CIRCULAR HYBRID MUFFLER

FIELD IF INVENTION

The invention relate to the design of muffler, which are used to control noise in the exhaust system. The invention particularly relates to the designs of circular muffler, which has increased.

BACKGROUND OF THE INVENTION
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.

The drawback of conventional muffler is that it consumes larger packaging space leading to a shorter tail pipe & sharp bends of the tail pipes in some vehicles. As the muffler has a higher length, it is very difficult to package the muffler in the already limited space available. Also, the existing conventional muffler requires more number of brackets as it is longer in length and requires additional length tail pipes to bring the tailpipe outlet to the side of the vehicle. Another problem with the conventional muffler is, because of the elongated tail pipe, there is an increased back pressure which hampers the proper running of the engine. This also means that there is lesser scope for noise attenuation as the muffler back pressure is forced to be lower.

In addition to these, there is a need for exhaust systems to meet stricter emission norms. In such cases, 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 re-circulation). 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.
In case of petroleum tanker application, conventionally a front exhaust system was made use. A muffler with outlet on the side of the vehicle is very dangerous as the hot exhaust gases flow close to the tanker body. This could lead to severe consequences. This is the reason for the incorporation of a front-exhaust system. It comprised of an additional spark arrestor, which helps filter the larger particles of unborn fuel which would otherwise come out of the tail pipe. This was a precaution to prevent the production of any spark.

For vehicles which comply with higher emission norms, there is a need for after treatment devices. But for a front exhaust system where packaging is already a constraint, further addition of components is not manageable. Also, the new safety standards for smaller vehicles on road calls for additional under-protection devices, like FUPD (front under protection device), RUPD (rear under protection device) and SUPD (side under protection device). This calls for additional space requirements.

OBJECT OF THE INVENTION
The object of the present invention is to design the muffler in such a way so that it piping of required for the exhaust system as low as possible, which results in reduced back pressure, which improves the engine performance.

It is also an object of the invention, to provide a single new muffler that would reduce overall noise by providing 180 degree flow reversal.

Yet another object of the present invention is to complex 3-diamention flow and better circulation/configuration action thereby minimizing the sound level.

SUMMERY OF THE INVENTION

In order to achieve the above objective, the present invention provides a novel advanced integrated muffler for an inline pump engine, which incorporates the noise reduction principle of reflection and absorption and there by reduces the exhaust noise.

Accordingly, the present invention provides a hybrid muffler mounted vertically for automotive vehicles comprising a hollow jacket having a first and second end cover; a first end cover with a hole on the first end of the jacket; a second end cover with a hole on the second end of the jacket; three perforated baffles with four, seven and one holes respectively in such a manner that the jacket is divided into 2 chambers by the two baffles, an inlet pipe extending from the first end of the jacket up to the third chamber of the jacket through the holes in the first end cover and the first and second perforated baffles. One end of the inlet pipe is connected to a flange on one end and a connector is mounted on the other end; An outlet pipe extending from second end of the jacket up to the first chamber of the jacket through the holes in the said end cover and the baffles and the fourth chamber is wrapped with glass wool material. The inlet pipe consist of 3 set of perforation zones and outlet pipe consist of 5 perforation zones with varying diameter and spacing to attenuate different frequencies which are being generated by engine/cylinder firing. The first chamber (A) consist of two perforation zones of inlet pipe and second chamber (B) consist of one perforation zone of inlet pipe. First chamber (A) consist of two perforation zones of outlet pipe and second chamber (B) consist of three perforation zones of outlet pipe.

The packaging is done in such a way that the piping required for the exhaust system is as low as possible. This results in lower back pressure which improves the engine performance. The design of the hybrid muffler is done in such a manner, that the sound level of the exhaust gases coming out of the muffler is very low. This is achieved by means of various features incorporated in this system. Muffler design is such that two 180-degree flow reversal elements have been incorporated. Providing such flow reversal elements forces the gases to flow in a longer path thereby reducing overall noise.

