Field of the Invention

The present invention relates to a muffler for automotive vehicles and the muffler for automotive vehicles reduces noise and meets the BSIII emission norms.

Background of the Invention

The conventional automotive mufflers come in all different shapes, styles and size depending on the desired application. Generally automotive mufflers usually have a circular or elliptical cross section. A circular shaped cross section is best suited in a vehicle as it delays the onset of higher order modes. These types of mufflers have been widely tested and the general observations from such tests are described. The present type mufflers which employ the principle of both reflective and absorptive techniques to reduce the noise level gas of automotive vehicles to a pre-determined range with additionally accommodate various after treatment device systems.

Commercial vehicles are the major contributors for noise pollution by automobiles. The main contributor of noise in a commercial vehicle, per se, is the exhaust system. The control of noise from the exhaust system depends on the design of the muffler, the layout of the exhaust system, the piping and also the after treatment devices. However, the specific focus is towards the design of the muffler. Design of mufflers is a complex function that affects the noise characteristics and the fuel efficiency of the vehicle. So, a good design of the muffler should give the best noise reduction and offer optimum back pressure for the engine. Moreover, for a given internal configuration, mufflers have to work for a broad range of engine speed. Mufflers can have a number of elements inside which need to be chosen as per the level of attenuation required and recommended engine back pressure, this involves a lot of iterations of physical testing for each of the prototypes. Any muffler is qualified by the amount of insertion loss (IL) that takes place within the muffler. Insertion loss can be defined as the difference in sound pressure levels (SPL) at the exhaust outlet, with and without the muffler. Based on the required insertion loss, mufflers with different internal configurations can be designed and tested for muffled noise spectrum and vehicle noise.

In addition to these, there is a need for exhaust systems to meet stricter emission norms. In such cases when the migration from BSIII to BSIV is effected, there is a need to have additional after-treatment devices. The common ones used are SCR (selective catalytic reduction) and DOC/POC (oxidation catalysts in tandem with EGR-exhaust gas recirculation). When these are brought in to effect, we need to have additional space to package these in separate enclosures. All this results in addition of more brackets, lesser space for packaging, higher costs and need for more maintenance. Also there is always the risk of pilferage of the after treatment device. The 120IL engine makes use of an inline fuel injection pump. The raw engine out emissions is BSII compliant only. In order to achieve BSIII emissions there is a need of an additional exhaust after treatment device.

Summary of the Invention

In order to solve the above-described problem, the present invention provides a muffler for automotive vehicles. The advantages of the muffler for automotive vehicles are as follows:

a) Consistent performance
b) Reduced cost
c) Reduced weight
d) Decreased variety
e) Ease in vehicle assembly
f) Reduced components assembly time
g) To meet BSIII emission norms

The object of the present invention is to provide a muffler for automotive vehicles providing reduced noise generation and offer optimum back pressure for the internal combustion engine, which in turn lead to optimum fuel efficiency of the vehicles.

A further object of the present invention is to provide a muffler for automotive vehicles having integrated diesel oxidation catalyst (DOC) within the silencer assembly which reduces the total particulate matter in the emissions thereby helping in achieving BSIII norms.

Another object of the present invention is to provide a muffler for automotive vehicles having a DOC coated with precious metal like platinum which aids in the oxidation process. The NOx in the emission is converted to N2 and 02 and this in turn helps in oxidizing the unburnt hydrocarbons or total particulate matter.

Yet a further object of the present invention is to provide a muffler for automotive vehicles which blends the performance characteristics of the exhaust system for automotive vehicles.
Yet another object of the present invention is to provide a muffler for automotive vehicles which is simple in construction and less costly.

