Note: Descriptions are shown in the official language in which they were submitted.
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Background and Summary of the Invention
This invention relates to exhaust systems and, in
particular, to mufflers for quieting the exhaust noise of a
vehicle engine. More particularly, this invention relates
to mufflers having outer shells and a single inner
cartridge situated between the outer shells to define a
plurality of tubes and chambers between the outer shells.
It is known to construct mufflers using stamp-
formed outer shells and inner plates. See, for example,
U.S. Patent Nos. 5,252,788 to Emrick et al.; 5,229,557 to
Allman et al.; 5,147,987 to Richardson et al.; 5,004,069 to
Van Blaircum et al.; 4,941,545 to Wilcox et al.; 4,860,853
to Moring; 4,736,817 to Harwood; and Re. 33,370 to Harwood.
Stamp-formed mufflers include a plurality of
chambers and tubes formed between the stamped outer shells
and inner plates. The chambers and tubes direct exhaust
gas of the vehicle engine through the muffler in a desired
manner to quiet the exhaust noise produced by the vehicle
engine effectively.
Various techniques have been used to form tubes
and chambers in stamp-formed mufflers. For example, in
U.S. Patent Nos. 5,229,557 to Allman et al.; 5,147,987 to
Richardson et al.; and 4,941,545 to Wilcox et al., drop-in
baffles were placed between the inner plates and outer
shells to form chambers within the muffler. Also, for
example, in U.S. Patent Nos. 4,860,853 to Moring; 4,736,817
to Harwood; 5,004,069 to Van Blaircum et al.; and Re 33,370
to Harwood the outer shells are "deep-drawn" to define a
crease in the outer shells that extends inwardly to abut
the inner plates and form chambers within the muffler. In
U.S. Patent No. 5,252,788 to Emrick et al., the inner
plates are deep-drawn outward to abut the outer shells that
are deep-drawn inward to form chambers within the muffler.
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The sheet metal deep-drawing process is an expensive
manufacturing process that is difficult to perform with
accuracy on stainless steel sheet metal.
4Jhat is needed is a stamp-formed muffler that is
manufactured without using a deep-drawing process on the
outer shells to define chambers in the muffler. A stamp-
formed muffler having a minimum number of parts is also
needed. A muffler manufactured without a deep-drawing
process to define chambers and with a minimum number of
parts would reduce the time and cost of manufacturing and
assembly.
According to the present invention, a muffler is
provided having a top outer shell, a bottom outer shell,
and a drop-in inner cartridge. The top outer shell
includes a top wall, a lip, spaced-apart first and second
side walls extending between the top wall and the lip, and
spaced-apart first and second end walls extending between
the first and second side walls, top wall, and lip. The
bottom outer shell includes a bottom wall, a lip, spaced-
apart first and second side walls extending between the
bottom wall and the lip, and spaced-apart first and second
end walls extending between the first and second side
walls, bottom wall, and lip.
The lips of the top and bottom outer shells
cooperate to define an interior cartridge-receiving
chamber. The lip of the top outer shell abuts the lip of
the bottom outer shell to define a seam that includes an
inner surface facing into the interior cartridge-receiving
chamber. The drop-in inner cartridge is positioned to lie
between the top and bottom outer shells. The drop-in inner
cartridge extends from the first side wall of the top'and
bottom outer shells to the second side wall of the top and
bottom outer shells. The drop-in inner cartridge further
includes an outer edge abutting the inner surface of the
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seam to cause the drop-in inner cartridge to lie wholly
within the interior cartridge-receiving chamber.
In a preferred embodiment of the present
invention, the drop-in inner cartridge includes an inlet
tube, an outlet tube, and first, second, and third baffles
extending between the inlet and outlet tubes. The inlet
and outlet tubes and the first, second, and third baffles
define first, second, third, and fourth chambers. Various
apertures and louvers are formed in the inlet tube, outlet
tube, and baffles. Gas flow entering the inlet tube passes
from the inlet tube serially through the first chamber,
second chamber, third chamber, and fourth chamber and into
the outlet tube.
In another preferred embodiment of the present
invention, the drop-in inner cartridge includes first,
second, and third baffles to define first and second
helmholtz tuning chambers and first and second flow-through
chambers. Gas flow entering the inlet tube passes from the
inlet tube serially through the first and second flow-
through chambers and into the outlet tube. The first flow-
through tuning chamber is in direct communication with the
first Helmholtz tuning chamber and the second flow-through
tuning chamber is in direct communication with the second
Helmholtz tuning chamber.
In another preferred embodiment of the present
invention, the drop-in inner cartridge includes a single
baffle extending between the inlet tube and the outlet tube
to define first and second chambers. Gas flow entering the
inlet tube passes from the inlet tube serially through the
first and second chambers and into the outlet tube.
In preferred embodiments of the present
invention, the drop-in inner cartridge includes a baffle
system extending between the inlet tube and the outlet
tube. Each of the inlet and outlet tubes include a top
side facing upwardly toward the top outer shell and a
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bottom side facing downwardly toward the bottom outer
shell. The baffle system includes a first side connected
to one of the top and bottom sides of the inlet tube and a
second side connected to the other of the top and bottom
sides of the outlet tube.
In yet another preferred embodiment of the
present invention, the drop-in inner cartridge includes a
plurality of tubes and a baffle connected to the plurality
of tubes. The baffle extends substantially parallel to a
longitudinal axis of the muffler between the first end
walls of the top and bottom outer shells and the second end
walls of the top and bottom outer shells. The baffle also
extends between the top wall of the top outer shell and the
bottom wall of the bottom outer shell to lie substantially
perpendicular to the top wall of the top outer shell and
the bottom wall of the bottom outer shell.
In most embodiments of the present invention, the
muffler assembly consists of only three pieces. The three-
piece muffler assembly consists of only a stamped top outer
shell, a stamped bottom outer shell, and a drop-in inner
cartridge situated between the top and bottom stamped outer
shells.
In some embodiments of the present invention, one
or more tuning throats may be connected to one or more of
the baffles and extend into a chamber. The tuning throat
provides additional tuning to quiet the exhaust gas flow.
In some embodiments of the present invention, the
muffler assembly consists of only two pieces. The two-
piece muffler assembly consists of only a single outer
shell and a single drop-in inner cartridge. The single
outer shell is made from a flat sheet of material using a
stamping process. The stamped single outer shell is then
folded to surround the single drop-in inner cartridge.
