Abstract:
A fluid filter element comprising: an embossed flat filter material which is folded so as to define a plurality of substantially adjacent walls, each wall defining a planar surface between two adjacent fold lines, said wall having an embossing comprising: a first embossing row having a centrally located elongated positive embossment and a distal embossment at each end of the positive elongated embossment, wherein at least one distal embossment is negative; and, a second embossing row spaced from and parallel to the first embossing row, the second embossing row having two elongated embossments, wherein one elongated embossment is negative and one is positive. A method regarding the making of the same.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    This invention relates to a fluid filter element and method of forming the same. 
         [0002]    Fluid filter elements are well known and are widely used in fluid filters for varying areas of use, including hydrodynamic machines and air-conditioning engineering. Their meander-shaped or zig-zag structure provides a substantially increased filter area, in relation to a fixed afflux flow cross-section. In order to fix the fold walls of such a structure relative to each and to support them with respect to each other, various different kinds of design configurations have been developed. Filters with depressions which are embossed into the flat filter material and which, when the material is folded, bear against each other and support each other are known. 
         [0003]    In the case of earlier fluid filter elements of that kind, the embossings of the fold walls were simply laid against each other when executing the folding operation and the filter element, which was finished as a kind of “fold pack” which was externally fixed by being clamped in a box or frame. While such particularly simple fluid filter elements certainly operate satisfactorily at the beginning of their period of use and in areas of use which do not involve fluctuating pressure loadings worth mentioning, critical stability problems are found to occur in relation to certain degrees of filling with deposited dust particles, or dust loading, and in particular when used in relation to fluid-dynamic machines. 
         [0004]    In order to resolve many of the above problems, U.S. Pat. No. 6,685,833 assigned to LPD technologies discloses a filter element comprising an embossed flat filter material which is folded so as to define a plurality of substantially adjacent walls, each wall having an embossing comprising a first embossing portion which extends from one side of said wall and a second embossing portion which is adjacent to said first embossing portion and which extends from the other side of said wall, and an adhesive connecting adjacent embossings of adjacent walls. The adhesive preferably has a substantially constant height. U.S. Pat. No. 6,685,833 is hereby incorporated by reference in its entirety. 
       SUMMARY OF THE DISCLOSURE 
       [0005]    The primary object of the present disclosure is to provide a filter material with embossings that eliminate a rotation point within the pleat. 
         [0006]    It is a further object of the present invention to provide a fluid filter element with an embossed flat filter material which is folded so as to define a plurality of substantially adjacent walls, each wall defining a planar surface between two adjacent fold lines, the wall having an embossing comprising: a first embossing row having a centrally located elongated positive embossment and a distal embossment at each end of the positive elongated embossment, wherein at least one distal embossment is negative; and a second embossing row spaced from and parallel to the first embossing row, the second embossing row having two elongated embossments, wherein one elongated embossment is negative and one is positive. 
