Abstract:
An air filter has a mechanism for preventing blow-by around a perimeter of the filter. The air filter has two rigid frames surrounding a filter and at least one of the rigid frames comprises a brush seal track with a brush seal therein.

Description:
BACKGROUND 
       [0001]    Polarized media and other active field air cleaners are typically designed so that two framed screens are hinged and latched together. The frames are typically made of a rigid material such as a rolled or extruded aluminum rail. Hinges and latches are attached to these. 
         [0002]    There are issues, however, with this approach to air cleaners that slide into a track. First, the tracks themselves are made of metal and are not consistently fabricated unit to unit. Therefore to ensure that the frames will slide into the tracks, the frames are often undersized and will not seal tightly. This results in blow-by of air around the air cleaner that is not cleaned, degrading system performance. Second, this is exacerbated by the fact that if the latches and hinges protrude from the surface of the frame, the frame must be undersized to accommodate that dimension, ie the frame will have to be even smaller—allowing for more blow-by. 
         [0003]    Third, the tracks themselves are often attached with screw or rivets and the latches and hinges of the air cleaner typically protrude from the surface of the frame and can catch on the rivets and screws, making service and installation difficult. 
         [0004]    Fourth, in many cases, the construction of the track and overall duct system is such that there is ductwork or other sheet metal on either side of the track opening. Here, the filter can slide into the track and be flush or recessed relative to the surrounding structures. Therefore, once the filter is installed in the track, there is no surface by which one can easily get a hold on the air cleaner when it needs to be pulled out and removed for service and media replacement. This makes it harder to remove an air cleaner from the track and can lead to damage of the air cleaner when tools such as pliers or screwdrivers are used to remove the filter. 
       SUMMARY OF THE EMBODIMENTS 
       [0005]    An air filter has a mechanism for preventing blow-by around a perimeter of the filter. The air filter has two rigid frames surrounding a filter and at least one of the rigid frames comprises a brush seal track with a brush seal therein. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is an isometric view of a filter and frame. 
           [0007]      FIGS. 2   a - 2   c  show different views of a frame. 
           [0008]      FIG. 3  shows an alternate embodiment of a frame. 
           [0009]      FIGS. 4   a - 4   c  show embodiments of a latch on a frame. 
           [0010]      FIG. 5  shows an alternate embodiment of a frame. 
           [0011]      FIG. 6  shows another alternate embodiment of a frame. 
           [0012]      FIGS. 7   a - 7   c  show embodiments of a frame with seals therein. 
           [0013]      FIGS. 8 and 9  show handle embodiments mounted on a frame. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0014]    The following filter embodiments address the issues described above.  FIG. 1  shows an air cleaner  80  for insertion into an air handling unit (not shown). The air cleaner  80  includes a frame structure  90  comprising two frames  100  that hold a filter material between them and behind a mesh screen, within the area shown by reference number  110 . The frame  100  may include a brush seal track  120  with a brush seal  122  therein that has been added to frame, corners  140 , a handle  160 , an extruded “live” hinge  200  (see  FIG. 3 ), and a latch  300 . The track  120  may accommodate a range of brush sizes, as shown in  FIG. 7 . to allow for custom fitting of the air cleaner  80  into the available filter track. The latch  200  has been designed to fit within the frame dimensions as shown in  FIGS. 4   a - 4   c.  The pull or handle  160  provides an end user with a handhold for air cleaner  80  removal and service. 
         [0015]    Looking at the brush seal  122  that is shown in more detail in  FIGS. 2   a - 2   d ,  4  (within hinge  200 ), and  7   a - 7   c,  the brush seal  122  has an engagement portion  122  and sealing portion  126 . The seal&#39;s engagement portion  124  is contained within the brush seal track  120  that has tabs  121  that wrap around the engagement portion  124  and hold the seal  120  to the frame  100 . A similar track with tabs  121  may be used in a corner piece  130  (often but not always made from plastic) on the frame  100  to minimize leakage as shown in  FIG. 2   b . As shown in  FIGS. 2   c  and  2   d , the track can be a dovetail track  121   a  or slot track  121   b.    
         [0016]    The frames  100  are joined together in parallel using a hinge element  200 . The hinge element  200 , which may be flexible along a flexing portion  226 , has at least two tracks  220 , with tabs  221  that contain a seal  122 . The hinge element  200  includes hinge element engagement portions  224  that engage within the frame track  120  and tabs  121 . The hinge element  200  with the seal  122  capability provides better sealing around the hinge  200  in use. 
         [0017]    As shown in  FIGS. 4   a - 4   c,  another feature of the frame  100  along a rail  102  (this would likely be located at a rail opposite the location of the hinge  200  is a latching element  300 ,  320 , or  340 . Each of the 3 latching elements  300 ,  320 , and  340  serve the same purpose of securing the frames  100   a  and  100   b  to one another, but with a low profile that does not extend beyond the top of the rail  102 , and other low profile latches are possible beyond these 3 shown herein. The thumb latch  300  has a thumb portion  302  that helps an end user move the latch  300  and a catch portion  304  that secures a pin  306  to secure the first frame  100   a  to the second frame  100   b.  In another version, the latch  320  includes a screw  322  engaged to a threaded tab  324 . When tightened, the screw  322  engages a filter mating tab  326  to secure the frame  100   a  to the frame  100   b . In another version, the latch  340  includes mating magnets  342 ,  344 , one attached to the frame  100   a  and the other to the frame  100   b  to secure them together. It should be appreciated that in each of the embodiments in  FIGS. 4   a - 4   c,  a latching element on each frame comes together with a latching element on the other frame to join the frames  100   a,    100   b  together. This allows the frames  100   a,    100   b  to be separated in a clamshell way using the hinge element  200 , such that the frames  100   a,    100   b  can be opened for filter material insertion and maintenance. 
         [0018]    As shown in  FIG. 5 , two frames  100  may also be joined together in addition to the hinge element  200  and latch elements or in their place, using magnetic strips  500  attached to the frames  100 . The strips  500  would engage one another so that the frames  100  and filters  110  therein would be side-by-side. 
         [0019]    As shown in  FIG. 6 , an improved frame  100  may comprise a thicker extrusion (aluminum with a thickness greater than 0.24″ or steel) that may have a spline  600  and/or steel mesh screen  602  in place of a more lightweight screen. Such a reinforcement helps to resist lateral forces through the air filter  80 . Other forces, especial torsional diagonal forces may be resisted by inserting a steel mesh  602  that may be frictionally held in place with a spline  600 . These reinforcing elements may be desirable in higher stress environments or just to minimize bending and breakage in normal environments. 
         [0020]      FIGS. 8 and 9  show variations of a handle  160 ,  180  installed along the frame track  120 .  FIG. 8  shows a D-ring handle  160  attached to the frame  100  using a screw  162 . The D-ring  164  rotates about an axis through a conduit  166  when being used.  FIG. 8  shows a pull handle  180  (in two views) engaged to the frame in the track  120 . Both handles allow for easier movement of the frame  100 .