a need in the art for compact and integrated exhaust after treatment system and mufflers to reduce size, weight, and cost of these systems while simultaneously maintaining emissions within the strict emission regulations, such as the Euro 6 or BS VI emission regulations in Europe and India respectively.
OBJECTIVES OF THE INVENTION
The main objective of this invention is to provide an exhaust after treatment system with an integrated muffler. Another objective of the invention is to provide an exhaust after treatment system with an integrated muffler that is compact.
Yet another objective of the invention is to reduce cost and weight of an exhaust after treatment system for optimizing overall cost of the vehicle and to improve fuel efficiency of the vehicle.
SUMMARY OF THE INVENTION
The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the present invention. It is not intended to identify the key/critical elements of the invention or to delineate the scope of the invention. Its

sole purpose is to present some concept of the invention in a simplified form as a prelude to a more detailed description of the invention presented later.
An exhaust after treatment system with an integrated muffler addresses the need for a compact system to resolve problems related with exhaust gases. The exhaust after treatment system with an integrated muffler comprises an inlet pipe configured to receive exhaust gases and an inlet chamber comprising a deflector configured to distribute the received exhaust gas, where the reflector reduces backpressure and neutralizes sound that contacts the internal walls of the inlet chamber. A catalytic converter assembly is positioned between the inlet chamber and an outlet chamber, where the catalytic converter assembly is configured to oxidise a portion of the exhaust gas and reduce soot particles present in the exhaust gas. The outlet chamber is configured to receive the exhaust gas after being transferred across the catalytic converter assembly and the outlet chamber transfers the exhaust gas to the atmosphere.
In an embodiment, the deflector distributes gas uniformly and enhances improves uniformity index of the exhaust gas. In an embodiment, low and medium frequency sound waves generated due to the exhaust gas are reflected back after contacting the internal walls of the inlet chamber, and the reflected sound waves collide with the sound waves that follow, wherein due to same amplitude of the sound waves, the collision of the sound waves result in attenuation of the sound waves. In an embodiment, glass wool is sandwiched between two sheet metal walls of inlet chamber to reduce high frequency sounds, and wherein the glass wool absorbs and attenuates high frequency sounds. In an embodiment, the catalytic converter assembly comprises of metal foil with chemical coating for chemical reactions.
In an embodiment, the catalytic converter assembly comprises of a metallic brick with chemical coating. In an embodiment, the catalytic converter assembly further comprises a Diesel Oxidation Catalyst (DOC) chamber; and a Particle Oxidation Catalyst (POC) chamber. In an embodiment, after passing through the

inlet chamber, the exhaust gas passes through the DOC chamber, wherein the DOC chamber is positioned in the flow path of the exhaust gas to oxidise the portion of the exhaust gas that includes carbon monoxide and unburned hydrocarbons. In an embodiment, the enhanced uniformity index of the exhaust gas after passing through the deflector further enhances contact between the exhaust gas and the DOC chamber. In an embodiment, after passing through the DOC chamber, the exhaust gas passes through a middle chamber that includes glass wool that is sandwiched between two sheet metal walls around periphery of the middle chamber, wherein the glass wool absorbs the sound waves in the exhaust gas and improves the sound attenuation characteristics of the exhaust gas.
In an embodiment, exhaust after treatment system with an integrated muffler further comprises a perforated plate at the outlet chamber to sandwich the glass wool between the two sheet metal walls. In an embodiment, after passing through the middle chamber the exhaust gas enters the POC chamber, wherein the POC chamber entraps the soot particles from the exhaust gas, and wherein the POC chamber regenerates the soot particles. In an embodiment, the exhaust gas enters the outlet chamber after passing through the POC chamber, and wherein glass wool is sandwiched between two sheet metal walls around the periphery of the outlet chamber to further absorb the sound waves. In an embodiment, exhaust after treatment system with an integrated muffler further comprises an outlet pipe that has an increased outlet face area for reducing wave intensity of the sound waves generated from the exhaust gas.
Aspects of the invention relate to an exhaust after treatment system with an integrated muffler. In the system, exhaust gas from an engine flows through an inlet pipe and enter an inlet chamber where a deflector distributes gas uniformly. The deflector improves uniformity index (>0.95) of the exhaust gasses. The deflector also works as a reflecting chamber. Sounds coming out through the deflector can be categorized in three sound wave categories- low frequency sounds, medium frequency sounds, and high frequency sounds.

