[001] The subject matter in general relates to structure of a muffler shell in
exhaust gas system of a vehicle. More particularly, but not exclusively, the subject
matter relates to reducing exhaust noise caused due to exhaust gas in the muffler
5 shell.
BACKGROUND
[002] Background description includes information that may be useful in
understanding the present subject matter.
[003] One of the priorities in any mode of transportation is the comfort on
10 offer for the occupants including the drivers and the passengers and is generally
termed as cabin comfort. This greatly determines the drive quality of the vehicle.
Cabin comfort in passenger cars may refer to the vehicle’s effectiveness in
insulating the occupants from undulations in the road surface, for example, bumps
and the outside noise and vibration.
15 [004] Cabin noise is one of the major governing parameter of comfort in
passenger cars. Cabin noise can add to the driver’s fatigue during long journeys,
which can impact the driver's ability to control the vehicle and may have
detrimental effects. One of the causes for cabin noise is the noise generated by the
exhaust system of the vehicle. The vehicle exhaust system consists of long pipes
20 and gas expansion chambers called mufflers to attenuate back pressure and noise.
The muffler is designed so as to misdirect exhaust gases of the internal
combustion engine back toward the engine or around an internal chamber and
creates a destructive interference for controlled noise cancellation.
[005] The exhaust noise consists of majorly three components, pulsation
25 noise, shell noise, and flow generated noise. The pulsation noise is caused due to
pressure pulses generated by opening and closing of exhaust port and gas column
resonance. The noise gets amplified if pulsation frequency resonates with gas
3
column frequency and exhaust system vibration frequency. The shell noise is
generated mainly due to pulsating exhaust gas flow hitting muffler outer surface
(also called muffler shell) and causing shell structural vibrations. The flow
generated noise is generated due to turbulence and vortex shedding of gas flow
5 and is normally very broad band noise but it can also have a tonal region which
sounds like a whistle.
[006] Referring to FIG. 1, disclosed is a conventional exhaust muffler 100.
The exhaust muffler 100 includes an exhaust pipe 102, a muffler shell 104, and
end plates 106, wherein the muffler shell 104 encloses the outer surface of the
10 exhaust pipe 102. The muffler shell 104 has a uniform thickness throughout and is
cylindrical in shape. The exhaust pipe 102 has pores 110 on its surface for the
exhaust gases to escape through it during high pressure (as shown in fig. 2). The
end plates 106 are provided at both ends of the muffler shell 104 and encloses the
outer surface of the exhaust pipe 102.
15 [007] Another embodiment of the exhaust muffler, there is no exhaust pipe
inside the muffler shell. The exhaust pipe is connected with the end plates.
[008] Referring to FIG. 2, when the exhaust gases pass through the
conventional exhaust muffler 100, the exhaust gases escape through the pores 110
and comes in contact with inner surface of the muffler shell 104.
20 [009] FIG. 3 discloses the excitation of the muffler shell due to the exhaust
gases passing through the exhaust pipe 102. The excitation observed is too high
and creates noise that travels to the cabin of the vehicle causing discomfort to the
occupants.
[0010] There are techniques employed to control exhaust noise occurring due
25 to structural vibration such as, increasing muffler shell thickness, adding support
baffle, optimizing weld location on muffler shell, providing double layered
muffler shell with insulation, adding glass wool in resonating chambers which
avoids the exhaust gases coming in contact with the muffler shell, and changing
4
exhaust shell design.
[0011] Another technique used to control the exhaust noises is by changing
the muffler shell 200 design as shown in FIG. 4. The muffler shell 200 defines
embosses or bead patterns on the surface to reduce shell vibrations. However,
5 such solution does not cater to entire frequency band noise. Such designs only
help in improving high frequency vibration of the exhaust muffler.
[0012] Referring to FIG. 5, Chinese patent CN102644531B discloses a
resonator system 300 that is used in a gas inlet system. The resonator 300
comprises a housing 302, within which a second air pipe 312 is enclosed for the
10 gas to flow through. The housing 300 defines multiple chambers, such as first
chamber 306, second chamber 308 and third chamber 310. The chambers 306,
308, 310 are arranged such that the radial cross section of the chambers 306, 308,
310 decrease from one end to the other. The first chamber 306 has the largest
radial cross section and the third chamber 310 has the smallest radial cross
15 section.