In all embodiments of the present invention, no
deep-drawing operations are required to make creases in the
~ rt
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top and bottom stamped outer shells or the drop-in inner
cartridge to define chambers between the stamped outer
shells. The top and bottom stamped outer shells are formed
to include stiffening ribs. However, these stiffening ribs
do not define chambers between the stamped outer shells.
By producing a stamp-formed muffler without using a deep-
drawing process to define chambers, the manufacturing cost
of the muffler is minimized.
A single sheet of material is used to manufacture
the drop-in inner cartridge which provides baffles to
define the chambers and inlet and outlet tubes. The
baffles also provide significant structural support for the
muffler.
The drop-in inner cartridge is made from a single
pre-cut sheet of material according to the following steps.
The various apertures and louver patches present in the
inlet and outlet tubes and the baffles are extruded in the
pre-cut sheet of material. Next, a break-and-fold process
is performed on the single flat sheet of material to form
the baffles. Finally, the sides of the pre-cut sheet of
material are rolled to form the inlet and outlet tubes. In
embodiments of the present invention having a single
baffle, the break-and-fold process is not required.
Additional objects, features, and advantages of
the invention will become apparent to those skilled in the
art upon consideration of the following detailed
description of preferred embodiments exemplifying the best
mode of carrying out the invention as presently perceived.
Brief Desc_r~ption of the Drawinc_~
The detailed description particularly refers to
the accompanying figures in which:
Fig. 1 is an exploded perspective view showing a
three-piece muffler according to the present invention
including top and bottom outer shells having top and bottom
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walls and a drop-in inner cartridge including an inlet
tube, an outlet tube, first, second, and third baffles
extending between the inlet tube and outlet tube, and
various apertures and louvers formed in the tubes and
baffles;
Fig. 2 is an end view of the muffler of Fig. 1,
with portions cutaway, showing the drop-in inner cartridge
situated between the top and bottom stamped shells and the
baffles of the drop-in inner cartridge defining a plurality
of chambers through which exhaust gas travels as the
exhaust gas passes through the muffler;
Fig. 3 is a view taken along line 3-3 of Fig. 1,
with portions cutaway, showing the drop-in inner cartridge
lying in the bottom stamped outer shell and the direction
of exhaust gas flow through the muffler;
Fig. 4 is a sectional view taken along line 4-4
of Fig. 2 showing positioning tabs appended to the drop-in
inner cartridge and abutting the top and bottom stamped
outer shells and the direction of exhaust gas flow through
the muffler;
Figs. 5-7 show various stages in the manufacture
of the drop-in inner cartridge of the embodiment of the
present invention shown in Figs. 1-4;
Fig. 5 is a top plan view of a single pre-cut
sheet that is folded to form into the drop-in inner
cartridge, the single pre-cut sheet being formed to include
various apertures and louvers and configured to facilitate
transformation into the drop-in inner cartridge;
Fig. 6 is a top plan view of the pre-cut sheet of
Fig. 5 showing a partially formed drop-in inner cartridge
after a break-and-fold process is performed on the single
pre-cut sheet to form the first, second, and third baffles;
Fig. 7 is a top plan view of the partially formed
drop-in inner cartridge of Fig. 6 showing the sides of the
partially formed drop-in inner cartridge rolled to form the
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inlet and outlet tubes and the positioning tabs bent into
their proper position to form a completed drop-in inner
cartridge;
Fig. 8 is an exploded perspective view similar to
Fig. 1 of a second preferred embodiment of a muffler
including top and bottom stamped outer shells having top
and bottom walls, a drop-in inner cartridge having inlet
and outlet tubes, first, second, and third baffles, and
various apertures and louvers formed in the tubes and
baffles, and a tuning throat connected to one of the
apertures formed in the drop-in inner cartridge;
Fig. 9 is an end view similar to Fig. 2, with
portions cutaway, showing the baffles of the drop-in inner
cartridge defining first and second Helmholtz tuning
chambers and first and second flow-through chambers, the
tuning throat extending into one of the Helmholtz chambers,
and the flow of exhaust gas through the inlet tube, outlet
tube, and first and second flow-through chambers;
Fig. 10 is a view similar to Fig. 3 taken along
line 10-10 of Fig. 8, with portions cutaway, showing the
drop-in inner cartridge lying in the stamped bottom outer
shell and the direction of exhaust gas flow through the
muf f ler;
Fig. 11 is a sectional view similar to Fig. 4
taken along line 11-11 of Fig. 9 showing positioning tabs
appended to the drop-in inner cartridge and configured to
abut the top and bottom stamped outer shells and the
direction of exhaust gas flow through the muffler;
Figs. 12-14 show various stages in the
manufacture of the drop-in inner cartridge of the
embodiment of the present invention shown in Figs. 8-11;
Fig. 12 is a top plan view similar to Fig. 5 of a
pre-cut sheet that is formed to include various apertures
and louvers and configured to facilitate transformation
into the drop-in inner cartridge;
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Fig. 13 is a top plan view similar to Fig. 6 of
the pre-cut sheet of Fig. 12 showing a partially formed
drop-in inner cartridge after a break-and-fold process is
performed on the single pre-cut sheet to form the first,
second, and third baffles;
Fig. 14 is a top plan view similar to Fig. 7 of
the partially formed drop-in inner cartridge of Fig. 13
showing the sides of the partially formed drop-in inner
cartridge rolled to form the inlet and outlet tubes and the
positioning tabs bent into their proper position to form a
completed drop-in inner cartridge;
Fig. 15 is an exploded perspective view similar
to Figs. 1 and 8 showing another preferred embodiment of a
three-piece muffler according to the present invention
including top and bottom stamped outer shells having top
and bottom walls and a drop-in inner cartridge having an
inlet tube, an outlet tube, a baffle extending between the
inlet tube and outlet tube, and various apertures and
louvers formed in the tubes and baffles;
Fig. 16 is an end view similar to Figs. 2 and 9
of the muffler of Fig. 15, with portions cutaway, showing
the drop-in inner cartridge situated between the top and
bottom stamped outer shells and the baffle defining first
and second chambers through which exhaust gas travels as
the exhaust gas passes through the muffler;
Fig. 17 is a view similar to Figs. 3 and 10 taken
along line 17-17 of Fig. 15, with portions cutaway, showing
the drop-in inner cartridge lying in the stamped bottom
outer shell and showing the direction of exhaust gas flow
through the muffler;
Fig. 18 is a sectional view similar to Figs. 4
and 11 taken along line 4-4 of Fig. 2 showing the direction
of exhaust gas flow through the muffler;
Fig. 19 is a top plan view similar to Figs. 5 and
12 of a single pre-cut sheet that is formed to include
T f
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various apertures and louvers and configured to facilitate
transformation into the inner cartridge;
Fig. 20 is a top plan view similar to Figs. 7 and
14 of the pre-cut sheet of Fig. 19 showing the sides of the
pre-cut sheet rolled to form the inlet and outlet tubes of
a completed drop-in inner cartridge; and
Fig. 21 is a perspective view of a unitary
stamped outer shell showing the unitary stamped outer shell
including a top outer shell half, a bottom outer shell
half, and a hinge connecting the top and bottom outer shell
halves, the hinge permits the top and bottom outer shell
halves to be folded relative to each other to form an
assembled outer shell that is similar to the assembled top
and bottom outer shells as shown in Figs. 2, 4, 9, 11, 16,
and 18.
