TECHNICAL FIELD

The present disclosure relates to an exhaust muffler of an automobile. More particularly  the disclosure relates to a muffler for a heavy commercial vehicle.

BACKGROUND OF THE DISCLOSURE

In prior art there are fixed opening area for exhaust gases to pass through the muffler which is a disadvantage  at low rpm the opening area(i.e. opening between two chamber of a multi chamber silencer  in fig 10 total area of (301)and (303) is the opening area)required for sound attenuation is very less but when the muffler is provided with higher opening area  it will create more noise and at higher rpm the opening area provided for muffler should be larger if it is comparatively less  due to lower opening area more back pressure is created and the engine performance is affected.

An existing muffler for a combustion engine includes a casing having an inlet opening  an outlet opening  a first partition secured in the casing to divide incoming exhaust gases  a second partition secured in the casing downstream of the first partition and an intermediate partition is placed between the said first partition and second partition. The second partition has an opening through which the divided exhaust gases are converged and expelled out. The intermediate partition produces both sound attenuation and lower operating back pressure. The intermediate partition facing towards the first partition having concave surface reflects sound waves in a direction away from the opening of the second partition.

Another example discloses a conventional system  wherein the sound attenuation device is provided with a solid baffle plate and a perforated baffle plate whose diameter is proportional to the inner diameter of the elongated chamber and is funnel shaped. A central baffle tube is provided with inwardly angled louvers spaced equally around the circumference which routes the exhaust gases through the chamber. A central hole is provided in the baffle plates whose diameter is corresponds to the diameter of the baffle tube.

These existing conventional systems currently possesses more components  hence requires more assembly time and increase cost of the product.
The prior-art mufflers are typically a combination of reaction and absorption elements. These are costlier  have more weight and difficult to manufacture.

Hence  there exist needs to develop a muffler with less weight  less number of components and easy to manufacture.
STATEMENT OF THE DISCLOSURE

Accordingly  the disclosure provides a muffler comprising  a muffler body having at least one inlet and at least one outlet of predetermined shape on either ends  at least one baffle plate having plurality of holes placed inside the muffler at a predetermined location to bifurcate the muffler body into plurality of chambers and at least one pressure control valve placed inside at least one of the chamber  wherein said pressure control valve comprises  a control rod placed axially inside the chambers and a movable plate mounted on the control rod at vicinity of one of the plurality of holes of the baffle plate connecting adjacent chamber such that the movable plate is displaced when pressure inside the adjacent chamber exceeds a predetermined limit  wherein the predetermined limit is set by adjusting the control rod  the disclosure also provides a method for controlling back pressure of a muffler comprises  displacing a movable plate mounted on a control rod placed in a chamber at vicinity of at least one hole of a baffle plate placed inside muffler body to release exhaust gases when pressure inside the adjacent chamber exceeds a predetermined limit  wherein the predetermined limit is set by adjusting the control rod.
SUMMARY OF THE DISCLOSURE

The shortcomings of the prior art are overcome and additional advantages are provided through the provision of innovated muffler as claimed in disclosure.

Additional features and advantages are realized through the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed disclosure.

The disclosure provides a muffler comprising a muffler body having at least one inlet and at least one outlet of predetermined shape on its either ends. Further at least one baffle plate having plurality of holes is placed inside the muffler at a predetermined location to bifurcate the muffler body into plurality of chambers. In addition at least one pressure control valve is placed inside at least one of the chamber  wherein said pressure control valve comprises  a control rod placed axially inside the chambers and a movable plate mounted on the control rod at vicinity of one of the plurality of holes of the baffle plate connecting adjacent chamber such that the movable plate is displaced when pressure inside the adjacent chamber exceeds a predetermined limit  wherein the predetermined limit is set by adjusting the control rod.

In one embodiment of the present disclosure the pressure control valve consists a spring of predetermined stiffness welded between the movable plate and a fixed plate and is mounted concentrically at first end of the control rod  wherein said fixed plate is welded to the control rod. The spring compresses and expands based on the pressure in the adjacent chamber.

