FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, rule 13]
"AN EXHAUST MUFFLER"
NAME AND ADDRESS OF THE APPLICANT:
TATA MOTORS LIMITED, an Indian company having its registered office at Bombay house, 24 Homi Mody Street, Hutatma Chowk, Mumbai 400 001, Maharashtra, INDIA.
Nationality: Indian
The following specification particularly describes the invention and the manner in which it is to be performed.

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
The prior-art mufflers are typically a combination of reaction and absorption elements. These are costlier, have more weight, difficult to manufacture and also hazardous for environment because they have glass wool.
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. Further, existing conventional systems provides exhaust muffler with absorbing material which are hazardous to health.
Hence, there exist needs to develop a muffler with less weight, less number of components, easy to manufacture and not hazardous to environment

STATEMENT OF THE DISCLOSURE
Accordingly, the disclosure provides a muffler (1), comprising at least one stepped inlet (2) and at least one stepped outlet (3) of predetermined shape provided on either ends of the muffler (1), wherein the stepped inlet (2) is classified into an inlet section (2a) and a passage way (2b) and the stepped outlet (3) is classified into an outlet section (3a) and a passage way (3b) and cross-section of said passage ways (2b. 3b) are larger than that of the inlet section (2a) and outlet section (3a) respectively. A chamber (4) of predetermined shape having larger cross-sectional area than that of the stepped inlet (2) and the stepped outlet (3) is placed axially in between the stepped inlet (2) and the stepped outlet (3). wherein inlet of the chamber (4) has shape selected from at least one of stepped and diverging, and outlet of the chamber (4) has shape selected from at least one of stepped and converging, and at least one perforated plate (5) is placed axially inside the chamber (4) at a predetermined location.
A method of assembling a muffler (1) is disclosed as another aspect of the present disclosure. The method comprises acts of connecting a stepped inlet (2) and a stepped outlet (3) to a chamber (4) on its either sides. And placing at least one perforated plate (5) axially inside the chamber (4) at predetermined location.
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 (1), comprising at least one stepped inlet (2) and at least one stepped outlet (3) of predetermined shape provided on either ends of the muffler (1), wherein the stepped inlet (2) is classified into an inlet section (2a) and a passage way (2b) and the stepped outlet (3) is classified into an outlet section (3a) and a passage way (3b) and cross-section of said passage ways (2b, 3b) are larger than that of the inlet section (2a) and outlet section (3a) respectively. A chamber (4) of predetermined shape having larger cross-sectional area than that of the stepped inlet

(2) and the stepped outlet (3) is placed axially in between the stepped inlet (2) and the stepped outlet (3), wherein inlet of the chamber (4) has shape selected from at least one of stepped and diverging, and outlet of the chamber (4) has shape selected from at least one of stepped and converging, and at least one perforated plate (5) is placed axially inside the chamber (4) at a predetermined location.
In one embodiment of the present disclosure the cross-sectional area of the muffler (1) is selected from group comprising circle, square, ellipse, rectangle and its combinations thereof.
In one embodiment of the present disclosure the perforations (6) are in concentric circular with predetermined number of perforations on each concentric circle.
In one embodiment of the present disclosure the perforations are having diameter ranging from 3 to 9mm.
In one embodiment of the present disclosure provides a method of assembling a muffler (1), comprising acts of connecting a stepped inlet (2) and a stepped outlet (3) of to a chamber (4) on its either sides. And placing at least one perforated plate (5) axially inside the chamber (4) at predetermined location.
In one embodiment of the present disclosure the stepped inlet (2) is formed by connecting an inlet section (2a) and a passage way (2b), and wherein the cross-section of the passage way (2b) is larger than that of inlet section (2a).
In one embodiment of the present disclosure the stepped outlet (3) is formed by connecting an outlet section (3 a) and a passage way (3b), and wherein the cross-section of the passage way (3b) is larger than that of outlet section (3a).
In one embodiment of the present disclosure the perforated plate (5) is joined to the chamber (4) along its periphery.
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:
FIGS, 1a- 1d illustrate schematic representation of the muffler viewed from front according to the disclosure.
FIG. 2 illustrates schematic representation of the muffler viewed from the inlet of the muffler according to the disclosure.
FIG. 3 illustrates schematic representation of the perforated plate with perforations as shown by circular central line according to the disclosure.
FIG. 4 illustrates Isometric wire mesh view 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.
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
1 Muffler
2 Stepped inlet
2a Inlet section
2b Passage way
3 Stepped outlet
3a Outlet section
3b Passage way
4 Chamber
5 Perforated plate
6 Perforation
7 Tapered Portion
The present disclosure relates to a muffler of an automobile. More particularly, the disclosure relates to a muffler for a heavy commercial vehicle.
The present disclosure is of simple reaction type muffler having less weight, uses less number of components, easy to manufacture and not hazardous to environment because it does not use glass wool. Over and above that, the bell mouth shape portion