According to some aspects, low & medium frequency sounds are reflected back after hitting internal walls of the inlet chamber and collide with the wave following them. Due to same amplitude of these waves, their collision results in attenuation of the sounds. For reducing high frequency sounds, glass wool is sandwiched between two sheet metal walls of inlet chamber. The glass wool absorbs and attenuates high frequency sounds.
According to some aspects, after passing through the inlet chamber, the gas passes through the DOC chamber, where, a catalyst is present in the flow path of the gas. Due to the improved uniformity index of the gas after passing through the deflector, the contact between the gas and the catalyst improves, resulting in better utilization, improved conversion rate, and efficiency of the catalyst.
According to some aspects, after passing through the DOC, the gas passes through a middle chamber where glass wool is sandwiched between two sheet metal walls around the periphery of the middle chamber. The middle chamber absorbs sound waves and improves the sound attenuation characteristic of the system. After passing through middle chamber gas enters a POC, which entraps soot particles coming out of the engine. In the POC, the soot is trapped and regenerated.
According to some aspects, after passing through the POC, the gas enters an outlet chamber which contains glass wool sandwiched between two sheet metal walls around the periphery of the outlet chamber to further absorb sound waves.
According to some aspects, the system reduces both air pollution as well as sound pollution.
Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention.
BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS

Some of the objects of the invention have been set forth above. These and other objects, features, aspects and advantages of the present invention will become better understood with regard to the following description, appended claims and accompanying drawings where:
Figures 1A-1F depict an exhaust treatment system with an integrated muffler, where Figure 1A is a schematic side view, Figure IB is a rear view, Figure IC is a front view, Figure ID is a side view, Figure IE is an isometric view, and Figure IF is a top view, of the exhaust after treatment system with the integrated muffler.
Figures 2A-2F depict enlarged view of different components of the exhaust treatment system with an integrated muffler, where Figure 2A shows the inlet pipe, Figure 2B shows the inlet chamber, Figure 2C shows the DOC, Figure 2D shows the middle chamber, Figure 2E shows the POC, and Figure 2F shows the outlet chamber.
Figures 3 A and 3B show a simplified simulation of the instant invention in Boost 3D software. Figure 3A shows a simplified model where acoustic transmission loss is calculated between two points MP1 and MP2, and Figure 3B shows a graph indicative of the sound attenuation achieved in the above mentioned simulation of the system 100.
Figures 4A-4D show the performance of a CFD model for the system 100, where Figure 4A shows a flow domain where exhaust gas flow from inlet to outlet of the system 100, Figure 4B shows a surface streamline flow in the system 100, Figure 4C shows contour of velocity distribution at substrate inlet face with flow uniformity values of the system 100, and Figure 4D shows the total pressure distribution and pressure drop along the flow through the system 100.
DETAILED DESCRIPTION
The following detailed description should be read with reference to the drawings in which similar elements in different drawings are numbered the same.

The drawings, which are not necessarily to scale, depict illustrative embodiments and are not intended to limit the scope of the invention. Although examples of construction, dimensions, and materials are illustrated for various elements, those skilled in the art will recognize that many of the examples provided have suitable alternatives that may be utilized.
Definitions & Full-forms
The following section includes definitions and full-forms of acronyms used in this specification. If any acronym or word is not defined or elaborated in this section, then said acronym or word will have a meaning commonly defined and acceptable in the art at the time of the filing of this application.
Diesel Oxidation Catalyst (DOC) is the catalyst used to oxidise CO & HC (Carbon Monoxide & Unburned Hydrocarbon) coming from engine exhaust gas.
Particle Oxidation Catalyst (POC) is the substrate used to trap fine soot particles coming out of engine exhaust.
Uniformity Index (UI) shows how uniformly the gas is distributed on the surface area of the substrate. Higher the value of UI confirms better reactions because maximum area is utilized for chemical reactions.
Computational fluid dynamics (CFD) analysis is the methodology to identify fluid flow behaviour inside any geometry. CFD analysis helps to identify the impact of fluid on the system & its performance.
Transmission loss (TL) is defined as the difference between the power incident on a duct acoustic device (muffler) and that transmitted downstream into an anechoic termination.
Overview
The present invention is an exhaust after treatment system with an integrated muffler (hereinafter referred to as the system). In the system, exhaust gas from an

