U.S. patent application number 10/952211 was filed with the patent office on 2006-03-30 for muffler and heat shield assembly.
Invention is credited to David J. Leehaug.
Application Number | 20060065480 10/952211 |
Document ID | / |
Family ID | 36097741 |
Filed Date | 2006-03-30 |
United States Patent
Application |
20060065480 |
Kind Code |
A1 |
Leehaug; David J. |
March 30, 2006 |
Muffler and heat shield assembly
Abstract
A muffler assembly includes an outer shell defining an internal
cavity that extends between first and second ends. A first end cap
is attached to the first end and a second end cap is attached to
the second end. The first and second end caps provide a
substantially enclosed internal cavity within the outer shell. A
heat shield extends along a length of the outer shell and has a
first shield end attached to the first end cap and a second shield
end attached to the second end cap. The first and second shield
ends are deformed around an outer perimeter of the first and second
ends caps, or separate retaining members are used to secure the
first and second shield ends to the first and second end caps.
Inventors: |
Leehaug; David J.;
(Columbus, IN) |
Correspondence
Address: |
CARLSON, GASKEY & OLDS, P.C.
400 WEST MAPLE ROAD
SUITE 350
BIRMINGHAM
MI
48009
US
|
Family ID: |
36097741 |
Appl. No.: |
10/952211 |
Filed: |
September 28, 2004 |
Current U.S.
Class: |
181/283 ;
181/282 |
Current CPC
Class: |
F01N 13/18 20130101;
F01N 2450/20 20130101; F01N 2450/18 20130101; F01N 13/1872
20130101; F01N 2260/10 20130101; F01N 13/1855 20130101; F01N 13/185
20130101; F01N 2450/24 20130101; F01N 2260/18 20130101; F01N 13/14
20130101; F01N 2450/22 20130101 |
Class at
Publication: |
181/283 ;
181/282 |
International
Class: |
F01N 7/08 20060101
F01N007/08; F01P 1/08 20060101 F01P001/08; F01N 7/18 20060101
F01N007/18 |
Claims
1. A muffler assembly comprising: an outer shell extending between
first and second ends; a first end cap attached to said first end;
a second end cap attached to said second end; and a heat shield
extending along a length of said outer shell wherein a first shield
end is mounted over said first end cap at a first attachment
interface and a second shield end is mounted over said second end
cap at a second attachment interface.
2. The muffler assembly according to claim 1 wherein said first and
second end caps are attached to said first and second ends at a
spun attachment interface with said first shield end engaging an
external surface of said first end cap and said second shield end
engaging an external surface of said second end cap.
3. The muffler assembly according to claim 2 wherein said first
shield end includes a first deformed portion to define said first
attachment interface and said second shield end includes a second
deformed portion to define said second attachment interface and
wherein said first and second deformed portions are deformed over
said spun attachment interface.
4. The muffler assembly according to claim 2 including a first
retaining ring cooperating with said first shield end to define
said first attachment interface and a second retaining ring
cooperating with said second shield end to define said second
attachment interface.
5. The muffler assembly according to claim 4 wherein said first
retaining ring extends continuously about an outer perimeter of
said first end cap and said second retaining ring extends
continuously about an outer perimeter of said second end cap, said
first retaining ring directly engaging said first shield end and
said spun attachment interface and said second retaining ring
directly engaging said second shield end and said spun attachment
interface.
6. The muffler assembly according to claim 5 wherein said heat
shield surrounds only an upper portion of said outer shell with a
lower surface of a center portion, said heat shield being spaced
apart from an external surface of said outer shell to define a
gap.
7. The muffler assembly according to claim 2 including at least one
first retaining clip securing said first shield end to said first
end cap to define said first attachment interface and at least one
second retaining clip securing said second shield end to said
second end cap to define said second attachment interface.
8. The muffler assembly according to claim 7 wherein said first and
second retaining clips are formed from a resilient spring steel
material.
9. The muffler assembly according to claim 7 wherein said at least
one first retaining clip comprises a first plurality of retaining
clips with each of said first plurality of retaining clips securing
said first shield end to said spun attachment interface at said
first end cap and wherein said at least one second retaining clip
comprises a second plurality of retaining clips with each of said
second plurality of retaining clips securing said second shield end
to said spun attachment interface at said second end cap.