An adjusting mechanism  for adjusting control rod is provided as one of the aspect of the present disclosure. The adjusting mechanism comprises: a mounting bracket having plurality of legs welded to the baffle plate to support the control rod on first end. Further at least one stopper is provided on the first end of the control rod to limit movement of the control rod  wherein the mounting bracket is mounted between the stopper and the baffle plate. In addition a threaded portion is formed on second end of the control rod. Further a slot on the second end of the control rod is provided which is displaced for adjusting the control rod  wherein the slot is mounted externally to the chamber  which is operated manually.

In one embodiment of the present disclosure a pressure relief valve is connected to the at least one of the chambers  wherein said valve opens to atmosphere in case of excess pressure accumulated inside the chamber.

A method of controlling back pressure of a muffler is provided as one aspect of the present disclosure. The method comprises  displacing a movable plate mounted on a control rod placed in a chamber at vicinity of at least one hole of a baffle plate placed inside muffler body to release exhaust gases when pressure inside the adjacent chamber exceeds a predetermined limit  wherein the predetermined limit is set by adjusting the control rod.

In an alternative embodiment  the disclosure provides a muffler comprising  a muffler body having at least one inlet and at least one outlet of predetermined shape on either ends. Further at least one baffle plate having plurality of holes is placed inside the muffler at a predetermined location to bifurcate the muffler body into chambers and at least one pressure control valve placed inside at least one of the chamber  wherein said pressure control valve comprises  a mounting bracket welded to at least one hole of the baffle plate and a movable plate at vicinity of said hole of the baffle plate connecting adjacent chamber such that the movable plate connected to said mounting bracket by a spring which displaces when pressure inside the adjacent chamber exceeds a predetermined limit.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects  embodiments  and features described above  further aspects  embodiments  and features will become apparent by reference to the drawings and the following detailed description.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The novel features and characteristic of the disclosure are set forth in the appended claims. The disclosure itself  however  as well as a preferred mode of use  further objectives and advantages thereof  will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying figures. One or more embodiments are now described  by way of example only  with reference to the accompanying figures wherein like reference numerals represent like elements and in which:

FIG. 1 illustrates schematic representation of the muffler viewed from front according to the disclosure.

FIG. 2 illustrates schematic representation of the top view of the muffler according to the disclosure.

FIG. 3 illustrates schematic representation of the left view of the muffler according to the disclosure.

FIGS. 4 and 5 illustrate Isometric wire mesh view according to the disclosure.

FIGS. 6a  6b & 6c illustrate schematic representation of the inlet according to the disclosure.

FIGS. 7a  7b & 7c illustrate Isometric view of the outlet according to the disclosure.

FIGS. 8a  8b & 8c illustrate the view of the pressure relief valve according to the disclosure.

FIG. 9a  9b  9c & 9d illustrate the view of the pressure control valve according to the disclosure.
FIG.10 illustrates the schematic representation of the second baffle plate (107) viewed from right side according to the disclosure.

The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DETAIL DESCRIPTION

The foregoing has broadly outlined the features and technical advantages of the present disclosure in order that the detailed description of the disclosure that follows may be better understood. Additional features and advantages of the disclosure will be described hereinafter which form the subject of the claims of the disclosure. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the disclosure as set forth in the appended claims. The novel features which are believed to be characteristic of the disclosure  both as to its organization and method of operation  together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood  however  that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure.

It is to be noted at this point that all of the above described components  whether alone or in any combination  are claimed as being essential to the disclosure  in particular the details depicted in the drawings and reference numerals in the drawings are as given below.

