US2543461A - Muffler with plural side branch chambers - Google Patents

Description

Feb. 27, 1951 E. D. LATULlPFE MUFFLER WITH PLURAL SIDE BRANCH CHAMBERS Filed July 20, 1949 2 Sheets-Sheet l 500 ZZLAruL/PPA' BY 1/(w m w jwwwwmw Feb. 27, 1951 E. D. LATULIPPE MUFFLER wrm PLURAL SIDE BRANCH CHAMBERS Filed July 20. 1949 2 Sheets-Sheet 2 INVEN'I'OR. 00) fl. Z A 704 IPPE BY aL Patented Feb. 27, 1951 MUFFLER WITH PLUR-AL SIDE BRANCH CHAMBERS Eddy D. Latulippe, Englewood, N. J., assignor to Acre-Sonic Corp., New York, N. Y., a corporation of New York Application July 20, 1949, Serial No. 105,686

9 Claims.

This invention relates to exhaust mufiiers of the type disclosed by the E. D. Latulippe Patent No. 2,158,030 issued May 9, 1939. This type may be used to muffle any exhaust creating an acoustical disturbance. It is particularly adapted for application to aircraft having engines producing exhausts which it is desirable to muilie to make their characteristic noise less disturbing. This type may be produced in a light-weight form producing relatively littleback pressure while effectively muffling.

One of the objects of the present invention is to improve on this type of muffler to produce a light-weight muffler that muffles even more effectively with even less back pressure. When back pressure is exerted against an exhaust from an engine the engine cannot operate at its maximum power. It is undesirable to decrease the maximum power of an aircraft engine. Another object is to improve on this type of muiiler to produce a mullier that may be more easily manufactured and which is constructed so its parts are less likely to shake loose during the heavy vibration and generally severe service conditions encountered in aircraft applications. Other objects may be inferred from the following.

A specific example of a muffler constructed in accordance-with the present invention is illustrated by the accompanying drawings. and described hereinbelow for the purpose of disclosing the principles and operation of this invention. No unusual manufacturing problems are involved and anyone skilled in the art who knows the principles and operation of the invention may construct this exemplary muffler. Such familiarity will permit changes in the specific details shown and will enablethe production of various modifications. One suggestive modification is illustrated. by the drawings and described herein.

In these drawings Fig. 1 is a side elevation of the mufiler;

Fig. 2 is a longitudinal, vertical section with the parts clarified by a scale enlargement which requires the mufiier to be broken because of space Fig. '7 is a view similar to Fig. 2, but is on a relatively enlarged scale and shows the tail piece in modified form;

.Fig. 8 is an end view of Fig. 7, and

Fig; 9 is a vertical transverse cross section taken on the line 99 in Fig. 7.

Referring to Fig. l the mufiler has an elongated outer casing in the form of a cylindrical tube. The inlet end of this casing I has a tapering" inlet chamber 2, and the outlet end of the casing I has a tapering outlet chamber 3. The exhaust pipe 4 connects with the inlet chamber 2 while as part of the muflier to tail piece 5 extends backwardly and downwardly at an angle from the outlet chamber 3. The exhaust pipe 4 is shown with an air inlet pipe 6 provided with an air funnel I so the movement of the aircraft drives air through the pipe 6 into the exhaust pipe 4 to keep enough air in the exhaust and mufiler system to prevent an explosion hazard in the event the aircraft engine misfires and fills the system with unburnt fuel.

It is to be assumed that the mufiier is applied to an aircraft. The device is long and relatively slender and so has little wind resistance when installed on the outside of the aircraft where it is exposed.

The mufilers internal construction is shown by Fig. 2. In addition to the outer casing I the mullier has an elongated inner casing 8. The outer casing I and the inner casing 8 are mutually spaced and are respectively constructed and mutually arranged to conduct the exhaust between the casings I and 8 and-inside of the inner casing 8. This inner casing 3 is also shown as a cylindrical tube and it is concentrically arranged inside the outer casing I. The casing 8 is of smaller diameter than the casing I so its outside is mutually spaced from the inside of the casing I to provide a tube-likespace extending longitudinally of the muffler. The inside of the inner casing 8 provides another longitudinally extending space.

The outer casing I has superimposed and mutually spaced outer and inner walls. The outer wall Ia is substantially gas-tight and may comprise a sheet metal tube. It joins with the chambers 2 and 3 in a gas-tight manner. The inlet chamber 2 is connected with the exhaust pipe 4 in a gas-tight manner and the tail piece 5 is connected with the outlet chamber 3 in a gastight'manner. All of these parts of the muiiler may be made from sheet metal that is free from openings.