Further, in order to achieve good noise reduction, several perforation zones have been provided in the inlet and outlet pipes, which help in more complex 3-dimensional flow and better circulation centrifugal action thereby minimizing the sound level. A total of 8 perforation zones have been used at different locations. In addition to this, special purpose absorptive material has been added at critical positions in the flow path which will inhibit the passage of the sound waves through the flow chambers. Special acoustic elements like exponential connector and plug connectors have been added which help in increasing the flow path through flow reversal, thereby providing noise benefits.

Two different types of materials used in the present invention, Aluminised steel used for the parts which are having direct contact with atmosphere, Aluminised steel parts gives additional structural durability / salt spray life. In addition to this Heat resistance Aluminium paint applied over the muffler externals to have better structural durability / salt spray life. All the internal parts are made of ERW sheets as it does not have any direct contact with atmosphere to have better cost advantage. Usage of two different materials gives the benefit of better life with minimal increase in cost.

The present invention provides consistent performance with reduced weight and reduced cost. Moreover, it has the advantages of decreased variety, simple vehicle assembly and reduced component assembly time.

BRIEF DESCRIPTION OF DRAWING

Figure 1 illustrates the perspective view of present application.

Figure 2 shows the front view of circular hybrid muffler according to the present invention.

Figure 3 illustrates the cross sectional view of the circular hybrid muffler according to the present invention.

Figure 4a and 4b Cross sectional and top view of the Jacket.

Figure 5a and 5b shows the sectional view of the inlet pipe and outlet pipe.

Figure 6a shows the cross sectional view of the flared tube

Figure 6b shows the cross sectional view of the connector.

Figure 7 illustrates the combination of all flow paths of the exhaust gas through the muffler.

DETAILED DESCRIPTION OF THE INVENTION

Referring to figure 1, the perspective view of the present invention, illustrate the configuration of circular hybrid muffler with the exhaust line.

Referring to figure 2, the cross sectional front view of the present invention illustrate a hollow jacket (05) which is covered at both ends by end covers (04 & 08) having a hole. The jacket (05) is divided into three chambers (A, B & C) with a help of two perforated baffles (06, 07) has four and one holes respectively. An inlet pipe (02) is inserted from the first end cover (04) and extends up to second chamber of the jacket through the holes in the end cover (04) and the perforated baffle (06). One end of the inlet pipe (02) is connected to a flared tube (01)from the engine side and the other end of the inlet pipe (02) is fitted with a connector (03).

An outlet pipe (09) is inserted from the second end cover (08) and extends up to the first chamber of the jacket (05) through the hole in the second end cover (08) and the baffles (06 & 07). The third chamber (C) is filled with glass wool material with thickness of filament in microns called silentex.

A portion of the inlet pipe (02) which is placed in the first and the second chamber (A and B) comprises of three perforation zones of predetermined size to eliminate certain frequencies. The outlet pipe (09) comprises three perforation zones to kill certain frequencies. Each row of perforation is staggered compared to adjacent row of perforations for a given set.

The third chamber (C) is filled with glass wool having filament thickness in microns; there is more surface contact between the exhaust gas escaped from the perforations & the filaments of glass wool. This results in friction & conversion of acoustic energy in to heat energy, thus helping further transmission loss.
Referring to figure 3, the cross sectional view of the cylindrical hybrid muffler according to the present invention depicts the diameter and arrangement for the inlet pipe and out let pipe accommodated inside the hollow jacket.

Referring to figure 4a and 4b illustrate the hollow jacket (05).

Referring to figure 5a, the inlet pipe the different perforation zones are arranged. Each row of perforation is staggered compared to adjacent row of perforation. In a preferred embodiment, the diameter of the perforation can be from 5.5mm to 6.5mm and the pitch i.e. distance between corresponding points of consecutive rows can be about 18mm. The inlet pipe could have about 12 rows of perforation with 16 perforations per row. The inlet pipe could extend into the second chamber (B) for 70 mm to 90mm, preferably 80mm. The connector (03) which is fixed to the free end of the inlet pipe (02) converges from about 73mm outer diameter at the end to abut 50mm inner diameter at the other end with a width of about 10mm.