Referral Numerals Description
101 Muffler
102 Muffler Body
103 Inlet Tube
104 Outlet Tube
105 Perforated Jacket
106 First Baffle Plate
107 Second Baffle Plate
108 Pressure Control Valve
109 Pressure Relief Valve
110 End Plate
111 Outer Jacket
112 Glass Wool
113 First Chamber
114 Second Chamber
115 Third Chamber
301 First Hole and second hole on second baffle plate
303 Third Hole on second baffle plate
602 Perforated Plate
604 End cover plate
605 Perforations on inlet tube
703 Perforations on outlet tube
704 Internal ribs on outlet
705 Cone shaped cup
706 Solid pipe
801 Outlet pipe on Pressure relief valve
802 Internal tube on pressure control valve
803 Spring on pressure relief valve
804 First solid plate
805 Second solid plate
806 washer
807 Third plate
808 head
809 Valve adjustment rod
810 Tightening nut on pressure relief valve
811 Lock nut on pressure relief valve
812 Exhaust port
901 Control rod
902 spring
903 Mounting bracket
904 End stopper
905 Intermediate stopper
906 Movable plate
907 Fixed plate
908 Threaded portion
909 Washer on control rod
910 Tightening nut on pressure control valve
911 lock nut on pressure control valve
912 slot

The present disclosure relates to a muffler (101) of an automobile. More particularly  the disclosure relates to a muffler (101) for a heavy commercial vehicle.

In one embodiment of the disclosure at least one baffle plate is provided inside a chamber to reduce the noise of the exhaust gases. And the efficiency of the muffler (101) is varied by varying the number of the perforations provided on the baffle plate.

In the present disclosure  the muffler (101) is provided with expanding and contracting muffler body which contributes in reducing back pressure transmitted by the muffler (101) to the vehicle engine. And further the baffle plate placed at the predetermined location inside the chamber attenuates the sound produced by the vehicle exhaust.

In one embodiment of the present disclosure  the cross-sectional area of the muffler (101) is selected from group comprising but not limiting to circle  square  ellipse and rectangle and its combinations thereof. For example a muffler (101) may be constructed of circular or square cross-sectional channels by incorporating volumetric changes. And further the muffler (101) can also be provided with the combinations of the various cross-sections for achieving reduced back pressure of the engine exhaust.

FIGS.1- 5 illustrates schematic representation of muffler (101) in accordance with the present disclosure. The muffler (101) disclosed herein is a combination of inlet (103)  outlet (104)  a muffler body (102)  pressure control valve (108)  pressure relief valve (109) and at least one baffle plate. The muffler (101) consists of at least one baffle plate disposed inside the muffler body which bifurcate the muffler body into chambers. According to present disclosure there are two baffle plates which are disposed inside the muffler body  said baffle plates are first baffle plate (106) and second baffle plate (107). These baffle plate bifurcates the muffler body (102) into first chamber (113)  second chamber (114) and third chamber (115). The inlet (103) provided in the muffler (101) extends until the second chamber (114) such that the extension of the inlet inside the first chamber has perforation (605). A perforated plate (602) along with glass wool (112) layer is been placed at the end of the inlet (103). Further the first chamber (113) consists of a perforated inner jacket (105) which is concentrically covered by glass wool (112) and is aligned with outer jacket (111) of the muffler body (102). This arrangement is made to attenuate the noise produced inside the muffler (101). A second chamber (114) followed by the first chamber (113) forms the intermediate chamber. Further a third chamber (115) extends from the second chamber (114). The third chamber (115) consists of a pressure control valve (108) which is provided on the upper portion of the chamber (115). The pressure control valve (108) opens and closes one of the holes provided on the baffle plate. When the pressure in the second chamber (114) exceeds a predetermined value the pressure control valve (108) opens the hole (303) in the second baffle plate (107) creating an extra area for the exhaust to pass through. By doing this the engine performance can be optimized. The pressure control valve (108) having a control rod (901) is mounted between a mounting bracket (903) and an end plate (110). Said control rod (901) is fastened to the third chamber (115) by a tightening nut (910) and a lock nut (911). A washer (909) is provided between the end plate (110) and the tightening nut (910). An outlet (104) follows the third chamber (115) which is provided with an extended portion inside the third chamber. Perforations are provided throughout the extended portion of the outlet (104). And said extended portion is covered by a layer of glass wool (112) and is enclosed by a solid pipe (706) from outer side. The exhaust gas is finally released to atmosphere through the outlet (104).

