FILLER ELEMENT FOR A TANK AND METHOD OF MANUFACTURE

Abstract: The filler elements (14) for a tank (12) of combustible fluid are formed from a sheet of foil mesh material by a multiple fold technique. The folding process places the free edges of the sheet in the center of the filler element where they are protected and where any piece that breaks off will be trapped. The sides are first folded inwardly and then the ends are folded inwardly. Finally, this intermediate folded member is rolled, formed, molded or folded further into the final desired shape for the filler element. Folding is facilitated by use of a crushed crease along desired fold lines. To reduce nesting of the mesh, various sections of the mesh corresponding to the fold lines present openings of differing sizes. Various filler elements not formed from a sheet may also have any free extremities or edges thereof coated to control "flaking". If desired, the formed filler elements may also be coated exteriorly with the thermally conductive, hydrocarbon compatible sealant.

Description: FILLER ELEMENT FOR A TANK AND METHOD OF MANUFACTURE BACKGROUND OF THE INVENTION 1. Field of the Invention. The present invention relates generally to receptacles for combustible materials, such as fuel tanks. More particularly, this invention relates to an improvement in the filler mass inserted in such tanks to prevent explosion. Specifically, the invention relates to the design of discreet filler elements which are used to fill a tank and to coating the edges of a sheet of foil mesh with a hydrocarbon compatible, thermally conductive sealant prior to forming the sheet into the filler element. 2. Description of the Prior Art. It is well known in the prior art that a filler mass insert for a tank may be formed from a metal foil mesh and will act to prevent explosion by transmitting heat from hot spots occurring on the tank exterior. This filler mass is traditionally formed of multiple layers of an expanded metal foil (U.S. Patent No. 3,356,256), the methods of manufacture thereof being well established in the art (U.S. Patent No. 4,921 ,118). The resulting multi-layer mass can be either rolled into a coil, cut into pieces and stacked, or fan-folded (U.S. Patent No. 4,149,649) to yield a filler mass of the size and shape of the cylindrical or rectangular tank to be fitted (U.S. Patent No. 4,566,589). More recently, various filler mass elements have been formed from foil material in order to retro-fit existing tanks and to accommodate tanks of irregular shape. These designs have not been entirely successful for a variety of reasons; but most importantly, because they all exhibit free edges which break off during use and then clog fuel lines (typically referred to as "flaking"). As an example, in U.S. Patent No. 4,613,054 a spherical shaped filler element is disclosed. This filler element begins as a continuous sheet of mesh, is rolled into a cylinder, severed from the sheet, and finally crushed into a ball shape. It can readily be seen that this process creates a discreet, compacted filler element that, as a result of the construction process, will allow the mesh layers to "nest" and will leave exposed free edges on the exterior of the sphere. Moreover, the final crushing step compacts this filler element, reducing the available open interior space and thereby reducing its effectiveness as a filler mass. Similarly, in U.S. Patent No. 5,000,336 another design for cylindrical and spherical discreet filler elements is presented. A strip of foil mesh having holes of irregular size is rolled into a cylindrical filler element and compressed into a sphere. By using holes of irregular size in the mesh, nesting of the mesh layers is reduced, but the problem of "flaking" from exposed edges is not resolved. In U.S. Patent No. 4,927,045 a different filler mass element is proposed which is described as having a long supporting memberwith a multitude of projecting plates. This element is used to retro-fit tanks with a filler mass by inserting the element through the tank opening; but the extensive number of free edges radiating from the supporting member in this design increases the "flaking" problem many fold, thereby preventing its use in any application where a clogged fuel line would pose an unacceptable risk. SUMMARY OF THE INVENTION Accordingly, it is the principal objective of this invention to provide a design for a discreet filler element which will eliminate the "nesting" and "flaking" problems inherent in the prior art. It is a further objective to present such a design for a filler element which can be easily formed into a variety of shapes with minimal crushing to preserve the effectiveness of the filler mass. The filler elements of the present invention are formed from a sheet of foil mesh material, or the like, by a multiple fold technique. The folding process places the peripheral free edges of the sheet near the center of the filler element where the edges are protected and where any piece that should break off will be trapped. For a rectangular sheet, the opposing