[0013] Each chamber 306, 308, 310 of the resonator 300 is divided into
multiple resonant cavities (not shown) and each resonant cavity is configured to
offset a particular range of frequencies, thereby reducing the noise in the intake
system of the vehicle.
20 [0014] Similarly, two other Chinese patents CN107514325A and
CN209724546(U) disclose muffler that define multiple chambers as in the
Chinese patent CN102644531B. These chambers are configured to cancel out a
set of frequencies to reduce the noise.
[0015] However, the above designs are meant to reduce noise of specific
25 frequency (small frequency band) using the concept of resonator. These designs
use several chambers and multiple resonant cavities, wherein each resonant
cavity/chamber is designed to cancel out a specific range of frequency noise.
Further, the existing solutions are complex and costly as well.
5
[0016] Therefore, there is a need for an improved and cost effective exhaust
muffler that can solve broad band frequency noise problem generated due to
muffler shell vibration.
OBJECTS OF THE DISCLOSURE
5 [0017] In view of the foregoing limitations inherent in the state of the art,
some of the objects of the present disclosure, which at least one embodiment
herein satisfy, are listed herein below.
[0018] It is an object of the present disclosure to propose an exhaust muffler
for reducing exhaust noise.
10 [0019] It is another object of the present disclosure to propose a muffler shell
that reduces the vibration in the exhaust muffler.
[0020] It is yet another object of the present disclosure to propose a muffler
shell with increased local stiffness.
[0021] It is still yet another object of the present disclosure to propose a
15 muffler shell that reduces both low and high frequency vibrations.
[0022] These and other objects and advantages of the present invention will
be apparent to those skilled in the art after a consideration of the following
detailed description taken in conjunction with the accompanying drawings in
which a preferred form of the present invention is illustrated.
20 SUMMARY
[0023] This summary is provided to introduce concepts related to reducing
exhaust noise. The concepts are further described below in the detailed
description. This summary is not intended to identify key features or essential
features of the claimed subject matter, nor is it intended to be used to limit the
25 scope of the claimed subject matter.
6
[0024] The present disclosure relates to a structure of an exhaust muffler for
reducing exhaust noise. The exhaust muffler includes a muffler shell comprising a
front conical frustum shape member having an end portion and a base portion; and
a rear conical frustum shape member having an end portion and a base portion,
5 wherein the base portion of the front conical frustum shape member joined with
the base portion of the rear conical frustum shape member to define structure of
the muffler shell.
[0025] In an aspect, the front conical frustum shape member is identical with
the rear conical frustum shape member.
10 [0026] In an aspect, diameter of the front conical frustum shape member
increases from the end portion towards the base portion.
[0027] In an aspect, diameter of the rear conical frustum shape member
increases from the end portion towards the base portion.
[0028] In an aspect, the end portion of the front conical frustum shape
15 member and the end portion of the rear conical frustum shape member defines a
diameter ‘d’ smaller than diameter ‘D’ of the base portion of the front conical
frustum shape member and the base portion of the rear conical frustum shape
member.
[0029] In an aspect, outer surface of the muffler shell defines steps to
20 increase local stiffness of the muffler shell.
[0030] In an aspect, a circular plate having a hole to receive the exhaust pipe
provided at the end portions of the muffler shell.
[0031] In an aspect, the circular plate is welded with the end portions of the
muffler shell.
25 [0032] In an aspect, the front conical frustum shape member and the rear
conical frustum shape member are joined by means of welding.
7
[0033] Other objects, features and advantages of the present disclosure will
become apparent from the following detailed description. It should be understood,
however, that the detailed description and the specific examples, while indicating
specific embodiments of the invention, are given by way of illustration only, since
5 various changes and modifications within the spirit and scope of the invention will
become apparent to those skilled in the art from this detailed description.
