Abstract:
A collapsible HVAC filter that includes a pleated filter media pack with ends that attach to ends of a planar filter frame member. The structure collapses by folding the filter frame member along score lines and compressing the pleated filter media while the media and frame member are attached. The collapsed components occupy little space relative to the expanded filter, and can be expanded to form a completed filter with little effort required by the end user. Most of the filter media is collapsed in a generally U-shaped channel formed from the folded filter frame member.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 61/598,950 filed Feb. 15, 2012. This prior application is hereby incorporated by reference. 
    
    
     STATEMENT REGARDING FEDERALLY-SPONSORED RESEARCH AND DEVELOPMENT 
     (Not Applicable) 
     REFERENCE TO AN APPENDIX 
     (Not Applicable) 
     BACKGROUND OF THE INVENTION 
     The invention relates generally to commercial and residential heating ventilation and air conditioning (HVAC) filtration, and more specifically to a collapsible filter that is collapsed to reduce shipping volume and is readily constructed by the end user. 
     Traditional pleated filters for commercial and residential HVAC systems include one or more frame members and a pleated filtration media glued to the frame members. As is known in the field, the filtration media is pleated to provide greater surface area on which to collect particulate. The greater surface area takes longer to clog the pores of the media with particulate, thereby prolonging the life of the filter media. Furthermore, pleated media tends to be stronger than planar media in resisting deformation due to the force of air passing through the media. However, pleated filters occupy a large volume of empty space per filter due to the shape of the pleated media. While such filters have low weight, they tend to be expensive to transport when considering them on a per unit volume basis due to the large amount of empty space per unit volume. 
     It is known to construct filters of materials that are collapsed by the manufacturer and assembled by end users. Such filters have significantly reduced shipping volumes, but require the end user to expand and construct the finished filter so that it can be used in a conventional manner. Conventional collapsible filters require the filter components to depart significantly from traditional non-collapsible filter components at a significant cost disadvantage. U.S. Pat. No. 3,938,973 discloses such a prior art collapsible filter, and includes a pinch frame furnace filter that requires a combination of framing materials including heavier paperboard, expensive plastic components and/or adhesive for the end user to assemble. There is also a higher tooling cost with the plastic components, because such components lead to less flexibility on filter sizes available. 
     The need exists for an improved collapsible filter that permits an end user to expand and construct the finished product rapidly, with minimal skill requirements and without the prior art&#39;s cost disadvantages. 
     BRIEF SUMMARY OF THE INVENTION 
     The invention contemplates a collapsible air filter with a pleated air filter media assembly, a method of collapsing the same, and the collapsed structure. The filter media has generally rectangular panels interconnected together in a pleated configuration with each panel connecting to at least one adjacent panel at longitudinal panel edges. A filter frame member is preferably made from a generally planar blank and has a central area with at least one opening formed therein. The central opening enables airflow through the filter so the air can pass through the media. The blank has laterally opposite side walls and longitudinally opposite end walls that are foldable to positions substantially perpendicular to the central area. 
     The filter frame member blank preferably has a plurality of substantially parallel score lines extending laterally across the filter frame member to define hinge points for the filter frame member to fold along. The filter frame member is preferably folded, along with the pleated air filter media assembly, to a substantially collapsed condition in which a substantially U-shaped channel is formed in the filter frame member and a majority of the panels of the pleated air filter media assembly are retained in the U-shaped channel. It should be understood that the U-shaped channel can be a different shape, but that a U-shaped channel has advantages. 
     At least two panels at opposite ends of the pleated air filter media assembly are attached to the end walls of the filter frame member so that, upon expansion of the collapsed filter frame member, the two filter media assembly panels remain attached to the end walls of the filter frame member during simultaneous elongation of the filter frame member and the pleated air filter media assembly. 
     In a preferred embodiment, a second filter frame member is configured to mount to the filter frame member. The second filter frame member is made from a generally planar blank having a central area with at least one opening formed therein, thereby enabling airflow therethrough. The second filter frame member has laterally opposite side walls and longitudinally opposite end walls foldable to positions substantially perpendicular to the central area, and is foldable to a substantially collapsed condition. 
     In an alternative embodiment, the air filter has frame panels extending from the end walls and the side walls of the filter frame member. The frame panels are configured to fold over lateral and longitudinal edges of the pleated air filter media assembly to positions substantially parallel to the central area when the air filter is expanded. These frame panels substitute for the second filter frame member to retain the pleated filter media assembly in the filter frame. 