FIGS 6a and 6b illustrate schematic representation of the inlet (103) wherein said inlet (103) is a tubular structure. The inlet (103) of the muffler (101) extends up to a predetermined distance into the second chamber (114). A perforated plate (603) along with glass wool (112) layer is been placed at the end of the inlet (103). An end cover plate (604) at extreme end of the inlet (103) covers the glass wool (112) layer. The number of perforations in the perforated plate (602) ranges from 15 to 30 whose diameter ranges from 5mm to 9mm. This glass wool (112) and perforated plate (602) assembly will absorb the impact of acoustic pressure which is directly coming from the engine. The extended portion of the inlet (103) consists of perforations (605) which are disposed on its body. The perforations on the extended portion of the inlet consist of holes of 9mm diameter and the number of perforation (605) on the inlet varies from 160 to 190. However  the number of perforations can be varied based on the requirement and size of extended portion of the inlet (103). Exhaust gases from vehicle engine enters into muffler through the inlet (103) and further expands inside the first chamber and is expelled to adjacent chamber.

The details of the outlet (104) are shown in figs 7a & 7b. The outlet of the muffler (104) is of diameter range from 75mm to 90mm and thickness range 1mm to 2mm. The outlet (104) is extended inside the third chamber (115). The extended outlet portion is a perforated throughout its body wherein the perforations (703) are of diameter of range 5 mm to 9mm and the number of perforations is about 230. The extended portion of the outlet (104) is covered by a solid pipe (706) with a layer of glass wool (112) in-between to attenuate the noise. The solid pipe (706) covering the outlet tube (104) is of diameter range 100mm to 115mm. A cone shaped cup (705) is welded at the front end of the outlet (104) for creating easy passage way for exhaust. The outlet (104) is welded to muffler body (102) using equally spaced three ribs (704) which are welded to the end plate (110) of the muffler body.

The assembly of pressure relief valve (109) is shown in figs 8a  8b and 8c. If pressure inside the chambers exceeds the predetermined limits due to blockage  the pressure relief valve (109) deviates the exhaust gas directly to the atmosphere through outlet pipe of the valve (109) to maintain the engine performance. Outlet pipe (801) of the pressure relief valve (109) is of diameter range 18mm to 25 mm and length ranging from 30 mm to 35 mm and thickness 1mm to 2mm. An internal rib (802) welded inside the outlet pipe (801) has an outer diameter of 16.8mm and inner diameter of 14mm. A spring (803) of stiffness ranging from 3 to 4 kg/square centimeter is welded between a first plate and a solid plate. The stiffness of the spring (803) can be adjusted as per requirement. The first plate (804) is of 1.6 mm thickness and diameter 16.8 mm. The second plate (805) is of thickness 1.6 mm and diameter 16.8 mm. Further the second plate is welded with a valve adjustment rod (809) whose diameter is 10 mm. At the head (808) of the valve adjustment rod (809) a slot (813) of 1mm width and 1 mm thick is provided for adjusting the valve (109) with the help of a screw driver. A third plate (807) of outer diameter 20mm and inner diameter 10 mm is welded to the top end of outlet pipe (801). A washer (806) of outer diameter 15mm and inner diameter 10mm is placed in between the third plate and a tightening nut (810). The tightening nut (810) along with a lock nut (811) is fastened to the valve adjustment rod (809). The internal ribs (802) are welded to the outlet pipe (801) at distance of 15mm from said third plate. An exhaust port (812) of diameter 5mm is situated on the outlet pipe (801) at a distance of 10 mm from third plate (806).