BRIEF DESCRIPTION OF DRAWINGS
[0034] While the specification concludes with claims particularly pointing
out and distinctly claiming the subject matter that is regarded as forming the
10 present subject matter, it is believed that the present disclosure will be better
understood from the following description taken in conjunction with the
accompanying drawings, where like reference numerals designate like structural
and other elements, in which:
[0035] FIG. 1 is an isometric view of a conventional exhaust muffler;
15 [0036] FIG. 2 is an orthogonal projection of exhaust gases passing through
the exhaust pipe of the conventional exhaust muffler as shown in FIG. 1;
[0037] FIG. 3 is a vibration analysis made on conventional exhaust muffler;
[0038] FIG. 4 is an isometric view of another conventional exhaust muffler;
[0039] FIG. 5 is an isometric view of a prior art;
20 [0040] FIG. 6 is an isometric view of an exhaust muffler, in accordance with
an embodiment of the prevent invention;
[0041] FIG. 7 is a side view of a part of a muffler shell of the exhaust
muffler, in accordance with an embodiment of the prevent invention;
[0042] FIG. 8 is a graph representing the vibration of the conventional
25 exhaust muffler as shown in FIG. 1 for frequencies ranging from 0-1000Hz;
8
[0043] FIG. 9 is a graph representing the vibration of the exhaust muffler as
shown in FIG. 6 for frequencies ranging from 0-1000Hz, in accordance with an
embodiment of the present invention;
[0044] FIG. 10 is a graph representing the vibration of the conventional
5 exhaust muffler as shown in FIG. 1 for frequencies ranging from 1000-6000Hz;
[0045] FIG. 11 is a graph representing the vibration of the exhaust muffler as
shown in FIG. 6 for frequencies ranging from 1000-6000Hz, in accordance with
an embodiment.
DETAILED DESCRIPTION
10 [0046] The detailed description of various exemplary embodiments of the
disclosure is described herein with reference to the accompanying drawings. It
should be noted that the embodiments are described herein in such details as to
clearly communicate the disclosure. However, the amount of details provided
herein is not intended to limit the anticipated variations of embodiments; on the
15 contrary, the intention is to cover all modifications, equivalents, and alternatives
falling within the spirit and scope of the present disclosure as defined by the
appended claims.
[0047] It is also to be understood that various arrangements may be devised
that, although not explicitly described or shown herein, embody the principles of
20 the present disclosure. Moreover, all statements herein reciting principles, aspects,
and embodiments of the present disclosure, as well as specific examples, are
intended to encompass equivalents thereof.
[0048] The terminology used herein is for the purpose of describing particular
embodiments only and is not intended to be limiting of example embodiments. As
25 used herein, the singular forms “a”, “an”, and “the” are intended to include the
plural forms as well, unless the context clearly indicates otherwise. It will be
further understood that the terms “comprises”, “comprising”, “includes”,
9
“consisting” and/or “including” when used herein, specify the presence of stated
features, integers, steps, operations, elements and/or components, but do not
preclude the presence or addition of one or more other features, integers, steps,
operations, elements, components and/or groups thereof.
5 [0049] It should also be noted that in some alternative implementations, the
functions/acts noted may occur out of the order noted in the figures. For example,
two figures shown in succession may, in fact, be executed concurrently or may
sometimes be executed in the reverse order, depending upon the functionality/acts
involved.
10 [0050] Unless otherwise defined, all terms (including technical and scientific
terms) used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which example embodiments belong. It will be further
understood that terms, e.g., those defined in commonly used dictionaries, should
be interpreted as having a meaning that is consistent with their meaning in the
15 context of the relevant art and will not be interpreted in an idealized or overly
formal sense unless expressly so defined herein.
[0051] Referring to FIG. 6, disclosed is a structure of an exhaust muffler 500
for reducing exhaust noise. The exhaust muffler 500 includes a muffler shell 400
configured to cover the exhaust pipe 416. The muffler shell 400 comprises a front
20 conical frustum shape member 402 and a rear conical frustum shape member 408.
The front conical frustum shape member 402 defines an end portion 404 and a
base portion 406. Similarly, the rear conical frustum shape member 408 defines an
end portion 410 and a base portion 412. The front conical frustum shape member
402 is identical in shape and configuration with the rear conical frustum shape
25 member 408. The base portion 406 of the front conical frustum shape member 402
is joined with the base portion 412 of the rear conical frustum shape member 408
to define structure of the muffler shell 400. The joining line of the base portions
406, 412 defines mid-portion of the muffler shell 400. Diameter of the front
conical frustum shape member 402 increases from the end portion 404 towards
10
the base portion 406. Similarly, diameter of the rear conical frustum shape
member 408 increases from the end portion 410 towards the base portion 412.
[0052] In an embodiment, diameter of the muffler shell 400 increases from its
end portions 404, 410 towards mid portion (base portions 406, 412) of the muffler
5 shell 400. This defines a curvature in outer surface of the muffler shell 400. The
curvature reduces low frequency vibrations in the muffler shell 400. With reduced
low frequency vibrations, the noise due to muffler shell resonance is also reduced.
