US3054474A

US3054474A - Muffling tubes

Info

Publication number: US3054474A
Application number: US739317A
Authority: US
Inventors: Lindsay M Applegate
Original assignee: Individual
Current assignee: Individual
Priority date: 1958-06-02
Filing date: 1958-06-02
Publication date: 1962-09-18
Anticipated expiration: 1979-09-18

Description

p 1962 M. APPLEGATE 3,054,474

MUFFLING TUBES Filed June 2, 1958 INVENTOR United States This invention is related to that of my Patent Number 2,805,730, issued Sept. 10, 1957.

The principal object of this invention is the production of a flexible tube combining the characteristics of an exhaust tube and sound-absorbent mufller for internal combustion engines. Another object is to produce such a tube in economical form which can be manufactured with a minimum number of parts in machinery of conventional design. Still .another object is a mufiiing tube which has a favorable internal diameter relative to external diameter consistent with good performance. Another object is to utilize the sound-absorbent characteristics of materials as effectively as possible within the limitations of overall dimensions. An object of the invention also is to achieve a favorable relationship of material and construction costs to muflling performance in a flexible tube. Another object is to produce a tube which permits flexibility in the dimensions of the components for the most effective internal configuration and the most economically effective relationship of dimensions, configuration and properties of sound-absorbent materials. And, still another object is to combine different materials in arrangements favorable to economical continuous manufacture, effective sound absorption and length of useful life in service.

What constitutes this invention is set forth in the specification following with reference to the accompanying drawing and is succinctly defined in the appended claims.

In the drawing, FIGURE 1 is a schematic side View, not to scale, partly sectional, showing the essential components of my invention in an enlarged diagrammatic form.

My invention is composed of four parts, 1, a metal strip formed and rolled spirally into a conventional flexible metal tube, two strips, 2 and 3 of sound-absorbent material such as woven glass fiber or asbestos and a metal strip 4.

Strips

2, 3 and 4 are interleaved and wound spirally along with strip 1 to be held between the overlapping edges 5 and 6 of strip 1, and formed so the

inner edges

7, 8, and 9 of

strips

2, 3 and 4 respectively protrude into the interior of the tube.

The principal purpose of metal strip 4 is to hold the

inner edges

7 and 8 of

fibrous strips

2 and 3 radially into the interior of the tube. Also in my present invention, two sound-

absorbent strips

2 and 3, one on each side of the metal strip 4, increase the sound-absorbent ability of the tube to attain results which cannot so readily be accomplished with a single strip of soundabsorbent material.

Strip 4, being formed with a considerable portion of width rolled radially and projecting into the interior of the tube is preferably of metal easily formed into an edge-wound spiral. Some wrinkling of the inner edge 9 of strip 4 is to be expected but this is not .an impairment.

Strip 2 will not always remain close to strip 4 as shown in the drawing but may tend to assume a different configuration. The sound-absorbent effect of strip 2 in either case is effective.

A modification of FIGURE 1 of my present invention for economy is accomplished by omitting either strip 2 or strip 3 and retaining only one sound-absorbent strip along with metal strip 4. Either arrangement would be effective, the choice being a matter of design.

atent In the operation of my present invention it is sometimes desirable to take account of the direction of flow of gas through the tube. For example, it may be desirable to utilize the baflling effect of the inward projecting surface of strip 4 to protect strip 3 from the direct impact of gas flow, or conversely to protect strip 2 in the other direction.

If strip 2 occupies a position as shown in the drawing but without strip 3, and the flow of gas is oriented to impinge on strip 4 in advance of strip 2, the baffling and heat-absorbing ability of strip 4 will protect strip 2 from all but turbulent contact of gas on strip 2, and strip 2 will be required only to absorb sound energy with a minimum of erosion thereon from the moving gas.

The mechanical processes of manufacture of flexible tubes with interleaved fibrous strips are known in the art wherein a paper strip is sometimes combined with a flexible steel tube to produce a paper-lined flexible tube for carrying wires in electrical work. There has been invented, also, a flexible tube with an interwound metallic strip intended for use .as a mufliing tube. Thus the mechanical technology for the construction of my invention has already in part been developed.

My invention is distinguished from the most nearly comparable prior art in that I use one or two strips, 2 and 3, of fibrous material for absorbing sound energy together with a metal strip, 4, for positioning and protecting the sound-absorbent strip. The prior art showing only a metal strip depends primarily upon turbulence as distinguished from a combination of turbulence and direct sound absorption as accomplished in my present invention.

