DESC:CROSS REFERENCE TO RELATED APPLICATION
This Application is based on and derives the benefit of Indian Provisional Application 202141036191 filed on 10th August 2021, the contents of which are incorporated herein by reference

TECHNICAL FIELD
[001] The embodiments herein generally relate to an exhaust muffler in a vehicle and more particularly, to an internal thermal shield system in the exhaust muffler having lock seamed shells and double seamed end covers.

BACKGROUND
[002] Generally, an exhaust system in a vehicle is used to emit the exhaust gases from an engine to the atmosphere in a controlled manner. At the end of engine combustion, hot exhaust gases flow through the exhaust line thereby heating up complete exhaust system which includes pipes and mufflers. A muffler is a device which is used in the exhaust system for attenuating exhaust tail pipe noise. The exhaust system is typically located underbody, routed from engine outlet at the vehicle front, to rear of the vehicle. Exhaust systems need to carry hot exhaust gases through it while multiple interfacing vehicle parts are located around it. To attenuate noise, exhaust gas is exposed to flow restrictions leading to muffler getting heated up. Also exhaust muffler shell and end plates having large surface area become primary heat radiating source for surrounding vehicle components. Exhaust gas temperature entering under floor exhaust system of a typical passenger car and sports utility vehicle goes up to 900 degree Celsius which in turn heat up muffler shells and muffler end plates up to 600 degree Celsius. The vehicle parts in vicinity of exhaust system get heated up due to heat transfer from exhaust system components. In modern vehicles, especially in passenger cars and sports utility vehicles, exhaust need to be routed through tight packaging space wherein adequate clearances cannot be maintained to keep interfacing vehicle parts thermally protected without additional measures. Also, as exhaust system is located below the vehicle body, the floor or carpet where passenger keep their feet or luggage also tend to get heated up in absence of additional measures. To safeguard vehicle components located nearby exhaust system it becomes essential to incorporate thermal shields or heat shields either on the exhaust system components or on the components which need to be thermally protected. Where there are multiple interfacing parts need to be thermally protected from exhaust heat, generally exhaust system component, especially exhaust mufflers are encapsulated with thermal shield.
[003] Generally, exhaust mufflers are of two types from perspective of manufacturing process adopted to produce them. Few mufflers are manufactured by using two stamped shells and welding them with one another. Majority of mufflers are manufactured by rolling and lock seaming metal sheet to form muffler shell and then by double seaming the shell with stamper end plates on either side. Typical muffler thermal shields are thin metal sheets stamped or formed to fit the muffler shape. To ensure higher protection, thermal insulation sheet is inserted between muffler and metal sheet. Most of the muffler thermal shields known in the art are externally mounted thermal shields. Few thermal shield known in the art are internally mounted but they are designed only for stamped mufflers.
[004] In exhaust muffler having lock seamed shells and double seamed end plates, externally mounted thermal shield known in the art encapsulate only muffler shell while both end plates are left exposed. In modern exhaust mufflers, the end plates are embossed, or dome shaped to increase muffler volume and also to improve stiffness which helps in reducing exhaust noise by providing additional acoustic volume or by reducing radiated noise. Because of presence of embossing on the end plates, presence of exhaust pipes which are welded onto the end plates and presence of lock seam between end plate and shell, majority portion of end plates remain uncovered by externally mounted heat shield. Also externally mounted heat shield will have to be welded over the muffler end plates after they are double seamed which creates distortion in the lock seamed zone from where exhaust gas tends to leak. Due to these limitations, externally mounted heat shield is not efficient in thermally encapsulating the end plates in such mufflers.
[005] Therefore, there exists a need for an internal thermal shield system in an exhaust muffler having lock seamed shells and double seamed end covers, which obviates the aforementioned drawbacks.

OBJECTS
[006] The principal object of embodiments herein is provide an internal thermal shield system in an exhaust muffler having lock seamed shells and double seamed end covers, in a vehicle.
[007] Another object of embodiments herein is to provide the internal thermal shield system in the exhaust muffler which can cover maximum surface area of the end covers thereby providing efficient thermal protection to surrounding vehicle parts.
[008] Another object of embodiments herein is to provide the internal thermal shield system in the exhaust muffler, where internal thermal end shields can be welded on the end cover before double seaming with shell such that gas leak performance of muffler assembly is not compromised.
[009] Another object of embodiments herein is to provide the internal thermal shield system with an air gap between internal thermal end shields and muffler end covers, except at the weld flange locations where both mate with each other.
[0010] Another object of embodiments herein is to provide the internal thermal shield with internal thermal insulators inserted between internal thermal end shield and muffler end cover, properties and thickness of which can be varied depending upon extent of thermal protection required.
[0011] Another object of embodiments herein is to provide the internal thermal end shield which stiffens the end cover and also prevents direct contact between gas flow with end cover, thereby lowering noise radiated through the end covers.
[0012] Another object of embodiments herein is to provide the internal thermal shield system which does not require any change in clearances with surrounding parts thereby not requiring any design changes in vehicle parts located around the exhaust muffler which in turn reduce development time and investment.
[0013] 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.

