DESC:FORM 2
The Patent Act 1970
(39 of 1970)
&
The Patent Rules, 2005

COMPLETE SPECIFICATION
(SEE SECTION 10 AND RULE 13)

TITLE OF THE INVENTION

“EXHAUST GAS MUFFLER”

APPLICANTS:

Name Nationality Address
Mahindra & Mahindra Limited Indian Mahindra & Mahindra Ltd.,
MRV, Mahindra World City (MWC),
Plot No. 41/1, Anjur Post, Chengalpattu,
Kanchipuram District – 603204 (TN) INDIA

The following specification particularly describes and ascertains the nature of this invention and the manner in which it is to be performed:-

TECHNICAL FIELD
[001] The embodiments herein generally relate to noise attenuators and more particularly but not exclusively to improvements in exhaust gas mufflers or silencers for internal combustion engines.

BACKGROUND
[002] Generally, an internal combustion engine produces power by burning an air fuel mixture. The combustion of this air fuel mixture produces exhaust gases that are vented to the atmosphere. The exhaust gases from the engine are vented to the atmosphere through exhaust pipes and muffler/silencer. The exhaust pipes are used for transferring the exhaust gases from the engine while the muffler/silencer is used for reducing the noise emitted by the exhaust gases.
[003] Generally when using a muffler there’s always a trade-off between noise reduction and power produced by the engine. For example a free flow silencer may result in increase in power due to reduced back pressure but results in more noise.
[004] Therefore, there exists a need for an improved muffler/silencer that has low back pressure level and better noise reduction characteristics.

