US3311696A - Electrically and thermally conductive shield - Google Patents

Description

March 28, 1967 D. A. MELNICK 3,311,696

ELECTRICALLY AND THERMALLY CONDUCTIVE SHIELD Filed June 18, 1965 2 Sheets-Sheet l INVENTOR. DOA/4A0 4. M54 A/lCAf,

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28, 1967 D. A. MELNICK ELECTRICALLY AND THERMALLY CONDUCTIVE SHIELD Filed June 18, 1965 2 Sheets-Sheet 2 AV Av INVENTOR.

United States Patent 3,311,696 ELECTRICALLY AND THERMALLY CONDUCTIVE SHIELD Donald A. Melnick, 7301 Birch Ave., Takoma Park, Md. 20012 Filed June 18, 1965, Ser. No. 465,043 11 Claims. (Cl. 174-18) This invention relates to electrically or thermally conductive web or sheet material, and more particularly to conductive tape or sheet material for use in covering immersion heating electrodes, freezer units, or similar elements employedfor conduction of electrical current or heat to or. froma contiguous adjacent medium, wherein it is desirable vto protect the electrodes or corresponding unit from undesired deposits from said medium.

A main ,object of the invention is to provide a novel andimproved expendablecovering material for electrodes, freezer units, or the like, the covering material being of simple construction, providing highly efficient conduction, and being easy to install and remove.

A further object .of the invention is to provide, an improved web or sheet material for use in covering electrodes, freezer units, or similar elements wherein electrical current or heat is to be conducted to or collected from a surrounding medium, the web or sheet covering material serving as a means for collecting sediment, frost, or other undesired deposits from the surrounding medium, the material being inexpensive to fabricate, being rugged in construction, being sufficiently pliable to accurately conform with the surfaces to which it is to be applied, and being easy to strip off for unloading or replacement.

A still further object. of the invention is to provide an improved expendable tape or sheet material for use as a protective conducting cover for electrodes, freezer units, and similar elements exposed in a medium, primarily fluid mediums, either liquid or gaseous, wherein there is a tendency for material to be deposited on the elements .being protected, the covering material serving to receive such deposits and to eliminate the necessity of cleaning the elements, the material being relatively thin and pliable as well as being highly conductive, andbeingconstructed so that it does not in any way interfere with the normal operation of the elements covered thereby.

Further objects and advantages of the invention will become apparent from the following description and claims, and from the accompanying drawings, wherein:

FIGURE 1 is a perspective view of a length of adhesive tape material constructed in accordance with the present invention and shown with a portionof the outer metal foil layer thereof separated from the remainder thereof to clarify structural details.

FIGURE 2 is an enlarged transverse vertical cross sectional view taken substantially on the line 2-2 of FIGURE 1.

FIGURE 3 is a perspective view, partly in cross'section, taken through an electrical vaporizer assembly whose electrodes are covered with conductive tape material such as that shown in FIGURES 1 and 2.

FIGURE 4 is an enlarged elevationalview of the electrodes of the vaporizer of FIGURE 3, one of the protective tape elements being shown partly detached from its associated electrode so as to illustrate the manner in which the tape elements are applied to the electrodes.

FIGURE 5 is an enlarged horizontal cross sectional view taken substantially on the line. 55 of FIGURE 4.

FIGURE 6 is a perspective view of a piece of wide covering material in the form of a relatively wide web for use in covering refrigerator freezer units, or similar large freezing or other thermal-active surfaces, a corner portion of the mateial being opened up to reveal the internal construction of the material.

FIGURE 7 is a perspective view of a typical refrigerator freezer unit and illustrating the manner in'which a sheet of the material shown in FIGURE 6 is applied thereto'for the purpose of acting as a frost collector.

FIGURE 8 is a perspective view showing a fragmentary portion of an alternative form of conductive sheet material which may be employed in the same manner as the material shown in FIGURE 6.

FIGURE 9 is a perspective view showing still another alternative form of conductive material which may be em ployed in the same manner as the material shown in FIG- URES 6 and 8.