[0053] In an embodiment, the outer surface of the muffler shell 400 defines
steps 414 (as shown in FIG. 7). In the front conical frustum shape member 402,
10 the steps 414 ascend from the end portion 404 towards the base portion 408 (i.e.,
mid portion of the muffler shell 400). Similarly, in the rear conical frustum shape
member 402, the steps 414 ascend from the end portion 410 towards the base
portion 412 (i.e., mid portion of the muffler shell 400). The presence of these
steps 414 increase local stiffness of the muffler shell 400. The steps 414 also
15 reduces mid and high frequency vibrations in the muffler shell 400. With reduced
mid and high frequency vibrations, the noise due to muffler shell 400 is also
reduced.
[0054] At the end portions 404, 410 of the front conical frustum member 402
and the rear conical frustum member 408 respectively, a circular plate 404a, 410a
20 having a hole to receive the exhaust pipe 402 is welded to form an enclosure. The
circular plates 404a, 404b are made of sheet material and welded on the end
portions 404, 410 to form an enclosure.
[0055] In an embodiment, the overall volume of the muffler shell 400 is kept
same as that of a muffler shell 102 with a circular outer surface 108 (as shown in
25 FIG. 1).
[0056] In an embodiment, diameter of the end portion 404 of the muffler
shell 400 is smaller than an end portion 106 of the muffler shell 102 with the
circular outer surface 108 (shown in FIG. 1).
11
[0057] In an embodiment, the muffler shell 400 comprises two parts 400a
and 400bwhere both parts are identical to each other as shown in fig. 6.
[0058] Referring to FIG. 7, the end portion 404, 410 define a diameter ‘d’
and the base portion 406, 412 defines a diameter ‘D’. Diameter ‘D’ of the base
5 portion 406, 412 is greater than the diameter ‘d’ of the end portion 404, 410 of the
muffler shell 400.
[0059] In an embodiment, sides of a sheet material are welded to form the
front conical frustum member 402. Similarly, sides of a sheet material are welded
to form the rear conical frustum member 408. Base portions 406, 412 of the two
10 conical frustum shaped members are welded with each other to form the muffler
shell 400.
[0060] In an embodiment, the material of the sheet material is steel.
[0061] Referring to FIGs. 8 and 9, a conventional exhaust muffler 100 with
the muffler shell 104 that has the circular outer surface and the exhaust muffler
15 500 with the muffler shell 400 having the stepped configuration as explained in
FIGs. 6-7, are subjected to frequencies varying from 0-1000Hz. The vibrations
are very less in the exhaust muffler with the muffler shell 400 when compared to
the vibrations in the conventional exhaust muffler 100 with the muffler shell 104.
[0062] Referring to FIGs. 10 and 11, the conventional exhaust muffler 100
20 with the muffler shell 104 that has the circular outer surface and the exhaust
muffler 500 with the muffler shell 400 that has the stepped configuration as
explained in FIGs. 6-7, are subjected to frequencies varying from 1000-6000Hz.
The vibrations are very less in the exhaust muffler shell with the muffler shell 400
when compared to the vibrations in the conventional exhaust muffler 100 with the
25 muffler shell 104.
[0063] The stepped muffler shell 400 improves vibration levels from 25% to
60%.
12
TECHNICAL ADVANTAGES
[0064] The present disclosure proposes an exhaust muffler for reducing
exhaust noise.
[0065] The present disclosure proposes a muffler shell that reduces the
5 vibration in an exhaust muffler.
[0066] The present disclosure proposes a muffler shell with increased local
stiffness.
[0067] The present disclosure proposes a muffler shell that reduces both, low
and high frequency vibrations.
10 [0068] Furthermore, each of the appended claims defines a separate
invention, which for infringement purposes is recognized as including equivalents
to the various elements or limitations specified in the claims. Depending on the
context, all references below to the “invention” may in some cases refer to certain
specific embodiments only. In other cases, it will be recognized that references to
15 the “invention” will refer to subject matter recited in one or more, but not
necessarily all, of the claims.