         [0007]    It is a further object of the present invention to provide a method for forming a fluid filter element, comprising the steps of: providing a flat filter material; forming a plurality of substantially parallel embossings in the filter material, the embossings comprising alternating first and second embossing rows, the first embossing row having a centrally located elongated positive embossment and a distal embossment at each end of the positive elongated embossment, wherein at least one distal embossment is negative; and the second embossing row spaced from and parallel to the first embossing row, the second embossing row having two elongated embossments, wherein one elongated embossment is negative and one is positive; applying an adhesive to at least a portion of the embosssings; and folding the filter material in a zig-zag pattern so as to define walls of the filter material, each wall having the alternating first and second embossing rows, wherein the adhesive bonds the embossings of adjacent walls together. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    A detailed description of preferred embodiments of the present invention follows, with reference to the attached drawings, wherein: 
           [0009]      FIG. 1  illustratively depicts a side view of a filter material and embossed in accordance with U.S. Pat. No. 6,685,833; 
           [0010]      FIG. 2  illustratively depicts a side view of a filter material embossed with an intermediate embossment at the rotation point within the pleat; 
           [0011]      FIG. 2 a    illustratively depicts a top view of the filter material of  FIG. 2 ; 
           [0012]      FIG. 3  illustratively depicts a top view of the filter material and embossed in accordance with the present invention; 
           [0013]      FIGS. 4 a -4 c    illustratively depict side views of the filter material in accordance with the present invention; 
           [0014]      FIGS. 5 and 6  illustratively depict the first embossing row in a view in section in a plane parallel to the fluid flow direction and perpendicular to the plane of the filter material, illustrating an embodiment of the filter element according to the invention; 
           [0015]      FIG. 7  illustratively depicts the second embossing row in a view in section in a plane parallel to the fluid flow direction and perpendicular to the plane of filter material, illustrating an embodiment of the filter element according to the invention; 
           [0016]      FIGS. 8, 9 and 10  illustratively depict differing variations of filter material embossings; 
           [0017]      FIG. 11  illustratively depicts a top view of the filter material embossed in accordance with the present invention; 
           [0018]      FIG. 12  illustrates the accordion effect on embossed filter media; 
           [0019]      FIG. 13  illustratively depicts a top view of the filter media of the present invention with a plurality of intermediate embossings; 
           [0020]      FIG. 14  illustratively depicts a top view of the filter media of the present invention with a plurality of intermediate embossings and diagonal straight lines obtained; and 
           [0021]      FIG. 15  illustratively depicts a top view of the filter media of the present invention with glue placement on a plurality of intermediate embossings. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    This disclosure is drawn to a filter material with embossings that eliminate a rotation point within the pleat. Embossings, i.e. dimples, are formed on the filter material by any means which is well known within the art. One objective of the present invention is to reduce the pressure drop within the system by reducing the embossed surface area of the filter paper, i.e. standard intermediate embossings are removed, and by improving the aerodynamics, which keeps the pleat from deforming. 
         [0023]      FIG. 1  illustrates a wall of filter material  4  and the structure of embossings  1  formed in filter material  4  in accordance with U.S. Pat. No. 6,685,833.  FIG. 8  illustrates a side view of a folded series of the walls of  FIG. 1 .  FIG. 1  shows flat material  4  provided with a series of embossings  1  which would be arranged in parallel rows wherein each embossing  1  is substantially planar and has a first embossing portion extending from one side of material  4  and a second embossing portion extending from the other side of material  4 . These embossings can advantageously be formed in material  4  using embossing rollers or any other apparatus suitable for forming contoured structure in material  4  as desired. During use, pressure is exerted on the filter material  4 , and the material begins to bend at rotation point  2 , which is the point where the embossing  1  passes from one side of the material  4  to the other. This results in bending of the wall having embossings  1  in the direction of arrows  5 . Rotation point  2  renders the complete pleating of the filter material  4  very difficult and also results in an unstable filter. Bending of the filter material  4  around the rotation point  2  also increases the pressure of the flow through the filter material  4  leading to a negative change in aerodynamics. 
         [0024]      FIGS. 2, 2   a  and  9  depict the introduction of an intermediate embossing  3 .  FIG. 9  illustrates a side view of a folded series of walls to illustrate the position of embossing  3 .  FIGS. 2 and 2   a  further illustrate walls  4  having embossings  1  and intermediate embossing  3  of filter material  4 . The intermediate embossing  3  is positioned in an alternating position between embossings  1 . The placement of the intermediate embossing  3 , as shown in  FIG. 2   a,  helps to avoid the undesirable characteristics described above by providing stiffness of the material  4  against bending around point  2  of the pleat. Intermediate embossing or dimple  3  stiffens the filter wall at the rotation point  2  of  FIG. 1 , but this extra embossing leads to more cost in preparation and can also reduce the effective filter area of the filter. 