Accordingly, the present invention provides a muffler for automotive vehicles connected at rear end of the inlet pipe assembly extending from an internal combustion engine of automotive vehicles and an outlet pipe assembly connected at rear end of the muffler so that the treated exhaust gases from the muffler flows to the atmosphere, wherein the muffler comprising: an inlet perforated pipe for connecting the inlet pipe assembly and the muffler; a first end cover having a hole is mounted on the first end of a jacket; a jacket for enclosing all the components of the muffler; an end plug joined at one end of the inlet perforated pipe for serving as a reflective wall on which the sound waves in the exhaust gases get reflected and are cancelled out by means of destructive interference; a baffle having a hole for supporting the DOC unit and preventing the DOC unit from mechanical damage by absorbing all the vibrations; a DOC unit for reducing the particulate emissions, noise level by virtue of wave cancellation of frequencies and pressure energy; a perforated baffle for serving as opening for gases to expand in the region between the baffle and perforated baffle; two perforated baffles for guiding the inlet perforated pipe and the outlet perforated pipe by means of the hole at the center of the perforated baffles; an outlet perforated pipe having set of perforations for reducing noise by cancelling out frequencies when the gases pass over the perforations; a second end cover having a hole mounted on the second end of the jacket for serving as a support for the perforated outlet pipe and for directing the exhaust gases out of the muffler; an exponential connector fixed to the free end of the outlet perforated pipe; and glasswool spread across the whole of the region around the perforated outlet pipe for absorbing the sound waves.

The jacket is divided into five chambers with the help of the baffles, respectively. The inlet perforated pipe is inserted from the first end cover and extends up to the second chamber through the hole of the perforated baffle. The jacket supports the baffles and prevents exhaust gases from leaking out. The end plug directs the gases to pass through the perforations in the inlet perforated pipe and subsequently through the perforations in the baffle resulting in noise attenuation. The DOC unit is fixed on the baffle on the second chamber and passes perforated baffle on the third chamber and end with fourth chamber. The DOC unit is placed equal distance on the second chamber and third chamber. The outlet perforated pipe is inserted from the hole of the perforated baffle on fourth chamber and passes through the second end cover. The distance from exponential connecter 11 on the perforated outlet pipe 09 which is fixed on fourth chamber D is 80mm. An exhaust system having a muffler, comprising a inlet pipe assembly connected at one end of the muffler so that exhaust gases from the internal combustion engine flows through the inlet pipe assembly to the muffler, and outlet pipe assembly connected at other end of the muffler so that the treated exhaust gases from the muffler flows to the atmosphere.

Brief Description of the Accompanying Drawings

The advantages and features of the invention will become more clearly apparent from the following description which refers to the accompanying drawings given as non-restrictive examples only and in which:

Figure 1 illustrates the perspective view of the exhaust system for automotive vehicle having the muffler of the present invention; and

Figure 2 demonstrates the front view of the muffler for automotive vehicles according to the invention.

Figure 3 show the Uniformity Index Benefit.

Detailed Description of the Preferred Embodiments

Referring to Figure 1, the exhaust system X for automotive vehicle of the present invention comprises an inlet pipe assembly W, a muffler Y and an outlet pipe assembly Z. The exhaust gases from the internal combustion engine flows through the inlet pipe assembly W and arrive at the muffler Y. Once the gases enter into the muffler Y, the gases are treated for meeting BSIII emissions norms and noise reduction by means of features incorporated inside the muffler. The gases then exit through the outlet pipe assembly Z.

Referring to Figure 2, the muffler Y of the present invention comprises a jacket 03 is the outer shell which encloses all the components of the muffler Y and performs the function of supporting the baffles 8, 5, 7, 8 and preventing exhaust gases from leaking out. The jacket 03 is covered at both end by first end cover 02 and second end cover 10 having a holes. The jacket 03 is divided into five chambers A, B, C, D & E with the help of the baffles 08, 05,07, 08, respectively. Two perforated baffles 08 are used to guide the inlet perforated pipe 01 and the outlet perforated pipe 09 by means of the hole at the center of the perforated baffles 08. The end plug 04 is fixed at one end of the inlet perforated pipe 01. The inlet perforated pipe 01 is inserted from the first end cover 02 and extends up to the second chamber B through the hole of the perforated baffle 08. A portion of the inlet perforated pipe 01 which is placed in the second chamber B comprises one set of perforations 12 of predetermined size to kill certain frequencies when it passes through the perforations. Each rows of perforations 12 are staggered compared to adjacent row of perforations. In a preferred embodiment, the diameter of the perforations 12 is about 6mm and the pitch distance between corresponding points of consecutive rows is about 12mm. For first chamber A the inlet perforated pipe 01 is having about 4 rows of the perforation 12 with twenty perforations per row. The inlet perforated pipe 01 which extend into the second chamber B is having about seven rows of the perforations 12 with twenty perforations per row. The inlet perforated pipe 01 could extend into the second chamber B for 60 to 65mm, preferably 63mm.