Referring to the drawings, and more particularly to FIGURES 1 to 5, 11 generally designates a typical form of expendable pliable tapematerial which may be employed in accordance with the present invention to cover electrode elements for the purpose of protecting said electrode elements against direct accumulation thereon of sediment or scale material, since such deposits ordinarily require considerable effort and time in scraping off and removing the deposits. The protective tape material 11 therefore is employed to cover such electrodes and to collect the undesirable deposits, the tape material being easy to apply to the electrodes and being similarly easy to strip off the electrodes after a considerable amount of scale or other deposits have accumulated thereon. After removal, the tape material may be merely discarded or, if so desired, may be suitably laundered or cleansed and reused.

The tape material 11 comprises an outside layer 12, which may consist of pliable metal foil, such as aluminum foil, or the like. Secured in any suitable manner to the bottom surface of the outer conductive metallic layer 12 is a relatively wide mesh metallic screen or grid 13 of fine wire material coextensive in width with the outer metal foil strip 12 and conductively integral therewith. The spaces in the wire mesh material 13 are filled with adhesive material 14'of any conventional composition, for example, of the same composition as is employed in ordi-- nary pressure-sensitive adhesive tape, the material being preferably of a type having stability over a wide temperature range, including the boiling point temperature of water or of other liquids which may be employed in the devices with which the tape is intended to be used. There are many commercial adhesive materials which are suitable for this purpose and which are capable of adhering to both the metallic portions of the tape 11 and to themetal electrode surfaces with which the tape is employed at the operating temperatures of the electrodes. The thickness of the layer of adhesive material 14 is sub-' stantially identical with the thickness of the wire mesh screen 13 so that when the tape is installed on a stationary electrode the wire mesh screen 13 makes electrical contact with the electrode as well as being electrically connected with the outer metallic foil strip 12, whereby said outer metallic strip 12 becomes electrically connected to the electrode so that there is no electric field between the tape and the electrodeand hence there is no heating, bubbling or deposit of sediment in this region.

In using the covering tape 11, suitable lengths thereof are cut off and are respectively installed on the electrodes to be protected, for example, the pair of electrodes 15 and 16 of a conventional water vaporizer 17 shown in FIGURE 3. The strips of tape 11 are of sufficient length to cover the major portions of-the surfaces of the electrodes 15 and 16 and to extend a short distance below the electrodes. The strips of tape 11 are placed lengthwise on the electrodes and tightly wrapped around same in the manner illustrated in FIGURE 4, forming a lengthwise overlapping seam at their meeting vertical margins, with the bottom portion of the strip bent horizontally and outwardly, as shown at 19 in FIGURES 4 and 5. The outwardly projecting tab elements 19 provide a means for grasping and manipulating the lower portion of the tape when it is to be unwrapped and stripped off the electrodes after a considerable period of use during which substantial deposits of sediment have collected on the exposed outer metallic foil elements 12.

As will be readily apparent from FIGURE 2, the grid wires 13 are located so as to make good electrical contact with the surfaces of the electrodes 15 and 16, so that the covering strips of tape 11 act as electrical extensions of the electrodes and provide efficient conduction of electric current to the liquid in which the electrodes are immersed.

To remove the covering strips of conductive tape 11, the tabs 19 are merely bent downwardly to vertical positions, providing access to the bottom corners of the overlapping margins ofthe strips, whereby said margins may be disengaged from each other and whereby the stfip may be easily detached from the electrodes.

The wire elements of the wire mesh layers 13 are preferably flattened at their points of transverse crossing, as shown at 40, so as to maintain the thickness of the wire mesh layers 13 substantially uniform throughout.

Although the electrodes 15 and 16, illustrated in FIG- URES 4 and 5 are generally cylindrical in shape, the conductive tape material 11 may be also employed with equal efficiency with electrodes of other cross sectional shape.

As will be presently described, the screen material 13 may be formed integrally with the outer covering layer 12, and does not necessarily have to be in the form of a two-dimensional grid. It may be in the form of a onedimensional array of linear elements which protrude through the adhesive layer 14, or it may simply be an array of spaced dot elements which similarly protrude through the adhesive.