engine flows through an inlet pipe and enter an inlet chamber where a deflector distributes gas uniformly. The deflector improves uniformity index (>0.95) of the exhaust gasses. The deflector also works as a reflecting chamber. Sounds coming out through the deflector can be categorized in three sound wave categories- low frequency sounds, medium frequency sounds, and high frequency sounds.
Low & medium frequency sounds are reflected back after hitting internal walls of the inlet chamber and collide with the wave following them. Due to same amplitude of these waves, their collision results in attenuation of the sounds. For reducing high frequency sounds, glass wool is sandwiched between two sheet metal walls of inlet chamber. The glass wool absorbs and attenuates high frequency sounds.
After passing through the inlet chamber, the gas passes through the DOC chamber, where, a catalyst is present in the flow path of the gas. Due to the improved uniformity index of the gas after passing through the deflector, the contact between the gas and the catalyst improves, resulting in better utilization, improved conversion rate, and efficiency of the catalyst.
After passing through the DOC, the gas passes through a middle chamber where glass wool is sandwiched between two sheet metal walls around the periphery of the middle chamber. The middle chamber absorbs sound waves and improves the sound attenuation characteristic of the system. After passing through middle chamber gas enters a POC, which entraps soot particles coming out of the engine. In the POC, the soot is trapped and regenerated.
After passing through the POC, the gas enters an outlet chamber which contains glass wool sandwiched between two sheet metal walls around the periphery of the outlet chamber to further absorb sound waves. The system reduces both air pollution as well as sound pollution.
Description of Invention

Figures 1A-1F depict orthogonal views of the exhaust after treatment system with an integrated muffler 100 (hereinafter referred to as the system 100). The system 100 includes an inlet pipe 102, an outlet pipe 104, an inlet chamber 106, a DOC 108 of the catalytic converter assembly, a middle chamber 110, a POC 112 of the catalytic converter assembly, and an outlet chamber 114. The inlet pipe 102, outlet pipe 104, inlet chamber 106, DOC 108, middle chamber 110, POC 112, and the outlet chamber 114 are connected to each other via a number of connectors 116. The inlet pipe 102 connects to the inlet chamber 106 via a deflector 118. In some embodiments, the system 100 also includes a mounting bracket 120 for mounting the system 100 on a vehicle body. In some embodiments, the system 100 may be encased in an outer shell to protect the various components of the system 100 from impacts.
The inlet pipe 102 and the outlet pipe 104 are pipes known in the art for use in automotive exhaust systems. The inlet pipe 102 connects the engine of a vehicle to the system 100 and the outlet pipe 104 provides an exit path for exhaust gasses to exit into the environment after treatment.
The deflector 118 connects the inlet pipe 102 to the inlet chamber 106, which distributes the received exhaust gas. The deflector 118 also reduces backpressure and neutralizes sound that contacts the internal walls of the inlet chamber 106. The deflector 118 is a perforated chamber having a number of holes 122 that provide a flow path for exhaust gas coming from the inlet pipe 102, wherein the exhaust gas flows through the deflector 118 into the inlet chamber 106. The holes 122 distribute the exhaust gas evenly in the inlet chamber 106 to improve the uniformity index of the gas flow. The deflector 118 can have any shape, such as a cone, a cylinder, a cuboid, or a combination of such shapes. The perforated deflector 118 at the inlet chamber 106 serves for sound attenuation, UI improvement, and back pressure reduction. The deflector 118 distributes gas uniformly and enhances improves uniformity index of the exhaust gas.

