FORM 2
THE PATENT ACT 1970 (as amended)
[39 OF 1970]
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
[See Section 10 and Rule 13]
TITLE: A SINGLE PASS EXHAUST SYSTEM WITH PARALLEL ARRANGEMENT OF DISPERSIVE, REACTIVE AND ABSORPTIVE MEMBERS
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 nature of the invention and the manner in which it is to be performed.

FIELD OF INVENTION
The present invention generally relates to exhaust system and more particularly to a single pass exhaust system with parallel arrangement of dispersive, reactive and absorptive members for noise reduction and to minimize back-pressure.
BACKGROUND OF INVENTION
Various kinds of silencing devices are used with automotive vehicles in order to attenuate noise generated by exhaust gases which are emitted from internal combustion engines. Silencing devices are used to reduce or eliminated noise created when compressed gas is vented. The noise that is vented from a machine is harmful to human ear and can cause hearing loss over time, creating a health hazard for workers. Generally acoustic silencers or mufflers are designed to attenuate and/or absorb air-borne sound waves propagated in a flowing medium. The conventional noise reduction devices utilize dispersive, reactive and absorptive mufflers. The variety of conventional silencing devices include a quadruple pass with dispersive and reactive muffler, a double pass with dispersive and reactive muffler, single pass with dispersive muffler. Moreover in conventional silencing devices the muffler volume is reduced due to packaging constraints. These mufflers tackle various ranges /groups of frequencies and also contribute towards the back-pressure exerted upon the exhaust gases. Increased back pressure would result into adverse effect on engine endurance life, fuel efficiency reduction, and adverse effect on emission. Controlling backpressure and noise in an exhaust control systems are often a serious challenges to system designers. Hence there is a need for an arrangement to reduce the noise, and at the same time, minimize the back-pressure of exhaust system.
OBJECT OF THE INVENTION
One object of the present invention is to provide a single pass exhaust system with parallel arrangement of dispersive, reactive and absorptive members for noise reduction and to minimize back-pressure.
One object of the present invention is to provide a single pass exhaust system with parallel arrangement of dispersive, reactive and absorptive members to increase the muffler volume.

STATEMENT OF THE INVENTION
Accordingly the present disclosure provides a single pass exhaust system (10), comprising; a housing (12); a first cylindrical member (2) with an inlet for passing exhaust gas; a second cylindrical member (4) inline with said first cylindrical member (2) for exit of exhaust gases; a plurality of perforated baffle (6) provided for forming plurality of expansion chamber (3) in said in said housing, said first cylindrical member (2) and second cylindrical member (4) is separated by each other for expansion of part of gas in to an expansion chamber (3); a third cylindrical member (7) provided in parallel to said first cylindrical member (2) and second cylindrical member (4); and a plurality of sound absorbing member (8) sandwiched on inner surface of said shells/housing (12).
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
FIG. 1 shows a sectional view of a single pass exhaust system with parallel arrangement of dispersive, reactive and absorptive members according to embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to the drawings wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only, and not for the purpose of limiting the same.
One embodiment of the present disclosure provides a single pass exhaust system (10), comprising; a housing (12); a first cylindrical member (2) with an inlet for passing exhaust gas; a second cylindrical member (4) inline with said first cylindrical member (2) for exit of exhaust gases; a plurality of perforated baffle (6) provided for forming plurality of expansion chamber (3) in said in said housing, said first cylindrical member (2) and second cylindrical member (4) is separated by each other for expansion of part of gas in to an expansion chamber (3); a third cylindrical member (7) provided in parallel to said first cylindrical member (2) and second cylindrical member (4); and a plurality of sound absorbing member (8) sandwiched on inner surface of said shells/housing (12).
In one embodiment of the present disclosure, wherein said first cylindrical member (2) and second cylindrical member (4) having perforations (11) through which part of the exhaust gas passes in to said expansion chamber (3) to give lumped capacitance and transmission loss.

In one embodiment of the present disclosure, said expansion chamber (3) is a reactive member through which part of the gas is diverted towards second cylindrical member (4) and rest of the gas passes towards tail end of said expansion chamber (3).
In one embodiment of the present disclosure, said plurality of sound absorptive member includes an asbestos sheet (8) sandwiched between inner shells/housing (12) of the single pass exhaust system (10).
In one embodiment of the present disclosure, exhaust gas in said expansion chamber (3) passes through perforated baffle (6) and towards third cylindrical member (7) and finally come out of tail end of said second cylindrical member (4) to divert the exhaust gas out of said single pass exhaust system (10).
In one embodiment of the present disclosure, said cylindrical members, reactive member and absorptive members are arranged in parallel to minimize the back-pressure.
In one embodiment of the present disclosure, said plurality of baffles (6) are made of acoustic material that are attached to the interior of said single pass exhaust system (10) housing forming path for the pressurized gas flow.
According to present invention said first second and third cylindrical member’s perforations. As the gas passes through the cylindrical members, part of the gas disperses through perforations and gets mixed well in the expansion member to give lumped capacitance and transmission loss. The expansion chamber acts as a reactive member, through which part of the gas is diverted towards second cylindrical member and rest of the gas passes towards tail end of said expansion chamber. According to present invention, the incident and reflected sound waves in said expansion chamber interfere with each-other out of phase to ensure transmission loss. The plurality of asbestos sheets sandwiched on inner surface of said housing acts as an absorptive member to absorb the sound. The exhaust gas in said expansion chamber passes through perforated baffle and towards third cylindrical member and finally comes out of tail end of said second dispersive muffler to divert the exhaust gas out of said housing.

