U.S. patent number 3,680,660 [Application Number 05/058,393] was granted by the patent office on 1972-08-01 for multi-louvered roughness silencer.
This patent grant is currently assigned to Tenneco Inc.. Invention is credited to Bert DuBois.
United States Patent |
3,680,660 |
DuBois |
August 1, 1972 |
MULTI-LOUVERED ROUGHNESS SILENCER
Abstract
A muffler has a plurality of perforated tubes telescoped over a
perforated gas flow tube to provide a series of expansion chambers
connected in parallel with the gas flow path.
Inventors: |
DuBois; Bert (Brooklyn,
MI) |
Assignee: |
Tenneco Inc. (Racine,
WI)
|
Family
ID: |
22016551 |
Appl.
No.: |
05/058,393 |
Filed: |
July 27, 1970 |
Current U.S.
Class: |
181/250 |
Current CPC
Class: |
F01N
1/003 (20130101) |
Current International
Class: |
F01N
1/00 (20060101); F01n 001/08 (); F01n 007/18 () |
Field of
Search: |
;181/48,53-55,59,63,68-70,61,62 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
17,680 |
|
1905 |
|
GB |
|
822,559 |
|
Sep 1937 |
|
FR |
|
803,452 |
|
Apr 1951 |
|
DT |
|
582,946 |
|
Oct 1958 |
|
IT |
|
Primary Examiner: Ward, Jr.; Robert S.
Claims
I claim:
1. A muffler comprising an imperforate outer housing having an
inlet at one end and an outlet at the other end, a perforated
straight-through gas flow tube in the housing connecting the inlet
and outlet and defining a straight-through gas flow path for the
muffler, said shell defining a chamber around said tube, and a
plurality of radially separated perforated secondary tubes
surrounding said flow tube and subdividing said chamber into
radially separated sub-chambers, said sub-chambers being in radial
communication by means of the perforations in the tubes with gas
flowing through the flow tube, said secondary tubes being spaced
from at least one end of the chamber to define an end chamber, and
sub-chambers communicating with said end chamber.
2. A muffler comprising an imperforate outer housing having an
inlet at one end and an outlet at the other end, a perforated
straight-through gas flow tube in the housing connecting the inlet
and outlet and defining a straight-through gas flow path for the
muffler, said shell defining a chamber around said tube, and a
plurality of radially separated perforated secondary tubes
surrounding said flow tube and subdividing said chamber into
radially separated sub-chambers, said sub-chambers being in radial
communication by means of the perforations in the tubes with gas
flowing through the flow tube, said inlet and outlet and said flow
tube being offset from the center line of the housing and the
smaller of said secondary tubes being substantially concentric with
the flow tube.
3. A muffler as set forth in claim 2 wherein said secondary tubes
are substantially tangent to each other and to the housing.
4. A muffler as set forth in claim 3 wherein the perforate areas in
the tubes are substantially aligned radially and extend angularly
over substantially less than the entire circumferences of the tubes
whereby portions of the sub-chambers are dead.
5. A muffler comprising an imperforate outer housing having an
inlet at one end and an outlet at the outer end, a perforated
straight-through gas flow tube in the housing connecting the inlet
and outlet and defining a straight-through gas flow path for the
muffler, said shell defining a chamber around said tube, and a
plurality of radially separated perforated secondary tubes
surrounding said flow tube and subdividing said chamber into
radially separated sub-chambers, said sub-chambers being in radial
communication by means of the perforations in the tubes with gas
flowing through the flow tube, each of said tubes having a
perforate area that extends over substantially less than the entire
circumference of the tube.
Description
BRIEF SUMMARY OF THE INVENTION
It is the purpose of this invention to provide a low backpressure
muffler containing silencing structure that provides an acoustic
effect similar to a mass of glass fibers or the like, that is, it
attenuates high frequencies and roughness and medium frequencies
while allowing the power sound of the lower frequencies to remain
audible.
The invention accomplishes this by means of expansion chambers
arranged in parallel with the gas flow tube that are provided with
perforated walls to permit gas flow from the tube to the various
chambers.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a longitudinal cross section through a muffler embodying
the invention; and
FIG. 2 is a cross section along the line 2--2 of FIG. 1.
DETAILED DESCRIPTION OF THE INVENTION
The muffler 1 has a housing 3 which has the ends swaged or
otherwise reduced in diameter to provide an inlet bushing 5 and an
outlet bushing 7. The bushings 5 and 7 are aligned and preferably
offset from the axis of the housing 3, the latter being preferably
circular as seen in FIG. 2. A straight-through gas flow tube 9 is
supported in the bushings 5 and 7 and conducts gas from the exhaust
pipe 11 straight through the chamber 10 defined by housing 3 to the
tailpipe 13, the pipes 11 and 13 being telescoped over opposite
ends of the tube 9.
Surrounding the flow tube 9 and tangential to each other and to the
casing 3 along the line 15 are secondary tubes in the form of inner
and outer tubular shells 17 and 19. The shells are preferably spot
welded or arc-tacked to the housing 3 along the line of tangency.
The halves of the tube 9 and the shells 17 and 19 which face away
from their line of tangency with the shell are provided along most
of the lengths with perforations that are preferably louvers 21
which arranged to direct the gas in a circular pattern as indicated
in FIG 2. The flow tube 9 and the surrounding shells divide the
interior 10 of the casing 3 into sub-chambers 23, 25 and 27. The
shells 17 and 19 are preferably spaced slightly from the opposite
ends of the housing 3 to provide end chambers 29 and 31 which
communicate with the previously mentioned chambers.
In operation, gas flowing through the muffler 1 can pass from the
exhaust pipe 11 to tailpipe 13 with a minimum of horsepower loss
because of the low backpressure created by the straight-through
flow path of tube 9. Pressure pulses in the gas as it passes
through the tube can expand radially or sideways and pass, in
series, into the chambers 23, 25 and 27 after passing through
louvers 21. The gas can also expand longitudinally into the end
chambers 29 and 31. Since the louver patches are radially aligned
and extend over substantially less than all the circumferences of
the tube 9 and shells 17 and 19, the non-louver subtended portions
of chambers 23, 25 and 27 are partially "dead" (no flow through)
and act in a special way to absorb acoustic energy.
The muffler 1 is principally effective on high frequencies and
roughness and on medium frequencies so that the audible sound
passed by the muffler is in the lower frequency range giving the
deep power sound favored by sports car drivers. However, by placing
the muffler 1 in an exhaust system so that the maximum pressure
point or anti-node of a troublesome frequency falls centrally
within the perforated region of the tube 9, attenuation of such
lower frequency can be achieved to a substantial degree.
Modifications may be made without departing from the spirit and
scope of the invention.
* * * * *