Abstract:
A filter rack is spring loaded to an expanded position to help hold the filter rack at various positions and orientations within a furnace enclosure. The rack may also include a spring-loaded channel whose position adjusts to receive filters of various widths. One set of springs urge two side members of the filter rack outward, while another set of springs urge the channel inward.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to air conditioning and heating systems, and more specifically to a filter rack for holding an air filter of a furnace, heat pump, air conditioner, or other type of air handler.  
           [0003]    2. Description of Related Art  
           [0004]    Air conditioning systems typically include an air-handler that provides conditioned air to a comfort zone, such as a room or a designated area within a building. The conditioning of the air may include, but not be limited to heating, cooling, humidifying, dehumidifying, filtering, ventilating, and their various combinations. Air handlers often include a sheet metal enclosure that contains various components, such as a blower, filter, heat exchanger, controls, etc.  
           [0005]    Air handlers and their enclosures are preferably reconfigureable so they can be readily connected to a building&#39;s ductwork. Depending on the application, the building&#39;s return air duct may need to be connected to the enclosure&#39;s right side, left side, or bottom. Thus, an enclosure may include various knockout or otherwise removable panels that allow a return air opening to be created where needed.  
           [0006]    Creating such a return air opening often involves a significant amount of work and may require various tools for cutting, trimming, bending, screwing, etc. This can be especially true when the air handler&#39;s return air filter is situated right at the return air opening, which is often the case. Thus, additional work may be required to relocate filter-related hardware, such as a filter rack, which holds the filter.  
           [0007]    Once an air handler is properly configured and set up, the filter may be replaced regularly with normal maintenance. In some cases, the actual size of the replacement filter may be slightly different than that of the original filter, even though both filters may have the same nominal size. Slight differences in size may create a gap between the filter and the filter rack, which could allow return air to bypass the filter.  
           [0008]    In some cases, the size of a filter may be adjustable, as disclosed in U.S. Pat. Nos. 6,007,596; 5,492,551 and 5,312,467. However, the price of such filters may be relatively expensive, when compared to common disposable filters. Other filter assemblies may use a spring for sealing or for various other purposes, as disclosed in U.S. Pat. Nos. 2,979,159 and 5,458,667. However, such mechanisms may not close off an air gap caused by a rectangular filter whose length or width is too short. Moreover, such mechanisms may complicate the process of reconfiguring an enclosure during the initial installation of the air handler.  
         SUMMARY OF THE INVENTION  
         [0009]    To overcome the limitations of current air handler enclosures, it is an object of the invention to provide a filter rack whose side members are spring biased outward.  
           [0010]    Another object to provide a filter rack comprising a side member that is spring biased outward and a filter rail that is spring biased inward.  
           [0011]    Another object is to use a leaf spring to act between the side member and the filter rail.  
           [0012]    Another object is to use an extension spring to outwardly urge the side members of a filter rack.  
           [0013]    Yet, another object is to provide a filter rack with a movable channel for receiving filters of different widths.  
           [0014]    A further object is to provide a filter rack with sliding end members that allow the width of the filter rack to be reduced which simplifies the installation of the rack.  
           [0015]    A still further object is to connect an extension spring to a pair of sliding end members to urge the members to a greater length.  
           [0016]    Another object is to spring load a filter rack into engagement with an air handler enclosure.  
           [0017]    Another object is to provide a filter rack whose side members are movable to enable the rack to be installed within an enclosure in various orientations.  
           [0018]    These and other objects of the invention are provided by a filter assembly that includes a filter rack adapted to hold a removable filter. The rack is a generally rectangular frame with two opposite sides that are urged apart by a spring. The spring loaded sides help hold the rack within an enclosure of an air handler.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]    [0019]FIG. 1 is a cutaway view of an air handler in one configuration.  
         [0020]    [0020]FIG. 2 is a cutaway view of the air handler of FIG. 1, but with the air handler in another configuration.  
         [0021]    [0021]FIG. 3 is a front view of a filter assembly according to one embodiment of the invention, with the filter partially installed.  
         [0022]    [0022]FIG. 4 is a back view of FIG. 3.  
         [0023]    [0023]FIG. 5 is a cross-sectional view taken along line  5 - 5  of FIG. 4.  