Referring to figure 4b, the cross sectional view of the outlet pipe, illustrate the arrangement of perforations. The first perforation zone is made in the outlet pipe (09) which is paced in the third chamber (C). Preferably, the diameter of the first perforation zone can be from 3.5mm to 4.5mm and the pitch cab be about 12mm. The first set could contain about 17 rows of perforations with about 20 perforations per row. The second perforation zone is made in the outlet pipe (09) which runs through the third chamber (C). Preferably, the diameter of the second perforation zone can be from 2.0mm to 2.8mm and the pitch can be about 8mm. The second set could contain about 9 rows of perforations with about 20 perforations per row. The third perforation zone is provided in the outlet pipe (10) which runs through second chamber (B). Preferably, the diameter of the third perforation zone is from 2.4mm to 3.2mm and the pitch can be about 19mm. The third set could contain about 19 rows of perforations with about 13 perforations per row. The outlet pipe (10) runs through all four chambers and extends in the first chamber (A) for 70mm to 90mm, preferably 70mm.

Referring to figure 6a the cross sectional view of the flared plates shows the preferred measurements of the flared tube.

Referring to figure 6b, illustrate the connector, having a taped edge at the free end and capable of being connected to the posterior end of the inlet pipe for increased transmission loss.

Referring to figure 7 illustrates the combination of all flow paths of the exhaust gas through the muffler. Each flow path is selected by the exhaust according to the nature of the particulate matter and noise content in gas. Each set of perforation is designed in order to provide maximum transmission loss to the exhaust gas. According to the embodiment of the present invention, four flow paths are available for the exhaust gas as illustrated. As the exhaust gas enter through the inlet pipe, the filtration process takes place through the different set of perforations according to the particulate matter and noise present in the exhaust gas.

The inlet and outlet pipes are arrange parallel to each other as well as to maintain specific flow paths as described herein.

The flow path represented by "W" starts from the inlet pipe and pass through entire length of inlet pipe and outlet pipe. Further, the flow path represented by "X" is, wherein the amount of gas getting filtered through first set of perforations from the inlet pipe and pass through the entire length of outlet pipe. The third flow path is represented by "Y" wherein the said flow path the exhaust gas filtered through the third set of perforation of the inlet pipe is entering in the outlet pipe through the first set of perforations and expelled though the outlet pipe. The last flow path 7" starts form the inlet pipe. This flow path constitutes the entire length of the inlet pipe and second set of perforations of the outlet pipe till end portion.
The working of the muffler of the present invention is explained in detail herein below: The muffler according to the present invention uses both the principles of reflective and absorptive principles.

REFLECTIVE PRINCIPLE:
The first 2 chambers (A, B, C) of the hollow jacket (05) form the reflective muffler. As the exhaust gas enters the inlet pipe, it goes straight to second chamber because there is no other path to escape in to first chamber. On entering the second chamber (B) it comes across the 1st set of perforation of the Inlet pipe & some gas (g) thus escapes from the inlet pipe in to the shell around the inlet pipe, this phenomenon cab be explained by following two points

1. Expansion: The exhaust gas is initially present in the pipe, which is of smaller diameter compared to the hollow 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.

2. Pipe perforation: The perforations are the specific designs to kill certain frequencies during the passage of the gas from inside of the pipe to outside of the pipe. The thickness of the pipe also plays a role. This gives the benefit of transmission loss.

Some of the exhaust gas of the inlet pipe goes straight & hits the connectors at the end and gets reflected resulting in reflected waves that cancel some of the incoming waves. This gives the benefit of transmission loss. Some of the gas passes through the centre of the pipe & bangs with the baffle (06) that is positioned in front of the inlet pipe. This results in reflected waves that cancel some of the incoming waves, Here the expansion principle as explained above also holds true, the only difference is that some gas expands directly though the connector in to the shell.