sides are first folded inwardly along a crushed crease and then the opposing ends are similarly folded inwardly along a crushed crease. This creates an intermediate folded member which can then be rolled, molded, formed or folded again into a final desired shape for the filler element. To eliminate nesting of the mesh within the filler element, various sections of the mesh corresponding to the folds are arranged to present openings of varying sizes, such that, when folded, sections of differing sized openings are juxtaposed. In one method of the present invention for manufacturing a filler mass insert element for a tank, the edges of a sheet of foil mesh are coated with a hydrocarbon compatible, thermally conductive sealant prior to forming the sheet into the filler element. The filler element may then be folded into a packet, rolled into a cylinder, or otherwise formed according to any other means known in the art. Additionally, filler elements which are not formed from a sheet, such as the tank retro-fit elements, may similarly have the free extremities thereof coated in accordance with the present invention to control "flaking". In a further feature of the invention, the formed filler elements may also be coated externally with the sealant. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a tank filled with a plurality of filler mass elements in accordance with the present invention. FIG. 2 is a perspective view of a filler mass element utilized in FIG. 1. FIG. 3 is a perspective view of a portion of a sheet of expanded metallic foil mesh for use in forming the filler mass element. FIG. 4 is a perspective view of a rectangular sheet of metallic foil mesh for use in forming the filler mass element of FIG. 2. FIG. 5 is an end view of the sheet of FIG. 4 illustrating the first fold for the filler mass element. FIG. 6 is an end view of the sheet of FIG. 4 illustrating the completion of the fold of FIG. 5. FIG. 7 is a perspective view of the sheet of FIG. 4 following the fold of FIG. 6 and beginning the next fold in sequence. FIG. 8 is a perspective view of the intermediate folded member resulting from completion of the fold of FIG. 7. FIG. 9 is a perspective view of an alternate form of the filler mass element. FIG. 10 is a perspective view of yet another alternate form of the filler mass element. FIG. 11 is a perspective view of a sheet of foil mesh coated along its periphery, in accordance with the present invention, for use in forming a filler mass element. FIG. 12 is a cross-sectional perspective view of a formed filler mass insert element incorporating the sheet of FIG. 11 and also employing an outer coating. FIG. 13 is a cross-sectional perspective view of another filler element coated in accordance with the present invention. FIG. 14 is a perspective view of yet another filler mass insert element used to retro-fit tanks, shown incorporating the coating method of the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS Turning first to FIG. 1 , there is illustrated a tank 12 having a plurality of fuel permeable filler mass insert elements 14 stacked therein to form a thermal filler mass within the tank. While only a portion of the tank 12 is shown here for clarity, in practice an entire closed tank with an access opening us used, as is well known in the art. Also, the entire tank is filled with the filler elements, such that they are in thermal contact with one another and with the tank walls. During manufacture of the tank, the insert elements may be stacked inside before the tank is closed, or alternatively, the filler elements may be manufactured in a size small enough to be inserted through an access opening of the tank after the tank is completed. A filler element in accordance with the present invention, such as is depicted in FIGS. 2, 9 and 10, is formed from a sheet of expanded metallic foil mesh 22 (see FIGS. 3 and 4), having longitudinal sections of large openings 24 and small openings 26 defined thereon, and having exposed free edges along its periphery. (While a rectangular sheet is shown, it should be readily apparent that any geometrical shape can be used to create an equivalent filler element in accordance with the teachings of this invention and that the expanded foil mesh described herein may be replaced by other perforated foil equivalents known in the art.) In the preferred embodiment, the longitudinal sections of large openings 24 and small openings 26 correspond to the first fold lines used in the construction of the filler element to thereby juxtapose these differing sized openings in the completed filler element. As an alternative variation, the sizes of the mesh openings can be mixed within a particular longitudinal section or they can be randomly disposed across the section. A portion of a foil mesh sheet 22 for use in constructing the filler element is shown in detail in FIG.3. Although it is possible to bend the foil sheet where folds are desired, preferably there is disposed nearthe boundary between longitudinal sections of differing hole sizes a crushed line 28 (shown as