U.S. patent application number 10/965512 was filed with the patent office on 2006-04-20 for exhaust silencer with acoustic damping mat.
Invention is credited to Trent Lee Nentrup.
Application Number | 20060081416 10/965512 |
Document ID | / |
Family ID | 36179546 |
Filed Date | 2006-04-20 |
United States Patent
Application |
20060081416 |
Kind Code |
A1 |
Nentrup; Trent Lee |
April 20, 2006 |
Exhaust silencer with acoustic damping mat
Abstract
An exhaust silencer includes an upper shell and a lower shell
attached to the upper shell to define an internal cavity. Acoustic
damping material is positioned within said internal cavity to
reduce radiated and transmitted noise. A plurality of retention
members compresses the acoustic damping material against an inner
surface of the upper shell. The acoustic damping material is only
located in the upper shell and thus is not affected by condensate
that collects in the lower shell.
Inventors: |
Nentrup; Trent Lee; (Hope,
IN) |
Correspondence
Address: |
CARLSON, GASKEY & OLDS, P.C.
400 WEST MAPLE ROAD
SUITE 350
BIRMINGHAM
MI
48009
US
|
Family ID: |
36179546 |
Appl. No.: |
10/965512 |
Filed: |
October 14, 2004 |
Current U.S.
Class: |
181/256 ;
181/222; 181/227; 181/252 |
Current CPC
Class: |
F01N 2310/02 20130101;
F01N 13/1888 20130101; F01N 1/24 20130101 |
Class at
Publication: |
181/256 ;
181/252; 181/222; 181/227 |
International
Class: |
F01N 1/24 20060101
F01N001/24; F01N 1/10 20060101 F01N001/10; F01N 7/08 20060101
F01N007/08 |
Claims
1. An exhaust silencer comprising: an upper shell; a lower shell
attached to said upper shell to define an internal cavity; and
acoustic damping material held within said internal cavity against
said upper shell.
2. The exhaust silencer according to claim 1 wherein said acoustic
damping material is compressed against an inner surface of said
upper shell.
3. The exhaust silencer according to claim 2 wherein said acoustic
damping material comprises a mat having a first surface
substantially engaging said inner surface and a second surface
facing said internal cavity.
4. The exhaust silencer according to claim 3 including at least one
compression member in engagement with said second surface to
generate a retaining force for holding said mat against said upper
shell.
5. The exhaust silencer according to claim 4 wherein said at least
one compression member comprises a plurality of straps.
6. The exhaust silencer according to claim 5 wherein each of said
plurality of straps has a pair of strap ends interconnected by a
center portion wherein said center portion engages said mat with
each of said pair of strap ends being directly attached to said
upper shell.
7. The exhaust silencer according to claim 3 wherein said inner
surface of said upper shell has a first portion and a second
portion wherein said first portion is uncovered and said second
portion is covered with said mat.
8. The exhaust silencer according to claim 1 wherein said acoustic
damping material is only located in said upper shell.
9. The exhaust silencer according to claim 8 including an inlet to
be in communication with a first exhaust system component and an
outlet to be in communication with a second exhaust system
component wherein said acoustic damping material reduces radiated
and transmitted noise as exhaust air moves through said internal
cavity from said inlet to said outlet.
10. The exhaust silencer according to claim 8 wherein said acoustic
damping material includes fiberglass material.
11. An exhaust silencer comprising: an upper shell; a lower shell
attached to said upper shell to define an internal cavity; acoustic
damping material positioned within said internal cavity; and a
plurality of retention members compressing said acoustic damping
material against an inner surface of said upper shell.
12. The exhaust silencer according to claim 11 wherein said lower
shell provides an uncovered inner surface spaced apart from said
acoustic damping material.
13. The exhaust silencer according to claim 11 wherein said
acoustic damping material is only located in said upper shell.
14. The exhaust silencer according to claim 13 wherein said
plurality of retention members comprises a plurality of straps with
each of said plurality of straps having a center portion
interconnecting a pair of strap ends, said center portion engaging
said acoustic damping material with each of said pair of strap ends
being directly attached to said upper shell.
15. The exhaust silencer according to claim 14 wherein each end of
said pair of strap ends is welded to said upper shell.