The inlet chamber 106 encases the deflector 118. The inlet chamber 106 includes a double walled top, having a perforated inner wall 124 and a solid outer wall 125. The space between the perforated inner wall 124 and the top wall of the inlet chamber 106 is filled with glass wool 126. The inlet chamber 106 includes a flow path for the gas into the DOC 108. The catalytic converter assembly that is positioned between the inlet chamber 106 and an outlet chamber 114 is configured to oxidise a portion of the exhaust gas and reduce soot particles present in the exhaust gas. The catalytic converter assembly comprises the DOC 108 and the POC 112, which is later explained in detail. The inlet chamber 106 is configured to be in one or more shapes, such as a cone, a cylinder, a cuboid, or a combination of such shapes. In some embodiments, the inlet chamber 106 has a cylindrical shape. In an example, the catalytic converter assembly comprises of metal foil with chemical coating for chemical reactions. The catalytic converter assembly also comprises of a metallic brick with chemical coating, wherein ceramic brick could also be used.
The DOC 108 includes a DOC shell 128 and a substrate 130 housed within the DOC shell 128. The DOC 108 removes polluting gasses such oxides of nitrogen, carbon monoxide, etc., from the exhaust gas flowing through the substrate 130. The DOC 108 includes a flow path for the gas into the middle chamber 110. The DOC 108 is configured to be in one or more shapes, such as a cone, a cylinder, a cuboid, or a combination of such shapes. In some embodiments, the DOC 108 has a cylindrical shape.
The middle chamber 110 provides a cavity between the DOC 108 and the POC 112. The distance between the top and bottom walls of the middle chamber 110 is set such that sound waves reflecting between these two walls interfere destructively to attenuate the sound waves. The sides of the middle chamber 110 are double walled, having an inner perforated wall 132 and an outer solid wall 134. The space between the inner perforated wall 132 and the outer solid wall 134 is filled with glass wool 136. The middle chamber 110 includes a flow path for the gas into the middle POC 112. The middle chamber 110 is configured to be in one or more

shapes, such as a cone, a cylinder, a cuboid, or a combination of such shapes. In some embodiments, the middle chamber 110 has a cylindrical shape.
The POC 112 includes a POC shell 137 and a substrate 138 housed within the POC shell 137. The POC 112 removes soot particles from the exhaust gas flowing through the substrate 138. The POC 112 includes a flow path for the gas into the outlet chamber 114. The POC 112 is configured to be in one or more shapes, such as a cone, a cylinder, a cuboid, or a combination of such shapes. In some embodiments, the POC 112 has a cylindrical shape.
The outlet chamber 114 outputs the exhaust gas from the POC 112 to the outlet pipe 104. The distance between the top and bottom walls of the outlet chamber 114 is set such that sound waves reflecting between these two walls interfere destructively to attenuate the sound waves. The bottom part of the outlet chamber 114 is double walled, having an inner perforated wall 140 and an outer solid wall 142. The space between the inner perforated wall 140 and the outer solid wall 142 is filled with glass wool 144. The outlet chamber 114 is configured to be in one or more shapes, such as a cone, a cylinder, a cuboid, or a combination of such shapes. In some embodiments, the outlet chamber 114 has a hemi-spherical shape. The outlet chamber 114 also comprises of metallic brick.
The connectors 116 can be any type of commonly known connecting structures, such as bands, plates, couplings, etc., that can seal the space between various components of the system 100.
The inlet pipe 102, outlet pipe 104, inlet chamber 106, DOC shell 128, middle chamber 110, POC shell 137, the outlet chamber 114, and the connectors 116 can be made of metal or metal alloys, such as aluminium, steel, etc. In some embodiments, the inlet pipe 102, outlet pipe 104, inlet chamber 106, DOC shell 128, middle chamber 110, POC shell 137, the outlet chamber 114, and the connectors 116 are made of steel. These metal or metal alloy components are made using metal processing operations known in the art, such as stamping, cutting, welding, bolting, 3d printing, etc. The outlet chamber 114 is configured to receive

