Abstract:
An air filter cabinet designed for a relatively large electronic air filter cells is adapted to receive and position a relatively smaller filter element without an associated loose fitting relationship and air leakage. A plurality of S-shaped adaptor elements are each removably interconnected to a respective guide rail in the cabinet to reduce the size of a cavity so as to accommodate the smaller filter element and secure it in a fixed position while preventing air leakage therearound.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to our air filters and, more particularly, to a housing for containing our air filters. 
     Within residential heating and cooling systems of the forced air type, it has become common to filter the air that passes through the system. The most common types of filters are simple mechanical filters for removing particulate from the air stream as it flows through a mesh. A chemical filtration capability can also be added by the insertion of certain materials such as carbon, to remove certain undesirable chemicals. Finally, an electric air cleaner structure may be provided wherein electrically charged elements are provided in the air flow stream to filter particulates from the air stream. 
     Typically, an air cleaner for residential use is installed in association with a furnace having a fan that circulates the heated or cooled air through the duct system. However, it may be placed at any location within the air flow system that is easily accessible for purposes of replacement or cleaning of the filter. That is, a filter is normally removably disposed within a housing, such that they can be periodically removed for cleaning or be replaced by a new filter element. 
     Inasmuch as the electronic filters are the most expensive types, it has become common for contractors to provide space for a standard sized housing according to the various types and brands of electronic air cleaners. Further, since it is desirable to remove the coarser particulates from the air stream with the use of a prefilter upstream of the electronic air cleaner, the housings are commonly designed with this additional space provided. Also, with the anticipation that a chemical filter may be desirably used in combination with the electronic air cleaner, a space is preferably provided on the downstream side of the housing in order to accommodate such a chemical filter. 
     The typical mechanical or cartridge filter is generally smaller in thickness and height than the insertable cells of an electronic air cleaner. Accordingly, if a homeowner wishes to simply use a mechanical air filter, in the standard electronic filter housing the mechanical filter will be prone to movement within the housing, and may result in leakage of airflow around the filter. 
     It is therefore an object of the present invention to provide an improved housing arrangement for a mechanical air filter element. 
     Another object of the present invention is the provision for using a standard electronic filter housing for a smaller mechanical filter element. 
     Yet another object of the present invention is the provision for a housing that will adequately support a mechanical air filter element with minium air leakage. 
     Still another object of the present invention is the provision for a mechanical air filter housing which is economical to manufacture and effective and efficient in use. 
     These objects and other features and advantages become more readily apparent upon reference to the following description when taken in conjunction with the appended drawings. 
     SUMMARY OF THE INVENTION 
     Briefly, in accordance with one aspect of the invention, a plurality of adaptor brackets are attached to respective guide rails of an electronic filter housing, such that a smaller thickness mechanical filter may be placed and securely held in the relatively larger housing. 
     By yet another aspect of the invention, the brackets are S-shaped with each one having an upstanding leg being attached to a vertically aligned guide rail which normally serves to slideably receive an electronic air filter element. 
     By yet another aspect of the invention, the S-shaped element is secured to the guide rail by a frictional engagement wherein a pair of parallel bracket legs straddle the guide rail to affix the bracket. 
     By still another aspect of the invention one of the parallel bracket legs has a pair of longitudinally extending ribs for engaging the rail. 
     By yet another aspect of the invention, one leg of the bracket is longer than the other so as to extend the vertical space thereof. 
     In the drawings as hereinafter described, a preferred embodiment is depicted; however, various other modifications and alternate constructions can be made thereto without departing from the true sprit and scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a conventional electronic air filter housing with the filter elements installed therein. 
         FIG. 2  is a perspective view of such a housing with an mechanical filter element disposed in a partially installed position. 
         FIG. 3  is a perspective view of an adaptor in accordance with a preferred embodiment of the invention. 
         FIG. 4  is a perspective view of a housing with the adaptors of the present invention incorporated therein. 
         FIGS. 5 and 5A  are end views of a mechanical filter as installed in a housing with adaptors incorporated therein. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to  FIG. 1  there is shown a typical electronic air filter assembly  11  of the type normally placed in the air flow stream flowing to a space to be heated and/or cooled. A duct mounted cabinet  12  is adapted to receive a pair of electronic cells  13  and  14  in end-to-end relationship as shown. The cells  13  and  14  are inserted into an open front end  16  which is then closed by an end cover  17 . A power tray assembly  18  is mounted on top of the cabinet  12  and is adapted to provide electrical power to each of the cells  13  and  14  for purposes of providing high voltage electrical power to the individual ionizer wires therein. 
     The air to be cleaned is circulated through the air filter assembly  11  in the direction indicated by the arrows. A mechanical air filter  19  may be placed upstream of the cells  13  and  14  as shown in order to filter out the larger particles in the air stream. The mechanical air filter  19  is normally of the type which can be removed, cleaned and re-installed from time to time, but it may also be of the disposable type which is periodically replaced when dirty. The electronic cells  13  and  14  are adapted to be periodically removed, cleaned and re-installed. 