16. The exhaust silencer according to claim 14 wherein said upper
shell includes an upper wall and a pair of vertical side walls
extending from opposing edges of said upper wall and wherein said
plurality of straps includes a first strap fixed to one of said
pair of vertical side walls, a second strap fixed to another of
said pair of vertical side walls, a third strap fixed to said upper
wall adjacent one of said opposing edges, and a fourth strap fixed
to said upper wall adjacent another of said opposing edges.
17. The exhaust silencer according to claim 14 wherein said
acoustic damping material comprises a mat that covers one portion
of said inner surface of said upper shell while leaving a second
portion of said inner surface of said upper shell uncovered.
18. The exhaust silencer according to claim 17 wherein said mat is
formed from a fiberglass material, and said plurality of straps and
said upper shell are formed from a stainless steel material.
Description
TECHNICAL FIELD
[0001] The subject invention relates to an exhaust silencer that
includes acoustic damping material to reduce noise.
BACKGROUND OF THE INVENTION
[0002] An exhaust silencer includes an upper shell and a lower
shell that together define an internal cavity. Baffle holes and
extrusions are formed within the internal cavity. Exhaust air flows
from an inlet, through the baffle holes and extrusions, and out an
outlet. The baffle holes and extrusions define an exhaust flow path
and cooperate to reduce noise as exhaust air flows through the
exhaust silencer.
[0003] Some disadvantages with this traditional exhaust silencer
configuration are mid-frequency noise attenuation capability and
shell resonance noise. One solution that has been used to address
these noise issues has been to provide an exhaust silencer that is
loosely filled with acoustic damping material. This solution has
provided unsatisfactory results. In this configuration, loose fill
falls into the exhaust flow path, which can increase back-pressure.
Further, the loose fill settles into the lower shell where
condensate typically collects. Thus, the loose fill soaks up the
condensate, which can degrade the loose fill and also can prevent
the condensate from draining out of the lower shell as needed.
[0004] Thus, there is a need for an exhaust silencer that can
reduce radiated as well as transmitted noise without increasing
back pressure and adversely affecting operation of the exhaust
silencer.
SUMMARY OF THE INVENTION
[0005] An exhaust silencer includes an upper shell and a lower
shell attached to the upper shell to define an internal cavity.
Acoustic damping material is compressed against an inner surface of
the upper shell to reduce radiated and transmitted noise. The
acoustic damping material is only located in the upper shell and
thus is not affected by condensate that collects within the lower
shell during vehicle operation.
[0006] The exhaust silencer includes at least one retention member
that provides and maintains a compression force against the
acoustic damping material. In one example, the at least one
retention member includes a plurality of straps. Each of the
plurality of straps has a center portion that extends between first
and second strap ends. The center portion engages and compresses
the acoustic damping material against the upper shell, with the
first and second strap ends directly mounted to the upper
shell.
[0007] Locating the acoustic damping material only in the upper
shell keeps the acoustic damping material dry and avoids placing
the acoustic damping material in an exhaust flow path through the
exhaust silencer. Also, shell resonance for both the upper and
lower shells is improved. 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
[0008] FIG. 1 is an assembled perspective view of an exhaust
silencer incorporating the subject invention.
[0009] FIG. 2 is side cross-sectional view of the exhaust silencer
of FIG. 1.
[0010] FIG. 3 is an end cross-sectional view of the exhaust
silencer of FIG. 2.
[0011] FIG. 4 is a perspective view of one example of a side
retention member.
[0012] FIG. 5 is a perspective view of one example of a bottom
retention member.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0013] An exhaust silencer 10 is shown in FIG. 1 and includes in
inlet 12 and an outlet 14. The inlet 12 is in communication with an
upstream exhaust system component and the outlet 14 is in
communication with a downstream exhaust system component as
known.
[0014] The exhaust silencer 10 includes an upper shell 16 that is
attached to a lower shell 18 to define an internal cavity 20, see
FIG. 2. Baffle holes and extrusions are located within the internal
cavity 20 as known, but are not shown for reasons of clarity.
Exhaust air flows along a flow path extending from the inlet 12,
through the baffle holes and extrusions, and out the outlet 14.
[0015] Acoustic damping material 22 is pressed against an inner
surface 24 of the upper shell 16. The acoustic damping material 22
reduces transmitted noise generated by exhaust flow and reduces
radiated noise generated by resonance of the upper 16 and lower 18
shells.