         [0025]      FIG. 3  depicts a preferred orientation of embossings  10 ,  10   a,    12 ,  14 ,  14   a  in accordance with the present invention. A first embossing row,  10 ,  10   a,    12 , is shown having a centrally located elongated positive embossment  12  and distal embossment  10 ,  10   a  at each end of the positive elongated embossment  12 . At least one distal embossment  10   a  in the first embossing row is negative, that is, it extends from the sheet of the filter material in a direction opposite to that of embossments  10 ,  12 , which are considered positive. A second embossing row having two elongated embossments  14 ,  14   a  is also formed and positioned at a location laterally spaced from embossments  10 ,  12 ,  10   a.  The alternating embossment segments avoid locations where an embossment transitions between negative and positive and thereby avoids the formation of bending lines or rotation points  2  as are present in the prior art configurations. At least one elongated embossment  14   a  is negative. 
         [0026]      FIGS. 4 a  and 4 b    depict the first embossing row  1 -a and the second embossing row  1 -b, respectively. When folded into a filter structure, the first embossing row  1 -a and the second embossing row  1 -b extend parallel to each other along the material and the overlap of the various embossed segments prevents the formation of a rotation point as was formed in the material  4  of  FIG. 1 . 
         [0027]      FIGS. 5 and 6  illustrate a portion of a filter in accordance with the present invention drawn through embossings  14 ,  14   a.  The filter media  20  according to the invention is formed from a filter fleece or non-woven cloth material, typically made from glass fiber and plastic fiber components or the like. Fold edge regions  30 ,  32  define walls  40  of material  20  therebetween, and embossing portions  14  and  14   a  are advantageously defined in a single plane, and the plane of embossing portions  14  and  14   a  is preferably oriented relative to the plane of walls  40  such that when material  20  is folded into the “V” pattern shown in  FIGS. 5 and 6 , embossing portions  14  and  14   a  are substantially parallel to and equally spaced from embossing portions  14  and  14   a  of adjacent walls  40 . 
         [0028]    Hot melt adhesive threads  32  are applied on both sides in the region of the embossings  14  and  14   a.  When folded to the position shown in  FIGS. 5 and 6 , the hot melt adhesive threads  32  join together to form interconnected adhesive support portions. The mutually adjacent fold walls  40 , after the adhesive  32  has set, are respectively clamped firmly in position on both sides, by virtue of those adhesive support portions  32 , which is a substantial improvement over prior art configurations. 
         [0029]      FIG. 7  illustrates a portion of a filter in accordance with the present invention drawn through embossings  10 ,  12 ,  10   a.  The filter media  20  according to the invention is formed from a filter fleece or non-woven cloth material, typically made from glass fiber and plastic fiber components or the like. Fold edge regions  30 ,  32  define walls  40  of filter media  20  therebetween, and embossing portions  10 ,  10   a,  and  12  are advantageously defined in a single plane, and the plane of embossing portions  10 ,  10   a,  and  12  is preferably oriented relative to the plane of walls  40  such that when material  20  is folded into the “V” pattern shown in  FIG. 7 , embossing portions  10 ,  10   a,  and  12  are substantially parallel to and equally spaced from embossing portions  10 ,  10   a,  and  12  of adjacent walls  40 . 
         [0030]    Hot melt adhesive threads  34  are applied on both sides in the region of the embossing  10   a  alone and embossings  10  and  12  in conjunction. When folded to the position shown in  FIG. 7 , the hot melt adhesive threads  34  join together to form interconnected adhesive support portions. The mutually adjacent fold walls  40 , after the adhesive  34  has set, are respectively clamped firmly in position on both sides, by virtue of those adhesive support portions  34 , which is a substantial improvement over prior art configurations. 