Referring now to FIGURES 6 and 7, 11' designates a web of material similar in construction to the relatively narrow tape material 11 shown in FIGURE 1, and comprising an outer layer of pliable metal foil 12', a grid of pliable thin wide-mesh pliable wire material 13', and a layer of adhesive material 14 similar to that employed in the embodiment of FIGURE 1 and filling the spaces of the wire mesh material 13 while allowing the wire mesh to be exposed at the bottom of the sheet 11'. The material 11' may be employed as a protective cover to facilitate defrosting of the freezer units of refrigerators, deep freeze equipment, or the like. Thus, the web material 11 is preferably of at least sufficient width to span the depth of a conventional refrigerator freezer unit 20, shown in FIGURE 7. A suitable length of the web material 11' is cut 011?, preferably sufficient to completely cover the thermally conductive wall surface 21 of the freezer unit 20 which contains the evaporation coil channels 22. Where possible, the web material 11 is also applied to the inside wall surface 21a and shelf 25. As shown in FIGURE 7, the web material is applied so as to project beyond the end 28 of the freezer unit 20 to prevent the accumulation of frost around the edge of the open end and to facilitate the removal of the web material with the accumulated frost thereon.

The length of conductive web material 11 is applied to the wall surface of the freezer unit 20, and is sufiiciently pliable so that it closely conforms to the contour of said wall surface and adheres thereto by the adhesive action of the material 14' incorporated in the cover element 11'. The wire mesh elements 13' are in thermally conductive contact with the surface of the freezer unit wall 21 substantially over the entire area of the covering material, so that heat is conducted to the foil outer layer 12 from the interior of the associated refrigerator and then to the wall surface 21 and freezer unit coil channels 22 through the conductive wire mesh layer 13'. Therefore, the thermal eficiency of the freezer unit 20 is in no way impaired, while at the same time accumulations of frost occur on the protective covering member 11' rather than directly on the wall surface 21 of the freezer unit. After a substantial amount of frost has accumulated on the cover sheet, the sheet is merely stripped off the freezer unit, and may be replaced by another protective sheet 11'. The previously used protective cover sheet may be allowed to thaw out in a sink or bucket, whereby the cover sheet may be reused, if so desired.

In order to decrease the amount of chopping of ice required to remove the sheet adjacent the edges thereof, the sheet is preferably somewhat greater in width than the depth of the freezer unit 20, so that the edges of the protective cover sheet 11' protrude beyond the edges of the wall of the freezer unit. It is preferable to employ a somewhat denser conductive grid in the modification shown in FIGURES 6 and 7 than was employed in the form of the invention illustrated in FIGURES 1 to 5 so as to avoid presenting too high a thermal resistance through the grid 13'. The metal of the grid 13 preferably should cover at least an area of the order of ten percent of the area of the conductive outer metallic foil layer 12 in order to prevent too high a thermal resistance through the grid. It is also preferable to employ an outer foil layer 12' of substantial thickness, whereby "to assist, by lateral conduction, in bridging any areas of imperfect contact between the grid 13' and the adjacent surfaces of the freezer wall 21.

FIGURE 8 illustrates a modification of the webbing material 11' wherein the pliable grid, designated at 23,

-is formed integrally with the pliable main foil element 12 of the cover sheet, shown at 24. The spaces in the integral pliable grid 23 are filled with the adhesive material 14 in the same manner as illustrated in FIGURE 6. As previously mentioned, instead of employing a twodimensional grid arrangement, a one-dimensional array of parallel ribs or line elements may be used, formed intergally with the pliable conductive foil member 12 and exposed through the adhesive material 14'. As a further alternative, the conductive intervening screen employed with the foil sheet 12 may comprise an array of dot-like projections 26, as shown in FIGURE 9, said projections being formed integrally with the foil sheet 12' and exposed through the layer of adhesive material, shown at 27 in FIGURE 9.

While certain specific embodiments of an improved conducting covering member for use with electrical or thermal-active elements have been disclosed in the fore going description, it will be understood that various modifications within the spirit of the invention may occur to those skilled in the art. Therefore, it is intended that no limitations be placed on the invention except as defined by the scope of the appended claims.

What is claimed is:

1. A pliable conductive shield comprising a body of thinmalleable sheet metal, uniformly distributed substantially uni-planar conductive projection means secured to the bottom surface of said body in conductive contact therewith, and a layer of adhesive material on said bottom surface and being substantially flush with. said projection means for securing the shield to a metal surface with said projection means in conductive engagement with the metal surface.

2. A pliable conductive shield comprising a body of thin malleable sheet metal, a conductive grid secured to the bottom surface of said body in conductive contact therewith, and a layer of adhesive material on said bottom surface with the bottom surface of said adhesive layer substantially flush with the bottom plane of said grid for securing the shield to a metal surface with said grid in conductive engagement with the metal surface.