10. The muffler assembly according to claim 9 wherein said heat
shield surrounds only an upper portion of said outer shell with a
lower surface of a center portion, said heat shield being spaced
apart from an external surface of said outer shell to define a gap
and wherein said first and second pluralities of retaining clips
are spaced apart from each other about an outer perimeter of said
heat shield.
11. The muffler assembly according to claim 7 wherein said first
end cap includes at least one first retention feature that
cooperates with said at least one first retaining clip to fix said
at least one first retaining clip to said first end cap and wherein
said second end cap includes at least one second retention feature
that cooperates with said at least one second retaining clip to fix
said at least one second retaining clip to said second end cap.
12. The muffler assembly according to claim 2 wherein said heat
shield includes a plurality of convolutes spaced apart from each
other along a length of said heat shield.
13. The muffler assembly according to claim 12 wherein said heat
shield defines a longitudinal axis extending along the length of
said heat shield and wherein each convolute comprises a raised
accordion projection formed on an upper surface of said heat shield
with each of said raised accordion projections extending in a
direction transverse to said longitudinal axis.
14. The muffler assembly according to claim 2 wherein said heat
shield includes a first shield component and a second shield
component secured to said first shield component with an adjustable
shield attachment interface.
15. The muffler assembly according to claim 14 wherein said
adjustable shield attachment interface includes at least one
longitudinal slot being formed in one of said first and second
shield components and at least one fastener extending through said
at least one longitudinal slot to secure said first and second
shield components to each other.
16. The muffler assembly according to claim 15 wherein said at
least one fastener is linearly movable within said at least one
longitudinal slot to adjust an overall length of said heat shield
within a predetermined overall length range.
17. The muffler assembly according to claim 14 wherein said first
and second shield components each include a plurality of stiffening
ribs extending outwardly from an upper surface of said first and
second shield components.
18. The muffler assembly according to claim 1 wherein said first
attachment interface is different than said second attachment
interface.
19. A method for assembling at heat shield to a muffler comprising:
providing an outer shell having a first end cap attached to a first
shell end and a second end cap attached to a second shell end;
securing a first heat shield end directly over the first end cap at
a first attachment interface; and securing a second heat shield end
directly over the second end cap at a second attachment
interface.
20. The method according to claim 19 including deforming the first
heat shield end about an outer perimeter of said first end cap to
form the first attachment interface and deforming the second heat
shield end about an outer perimeter of said second end cap to form
the second attachment interface.
21. The method according to claim 19 including attaching the first
heat shield end to the first end cap with at least one first
retaining member to form the first attachment interface and
attaching the second heat shield end to the second end cap with at
least one second retaining member to form the second attachment
interface.
Description
TECHNICAL FIELD
[0001] The subject invention relates to a method and apparatus for
attaching a heat shield to a muffler.
BACKGROUND OF THE INVENTION
[0002] A vehicle exhaust system includes a plurality of exhaust
components that handle exhaust gases generated by an internal
combustion engine. A typical exhaust system includes an exhaust
pipe that guides exhaust gases from the internal combustion engine
to a muffler. A tailpipe transfers exhaust gases from the muffler
to external atmosphere. In addition to guiding exhaust gases, the
muffler reduces operational noise levels generated by the internal
combustion engine and exhaust system. The exhaust system can
include other exhaust components for processing exhaust gases or
for reducing noise, such as additional silencers, a catalytic
converter, or a resonator.
[0003] The exhaust components are typically routed from the
internal combustion engine, located near a front portion of a
vehicle, underneath a passenger compartment to a rear portion of
the vehicle where the tailpipe is traditionally located. The
muffler is typically positioned directly underneath the passenger
compartment. As known, the exhaust gases generated by the exhaust
system have high temperatures. Due to the proximity of the muffler
to the passenger component, there is a concern that this heat could
be transferred to the passenger compartment.
[0004] One solution to reduce effects of the heat generated by
exhaust system components has been to install a heat shield between
the muffler and a vehicle structure such as a vehicle floor. Many
different methods have been used to attach the heat shield to the
muffler. One known method involves using bands to secure the heat
shield to the muffler. A banding machine typically secures a band
around the heat shield at each end of the muffler. This method has
some disadvantages. One disadvantage is that the bands may not be
secured tightly enough to the muffler. Loose bands can generate an
annoying rattle sound. Another disadvantage involves the size,
maintenance, and overall cost of the banding machine.
