ALUMINUM MUFFLER AND METHOD OF MANUFACTURE

Abstract: An aluminum muffler comprising an extruded aluminum tubular shell defining an inner space, at least one aluminum tube axially connected to said shell within said inner space, and end covers comprising apertures through which the at least one tube extends beyond the tubular shell, and method of making same.

Description: ALUMINUM MUFFLER AND METHOD OF MANUFACTURE The present invention relates to a muffler for motor vehicles that is highly corrosion and wear resistant made of aluminum. More specifically the invention relates to a muffler made from extruded aluminum profiles that are easily assembled together and to a method of manufacturing same. BACKGROUND OF THE INVENTION Mufflers for motor vehicles are presently made from sheet metal, particularly mild steel sheet metal. The metal sheets are rolled into cylindrical form and closed off at the ends with end covers. A tube, which may be perforated, usually also of mild steel, passes through the cylindrical form and through the end covers. Alternatively, two parallel tube sections are contained within the cylinder, each tube entering the cylinder from a different end, so that gases entering one tube expand into the volume of the cylinder and exit the cylinder through the other tube. The cylinder volume may also be filled with absorbing material to reduce sound and/or toxic gas emission. A major problem of these mufflers is that mild steel corrodes rather quickly and therefore the mufflers have to be replaced frequently. To use non-corroding stainless steel would make the mufflers too expensive for practical purposes. U.S. Patent No. 3,221,836 suggests one way to overcome this problem of corrosion by making a muffler from corrosion resistant metal such as aluminum or stainless steel. The patent thus discloses an aluminum muffler having a cylindrical body formed from aluminum sheet. A perforated aluminum tube extends through the center of the cylinder, and cast aluminum end covers close off the cylinder ends holding the tube in place within the cylinder. Various means of securing the end covers to the cylinder ends are disclosed. U.S. Patent No. 3,115,209 discloses a muffler made of rust proof material such as aluminum comprising a housing with removable end members having openings for passage of gases. A self-contained, unitary cartridge, including a tubular rigid member having open ends and a mass of shredded material providing an infinite number of surfaces for muffling gases, is removably contained in the housing. U.S. Patent No. 4,446,942 claims an aluminum muffler made by deep drawing a pair of hollow bodies and then joining the bodies together forming a muffler with a circumferential seam around its middle. An article in Popular Science vol. 176 No. 1 p. 62, 1960 also refers to a cast aluminum muffler with thicker metal at heat concentration points. In spite of all the benefits that would appear to come from using aluminum mufflers, such as corrosion resistance, lighter weight and possibly smaller size mufflers, aluminum mufflers, to the best of our knowledge, have not been commercial. SUMMARY OF THE INVENTION It is the object of this invention to provide an aluminum muffler that is simple to manufacture and cost competitive with convention sheet metal mufflers. Another object is to provide an aluminum muffler that is easy to assemble and longer lasting. A further object is to provide an aluminum muffler that is light weight and smaller in volume than a corresponding conventional muffler. It is also an object of this invention to provide a method of manufacturing an aluminum muffler by extrusion. In accordance with the above objective there is provided an aluminum muffler comprising an extruded aluminum tubular shell defining an inner shell wall and an inner shell space, at least one aluminum tube axially attached to and spaced apart from said inner shell wall within said inner space, and end covers comprising apertures through which the at least one tube extends beyond the cylindrical shell. In a preferred embodiment, the aluminum muffler comprises more than one tube, for example, two tubes, one tube extending through one end cover and the other tube extending through the other end cover. In another preferred embodiment, the tubular shell comprises a double wall defining an inner shell within an outer shell, with the tube attached to the inner shell. The tube inside the shell may be perforated to allow exhaust gas t expand into the space of the shell. This space and/or the space between the double tubular walls may also contain sound absorbing material to further reduce noise. In accordance with another preferred embodiment of the invention there is provided an aluminum muffler comprising an extruded aluminum tubular shell defining an inner shell wall and an inner space, at least one tube axially positioned within that space