A pressure control valve (108) is shown in figs 9a-9d. The pressure control valve (108) consists of a control rod (901) whose diameter is 10mm and length ranges from 330 mm to 360 mm. A spring (902) of stiffness 1 to 2 kg/square centimeter is welded between a movable plate (906) and a fixed plate (907). Both the movable plate (906) and the fixed plate (907) have similar dimensions with thickness of 1.6mm with outer diameter 20mm and inner diameter 10mm. The fixed plate (907) is welded to the control rod (901). A mounting bracket (903) along with plurality of legs is welded to the second baffle plate (107). The mounting bracket (903) has a central hole of diameter 10mm. The control rod (901) is mounted between the mounting bracket (903) and an end plate (110). An end stopper (904) is provided on first end of the control rod (901) which is of square section (2mmx2mm) and length of 15mm. An intermediate stopper (905) of same cross-section as that of the end stopper (904) and length of 12 to 14mm is placed at 10 to 15 mm from end stopper (904) towards the third hole (303) on the second baffle plate (107). A tightening nut (910) and lock nut (911) are mounted on a threaded portion (908) on the second end of the control rod (901) to hold the control rod (901) in the set position. A washer plate (909) of inner diameter 10mm and outer diameter 15mm is placed between the end plate (110) and a tightening nut (910). A slot (912) of 1 mm width and 2mm depth is formed on the second end of the control road (901) to operate the control rod (901) by screw driver.
At minimum and medium engine rpm the exhaust gas flow rate is low  the pressure control valve (108) remains closed but at higher rpm the exhaust flow rate is very high hence the pressure control valve (108) opens to increase the opening area and maintain the back pressure at predetermined limit. There is also a provision to open the third hole (303) on the second baffle plate (107) totally  after predetermined limit of expansion of the spring (902) the stopper makes contact with the movable plate (906) and starts moving in the right direction to fully open the third hole (303) on the second baffle plate (107). Diameter of the third hole (303) is more than the intermediate stopper (905).

The second baffle plate (107) with plurality of openings is shown in fig-10. The third hole (303) on the second baffle plate (107) is covered by the movable plate (906) which is pressed against the third hole (303) by the spring (902) force acting on the movable plate (906). The movable plate (906) placed nearer to the vicinity of the third hole (303) in the second baffle plate (107) consists of a spring (902) which is compressed when the pressure inside the second chamber (114) exceeds the predetermined limit. The movable plate (906) is retracted to its initial position when the pressure inside the third chamber (115) falls below the predetermined limit.

In an alternative embodiment the arrangement of the mounting bracket (903) with plurality of legs along with the movable plate (906) and spring (902) can be altered by welding the mounting bracket (903) nearer to the vicinity of the third hole (303) in the second baffle plate (107) with incorporating the spring (902) within the space between the mounting bracket (903) and its legs. Here the spring (902) is compressed when the pressure inside the second chamber (114) exceeds the predetermined value. Also  the spring (902) is welded to the mounting bracket (903) such that the spring (902) moves within the mounting bracket (903). Here the movable plate (906) may be mounted with partial opened position or completely closed position or fully opened position and displaces based on the pressure on the movable plate (906).

The muffler (101) volume is low  low cost and light design muffler (101) for an automotive vehicle compared to some traditional prior-art muffler (101) keeping the performance unchanged.

The foregoing description provides specific embodiments of the present disclosure. It should be appreciated that these embodiment are described for purpose of illustration only  and that numerous other alterations and modifications may be practiced by those skilled in the art without departing from the spirit and scope of the invention. It is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or the equivalents thereof.
Equivalents

With respect to the use of substantially any plural and/or singular terms herein  those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.

It will be understood by those within the art that  in general  terms used herein  and especially in the appended claims (e.g.  bodies of the appended claims) are generally intended as “open” terms (e.g.  the term “including” should be interpreted as “including but not limited to ” the term “having” should be interpreted as “having at least ” the term “includes” should be interpreted as “includes but is not limited to ” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended  such an intent will be explicitly recited in the claim  and in the absence of such recitation no such intent is present. For example  as an aid to understanding  the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However  the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation  even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g.  “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition  even if a specific number of an introduced claim recitation is explicitly recited  those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g.  the bare recitation of “two recitations ” without other modifiers  typically means at least two recitations  or two or more recitations). Furthermore  in those instances where a convention analogous to “at least one of A  B  and C  etc.” is used  in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g.  “a system having at least one of A  B  and C” would include but not be limited to systems that have A alone  B alone  C alone  A and B together  A and C together  B and C together  and/or A  B  and C together  etc.). In those instances where a convention analogous to “at least one of A  B  or C  etc.” is used  in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g.  “a system having at least one of A  B  or C” would include but not be limited to systems that have A alone  B alone  C alone  A and B together  A and C together  B and C together  and/or A  B  and C together  etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms  whether in the description  claims  or drawings  should be understood to contemplate the possibilities of including one of the terms  either of the terms  or both terms. For example  the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.”