Detailed Description of the Drawings
A muffler 10 according to the present invention
is shown in Figs. 1-4. Muffler 10 includes a stamped top
outer shell 12, a stamped bottom outer shell 14, a drop-in
inner cartridge 16 situated between top and bottom outer
shells 12, 14, an inlet 15, and an outlet 17 as shown in
Figs. 1-3.
Drop-in inner cartridge 16 is formed from a
single sheet of material. Drop-in inner cartridge 16
includes first, second, and third baffles 18, 20, 22 that
engage top and bottom outer shells 12, 14 to define first,
second, third, and fourth chambers 24, 26, 28, 30 between
top and bottom outer shells 12, 14 as shown, for example,
in Fig. 2.
Exhaust gas flows into inlet 15 of muffler 10 and
serially through first, second, third, and fourth chambers
24, 26, 28, 30 before exiting muffler 10 through outlet 17.
Various apertures and louver patches are formed in baffles
18, 20, 22 to direct the exhaust gas in selected directions
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through muffler 10 to quiet the exhaust noise of a vehicle
engine (not shown).
Top and bottom outer shells 12, 14 include
perimeter edges 32, 34, respectively. Top and bottom outer
shells 12, 14 mate along perimeter edges 32, 34 to secure
drop-in inner cartridge 16 between outer shells 12, 14.
Top outer shell 12 includes a Greaseless top wall
36, first and second end walls 38, 40, first and second
side walls 42, 44 extending between first and second end
walls 38, 40, and a lip 46 appended to side walls 42, 44
and end walls 38, 40. Top wall 36 and first and second
side walls 42, 44 are formed to include stiffening ribs 45.
Stiffening ribs 45 raise the resonant frequency of the top
outer shell 12 which reduces the vibration of and radiated
noise created by top outer shell 12.
Top wall 36 is referred to as a Greaseless top
wall 36 because no deep-drawing processes are performed on
Greaseless top wall 36 to form chambers 24, 26, 28, and 30.
Stiffening ribs 45 serve the limited purpose of reducing
the vibration of and radiated noise created by top outer
shell 12 and do not define chambers between top and bottom
outer shells 12, 14.
First and second end walls 38, 40 and first and
second side walls 42, 44 are appended to Greaseless top
wall 36 and arranged to extend from Greaseless top wall 36
to lip 46 at perimeter edge 32 as shown in Figs. 1 and 2.
First end wall 38 and first side wall 42 are formed to
include an inlet passageway 48 as shown in Figs. 1 and 3.
Second end wall 40 and second side wall 44 are formed to
include an outlet passageway 50. First side wall 42 and
second end wall 40 are formed to include an inlet tube-
receiving chamber (not shown). Second side wall 44 and
first end wall 38 are formed to include an outlet tube-
receiving chamber 54. Inlet tube-receiving chamber (not
shown) and outlet tube-receiving chamber 54 are identical.
r i
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Bottom outer shell 14 likewise includes a
Greaseless bottom wall 56, first and second end walls 58,
60, and first and second side walls 62, 64 extending
between first and second end walls 58, 60, and a lip 66
appended to end walls 58, 60 and side walls 62, 64. Bottom
wall 56 and first and second side walls 62, 64 are formed
to include stiffening ribs 65. Stiffening ribs 65 raise
the resonant frequency of the bottom outer shell 14 which
reduces the vibration of and radiated noise created by top
outer shell 14.
Bottom wall 56 is referred to as a Greaseless
bottom wall 56 because no deep-drawing processes are
performed on Greaseless top wall 36 to form chambers 24,
26, 28, and 30. Stiffening ribs 65 serve the limited
purpose of reducing the vibration of and radiated noise
created by bottom outer shell 14 and do not define chambers
between top and bottom outer shells 12, 14.
First and second end walls 58, 60 and first and
second side walls 62, 64 are appended to Greaseless bottom
wall 56 and arranged to extend from Greaseless bottom wall
56 to lip 66 at perimeter edge 34 as shown in Figs. 1 and
2. First end wall 58 and first side wall 62 are formed to
include an inlet passageway 68 as shown in Figs. 1 and 3.
Second end wall 60 and second side wall 64 are formed to
include an outlet passageway 70. First side wall 62 and
second end wall 60 are formed to include an outlet tube-
receiving chamber 72. Second side wall 64 and first end
wall 58 are formed to include an outlet tube-receiving
chamber 74. Muffler 10 further includes a longitudinal
axis 77 extending from first end walls 38, 58 of top and
bottom outer shells 12, 14 to second end walls 40, 60 of
top and bottom outer shells 12, 14.
When top and bottom outer shells 12, 14 are
assembled, lip 46 of top outer shell 12 extends over lip 66
of bottom outer shell 14 as shown in Figs. 2 and 4. The
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space between top and bottom outer shells 12, 14 defines an
interior cartridge-receiving chamber 76. Lip 46 of top
outer shell 12 includes an inner surface 47 facing into
interior cartridge-receiving chamber 76 and an outer
surface 49 facing away from interior cartridge-receiving
chamber 76 as shown in Fig. 2. Lip 66 of bottom outer
shell 14 includes an inner surface 67 facing into interior
cartridge-receiving chamber 76 and an outer surface 69
facing away from interior cartridge-receiving chamber 76 as
shown in Figs. 2 and 3.