the exhaust gas after being transferred across the catalytic converter assembly 108 and 112, and the outlet chamber 114 transfers the exhaust gas to the atmosphere via the outlet pipe 104. The outlet pipe 104 has an increased outlet face area for reducing wave intensity of the sound waves generated from the exhaust gas.
The DOC substrate 130 is made of thin sheets of metal (metal foil) with thickness of about 50 microns. This foil is rolled to form honey comb structure coated with suitable chemicals for oxidation of CO and HC (Carbon Monoxide and Unburned Hydrocarbon) coming out of engine exhaust. This ultimately reduces pollution.
The POC substrate 138 is made of flow media manufactured out of sintered metal sheets called fleece. This material has property of trapping soot particles and regenerating them after suitable temperature rise.
Figures 2A-2F depict enlarged view of different components of the exhaust treatment system with an integrated muffler 100, where Figure 2A shows the inlet pipe 102, Figure 2B shows the inlet chamber 106, Figure 2C shows the DOC 108, Figure 2D shows the middle chamber 110, Figure 2E shows the POC 112, and Figure 2F shows the outlet chamber 114. The exhaust gas flows through inlet pipe 102 and enters the inlet chamber 106 where the deflector 118 distributes the exhaust gas uniformly, and due to this the gas has a better uniformity index (>0.95) and it also works as reflecting chamber. Sound coming out through the deflector 118 has three sound waves- low frequency, medium frequency and high frequency. The low and medium frequency sound waves generated due to the exhaust gas are reflected back after contacting the internal walls of the inlet chamber 106, and the reflected sound waves collide with the sound waves that follow. Now, due to same amplitude of the sound waves, the collision of the sound waves result in attenuation of the sound waves.
Low and medium frequency sound are reflecting back after hitting internal walls of the chamber and they collide with the wave following them. Due to same amplitude of these sound waves, they collide and resultant effect is zero. For high

frequency sound, there is glass wool 126 sandwiched between two sheet metal walls of internal chamber 106. The glass wool 126 actually absorbs this sound and resultant is zero. The glass wool 126 is wrapped around inlet chamber 106, connecting portion and outlet chamber 114 for absorbing sound waves. The glass wool 126 is sandwiched between two sheet metal walls of inlet chamber 106 to reduce high frequency sounds, and wherein the glass wool 126 absorbs and attenuates high frequency sounds.
In other words, the means for sound attenuation comprises the glass wool 126 and the sheet metal walls that form a sonic choke arrangement operably positioned as a muffler arrangement.
As shown in Figure 2C, the next component is the catalyst DOC 108 that is positioned in the flow path of the exhaust gas, which is better utilized because of improvised uniformity index attained after passing through the deflector 118. When the exhaust gas passes through the catalyst DOC 108, a better conversion rate is achieved and hence this improves the efficiency of the catalyst. In other words, after passing through the inlet chamber 106, the exhaust gas passes through the DOC 108, wherein the DOC 108 is positioned in the flow path of the exhaust gas to oxidise the portion of the exhaust gas that includes carbon monoxide and unburned hydrocarbons. The enhanced uniformity index of the exhaust gas after passing through the deflector 118 further enhances contact between the exhaust gas and the DOC chamber. As shown in Figure 4D, in the middle chamber 110 where again glass wool 136 is sandwiched between two sheet metal parts around the periphery of the catcon body. The glass wool 136 absorbs sound waves and provides better sound attenuation characteristic to the system. After passing through middle chamber 110, the exhaust gas enters the POC 112 which is used to entrap soot particles that form a part of the exhaust gases from the engine due to combustion.
At the POC 112, the soot is trapped and regenerated, so that these two substrates 130 and 138 serves the purpose of pollution control allows to achieve the BS VI emission norms and to pass by noise criteria. In other words, after passing

through the middle chamber 110 the exhaust gas enters the POC 112, where the POC 112 entraps the soot particles from the exhaust gas, and regenerates the soot particles. Finally, the exhaust gases flow into the outlet chamber 114 that includes an acoustic chamber which is created with the use of baffles perforated pipes to form muffling chamber at the outlet chamber 114. The perforated pipe 148 connecting the two baffles allows the exhaust gas to expand into the acoustic cavity, thereby attenuating the sound. Also, glass wool is placed in the outlet chamber 114 in a space formed between a third perforated baffle and the enclosure of the outlet chamber 114 to absorb high frequency sound waves, and therefore a less polluted exhaust gas with reduced sound is generated through the outlet pipe 104 or the tail pipe. The exhaust treatment system with an integrated muffler 100 completely eliminates the requirement of separate muffler in exhaust systems of three wheelers as in current practise.
In other words, after passing through the DOC, the exhaust gas passes through the middle chamber 114 that includes glass wool 136 that is sandwiched between two sheet metal walls 132 and 134 around periphery of the middle chamber 114. The glass wool 136 absorbs the sound waves in the exhaust gas and improves the sound attenuation characteristics of the exhaust gas. The exhaust gas enters the outlet chamber 114 after passing through the POC 112, and the glass wool 144 is sandwiched between two sheet metal walls 140 around the periphery of the outlet chamber to further absorb the sound waves. In an embodiment, a perforated plate is positioned at the outlet chamber 114 to sandwich the glass wool 144 between the two sheet metal walls 140.
Operation of the system 100
In the system 100, exhaust gas from an engine flows through the inlet pipe 102 and enter the inlet chamber 106 where the deflector 118 distributes gas uniformly. The deflector 118 improves uniformity index (>0.95) of the exhaust gas. The deflector 118 also works as reflecting chamber. Sounds coming out through the