[0005] Another known attachment method uses a weld to attach the
heat shield to the muffler. Typically in this method, the heat
shield is welded directly to an outer shell of the muffler. This
weld interface does not accommodate thermal expansion that occurs
as the muffler heats up and cools down. This can adversely affect
the welds and can even result in weld failures.
[0006] Another known attachment method involves capturing ends of
the heat shield under a spun end of a muffler end cap. A muffler
includes an outer shell with a muffler end cap mounted to each end
of the outer shell. In a spin process, ends of the outer shell and
circumferential edges of the muffler end caps are spun or folded
over each other to provide a secure and permanent attachment
between the muffler end caps and the outer shell. Attempting to
capture another layer of material, i.e. a heat shield end portion,
in the muffler end cap spun end can be disruptive to the assembly
process. Further, muffler leak rate properties can be degraded due
to the additional layer of material at the spun joint.
[0007] Thus, there is a need for an improved attachment interface
between a heat shield and a muffler assembly that can accommodate
thermal expansion without degrading the attachment interfaces, and
which is more reliable than prior attachment interfaces.
SUMMARY OF THE INVENTION
[0008] A muffler assembly includes an outer shell having a first
end cap at one shell end and a second end cap at an opposite shell
end. The first and second end caps are attached to the outer shell
via a spin attachment process. A heat shield extends along a length
of the outer shell and includes a first shield end attached over
the first end cap at a first attachment interface and a second
shield end attached over the second end cap at a second attachment
interface.
[0009] In one example, the first and second attachment interfaces
are provided by deforming the first and second shield ends around
at least a portion of a perimeter of the first and second end caps.
In another example, at least one retaining member is used to
provide the first and second attachment interfaces. The retaining
member could be a single clip, multiple clips, or a retaining ring
that directly secures the first and second heat shield ends to the
first and second end caps.
[0010] In one embodiment, the heat shield includes a plurality of
convolutes that are spaced apart from each other along a length of
the heat shield. Each convolute is formed as an accordion-like
protrusion extending outwardly from an upper surface of the heat
shield. The plurality of convolutes dissipates stress that would be
generated at the first and second attachment interfaces as the
muffler assembly heats up and cools down.
[0011] In another embodiment, the heat shield is made from a first
component and a second component attached to the first component
via an adjustable attachment interface. The adjustable attachment
interface allows an overall length of the heat shield to be
adjusted to any one of a plurality of overall lengths within a
predetermined range of overall lengths. The adjustable attachment
interface includes at least one longitudinal slot formed in at
least one of the first or second components and at least one
fastener received within the longitudinal slot to secure the first
and second components together.
[0012] The subject invention provides an improved method and
apparatus for attaching a heat shield to a muffler assembly. The
improved method and apparatus can accommodate thermal expansion
without degrading attachment interfaces, is more reliable than
prior attachment interfaces, and has improved acoustics over prior
designs. These and other features of the present invention can be
best understood from the following specification and drawings, the
following of which is a brief description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a perspective view of a muffler and heat shield
assembly incorporating the subject invention.
[0014] FIG. 2A is a partial cross-sectional view of one example of
an attachment interface between a heat shield and a muffler.
[0015] FIG. 2B is an end view of another example of an attachment
interface between a heat shield and a muffler.
[0016] FIG. 3 is a partial cross-sectional view of another example
of an attachment interface between a heat shield and a muffler.
[0017] FIG. 4A is a partial cross-sectional view of another example
of an attachment interface between a heat shield and a muffler.
[0018] FIG. 4B is an enlarged partial cross-section showing a
portion of the attachment interface of FIG. 4A.
[0019] FIG. 4C is an end view of the attachment interface of FIG.
4A.
[0020] FIG. 5 is a side view of an example of a heat shield
including convolutes.
[0021] FIG. 6 is a side view of an example of an adjustable length
heat shield assembly.
[0022] FIG. 7 is an enlarged detail view of circled portion 7 shown
in FIG. 6.
[0023] FIG. 8 is a top view of the detail of FIG. 7.
[0024] FIG. 9 is a side view of a washer used in the attachment
shown in FIG. 6.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0025] A muffler 10, shown in FIG. 1, includes an outer shell 12, a
first end cap 14 mounted to one end of the outer shell 12, and a
second end cap 16 mounted to an opposite end of the outer shell 12.
The first 14 and second 16 end caps are attached to the outer shell
12 by using a spin process. This spin process is well-known in the
art and will not be discussed in detail.