When top and bottom outer shells 12, 14 are
assembled, inner surface 47 of lip 46 abuts outer surface
69 of lip 66 as shown in Figs. 2 and 4. Lips 46, 66 define
a seam 71 having an inner surface 73 that faces into
interior cartridge-receiving chamber 76. Drop-in inner
cartridge 16 includes an outer edge 75 abutting inner
surface 73 of seam 71 to cause drop-in inner cartridge 16
to lie wholly within interior cartridge-receiving chamber
76. Inner surface 67 of lip 66 defines inner surface 73 of
seam 71.
Interior cartridge-receiving chamber 76 includes
first, second, third, and fourth U-shaped channels 78, 80,
82, 84 extending about perimeter edges 32, 34 of top and
bottom outer shells 12, 14. First U-shaped channel 78 is
defined between first end walls 38, 58 of top and bottom
outer shells 12, 14, second U-shaped channel 80 is defined
between first side walls 42, 62 of top and bottom outer
shells 12, 14, third U-shaped channel 82 is defined between
second end walls 40, 60 of top and bottom outer shells 12,
14, and fourth U-shaped channel 84 is defined between
second side walls 44, 64 of top and bottom outer shells 12,
14 .
Drop-in inner cartridge 16 further includes an
inlet tube 86 lying in second U-shaped channel 80 and an
outlet tube 88 lying in fourth U-shaped channel 84. Inlet
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tube 86 extends along an axis 87 and outlet tube 88 extends
substantially parallel to inlet tube 86 along an axis 89.
Axes 87, 89 are also substantially parallel to longitudinal
axis 77. First, second, and third baffles 18, 20, 22
extend between inlet tube 86 and outlet tube 88 as shown in
Figs. 1-3.
Inlet tube 86 includes a first end 90 lying in
inlet passageways 48, 68 of outer shells 12, 14,
respectively, a second end 92 lying in inlet tube-receiving
chambers (not shown), 72 of outer shells 12, 14,
respectively, a top side 91 facing upwardly toward top wall
36 of top outer shell 12, and a bottom side 93 facing
downwardly toward bottom wall 56 of bottom outer shell 14
as shown in Figs. 2 and 3. Outlet tube 88 likewise
includes a first end 94 lying in outlet passageways 50, 70
of outer shells 12, 14, respectively, a second end 96 lying
in outlet tube-receiving chambers 54, 74 of outer shells
12, 14, respectively, a top side 95 facing upwardly toward
top wall 36 of top outer shell 12, and a bottom side 97
facing downwardly toward bottom wall 56 of bottom outer
shell 14 as shown in Figs. 2-4. Inlet passageways 48, 68
form inlet 15 of muffler 10 and outlet passageways 50, 70
form outlet 17 of muffler 10.
First, second, and third baffles 18, 20, 22
define a baffle system 23. Second baffle 20 extends
substantially perpendicular to Greaseless top wall 36 of
top outer shell 12 and Greaseless bottom wall 56 of bottom
outer shell 14 and is sized and shaped to conform to top
and bottom outer shells 12, 14 as shown in Figs. 1-4.
Second baffle 20 includes a perimeter edge 98 and the
entire perimeter edge 98 abuts top and bottom outer shells
12, 14. Second baffle 20 includes first and second U-
shaped end portions 110, 112 and a middle portion 114
extending between first and second U-shaped end portions
110, 112. First U-shaped end portion 110 is situated to
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lie within and conform to the shape of first U-shaped
channel 78 formed between top and bottom outer shells 12,
14 and second U-shaped end portion 112 is situated to lie
within and conform to the shape of third U-shaped channel
82 formed between top and bottom outer shells 12, 14 as
shown in Figs. 1, 3, and 4.
First U-shaped end portion 110 includes a first
end surface 116 abutting first end wall 38 of top outer
shell 12, a second end surface 118 abutting lip 66 of
bottom outer shell 14, and a third end surface 120 abutting
first end wall 58 of bottom outer shell 14 as shown in
Figs. 1, 3, and 4. Second U-shaped end portion 112
likewise includes a first end surface 122 abutting second
end wall 40 of top outer shell 12, a second end surface 124
abutting lip 66 of bottom outer shell 14, and a third end
surface 126 abutting second end wall 60 of bottom outer
shell 14 as shown in Figs. 3 and 4. Middle portion 114
includes a top surface 128 abutting Greaseless top wall 36
of top outer shell 12 and a bottom surface 130 abutting
Greaseless bottom wall 56 of bottom outer shell 14. By
conforming to the shape of top and bottom outer shells 12,
14, second baffle 20 divides interior cartridge-receiving
chamber 76 into two portions 132, 134 as shown in Figs. 2
and 3.
Drop-in inner cartridge 16 further includes
positioning tabs 136 appended to second baffle 20 as shown
in Figs. 1-4. Positioning tabs 136 abut top and bottom
outer shells 12, 14 to assist drop-in inner cartridge 16 in
attaining its proper position within top and bottom outer
shells 12, 14. More specifically, a positioning tab 136 is
appended to each of first and third end surfaces 116, 120,
122, 126 of first and second U-shaped portions 110, 112 of
second baffle 20 to define an included angle 127 of about
90° therebetween as shown, for example, in Fig. 1.
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Drop-in inner cartridge 16 further includes top
and bottom abutting surfaces 138, 140 to assist drop-in
inner cartridge 16 in attaining its proper position within
top and bottom outer shells 12, 14 and sealing any gap
between second baffle 20 and top and bottom shells 12, 14.
Top abutting surface 138 extends parallel to Greaseless top
wall 36 of top outer shell 12, perpendicular to second
baffle 20, and between second and third baffles 20, 22 and
abuts top outer shell 12 as shown in Fig. 2. Bottom
abutting surface 140 extends parallel to top abutting
surface 138 and Greaseless bottom wall 56 of bottom outer
shell 14, perpendicular to second baffle 20, and between
first and second baffles 18, 20 and abuts bottom outer
shell 14 as shown in Fig. 2. Top and bottom abutting
surfaces 138, 140 engage a portion of top and bottom outer
shells 12, 14, respectively, that is situated between
stiffening ribs 45, 65, respectively, as shown in Fig. 2.