OBJECTS
[005] The principal object of an embodiment of this invention is to provide an exhaust gas muffler that has low back pressure level and better noise reduction characteristics.
[006] Another object of an embodiment of this invention is to provide an exhaust gas muffler that doesn’t affect the fuel efficiency of an engine.
[007] The objects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the 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
[006] This invention is illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which:
[008] Figure 1 depicts a perspective view of the muffler according to an embodiment of the invention as disclosed herein;
[009] Figure 2 depicts a front view of the muffler according to an embodiment of the invention as disclosed herein;
[0010] Figure 3 depicts a front view of the muffler without the perforated shell according to an embodiment of the invention as disclosed herein;
[0011] Figure 4 depicts a perspective view of the second end of the inlet duct of the muffler according to an embodiment of the invention as disclosed herein;
[0012] Figure 5 depicts a perspective view of the perforated shell according to an embodiment of the invention as disclosed herein;
[0013] Figure 6 depicts a front view of the inlet duct of the muffler according to an embodiment of the invention as disclosed herein;
[0014] Figure 7 depicts a front view of the outlet duct of the muffler according to an embodiment of the invention as disclosed herein;
[0015] Figure 8 depicts a front view of the bridging duct of the muffler according to an embodiment of the invention as disclosed herein;
[0016] Figure 9a depicts a front view of the first baffle of the muffler according to an embodiment of the invention as disclosed herein;
[0017] Figure 9b depicts a front view of the second baffle of the muffler according to an embodiment of the invention as disclosed herein;
[0018] Figure 9c depicts a front view of the third baffle of the muffler according to an embodiment of the invention as disclosed herein;
[0019] Figure 10 depicts a perspective view of the muffler without the perforated shell showing the flow of exhaust gases in the muffler according to an embodiment of the invention as discloses herein;
[0020] Figure 11 depicts a graph showing the acoustic transmission loss comparison between a conventional muffler and the muffler according to an embodiment of the invention as disclosed herein; and
[0021] Figure 12 depicts a perspective view of the housing of the muffler according to an embodiment of the invention 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 exhaust gas muffler that has low back pressure level and better noise reduction characteristics. Referring now to the drawings, and more particularly to FIGS. 1 through 12, where similar reference characters denote corresponding features consistently throughout the figures, there are shown embodiments.
[0024] Figure 1 depicts a perspective view of the muffler according to an embodiment of the invention as disclosed herein. Figure 2 depicts a front view of the muffler according to an embodiment of the invention as disclosed herein. Figure 3 depicts a front view of the muffler without the perforated shell according to an embodiment of the invention as disclosed herein. In an embodiment the muffler 100 includes a housing 102, an inlet duct 104, an outlet duct 106, a bridging duct 108, a first baffle 110, a second baffle 112, a third baffle 114, a perforated shell 116 and a sound absorbing element (not shown).
[0025] Figure 12 depicts a perspective view of the housing of the muffler according to an embodiment of the invention as disclosed herein. In an embodiment the housing 102 is used for holding the inlet duct 104, outlet duct 106, bridging duct 108, first baffle 110, second baffle 112, third baffle 114, perforated shell 116 and the sound absorbing element (not shown). In an embodiment the housing 102 is an hollow chamber housing the aforementioned components. In an embodiment the housing 102 includes an inlet 102a and an outlet 102b. In an embodiment the inlet 102a is used for receiving the inlet duct 104 and the outlet 102b is used for receiving the outlet duct 106. In an embodiment the cross-section of the housing 102 is circular in shape and has a internal diameter of 65 mm. However, it is also within the scope of the invention to provide the housing 102 at any other cross-section and internal diameter values without otherwise deterring the intended function of the housing 102 as can be deduced from the description.
[0026] Figure 6 depicts a front view of the inlet duct of the muffler according to an embodiment of the invention as disclosed herein. Figure 4 depicts a perspective view of the second end of the inlet duct of the muffler according to an embodiment of the invention as disclosed herein. In an embodiment the inlet duct 104 is a hollow tube that includes an inlet 104a, an outlet 104b, a plurality of perforations 104c, at least one bend 104d and a bifurcation element 104e. In an embodiment the inlet 104a is provided in fluid communication with an exhaust pipe (not shown) from the engine (not shown) for receiving the exhaust gas from an engine (not shown). In an embodiment the bifurcation element 104e is provided at the outlet 104b of the inlet duct 104 for bifurcating/splitting the outlet 104b of the inlet duct 104 thereby reducing the high frequency sound waves of the exhaust gas exiting from the outlet 104b of the inlet duct 104. In an embodiment the bifurcation element 104e is a sheet metal strip. However, it is also within the scope of the invention to provide strip made from any other material without otherwise deterring the intended function of the bifurcation element 104e as can be deduced from the description. In an embodiment the plurality of perforations 104c in the inlet duct 104 is used for filtering low frequency sound waves from exhaust gas in the inlet duct 104. The perforations 104c filter low frequency sound waves from high frequency sound waves of exhaust gas, thereby the low frequency sound waves of the exhaust gas is absorbed by the sound absorbing element (not shown) in the housing 102, while the high frequency sound waves of exhaust gas travels through the inlet duct 104 thus increasing the acoustic transmission loss. In an embodiment each of the perforations 104c has a diameter of 2mm. However, it is also within the scope of the invention to provide the perforations 104c at any other diameter values without otherwise deterring the intended function of the perforations 104c as can be deduced from the description. In an embodiment the bend 104d is used for increasing the effective length of the inlet duct 104 and the number of perforations 104c thereby increasing the travel of the exhaust gas for better absorption of sound. However it is also within the scope of the invention to provide the inlet duct 104 without the bend 104d. In an embodiment the bend 104d has a radius of 40 mm. However, it is also within the scope of the invention to provide the bend 104d at any other radius values without otherwise deterring the intended function of the bend 104d as can be deduced from the description. In an embodiment the inlet duct 104 has a diameter of 36.5 mm. However, it is also within the scope of the invention to provide the inlet duct 104 at any other diameter values without otherwise deterring the intended function of the inlet duct 104 as can be deduced from the description. The inlet duct 104 is used for receiving the exhaust gas from the engine (not shown) to the housing 102. In an embodiment the cross section of the inlet duct 104 is circular in shape. However, it is also within the scope of the invention to provide the inlet duct 104 in elliptical, oval, semicircle, polygon or at any other cross section without otherwise deterring the intended function of the inlet duct 104 as can be deduced from the description.