a dotted line). This crushed line functions as a crease along the desired fold line for facilitating the construction of the filler element. The beginning of the construction of the filler element is shown in FIGS. 4, 5 and 6, where first opposing side peripheral edges 32 and 34 are folded inwardly along crease lines 32a and 34a, respectively, to place these side free edges near the center of the sheet. Turning now to FIG. 7, second opposing peripheral end edges 36 and 38 are next folded inwardly along crease lines 36a and 38a to place these end free edges near the center, thereby creating the intermediate folded member shown in FIG. 8. By applying a final finishing fold to this intermediate folded member, such as indicated by the arrow 40, the filler element becomes the rectangular filler element packet 14 shown in FIG. 2. Clearly, different final shapes of the finished packet can be obtained by varying the finishing fold or folds applied to the intermediate folded member or by reforming the finished packet. As an example, the packet of FIG. 2 may be further formed by a press or mold into a variety of shapes, such as the cylindrical shape 50 shown in FIG. 10. Alternatively, the intermediate folded member of FIG. 8 may be formed into a finished packet without the final fold 40, such as by rolling it to form the cylindrical shape 60 shown in FIG. 9. Finally, means for securing the packet, such as a metallic band 72, is attached to the finished packet to keep it intact. Alternatively, gluing, soldering, welding, or other means known to the art, may also be used. Referring now to FIG. 11 , there is illustrated therein a sheet of foil mesh 110, the manufacture of which is well known to the art. In accordance with the method of the present invention, this sheet of mesh is coated 112 along its peripheral free edges with a sealant to secure the free edges of the sheet and to prevent "flaking" of any edge pieces. In the preferred embodiment, the sealant is a hydrocarbon compatible, thermally conductive adhesive sealant, such as the commercially available product from 3M Corporation known as E.C. 776. This type of sealant does not deteriorate in the corrosive environment of the fuel tanks, readily transmits heat to the foil mesh, and securely adheres to the foil. Once the sheet of foil mesh is prepared with the edge coating described above, it can then be formed into a wide variety of filler mass insert elements which will now inhibit "flaking" due to the sealant control placed on the edges of the sheet. For enhanced security, the flake trapping design of the filler element 120, shown in FIG. 12, can be formed from the above described edge coated sheet to further secure the edges from "flaking". This filler element is formed by folding the foil sheet 110 in such a manner as to position all of its edges within the interior of the packet. The method of folding to create this insert packet is described above. Once a sheet of foil mesh is formed into a filler element, it may optionally be coated 122 externally with the same sealant as that used to coat the edges of the sheet. This external coating of the sealant acts as yet another level of security by trapping any edge particles which, although unlikely, may still somehow "flake" off of the edge of the foil sheet and escape the edge coating 112. Turning now to FIG. 13, there is shown a cutaway perspective view of a "flaking" inhibited rolled cylindrical filler element 130 formed from an edge coated sheet of foil as shown in FIG. 11 and discussed above. When so rolled into a cylindrical shape, one sealant coated edge 132 is disposed in the interior of the cylinder while another sealant coated edge 134 is disposed on the exterior of the cylinder. The remaining two sealant coated edges of the rectangular sheet form the extremities of the cylinder. Once rolled into a cylindrical form for installation into a tank, this filler element may optionally be coated 136 over its entire exterior with the same hydrocarbon compatible, thermally conductive sealant used to coat the edges. Finally, the coating method the present invention may also be applied to a tank retro-fit filler element design, as shown in FIG. 14 and more fully described in U.S. Patent No. 4,927,045. This retro-fit filler element 140 has a central elongated mounting member 142, such as a wire, holding a plurality of radially disposed foil members 144. To present "flaking", the projecting ends of the radial foil members are coated 146 with the hydrocarbon compatible, thermally conductive sealant. Accordingly, when this foil insert member is installed into a tank, the tendency for "flaking" is reduced by the protective coating which now secures the projecting ends of the foil members and retains any piece that should break off. From the foregoing description, it will be apparent that modifications can be made to the apparatus and method for using same without departing from the teachings of the present invention. Accordingly, the scope of the invention is only to be limited as necessitated by the accompanying claims.