and slidably engaging the inner wall of the tubular shell, and end covers closing off the cylinder ends, said end covers comprising apertures through which the at least one tube extends beyond the tubular shell. A preferred method of engaging the tube with the inner wall of the tubular shell is by rail and track means. The aluminum muffler of this invention is made by using aluminum extrusion technology similar to that used in making aluminum profiles such as for door and window frames. Thus, the tubular inner and outer shells can be extruded together with the tubes and spacing strips as a single profile or the shells and tubes can be extruded separately with respective mating rails and tracks slidably engaging one another. It is obvious that the rails and tracks may be either on the shell walls or the tubes as long as these slidably engage one another. The end covers are preferably also made from aluminum, and may be cast or punched in any conventional manner known in the art. These end covers may be welded or folded over the cylinder ends as for example when sealing of cans, or they may be screwed or bolted to the cylinder. A sealing ring between the cover and tubular shell edge may also be used. In another preferred embodiment, each tube is attached to the tubular shell at more than one point by fixed bridging strips or mating rail and track in order to hold the tube more firmly and give it greater stability. Similarly, it is preferred that a double walled tubular shell preferably have the two walls spaced apart at three points. The term "tubular shell" as used herein is intended to include any extruded tubular profile irrespective of the cross-sectional shape. Thus, the shell may have a cross-section, for example, that is round, oval, hour glass, rectangular or custom contoured to fit under the motor vehicle. DESCRIPTION OF THE DRAWINGS The invention will be better understood when considered together with the following drawings in which: Figure 1 is a top plan view of an aluminum muffler in accordance with this invention; Figure 2 is a cross-sectional view of Figure 1 taken across A-A; Figures 3 and 4 show cross-sectional views of other embodiments of a muffler in accordance with this invention; Figures 5-9 are plan views of various ways of mounting end covers on the tubular shell; Figure 10 is a partial cut away perspective view of another embodiment of a muffler in accordance with the invention; Figure 11 is a cross-sectional plan view of the muffler of Figure 10; Figure 12 is a cross-section of the muffler of Figure 10 viewed from the inlet side; and Figure 13 is a cross-section of the muffler of Figure 10 viewed from the outlet side. DETAILED DESCRIPTION OF THE INVENTION Referring now to Figures 1 and 2, there is shown an aluminum muffler 10 having an outer shell 12 and inner shell 14. The outer shell 12 has three rails 16 and the inner shell 14 has three tracks 18 that slidably engage the rails 16, forming an air space between the inner 14 and outer 12 shells. Two tubes 24 and 26 have double rails 28 and 30 that are slidably engaged by tracks 32 and 34 located on the inner surface of cylindrical wall 14. Thus the tubes 24 and 26 can easily be slid axially into the inner cylinder 14 by means of the rails 28 and 30 and tracks 32 and 34, and the inner cylinder 14 can easily be slid into the outer cylinder 12 by means of rails 16 and tracks 18. end plates 36 and 38 cloe off the terminal ends of the cylindrical shell 12 leaving the ends 39 and 41 of tubes 24 and 26 protruding beyond the end plates 36 and 38 respectively, through apertures in these end plates. The tube ends 39 and 41 have the rail section 28 cut away leaving only round tube ends. The interface between the end plate apertures and the tube ends 39 and 41 can be sealed by welding so that the entire muffler is sealed with only the tube openings 40 and 42 providing passage for the entrance and exit of exhaust gases. The tubes 24 and 26 may be perforated (not shown) to allow the gases entering through them to expand in the cavity 44 of the inner shell 14. The air space 45 between the walls 12 and 14 of the muffler provides additional noise reduction. In a similar manner, a muffler can be manufactured with only a single cylindrical wall. In that case, the tubes 24, 26 engage the inner wall surface of the cylindrical wall directly. Referring now to Figures 3 and 4, there are shown cross-sections of alternative mufflers according to the invention. In Figure 3, all the axial elements of the muffler 50 are extruded as a single profile, with bridging strips 52 connecting the inner 54 and outer 56 cylindrical walls and bridging strips 58 connecting the tubes 24 and 26 to the inner wall 54. In Figure 4 the muffler 60 comprises a cylindrical extrusion having an inner 64 and outer 66 wall connected by bridging strips 62 and tubes 24, 26 slidably engaged via a rail and track 68 