[0026] A heat shield 18 is mounted to the muffler 10 to reduce
adverse effects of heat generated by the muffler 10. The heat
shield 18 has a first shield end 20 mounted to the first end cap 14
at a first attachment interface and a second shield end 22 mounted
to the second end cap 16 at a second attachment interface. The heat
shield 18 extends along an upper length of the outer shell 12 and
is to be positioned between the muffler 10 and a vehicle structure,
such as a floor (not shown).
[0027] The heat shield 18 can be attached to the first 14 and
second 16 end caps in many different manners to define the first
and second attachment interfaces. In one example, at least one
retaining clip 24 is used to secure each of the first 20 and second
22 shield ends to the respective first 14 and second 16 end caps. A
detail of the retaining clip 24 is shown in FIG. 2A for attaching
the first shield end 20 to the first end cap 14. It should be
understood that the second shield end 22 would be attached to the
second end cap 16 in a similar manner.
[0028] As shown in FIG. 2A, the outer shell 12 includes an outer
end 28 and the first end cap 14 includes an outer peripheral edge
30. The spin process aligns the outer end 28 and outer peripheral
edge 30 and spins or folds the outer peripheral edge 30 over the
outer end 28 to form a muffler end cap spin attachment, shown
generally at 32. The first shield end 20 is positioned over the
muffler end cap spin attachment 32 and the retaining clip 24 is
used to secure the heat shield 18 to the first end cap 14.
[0029] In this attachment configuration, the first shield end 20
directly engages an end cap portion adjacent the outer peripheral
edge 30. The retaining clip 24 has a first portion 36 that directly
engages the first shield end 20 and a second portion 38 that
directly engages an external surface 40 of the first end cap
14.
[0030] A single retaining clip can be used to secure the heat
shield 18 to the muffler 10 or a plurality of retaining clips 24,
as shown in FIG. 2B, can be used to secure the heat shield 18 to
the muffler 10. The first shield end 20 is attached to the first
end cap 14 preferably only along an upper portion of the first end
cap 14. The single retaining clip 24 can be positioned anywhere
along the upper portion. Optionally, the single retaining clip 24
could be configured to extend continuously along the upper
portion.
[0031] In the attachment configuration shown in FIG. 2B, each
retaining clip 24 is spaced apart from an adjacent retaining clip
24 along the upper portion. The number of retaining clips 24 needed
may vary depending upon muffler size, vehicle application, or other
known characteristics.
[0032] As shown in FIG. 2A, the heat shield includes a body portion
42 that is spaced apart from an external surface 44 of the outer
shell 12 to define a gap 46. The gap 46 allows the body portion 42
to flex or move to accommodate thermal expansion as the muffler 10
heats up and cools down. The heat shield 18 is shown in a thermally
expanded position in FIG. 2A. An example of a heat shield position
at a cooler temperature is shown by dashed lines at 48. During
thermal expansion, a small amount of relative movement occurs
between the first shield end 20 and the first end cap 14. The
retaining clip 24 allows sufficient movement to accommodate thermal
expansion but prohibits separation of the heat shield 18 from the
muffler. The invention also prohibits any rattling noise.
[0033] The retaining clip 24 can be formed from a resilient spring
material that is snapped over the first end cap 14. The retaining
clip 24 could also be deformed over the muffler end cap spin
attachment 32 with tack welds being used if needed. An example of a
tack weld location is shown at 50. The retaining clip 24 could also
be staked in place using a manual or automated process. Optionally,
the first end cap 14 could include a retention feature 52 that
cooperates with the retaining clip 24 to provide a more secure
attachment interface as needed.
[0034] Another attachment interface 54 for attaching the first
shield end 20 to the first end cap 14 is shown in FIG. 3. It should
be understood that the second shield end 22 would be attached to
the second end cap 16 in a similar manner. This attachment
interface 54 includes deforming the first shield end 20 around the
muffler end cap spin attachment 32. The first shield end 20 is thus
mechanically locked in place by forming or crimping the first
shield end 20 over the muffler end cap spin attachment 32. Staking
operations could also be performed after attachment to provide a
more secure attachment as needed. One benefit with this
configuration is that additional hardware, such as clips, is
eliminated.