Some of the exhaust gas (gl+g23+g22) of the inlet pipe tries to enter the perforation of the outlet pipe in 2nd chamber (B) & 3rd chamber (C). This results in interaction of the gases that are trying to come out of the outlet pipe & the gases that are trying to enter the outlet pipe through the perforation, giving rise to molecular interaction & the acoustic energy loss. The gas that has occupied the shell (gs=gl+g23+g22) passes through the connectors of the baffles (06,07) & tries to enter the outlet pipe in the first chamber, This gas further comes across the perforation in the 2nd chamber resulting in an phenomenon as explained for inlet pipe above. The same phenomenon gets further repeated when it comes across the perforation of the outlet pipe in 3rd chamber. It is to be noted that the exhaust gas that is entering the muffler has high pressure & there is heavy interaction of the gas molecules by virtue of reflection caused by various elements including the impingement of the gases on the inner surface of the jacket. This also adds to the transmission loss.

ABSORPTIVE PRINCIPLE:

The exhaust gas that passes away through the outlet pipe of 2rd chamber (B) gets further carried away to 3rd chamber (C). This gas comes across the outlet pipe perforation in the 3rd chamber. Part of this gas escapes in to the shell through the perforations by blasting the glass wool bag that is wrapped around the perforation, resulting in attenuation of certain frequencies & spread of the glass wool across the whole chamber. The remaining exhaust gases escape the muffler.

As the third chamber (C) is filled with glass wool having filament thickness in microns, there is more surface contact between the exhaust gas escaped from the perforations & the filaments of glass wool. This results in friction & conversion of acoustic energy in to heat energy, thus helping further transmission loss. Thus the noise level of the exhaust gas of the vehicle is reduced to the required level before leaving the chamber.

It should be noted that the muffler of the present invention can also be used to reduce the noise level of the exhaust gas of power generator and the like.

The above explanation merely illustrates the principle of the invention. It will thus be appreciated that those skilled in the art will be able to devise various arrangements which, although not explicitly described or shown herein embody the principles of the invention and are included within the spirit and scope.

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.

We Claim,

1. A circular hybrid muffler comprising

a hollow jacket (5) having a first end cover (4) and a second end cover (5); an inlet pipe (2) and an outlet pipe (9) having provision to accommodate set of plurality of perforated zones;

plurality of baffles (6 and 7) constituting holes to support the inlet pipe (2) and outlet pipe(9);

wherein the baffle plates are arranged to form plurality of chambers inside the hollow jacket (5) at optimum locations to generate opposite waves to neutralize the waves generated by engine; and
the inlet pipe (2) and outlet pipe (9) are arranged parallel to each other inside the hollow jacket (5).

2. The circular muffler as claimed in claim 1 comprises a flared tube (1) that facilitate the air intake of the muffler and the said flared tube connects inlet pipe (2) with the engine exhaust.

3. The circular muffler as claimed in claim 1 comprises a connector (03) having a taped edge at the free end and capable of being connected to the posterior end of the inlet pipe (2) for increased transmission loss.

4. The circular muffler as claimed in claim 1 wherein the baffle plates (6 and 7) , optimally arranged interior to the hollow jacket (5) forming three chambers (A,B,C); and

holes are provided on the said baffles (6 and 7) in order to configure inlet and outlet pipes (9).

5. The circular muffler as claimed in claim 1 and 4, wherein the inlet pipe (2) consist of 3 set of perforations and outlet pipe consist of 5 set of perforations with varying diameter and spacing to attenuate different frequencies which are being generated by engine/cylinder firing.

6. The circular muffler as claimed in claim 1, 4 and 5, wherein the first chamber (A) comprising two sets of perforations of inlet pipe (2) and second chamber (B) comprising one set of perforations of inlet pipe.

7. The circular muffler as claimed in claim 1 and 4 to 6, wherein the first chamber (A) comprising two sets of perforations of outlet pipe (9) and second chamber (B) comprising three sets of perforations of outlet pipe.

8. The circular muffler as claimed in 1 and 4, wherein the third chamber ( C) is packed with glass wool (10) having filament thickness in microns.

9. The circular muffler as claimed in any of the previous claims, wherein the exhaust gas flow path Is determined by the noise content of the exhaust gas; and

the baffle plates, inlet pipe (2) and outlet pipe (9) are configure to introduce a maximum flow path along with creating a counter flow of escaped gas from inlet pipe (2) to eliminate all achievable noise frequencies.