[0027] Figure 7 depicts a front view of the outlet duct of the muffler according to an embodiment of the invention as disclosed herein. In an embodiment the outlet duct 106 is a hollow tube that includes an inlet 106a, an outlet 106b, a plurality of first perforations 106c, at least one bend 106d and a plurality of second perforations 106e. In an embodiment the inlet 106a is connected/fastened to the first baffle 110 to prevent the flow of exhaust gas through the inlet 106a of the outlet duct 106. In an embodiment the outlet 106b is vented to the atmosphere. In an embodiment the plurality of first perforations 106c is used for receiving the exhaust gas from the housing 102 into the outlet duct 106. In an embodiment each of the first perforations 106c has a diameter of 3 mm. However, it is also within the scope of the invention to provide the first perforations 106c at any other diameter values without otherwise deterring the intended function of the first perforations 106c as can be deduced from the description. In an embodiment the bend 106d is used to align the outlet 106b of the outlet duct 106 with the axis of the housing 102. However, it is also within the scope of the invention to provide the outlet duct 106 without bend 106d. In an embodiment the bend 106d has a radius of 40 mm. However, it is also within the scope of the invention to provide the bend 106d at any other radius values without otherwise deterring the intended function of the bend 106d as can be deduced from the description. In an embodiment the plurality of second perforations 106e is used for receiving the exhaust gas from the housing 102 into the outlet duct 106. In an embodiment each of the second perforations 106e has a diameter of 3 mm. However, it is also within the scope of the invention to provide the second perforations 106e at any other diameter values without otherwise deterring the intended function of the second perforations 106e as can be deduced from the description. In an embodiment the outlet duct 106 has a diameter of 36.5 mm. However, it is also within the scope of the invention to provide the outlet duct 106 at any other diameter values without otherwise deterring the intended function of the outlet duct 106 as can be deduced from the description. The outlet duct 106 is used for venting the exhaust gas from the housing 102 to the atmosphere. In an embodiment the cross section of the outlet duct 106 is circular in shape. However, it is also within the scope of the invention to provide the outlet duct 106 in elliptical, oval, semicircle, polygon or at any other cross section without otherwise deterring the intended function of the outlet duct 106 as can be deduced from the description.
[0028] Figure 8 depicts a front view of the bridging duct of the muffler according to an embodiment of the invention as disclosed herein. In an embodiment the bridging duct 108 is a hollow tube that includes an inlet 108a and an outlet 108b. The inlet 108a of the bridging duct 108 is provided in fluid communication with the portion of the inlet duct 104 without perforations 104c and the outlet 108b of the bridging duct 108 is provided in fluid communication with the portion of the outlet duct 106 having first perforations 106c as shown in Fig. 3 and Fig. 4. The bridging duct 108 is used for transferring the exhaust gas from the inlet duct 104 to the outlet duct 106 thereby reducing the backpressure level of the muffler 100.
[0029] Figure 10a depicts a front view of the first baffle of the muffler according to an embodiment of the invention as disclosed herein. In an embodiment the first baffle 110 is used for defining a first chamber/partition 118 inside the housing 102 between the portion of the housing 102 having inlet 102a and the first baffle 110. In an embodiment the first baffle 110 includes an opening 110a. In an embodiment the opening 110a is used for receiving the inlet duct 104. The opening 110a is configured based on the size and shape of the inlet duct 104. The side of the first baffle 110 facing the second baffle 112 is connected/fastened to the inlet 106a of the outlet duct 106 for closing the inlet 106a of the outlet duct 106 thereby preventing the flow of exhaust gas through the inlet 106a of the outlet duct 106. The first chamber 118 encloses the portion of the inlet duct 104 having perforations 104c and the first chamber 118 is provided with the sound absorbing element (not shown) for maximum absorption of sound. The first chamber 118 facilitates better acoustic transmission loss by absorbing sound waves of the exhaust gas in the first chamber 118 through the perforations 104c and the sound absorbing element (not shown). The first baffle 110 is configured based on the size and shape of the cross-section of the housing 102. In an embodiment the first baffle 110 is circular in shape and has a diameter of 65mm. However, it is also within the scope of the invention to provide the first baffle 110 in any other shape and dimensions without otherwise deterring the intended function of the first baffle 110 as can be deduced from the description.
[0030] Figure 10b depicts a front view of the second baffle of the muffler according to an embodiment of the invention as disclosed herein. In an embodiment the second baffle 112 is used for defining a second chamber/partition 120 inside the housing 102 between the first baffle 110 and the second baffle 112. In an embodiment the second baffle 112 includes a first opening 112a, a second opening 112b and a plurality of perforations 112c. In an embodiment the first opening 112a is used for receiving the inlet duct 104 and the second opening 112b is used for receiving the outlet duct 106. The first opening 112a and second opening 112b are configured based on the size and shape of the corresponding inlet duct 104 and outlet duct 106. In an embodiment the plurality of perforations 112c is used for facilitating the flow of exhaust gas from the outlet 104b of the inlet duct 104 to the second chamber 120. In an embodiment each of the plurality of perforations 112c has a diameter of 10.5 mm. However, it is also within the scope of the invention to provide the perforations 112c at any other diameter values without otherwise deterring the intended function of the perforations 112c as can be deduced from the description. In an embodiment the inlet duct 104 is received by the first opening 112a such that the outlet 104b of the inlet duct 104 is positioned outside the second chamber 120. The second chamber 120 encloses the bridging duct 108 and the portion of the inlet duct 104 without perforations 104c and the portion of the outlet duct 106 having first perforations 106c. The second chamber 120 is used for absorbing high frequency sound waves from the exhaust gas in the second chamber 120 through the first perforations 106c in the outlet duct 106. In an embodiment the second baffle 112 is circular in shape and has a diameter of 60mm. However, it is also within the scope of the invention to provide the second baffle 112 in any other shape and dimensions without otherwise deterring the intended function of the second baffle 112 as can be deduced from the description.
