Abstract:
A rigid support is disposed in a filtration media element. A first gas-permeable filtration media layer is disposed in an overlapping orientation with a second gas-permeable filtration media layer. The first and second layers define a void in which the support is disposed. The first layer is attached to the second layer near opposing edges of the first and second layers and at an attachment termination point substantially centrally located on the filtration media element. The filtration media element has a first media end and an opposite, second media end. The support has a first support portion that extends from the first media end toward the attachment termination point. The support has second and third support portions that extend from the first support portion toward the second media end with a gap between the second and third support portions in which the attachment termination point is disposed.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 62/087,335 filed Dec. 4, 2014. The prior application is hereby incorporated by reference. 
     
    
     STATEMENT REGARDING FEDERALLY-SPONSORED RESEARCH AND DEVELOPMENT 
       [0002]    (Not Applicable) 
       THE NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT 
       [0003]    (Not Applicable) 
       REFERENCE TO AN APPENDIX 
       [0004]    (Not Applicable) 
       BACKGROUND OF THE INVENTION 
       [0005]    The invention relates generally to air filtration devices, and more particularly to air filters with filtration media surrounding an internal rigid support that can be removed from the used filtration media. 
         [0006]    It is well known to construct an air filter  8  from filtration media  14  and a rigid support  10  mounted internally within the media. The rigid support  10  is commonly thick steel wire formed in a rectangularly-shaped support  10  as shown in  FIG. 2 , with the filtration media  14  surrounding the support  10  as shown in the cutaway of  FIG. 1 . The filtration media  14  is commonly a porous, polymer, non-woven batt material, formed in a sheet-like layer. Two sheets of this material are formed into a sleeve shape by stitching  12 , welding or otherwise connecting the lateral edges of two layers of filtration media that are placed with their major surfaces against one another. The area located inside of the stitches  12  is devoid of stitching so that the media layers can be separated, such as for removing the support  10 . The rigid support  10  is inserted into the opening in the sleeve-shaped media  14  and the open ends of the sleeve-shaped media  14  are then welded or stitched together to retain the rigid support  10  as shown in  FIG. 1 . 
         [0007]    As shown in  FIG. 3 , the filter media  14  is also commonly welded or stitched at reinforcement points  16 , inside of the perimeter of the filter  8  to prevent the portions of the layers of media  14  that are not stitched together from moving apart, or from moving cyclically toward and away from each other, when air is forced through. This configuration provides a filter with good rigidity and good filtration characteristics, but with poor ability to remove the support  10  for recycling or disposal. In order for the components of the filter  8  shown in  FIGS. 1-3  to be separated, the stitching  12  and reinforcement points  16  must all be cut or removed so that the support  10  can be separated from the media  14 . However, when this is attempted with a used filter, a substantial volume of filtered particles in the media is often returned to the environment due to mechanical agitation of the filter media, which is not acceptable. 
       BRIEF SUMMARY OF THE INVENTION 
       [0008]    A gas filter disclosed herein may be formed by inserting a support into a sleeve made of a filtration media element. The filtration media element includes a first gas-permeable layer disposed in an overlapping orientation with a second gas-permeable layer. The first and second layers define a void between a major surface of the first layer and a facing major surface of the second layer. The first layer is attached to the second layer at least near opposing edges of the first and second layers and at an attachment termination point that is substantially centrally located on the filtration media element. The filtration media element has a first media end and an opposite, second media end. The support has a first support portion that extends from the first media end toward the attachment termination point. The support also has second and third support portions that extend from the first support portion toward the second media end with a gap between the second and third support portions in which the attachment termination point is disposed. 
         [0009]    The filter is used in a conventional fashion by inserting it across a closed path air stream, such as in ductwork, typically upstream of a furnace or other HVAC air-moving unit. By positioning the attachment termination point substantially in the central region of the filtration media element, the first and second layers are supported where they are far from the peripheral edges. Thus, segments of the support extend immediately around the termination point so that the central region of the sleeve is supported near its weakest point. 
         [0010]    Once the filter has reached the end of its useful life, it is removed from a filter-retaining structure and the support is pulled out of the used media element in the direction opposite that of insertion. This prevents the particulate contained in the media from being substantially disturbed, thereby preventing any substantial amount of the particulate from being returned to the environment. It will be appreciated that by fastening the media layers together near the central region of the media sleeve, the layers are supported to avoid separating during use. Further, the support may be removed from the filtration media element after use by simply sliding the support out of the open end of the filtration media element. Thus, little to no mechanical agitation is required to separate the support from the media for disposal. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0011]      FIG. 1  is a side view in section illustrating a prior art filter. 