Top and bottom abutting surfaces 138, 140 must engage a
flat surface to completely seal all gaps between second
baffle 20 and top and bottom shells 12, 14. In alternative
embodiments of the present invention, the stiffening ribs
may be formed in any location on the top and bottom outer
shells so long as the top and bottom abutting surfaces
engage a flat surface to completely seal all gaps between
the second baffle and the top and bottom shells.
First baffle 18 separates first portion 132 of
interior cartridge-receiving chamber 76 into first and
second chambers 24, 26 as shown in Fig. 2. First baffle 18
includes a first side 142 appended to top side 91 of inlet
tube 86, a second side 144 appended to bottom abutting
surface 140, a first end portion 146 abutting lip 66 and
first end wall 58 of bottom outer shell 14, and a second
end portion 148 abutting lip 66 and second end wall 60 of
bottom,~outer shell 14 as shown in Figs. 1-3.
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Third baffle 22 similarly separates second
portion 134 of interior cartridge-receiving chamber 76 into
third and fourth chambers 28, 30 as shown in Fig. 2. Third
baffle 22 includes a first side 150 appended to bottom side
97 of outlet tube 88, a second side 152 appended to top
abutting surface 138, a first end portion 154 abutting lip
66 of bottom outer shell 14 and first end wall 38 of top
outer shell 12, and a second end portion 156 abutting lip
66 of bottom outer shell 14 and second end wall 40 of top
outer shell 12. Third baffle 22 extends substantially
parallel to first baffle 18.
Various apertures and louvers are formed in inlet
tube 86, outlet tube 88, first baffle 18, second baffle 20,
and third baffle 22 as shown in Figs. 1-4. In the
embodiment illustrated in Figs. 1-4, bottom side 93 of
inlet tube 86 is formed to include a rectangular-shaped
aperture 158 and a louver patch 160 opening into first
chamber 24 as shown in Figs. 2 and 3. Top side 95 of
outlet tube 88 is similarly formed to include a
rectangular-shaped aperture 162 and a louver patch 164
opening into fourth chamber 30 as shown in Figs. 1-4.
First and third baffles 18, 22 are formed to include round
apertures 166, 168 respectively. Second baffle 20 is
formed to include a round aperture 170 and a louver patch
172 as shown in Figs. 1-4.
Exhaust gas flows in direction 174 into inlet
tube 86 through first end 90 of inlet tube 86 as shown in
Fig. 3. The exhaust gas then flows in direction 176
through either louver patch 160 or rectangular-shaped
aperture 158 of inlet tube 86 into first chamber 24 as
shown in Figs. 2 and 3. The exhaust gas does not exit
second end 92 of inlet tube 86 because inlet tube-receiving
chamber 72 substantially closes second end 92 of inlet tube
86 as shown in Fig. 3. Next, exhaust gas passes in
direction 178 through aperture 166 formed in first baffle
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18 into second chamber 26 as shown in Figs. 2 and 3. The
exhaust gas then travels in direction 180 through either
aperture 170 or louver patch 172 formed in second baffle 20
into third chamber 28 as shown in Figs. 2-4. Next, exhaust
gas flows in direction 182 through aperture 168 formed in
third baffle 22 into fourth chamber 30 as shown in Figs. 2-
4. Exhaust gas then travels in direction 184 through
either rectangular-shaped aperture 162 or louver patch 164
formed in outlet tube 88 as shown in Figs. 2-4. Finally,
exhaust gas exits outlet tube 88 in direction 186 as shown
in Figs. 3 and 4. The exhaust gas does not exit second end
96 of outlet tube 88 because outlet tube-receiving chamber
74 substantially closes second end 96 of outlet tube 88 as
' shown in Figs. 3 and 4.
Drop-in inner cartridge 16 is formed from a pre-
cut sheet 188 of material as shown in Fig. 5. The various
apertures 158, 162, 166, 168, 170 and louver patches 160,
164, 172 of inlet and outlet tubes 86, 88 and baffles 18,
20, 22 are formed in pre-cut sheet 188 using an extrusion
process. A breaking-and-folding process is performed on
pre-cut sheet 188 to form first, second, and third baffles
18, 20, 22 as shown in a partially formed inner cartridge
190 in Fig. 6. Positioning tabs 136 are bent into their
proper position as shown also in partially formed drop-in
inner cartridge 190 in Fig. 6. Pre-cut sheet 188 includes
first and second sides 192, 194 that are rolled to form
inlet and outlet tubes 86, 88, respectively, as shown in
completed drop-in inner cartridge 16 in Fig. 7.
Another preferred embodiment of a muffler 210
according to the present invention is shown in Figs. 8-il.
Top and bottom outer shells 12, 14 of muffler 10, shown in
Figs. 1-4, are identical to top and bottom outer shells 12,
14 of muffler 210 shown in Figs. 8-11. All components of
top and bottom outer shells 12, 14 are numbered identically
in mufflers 10, 210.
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Muffler 210 includes a drop-in inner cartridge
212 having an inlet tube 214, an outlet tube 216, and a
baffle system 215 as shown in Figs. 8-11. Drop-in inner
cartridge 212 is identical to drop-in inner cartridge 16 of
muffler 10 except that the apertures and louver patches
formed in inlet and outlet tubes 214, 216 of drop-in inner
cartridge 212 are formed on the opposite side of inlet and
outlet tubes 214, 216 as compared to inlet and outlet tubes
86, 88 of drop-in inner cartridge 16. By forming the
apertures and louver patches on the opposite side of the
inlet and outlet tubes 214, 216, the flow of exhaust gas
through muffler 210 is different than the flow of exhaust
gas through muffler 10.
Baffle system 215 of drop-in inner cartridge 212
includes a first baffle 218, a second baffle 220, and a
third baffle 222 as shown in Figs. 8-11. Inlet and outlet
tubes 214, 216 and baffles 218, 220, 222 define first and
second flow-through chambers 224, 226 and first and second
Helmholtz tuning chambers 228, 230 as shown, for example,
in Fig. 8.
Inlet tube 214 includes a first end 232 lying in
inlet passageways 48, 68 of top and bottom outer shells 12,
14, respectively, a second end 234 lying in inlet tube-
receiving chambers (not shown), 72 of top and bottom outer
shells 12, 14, respectively, a top side 231 facing upwardly
toward top wall 36 of top outer shell 12, and a bottom side
233 facing downwardly toward bottom wall 56 of bottom outer
shell 14 as shown in Figs. 9 and 10. Inlet tube 214
extends along an axis 217 as shown, for example, in Figs.