[0031] Figure 10c depicts a front view of the third baffle of the muffler according to an embodiment of the invention as disclosed herein. In an embodiment the third baffle 114 is used for defining a third chamber/partition 122 inside the housing 102 between the second baffle 112 and the third baffle 114 and for defining a fourth chamber/partition 124 inside the housing 102 between the third baffle 114 and the portion of the housing 102 having the outlet 102b. In an embodiment the third baffle 114 includes an opening 114a and a plurality of perforations 114b. In an embodiment the opening 114a is used for receiving the outlet duct 106. The opening 114a is configured based on the size and shape of the outlet duct 106. In an embodiment the plurality of perforations 114b is used for facilitating the flow of exhaust gas from the outlet 104b of the inlet duct 104 to the fourth chamber 124. In an embodiment each of the plurality of perforations 114b has a diameter of 3 mm. However, it is also within the scope of the invention to provide the perforations 114b at any other diameter values without otherwise deterring the intended function of the perforations 114b as can be deduced from the description. The third chamber 122 encloses the portion of the inlet duct 104 having the outlet 104b and the portion of the outlet duct 106 without first perforations 106c and second perforations 106e. The third chamber 122 is used for reducing the sound pressure levels in the third chamber 122 furthermore through the bifurcation element 104e. The fourth chamber 124 encloses the portion of the outlet duct 106 having the plurality of second perforations 106e and the fourth chamber 124 is provided with sound absorbing element (not shown) for maximum absorption of sound. The fourth chamber 124 is used for absorbing the remaining high frequency sound waves in the fourth chamber 124 through the second perforations 106e in the outlet duct 106 and the sound absorbing element (not shown). In an embodiment the third baffle 114 is circular in shape and has a diameter of 60 mm. However, it is also within the scope of the invention to provide the third baffle 114 in any other shape and dimensions without otherwise deterring the intended function of the third baffle 114 as can be deduced from the description.
[0032] In an embodiment the first chamber 118, second chamber 120, third chamber 122 and the fourth chamber 124 are tuned for absorbing sound waves inside the housing 102 i.e for absorbing sound waves of particular frequency range for better acoustic transmission loss.
[0033] Figure 5 depicts a perspective view of the perforated shell according to an embodiment of the invention as disclosed herein. In an embodiment the perforated shell 116 is a hollow tube that includes a first end 116a, a second end 116b and a plurality of perforations 116c. The perforated shell 116 is provided inside the housing 102 covering the second baffle 112 and the third baffle 114 and the first end 116a of the perforated shell 116 is connected/fastened to the first baffle 110 and the second end 116b of the perforated shell 116 is connected/fastened to the portion of the housing 102 having the outlet 102b as shown in Fig. 1 and Fig. 2. The perforated shell 116 is configured based on the size and shape of the second baffle 112 and third baffle 114. The perforated shell 116 is used for holding the sound absorbing element between the perforated shell 116 and the body of the housing 102 for further absorption of high frequency sound waves in the second chamber 120, third chamber 122 and the fourth chamber 124. The perforations 116c are used for facilitating the absorption of sound waves through the sound absorbing element. The sound absorbing element (not shown) is wrapped around the perforated shell 116 and the perforated shell 116 with the sound absorbing element is provided inside the housing 102. In an embodiment the perforated shell 116 has an internal diameter of 60 mm. However, it is also within the scope of the invention to provide the perforated shell 116 at any other internal diameter values without otherwise deterring the intended function of the perforated shell 116 as can be deduced from the description.
[0034] In an embodiment the sound absorbing element (not shown) is used for maximizing the noise absorption in the muffler 100. In an embodiment the sound absorbing element (not shown) is provided inside the first chamber 118, fourth chamber 124 and around the perforated shell 116 of the muffler 100. However, it is also within the scope of the invention to provide the sound absorbing element in any other chamber of the muffler 100 without otherwise deterring the intended function of the sound absorbing element as can be deduced from the description. In an embodiment the sound absorbing element is glass wool. However, it is also within the scope of the invention to provide rock wool or any other type of sound absorbing element without otherwise deterring the intended function of the sound absorbing element as can be deduced from the description.
[0035] Figure 10 depicts a perspective view of the muffler without the perforated shell showing the flow of exhaust gases in the muffler according to an embodiment of the invention as discloses herein. The working of the muffler 100 is as follows.
[0036] The exhaust gas from the engine (not shown) enters the inlet duct 104 through the inlet 104a and majority of the exhaust gas enters the outlet duct 106 through the bridging duct 108 and exits from the outlet duct 106 through the outlet 106b. Thus, the bridging duct 108 reduces the back pressure level in the muffler 100. The remaining exhaust gas exit through the outlet 104b of the inlet duct 104 and a portion of the exhaust gas enter the first perforations 106c of the outlet duct 106 through the perforations 112c in the second baffle 112 and exit from the outlet duct 106 through the outlet 106b, while another portion of exhaust gas enter the second perforations 106e of the outlet duct 106 through the perforations 114b in the third baffle 114 and exit from the outlet duct 106 through the outlet 106b. The bifurcation element 104e present in the outlet 104b of the inlet duct 104 reduces the high frequency noise and further as the inlet duct 104 and the outlet duct 106 are offset it results in reduction of impact noise. Further the sound absorbing element of the muffler 100 maximizes the noise absorption.
[0037] Figure 11 depicts a graph showing the acoustic transmission loss comparison between a conventional muffler and the muffler according to an embodiment of the invention as disclosed herein. The graphs represent frequency along the x-axis and amplitude along the y-axis. The dotted line in the graph depicts the acoustic transmission loss of the conventional muffler (not shown) and the continuous line depicts the acoustic transmission loss of the muffler 100. Performance tests were conducted on a conventional muffler and the muffler 100 and the results are depicted in the below table. From the below table and acoustic transmission loss graph shown in Fig. 11 it is evident that the muffler 100 has less back pressure level and better noise reduction characteristics.