deflector 118 are categorized in three sound wave categories- low frequency sounds, medium frequency sounds, and high frequency sounds.
Low and medium frequency sounds are reflected back after hitting internal walls of the inlet chamber 106 and collide with the wave following them. Due to same amplitude of these waves, their collision results in destructive interference and attenuation of the sounds. For reducing high frequency sounds, glass wool 126 sandwiched between the inner perforated wall 124 and the outer solid wall 125 absorbs and attenuates the high frequency sounds.
After passing through the inlet chamber 106, the exhaust gas passes through the DOC 108, where, the substrate 130 introduces a catalyst in the flow path of the exhaust gas. Due to the improved uniformity index of the exhaust gas after passing through the deflector 118, the contact between the exhaust gas and the catalyst improves, resulting in better utilization, improved conversion rate, and efficiency of the catalyst.
After passing through the DOC 108, the exhaust gas passes through a middle chamber 110 where glass wool 136 is sandwiched between the inner and the outer side walls 132, 134. The middle chamber 110 absorbs sound waves and improves the sound attenuation characteristic of the system 100. After passing through middle chamber 110, the exhaust gas enters the POC 112, which entraps soot particles coming out of the engine. In the POC 112, the soot is trapped and regenerated.
After passing through the POC 112, the exhaust gas enters an outlet chamber 114 which contains glass wool 144 sandwiched between the inner and outer walls 140, 142 to further absorb sound waves. The exhaust gas then exits the outlet chamber 114 through the outlet pipe 104.
Exemplary Embodiments
The following section provides dimensions of an exemplary embodiment of the system 100 suitable for operating with a 600 cc diesel engine.

In an embodiment:
The system has a total length ranging between 300 mm and 320 mm, and a diameter ranging between 100 mm and 120 mm.
The inlet pipe 102 has a diameter ranging between 39 mm and 49 mm.
The outlet pipe 104 has a diameter ranging between 35.3 mm and 38.8 mm.
The inlet chamber 106 is cylindrical in shape. The inlet chamber 106 has a length ranging between 37 mm and 42 mm, and a diameter ranging between 93 mm and 98.3 mm.
The deflector 118 is frustoconical in shape. The deflector 118 has a length ranging between 85.5 mm and 91.5 mm, and a base diameter 21.6 mm to 25 mm, a top diameter of 21.6 mm to 25 mm. The holes 122 are spread across the surface of the deflector and each hole has a diameter ranging between 3 mm and 4 mm.
The DOC shell 128 is cylindrical in shape. The DOC shell 128 has a length ranging between 96.5 mm and 100 mm, and a diameter ranging between 90.5 mm and 93 mm.
The middle chamber 110 is cylindrical in shape. The middle chamber 110 has a length ranging between 25.7 mm and 30.3 mm, and a diameter ranging between 90.2 mm and 93.8 mm.
The POC shell 136 is cylindrical in shape. The POC shell 136 has a length ranging between 120 mm and 126 mm, and a diameter ranging between 90.5 mm and 93 mm.
The outlet chamber 114 is hemi-spherical in shape. The outlet chamber 114 has a diameter ranging between 90 mm and 94 mm.