The DOC unit 06 is fixed on the baffle 05 on the second chamber B and passes perforated baffle 07 on the third chamber C and end with fourth chamber D. DOC unit 06 is placed equal distance on the second chamber B and third chamber C. In the DOC unit 06, the material Cordierite has been used with cell density of 300 to 400cpsi (cell per square inch). The diameter of the cell is 241mm and length is 150mm.

The outlet perforated pipe 09 is inserted from the hole of the perforated baffle 08 on fourth chamber D and passes through the second end cover 10 for directing the exhaust gases out of the muffler Y. The perforated outlet pipe 09 comprises set of perforations to kill certain frequencies. Each row of perforations are staggered compared to adjacent row of perforations for a given set. Preferably, the diameter of the perforation can be 2.8mm and the pitch can be about 5.6mm. The perforation contains 34 rows and 48 holes per row. The perforated outlet pipe 09 is fixed between the perforated baffle 08 and second end cover 10 at the distance around from 210mm to 218mm, preferably 215mm. The exponential connector 11 is fixed to the free end of the outlet perforated pipe 09 which converge to about 73mm outer diameter at one end with a width of about 15mm. The distance from exponential connecter 11 on the perforated outlet pipe 09 which is fixed on fourth chamber D is 80mm. The glasswool 12 has spreader across the whole of the region around the perforated outlet pipe 09 and inside the fifth chamber E.

In a preferred embodiment, the five chambers A, B, C, D & E of the jacket 03 could be having specific dimensions of 117mm, 169mm, 150mm, 180mm and 215mm. The free holes of the two perforated baffles 08 could be preferably 3.8mm with 15% open area of the total surface. These holes act as an acoustic element. The shape of the jacket 03 is preferably constructed from a plane sheet with ends of overlapped and welded across the whole length or crimped across the whole length.

The exhaust system X consists of an inlet pipe assembly W, a muffler Y, and an outlet pipe assembly Z through which exhaust gases flow from the internal combustion internal combustion engine and into the atmosphere.

The inlet pipe assembly W connects the internal combustion engine to the muffler Y through which exhaust gases flow from the internal combustion engine to the muffler Y.

The muffler Y is an envelope which consists of the elements assisting in reducing noise and also
emissions. The muffler Y is divided into four chambers A, B, C, D and E.

The outlet pipe assembly Z connects the muffler Y to the atmosphere through which exhaust gases which has been treated for noise and emissions flow from the muffler Y into the atmosphere.

The inlet perforated pipe 01 is for connecting the inlet pipe assembly (W) and the muffler (Y). The inlet perforated pipe 01 is inserted from the first end cover 02 and extends up to the second chamber B through the hole of the perforated baffle 08. A portion of the inlet perforated pipe 01 which is placed in the second chamber B comprises one set of 12 perforations of predetermined size to kill certain frequencies viz. 120Hz, 240Hz, 360Hz etc. when it passes through the perforations. Due to the plug all the exhaust gases are forced to pass through the radial perforations in the inlet perforated pipe 01. This gives benefits of noise reduction.

First end cover 02 having a hole is mounted on the first end of the jacket 03.

Jacket 03 is the outer shell which encloses all the components of the muffler Y and performs the function of supporting the baffles 8, 5, 7, 8 and preventing exhaust gases from leaking out.