     The entire filter collapses to a small portion of its original dimensions for smaller shipping volume. Any suitable paperboard frame material, which could be replaced or supplemented by thin stock plastic or other folding, rigid material, will work for the frame member or members. In the embodiment with two filter frame members, one frame member frictionally engages the other to enclose and finish the filter, and tabs extending from one frame member are inserted into slots formed in the other frame member. No plastic components are required to make a filter of suitable structural integrity. Adhesive can be used to attach the frame members to one another. The assembly is simplified and all parts are disposable. 
     In the preferred embodiment, the pleated media assembly is attached to a filter frame member and the frame member is folded along with, and around, the pleated media. The pleated media assembly can be adhered to the frame member or attached with tape, hooks and loops fasteners, glue or any other fastener. A separate second frame member is folded but does not have pleat media attached, and is packaged with the frame member and pleated media assembly combination. As an alternative, the second frame member can be pre-attached to the first frame member. In another alternative, one or more of the frame members do not cover the entire side walls of the pleated media assembly but only a portion of one or more sides. 
     The frame member of the preferred embodiment is preferably paperboard that is glued at the corners and scored along lines extending across its width so the frame member folds up with the pleated media assembly mounted in it. The frame members could be made of plastic or any other suitable material. When folded up, a preferably substantially U-shaped region of the frame contains most of the panels of the pleat pack, and the other regions of the frame are folded as shown and described in detail herein to maintain small size and very little air space. 
     The collapsible filter preferably does not use glue or plastic clips in the assembly, but still results in a structurally strong finished filter product. In addition, all of the components become part of the filter and are easily disposed of. The preferred design in the collapsed form occupies approximately 15% of the volume of the expanded (ready-to-use) filter. This greatly reduces the cost of shipping. As an example, a finished 16×25×4 inch filter collapses to fit into a space of 16×6×2.5 inches. Of course, other finished and collapsed sizes are contemplated and possible. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is a view in perspective illustrating a preferred embodiment of the present invention, including the collapsed frame member with pleated media assembly and collapsed frame member. 
         FIG. 2  is an end view illustrating the preferred embodiment of  FIG. 1 . 
         FIG. 3  is a view in perspective illustrating the collapsed frame member with pleated media assembly. 
         FIG. 4  is a schematic top view illustrating the frame member in a planar, pre-constructed state. 
         FIG. 5  is a schematic view in perspective illustrating the frame member in a constructed but pre-collapsed state. 
         FIG. 6  is a schematic end view illustrating the collapsed configuration of the frame member. 
         FIG. 7  is a view in perspective illustrating the collapsed frame member with pleated media assembly, and arrows indicating the direction of expansion. 
         FIG. 8  is a view in perspective illustrating the mostly expanded frame member with pleated media assembly. 
         FIG. 9  is a view in perspective illustrating the mostly expanded frame member. 
         FIG. 10  is a view in perspective illustrating the expanded frame member. 
         FIG. 11  is a view in perspective illustrating the expanded frame member with pleated media assembly. 
         FIG. 12  is a view in perspective illustrating the expanded frame member in position on the expanded frame member with pleated media assembly. 
         FIG. 13  is a view in perspective illustrating an alternative embodiment in which the frame member and pleated media assembly are expanded, and small flaps are upraised. 
         FIG. 14  is a view in perspective illustrating the embodiment of  FIG. 13  with the flaps mounted in their final position. 
         FIG. 15  is a view in perspective illustrating the preferred embodiment in a finished state. 
         FIG. 16  is an exploded view illustrating the preferred embodiment. 
         FIG. 17  is a view in perspective illustrating an alternative embodiment of the present invention. 
         FIG. 18  is an end view illustrating the embodiment of  FIG. 17 . 
         FIG. 19  is a view in perspective illustrating an alternative embodiment of the present invention. 
         FIG. 20  is a view in perspective illustrating the embodiment of  FIG. 19 . 
         FIG. 21  an end view illustrating a magnified view of the embodiment of  FIG. 19 . 
     
    
    
     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 
     Provisional patent application Ser. No. 61/598,950 is incorporated by reference into this application. 
     The preferred embodiment of the filter  10  is shown in a finished, assembled state in  FIG. 15 . The filter  10  of  FIG. 15  is illustrated in an exploded view in  FIG. 16 , showing the frame member  20 , the pleated media assembly  30  and the frame member  40 . The filter  10  is shown in a collapsed state or condition in  FIGS. 1, 2, 3 and 7 , and the components thereof will now be described with reference to the illustrations. 