     Referring now to  FIG. 2 , the cabinet  12  is shown to include top and bottom side members  21  and  22  as well as a back side member  23 . Attached to the bottom side member  22  is a pair of U-shaped guide rails  24  and  26  that are spaced apart in parallel relationship as shown. These guide rails are preferably permanently attached to the bottom side member  22  by welding or the like. Similarly, attached to the inner side of the top side member  21  are a pair of guide rails  27  and  28 . The guide rails  24 ,  26 ,  27  and  28  collectively define the four corners of a cavity  29  for receiving the cells  13  and  14  therein. That is, the distance between the guide rails  24  and  26 , and that between the guide rails  27  and  28  is slightly greater than the thickness or depth of the cells  13  and  14 , such that the cells  13  and  14  fit snugly between the respective guide rail pairs. 
     The length of the guide rails do not extend the full length of the cabinet. The reason of this is that they are primarily for positioning and holding the cells  13  and  14  in place and therefore are not needed across the full length of the top and bottom sides  21  and  22 . Further, at the front end, through which the cells are installed, it is preferable to leave some clearance between the end of the cabinet and the ends of the guide rails in order to accommodate certain portions of the door  17  that may project into the cabinet  12 . 
     The space defined by the guide rails themselves (i.e., within the U-shaped members), are used to contain the mechanical or chemical filters. That is, the mechanical air filter  19  can be slid into the U-shaped openings of the guide rails  26  and  28 . Similarly, a downstream filter can be slid into the U-shaped openings of the guide rails  24  and  27 . 
     The electronic air filter assembly  11  as described hereinabove is of the standard size in the industry and is therefore desirable for use even when the cabinet  12  is used for containing disposable mechanical air filter cartridges. Such a disposable mechanical air filter cartridge is shown at  31  in FIG.  4 . The filter element  31 , which has a height h, width w and a depth d, is generally smaller in two dimensions then the pair of electronic filter cells  13  and  14 . The filter cartridge is substantially twice as wide (i.e. in the w dimension) than the relatively heavy single cells  13  and  14  since, primarily for handling purposes, the cells  13  and  14  are preferably kept to a relatively narrow dimension. However, the thickness or depth d is less than that of the cells  13  and  14 , and therefore less than the distance between the guide rails  24  and  26 . Similarly, the height h is less than that of the cells  13  and  14 . Accordingly, if the filter element  31  is installed directly into the cabinet  12 , it would fit very loosely in the cavity  29  and would therefore not be precisely located therein so as to allow the movement of the filter within the cavity  29 . Further, the flow of air would tend to pass around the edges of the filter  31  and therefore not be filtered. 
     In order to solve this problem the present invention includes the use of a plurality of adaptors as shown at  32  in FIG.  3 . The adaptor bracket  32  comprises a pair of integral, back-to-back U-shaped elements that are formed in a S-shape by the parallel legs  33 ,  34  and  36 . The adaptor bracket  32  is sized and configured such that when one is installed on each of the four guide rails as described hereinabove, the size of the cavity  29  is reduced to substantially the size of the mechanical air filter  31 . 
     The adaptor bracket  32  is preferably of a relatively stiff but somewhat flexible material such as plastic or the like. It is designed to be selectively installed and/or removed by simply clamping or unclamping from the installed position. This is facilitated by a pair of ribs  37  and  38  on the element  36  as shown in FIG.  3 . The ribs  37  and  38  run the length of the element  36  and are indented to provide stiffness to the element  36  and also a gripping action when placed in the installed position as will be described hereinafter. The thickness of the element  32  is designed to coincide with the difference in thickness between the electronic cell units and the mechanical filter elements  31 . That is, the distance between the outer side of element  33  and the outer side of element  34  is designed to reduce the size of the cavity  29  to substantially the thickness d of the filter element  31  as will be more fully described hereinafter. 
     The length of the adaptor element  32  is substantially equal to the width w of the air filter element  31 . In this regard, it should be noted that this length is greater than that of the guide rails which, as mentioned above, do not extend the full width of the cabinet  12 . 
     Referring now to  FIGS. 4 ,  5  and  5 A, the mechanical disposable filter  31  is shown in its respective about-to-be installed and its installed positions within the cabinet  12 , with the adaptor brackets  32  being installed in the four corners of the cavity  29  to accommodate the difference in sizes as discussed hereinabove. The adaptor brackets  32  are installed by sliding the U-shaped portion formed by elements  34  and  36  over the inner leg of the U-shaped guide rail as shown in  FIG. 5   a . The ribs  37  and  38  act to frictionally engage the inner side of the U-shaped guide rail. The element  33  projects vertically to a greater extent then the elements  34  and  36  so as to reduce the vertical height of the cavity  29  so that the smaller filter element  31  can be used without a gap between the filter and the cabinet  12 . 
     As will be seen in  FIG. 5 , the pair of adaptors  32  at the lower end of the cabinet  12  substantially fill up the space between the guide rails  24  and  26  and the sides of the filter element  31 . Similarly, the pair of adaptor elements  32  at the top of the cabinet  12  perform the same function. In combination, the four adaptor elements  32  precisely locate the filter element  31  in the center of the cabinet  12  and hold it in that fixed position. Further, they prevent the flow of air that otherwise would occur between the filter  31  and the cabinet  12 . 
     While the present invention has been described with reference to a particular preferred embodiment and with the accompanying drawings, it will be understood that those skilled in the art that the invention is not limited to the preferred embodiment and that various modifications and the like could be made to the two without departing from scope of the invention as defined in the following claims.