of the design, the backpressure is kept under control thereby maintaining the engine performance.
In one embodiment of the present disclosure, the perforated plate is placed inside the chamber (4) of the muffler.
In one embodiment of the disclosure multiple perforated plates are provided inside the chamber to reduce the noise of the exhaust gases. And the efficiency of the muffler is varied by varying the number of the perforations provided on the perforated plate.
In one embodiment of the present disclosure, components (2a. 2b, 4, 3a and 3b) of the muffler (1) are co-axial.
Fig. 1a illustrates the present disclosure; the inlet of the muffler is a stepped inlet (2) formed by two sections i.e. an inlet section (2a) and a passage way (2b). The passage way (2b) has a larger diameter compared to the inlet section (2a). And further the outlet of the muffler is also a stepped outlet formed by passage way (3a) and outlet section (3b). A chamber (4) having gradual reduction in its cross-section towards the stepped outlet (3) referred as tapered portion is placed in between the stepped inlet (2) and the stepped outlet (3). A perforated plate (5) is placed axially inside the chamber (4) for sound attenuation.
Fig. lb in one exemplary embodiment discloses the inlet of the muffler (1) having a stepped inlet (2) formed by two sections i.e. an inlet section (2a) and a passage way (2b). And further the outlet of the muffler is also a stepped outlet formed by passage way (3a) and outlet section (3b). Further, an inlet having gradual cross-sectional increase followed by a passage and an outlet having gradual cross-sectional decrease referred as chamber (4) is placed in between the stepped inlet (2) and the stepped outlet (3). A perforated plate (5) is placed axially inside the chamber (4) for sound attenuation.
Fig. lc in one exemplary embodiment discloses the inlet of the muffler (1) which is a stepped inlet (2) formed by two sections i.e. an inlet section (2a) and a passage way (2b). And the outlet of the muffler is also a stepped outlet (3) formed by passage way (3a) and outlet section (3b). A chamber (4) formed with a gradual cross-sectional increase at its inlet referred as tapered portion (7) is placed in between the stepped

inlet (2) and the stepped outlet (3). A perforated plate (5) is placed axially inside the chamber (4) for sound attenuation.
Fig. 1d in one exemplary embodiment discloses the inlet of the muffler (1) and the outlet of the muffler (1) which are made up of stepped inlet (2) and stepped outlet (3). A chamber (4) is placed in between the stepped inlet (2) and the stepped outlet (3). A perforated plate (5) is placed axially inside the chamber (4) for sound attenuation.
In one embodiment of the present disclosure, the cross-sectional area of the muffler (1) is selected from group comprising circle, square, ellipse and rectangle and its combinations thereof. For example a muffler may be constructed of circular or square cross-sectional channels by incorporating volumetric changes. Further the muffler can also be provided with the combinations of the various cross-sections for achieving reduced back pressure of the engine exhaust.
FIGS.1, 2, 3 and 4, illustrates schematic representation of muffler (1) in accordance with the present disclosure. The muffler (1) disclosed here is a combination of stepped inlet (2), stepped outlet (3), a chamber (4) and perforated plate (5). The muffler (1) is made up of an inlet section (2a) which is a channel having a diameter about 78 mm. The inlet section (2a) is followed by a passage way (2b) with a uniform circular section having diameter of about 106 mm and has a length of about 75 mm. Both the inlet section (2a) and the passage way (2b) together are referred as stepped inlet (2). A uniform circular chamber (4) having diameter of about 197 mm and length of about 200 mm is attached to the passage way (2b). The chamber (4) has a circular perforated plate (5) placed at a distance of about 150 mm from the uniform circular section passage way (2b). Each perforation (6) is a hole having a diameter of about 6.5 mm. The perforation (6) of the perforated plate (5) is configured into a concentric circular pattern. The perforated plate (5) acts as a noise attenuator.
A section after chamber (4) is tapered portions (7) having start diameter about 200 mm and end diameters as about 106 mm respectively. This reduction in diameter happens over a length of about 75 mm. The tapered portion (7) in turn reduces the back pressure of the exhaust gases before passing it on to the vehicle engine. The next section in line is another uniform circular section channel (3b) referred as passage way having diameter of about 106 mm and length of about 75 mm. The exhaust gas