The acoustic principles of the use of sound-absorbent fibrous materials and the desirability of using materials such as asbestos or fiber glass have been set forth in my issued patent referred to above. The advantages of flexible tubing for muffling and the advantage of a minimum of baffling in muflling systems also have been presented in the above mentioned patent. My present in vention has, in common with my other invention the advantages of compactness, minimum baffling, and the effective use of sound-absorbent materials. The

soundabsorbent strips

2 and 3 in my present invention should for this use be combustion resistant. Permeability and a large effective fiber area are desirable for maximum effect of sound absorption.

In determining the dimensions in my invention it will be observed that the ordinary mufiler is usually only about two or three feet long, but that the total length of exhaust pipe and muffler is usually ten feet or more. The muffling effect per foot of tube as made in this invention can be about one-fourth of that of a conventional muflier and still, by virtue of employing a length of mufller tubing equal to that of the usual exhaust pipe and mufller be as efiiective as the conventional mufller. An internal diameter of one and one-half to two inches in tube 1 for example, and moderate internal extension of

strips

2, 3 and 4 allow a structure that is economical, reasonably compact, and effective for conventional vehicles.

I claim:

1. A flexible tube formed of an overlapping continuous metal strip, wound and interleaved with a plurality of continuous strips of fibrous material and a second continuous strip of metal paralleling said fibrous strip, said strips of fibrous material and said second strip of metal being formed to project into the interior of the formed tube.

2. A flexible tube formed of a continuous metal strip with overlapping edges, two fibrous strips and a second metal strip, said fibrous and second metal strips interlocked between the overlapping edges of the first said 3 metal strip, and projecting radially into the interior of the formed tube.

3. A spirally wound mufliing tube formed of a resilient flexible strip formed with overlapping edges, a plurality of resilient flexible sound-absorbent strips interlocked therein, and a metal strip paralleling said sound-absorbent strip also interlocked therein, said sound-absorbent strip and said paralleling metal strip projecting into the interior of the wound tube.

4. A mutfling tube comprising a spirally wound strip with overlapping edges, a plurality of strips of fibrous sound-absorbent material interlocked therein and project ing inwardly toward the center of said tube, and a metal strip paralleling said fibrous strips and interlocked therewith, also projecting inwardly toward the center of the tube.

5. A muflling tube comprising a spirally wound strip with overlapping edges, two strips of sound-absorbent material and a strip of metal paralleling said soundabsorbent strips and interlocked between said overlapping edges, and projecting into the interior of the wound tube.

6. A mufiiing tube comprising a spirally Wound strip with overlapping edges, two strips of sound-absorbent material and a strip of metal between them, the three strips being interlocked between said overlapping edges, and projecting into the interior of the wound tube.

7. A muffling tube comprising a spirally wound strip with overlapping edges, two strips of sound-absorbent material and a strip of metal between them, the three strips being interlocked between said edges and projecting radially inside the resultant tube.

8. A mufiling tube comprising a spirally wound strip with interlocking edges, twostrips of sound-absorbent material and a strip of metal between them, the three strips being interlocked between said edges and projecting substantially radially into the interior of the resultant tube.

9. A muflling tube comprising a spirally wound strip with interlocking edges, two strips of sound-absorbent 4- material and a strip of metal between them, the three strips being interlocked between said edges, and projecting into the interior of the resultant tube, the metal and one fibrous strip projecting approximately radially toward the center of said tube.

10. A flexible tube comprising a spirally wound strip with over-lapping edges, a metal strip and a plurality of fibrous strips retained between said overlapping edges, and formed so they project inwardly into the resultant tube.

11. A flexible tube comprising a spirally wound strip with overlapping edges, a metal strip and two fibrous strips each retained over part of their width between said overlapping edges, and formed so part of the width of said metal and fibrous strips project inwardly into the resultant tube.

12. A flexible tube comprising a spirally wound strip with overlapping edges, a metal strip and two fibrous strips each retained over part of their width between said overlapping edges, and formed so they project at the unretained edges for a portion of their width into the interior of the resultant tube.

13. A flexible tube comprising a spirally wound strip with overlapping edges, a metal strip and at least one fibrous strip, each retained over their edges and part of their respective widths between said overlapping edges, and formed so their other edges and a portion of their widths project into the interior of the resultant tube.

References Cited in the file of this patent UNITED STATES PATENTS 1,015,698 Maxim Jan. 23, 1912 1,115,873 Spencer Nov. 3, 1914 1,530,324 Pribil Mar. 17, 192.5 1,909,511 Wilson May 16, 1933 2,014,368 Blundell Sept. 17, 1935 2,718,273 Deh us Sept. 20, 1955 2,805,730 Applegate Sept. 10, 1957