[0016] In the example shown in FIG. 2, the acoustic damping
material 22 is formed as a mat 26 that covers a first portion 30 of
the inner surface 24 of the upper shell 16. A second portion 32 of
the inner surface 24 of the upper shell 16 remains uncovered, i.e.
the second portion 32 is not covered by acoustic damping material
22. The amount of coverage of the first portion 30 relative to the
second portion 32 can vary depending upon vehicle application,
size, and/or other known specifications. A smaller mat portion,
when maintained in compression against the upper shell 16, can act
as a mute for both the upper 16 and lower 18 shell. A larger mat
portion additionally increases attenuation of high frequency aural
content by diffusing, absorbing, and scattering short-length sound
waves.
[0017] The mat 26 is only located within the upper shell 16. By
physically locating the mat 26 only in the upper shell 16, the
acoustic damping material 22 is kept dry. This allows condensate,
which typically collects in the lower shell 18 to be properly
drained from the lower shell. Further, by pressing the mat 26
against the inner surface 24 of the upper shell 16, the acoustic
damping material 22 is not located in the flow path of the exhaust
air.
[0018] At least one retention member 40 is used to provide and
maintain a compression force against the mat 26. In one example,
shown in FIGS. 2 and 3, the at least one retention member 40
comprises a plurality of retention members 40. In the example
shown, each retention member 40 is a strap having a center portion
42 that extends between first 44 and second 46 strap ends. The
center portion 42 compresses the mat 26 against the inner surface
24 of the upper shell 16. The first 44 and second 46 strap ends
extend beyond the mat 26 and are directly attached to the upper
shell 16. The first 44 and second 46 strap ends are preferably
puddle welded to the upper shell 16, however, other attachment
methods could also be used.
[0019] As shown in FIG. 3, the upper shell 16 includes an upper
wall 50 and a pair of vertical side walls 52 extending from
opposing edges of the upper wall 50. In one configuration, the
plurality of retention members 40 includes a first strap 54 fixed
to one of the pair of vertical side walls 52 and a second strap 56
fixed to another of the pair of vertical side walls 52. A third
strap 58 is fixed to the upper wall 50 adjacent one of the opposing
edges and a fourth strap 60 is fixed to the upper wall 50 adjacent
another of the opposing edges. The first 54, second 56, third 58,
and fourth 60 straps cooperate to securely hold and maintain the
mat 26 in compression against the upper shell 16.
[0020] FIG. 4 shows one example of a strap configuration that could
be used for either the first 54 or second 56 strap. This strap
configuration provides a strap body 62 with transversely extending
first 64 and second 66 strap ends. The strap body 62 includes rib
portions 68 that generally correspond in shape to ribs 70 formed on
the upper shell 16 (see FIG. 1). The mat 26 is compressed between
one vertical side wall 52 and the strap body 62 and the first 64
and second 66 strap ends are attached to the upper shell 16 as
described above.
[0021] FIG. 5 shows one example of a strap configuration that could
be used for either the third 58 or fourth 60 strap. This strap
configuration provides a strap body 72 with transversely extending
first 74 and second 76 strap ends. The strap body 72 is curved to
match a curved profile 78 of the upper shell 16 (see FIG. 1). The
strap body 72 includes rib portions 80 that generally correspond in
shape to the ribs 70 on the upper shell 16. The mat 26 is
compressed between the upper wall 50 and the strap body 72 and the
first 74 and second 76 strap ends are attached to the upper shell
16 as described above.
[0022] Any type of acoustic damping material 22 known in the art
can be used to form the mat 26. In one example, an E-glass silentex
powertex material manufactured by BGF Industries is used to form
the mat, however, other fiberglass materials, or other materials,
could also be used. Additionally, the upper 16 and lower 18 shells,
and the straps shown in FIGS. 4 and 5 are preferably made from 409
stainless steel, however, other known materials could also be
used.
[0023] It should be understood that straps are just one example of
a retention member that could be used to compress the mat 26
against the upper shell 16. Bands, baffles, netting or an inner
shell portion could also be used to hold the mat 26 in place.
[0024] As discussed above, the subject invention provides an
exhaust silencer 10 with improved acoustic damping. Locating the
acoustic damping material 22 only in the upper shell 16 keeps the
acoustic damping material 22 dry and avoids placing the acoustic
damping material 22 in an exhaust flow path through the exhaust
silencer 10. Also, shell resonance for both the upper 16 and lower
18 shells is improved.
[0025] 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.
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