arrangement. In Figure 5 the end cover 70 is a flat plate through which tube 26 extends. The cover 70 is welded 72 all around the tube 26 and around the cylinder edge 74. In Figure 6 the end cover 80 has a bent flange 82 surrounding tube 26 and to which it is welded. Another bent flange 84 covers the outside cylinder wall 86 and is welded thereto, completely sealing the cylinder. Figure 7 illustrates another way of sealing the ends of the cylindircal shell. End cover 90 has a bent flange 92 surrounding tube 26 to which it is welded. A C-shaped bend 94 on the outer edge of the cover 90 is clamped over the cylinder wall 96 to form a seal. In Figure 8 is shown yet another way of mounting the end cover 90 to seal the cylinder 96. A collar band 98 is placed around the tube 26 and over bent flange 92 and tightened with bolt 93. End cover 90 is sealed over the cylinder 96 in the same way as in Figure 7. In Figure 9 the end cover 100 is tightened around tube 26 in the same manner as in Figure 8, by means of a collar band 98. The edge of the end cover 102, however, is sealed against the cylinder wall 96 by means of bolts 104 screwed into the track 106 which is integrally extruded with the cylindrical wall 96. A sealing gasket 99 assures that the seal between the cylindrical wall 96 and end plate 100 is complete. Referring now to Figures 10 to 13, there is shown another preferred embodiment of a muffler in accordance with the invention. Muffler 110 comprises a double walled shell defining an outer shell 112 and inner shell 114 connected by three equidistantly spaced connecting strips 116. Within the inner shell 114 there are positioned three axial tubes comprising an inlet tube 118, an outlet tube 120 and an extension tube 122. The inner shell 114 comprises axial track means 124 and the three tubes comprise axial rail means 126 so that the tubes can be slidably engaged and axially connected to the inner shell 114. A partition 128, which can be an extruded aluminum profile, axially connects inlet tube 118 and extension tube 122 by means of track 130 engaging rail 132 thus forming a chamber A. Outlet tube 120 engages extension tube 122 along their entire length by means of track 134 and rail 136, forming chambers B and C. Thus the tubes 118, 120 and 122 partition the shell 114 into axial chambers A, B and C. The inlet 118, outlet 120 and extension 122 tubes comprise perforations 138, 140 and 142 respectively along sections thereof. In the present embodiment, these perforations are facing the chamber C, but they could also face different chambers. Inlet tube 118 has a terminal u-shaped cut-out opening 144 opposite the inlet leading to chamber A, outlet tube 120 has a terminal u-shaped cut-out opening 146 opposite the outlet leading to chamber B, and extension tube 122 has two terminal u-shaped cut-out openings 148 and 150, the former leading to chamber A and the latter to chamber B. These openings 144, 146, 148 and 150 do not have to be u-shaped, nor at the terminal ends of the tubes, but can be anywhere along the tube. As the exhaust gases enter the muffler inlet tube 118 they flow to the end of the tube and enter chamber A through the u-shaped opening 144 where they expand. From there the gases flow via u-shaped opening 148 through the expansion tube 122 and exit at the other end through the other u-shaped opening 150 into chamber B. From chamber B the gases enter the outlet tube 120 through opening 146 and exit the muffler to the atmosphere. At the same time the gases expand from the three respective tubes 118, 120 and 122, into chamber C via the perforations 138, 140 and 142. The embodiment illustrated in Figures 10-13 encompasses additional advantages. In this embodiment there are created longitudinal chambers A, B and C which allow the exhaust gases to pass from all the tubes into chamber C via perforations 138, 140, 142 and from there to proceed along the pass from tube to tube through the u-shaped openings 144, 145, 148, 150. This results in a smooth flow of gases with minimum back pressure and noise. Mufflers providing longitudinal partitions as in this embodiment can also be manufactured from regular sheet metal or steel. Perforations 138, 140 and 142 do not necessarily have to face the same chamber, but can also face separate chambers. When extruding an aluminum muffler, it is possible to extrude the cylindrical shell with a hook shaped axial strip on the outside of the shell which can then be cut out to leave individual hooks for attaching the muffler to the underside of a vehicle. Similarly, an adjacent outer length of tube can be extruded with the shell, which can be cut out sections leaving loops. It will be appreciated by those skilled in the art that the invention is not limited to what has been shown and described hereinbefore by way of example. Rather, the scope of the invention is defined solely by the claims which follow.