BRIEF DESCRIPTION OF DRAWINGS
[0014] 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:
[0015] Fig. 1 depicts an exploded view of a lock seamed exhaust muffler wherein internal thermal end shields are mounted at both ends of the exhaust muffler’s end covers, according to embodiments as disclosed herein;
[0016] Fig. 2a and Fig. 2b depicts an exploded view of the internal thermal end shields, internal thermal insulators and end covers of the exhaust muffler, according to embodiments as disclosed herein;
[0017] Fig. 3 depicts a cross sectional view of a lock seamed exhaust muffler wherein the internal thermal end shields are positioned at both ends of the exhaust muffler’s end covers, according to embodiments as disclosed herein;
[0018] Fig. 4 depicts a perspective view of an exhaust muffler with lock seamed shell and double seamed end covers with internal thermal ends shield mounted thereon at its inner side, according to embodiments as disclosed herein;
[0019] Fig. 5a and fig. 5b depict a typical vehicle interfaces around exhaust mufflers in a modern sports utility vehicle wherein exhaust line is routed through tight package space and thermal protection of surrounding parts becomes essential;
[0020] Fig. 6a and Fig. 6b depicts color plot showing predicted temperature profile of vehicle’s floor above exhaust line, before and after introduction of the internal thermal end shields on both exhaust muffler’s end covers respectively, according to embodiments as disclosed herein; and
[0021] Fig. 7a and Fig. 7b depicts thermal image showing temperature profile of vehicle’s floor carpet above exhaust line, before and after introduction of the internal thermal end shield on both exhaust muffler’s end covers respectively, according to embodiments as disclosed herein.

DETAILED DESCRIPTION
[0022] 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.
[0023] The embodiments herein achieve an internal thermal shield system in an exhaust muffler having lock seamed shells and double seamed end covers, in a vehicle. Further, embodiments herein achieve embodiments herein achieve the internal thermal shield system in the exhaust muffler which can cover maximum surface area of the end covers thereby providing efficient thermal protection to surrounding vehicle parts. Referring now to the drawings Figs 1 through 7b, where similar reference characters denote corresponding features consistently throughout the figures, there are shown embodiments.
[0024] Fig. 4 depicts a perspective view of the exhaust muffler (10) with lock seamed shell and double seamed end covers (12). These are the most popular type of exhaust mufflers from manufacturing process perspective as they don’t require welding to integrate shell and end covers together and are quick to produce. Fig. 5a and fig. 5b depicts a typical vehicle interfaces around exhaust mufflers in a modern sports utility vehicle wherein exhaust line is routed through under the floor. Due to proximity with exhaust line, especially with exhaust muffler, floor and the carpet tend to become hot unless adequate thermal protection measured are incorporated in design. Also exhaust lines and exhaust muffler are packaged in tight space and thermal protection of surrounding vehicle parts becomes essential. To resolve concern of floor heating in vehicles and to protect surrounding vehicle components, thermal protection is required in the exhaust muffler. Like exhaust muffler shell, both end covers (12) also have large surface areas who contribute significantly to heat transfer to surrounding vehicle parts. Hence it becomes essential to design thermal shield on exhaust muffler end plates. Exhaust muffler being lock seamed type, due to presence of welded exhaust tube, hanger rods, embossing on end plates, it is not possible to design efficient thermal shielding of end plates externally. Exhaust muffler end covers (12) are stamped to have specific embossed profile to ensure higher stiffness and to ensure higher acoustic volume of muffler thereby helping muffler in attenuating exhaust noise and in reducing radiated noise.
[0025] Fig. 1 depicts an exploded view of a lock seamed exhaust muffler wherein internal thermal end shields (102) are mounted at both ends of the exhaust muffler’s end covers (12), according to embodiments as disclosed herein. Fig. 2a and Fig. 2b depicts an exploded view of the internal thermal end shields (102), internal thermal insulators (104) and end covers (12) of the exhaust muffler (10), according to embodiments as disclosed herein. In an embodiment, the internal thermal shield system (100) includes a plurality of internal thermal end shield (102) and a plurality of internal thermal insulators (104).
[0026] Each internal thermal end shield (102) is made of thin metal sheet are also stamped in accordance with shape of corresponding end cover (12). In an embodiment, the internal thermal end shields (102) can be spot welded, or stitch welded with the muffler end cover (12). Each internal thermal end shield (102) is connected to a corresponding end cover (12) of the exhaust muffler (10) at its inner side. Each internal thermal end shield (102) is made of metallic material or non-metallic material. A shape of each internal thermal end shield (102) matches with a shape of corresponding end cover (12).
[0027] Each internal thermal insulator (104) is inserted between the internal thermal end shield (102) and exhaust muffler end cover (12) to have higher thermal protection. Each internal thermal insulator (104) is disposed between corresponding internal thermal end shield (102) and corresponding end cover (12). Each internal thermal insulator (104) is adapted to insulate corresponding end cover (12). At least one of the internal thermal end shields (102) and the internal thermal insulator (104) are adapted to prevent heat dissipation from the end covers (12) of the exhaust muffler (10) thereby preventing heat transfer to components of the vehicle which are located in vicinity of the end covers (12) of the exhaust muffler (10). A shape of each internal thermal insulator (104) matches with the shape of the corresponding end cover (12).
[0028] In the embodiments as disclosed herein, thickness of the internal thermal end shields (102) and thickness of the internal thermal insulators (104) can be varied as per exhaust gas temperatures and the targeted temperature drop across the internal thermal end shields (102). In another embodiment, when the temperature drop requirements are less, the internal thermal insulator (104) is not inserted between the internal thermal end shields (102) and muffler end covers (12). In this case, an air gap is defined between the internal thermal end shield (102) and the end cover (12) of the exhaust muffler (10). The internal thermal end shields (102) and the internal thermal insulators (104) are adapted to restrict exhaust gas to directly contact the end covers (12) thereby dampening noise of the exhaust gas.
[0029] Fig. 6a and Fig. 6b depicts color plot showing predicted temperature profile of vehicle’s floor above exhaust line, before and after introduction of the internal thermal end shields on both exhaust muffler’s end covers respectively, according to embodiments as disclosed herein. The example shows over 460C reduction in surface temperature of the vehicle’s floor when a variant of the internal thermal end shield on the exhaust muffler end cover is introduced.
[0030] Fig. 7a and Fig. 7b depicts thermal image showing temperature profile of vehicle’s floor carpet above exhaust line, before and after introduction of the internal thermal shield on both exhaust muffler’s end cover respectively, according to embodiments as disclosed herein. The example shows over 170C (approx. 300F) reduction in surface temperature of the floor carpet, over which occupants keep their feet, when a variant of the internal thermal shield on the exhaust muffler heat shields are introduced.
[0031] The technical advantages of the internal thermal shield system (100) are as follows. The internal thermal shield system (100) provides design to have thermal protection for stamped end plates of a rolled and lock seamed muffler where conventional externally mounted thermal shields are not efficient. With the internal thermal end shield mounting on exhaust muffler end cover, surrounding vehicle parts can be protected thermally and also temperature of floor and carpet can be maintained below a specified level to ensure occupant comfort. Design of internal thermal end shield can be varied to have varying thickness of internal thermal end shields and varying properties of internal thermal insulator to have desired levels of temperature drop across the internal thermal end shield. Internal thermal end shield assists in reducing radiated noise from muffler end cover by providing stiffness to the end cover and by preventing exhaust gases from directly impinging upon the end cover. Incorporating internal thermal end shield does not require any changes in design of interfacing components of vehicle thereby reducing development time and investment.
[0032] 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.
,CLAIMS:We claim,
1. An internal thermal shield system (100) in an exhaust muffler (10) of a vehicle, said internal thermal shield system (100) comprising:
a plurality of internal thermal end shields (102), wherein each of said internal thermal end shield (102) is connected to a corresponding end cover (12) of the exhaust muffler (10) at its inner side.