The DOC substrate 130 is cylindrical in shape. The DOC substrate 130 has a length ranging between 87.5 mm and 90.5 mm, and a diameter ranging between 87.5 mm and 90.5 mm.
The POC substrate 138 is cylindrical in shape. The POC substrate 138 has a length ranging between 117 mm and 121 mm, and a diameter ranging between 87.5 mm and 90.5 mm.
The distance between the inner perforated wall 124 and the outer solid wall 125 ranges between 1 mm and 2.5 mm.
The distance between the inner perforated wall 132 and the outer solid wall 134 ranges between 1 mm and 2.5 mm.
The distance between the inner perforated wall 140 and the outer solid wall 142 ranges between 1 mm and 2.5 mm.
Performance Testing & Experimentation
Figures 3 A and 3B show a simplified simulation of the instant invention in Boost 3D software. Figure 3 A shows a simplified model where transmission loss is calculated between two points MP1 and MP2, and Figure 3B shows a graph indicative of the sound attenuation achieved in the above mentioned simulation of the system 100. As shown in Figure 3 A the simplified model is made using a 3D Mesh: 3DM1 in Boost 3D. The inlet and outlet ports of the mesh is connected to the inlet and outlet of the simulation setup SB1 and SB2 respectively.
The boundary conditions for the simulation are: Inlet Boundary: Inlet Mass flow rate: 68 kg/hr, Temperature: 650°C, Source: Exhaust, and Frequency: 0Hz -2000 Hz; Outlet Boundary: Termination: Anechoic termination
As shown in Figure 3B, the graph depicts an average transmission loss of 30 dB is observed in 0-2000 Hz frequency range. The maximum transmission loss 42dB is observed for 1030 Hz frequency. Frequency sweep from 0-2000Hz is

chosen as the input since actual engine out frequency data is not available. The availability of exhaust frequency range helps to tune the acoustic performance of the exhaust system for that particular frequency range.
Figures 4A-4D show the performance of a CFD model for the system 100, where Figure 4A shows a flow domain where exhaust gas flow from inlet to outlet of the system 100, Figure 4B shows a surface streamline flow in the system 100, Figure 4C shows contour of velocity distribution at substrate inlet face with flow uniformity values of the system 100, and Figure 4D shows the total pressure distribution and pressure drop along the flow through the system 100.
Figure 4A shows a flow domain where exhaust gas flow from inlet to outlet of system 100. Figure 4B represents the streamline of flow inside system 100. Exhaust gases flow from inlet pipe 102 to enter the perforated deflector 118 and then flows out through holes 122 to spread in inlet chamber 106 and then then enters the substrate 130 through a substrate inlet 131. It is seen that exhaust gases flows spreads uniformly in streamline fashion from circular cross section of round pipe to oval entry at deflector inlet without any recirculation zone 146. The size of deflector 118 is optimized to get high flow uniformity (above 0.95) at substrate inlet 131 at the same time to keep the back pressure under the limit. The pattern and size of holes 122 in deflector 118 is also optimized so that flow spreads uniformly without much rise in back pressure. Also some of holes 122 in deflector 118 at the side of substrate 130 are closed to get better flow uniformity at substrate inlet 131. These are holes 122 at far end from inlet of deflector 118 as shown in Fig. 4A. Flow coming out top portion of deflector 118 after hitting wall of inlet chamber 106 bends to enter substrate 130 at portion where the front end of holes 122 rows are closed. Rest of flow comes out through open holes 122 of bottom side of deflector 118 to enter substrate 130. This arrangement leads to complete spread of flow at substrate inlet 131. Also distance between the bottom side of deflector 118 from substrate inlet 131 is optimized so that there is no impingement of flow at substrate inlet 131.

Figure 4C shows the contour of velocity distribution at substrate inlet 131 face with flow uniformity values. At substrate inlet 131, deflector 118 helps to greatly improve uniformity value with almost the same velocity all over the substrate inlet 131. There is not much deviation from average velocity over the entire substrate inlet 131. Also there is no region of high impingement velocity seen at substrate inlet 131. Flow uniformity at POC inlet 113 is very high as flow is already aligned in DOC 108.
Figure 4D shows the total pressure distribution and pressure drop along the flow through system 100. There is very low pressure drop along the inlet pipe 102 as the flow is mostly streamlined along the inlet pipe 102. Pressure drop in inlet chamber 106 is also on lower side due to optimized deflector 118 with pattern and size of the holes 122 to spread flow uniformly and lower the back pressure. Pressure drop in substrate 130 is in accordance with size and configuration. The overall pressure drop across the system 100 is well within the limit of maximum allowable pressure drop and leads to better engine performance.
Various other modifications, adaptations, and alternative designs are of course possible in light of the above teachings. Therefore, it should be understood at this time that within the scope of the appended claims the invention might be practiced otherwise than as specifically described herein.
ADVANTAGES
The present invention presents an exhaust after treatment system with an integrated
muffler that is compact
The present invention reduces cost and weight of an exhaust after treatment system
for optimizing overall cost of the vehicle and improving fuel efficiency of the
vehicle.