The end plug 04 is fixed at one end of the inlet perforated pipe 01 which serves as a reflective wall on which the sound waves in the exhaust gases get reflected and are cancelled out by means of destructive interference. The presence of the plug also directs the gases to pass through the perforations in the inlet perforated pipe 01 and subsequently through the perforations in the baffle 08. Both these result in noise attenuation.

Baffle 05 having one large hole through which the DOC unit 06 is inserted and fixed. Function of the baffle 05 is to support the DOC unit 06 and prevent the DOC unit 06 from mechanical damage by absorbing all the vibrations the silencer is subject to.

The DOC unit 06 is fixed on the baffle 05 on the second chamber B and passes perforated baffle 07 on the third chamber C and end with fourth chamber D. DOC unit 06 is placed equal distance on the second chamber B and third chamber C. The DOC unit is provided with the intention of reducing the particulate emissions in the exhaust and helping the vehicle achieve BSIII emission norms. The construction of the DOC is in the form of a cellular structure with typical cell densities being in the range of 300 to 400cpsi (cells per square inch). When exhaust gases pass through these cells, there is a reduction in the noise level by virtue of wave cancellation of certain frequencies and also the loss of pressure energy. The DOC Integrated 120IL circular silencer is plug design which gives a great benefit of noise reduction over the other conventional silencers. Having already helped in achieving a better uniformity index which helps in increasing the emission reduction, it also gives the benefit of increased transmission losses. The end plug 04 is positioned such that it reflects the sound waves which get hit on it and results in a destructive interference through wave cancellation. This gives the primary noise reduction.

Perforated baffle 07 consists of 12 holes on its surface which basically serves as an opening for gases to expand in the region between the baffle 05 & perforated baffle 07. This expansion helps in reducing noise while at the same time forming a layer around the DOC unit 06 which results in more heat being retained inside the DOC unit 06.

Two perforated baffles 08 are used to guide the inlet perforated pipe 01 and the outlet perforated pipe 09 by means of the hole at the center of the perforated baffles 08. It also contains perforation of a specified diameter which help in attenuating certain frequency.

The outlet perforated pipe 09 is inserted from the hole of the perforated baffle 08 on fourth chamber D and passes through the second end cover 10 for directing the exhaust gases out of the muffler Y. The perforated outlet pipe 09 comprises set of perforations to kill certain frequencies. In addition to that, perforated outlet pipe 09 also helps in reducing noise by cancelling out certain frequencies when the gases pass over the perforations.

Second end cover 10 with a hole mounted on the second end of the jacket 03 serves as a support for the perforated outlet pipe 8. It also performs the function of preventing exhaust gases from leaking out.
The exponential connector 11 is fixed to the free end of the outlet perforated pipe 09. The position of the exponential connector which is halfway in the fourth chamber D between the DOC and the perforated baffle 07, and the design of the exponential connector in terms of dimensions is done keeping in mind the cancellation of certain frequencies of noise.

The glasswool 12 has spreader across the whole of the region around the perforated outlet pipe 09 and inside the fifth chamber E. The perforated outlet pipe 09 consists of several rows of perforations of a pre-determined size. When the exhaust gases pass through the perforated outlet pipe 09, the sound waves travelling in waves have their intensities reduced due to the fact that the higher amplitude waves pass through the perforations in the perforated outlet pipe 09 and are absorbed by the glasswool. The principle of noise reduction by this process is called absorptive/ reactive principle.

In the first chamber A, the exhaust gases enter through the inlet perforated pipe 01. The gases are forced to get reflected from the end plug 04 which blocks the gases from entering into second chamber B. The gases then pass through the perforations in the inlet perforated pipe 01 and into the first chamber. They then pass through the perforated baffle 08. There is attenuation of noise in the first chamber A by means of the reflection on the end plug 04 and passage of gases through the perforations in the inlet perforated pipe 01 and the perforated baffle 08.

In the second chamber B, some of the gases which are reflected on the end plug 04 pass through the perforations in the inlet perforated pipe 01 in the second chamber B. This provides additional noise reduction. These gases along with the gases that flow out through the perforated baffle 08 then pass through the second chamber B and into the DOC unit 06.