Claims: CLAIMS I Claim: I . A filler element for a tank comprising: a packet formed from a sheet of foil mesh, said packet having its peripheral edges disposed internally of the packet. 2. The filler element of claim 1 wherein said sheet of foil mesh is rectangular in shape and said peripheral edges thereof are folded inwardly. 3. The filler element of claim 2 further comprising creases defined on said sheet of foil mesh for facilitating said folds. 4. The filler element of claim 2 wherein said packet comprises an intermediate folded member, wherein said intermediate folded member comprises first opposing edges of said rectangular sheet of foil mesh folded inwardly and second opposing edges of said sheet of foil mesh folded inwardly. 5. The filler element of claim 4 wherein said intermediate folded member is folded to form said packet. 6. The filler element of claim 5 wherein said packet is further formed into a cylindrical shape. 7. The filler element of claim 6 further comprising means for securing said packet. 8. The filler element of claim 4 wherein said packet comprises a roll of said intermediate folded member. 9. The filler element of claim 8 further comprising means for securing said packet. 10. A filler mass for a tank comprising: a plurality of packets formed from an intermediate folded member, wherein said intermediate folded member comprises a sheet of foil mesh having the peripheral edges thereof folded inwardly. I I . The filler insert for a tank of claim 10 wherein said packet is further formed by folding said intermediate folded member. 12. The filler insert for a tank of claim 11 wherein said packet is further molded into a desired shape. 13. The filler insert of claim 10 wherein said packet is further formed by rolling said intermediate folded member. 14. The filler insert of claim 11 further comprising means for securing said packet. 15. The filler insert of claim 12 further comprising means for securing said packet. 16. The filler insert of claim 13 further comprising means for securing said packet. 17. A method of forming a filler mass element for a tank comprising the steps of: forming a sheet of foil mesh of predetermined size and shape; and folding said sheet of mesh to form an intermediate folded member by positioning the peripheral edges thereof inwardly. 18. The method of claim 17 further comprising first forming sections in said mesh, wherein said sections exhibit openings of differing sizes and said sections correspond to said folds. 19. The method of claim 17 further comprising folding said intermediate folded member. 20. The method of claim 17 further comprising rolling said intermediate folded member. 21. A method for manufacturing a filler element for a tank comprising the steps of: coating edges of a sheet of foil mesh with a sealant; and forming said sheet of foil mesh into the filler element. 22. The method of claim 21 wherein said sealant comprises a thermally conductive, hydrocarbon compatible material. 23. The method of claim 22 wherein said sealant comprises an adhesive. 24. The method of claim 21 further comprising coating the exterior of said formed filler element with said sealant. 25. The method of claim 24 wherein said seal comprises a thermally conductive, hydrocarbon compatible material. 26. The method of claim 25 wherein said sealant comprises an adhesive. 27. A filler element for a tank comprising: a sheet of foil mesh, having edges defined thereon, wherein said sheet is formed into a filler element; and a coating of sealant disposed along edges of said sheet of foil mesh. 28. The filler element of claim 27 wherein said sealant comprises a hydrocarbon compatible, thermally conductive material. 29. The filler element of claim 28 wherein said sealant comprises an adhesive. 30. The filler element of claim 27 wherein said sheet of foil mesh is folded into a packet, having the peripheral edges thereof disposed internally of the packet, to form said filler element. 31. The filler element of claim 27 wherein said sealant comprises a hydrocarbon compatible, thermally conductive material. 32. The filler element of claim 27 wherein said sheet of foil mesh is rolled into a cylindrical shape to form said filler element. 33. The filler element of claim 32 wherein said sealant comprises a hydrocarbon compatible, thermally conductive material. 34. The filler element of claim 30 wherein the exterior of said formed filler element is coated with said sealant. 35. The filler element of claim 32 wherein the exterior of said formed filler element is coated with said sealant. 36. The filler element of claim 34 wherein said sealant comprises a thermally conductive, hydrocarbon compatible material. 37. The filler element of claim 35 wherein said sealant comprises a thermally conductive, hydrocarbon compatible material. 38. A filler insert for a tank comprising: a central elongated mounting member; a plurality of foil members radially affixed along said mounting member; and a coating of sealant disposed on the projecting ends of said foil members. 39. The filler insert of claim 38 wherein said sealant comprises a thermally conductive, hydrocarbon compatible material. 40. The filler insert of claim 38 wherein said sealant comprises an adhesive.

Inventors: FENTON RONALD L, FENTON, RONALD, L.
Applicants: FENTON RONALD L, FENTON, RONALD, L.
Application year: 2000
Main classification: D04H9
IPC codes: A62C3, B60K15, B64D37, B65D90, F17C13