           [0012]      FIG. 2  is a side view illustrating a prior art filter support. 
           [0013]      FIG. 3  is a side view illustrating the prior art filter of  FIG. 1 . 
           [0014]      FIG. 4  is a side view illustrating a support used in a filter embodying the present invention. 
           [0015]      FIG. 5  is a side view illustrating a filter media sleeve embodying the present invention. 
           [0016]      FIG. 6  is an end view illustrating the filter media sleeve of  FIG. 5 . 
           [0017]      FIG. 7  is a side view illustrating a filter embodying the present invention. 
       
    
    
       [0018]    In describing the preferred embodiment of the invention which is illustrated in the drawings, specific terminology will be resorted to for the sake of clarity. However, it is not intended that the invention be limited to the specific term so selected and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar purpose. For example, the word connected or terms similar thereto are often used. They are not limited to direct connection, but include connection through other elements where such connection is recognized as being equivalent by those skilled in the art. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0019]    U.S. Provisional Application No. 62/087,335 filed Dec. 4, 2014 is incorporated in this application herein by reference. 
         [0020]    A support  100  and sleeve  120  are disclosed herein and are described in more detail below with reference to  FIGS. 4 to 7 . The support  100  is shown in  FIG. 4  having a first support portion  102 , a second support portion  104  and a third support portion  106 . The second and third portions  104  and  106  extend from the first portion  102  with a gap  108  formed therebetween. The combination of the first, second and third portions  102 - 106  may provide a generally U-shaped, substantially planar structure with a base that is formed by the first portion  102 , and two legs that are formed by the second and third portions  104  and  106 . The gap  108  is formed between the second and third portions. 
         [0021]    In a preferred embodiment, the first portion  102  is formed of wire segments  102   a ,  102   b ,  102   c  and  102   d . The wire of the support  100 , and of all segments of all portions thereof, is preferably about 9 gauge steel, but may be in a range from about 8 gauge to about 11 gauge. All wire segments of the support  100  are disposed in substantially the same plane, which results in a substantially planar support  100 . Such a support, while not precisely planar, may be placed on a planar surface, such as a table, with most or all components of the support  100  contacting the planar surface, or disposed away from the planar surface a few percent of the thickness of the wire segments. Of course, different materials would allow or demand larger or smaller diameters, as will become apparent to a person of ordinary skill. 
         [0022]    The second portion  104  is formed of wire segments  104   a ,  104   b ,  104   c  and a portion of the wire segment  102   d . The third portion  106  is formed of wire segments  106   a ,  106   b ,  106   c  and a different portion of wire segment  102   d  than forms part of the second portion  104 . The gap  108  is formed between wire segments  104   c  and  106   c  and the segment  102   d ′, which does not form any segment of the second or third portions  104  and  106 . The gap  108  is in the range of a few percent to about fifty percent, and preferably about ten to twenty percent, of the width of the filter  108 . For the filter  108 , which is about 20 inches wide and about 30 inches long, the gap  108  may be two to six inches wide, but could be any size that permits the filter  130  to operate as described herein. The length of the gap is about one-half the length of the support  100 , and may be about one-third to about two-thirds the length of the support  100 . In all cases, the gap  108  extends to a location that is substantially central to the support  100 . A substantially central location in the support  100  is within the central fifty percent of the area occupied by the support  100 . 
         [0023]    The sleeve  120 , shown in  FIGS. 5 and 6  prior to insertion of the support  100 , is made of two or more media layers  122  and  124  in contact with one another on at least their adjacent major surfaces due to stitching  126 , welding or other conventional means of attachment between the two media layers  122  and  124 . The media is preferably non-woven, porous polyester, but could be any type of non-woven media. The preferred range of thickness is 0.5 to one inch for each layer, which would be 1-2 inches for the entire combination of the layers  122  and  124  when they are identical, but any thickness between about one-quarter inch to about three inches is acceptable. Also, the different layers  122  and  124  need not be made of the same material, nor must they be the same thickness. It is contemplated that the layers  122  and  124  may be made of different materials and different thicknesses. 
         [0024]    The stitching lines  126   a  and  126   b  are shown in  FIGS. 5 and 7  and are formed by sewing along both sides of the sleeve  120 . The similar stitching line  126   c  is formed at one end of the sleeve  120 . The similar stitching leg  126   d  extends from the line  126   c  into the central area of the sleeve  120  and traces a path corresponding to about the center of the gap  108  on the support  100 . All of the stitching lines  126   a - 126   d  may be formed prior to inserting the support  100  into the sleeve  120 . The stitching lines may be formed by thread that is sewn in a conventional fashion through both layers  122  and  124  to cause the facing major faces of the layer  122  and  124  to seat against one another. The stitching lines may alternatively be formed by adhering, welding or any other known form of attachment. 