     The frame member  20  is preferably formed from a single piece of planar paperboard, preferably in the shape shown in  FIG. 4 , but any suitable material will be acceptable. After forming, the frame member  20  is folded to form laterally opposite sidewalls  26  and  28  and longitudinally opposite end walls  22  and  24 , all of which are generally perpendicular to a central area  27  (see  FIG. 5 ). The frame member  20  is also folded in a novel way as described in detail below. Cutouts  25  are formed through the preferably paperboard of the central area  27  of the frame member  20  in a conventional manner, and thus provide openings through which air can flow when the completed filter  10  is in use. 
     In order to fold the frame member  20  to a desired, collapsed configuration, a series of folds are formed in the frame member, preferably by first scoring the frame member  20  along lines extending laterally across the frame member  20 , such as the substantially parallel score lines  21  and  23 , among others shown in  FIG. 4 . The score lines  21  and  23 , along with all other score lines formed in the frame member  20 , are conventional score lines. The scores can be cut scores, which are grooves formed by slicing into the material through a fraction of its thickness, such as about one-half. Alternatively, the scores can be perforations or they can be pressure scores that compress the material but do not cut into it. These score lines define hinge points that the frame member  20  folds along, and any particular filter can use one or more of these types of conventional scores depending upon the location and features desired. 
     The pleated media assembly  30  is a filtration media, preferably a synthetic non-woven filtration media having a thickness preferably less than one-eighth inch, a Frazier air permeability greater than about 100 cubic feet per minute (CFM) and a basis weight of from 30 to 120 grams per square meter. Of course, a person having ordinary skill in the field will understand that any suitable filtration media can be substituted for the preferred media with attendant benefits and disadvantages. The pleated media preferably has a conventional reinforcement layer to retain the pleated shape after pleating, and also to provide support to prevent the filtration media from “blowing out” of the filter frame during use. The reinforcement can be a conventional pleating reinforcement, such as slit and expanded metal or plastic, but it could also be netting, “chicken wire” or any conventional support layer. Alternatively, self-supporting pleatable material can be used. The pleated media assembly has end panels  32  and  34  (see  FIG. 16 ) that are preferably formed of the longitudinal end panels of the pleated media, but could alternatively be constructed of the longitudinal end panels mounted to paperboard or other rigid material panels. 
     The frame member  20  and the pleated media assembly  30  are mounted to one another, preferably prior to collapse of the combination as shown in  FIG. 1 . In the preferred embodiment, the end panels  32  and  34  of the pleated media assembly  30  are mounted, preferably by adhering, to the end walls  22  and  24 , respectively, of the frame member  20 . In this manner the pleated media assembly  30  is fixed to the frame member  20  at each of their longitudinal ends, thereby maintaining the ends of each attached to one another to move simultaneously during collapse and expansion. 
     The frame member  40  is preferably formed from a single piece of planar paperboard that is similar to the paperboard of the frame member  20 , preferably in a shape similar to that shown in  FIG. 4 . Other suitable materials can be substituted. The member  40  also has cutouts  45  formed through the paperboard of a central area through which air will flow when the filter  10  is in use. The frame member  40  is slightly longer and wider than the frame member  20  so that the frame member  40  can be slid onto the frame member  20  in the manner of a gift box as shown in  FIG. 12 . 
     After forming, the frame member  40  is folded and then glued to form side walls and end walls as shown in  FIG. 10 , and then is folded along substantially parallel lateral score lines  41 ,  43  and others to form the collapsed shape shown in  FIGS. 1 and 2 . In order to fold the frame member  40  to a desired configuration, a series of folds are formed in the frame member, preferably by first scoring the frame member  40  along lines, such as the score lines  41  and  43 , among others, as shown in  FIG. 9 . The score lines  41  and  43 , along with all other score lines formed in the frame member  40 , are conventional score lines as described above. 
     The frame member  40  is designed to mount to the frame member  20  with tabs in one member inserting into slots in the other member to retain the mounting condition. For example, as shown in  FIG. 1 , the tabs  160  and  162  are formed on the top edges of the frame member&#39;s end wall  22 . Corresponding slots  170  and  172  are formed at the base of the junction of the end wall  42  and the central area of the frame member  40 . When the frame member  40  is placed over the frame member  20 , the tabs  160  and  162  are inserted in the slots  170  and  172  to fix the frame members  20  and  40  together, particularly against any force in the pleated media assembly  30  that tends to return the pleated media assembly  30  toward its collapsed condition. 
     Similar tabs are formed at the corners of the frame member  20  (see tabs  164  and  166  in  FIG. 16 ) and slots are formed at the corners of the frame member  40  (see slots  174  and  176  in  FIG. 16 ). When the frame member  40  is placed over the frame member  20 , the tabs  164  and  166  (along with other, similar tabs at the remaining corners) insert into the slots  174  and  176 , respectively (along with other, similar slots at the remaining corners), to fasten the frame member  40  to the frame member  20 . 