Claims: CLAIMS 1. An aluminum muffler comprising an extruded aluminum tubular shell defining an inner space, at least one aluminum tube axially connected to said shell within said inner space, and end covers comprising apertures through which the at least one tube extends beyond the tubular shell. 2. An aluminum muffler as in Claim 1 wherein the tubular shell has a double wall. 3. An aluminum muffler as in Claims 1 and 2 wherein the at least one tube is at least partially perforated. 4. An aluminum muffler as in Claims 1 to 3 wherein the inner space of the muffler contains noise absorbing material. 5. An aluminum muffler as in claims 1 to 4 wherein the at least one tube is attached to the shell by two aluminum axial bridges. 6. An aluminum muffler as in claims 1-5 comprising an extruded aluminum tubular shell defining an inner space, at least one tube axially positioned within that space and slidably connected to the tubular shell, and end covers closing off the tubular shell ends, said end covers comprising inlet and outlet apertures through which the at least one tube extends beyond the tubular shell. 7. An aluminum muffler as in Claims 1-6 wherein the tubular shell, the at least one tube and connecting means are extruded as a single profile. 8. An aluminum muffler as in Claims 1-6 wherein the at least one tube is connected to the tubular shell by sliding engagement. 9. An aluminum muffler as in Claims 1-8 wherein the end covers are welded on to the tubular shell. 10. An aluminum muffler as in Claims 1-8 wherein the end covers are bolted on to the tubular shell. 11. An aluminum muffler as in Claims 1-8 wherein a gasket is interposed between the end covers and the tubular shell. 12. A method for making an aluminum muffler comprising extruding one or more muffler profiles including an outer tubular shell and at least one tube for axial positioning within said shell, cutting said profiles to the desired length and covering the ends of the shell with end covers having apertures to allow protrusion of the tube therethrough. 13. A method as in Claim 12 wherein the outer shell comprising axial rail or track means and the at least one tube comprising mating axial track or rail means respectively are extruded separately and assembled by sliding the at least one tube into the shell via the rail and track means whereby the tube extends beyond the shell, and covering the ends of the shell with aluminum covers having openings to allow the tube ends to protrude therethrough. 14. A method as in Claims 12 and 13 wherein the outer shell is a double layered shell with an air space in between and the tube being connected to the inner wall of the inner shell. 15. A method as in claim 12 comprising extruding the outer shell and the at least one tube in a single profile. 16. A method as in Claim 14 comprising extruding separately profiles of outer shell, optionally inner shell and at least one tube, each with slidable mating engaging means, and assembling said shell and tube together with end cover plates. 17. An aluminum muffler as in claims 1 to 11 comprising an inlet tube and an outlet tube, each axially connected to the shell within the inner space. 18. An aluminum muffler as in Claim 17, further comprising an extension tube axially connected to the shell and to the inlet and outlet tubes. 19. An aluminum muffler as in Claims 17 and 18, wherein the inlet, outlet and optionally extension tubes form separate axial chambers within the inner space of the shell. 20. An aluminum muffler as in Claims 17-19, wherein the tubes comprise terminal apertures. 21. An aluminum muffler as in Claims 17-20, wherein the tubes further comprise perforations. 22. An aluminum muffler as in Claim 19, wherein the tubes comprise perforations facing the same chamber. 23. A muffler comprising - a tubular shell defining an inner space enclosed by end covers, an inlet tube connected axially to the shell within the inner space and extending out from one end cover, an outlet tube connected axially to the shell within the inner space and extending out from the other end cover, and openings in the tubes inside the inner space to enable passage of exhaust gases from one tube to another and to the inner space. 24. A muffler as in Claim 23 comprising an additional extension tube confined within the inner space and having openings for exhaust gas passage therethrough from inlet tube to outlet tube. 25. a muffler as in Claims 23-24, wherein the axial tubes partition the inner space into separate chambers. 26. A muffler as in Claims 23-25, wherein the tubes have perforations on one side. 27. A muffler as in Claim 26, wherein the perforations on the tubes face the same chamber.

Inventors: FARBERMAN ZIV, FARBERMAN, ZIV
Applicants: FARBERMAN ZIV, KLIL IND LTD, FARBERMAN, ZIV, KLIL INDUSTRIES LTD.
Application year: 1999
Main classification: F01N
IPC codes: F01N1, F01N7