[0035] Another attachment interface 60 for attaching the first
shield end 20 to the first end cap 14 is shown in FIGS. 4A-4C. It
should be understood that the second shield end 22 would be
attached to the second end cap 16 in a similar manner. This
attachment interface 60 includes the use of a retaining ring 62
that is snapped over, formed over, or crimped over the first shield
end 20 and the muffler end cap spin attachment 32.
[0036] As shown in FIG. 4A, the heat shield 18 only covers an upper
portion of the outer shell 12. In this attachment configuration,
the retaining ring 62 is installed over the entire perimeter of the
first end cap 14. As shown in FIG. 4B, the retaining ring 62
includes a first portion 64 that directly engages the first shield
end 20 and a second portion 66 that directly engages the external
surface 40 of the first end cap 14. Crimping or staking, as
indicated at 68 in FIG. 4C, could also be used as needed. The
retaining ring 62 can be formed from resilient spring steel or
other similar material.
[0037] As discussed above, the heat shield 18 can be attached to
the first 14 and second 16 end caps in many different manners to
define the first and second attachment interfaces. FIGS. 2A-2B, 3,
and 4A-4C show different examples of these attachment interfaces.
It should be understood that similar attachments could be used for
both the first and second attachment interfaces, or different
attachments could be used for each of the first and second
attachment interfaces. Further, each attachment interface could be
used with different types of heat shields.
[0038] One example of a heat shield is shown generally at 70 in
FIG. 5. In this configuration, the heat shield includes a
longitudinally extending body 72 that is attached to the first 14
and second 16 end caps by any of the attachment methods described
above. The longitudinally extending body includes a plurality of
convolutes 76 that extend outwardly, away from the outer shell 12.
The convolutes 76 are positioned transverse to a longitudinal axis
L defined by the longitudinally extending body 72. The convolutes
76 allow the heat shield 70 to flex in a manner similar to movement
of an accordion. This flexing movement occurs as the muffler 10
heats up and cools down. This movement dissipates stress that would
otherwise attempt to degrade heat shield/end cap attachment
interfaces.
[0039] Another example of a heat shield 80 is shown in FIG. 6. In
this example, the heat shield 80 includes a first portion 82 and a
second portion 84 that is attached to the first portion 82 via an
adjustable attachment interface 100. The adjustable attachment
interface 100 allows the overall length of the heat shield 80 to be
adjusted between a plurality of overall lengths within a
predetermined range of overall lengths.
[0040] In the example shown, the first 82 and second 84 portions
overlap and are connected with a series of Belleville washers 86
and fasteners, such as rivets 88. At least one of the first 82 and
second 84 portions includes a series of slots 90 that receive the
rivets 88. Strengthening ribs 92 are formed on the first 82 and
second 84 portions. The strengthening ribs 92 extend generally
parallel to a longitudinal axis L defined by the heat shield
80.
[0041] An example of a rivet 88 being received within a slot 90 is
shown in FIG. 7. The Belleville washer 86 is positioned on an
external surface 94 of the first 82 or second 84 portion depending
on which of the first 82 or second 84 portions is overlaid on top
of the other of the first 82 or second 84 portions. The rivet 88
and Belleville washer 86 can be moved linearly back and forth
within the slot 90 (see FIG. 8) to adjust the overall length. The
Belleville washer 86 includes turned up edges 96 (see FIG. 9) to
prevent the Belleville washer 86 from digging into the heat shield
80.
[0042] The linear movement allows adjustment of the heat shield 80
prior to attaching the heat shield 80 to the first 14 and second
end caps 16 as described above. This allows a common heat shield
assembly to be used for mufflers 10 of different lengths within a
predetermined range. Also, mufflers of even greater or lesser
lengths than the predetermined range could also benefit from this
type of heat shield 80 as only one of the first 82 or second 84
portions would have to be changed to accommodate the variable
length.
[0043] Further, the linear movement of the rivet 88 within the slot
90 can occur during vehicle operation. This allows for the
difference in thermal expansion between the muffler 10 and the heat
shield 80 generated during normal thermal cycling. This helps to
dissipate stress that would otherwise attempt to degrade heat
shield/end cap attachment interfaces. The Belleville washers 86
keep tension on the adjustable attachment interface 100, which
allows this relative movement without having looseness or
rattling.
[0044] Although a preferred embodiment of this invention has been
disclosed, a worker of ordinary skill in this art would recognize
that certain modifications would come within the scope of this
invention. For that reason, the following claims should be studied
to determine the true scope and content of this invention.
* * * * *