     In order to reduce the volume of the filter  10  prior to shipping, the combination of the frame member  20  and the pleated media assembly  30  is collapsed into a very compact structure in the configuration shown in  FIGS. 1, 2, 3, 6 and 7  and 
     In order to accomplish this collapsed condition, the frame member  20  is folded along the score lines  21  and  23 , among others, with the end panels  32  and  34  of the pleated media assembly  30  attached to the end walls  22  and  24 . Thus, the end walls  22  and  24  remain substantially parallel to one another and to the end panels  32  and  34 , and the pleats of the assembly  30  are compacted between the two end walls  22  and  24 , as shown in  FIGS. 1, 2, 3 and 7 . 
     During collapsing of the pleated media assembly  30  and the frame member  20 , the location of each panel of the pleated media assembly  30  is designed to fit within the collapsed frame member  20 , as will now be described with reference to the illustrations of  FIGS. 3 through 6 . As shown in the illustrations, the frame member  20  has end walls  22  and  24  to which the end panels  32  and  34 , respectively, are mounted. One panel of the pleated media assembly  30  is inserted in the leftward most cavity of the frame member  20 , and the end panel  32  is attached to the underside (in the orientation shown in  FIG. 6 ) of the end wall  22 . The remaining panels of the pleated media assembly  30  extend to the right in the orientation shown in  FIG. 6 . The first panel  33  (see  FIG. 3 , which is inverted relative to  FIGS. 5 and 6 ) to the right of the end panel  32  extends over the frame member segments D, E, F and G, allowing the remaining panels of the pleated media assembly  30  to be held in a U-shaped channel formed by the end member segments B, C and D. The panel  34  extends from the large cluster of panels in the U-shaped channel to attachment to the end wall  24  of the frame member  20 . Most of the panels of the pleated media assembly are compressed and inserted in the U-shaped channel that forms a larger cavity in the frame member  20 . Preferably, there are no pleats of the pleated media assembly in the V-shaped channel rightward of the U-shaped channel, but the next rightward channel contains another panel of the pleated media assembly. 
     While the pleated media assembly  30  and the frame member  20  are collapsed in this configuration, the side walls  26  and  28  of the frame member  20  extend well beyond the lateral ends of the pleated media assembly panels. After expansion, the side walls  26  and  28  are bent upwardly to substantially perpendicular relative to the end walls  22  and  24 , as shown in the progress from  FIG. 8  to  FIG. 11 . It is preferred that during manufacture (and thus prior to expansion) of the combined frame member  20  and the pleated media assembly  30 , the frame end walls  22  and  24  are mounted to the frame side walls  26  and  28  using adhesive, fasteners or other suitable means. The overlapping portions of the end walls and sidewalls are folded parallel to the respective end walls  22  and  24  when the structure is in its collapsed state, and when the structure is expanded those overlapping portions fold out and are coplanar to the sidewalls  26  and  28  (and thus perpendicular to the end walls  22  and  24 ). 
     It should be understood that the number of channels in the frame member  20  with and without pleated panels will be determined by the size of the filter and could differ from that shown. For example, smaller filters of the same height would have less folding and no channels without panels. Although a U-shaped channel is described above as containing most of the pleated panels of the pleated media assembly  30 , it will become apparent to a person of ordinary skill that the shape of the channel containing the majority of the pleated panels is not critical. While the U-shaped channel has advantages, another shape could have most or many of those advantages while providing other advantages. Thus, a wide and deep V-shaped channel could be substituted for the U-shaped channel, as could a W-shaped channel or multiple adjacent or spaced V-shaped channels. 
     The collapsed configuration shown in  FIGS. 1-3  allows the collapsed pleated media assembly  30  to be mounted in the collapsed frame member  20  during construction, and remain in this condition during shipping and subsequent storage of the components as long as the components are maintained in this condition, such as by bands, shrink wrap, boxes or any other suitable restraint. During expansion and assembly of the collapsed filter components, the frame member  20  and pleated media assembly  30  are expanded by longitudinal elongation. This can be accomplished by releasing the restraint on the collapsed combination and grasping the end walls  22  and  24  and manually forcing them apart from one another. This is carried out until the frame member  20  and pleated media assembly  30  reach a final length, which will be apparent due to the central area  27  attaining a substantially flat condition. The sidewalls  26  and  28  are then manually placed in the substantially perpendicular orientation relative to the central area  27 . The second frame member  40  is then placed over the frame member  20  in the manner of a gift box as shown in  FIG. 12  and the two frame members  20  and  40  are pushed together to create the filter assembly shown in  FIG. 15 . 