The outer casings inner wall I b is perforated throughout its entire extent. It may comprise a sheet metal wall having sufficient perforations to give it the characteristic of a screen. The ends of this inner wall lb have outwardly projecting annular flanges lc by which it is connected with the outer wall la of this outer casing l.

The inner casing 8 has superimposed and mutually spaced outer and inner perforated walls Ba which are similar to the wall lb of the outer casing. The inner casing also has a central substantially gas-tight wall 8b which is substantially like the outer wall la of the outer casing I. Where reference is here made to walls being substantially alike it is to be understood that different diameters are involved and that the ends are slightly modified in the respective instances. Thus the ends of the perforated walls 8a of the inner casing are joined together at their front ends by inner and outer rings H which have flanges connecting with these walls 8a and which taper inwardly to provide flanges which are interconnected by being fastened to the gas-tight wall 8b which has its end sandwiched between them. At the outlet end of the device the outer one of the perforated walls 8a is tapered inwardly and fastened to the inner one of the walls 8a with the gas-tight central wall 8b butted against the tapering end of the outer perforated wall.

In Fig. 2 the perforated insides of the inner walls of the outer and inner casings respectively are shown perforated only in the cross-sectioned portions. This is done to avoid confusion which results when the holes are shown throughout the curving halves illustrated in elevation. Fig. l is provided to clarify the construction, and in this the perforations in the walls lb are marked Id and those in the walls 8a of the inner casing are marked 80. All of the perforations ld in the elevation portion of this figure are not shown but a few are indicated to show their distribution. In all cases the perforations are relatively small and there are a relatively large number of them, the walls being completely filled with the perforations in each instance.

As shown particularly well by Fig. 3, the inner casing is positioned inside the outer casing by the use of short channel sections l2 having their webs radially arranged and their flanges fastened to the wall lb and the outer one of the walls 8a respectively. Sufiicient of these channel sections are used to secure rigidly and they are shown only at the ends of the two casings.

Fig. 3 also shows that the various walls are formed by cylindrically bending metal sheets and overlapping and fastening their ends. Butt joints could also be used if the joints are made adequately permanent.

The tail piece 5 of the device is shown in maximum detail by Figs. 2 and 5. This tail piece includes superimposed, gradually flattening tail conduits 5a and 5b which extend backwardly from the chamber 3 in a gas-tight manner as previously explained. Conduit 5b connects with the inside of the inner casing 8 through an inner short casing 3a that extends through the outer casing 3b of the chamber 3 as a short tubular cylinder part having its inner end fastened to the tapering wall of the outer one of the walls 8a of the inner casing. Thus the chamber 3 comprises the outer short casing 3b and the inner short casing 3a. This latter casing 311 is provided with a plurality of partial punches 30 which are formed as inwardly projecting scoops pointing in the direction the exhaust comes from the inner casing. This inner short casing 3a positions the inner end of the conduit 5b within the tail piece and the outer end of the conduit 5b is rigidly positioned therein by a plurality of short channel sections 50. These sections are arranged with their webs transversely between the outer flat end of the outer tail conduit 5a with their flanges fastened to its insides. These sections have slots 5d receiving the flattened end of the inner tail conduit 5b. The parts are assembled in a rigid manner.

The outlet chamber 3 and the tail piece 5 follow the general arrangement of the comparable parts disclosed by the mentioned Latulippe patent. They differ from it in that a larger number of the openings or scoops 3c are used and in that these openings are arranged directly inside of the outlet chamber 3b rather than farther back in the tail piece. The tail piece is also shown angling downwardly because this is generally a better arrangement for many aircraft installations.

As shown in Fig. 2 the spacing between the walls of the respective casings is considerably less than the spacing between the two casings proper. Sound absorbent material lla is positioned between the mutually opposed'surfaces of the gas tight walls and the perforated walls respectively. Thus this sound absorbent material is positioned between the walls la and lb and between the walls 841 and 8b. The absorbent material may comprise stainless steel wool or other refractory fibrous material capable of resisting the vibration. This material is packed relatively compactly between the respective walls. The material should be acoustically absorbent respecting at least the dominant frequencies of the exhausts vibration.

With the muffler connected with the exhaust pipe and with the latter carrying the exhaust creating the disturbing noise the operation of the mufiler is as follows.