The third chamber C is formed by the two baffles (05 & 07) that support the DOC unit 06. Baffle 05 doesn't have any perforations on it and supports the DOC unit 06. Baffle 05 does not allow any gases to flow past it from the second chamber B other than through the DOC unit 06. The baffle 07 consists of perforations which basically serves as a guide for the gases to enter the region in the third chamber C around the DOC unit 06. This volume of gas helps in retaining heat inside the DOC unit 06 thereby helping the DOC unit 06 to reach the optimal performance.

The exhaust gases after passing through the DOC unit 06 arrive in to the fourth chamber D. Some amount of gases pass through the perforations in the baffle 07 for expansion. The gases then flow into the outlet perforated pipe 09 through the exponential connector 11. As the gases get are made to flow through the exponential connector 11, they lose energy and provide benefit of transmission loss.
The fifth chamber E is formed by the perforated baffle 08 and the second end cover 10. Inside the fifth chamber E, the glasswool 12 is spreader across the whole of the region around the perforated outlet pipe 09.

Referring to Figure 3, Uniformity index is the parameter which defines the efficiency or the percentage utilization of the surface area of the DOC. The higher the uniformity index, the higher will be the conversion rate of emission particle PM into harmless C02 and H20. The designs are shown in figure 3. A comparative study of the different concepts of flow designs using a CFD tool shows the benefit of uniformity index for the plugged design of silencer.

The results are tabulated below:
For the same catalyst used, a plugged design silencer gives a better emission reduction and also benefits by giving additional transmission losses.

Function of the circular muffler for automotive vehicles:
The exhaust gases from the engine flow through the inlet pipe assembly W and arrive at the muffler Y inlet.

Once the gases enter into the muffler Y, they get expanded through the inlet perforated pipe 01.

During this expansion, the gases lose energy and this helps reduce noise.
The gases pass through the inlet perforated pipe 01 and are reflected by the end plug 04 which leads to destructive interference by means of reflective principle of waves.

The gases then pass through the perforations in the inlet perforated pipe 01 and into the first chamber A and second chamber B.

The gases that enter the first chamber A are expanded through the perforations in on the inlet perforated pipe 01 and enter the second chamber B through the perforated baffle 08.

The gases then pass through the DOC unit 06 from the second chamber B. While passing through the DOC unit 06, the emission reduction function of reducing the total particulate matter is carried out. The exhaust gases that come out of the DOC unit 06 and into the fourth chamber D are BSIII compliant.
Some of the gases then pass through the perforations on the perforated baffle 07 and form a volume in the third chamber C around the DOC unit 06. This acts as an insulation for the DOC unit 06 helping it
retain heat resulting in quicker reactions.

The gases then flow through the exponential connector 11 from fourth chamber D and into the outlet perforated pipe 09. The gases flow through the outlet perforated pipe 09 and over the perforations on the utlet perforated pipe 09. The outlet perforated pipe 09 issurrounded by glasswool 12 in fifth chamber E. The glasswool 12 helps in reducing noise by means of absorptive principle. The gases then exit the muffler Y.

The gases flow through the tail pipe Z and into the atmosphere thereafter.

The gases at the outlet of the muffler Y are thus treated to meet emission norms and also, the noise is considerably reduced to meet the emission norms of BSIII.

Reflective Principle: The first two chambers (A & B) of the jacket 03 reflective muffler, the exhaust gas enters straight to the inlet perforated pipe 01 on second chamber B, end plug 04 is stop the straight flow of the exhaust gas. So it come across the first set of perforations on the inlet perforated pipe 01 to the chamber A and second set of perforations of inlet perforated pipe 01 to the second chamber B into the shell around the inlet perforated pipe 01, this phenomenon can be explained by the following points,
i) Expansion: The exhaust gas is initially present in the pipe, which is smaller diameter compared to the shell/jacket diameter. There is difference between the volume of the pipe & the volume of the shell giving rise to expansion of the gas into the larger volume space, this gives the benefit of transmission loss, ii) Pipe perforation: the perforations are the specific designs to kill certain frequencies during the passage of the exhaust gases over the perforations on the pipe. The thickness of the pipe also plays a role. This gives benefit of transmission loss, iii) During the hit on the end plug of the exhaust gas and it gets reflected resulting in reflected waves that cancel some of the incoming waves. This gives the benefit of transmission of transmission loss.