[0069] Groupings of alternative elements or embodiments of the invention
disclosed herein are not to be construed as limitations. Each group member can be
referred to and claimed individually or in any combination with other members of
20 the group or other elements found herein. One or more members of a group can be
included in, or deleted from, a group for reasons of convenience and/or
patentability. When any such inclusion or deletion occurs, the specification is
herein deemed to contain the group as modified thus fulfilling the written
description of all groups used in the appended claims.
25 [0070] Furthermore, those skilled in the art can appreciate that the
terminology used herein is for the purpose of describing particular embodiments
only and is not intended to be limiting of the present disclosure. It will be
13
appreciated that several of the above-disclosed and other features and functions,
or alternatives thereof, may be combined into other systems or applications.
Various presently unforeseen or unanticipated alternatives, modifications,
variations, or improvements therein may subsequently be made by those skilled in
5 the art without departing from the scope of the present disclosure as encompassed
by the following claims.
[0071] The claims, as originally presented and as they may be amended,
encompass variations, alternatives, modifications, improvements, equivalents, and
substantial equivalents of the embodiments and teachings disclosed herein,
10 including those that are presently unforeseen or unappreciated, and that, for
example, may arise from applicants/patentees and others.
[0072] While the foregoing describes various embodiments of the present
disclosure, other and further embodiments of the present disclosure may be
devised without departing from the basic scope thereof. The scope of the present
15 disclosure is determined by the claims that follow. The present disclosure is not
limited to the described embodiments, versions or examples, which are included
to enable a person having ordinary skill in the art to make and use the invention
when combined with information and knowledge available to the person having
ordinary skill in the art.
20
14
List of Reference numerals of the present invention as disclosed in fig. 6
onwards
1. 400: Muffler shell
2. 402: Front conical frustum shape member
5 3. 404: End portion of the front conical frustum shape member
4. 406: Base portion of the front conical frustum shape member
5. 404a: Circular plate
6. 408: Rear conical frustum shape member
7. 410: End portion of the rear conical frustum shape member
10 8. 410a: Circular plate
9. 412: Base portion of the front conical frustum shape member
10. d: Diameter of end portion of the front and rear conical frustum shape
members
11. D: Diameter of base portion of the front and rear conical frustum shape
15 members
12. 414: Steps
13. 416: Exhaust pipe

We claim:

1. An exhaust muffler (500) with a muffler shell (400) in an exhaust gas
system, the muffler shell (400) comprising:
a front conical frustum shape member (402) having an end portion
5 (404) and a base portion (406); and
a rear conical frustum shape member (408) having an end portion
(410) and a base portion (412),
wherein the base portion (406) of the front conical frustum shape
member (402) is joined with the base portion (412) of the rear conical
10 frustum shape member (408) to define structure of the muffler shell (400).
2. The exhaust muffler (500) as claimed in claim 1, wherein the front conical
frustum shape member (402) is identical with the rear conical frustum shape
member (408).
15
3. The exhaust muffler (500) as claimed in claim 1, wherein diameter of the
front conical frustum shape member (402) increases from the end portion
(404) towards the base portion (406).
20 4. The exhaust muffler (500) as claimed in claim 1, wherein diameter of the
rear conical frustum shape member (408) increases from the end portion
(410) towards the base portion (412).
5. The exhaust muffler (500) as claimed in claim 3, wherein the end portion
25 (404) of the front conical frustum shape member (402) and the end portion
(410) of the rear conical frustum shape member (408) defines a diameter ‘d’
smaller than diameter ‘D’ of the base portion (406) of the front conical
frustum shape member (402) and the base portion (412) of the rear conical
frustum shape member (408).
30
16
6. The exhaust muffler (500) as claimed in claim 1, wherein the muffler shell
is configured to cover an exhaust pipe (416).
7. The exhaust muffler (500) as claimed in claim 1, wherein outer surface of
5 the muffler shell (400) defines steps (414) to increase local stiffness of the
muffler shell (400).
8. The exhaust muffler (500) as claimed in claim 1, wherein a circular plate
(404a, 410a) has a hole to receive an exhaust pipe (416) provided at the end
10 portions (406, 410) of the muffler shell (400).
9. The exhaust muffler (500) as claimed in claim 8, wherein the circular plate
(404a, 410a) is welded with the end portions (404, 410) of the muffler shell
(400).
15
10. The exhaust muffler (500) as claimed in claim 1, wherein the front conical
frustum shape member (402) and the rear conical frustum shape member
(408) are joined by means of welding.