         [0024]    [0024]FIG. 6 is a cross-sectional view taken along line  6 - 6  of FIG. 4. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0025]    An air handler  10   a,  shown in FIG. 1, includes a filter assembly  12  that can be mounted in various orientations within an enclosure  14   a.  Air handler  10   a  is schematically illustrated to represent any device for moving air  16  between an inlet  18   a  and an outlet  20  of enclosure  14   a  for the purpose of heating, ventilating, filtering, humidifying, de-humidifying, or otherwise conditioning the air of a comfort zone, room, or area within a building. Examples of air handler  10   a  include, but are not limited to, a blower  22  within an enclosure, a furnace, air conditioner, heat pump, and various combinations thereof. For the illustrated embodiment of the invention, a serviceable or disposable air filter  24  (comprising an air permeable medium  26  supported by a filter frame  28 ) filters air  16  passing through enclosure  14   a.    
         [0026]    Filter assembly  12  allows filter  24  to be installed along a side  30  or  32  of enclosure  14   a,  as shown in FIG. 1, or be installed along a bottom  34 . For example, enclosure  14   a  of air handler  10   a  can be configured to provide an air handler  10   b  with an enclosure  14   b,  as shown in FIG. 2. This can be done by removing a bottom panel  36  of enclosure  14   a  to create modified enclosure  14   b  having a return air inlet  18   b  at the bottom. The original side inlet  18   a  can then be closed off with another panel (e.g., panel  36 ), or if inlet  18   a  is already closed, it can be left that way.  
         [0027]    To allow filter assembly  12  to be readily installed in various positions within enclosure  14   a,  assembly  12  includes a generally rectangular filter rack  38  whose length  40  (or width) can expand to match various interior dimensions of enclosure  14   a.  Filter rack  12  includes two fixed length side members  42  and  44  and two adjustable length end members  46  and  48 . To make length  40  adjustable, member  46  comprises two relative sliding members  50  and  52 , and, similarly, end member  48  comprises two relative sliding members  50 ′ and  52 ′.  
         [0028]    The actual structure of filter rack  38  can vary; however, in a preferred embodiment of the invention, sliding members  50  and  52 ′ are fixed (e.g., spot welded) to side member  42 , and sliding member  50 ′ and  52  are fixed to side member  44 . Members  50  and  50 ′ are similar, and so are members  52  and  52 ′. Thus, an upper half  54  of rack  38  is similar to its lower half  56 . An edge  58  on sliding members  50  and  50 ′ is folded over a flange  60  on members  52  and  52 ′ to help keep the members in sliding engagement with each other.  
         [0029]    To help hold filter rack  38  in place within enclosure  14   a  or  14   b,  at least one spring  62  urges side members  42  and  44  apart from each other, as indicated by arrows  43 . The spring force helps hold filter rack  38  into engagement with some predetermined feature of enclosure  14   a  or  14   b.  In FIG. 1, for example, a screw  64  protruding from side member  42  engages some upper hole in enclosure  14   a,  and side member  44  is held in place by bottom panel  36 . In FIG. 2, screw  64  and another similar screw  64 ′ engage holes in sides  30  and  32  respectively.  
         [0030]    Spring  62  is preferably an extension spring (helical wire, or elastic band or cord); however, other springs such as compression springs, leaf springs, torsion springs, etc., are well within the scope of the invention. Extensions springs are preferred, as they provide relatively large travel without the need for additional structure, such as guides for preventing a compression spring from buckling. Spring  62  is simply stretched between a bent tab  66  extending from sliding member  50  and a hole  68  in sliding member  52 .  
         [0031]    In some embodiments of the invention, filter assembly  12  includes one or more filter rails  70  that move to match the actual size of filter  24 , as opposed to its nominal size. Each rail  70  forms a channel adapted to receive filter frame  28 . If only one rail  70  is movable, the rail moves against filter frame  28  by moving toward a central portion of the rectangular shape of filter assembly  38 . If two rails  70  are movable, they are urged to move toward each other, as indicated by arrows  71 .  
         [0032]    One or more leaf springs  72  can be used to urge rails  70  against filter frame  28 . Leaf spring  72  includes a stressed bow  74  that abuts a flange  76  of side member  42 . A tab  78  extending from a central portion of bow  74  protrudes through a slot  80  in side member  42  and attaches to filter rail  70 . Tab  78  runs underneath an offset loop  82  formed of sheet metal in rail  42  and includes a barb  84  that helps hold tab  78  in place. Tab  78  moving within slot  80  defines the travel limit a tab  78  and filter rail  70 . Two tabs  86  bent from side member  42  helps hold bow  74  in position.  
         [0033]    A lead-in  88  at one end of rail  70  eases the installation of filter  24 , and a stop  90  at the opposite end of rail  70  defines the filter&#39;s fully installed position.  
         [0034]    Although the invention is described with reference to a preferred embodiment, it should be appreciated by those skilled in the art that other variations are well within the scope of the invention. Therefore, the scope of the invention is to be determined by reference to the claims, which follow.