8-10.
Outlet tube 216 likewise includes a first end 236
lying in outlet passageways 50, 70 of top and bottom outer
shells 12, 14, respectively, a second end 238 lying in
outlet tube-receiving chambers 54, 74 of top and bottom
outer shells 12, 14, respectively, a top side 235 facing
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upwardly toward top wall 36 of top outer shell 12, and a
bottom side 237 facing downwardly toward bottom wall 56 of
bottom outer shell 14 as shown in Figs. 10 and 11. Outlet
tube 216 extends along an axis 219 that is parallel to axis
217 of inlet tube 216 and longitudinal axis 77 as shown in
Figs. 8-11.
Second baffle 220 extends substantially
perpendicular to Greaseless top wall 36 of top outer shell
12 and Greaseless bottom wall 56 of bottom outer shell 14
and is sized and shaped to conform to top and bottom outer
shells 12, 14 as shown in Figs. 8-11. Second baffle 220
includes a perimeter edge 239 and the entire perimeter edge
239 abuts top and bottom outer shells 12, 14. Second
baffle 220 includes first and second U-shaped end portions
240, 242 and a middle portion 244 extending between first
and second U-shaped end portions 240, 242. First U-shaped
end portion 240 is situated to lie within and conform to
the shape of first U-shaped channel 78 defined by top and
bottom outer shells 12, 14 and second U-shaped end portion
242 is situated to lie within and conform to the shape of
third U-shaped channel 82 defined by top and bottom outer
shells 12, 14.
First U-shaped end portion 240 includes a first
end surface 246 abutting first end wall 38 of top outer
shell 12, a second end surface 248 abutting lip 66 of
bottom outer shell 14, and a third end surface 250 abutting
first end wall 58 of bottom outer shell 14 as shown in
Figs. 8, 10, and il. Second U-shaped end portion 242
likewise includes a first end surface 252 abutting second
end wall 40 of top outer shell 12, a second end surface 254
abutting lip 66 of bottom outer shell 14, and a third end
surface 256 abutting second end wall 60 of bottom outer
shell 14 as shown in Figs. 10 and 11.
Middle portion 244 includes a top surface 258
abutting Greaseless top wall 36 of top outer shell 12 and a
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bottom surface 260 abutting Greaseless bottom wall 56 of
bottom outer shell 14. By conforming to the shape of top
and bottom outer shells 12, 14, second baffle 220 divides
interior cartridge-receiving chamber 76 into first and
second portions 262, 264 as shown in Figs. 9 and 11.
Drop-in inner cartridge 212 further includes
positioning tabs 266 appended to second baffle 220.
Positioning tabs 266 abut top and bottom outer shells 12,
14 to assist drop-in inner cartridge 212 in attaining its
proper position within top and bottom outer shells 12, 14.
More specifically, a positioning tab 266 is appended to
each of first and third end surfaces 246, 250, 252, 256 of
first and second U-shaped portions 240, 242 to define an
included angle 257 of about 90° therebetween as shown, for
example, in Fig. 8.
Drop-in inner cartridge 212 further includes top
and bottom abutting surfaces 268, 27o to assist drop-in
inner cartridge 212 in attaining its proper position within
top and bottom outer shells 12, 14 and sealing any gap
between second baffle 220 and top and bottom outer shells
12, 14. Top abutting surface 268 extends between second
and third baffles 220, 222 and abuts top outer shell 12 as
shown in Fig. 9. Bottom abutting surface 270 extends
between first and second baffles 218, 220 and abuts bottom
outer shell 14 as shown in Fig. 9. Top and bottom abutting
surfaces 268, 270 engage a portion of top and bottom outer
shells 12, 14, respectively, that is situated between
stiffening ribs 45, 65, respectively, as shown in Fig. 9.
Top and bottom abutting surfaces 268, 270 must engage a
flat surface to completely seal all gaps between second
baffle 220 and top and bottom shells 12, 14. In
alternative embodiments of the present invention, the
stiffening ribs may be formed in any location on the top
and bottom outer shells so long as the top and bottom
abutting surfaces engage a flat surface to completely seal
T
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all gaps between the second baffle and the top and bottom
shells.
First baffle 218 separates first portion 262 of
interior cartridge-receiving chamber 76 into first flow-
s through chamber 224 and first Helmholtz tuning chamber 228
as shown in Fig. 9. First baffle 218 includes a first side
272 appended to top side 231 of inlet tube 214, a second
side 274 appended to bottom abutting surface 270, a first
end portion 276 abutting lip 66 and first end wall 58 of
bottom outer shell 14, and a second end portion 278
abutting lip 66 and second end wall 60 of bottom outer
shell 14 as shown in Figs. 8 and 10.
Third baffle 222 similarly separates second
portion 264 of interior cartridge-receiving chamber 76 into
second flow-through chamber 226 and second Helmholtz tuning
chamber 230 as shown in Fig. 9. Third baffle 222 includes
a first side 280 appended to bottom side 237 of outlet tube
216, a second side 282 appended to top abutting surface
268, a first end portion 284 abutting lip 66 of bottom
outer shell 14 and first end wall 38 of top outer shell 12,
and a second end portion 286 abutting lip 66 of bottom
outer shell 14 and second end wall 40 of top outer shell 12
as shown in Figs. 8 and 10. Third baffle 222 extends
substantially parallel to first baffle 218.
Various apertures and louvers are formed in inlet
tube 214, outlet tube 216, first baffle 218, second baffle
220, and third baffle 222 as shown in Figs. 8-11. In the
illustrated embodiment of Figs. 8-11, top side 231 of inlet
tube 214 is formed to include a rectangular-shaped aperture
288 and a louver patch 290 opening into first flow-through
chamber 224 as shown in Figs. 8 and 10. Bottom side 237 of
outlet tube 216 is similarly formed to include a
rectangular-shaped aperture 292 and a louver patch 294
opening into second flow-through chamber 226 as shown in
Figs. 9-11. First and third baffles 218, 222 are formed to
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include a round aperture 296, 298, respectively. Second
baffle 220 is formed to include a round aperture 310 and a
louver patch 312 as shown in Figs. 8-11.