The exhaust gases enter the inlet chamber 2 and are thereby connected with both the space between the two casings and the space inside the inner casing. The chamber 2 functions to equalize the pressure between these two spaces. The exhaust travels through both spaces and into the outlet chamber 3 through which it passes to exit through the tail piece 5. This tail piece functions to impede the flow of the exhaust gases from the outlet chamber to provide a very slight back pressure which slightly increases the normal pressure of the exhaust traveling through the casings of the muffler. The openings 3c in the short inner casing 3a of the outlet chamber 3 also interconnect the spaces between the casings and inside the inner casing to assure pressure equalization therebetween. The flattening of the respective tail piece conduits should be adequate to provide this slight back pressure effect, but not sumcient to impede the exhaust so much as to materially affect the power output of the engine producing the exhaust.

Since the pressures in the two spaces provided by the two casings are the same the exhaust gases tend to travel uniformly through both spaces. As the exhaust gases travel through the spaces the exhaust gases are confined by the double walled construction shown and described. The gases tend to penetrate the perforated wall so that the sound absorbent material l2 functions as a sound absorbent wall carrying the exhaust gases. As

a result the acoustical energy is effectively mufiled out by absorption. This is done without abrupt accede- 1 5 changes of theaflow-ing' direction: of i the exhaust ases or' in any otheryway-impeding the exhaust gasesflow-materiallwte result :in high' back pressure;

The -murder: illustrated is. relatively small. In the case of larger mu'fll'ers intendedfor larger engines the-number of multiple-walled casings may be increased to prov-idemore efiective sound absorption from the traveling exhaust gases;

The slight tape-r of the exhaust chamber 312' is insome instances by itself sufficient-to impede the exhaust flowing from the' muffierto asufficient extent to materially increase thesoundabsorption properties; Where-adequatesound absorption is provided in thisfashionthe tail piece 5 may be eliminated.- The tail piecemay also be eliminated in cases where themufii'er is made longer to maintain theexhaust gases in -contact with the sound absorbent material for a longer period of time than-in thecase ofthe shorter muffler illustrated.

Since the exhaust is simply carried straight through the muffler the parts may be'made very light in weight by'using relatively thin-gauged sheet metal suchas thin stainless steel. Any pulsations'inthe exhaust are-rapidly damped out by the sound absorbent material l2 so that the muffler is not subjected to=material vibration due to the exhaust;

In the modification shown by Figs. 7" through 9' a straight cylindricaloutl'et chamber 14 is substituted' for the taperedchamber-Ii' ofthe mufiler assembly shown-by Figs. 1" through 5; This per-'- forms" all the functions-previously described. The various walls of the, inner casingaresomewhat differently arranged but this diiference is relatively slight andneed not be described since-it is apparent from the drawings.

The modified tailpiece I5= has an outer casing shaped somewhat like an' egg-and internally provided with a tear drop shell 16 positioned with its large endpointingtowardstheflow of exhaust gases andwith its outside spacedfrom the inside of the shell [5 by struts ll turned edgewise'to the flowing exhaust-gases. The casing-"and shell correspond generally in contour.

With this modified arrangementthe tear "drop shell I 6 provides a slight flow impedancetobuild upthe'slightback pressure back inthe mainportion of the mufl'ler. directly impinged by the exhaust gases leaving theinner casing-its'general shape is such that it does not have to: provide much reaction to these gases; The shells' shape makes it inherently rigid. Furthermore it isreceiving the exhaust gases after the vibration energyhas been largely removed.by-being absorbed by the sound absorbing material between the multiple; walls of the various casings:

It is to be noted that the construction" is' such that'theexhaust gases cannotienterbetween the various walls of the respective casings l' and'8 through any spaces between their endedges. The effect is substantially that Qf'cOnduQtingthe exhaust gases through a plurality-of straightsound absorbent passageway walls. with the. exhaust uniformly distributed. throughout the various passageways without any localized pressure nonuniformities. The uniform distribution of the pressure throughoutthe entiredeyice not only affects maximum sound. dampening. or. muffling but has the further. adivantagefofj preventing .the formation of localized. hotspots in' the. muffler construction.

The acoustical absorbent. material. permits Althou h the shell IE is r some-penetration by the exhaust; The-acoustical energy'in the absorbed exhaust is reflectedlback and forth between the. respective casing walls and thus: damped out. Thiseflect. is; obtained when the. sound absorbent material is eliminated.

When using the material thetefiect increases the sound, absorption efficiency.

Assshown by Fig. 7 the tail of the tear drop shell [6. is: longv and projectstwell beyond the back end of the outer: casing I5. The outlet end of thecasing [5 has substantially the. same inside diameter. as that of. the inlet chamber 2 of the muffler where it connectswith the exhaust pipe 4. The. contours of the casing l5 and shell IS follow each other as much aspossible with the foregoing qualifications. Thisconstruction producesa jet eiiject providing thrustfor pushing the aircraft.