     When in the collapsed condition, the components of the filter  10  are packaged as tightly and small as feasible so that, during shipping and subsequent storage, they maintain their compact size and thus keep shipping and storage costs low. Once the filter  10  is removed from the packaging and expanded, the filter  10  consumes the same space of a conventional filter of its size, and operates to filter air in an HVAC system in a conventional manner—by filtering the air forced through the filter media thereof. 
     A preferred feature of the invention is flexible ribbons  290  (see  FIGS. 3 and 11 ) of fabric, polymer strips, yarn or any other suitable flexible material that are attached, such as by adhesive, ultrasonic or thermal bonding or any other means, to the tips of the pleats where the edges of each pair of adjacent rectangular panels are joined. The ribbons  290  are used to maintain substantially consistent spacing between the tips of the pleats upon expansion, and to prevent excessive expansion of the pleated filter media assembly  30 . A person having ordinary skill will understand from this description that other filter media materials can be used that do not require such ribbons  290 , and that the ribbons  290  can be used on only one side of the pleated media assembly  30 . Alternatively, it will become apparent that other means of spacing can be used, such as extending string through openings in the pleated filtration media, providing a traditional finger-like pleat separator made out of paperboard or plastic, or any other suitable spacing methods or any other suitable attachment means. 
     An alternative embodiment of the present invention is shown in  FIGS. 13 and 14 . The frame member  120  is substantially identical to the frame member  20 , with the exception of the panels  122 ′,  124 ′,  126 ′ and  128 ′ extending from the ends  122  and  124  and the sides  126  and  128 , respectively. Upon expansion of the frame member  120  from the collapsed to the elongated state, the panels  122 ′,  124 ′,  126 ′ and  128 ′ are bent over to a substantially perpendicular orientation relative to the side walls or end walls from which they extend. Each of the panels  122 ′,  124 ′,  126 ′ and  128 ′ is fastened at its ends to next adjacent panels, such as by adhesive or some other suitable fastener. This alternative embodiment has the advantage that no second frame member is required to retain the pleated media assembly within the frame, because the panels  122 ′,  124 ′,  126 ′ and  128 ′ retain the pleated media assembly once they are fastened in their final position. 
     As shown in  FIGS. 17 and 18 , a guide  200  can be integrated into, or attached to, the sidewall  246  of a second frame member  240 . The second frame member  240  is preferably similar to the second frame member  40 , described above, inasmuch as it has a planar central area with openings for air flow, along with sidewalls and end walls substantially perpendicular to the central area and that frictionally engage the sidewalls and end walls of a frame member substantially similar to the member  20  described and shown herein. The second frame member&#39;s  240  sidewalls form the outer lateral surface of the finished filter, and, therefore, the guide  200  extends from one sidewall  246  to engage a rail  210  in a conventional HVAC system. The guide  200  thus maintains the attached filter within the conventional HVAC system and reduces air bypassing the filter. 
     An alternative, or complement, to the guide  200  is shown in  FIGS. 18 and 19 . A flexible seal extension  300  is mounted at the top of the filter  310  on the upstream side and a similar flexible seal extension  302  is mounted at the bottom of the filter  310  on the upstream side. The seal extensions  300  and  302  are preferably either formed integral to the frame of the filter  310 , or are mounted thereto, such as by double-sided tape, adhesive or any suitable fastener. The seal extensions  300  and  302  are preferably substantially L-shaped and the cantilevered leg of each can pivot away from the filter  310  to contact an adjacent surface of the HVAC structure that holds the filter  310 , such as the floor  304  of the frame  306  (see  FIG. 20 ) or the rail  308 . This contact forms an air seal and an angled air guide that greatly reduces the amount of air that would, without the seal extensions, otherwise bypass the filter  310 . 
     The seal extensions  300  and  302  are able to pivot relative to the filter  310  because the material of which they are constructed is deflected under the force of the air blowing through the structure holding the filter  310 . If the material of which the seal extensions  300  and  302  is more rigid than would alone permit sufficient deflection, a “hinge” can be formed at the juncture of the legs that permits the cantilevered leg of each seal extension to pivot relative to the leg attached to the filter  310 . Such a hinge is preferably formed by scoring the material of which the seal extension is constructed, but can also be formed by any known hinge. 
     In an alternative, the seal extensions  300  and  302  can be rigid and have no hinge to permit pivoting if they are constructed with precise size and orientation to seat against an adjacent surface to form a seal without such pivoting. Still further, seal extensions can be mounted to the downstream side of the filter  310 . 
     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.