Abstract:
Embodiments of the invention generally provide a frame assembly having an integral holding frame/clamp. The frame assembly is typically mounted in a housing of an air handler or other air moving conduit. The holding frame/clamp is coupled to the frame assembly by a hinge. The holding frame/lamp is configured to retain a prefilter. When the holding frame/clamp is to a closed position, the holding frame/clamp urges a final filter sealingly against the frame assembly. The clamp holding frame/clamp is maintained in the closed position by a latch. The latch facilitates removal and replacement of the final ter rapidly without tools, thereby substantially reducing the expense associated with filter change out.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims benefit from U.S. Provisional Patent Application Ser. No. 60/765,459, filed on Feb. 3, 2006, which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     Filter holding frames, such as Type 8 holding frames, may be used with a variety of fasteners, which will allow the installation of various combinations of ASHRAE prefiltration and final filtration into a ventilation system. Type 8 holding frames are available from Camfil Farr, Inc., of Riverdale, N.J. The installation may include any, or combinations of the following:
         Any 1″ deep panel or pleated filter   Any 2″ deep panel or pleated filter   Any 4″ deep panel or pleated filter   Any 6″ or 12″ deep rigid filter   Any headered style rigid or pocket filter       

     In contrast, high efficiency filters, such as 95% DOP filter, HEPA filters and higher efficiency filters, require the use of some type of mechanical clamping mechanism to effectively seal the filter to the filter housing and ensure that any bypass or leakage around that seal is no greater than the maximum penetration of the filter. For example, a HEPA filter with an efficiency of 99.97% has a maximum allowable penetration of 0.03%. Thus, the filter must seal to the filter housing effectively enough so that only a maximum of 0.03% leakage occurs between the filter and the holding frame. 
     The need to have clamping devices to seal high efficiency filters and various types of fasteners to secure and hold ASHRAE filters results in a very time consuming and costly process when filters must be removed and/or installed. This is particularly true on large filtration systems where dozens, if not hundreds, of filters must be removed and replaced on a regular basis. The use of wrenches, ratchets, or other types of tools is often required in order to loosen nuts, bolts, or other fasteners in order to remove the filters from the holding frames or to loosen the filter clamping mechanisms. 
     Thus, there is a need for a filter holding frame with a clamping mechanism that does not require the use of tools to operate, that can be used to effectively secure and seal high efficiency filters in a filter housing, while at the same time effectively hold and seal prefilters and lower efficiency filters in the holding frame. 
     SUMMARY OF THE INVENTION 
     Embodiments of the invention generally provide a frame assembly having an integral holding frame/clamp. The frame assembly is typically mounted in a housing of an air handler or other air moving conduit. The holding frame/clamp is coupled to the frame assembly by a hinge. The holding frame/clamp is configured to retain a prefilter. When the holding frame/clamp is rotated to a closed position, the holding frame/clamp urges a final filter sealingly against the frame assembly. The clamp holding frame/clamp is maintained in the closed position by a latch. The latch facilitates removal and replacement of the final filter rapidly without tools, thereby substantially reducing the expense associated with filter change out. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       A more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof that are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. 
         FIG. 1  is a schematic sectional view of one embodiment of an air handler having a frame assembly with an integral holding frame/clamp of the present invention. 
         FIGS. 2A-B  depict alternative embodiments of a frame assembly respectively having a seal for sealing a filter to the frame assembly. 
         FIG. 3  is a perspective view of a filter housing having a holding frame assembly and a filter installed therein. 
         FIG. 4  is a perspective view of one embodiment of a hinge. 
         FIG. 5  depicts one embodiment of the holding frame/clamp rotated away from a filter disposed in the holding frame assembly. 
         FIG. 6  is a perspective view of the holding frame/clamp slightly ajar from the closed position. 
         FIG. 7  depicts a perspective view of one embodiment of a latching bracket. 
         FIG. 8  depicts one embodiment of a latch. 
         FIG. 9  depicts the latch of  FIG. 8  having a plunger in a retracted position. 
         FIG. 10  depicts one embodiment of a latch engaged with a latching bracket. 
         FIG. 11  depicts a partial perspective view of a final filter retained to a frame assembly by a holding frame/clamp. 
     
    
    