While various aspects and embodiments have been disclosed herein  other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting  with the true scope and spirit being indicated by the following claims.

We claim:

1. A muffler (101) comprising:
A muffler (101) body having at least one inlet (103) and at least one outlet (104) of predetermined shape on either ends;
at least one baffle plate having plurality of holes placed inside the muffler (101) at a predetermined location to bifurcate the muffler body (102) into plurality of chambers; and
at least one pressure control valve (108) placed inside at least one of the chamber  wherein said pressure control valve (108) comprises:
a control rod (901) placed axially inside the chambers; and
a movable plate (906) mounted on the control rod (901) at vicinity of at least one of plurality of holes of the baffle plate connecting adjacent chambers such that the movable plate (906) is displaced when pressure inside the adjacent chamber exceeds a predetermined limit  wherein the predetermined limit is set by adjusting the control rod (901).

2. The muffler (101) as claimed in claim 1  wherein the pressure control valve (108) consists a spring (803) of predetermined stiffness welded between the movable plate (906) and a fixed plate (907) and is mounted concentrically at first end of the control rod (901)  wherein the fixed plate (907) is welded to the control rod (901).

3. The muffler (101) as claimed in claim 2  wherein the spring (803) compresses and expands based on the pressure in the adjacent chamber.

4. The muffler (101) as claimed in claim 1  wherein the control rod (901) is adjusted by an adjusting mechanism  wherein said adjusting mechanism comprises:
a mounting bracket (903) having plurality of legs welded to the baffle plate to support the control rod (901) on first end 
at least one stopper (904) provided on the first end of the control rod to limit movement of the control rod (901)  wherein the mounting bracket (903) is mounted between the stopper and the baffle plate 
a threaded portion (908) formed on second end of the control rod (901)  and
a slot (912) on the second end of the control rod (901) to displace the control rod (901) for adjusting the control rod  wherein the slot (912) is operated externally to the chamber.

5. The muffler (101) as claimed in claim 1  wherein the chambers formed are first chamber (113)  second chamber (114) and third chamber (115).

6. The muffler (101) as claimed in claim 1  wherein the inlet (103) and the outlet (104) extends inside the first chamber (113) and third chamber (115) respectively upto a predetermined distance.

7. The muffler (101) as claimed in claim 4  wherein the extended portion of the inlet and the outlet are perforated.

8. The muffler (101) as claimed in claim 1  wherein a perforated jacket (105) is provided in the first chamber (113) such that the perforated jacket (105) is aligned to outer jacket (111) of the first chamber (113) with glass wool (112) concentrically between the perforated jacket (105) and the outer jacket (111) for attenuating sound.

9. The muffler (101) as claimed in claim 1  wherein the outlet tube (104) is surrounded by glass wool (112) and a solid pipe (706).

10. A method of controlling back pressure of a muffler (101) comprises 

displacing a movable plate (906) mounted on a control rod (901) placed in a chamber at vicinity of at least one of plurality of holes of a baffle plate placed inside muffler body (102) to release exhaust gases when pressure inside the adjacent chamber exceeds a predetermined limit  wherein the predetermined limit is set by adjusting the control rod (901).

11. The method as claimed in claim 11  wherein the spring (803) is compressed when the pressure in the adjacent chamber exceeds predetermined limit and the spring (803) moves back to expanded/initial position when the pressure in the adjacent chamber falls below the predetermined limit.

12. The method of controlling back pressure as claimed in claim 11  wherein the control rod (901) is adjusted by an adjusting mechanism to control the back pressure  wherein said adjusting mechanism comprises acts of:
welding a mounting bracket (903) having plurality of legs to the baffle plate to support the control rod (901) on first end 
providing at least one stopper on the first end of the control rod to limit movement of the control rod  wherein the mounting bracket is mounted between the stopper and the baffle plate  
forming a threaded portion (908) on second end of the control rod (901)  and
displacing a slot (912) on the second end of the control rod (901) for adjusting the control rod  wherein the slot (912) is operated externally to the chamber.