         [0025]    As shown in  FIG. 5 , the side  128  of the sleeve opposite the stitching line  126   c  is not stitched or otherwise fastened together, and this results in an end through which the support  100  can be inserted into a void in the sleeve  120  between the two media layers  122  and  124 . In a preferred process, the second and third portions  104  and  106  of the support  100  are inserted into the open end  128  of the sleeve  120  before the first portion  102  is inserted, and this order of insertion allows the second and third portions  104  and  106  to extend first into the void formed between the media layers  122  and  124 . With further insertion, the second and third portions  104  and  106  extend further into the void until the stitching leg  126   d  is disposed in the gap  108  between the second and third portions  104  and  106 . During a contemplated step of the manufacture of the filter, after the support  100  is fully inserted with the first portion  102  completely within the sleeve  120 , the side  128  may be stitched or otherwise conventionally closed along the stitching line  126   e  so that the sleeve  120  retains the support  100 . However, the end  128  may be left open and without the stitching line  126   e  and friction prevents the support  100  from coming out of the sleeve  120  during use of the filter or subsequent typical handling. 
         [0026]    The stitching line  126   d  may be formed as an extension of, and/or along, an attachment termination point  126   tp  that is located in the substantially central region of the sleeve  120 . The attachment termination point  126   tp  may be a portion of the stitching line  126   d  at the center of the sleeve  120  as shown in  FIG. 7 . Alternatively, the attachment termination point  126   tp  may be at any location that is substantially central to the sleeve  120 . A substantially central location in the sleeve  120  is within the central fifty percent of the area occupied by the sleeve  120 . The advantage of the substantially central location of the termination point  126   tp  is that the layers  122  and  124  of the filtration media are best supported by gathering the layers and placing the segments that define the gap  108  around the layers  122  and  124  in the substantially central location. The location of the termination point  126   tp  may be at about one-half the length of the sleeve  120 , and may be at between about one-third to two-thirds the length of the sleeve  120 . 
         [0027]    The filter  130  that is formed from the support  100  in the sleeve  120  is used in a conventional fashion by inserting it across a closed path air stream, such as in ductwork, typically upstream of a furnace or other HVAC air-moving unit. By positioning the attachment termination point  126   tp  substantially in the central region of the sleeve  120 , the sleeve&#39;s  120  layers  122  and  124  are supported where they are far and/or farthest from the peripheral edges where the support  100  provides rigidity to the sleeve  120 . By the segments of the support  100  extending immediately around the termination point  126   tp , the central region of the sleeve  120  is supported well near where it would otherwise be least supported in the prior art filters so that gas flowing through does not overly distort or disrupt either layer  122  or  124 . 
         [0028]    Once the filter has reached the end of its useful life, it is removed from a filter-retaining structure and the support  100  is pulled out of the used filter sleeve  120  in the direction opposite that of insertion, so that the stitching leg  126   d  slips out of the gap  108  along the length of the gap  108 . This quick removal prevents the media, and particulate contained therein, from being substantially disturbed, thereby preventing any substantial amount of the particulate from being returned to the air. Then the support  100  can be used again or recycled. Furthermore, the filtration media sleeve  120  can be discarded apart from the support  100 , or it can be recycled. 
         [0029]    It will be appreciated from the description herein that the stitching leg  126   d  fastens the media layers  122  and  124  together, even as far as the central region of the media sleeve  120 , and thereby keeps the layers  122  and  124  from separating during use sufficiently to cause the negative results of the prior art. However, because of the configuration of the sleeve  120  and the support  100 , the support  100  can be removed from the sleeve  120  after use by simply sliding the support  100  out of the open end  128  of the sleeve. Thus, little to no mechanical agitation is required to separate the support  100  from the media sleeve  120  for recycling, disposal or re-use. 
         [0030]    This detailed description in connection with the drawings is intended principally as a description of the presently preferred embodiments of the invention, and is not intended to represent the only form in which the present invention may be constructed or utilized. The description sets forth the designs, functions, means, and methods of implementing the invention in connection with the illustrated embodiments. It is to be understood, however, that the same or equivalent functions and features may be accomplished by different embodiments that are also intended to be encompassed within the spirit and scope of the invention and that various modifications may be adopted without departing from the invention or scope of the following claims.