         [0031]    An additional undesirable bending or accordion effect is illustrated in  FIG. 12 . The accordion effect contributes to the deformation of the pleat, which in turn increases the pressure drop of the filter due to the bad aerodynamics of a deformed (not a perfect V shaped) pleat. The views of  FIG. 12  illustrate this undesirable bending, which can happen when embossings spread laterally as shown. x represents the ideal configuration of a cross section of embossings. See  FIG. 10  section F 12 . As air blows through filter media  20 , pressure increases and the embossings begin to laterally spread, as illustrated by y. The pleated filter media  20  will begin to flatten and lose resistance to bending. As a result of the continuing increase in pressure, the embossings will lose form, as illustrated by x+y. When the embossings stretch and lose form the pleats also will stretch and lose form, as shown in the third view of  FIG. 12 . Intermediate embossings positioned according to the invention leave unembossed zones of material that help resist lateral spreading of the embossments, because the flat, non-embossed portion of material helps to resist the lateral spreading. Preferably, the non-embossed portions are positioned so that, taken together, they define a diagonal line (See  FIG. 11 ) of embossing free filter media which helps to prevent stretching of the pleat and embossings. 
         [0032]    The configuration of the embossings according to the invention eliminates both rotation point  2  of  FIG. 1  and the accordion effect of  FIG. 12 . The filter portions shown in  FIGS. 5-7  illustrate the orientation of the folded and glued filter media  20  as shown in  FIGS. 3 and 11 . The configuration of the dimples eliminates the horizontal rotation point  2  by creating a more desirable diagonal line  40  of unembossed portions of filter media  20 . This configuration of the unembossed to embossed portions of filter media  20  reduces the accordion effect, wherein the embossings rest upon one another to support the filter media  20  as air is forced through it. 
         [0033]    As seen in  FIG. 11 , the main intermediate embossing  12  is both above and below diagonal  40 . Intermediate embossing  12  is able to perform a double function. In order to sustain the pressure within the system, embossing  12  helps to keep the pleated filter media  20  as straight as possible and embossing  12  also helps to keep the accordion effect of material  20  to a minimum. Diagonal  40  helps to decrease the pressure flow through filter media  40  leading to less resistive aerodynamics through the system. The current design illustrated in  FIGS. 3-7  reduces the pressure drop caused by deformation of the filter walls and thereby preserving the desired flow characteristics of the filter. 
         [0034]      FIGS. 5 through 7  show fold lines  30  for material  20 , which are present along fold edges of material transverse to the embossings as shown for example in  FIGS. 3 and 11 . The preferred orientation of embossing rows  1 -a and  1 -b provide that when folded, first embossing portions  1 -a will face each other, and second embossing portions  1 -b will also face each other. Embossing rows  1 -a and  1 -b are positioned substantially parallel to each other so as to facilitate application of adhesive to embossing rows  1 -a and  1 -b at a constant flow-rate of adhesive, which provides for a constant height or amount of adhesive per length as desired in accordance with the present invention. 
         [0035]      FIG. 13  depicts the filter media of the present invention with a plurality of intermediate embossings, i.e. positive embossments, negative embossments and combinations thereof. It has been found that an increase in the number of intermediate embossings will increase the strength of the filter material and decrease the bending of the walls due to force exerted on the filter material by the air pressure. 
         [0036]      FIG. 14  depicts the diagonal straight lines of non-embossed material that may be formed on filter media comprising a plurality of intermediate embossings. As shown, the intersecting diagonal lines of non-embossed material can provide a truss-like reinforcement to the wall to prevent accordion or spreading of the embossed portions. 
         [0037]      FIG. 15  depicts the placement of the glue on filter media comprising a plurality of intermediate embossings. 
         [0038]    It is to be understood that the present disclosure is not limited to the illustrations described and shown herein, which are deemed to be merely illustrative of the best modes of carrying out the invention, and which are susceptible of modification of form, size, arrangement of parts and details of operation. The present disclosure rather is intended to encompass all such modifications which are within its spirit and scope as illustrated by the figures and defined by the claims.