Exhaust gas flows in direction 314 into inlet
tube 214 as shown in Fig. 10. The exhaust gas then flows
in direction 316 through either louver patch 290 or
rectangular-shaped aperture 288 of inlet tube 214 into
first flow-through chamber 224 as shown in Figs. 9 & 10.
The exhaust gas does not exit second end 234 of inlet tube
214 because inlet tube-receiving chamber 72 substantially
closes second end 234 of inlet tube 214 as shown in Fig.
10. Next, exhaust gas travels in direction 318 through
either aperture 310 or louver patch 312 formed in second
baffle 220 into second flow-through chamber 226 as shown in
Figs. 9-11. Exhaust gas then travels in direction 320
through either rectangular-shaped aperture 292 or louver
patch 294 formed in outlet tube 216 as shown in Figs. 9-11.
Finally, exhaust gas exits outlet tube 216 in direction 322
as shown in Figs. 10 and 11. The exhaust gas does not exit
second end 238 of outlet tube 216 because the outlet tube-
receiving chamber 74 substantially closes second end 238 of
outlet tube 216 as shown in Figs. 10 and 11.
First helmholtz tuning chamber 228 communicates
with first flow-through chamber 224 through aperture 296
formed in first baffle 218 as shown in Fig. 9. Second
helmholtz tuning chamber 23o communicates with second flow-
through chamber 226 through aperture 298 formed in third
baffle 222 as shown in Fig. 9. First and second helmholtz
tuning chambers 228, 230 provide additional tuning and
quieting of exhaust flow passing through muffler 210.
Muffler 210 further includes a tuning throat 324 secured
within aperture 298 of third baffle 22 and arranged to
extend into second helmholtz tuning chamber 230 to provide
additional tuning and quieting of exhaust flow passing
through muffler 210.
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Drop-in inner cartridge 212 is formed from a pre-
cut sheet 326 of material as shown in Fig. 12. The various
apertures 288, 292, 296, 298, 310 and louver patches 290,
294, 312 of inlet and outlet tubes 214, 216 and baffles
218, 220, 222 are formed in pre-cut sheet 326 using an
extrusion process. A breaking-and-folding process is
performed on pre-cut sheet 326 to form first second, and
third baffles 218, 220, 222 as shown in a partially formed
inner cartridge 328 in Fig. 13. Positioning tabs 266 are
bent into their proper position as shown also in partially
formed drop-in inner cartridge 328 in Fig. 13. Pre-cut
sheet 326 includes first and second sides 330, 332 that are
rolled to form inlet and outlet tubes 214, 216,
respectively, as shown in completed drop-in inner cartridge
212 in Fig. 14.
Another preferred embodiment of a muffler 350
according to the present invention is shown in Figs. 15-18.
Top and bottom outer shells 12, 14 of mufflers 10, 210
shown in Figs. 1-4 and 8-11, respectively, are identical to
top and bottom outer shells 12, 14 of muffler 350 shown in
Figs. 15-18. All components of top and bottom outer shells
12, 14 are numbered identically in mufflers 10, 210, 350.
Muffler 350 includes an drop-in inner cartridge
352 having an inlet tube 354, an outlet tube 356, and a
baffle system 357. Baffle system 357 includes a single
baffle 358 extending between inlet tube 354 and outlet tube
356. Baffle 358 and inlet and outlet tubes 354, 356 define
first and second chambers 360, 362 in interior cartridge-
receiving chamber 76 as shown in Figs. 16 and 18. Baffle
358 and bottom wall 56 define an included angle 426
therebetween and baffle 358 and top wall 36 define an
included angle 428 therebetween as shown, for example, in
Fig. 16.
Inlet tube 354 includes a first end 364 lying in
inlet passageways 48, 68 of outer shells 12, 14,
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respectively, a second end 366 lying in inlet tube-
receiving chambers (not shown), 72 of outer shells 12, 14,
respectively, a top side 363 facing upwardly toward top
wall 36 of top outer shell 12, and a bottom side 365 facing
downwardly toward bottom wall 56 of bottom outer shell 14
as shown in Figs. 16 and 17. Top side 363 of inlet tube
356 is formed to include a rectangular-shaped aperture 368
and a louver patch 370 opening into first chamber 360 as
shown in Figs. 15-17. Inlet tube 354 extends along an axis
430 as shown, for example, in Figs. 15-17.
Outlet tube 356 likewise includes a first end 372
lying in outlet passageways 50, 70 of top and bottom outer
shells 12, 14, respectively, a second end 374 lying in
outlet tube-receiving chambers 54, 74 of top and bottom
outer shells 12, 14, respectively, a top side 371 facing
upwardly toward top wall 36 of top outer shell 12, and a
bottom side 373 facing downwardly toward bottom wall 56 of
bottom outer shell 14 as shown in Figs. 17 and 18. Bottom
side 373 of outlet tube 356 is formed to include a
rectangular-shaped aperture 376 and a louver patch 378
opening into second chamber 362 as shown in Figs. 15-18.
Outlet tube 356 extends along an axis 432 that is parallel
to axis 430 of inlet tube and longitudinal axis 77 as
shown, for example, in Figs. 15-18.
Inlet tube 354, outlet tube 356, and baffle 358
abut inner surface 67 of lip 66 of bottom outer shell 14
along the entire perimeter edge 34 of bottom outer shell 14
to divide interior cartridge-receiving chamber 76 into
first and second chambers 360, 362 as shown in Figs. 16 and
18. Baffle 358 includes a first end 392 appended to inlet
tube 354, a second end 394 appended to outlet tube 356, and
an aperture 380 to permit exhaust gas to flow from first
chamber 360 to second chamber 362 as shown in Figs. 15-17.
Exhaust gas flows in direction 382 into inlet
tube 354 as shown in Fig. 17. The exhaust gas then flows
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in direction 384 through either louver patch 370 or
rectangular-shaped aperture 368 of inlet tube 354 into
first chamber 360 as shown in Figs. 16 and 17. The exhaust
gas does not exit second end 366 of inlet tube 354 because
the inlet tube-receiving chamber 72 substantially closes
second end 366 of inlet tube 354 as shown in Fig. 17.