2. The internal thermal shield system (100) as claimed in claim 1, wherein said internal thermal shield system (100) includes a plurality of internal thermal insulators (104), wherein each of said internal thermal insulator (104) is disposed between corresponding said internal thermal end shield (102) and corresponding end cover (12).

3. The internal thermal shield system (100) as claimed in claim 2, wherein each of said internal thermal insulator (104) is adapted to insulate corresponding end cover (12).

4. The internal thermal shield system (100) as claimed in claim 3, wherein at least one of said internal thermal end shields (102) and said internal thermal insulator (104) are adapted to prevent heat dissipation from the end covers (12) of the exhaust muffler (10) thereby preventing heat transfer to components of the vehicle which are located in vicinity of the end covers (12) of the exhaust muffler (10).

5. The internal thermal shield system (100) as claimed in claim 4, wherein an air gap is defined between corresponding said internal thermal end shield (102) and corresponding end cover (12) when said internal thermal insulator (104) is removed.

6. The internal thermal shield system (100) as claimed in claim 1, wherein said internal thermal end shields (102) and said internal thermal insulators (104) are adapted to restrict exhaust gas to directly contact the end covers (12) thereby dampening noise of the exhaust gas.

7. The internal thermal shield system (100) as claimed in claim 1, wherein each of said internal thermal end shield (102) is made of metallic material or non-metallic material.

8. The internal thermal shield system (100) as claimed in claim 1, wherein a shape of each of said internal thermal end shield (102) matches with a shape of corresponding end cover (12).

9. The internal thermal shield system (100) as claimed in claim 2, wherein a shape of each of said internal thermal insulator (104) matches with the shape of the corresponding end cover (12).

10. The internal thermal shield system (100) as claimed in claim 1, wherein the end cover (12) is lock seamed shells and double seamed end cover.