After the perforated inlet pipe 01, the exhaust gas enter the DOC unit, the catalyst interacts with the exhaust as it passes through the converter. The Catalyst causes the particulate to burn at normal exhaust temperatures and it burns the gaseous hydrocarbons and carbon monoxide emissions, and the lube oil, unburned fuel and carbon soot of the total particulate matter. The particulate removed exhaust gas is circulated in the fourth chamber D and some of the exhaust gas entering to the holes of the perforated baffle 07 and circulate in the third chamber C. During this circulation, they lose velocity and hence energy thereby reducing transmission loss.

Absorptive Principle: The exhaust gas that comes in through the perforated outlet pipe 09, flows over the surface of the perforated outlet pipe 09 and its perforations and blasts the glasswool 13 blanket that is wrapped around the perforated inlet pipe 01 perforations, resulting in attenuation of certain frequencies and spreading of the glasswool across the whole of the region around the perforation pipe. As the glasswool is packed such that it has filament thickness of the order of a few microns, there is a lot of surface contact between the exhaust gas escaping from the perforations and the filaments of the glasswool. This results in friction and conversion of acoustic energy into heat thereby helping in further transmission loss.

In addition to these, glasswool is also packaged in the embossed region of the end cover and a perforation plate is welded on it to prevent the glasswool from coming out. When the exhaust gases pass through these holes in the perforation plates, due to the surface contact, there is further loss of acoustic energy as heat.

Reference numerals:
X - Exhaust system;
W - Inlet pipe assembly;
Y - Muffler;
Z - Outlet pipe assembly;
1 - Inlet perforated pipe;
2 - First end cover;
3 - Jacket;
4 - End plug;
5 - Baffle;
6 - DOC unit;
7 - Perforated baffle;
8 - Two perforated baffles;
9 - Outlet perforated pipe;
10 - Second end cover;
11 - Exponential connector;
12 - Glasswool;

A - First chamber;

B - Second chamber;
C - Third chamber;
D - Fourth chamber;
E - Fifth chamber.

NVH Performance results:
Insertion loss test:
Insertion loss is a term used to define the effectiveness of a silencer/ exhaust system. The insertion loss of an exhaust system gives the indication of how much noise reduction of the engine is possible due to the silencer. The higher the insertion loss, the better it is from the noise perspective.

A comparative test of the invention with other silencers of older/ different concepts shows that the noise performance of the 120IL Circular advanced integrated muffler is much better showing a considerable improvement of 2.7dB over the previous/ existing silencer and almost 4dB over a proprietary silencer with an older design.

The below shown table gives a comparison of the tree silencers tested in the same conditions on the same vehicle in terms of insertion loss.

The overall insertion loss is better for the present invention over the entire range of engine speed. A graph showing the insertion loss curves of all the three silencers along with the unmuffled noise is given below.

■ The first graph shows the insertion loss comparison for the silencers in the wide open throttle condition.

■ The second graph shows a similar comparison in the pass-by noise condition.

In both the conditions, the insertion loss values of the present invention are consistently better than the other two concepts in fray.

INSERTION LOSS Overall Level - 3rd Gear WOT PBN Condition

INSERTION LOSS 6.0 Order - 3rd Gear Pass By Noise Condition

Though the present invention was shown and described with reference to the preferred embodiments, such are merely illustrative of the present invention and are not to be construed as limitation thereof and various modifications of the present invention will be apparent to those skilled in the art. Furthermore, all examples and conditional language recited herein are principally intended expressly to be only for pedagogical purposes to aid the reader in understanding the principles of the invention and the concepts contributed by the inventor(s) to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. It is therefore not intended that the present invention be limited to the disclosed embodiments or details thereof, and the present invention includes all variations and/or alternative embodiments within the spirit and scope of the present invention as defined by the appended claims:

WE CLAIM:

1. A muffler (Y) for automotive vehicles connected at rear end of the inlet pipe assembly (W) extending from an internal combustion engine of automotive vehicles and an outlet pipe assembly (Z) connected at rear end of the muffler (Y) so that the treated exhaust gases from the muffler (Y) flows to the atmosphere, wherein the muffler (Y) comprising:

an inlet perforated pipe (01) for connecting the inlet pipe assembly (W) and the muffler (Y);

a first end cover (02) having a hole is mounted on the first end of a jacket (03);

a jacket (03) for enclosing all the components of the muffler (Y);

an end plug (04) joined at one end of the inlet perforated pipe (01) for serving as a reflective wall on
which the sound waves in the exhaust gases get reflected and are cancelled out by means of destructive interference;

a baffle (05) having a hole for supporting the DOC unit 06 and preventing the DOC unit 06 from mechanical damage by absorbing all the vibrations;

a DOC unit (06) for reducing the particulate emissions, noise level by virtue of wave cancellation of frequencies and pressure energy;

a perforated baffle (07) for serving as opening for gases to expand in the region between the baffle (05) and perforated baffle (07);

two perforated baffles (08) for guiding the inlet perforated pipe (01) and the outlet perforated pipe (09) by means of the hole at the center of the perforated baffles (08);

an outlet perforated pipe (09) having set of perforations for reducing noise by cancelling out frequencies when the gases pass over the perforations;

a second end cover (10) having a hole mounted on the second end of the jacket (03) for serving as a support for the perforated outlet pipe (8) and for directing the exhaust gases out of the muffler (Y);

an exponential connector (11) fixed to the free end of the outlet perforated pipe (09); and

glasswool (12) spread across the whole of the region around the perforated outlet pipe (09) for absorbing the sound waves.

2. The muffler (Y) for automotive vehicles as claimed in claim 1, wherein the jacket (03) is divided into five chambers (A, B, C, D, E) with the help of the baffles (08, 05,07, 08), respectively.

3. The muffler (Y) for automotive vehicles as claimed in claim 1 or 2, wherein the inlet perforated pipe (01) is inserted from the first end cover (02) and extends up to the second chamber (B) through the hole of the perforated baffle (08).

4. The muffler (Y) for automotive vehicles as claimed in any one of claims 1 to 3, wherein the jacket (03) supports the baffles (8, 5, 7, 8) and prevents exhaust gases from leaking out.

5. The muffler (Y) for automotive vehicles as claimed in any one of claims 1 to 4, wherein the end plug (04) directs the gases to pass through the perforations in the inlet perforated pipe (01) and subsequently through the perforations in the baffle (08) resulting in noise attenuation.

6. The muffler (Y) for automotive vehicles as claimed in any one of claims 1 to 5, wherein the DOC unit (06) is fixed on the baffle (05) on the second chamber (B) and passes perforated baffle (07) on the third chamber (C) and end with fourth chamber (D).

7. The muffler (Y) for automotive vehicles as claimed in any one of claims 1 to 6, wherein the DOC unit (06) is placed equal distance on the second chamber (B) and third chamber (C).

8. The muffler (Y) for automotive vehicles as claimed in any one of claims 1 to 7, wherein the outlet perforated pipe (09) is inserted from the hole of the perforated baffle (08) on fourth chamber (D) and passes through the second end cover (10).

9. The muffler (Y) for automotive vehicles as claimed in any one of claims 1 to 8, wherein the distance from exponential connecter (11) on the perforated outlet pipe (09) which is fixed on fourth chamber (D) is 80mm.

10. An exhaust system having a muffler as claimed in any one of claims 1 to 9, comprising a inlet pipe assembly (W) connected at one end of the muffler (Y) so that exhaust gases from the internal combustion engine flows through the inlet pipe assembly (W) to the muffler (Y), and outlet pipe assembly (Z) connected at other end of the muffler (Y) so that the treated exhaust gases from the muffler (Y) flows to the atmosphere.