According to present invention, the dispersive member, reactive member and absorptive members are arranged in parallel to minimize the back-pressure. The pluralities of baffles are made of acoustic material that is attached to the interior of said silencer housing forming path for the pressurized gas flow.
The single pass exhaust system (10) with parallel arrangement of dispersive, reactive and absorptive mufflers according to embodiment of the present invention is as shown in FIG. 1. The single pass exhaust system is provided to minimize the back pressure, to reduce the noise and to increase muffler volume. The exhaust system (10) comprising a housing/shell (12), a first cylindrical member (2) with an inlet (1) for passing exhaust gas, a second cylindrical member (4) with an outlet (5) for exit of exhaust gases. A plurality of perforated baffle (6) is provided for forming plurality of expansion chamber in said housing (12). The first cylindrical member (2) and second cylindrical member (4) are separated by each other for expansion of gas in to an expansion chamber (3) in said housing (12). The expansion chamber (3) acts as a reactive member. A third cylindrical member (7) provided in parallel to said first cylindrical member (2) and second cylindrical member (4), and a plurality of asbestos sheet (8) sandwiched on inner surface of said housing (12). According to present invention, the dispersive member, reactive member and absorptive members are arranged in parallel to minimize the back-pressure. The first cylindrical member (2) is inline with second cylindrical member (4). The pluralities of baffles (6) are made of acoustic material that is attached to the interior of said exhaust system (10) forming path for the pressurized gas flow.
According to present invention, as the gas passes through the first cylindrical member (2) part of the gas disperses through perforations (11) and gets mixed well in the expansion chamber (3). The expansion chamber (3) acts as a reactive member, through which part of the gas is diverted towards second cylindrical member (4) and rest of the gas passes towards tail end (5) of said expansion chamber (3). A part of the exhaust gas in the second cylindrical member (4) also escapes in to the expansion chamber (4). The gas which is escaped in the expansion chamber (3) enters into the third cylindrical member (7) through perforation provided in said baffles (6) and perforated portion of said third cylindrical member (7). The third cylindrical member (7) is having a non-perforated portion (9) which is arranged in said expansion chamber (3). The third cylindrical member (7) is provided parallel to said first cylindrical member (2) and second

cylindrical member (4). The incident and reflective sound waves in said expansion chamber interfere with each-other out of phase to give lumped capacitance and transmission loss. In this manner, the volume of single pass exhaust system (10) is also increased to expand the gas. The plurality of asbestos sheets sandwiched between the shells of the exhaust system acts as an absorptive member to absorb the sound. For example a ceramic sheet is sandwiched between shells for absorbing high frequency noise. The exhaust gas in said expansion chamber passes through perforated baffle and towards third cylindrical member (7) and finally comes out of tail end (5) of said second cylindrical member (4) to divert the exhaust gas out of said single pass exhaust system (10). The use of combination dispersive member, reactive member and absorptive members gives better noise reduction with respect to conventional single type of exhaust system. According to present invention, the reactive member is affective in sinusoidal nature across frequency range, the dispersive member is effective over wide range but has limited magnitude of noise attenuation and the absorptive member is effective for only high frequencies.
Advantages:
The present invention provides a single pass exhaust system with parallel arrangement of
dispersive, reactive and absorptive members for noise reduction and to minimize back-pressure.
The single pass exhaust system according to present invention is provided to increase the muffler volume.
The foregoing description is a specific embodiment of the present invention. It should be appreciated that this embodiment is described for purpose of illustration only, and that numerous 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.

Referral Numerals:

Reference number Description
1 Inlet
2 First cylindrical member
3 Expansion chamber
4 Second cylindrical member
5 Outlet
6 Perforated baffles
7 Third cylindrical member
8 Asbestos sheet
9 Non- perforated portion
of third cylindrical
member
10 Exhaust system
11 Perforations
12 Housing/shell

We Claim:
1. A single pass exhaust system (10), comprising;
a housing (12);
a first cylindrical member (2) with an inlet for passing exhaust gas; a second cylindrical member (4) inline with said first cylindrical member (2) for exit of exhaust gases; a plurality of perforated baffle (6) provided for forming plurality of expansion chamber
(3) in said in said housing, said first cylindrical member (2) and second cylindrical member
(4) is separated by each other for expansion of part of gas in to an expansion chamber (3);
a third cylindrical member (7) provided in parallel to said first cylindrical member (2) and second cylindrical member (4); and
a plurality of sound absorbing member (8) sandwiched on inner surface of said shells/housing (12).
2. The single pass exhaust system as claimed in claim 1, wherein said first cylindrical member (2) and second cylindrical member (4) having perforations (11) through which part of the exhaust gas passes in to said expansion chamber (3) to give lumped capacitance and transmission loss.
3. The single pass exhaust system as claimed in claim 1, wherein said expansion chamber
(3) is a reactive member through which part of the gas is diverted towards second
cylindrical member (4) and rest of the gas passes towards tail end of said expansion
chamber (3).
4. The single pass exhaust system as claimed in claim 1, wherein said plurality of sound absorptive member includes an asbestos sheet (8) sandwiched between inner shells/housing (12) of the single pass exhaust system (10).
5. The single pass exhaust system as claimed in claim 1, wherein exhaust gas in said expansion chamber (3) passes through perforated baffle (6) and towards third cylindrical member (7) and finally come out of tail end of said second cylindrical member
(4) to divert the exhaust gas out of said single pass exhaust system (10).

6. The single pass exhaust system as claimed in claim 1, wherein said cylindrical members, reactive member and absorptive members are arranged in parallel to minimize the backpressure.
7. The single pass exhaust system as claimed in claim 1, wherein said plurality of baffles (6) are made of acoustic material that are attached to the interior of said single pass exhaust system (10) housing forming path for the pressurized gas flow.
8. The single pass exhaust system as herein described with reference to accompanying drawings.