Iclaim:

1. An exhaust muffler including mutually spaced outer andv inner elongated casings constructed and arranged to conduct the exhaust therethroughbetween said casings and inside said inner casing, said outer casing having superimposed andimutually spaced outer and inner walls with: said outer wall substantially gas-tight and said inner wall perforated, and said inner casing having superimposed and mutually spaced outer and inner perforated: walls anda central substantially gas-tight wall interposed therebetween.

2. An exhaust muii'ler including mutually spaced outer and inner elongated casings con structed and. arranged to conductthe, exhaust therethrough. betweenv said. casings and inside saidlinner casing, said outer casing having superimposedand mutually spaced outer. and inner walls with said outer'wallsubstantially gas-tight and said inner wall perforated, and said inner casing having superimposed and mutually spaced outer and inner perforated walls and a central substantially gas-tightwall interposed therebetween, sound-absorbent material being positioned between the mutually opposed surfaces of said substantially gas-tight walls and said perforated walls respectively.

3.. An exhaust muffler including mutually spaced outer andinner elongated casings. constructed and arranged to. conduct the exhaust therethrough between said casings-and-inside said inner casing, said outer casing havingsuperimposed and mutually spacedouter and-inner walls with said outer wall substantially-gas-tight and said inner wall perforated, and said inner casing having superimposed and mutually space-d outer and innerperforated. walls and a central substantially gas-tightwall interposed therebetween, said casings having an inlet'chamber at their exhaust-inlet endswith the latter and said chamberconstructed and arranged to interconnect'the respectiveinsidesof said casings and to introduce the exhaust thereto, and said casings having an outlet chamber at their exhaust-outlet-ends with the latter andsaid outlet chamber constructed and arrangedto interconnect their respective insidtsandto carry the. exhausttherefrom...

4.. An exhaust muffier including mutually spaced outer andinner elongated casings con structed and arranged to conduct. the exhaust therethrough between said casings and inside inner. casing, said outer casing having superimposed. and: mutually spaced outer and inner. walls with said outer Walls substantially gas-tight and said inner wall perforated, and said inner casing hayingsuperimposed and mutually spaced outer and inner perforated walls and a central substantially gas-tight wall interposed therebetween, said casings having an inlet chamber at their exhaust-inlet ends with the latter and said chamber constructed and arranged to interconnect the respective insides of said casings and to introduce the exhaust thereto, and said casings having an outlet chamber at their exhaust-outlet ends with the latter and said outlet chamber constructed and arranged to interconnect their respective insides and to carry the exhaust therefrom, sound absorbent material being positioned between the mutually opposed surfaces of said substantially gas-tight Walls and said perforated walls respectively.

5. An exhaust muffler including mutually spaced outer and inner elongated casings constructed and arranged to conduct the exhaust therethrough between said casings and inside said inner casing, said outer casing having superimposed and mutually spaced outer and inner walls with said outer Wall substantially gas-tight and said inner wall perforated, and said inner casing having superimposed and mutually spaced outer and inner perforated walls and a central substantially gas-tight wall interposed therebetween, said casings having an inlet chamber at their exhaust-inlet ends with the latter and said chamber constructed and arranged to interconnect the respective insides of said casings and to introduce the exhaust thereto, and said casings having an outlet chamber at their exhaustoutlet ends with the latter and said outlet chamber constructed and arranged to interconnect their respective inside and to carry the exhaust therefrom, said outlet chamber connecting with means for at least slightly impeding the exhaust flow therefrom.

6. An exhaust muffler including mutually spaced outer and inner elongated casings constructed and arranged to conduct the exhaust therethrough between said casings and inside said inner casing, said outer casing having superimposed and mutually spaced outer and inner walls with said outer wall substantially gas-tight and said inner wall perforated, and said inner casing having superimposed and mutually spaced outer and inner perforated walls and a central substantially gas-tight wall interposed therebetween, said casings having an inlet chamber at their exhaust-inlet ends with the latter and said chamber constructed and arranged to interconnect the respective insides of said casings and to introduce the exhaust thereto, and said casings having an outlet chamber at their exhaust-outlet ends with the latter and said outlet chamber constructed and arranged to interconnect their respective insides and to carry the exhaust therefrom, sound absorbent material being positioned between the mutually opposed surfaces of said substantially gas-tight walls and said perforated walls respectively, said outlet chamber connecting with means for at least slightly impeding the exhaust flow therefrom.