Next, exhaust gas travels in direction 386 through aperture
380 formed in baffle 358 into second chamber 362 as shown
in Figs. 16 and 17. Exhaust gas then travels in direction
388 into outlet tube 356 through either rectangular-shaped
aperture 376 or louver patch 378 formed in outlet tube 356
as shown in Figs. 16-18. Finally, exhaust gas exits outlet
tube 356 in direction 390 as shown in Figs. 17 and 18. The
exhaust gas does not exit second end 374 of outlet tube 356
because the outlet tube-receiving chamber 74 substantially
closes second end 374 of outlet tube 356 as shown in Figs.
17 and 18.
Drop-in inner cartridge 352 of muffler 350 is
formed from a pre-cut sheet of material 396. Apertures
368, 376, and 380 and louver patches 370, 378 are formed in
pre-cut sheet 396 of material in an extrusion process (not
shown). Pre-cut sheet of material 396 includes first and
second sides 397, 398 that are rolled to form inlet and
outlet tubes 354, 356. The manufacture of drop-in inner
cartridge 352 does not include a breaking-and-folding step
as required in the manufacture of drop-in inner cartridge
16 of muffler 10 and drop-in inner cartridge 212 in the
manufacture of muffler 210.
The location and number of apertures and louver
patches in the illustrated embodiments of the present
invention were selected for a particular application to
quiet the noise of exhaust gas produced by a particular
vehicle engine (not shown) flowing through mufflers 10,
210, 350. In the illustrated embodiments, all apertures
formed in the inlet tubes, outlet tubes, and baffles have
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an area of 3.14 in2 (20.3 cmj). In alternative embodiments
of the present invention, the number, size, and location of
apertures, louver patches, or other means for permitting
exhaust gas to pass through tubes and baffles may be
selected for the particular application to minimize the
exhaust noise of a particular vehicle engine.
In the illustrated embodiments of the present
invention, a single tuning throat 324 was provided in
muffler 210 as shown in Figs. 8-11. In alternative
embodiments of the present invention, one or more tuning
throats may be provided in any of the illustrated mufflers
if needed to obtain a desired tuning of the noise of the
exhaust gas flowing through the muffler.
Mufflers 10, 210, 350 are assembled as follows.
A drop-in inner cartridge 16, 212, 352 is inserted into
bottom outer shell 14. Top outer shell 12 is then mated
with bottom outer shell 14 so that drop-in inner cartridge
16 is situated in interior cartridge-receiving chamber 76.
Lip 46 of top outer shell 12 overlaps lip 66 of bottom
outer shell 14 to provide three layer metal contact between
top and bottom outer shells 12, 14 and one of inlet and
outlet tubes 86, 88, 214, 216, 354, 356 along perimeter
edges 32, 34 where lips 46, 66 are adjacent to inlet and
outlet tubes 86, 88, 214, 216, 354, 356 and two layer metal
contact between lips 46, 66 of top and bottom outer shells
12, 14 along the remaining portion of perimeter edges 32,
34. These surfaces (lips 46, 66, inlet tubes 86, 214, 354,
and outlet tubes 88, 216, 356) are laser welded along a
longitudinal plane defined by perimeter edges 32, 34 to
form a leak free unit with the exception of inlet 15 to
receive exhaust gas and outlet 17 to dispense exhaust gas.
Laser welding is also performed to bond Greaseless top wall
36 to top abutting surfaces 138, 268 and Greaseless bottom
wall 56 to bottom abutting surfaces 140, 270. The
completed muffler 10, 210, 350 is then welded into the
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exhaust system assembly (not shown). The manufacturing
process for muffler 10, 210, 350 includes a minimum of
components and manpower related steps compared to that of a
conventional muffler (not shown).
An alternative embodiment of an outer shell is
unitary stamped outer shell 410 as shown in Fig. 21.
Unitary outer shell 410 is made from a single stamped piece
of material. Embodiments of the present invention using
unitary outer shell 410 and a unitary inner cartridge
comprise a two-piece muffler assembly.
Unitary shell 410 includes a top shell half 412,
a bottom shell half 414, and a hinge 416. Except for hinge
416, unitary outer shell 410 is almost identical to top and
bottom outer shells 12, 14 of mufflers 10, 210, 350 shown
in Figs. 1-4, 8-11, and 15-18, respectively. All
components of unitary outer shell 410 that are identical to
components of top and bottom outer shells 12, 14 of
mufflers 10, 210, 350 are numbered identically. Components
of unitary outer shell 410 that differ from components of
top and bottom outer shells 12, 14 of mufflers 10, 210, 350
will be identified by a different reference number.
Hinge 416 permits top and bottom shell halves
412, 414 to be folded about an outer shell folding axis 418
in direction 420 as shown in Fig. 21. Top shell half 412
includes a perimeter mating edge 422 and bottom shell half
414 includes a perimeter mating edge 424. Top and bottom
shell halves 412, 414 are folded about outer shell folding
axis 418 until perimeter mating edge 422 of top shell half
412 engages perimeter mating edge 424 of bottom shell half
414. In alternative embodiments of the present invention,
the top and bottom shell halves may include lips such as
lips 46, 66 of top and bottom outer shells 12, 14 shown,
for example, in Figs. 1, 2, and 4.
Before the top and bottom shell halves 412, 414
are folded about outer shell folding axis 418, a drop-in
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inner cartridge such as drop-in inner cartridges 16, 212,
352 is placed in bottom outer shell half 412. When top and
bottom shell halves 412, 414 are folded so that perimeter
mating edges 422, 424 of top and bottom shell halves 412,
414, respectively, engage, the drop-in inner cartridge is
situated within unitary outer shell 410 between top and
bottom shell halves 412, 414. The perimeter mating edges
422, 424 are welded together and the drop-in inner
cartridge is welded to the unitary outer shell 410.
In presently preferred embodiments of the present
invention, top and bottom outer shells 12, 14 and drop-in
inner cartridges 16, 212, 352 are made of 400 series
stainless steel. In alternative embodiments of the present
invention, the stamped outer shells and drop-in inner
cartridges can be made of another metal material, a
composite material, or a plastics material.
No deep-drawing operations are required to form
the chambers defined between the top and bottom outer
shells 12, 14. In addition, a single sheet of material is
used to manufacture the drop-in inner cartridge 16, 212,
352, which provides baffles to define chambers, inlet and
outlet tubes, and structural support.
Although this invention has been described in
detail with reference to certain embodiments, variations
and modifications exist within the scope and spirit of the
invention as described and as defined in the following
claims.