passes through a uniform circular sectional channel referred as outlet section (3a) whose diameter is about 78 mm. All the components are coaxial.
In one embodiment, the distance between the central hole and the 1st concentric circle is about 10 mm. Also the distance between 9th concentric circle and the outer diameter of the perforated plate is about 10 mm. The distance between any two concentric circles of the concentric circular pattern of holes is about 10 mm. The number of perforations, in 1st concentric circle is 5, in 2nd concentric circle is 10. in 3rd concentric circle is 15, in 4th concentric circle is 24, in 5th concentric circle is 29, in 6th concentric circle is 33, in 7th concentric circle is 39. in 8th concentric circle is 44 and in 9th concentric circle is 50, and the total number of perforation is 250. However, number of perforations in each concentric circle can be varied based on the requirement. The number presented here for the purpose of illustrative and its not a limitation on the invention.
Advantages:
The muffler volume is low, low cost and light design muffler for an automotive
vehicle compared to some traditional prior-art muffler keeping the performance
unchanged.

We claim:
1. An exhaust muffler (1) comprising:
at least one stepped inlet (2) and at least one stepped outlet (3) of predetermined shape provided on either ends of the muffler (1), wherein the stepped inlet (2) is classified into an inlet section (2a) and a passage way (2b) and the stepped outlet (3) is classified into an outlet section (3a) and a passage way (3b); wherein cross-section of said passage ways (2b, 3b) are larger than that of the inlet section (2a) and outlet section (3a) respectively;
a chamber (4) of predetermined shape having larger cross-sectional area than that of the stepped inlet (2) and the stepped outlet (3) placed axially in between the stepped inlet (2) and the stepped outlet (3), wherein inlet of the chamber (4) has shape selected from at least one of stepped and diverging, and outlet of the chamber (4) has shape selected from at least one of stepped and converging;
at least one perforated plate (5) placed axially inside the chamber (4) at a predetermined location.
2. The muffler (1) as claimed in claim 1. wherein cross-sectional shape of the stepped inlet (2) and the stepped outlet (5), and the chamber (4) is selected from group comprising circle, square, ellipse and rectangle and its combinations thereof.
3. The muffler (1) as claimed in claim 1, wherein the perforated plate (5) is made up of plurality of concentric circle with predetermined number of perforations on each concentric circle.
4. The muffler (1) as claimed in claim 1, wherein the perforations (8) are having diameter ranging from 3 to 9 mm.
5. A method of assembling muffler (1), comprising:
connecting a stepped inlet (2) and a stepped outlet (3) to a chamber (4) on its either sides; and
placing at least one perforated plate (5) axially inside the chamber (4) at predetermined location.
6. The method of assembling muffler (1) as claimed in claim 5, wherein the stepped
inlet (2) is formed by connecting an inlet section (2a) and a passage way (2b). and

wherein the cross-section of the passage way (2b) is larger than that of inlet section (2a).
7. The method of assembling muffler (1) as claimed in claim 5, wherein the stepped outlet (3) is formed by connecting an outlet section (3a) and a passage way (3b), and wherein the cross-section of the passage way (3b) is larger than that of outlet section (3 a).
8. The method as claimed in claim 5, wherein said perforated plate (5) is joined to the chamber (4) along its periphery.
9. A muffler (1) and a method of assembling are substantially as herein above described and as illustrated in accompanying drawings.