Parameters Conventional muffler Muffler 100
Pass by Noise in decibels 87.5 83.8
Back pressure in milli bar 18 14

[0038] 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 preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

CLAIMS
We claim
1. A muffler comprising:
an housing having an inlet and an outlet;
an inlet duct having an inlet, an outlet and a plurality of perforations, said inlet duct adapted for receiving an exhaust gas from an engine;
an outlet duct having an inlet, an outlet, a plurality of first perforations and a plurality of second perforations, said outlet duct adapted for venting the exhaust gas from said housing;
a bridging duct having an inlet and an outlet, said bridging duct adapted for transferring exhaust gas from said inlet duct to said outlet duct;
a first baffle having an opening, said first baffle defining a first chamber inside said housing between a portion of said housing having said inlet and said first baffle;
a second baffle having a first opening, a second opening and a plurality of perforations, said second baffle defining a second chamber inside said housing between said first baffle and said second baffle; and
a third baffle having an opening and a plurality of perforations, said third baffle defining, a third chamber inside said housing between said second baffle and said third baffle and a fourth chamber inside said housing between said third baffle and a portion of said housing having said outlet,
wherein
said inlet of said inlet duct is provided in fluid communication with an exhaust pipe from the engine and said outlet of said inlet duct is provided in said third chamber;
said inlet of said outlet duct is connected to said first baffle;
said inlet of said bridging duct is provided in fluid communication with said inlet duct and said outlet of said bridging duct is provided in fluid communication with said outlet duct;
said inlet of said housing is adapted for receiving said inlet duct and said outlet of said housing is adapted for receiving said outlet duct;
said plurality of perforations of said inlet duct is adapted for filtering low frequency sound waves from the exhaust gas in said inlet duct;
said plurality of first perforations and said plurality of second perforations of said outlet duct are adapted for receiving exhaust gas from said housing into said outlet duct;
said opening of said first baffle is adapted for receiving said inlet duct;
said first opening of said second baffle is adapted for receiving said inlet duct and said second opening of said second baffle is adapted for receiving said outlet duct and said plurality of perforations of said second baffle is adapted for facilitating the flow of exhaust gas from said outlet of said inlet duct to said second chamber;
said opening of said third baffle is adapted for receiving said outlet duct and said perforations of said third baffle is adapted for facilitating the flow of exhaust gas from said outlet of said inlet duct to said fourth chamber; and
said first chamber, said second chamber, said third chamber and said fourth chamber, are adapted for absorbing sound waves inside said housing.
2. The muffler as claimed in claim 1, further comprising a sound absorbing element adapted for absorbing sound waves inside said housing of said muffler.
3. The muffler as claimed in claim 1, further comprising a perforated shell having a plurality of perforations, said perforated shell adapted to hold said sound absorbing element.
4. The muffler as claimed in claim 1, wherein said inlet duct further comprises a bifurcation element adapted for bifurcating said outlet of said inlet duct.
5. The muffler as claimed in claim 4, wherein said bifurcation element is a sheet metal strip.
6. The muffler as claimed in claim 1, wherein said inlet duct further comprises a bend adapted for increasing, the effective length of said inlet duct and the number of said perforations of said inlet duct.
7. The muffler as claimed in claim 1, wherein said outlet duct further comprises a bend adapted for aligning said outlet of said outlet duct with the axis of said housing.