'7. An exhaust mufiler including mutually spaced outer and inner elongated casings constructed and arranged to conduct the-exhaust therethrough between said casings and inside said inner casing, said outer casing having superimposed and mutually spaced outer and inner walls with said outer wall substantially gastight and said inner wall perforated, and said inner casing having superimposed and mutually spaced outer and inner perforated walls and a central substantially gas-tight wall interposed therebetween, said casings having an inlet chamber at their exhaust-inlet ends with the latter and said chamber constructed and arranged to interconnect the respective insides of said casings and to introduce the exhaust thereto, and said casings having an outlet chamber at their exhaust-outlet ends with the latter and said outlet chamber constructed and arranged to interconnect their respective insides and to carry the exhaust therefrom, sound absorbent material being positioned betwen the mutually opposed surfaces of said substantially gas-tight walls and said perforated walls respectively, said outlet chamber connecting with means for at least slightly impeding the exhaust flow therefrom, said outlet chamber including a substantially gastight outer short casing extending from said outer elongated casing and an inner short casing having gas ports and positioned inside and spaced from said outer casing and extending from said inner elongated casing. A

8. An exhaust muffler including mutually spaced outer and inner elongated casings constructed and arranged to conduct the exhaust therethrough between said casings and inside said inner casing, said outer casing having superimposed and mutually spaced outer and inner walls with said wall substantially gas-tight and said inner wall perforated, and said inner casing having superimposed and mutually spaced outer and inner perforated walls and a central substantially gas-tight wall interposed therebetween, said casings having an inlet chamber at their exhaust-inlet ends with the latter and said chamber constructed and arranged to interconnect the respective insides of said casings and to introduce the exhaust thereto, and said casings having an outlet chamber at their exhaust-outlet ends with the latter and said outlet chamber constructed and arranged to interconnect their respective insides and to carry the exhaust therefrom, sound absorbent material being positioned between th mutually opposed surfaces of said substantialy gas-tight walls and said perforated walls respectively, said outlet chamber connecting with means for at least slightly impeding the exhaust flow therefrom, said outlet chamber including a substantially gas-tight outer short casing extending from said outer elongated casing and an inner short casing having gas ports and positioned inside and spaced from said outer short casing and extending from said inner elongated casing, said means including superimposed gradually flattening tail conduits respectively extending from said outer and inner short casmgs.

9. An exhaust muffler including mutually spaced outer and inner elongated casings constructed and arranged to conduct the exhaust therethrough betwen said casings and inside said inner casing, said outer casing having superimposed and mutually spaced outer and inner walls with said outer wall substantially gas-tight and said inner wall perforated, and said inner casing having superimposed and mutually spaced outer and inner perforated, Walls and a central substantially gas-tight Wall interposed therebetween, said casings having an inlet chamber at their exhaust-inlet ends with the latter and said chamber constructed and arranged to interconnect the respective insides of said casings and to introduce the exhaust thereto, and said casings having an outlet chamber at their exhaust-outlet ends with the latter and said outlet chamber constructed and arranged to interconnect their respective insides and to carry the ex- 9 haust therefrom, said outlet chamber connecting with means for at least slightly impeding the exhaust flow therefrom, said means including a generally egg-shaped casing with a generally tear drop shaped body mounted therein and spaced therefrom with itsv tail pointing baekwardly and projecting beyond the outlet end of the said egg-shaped casing.

EDDY D. LA'IULIPPE.

REFERENCES CITED Number Number 10 UNITED STATES PATENTS Name Date Gray Apr. 1, 1919 Schnell June 23, 1931 Rauen Feb. 24, 1942 FOREIGN PATENTS Country Date Great Britain Feb. 9, 1937 France June 2, 1939 Certificate of Correction Patent No. 2,543,461 February 27, 1951 EDDY D. LATULIPPE It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 2, line 13, for the Words mulfler to read muyfler a; column 4:, line 23, for in read by; column 8, lines 11 and 59, for betwen read between; line 44:, same column, for substantialy read substantially;

and that the said Letters Patent should be read as corrected above, so that the same may conform to the record of the case in the Patent Oifice.

Signed and sealed this 1st day of May, A. D. 1951.

[SEAL] THOMAS F. MURPHY,

Assistant Commissioner of Patents.

Certificate of Correction Patent No. 2,548,461 February 27, 1951 EDDY D. LATULIPPE It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows Column 2, line 13, for the Words mufiier to read mufiler a; column 4, line 23, for in read by; column 8, lines 11 and 59, for Ioetwen read between; line 44, same column, for substantialy read substantially;

and that the said Letters Patent should be read as corrected above, so that the same may conform to the record of the case in the Patent Oifice.

Signed and sealed this 1st day of May, A. D. 1951.

[SEAL] THOMAS F. MURPHY,

Assistant Oowz'ssz'oner of Patents.

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