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Publication numberUS3680660 A
Publication typeGrant
Publication dateAug 1, 1972
Filing dateJul 27, 1970
Priority dateJul 27, 1970
Publication numberUS 3680660 A, US 3680660A, US-A-3680660, US3680660 A, US3680660A
InventorsDubois Bert
Original AssigneeTenneco Inc
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Multi-louvered roughness silencer
US 3680660 A
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.
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Description  (OCR text may contain errors)

United States Patent DuBois I [54] MULTI-LOUVERED ROUGHNESS SILENCER.

[72] Inventor: Bert DuBols, Brooklyn, Mich.

[73] Assignee: Tenneco Inc., Racine, Wis.

[22] Filed: July 27, 1970 [21] App]. No.: 58,393

[52] US. Cl. ..181/48, 181/55, 181/61, l8l/63 [51] Int. Cl. ..F01n l/08, F01n 7/18 [58] Field of Search ..181/48, 53-55,

[56] References Cited UNITED STATES PATENTS 2,038,309 4/1936 Oldberg ..1s1/s4 [15] 3,680,660 [4 1 Aug. 1, 1972 3,485,319 12/1969 Balluff ..181/54 FOREIGN PATENTS OR APPLICATIONS 17,680 1905 Great Britain ..181/55 822,559 9/1937 France ..181/55 803,452 4/1951 Germany ..181/55 582,946 10/1958 Italy ..181/55 Primary Examiner-Robert S. Ward, Jr. Attorney-Harness, Dickey and Pierce [57] 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.

5 Claim, 2 Drawing Figures 1 MULTI-LOUVERED ROUGHNESS SILENCER 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 efiect 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 22 of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION The mufiler 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 bushingsS 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 arctacked 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 l7 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 mufller 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 l is principally effective on high $2 i ififillwnfi fi s ffi 'hi h 'ilfl lower frequency range giving the deep power sound favored by sports car drivers. However, by placing the mufiler 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.

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 mufiler, 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 mufiler 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 mufiler 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 subchambers 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.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2038309 *Jul 25, 1934Apr 21, 1936Oldberg SidneySilencer
US3485319 *Dec 21, 1967Dec 23, 1969Walker Mfg CoExhaust gas converter or muffler tube with staggered louvers
DE803452C *Nov 22, 1949Apr 2, 1951Eberspaecher JSchalldaempfer fuer pulsierende Stroemungen mit im Daempferinnern teilweise oder voellig durchgehendem perforiertem Abgasrohr
FR822559A * Title not available
GB190517680A * Title not available
IT582946A * Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3765506 *Nov 8, 1972Oct 16, 1973Tenneco IncSound attenuating muffler
US6695094 *Feb 2, 2001Feb 24, 2004The Boeing CompanyAcoustic muffler for turbine engine
US7267297Sep 2, 2004Sep 11, 2007The Boeing CompanyIntegrated axially varying engine muffler, and associated methods and systems
US7344107Oct 26, 2004Mar 18, 2008The Boeing CompanyDual flow APU inlet and associated systems and methods
US7364116Sep 27, 2004Apr 29, 2008The Boeing CompanyAutomatic control systems for aircraft auxiliary power units, and associated methods
US7513119Feb 3, 2005Apr 7, 2009The Boeing CompanySystems and methods for starting aircraft engines
US7611093Jul 27, 2007Nov 3, 2009The Boeing CompanyDual flow APU inlet and associated systems and methods
US7765784Sep 25, 2006Aug 3, 2010The Boeing CompanyThermally compliant APU exhaust duct arrangements and associated systems and methods
US7798286 *Jul 9, 2008Sep 21, 2010Tmg Performance Products, LlcExhaust muffler having a horizontally extending sound attenuation chamber
US7854297 *Apr 23, 2007Dec 21, 2010The United States Of America As Represented By The Secretary Of The ArmyMuffler and related systems
US7891605Mar 13, 2008Feb 22, 2011The Boeing CompanyAutomatic control systems for aircraft auxiliary power units, and associated methods
US7942239Mar 1, 2010May 17, 2011Tmg Performance Products, LlcExhaust muffler
US8061650Feb 4, 2011Nov 22, 2011The Boeing CompanyAutomatic control systems for aircraft auxiliary power units, and associated methods
US8657227Sep 11, 2009Feb 25, 2014The Boeing CompanyIndependent power generation in aircraft
WO2007134865A1 *May 24, 2007Nov 29, 2007Arvinmeritor Emissions TechHousing for a component of an exhaust system and such a component
Classifications
U.S. Classification181/250
International ClassificationF01N1/00
Cooperative ClassificationF01N1/003
European ClassificationF01N1/00B