Dated this 25th September 2015
Signature:

Name: Kalyan Chakravarthy

ABSTRACT
Exhaust gas muffler includes a housing, an inlet duct, an outlet duct, a bridging duct, a first baffle, a second baffle, a third baffle, a perforated shell and a sound absorbing element. The exhaust gas muffler has less back pressure level and better noise reduction characteristics.
Fig. 1

,CLAIMS:CLAIMS
We claim
1. A muffler comprising:
an housing having an inlet and an outlet;
an inlet duct having an inlet, an outlet and a plurality of perforations, said inlet duct adapted for receiving an exhaust gas from an engine;
an outlet duct having an inlet, an outlet, a plurality of first perforations and a plurality of second perforations, said outlet duct adapted for venting the exhaust gas from said housing;
a bridging duct having an inlet and an outlet, said bridging duct adapted for transferring exhaust gas from said inlet duct to said outlet duct;
a first baffle having an opening, said first baffle defining a first chamber inside said housing between a portion of said housing having said inlet and said first baffle;
a second baffle having a first opening, a second opening and a plurality of perforations, said second baffle defining a second chamber inside said housing between said first baffle and said second baffle; and
a third baffle having an opening and a plurality of perforations, said third baffle defining, a third chamber inside said housing between said second baffle and said third baffle and a fourth chamber inside said housing between said third baffle and a portion of said housing having said outlet,
wherein
said inlet of said inlet duct is provided in fluid communication with an exhaust pipe from the engine and said outlet of said inlet duct is provided in said third chamber;
said inlet of said outlet duct is connected to said first baffle;
said inlet of said bridging duct is provided in fluid communication with said inlet duct and said outlet of said bridging duct is provided in fluid communication with said outlet duct;
said inlet of said housing is adapted for receiving said inlet duct and said outlet of said housing is adapted for receiving said outlet duct;
said plurality of perforations of said inlet duct is adapted for filtering low frequency sound waves from the exhaust gas in said inlet duct;
said plurality of first perforations and said plurality of second perforations of said outlet duct are adapted for receiving exhaust gas from said housing into said outlet duct;
said opening of said first baffle is adapted for receiving said inlet duct;
said first opening of said second baffle is adapted for receiving said inlet duct and said second opening of said second baffle is adapted for receiving said outlet duct and said plurality of perforations of said second baffle is adapted for facilitating the flow of exhaust gas from said outlet of said inlet duct to said second chamber;
said opening of said third baffle is adapted for receiving said outlet duct and said perforations of said third baffle is adapted for facilitating the flow of exhaust gas from said outlet of said inlet duct to said fourth chamber; and
said first chamber, said second chamber, said third chamber and said fourth chamber, are adapted for absorbing sound waves inside said housing.
2. The muffler as claimed in claim 1, further comprising a sound absorbing element adapted for absorbing sound waves inside said housing of said muffler.
3. The muffler as claimed in claim 1, further comprising a perforated shell having a plurality of perforations, said perforated shell adapted to hold said sound absorbing element.
4. The muffler as claimed in claim 1, wherein said inlet duct further comprises a bifurcation element adapted for bifurcating said outlet of said inlet duct.
5. The muffler as claimed in claim 4, wherein said bifurcation element is a sheet metal strip.
6. The muffler as claimed in claim 1, wherein said inlet duct further comprises a bend adapted for increasing, the effective length of said inlet duct and the number of said perforations of said inlet duct.
7. The muffler as claimed in claim 1, wherein said outlet duct further comprises a bend adapted for aligning said outlet of said outlet duct with the axis of said housing.

Dated this 25th September 2015
Signature:

Name: Kalyan Chakravarthy