Claim

We Claim

1.An exhaust after treatment system with an integrated muffler comprises:
an inlet pipe configured to receive exhaust gases;
an inlet chamber comprising a deflector configured to distribute the received exhaust gas, wherein the deflector reduces backpressure and neutralizes sound that contacts the internal walls of the inlet chamber;
a catalytic converter assembly positioned between the inlet chamber and an outlet chamber, wherein the catalytic converter assembly is configured to oxidise a portion of the exhaust gas and reduce soot particles present in the exhaust gas; and
the outlet chamber configured to receive the exhaust gas after being transferred across the catalytic converter assembly and transfer the exhaust gas to atmosphere.
2. The exhaust after treatment system with an integrated muffler as claimed in claim 1, wherein the deflector distributes gas uniformly and enhances uniformity index of the exhaust gas.
3. The exhaust after treatment system with an integrated muffler as claimed in claim 1, wherein low and medium frequency sound waves generated due to the exhaust gas are reflected back after contacting the internal walls of the inlet chamber, and the reflected sound waves collide with the sound waves that follow, wherein due to same amplitude of the sound waves, the collision of the sound waves results in attenuation of the sound waves.
4. The exhaust after treatment system with an integrated muffler as claimed in claim 1, wherein glass wool is sandwiched between two sheet metal walls of inlet chamber to reduce high frequency sounds, and wherein the glass wool absorbs and attenuates high frequency sounds.

5. The exhaust after treatment system with an integrated muffler as claimed in claim 1, wherein the catalytic converter assembly comprises of metal foil with chemical coating for chemical reactions.
6. The exhaust after treatment system with an integrated muffler as claimed in claim 1, wherein the catalytic converter assembly comprises of a metallic brick with chemical coating.
7. The exhaust after treatment system with an integrated muffler as claimed in claim 1, wherein the catalytic converter assembly further comprises:
a Diesel Oxidation Catalyst (DOC) chamber; and a Particle Oxidation Catalyst (POC) chamber.
8. The exhaust after treatment system with an integrated muffler as claimed in claim 7, wherein after passing through the inlet chamber, the exhaust gas passes through the DOC chamber, wherein the DOC chamber is positioned in the flow path of the exhaust gas to oxidise the portion of the exhaust gas that includes carbon monoxide and unburned hydrocarbons.
9. The exhaust after treatment system with an integrated muffler as claimed in claim 2, wherein the enhanced uniformity index of the exhaust gas after passing through the deflector further enhances contact between the exhaust gas and catalysts in the DOC chamber.
10. The exhaust after treatment system with an integrated muffler as claimed in
claim 1, wherein after passing through the DOC chamber, the exhaust gas passes
through a middle chamber that includes glass wool that is sandwiched between
two sheet metal walls around periphery of the middle chamber, wherein the glass
wool absorbs the sound waves in the exhaust gas and improves the sound
attenuation characteristics of the exhaust gas.

11. The exhaust after treatment system with an integrated muffler as claimed in claim 1, further comprises a perforated plate positioned at the outlet chamber to sandwich the glass wool between two sheet metal walls.
12. The exhaust after treatment system with an integrated muffler as claimed in claim 1, wherein after passing through the middle chamber the exhaust gas enters the POC chamber, wherein the POC chamber entraps the soot particles from the exhaust gas, and wherein the POC chamber regenerates the soot particles.
13. The exhaust after treatment system with an integrated muffler as claimed in claim 1, wherein the exhaust gas enters the outlet chamber after passing through the POC chamber, and wherein glass wool is sandwiched between two sheet metal walls around the periphery of the outlet chamber to further absorb the sound waves.
14. The exhaust after treatment system with an integrated muffler as claimed in claim 1, further comprises an outlet pipe that has an increased outlet face area for reducing wave intensity of the sound waves generated from the exhaust gas.