3. A pliable conductive shield device comprising a web of malleable metal foil, substantially uniformly distributed uni-planar malleable metal spaced projection means conductivelv secured to the bottom surface of said web, and adhesive material on said bottom surface filling the spaces defined by said projection means but being substantially flush with the bottom surface of the projection means for securing the device in covering relation to a conductive metal surface with the projection means held in conductive contact with said metal surface.

4. A pliable conductive shield comprising a web of malleable metal foil, a malleable wire mesh grid conductively secured to the bottom surface of said web and extending substantially over the area defined by said bottom surface, and adhesive material on said bottom surface in the meshes of said grid and being substantially flush with the bottom plane of the grid for securing the shield in covering relation to a metal surface with the grid in conductive contact with said metal surface.

5. An electrode shield comprising a web of malleable metal foil, a malleable wire mesh grid conductively secured to the bottom surface of said web and being distributed over the area of said bottom surface, and adhesive material in the meshes of said'grid and being substantially flush with the bottom plane of the grid for securing the shield around an electrode with the grid in conductive contact therewith.

6. In combination, a metal body exposed in a fluid medium, a conductive metal foil member covering said body, a wire mesh intermediate member secured conductively to the inner surface of said foil member and conductively engaging said body, and adhesive material carried in the meshes of said intermediate member and adhesively securing the foil member to the body, whereby said foil member is a conductive extension of said body in said medium.

7. In combination, an electrode, a web of malleable metal foil wrapped around said electrode, and a malleable electrically conductive grid interposed between the web and the electrode in conductive contact with said web and electrode, and means securing said foil to said electrode.

8. In combination, an electrode, a web of malleable metal foil wrapped around said electrode, a malleable electrically conductive grid interposed between the web and the electrode in conductive contact with said web and electrode and adhesive material in the meshes of said grid securing the web to the electrode.

9. In combination, an electrode, a web of malleable metal foil wrapped around the electrode, a layer of malleable wire screen material interposed between the web and the electrode, said layer being conductively secured to the web and being in conductive contact with the electrode, and adhesive material disposed in the meshes of said wire screen material and being in adhesive contact with the electrode, whereby to secure the web to the electrode with the web forming a conductive extension of the electrode.

M. In an enclosure containing a fluid medium, a metal body projecting into the enclosure and being normally subjected to depositions of material from the medium, and detachable shield means on the body to receive such depositions of material, said shield means comprising a conductive malleable metal foil member covering a substantial portion of the surface area of said body, malleable metal grid means interposed between the foil member and the surface area covered thereby and being in conductive relationship between the foil member and said surface area, and adhesive material carried in the spaces defined by said grid means and adhesively securing the foil member to said surface area, whereby said foil member defines a conductive extension of said metal body in said fluid medium.

11. In an enclosure containing a fluid medium, a metal body projecting into the enclosure and being normally subjected to depositions of material from the medium, and detachable shield means on the body to receive such depositions of material, said shield means comprising a conductive malleable metal foil member covering a substantial portion of the surface area of said body, malleable metal grid means interposed between the foil member and the surface area covered thereby and being in conductive contact with said member and said surface area, and adhesive material carried in the spaces defined by said grid means and adhesively securing the foil memher to said surface area, whereby said foil member defines a conductive extension of said metal body in said fluid medium, said foil member having a free portion ex- I tending outwardly from the metal body and serving as a tab means for stripping the shield member from the body.

References Cited by the Examiner UNITED STATES PATENTS 2,808,352 10/1957 Coleman et a1.

LARAMIE E. ASKIN, Primary Examiner.

Claims (1)

1. A PLIABLE CONDUCTIVE SHIELD COMPRISING A BODY OF THIN MALLEABLE SHEET METAL, UNIFORMLY DISTRIBUTED SUBSTANTIALLY UNI-PLANAR CONDUCTIVE PROJECTION MEANS SECURED TO THE BOTTOM SURFACE OF SAID BODY IN CONDUCTIVE CONTACT THEREWITH, AND A LAYER OF ADHESIVE MATERIAL ON SAID BOTTOM SURFACE AND BEING SUBSTANTIALLY FLUSH WITH SAID PROJECTION MEANS FOR SECURING THE SHIELD TO A METAL SURFACE WITH SAID PROJECTION MEANS IN CONDUCTIVE ENGAGEMENT WITH THE METAL SURFACE.

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