     To facilitate understanding, identical reference numerals have been used, wherever possible, to designate identical elements that are common to the figures. 
     DETAILED DESCRIPTION 
       FIG. 1  depicts a schematic sectional view of an air handler  100  having a filter frame assembly  102  sealing disposed therein. Although the filter frame assembly  102  is shown mounted inside the air handler  100 , it is contemplated that the inventive filter frame assembly  102  may be utilized advantageously in any other air moving conduit. 
     The air handler  100  generally includes a housing  104  which contains a blower  106  and a filter bank  108  having one or more filters  110  one of which is a final filter  300 . The blower  106  draws air into the housing  104  through a grate  112  and through the filter bank  108  to a conduit  114 . The filtered air leaving the air handler  100  through the conduit  114  is typically routed to a facility or other location. Although the blower  106  is shown on the downstream side of the frame assembly  102 , the blower  106  may alternatively be located in an upstream location. 
     The frame assembly  102  is sealingly coupled to the housing assembly  104  and supports the one or more air filters  110  comprising the filter bank  108 . The frame assembly  102  may be sealed to the housing  104  by welding, caulking, gaskets, or other suitable methods. Generally, the frame assembly  102  includes a support  116 , such as a plate, track, or ledge for holding the air filter  110  in a predefined position relative to an air flow aperture  118  formed in the frame assembly  102 . The flow aperture  118  may be in the wall of the frame assembly  102 , or by securing one or more single filter frames into a larger frame assembly  102 , which may be fastened and sealed together. In the embodiment depicted in  FIG. 1 , the frame assembly  102  includes a plurality of aperture rows  120 , for example, for supporting an upper and lower tier of filters  110 . Further, the housing may include an access door  122 .  FIG. 3  illustrates a final filter  300  in the upper tier of the frame assembly  102  resting on a support  302 . 
     Referring additionally now to  FIGS. 2A and 2B , a holding frame/clamp  200  is coupled to a downstream wall  201  of the frame assembly  102  by a hinge  202 . The holding frame/clamp  200  may include a gasket  204  on the downstream side which urges the final filter  300  against a gasket or a knife edge  205 , shown schematically, of the downstream wall  201  of the frame assembly  102 , such that the final filter  300  is sealingly coupled to the frame assembly  102 . The gasket or knife edge  205  may be a gel seal, wherein the knife edge  205  contacts a gel to form a fluid seal. Although the final filter  300  is generally a 95% DOP, HEPA, or other high efficiency filter, filters having other efficiencies or configurations may be utilized as required. 
     A gasket  206  may additionally be provided on the upstream side of the holding frame/clamp  200 . The gasket  206  is utilized to seal a prefilter  208 , retained to the holding frame/clamp  200  by a spring clip  210  or other device such as a wire clip, to the holding frame/clamp  200 . The prefilter  208  is typically an American Society of Heating Refrigeration and Air Conditioning (ASHREA) filter, or other suitable first stage filter. 
       FIG. 3  illustrates the filter housing  104  with the final filter  300  installed in the upper tier of the frame assembly  102 . 
       FIG. 4  illustrates a view of the hinge  202 . As shown, the hinge  202  pivotally couples the holding frame/clamp  200  to the frame assembly  102 . The hinge  202  may include one or more gussets  400  coupled to a hinge pin  402 . The frame assembly  102  or the housing  104  may have a permanently attached hinge retainer  404  to hold the hinge pin  402 . As shown the hinge retainer  404  has an open end  406  which allows the hinge pin  402  to be easily removed from the hinge retainer  404 , thereby removing the holding frame/clamp  200  from the frame assembly  102 . 
     Referring now to  FIGS. 5-6 , once the final filter  300  is disposed in the holding frame assembly  102 , the holding frame/clamp  200  is rotated to urge the filter  300  sealingly against the downstream wall  201  of the frame assembly  102 . The configuration of the hinges  202  is such that in order to secure the holding frame/clamp  200  in the closed position, the gasket or knife edge  205  must be sufficiently compressed to urge and/or retain the final filter  300  in a predefined position against the downstream frame wall  201 . In embodiments wherein the depth of the final filter  300  is not large enough to respectively touch the downstream wall  201  and the holding frame/clamp  200 , a hollow spacing frame, not shown, may be disposed in the frame assembly serially with the final filter  300 . 
       FIG. 6  illustrates the holding frame/clamp  200  ready to be latched in the closed position. The holding frame/clamp  200 , as shown, is touching the top of the filter  300  but is spaced away from a bottom of the filter. This allows the holding frame/clamp  200  to compress the gasket or knife edge  205  when the holding frame/clamp  200  is latched in the closed position. 
       FIGS. 7-10  depict one embodiment of a latch  800  suitable for securing the holding frame/clamp  200  in a closed position. The latch  800  is generally coupled to the holding frame/clamp  200  while one or more latching brackets  700  are coupled to the frame assembly  102  or vice versa. In embodiments which the filters  110  are vertically tiered, the upper latching brackets are staggered with the lower hinges to avoid interference. 
       FIG. 11  illustrates the one or more filters  110  installed and secured in an upper tier of the holding/clamping frame  200 . 
     In one embodiment, the latching brackets  700  extend substantially perpendicular from the upstream side of the frame assembly  102 . The distal ends of the latching brackets  700  are angled or flared  702  outward to facilitate engagement with the latch  800  coupled to the holding frame/clamp  200 . 
     In one embodiment, the latch  800  includes a spring-loaded plunger  802  which is automatically depressed when the frame/clamp  200  is rotated to the closed position. This is due to the relative position of the flared end  702  of the latching bracket  700  and the position of the latch  800  on the holding frame/clamp  200  which causes the plunger  802  to recess upon contact with the flared end  702 . Once the holding frame/clamp  200  is rotated into the closed position compressing the gasket or knife edge  205 , the plunger  802  extends and engages with a hole  706  formed through the latching bracket  700 , thereby securing the holding frame/clamp  200  in the closed position. This allows the filter  110  to be secured in the holding frame assembly  102  by merely closing the holding frame/clamp  200  and allowing the latch  800  to automatically engage the latching bracket  700 . A slide pin  804  may be provided on the latch  800  to manually retract the plunger  802  to release the latch  800  from the latching brackets  700  without tools. It is contemplated that other types of latches may be utilized, for example, over center latches, detents, spring clips, and the like. It is additionally contemplated that the latch may include a quick disconnect, such as a bayonet, quarter turn fitting, and the like. Alternatively, the latch may include a threaded knob or other fastener. 
     Since little or no tools are used to remove and secure filters  110  to the frame assembly  102 , filter replacement is rapid, efficient, and at minimal cost relative to filter exchanges in conventional systems. As a dedicated holding frame/clamp  200  secures the final filter  300  in a respective aperture  118  of the frame assembly  102 , variations between the one or more filters  110  and holding frames  200  are accounted for on a filter-by-filter basis to ensure proper sealing between the final filter  300  and the holding frame assembly  200 . Moreover, the frame assembly  102 , with integral holding frame/clamp  200 , allows the final filter  300  to be exchanged without removal of the prefilter from the holding frame/clamp  200 . 
     While the foregoing is directed to embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.