Adjustable air filter

Abstract

An adjustable air filter for use in heating, ventilating, cooling, and forced air systems. The air filter includes a media for filtering air and adapted to be cut with scissors, and a frame embracing the peripheral edges of the media. The frame includes a pair of male sections and a pair of female sections respectively telescopingly receiving the male sections. Also, the frame is adapted to be cut with scissors and is preferably formed of polyvinyl chloride. Each of the male sections includes a T-shaped projection and each of the female sections includes a complementary shaped T-shaped slot adapted to telescopingly receive the T-shaped projection for preventing inward separation of the sections from one another. In the preferred form the media is of the electrostatic type and includes at least one layer of polypropylene woven in an egg-crate pattern. Also, the layer preferably includes a pad of washable polyester material. At least one grid, having squares defining interstices, is formed of polypropylene and is heat staked into the layer of polypropylene for permanent attachment thereto. Self-tapping screws are provided to lock the sections of the frame together against telescoping separation thereof.

I claim: 
     
       1. An air filter for use in heating, ventilating, cooling, and forced air systems, said air filter including an adjustable frame having four sides, said frame comprising: (a) at least one female section having at least one channel-shaped leg;   (b) at least one male section having at least one channel-shaped leg telescopingly mated with said female section to establish one of said sides of said frame;   (c) coacting means on said leg of said female section and on said leg of said male section for permitting lengthwise telescoping movement of said leg of said male section and said leg of said female section relative to one another and yet preventing inward separation of said leg of said female section from said leg of said male section, said coacting means including a T-shaped projection attached to said male section and extending longitudinally of said male section and a slot in said female section extending longitudinally of said female section, said slot being complementary shaped and sized relative to said projection for closely telescopically receiving said projection; and   (d) locking means for locking said leg of said female section and said leg of said male section in a fixed assembled position relative to one another.   
     
     
       2. The air filter of claim 1 in which said male section and said female section are formed of polyvinyl chloride. 
     
     
       3. An adjustable air filter for use in heating, ventilating, cooling, and forced air systems, said air filter comprising: (a) media means for filtering air, said media means having a peripheral edge; and   (b) frame means embracing said peripheral edge of said media means; said frame means including: (i) a pair of female sections each having a channel-shaped first leg and a channel-shaped second leg perpendicular to said first leg;   (ii) a pair of male sections each having a channel-shaped first leg and a channel-shaped second leg perpendicular to said first leg, said first legs of said male sections being respectively telescopingly mated with said second legs of said female sections and said second legs of said male sections being respectively telescopingly mated with said first legs of said female sections to establish four sides to said frame means; and   (iii) coacting means on said first and second legs of said female sections and on said first and second legs of said male sections for permitting telescoping movement of said first legs of said male sections and said second legs of said female sections relative to one another and yet preventing inward separation of said first legs of said female sections from said second legs of said male sections and preventing inward separation of said second legs of said female sections from said first legs of said male sections, said coacting means including T-shaped projections respectively attached to said male sections and extending longitudinally of said male sections to which .Iadd.said projections are .Iaddend.attached and slots respectively in said female sections extending longitudinally of said female sections, said slots being complementary shaped and sized relative to said projections for closely telescopically receiving said projections.     
     
     
       4. The air filter of claim 3 in which said male sections and said female sections are formed of polyvinyl chloride. 
     
     
       5. The air filter of claim 3 in which said media means includes at least one electrostatic layer and at least one grid including a multiplicity of squares having intersecting legs establishing interstices for the passage of air therethrough. 
     
     
       6. The air filter of claim 5 which includes button means for permanently attaching said grid to said layer. 
     
     
       7. An adjustable air filter for use in heating, ventilating, cooling, and forced air systems, said air filter comprising: (a) media means for filtering air, said media means having a peripheral edge and said media means being formed of a material as may be cut with scissors; and   (b) a frame formed of a material as may be cut with scissors, said frame embracing said peripheral edge of said media means and including: (i) a first female section having a first leg and a second leg substantially perpendicular to said first leg of said first female section, said first female section being channel-shaped in cross section and each leg thereof including a web and a pair of spaced flanges;   (ii) a second female section having a first leg and a second leg substantially perpendicular to said first leg of said second female section, said second female .[.second.]. .Iadd.section .Iaddend.being channel-shaped in cross section, and each leg thereof including a web and a pair of spaced flanges;   (iii) a first male section having a first leg and a second leg substantially perpendicular to said first leg of said first male section, said first male section being channel-shaped in cross section, and each leg thereof including a web and a pair of spaced flanges, said first leg of said first male section being telescopically mated with said second leg of said first female section for movement of said first leg of said first male section and said second leg of said first female section lengthwise relative to one another with said web of said first leg of said first male section being adjacent said web of said second leg of said first female section, and said second leg of said first male section being telescopically mated with said first leg of said second female section for movement of said second leg of said first male section and said first leg of said second female section lengthwise relative to one another with said web of said second leg of said first male section being adjacent said web of said first leg of said second female section;   (iv) a second male section having a first leg and a second leg substantially perpendicular to said first leg of said second male section, said second male section being channel-shaped in cross section, and each leg thereof including a web and a pair of spaced flanges, said first leg of said second male section being telescopically mated with said second leg of said second female section for movement of said first leg of said second male section and said second leg of said second female section lengthwise relative to one another with said web of said first leg of said second male section being adjacent said web of said second leg of said second female section, and said second leg of said second male section being telescopically mated with said first leg of said first female section for movement of said second leg of said second male section and said first leg of said first female section lengthwise relative to one another with said web of said second leg of said second male section being adjacent said web of said first leg of said first female section;   (v) coacting means on said first and second female sections and on said first and second male sections for permitting telescoping movement of said first and second female sections and yet for preventing inward separation of said first leg of said first female section from said second leg of said second male section, for preventing inward separation of said second leg of said first female section from said first leg of said first male section, for preventing inward separation of said first leg of said second female section from said second leg of said first male section, and for preventing inward separation of said second leg of said second female section from said first leg of said second male section, said coacting means including T-shaped projections respectively attached to said male sections and extending longitudinally of the male sections to which .Iadd.said projections are .Iaddend.attached; ribs respectively attached to said female sections and extending inwardly from said webs of said female sections; and T-shaped slots respectively in said female sections extending through said webs of said female sections and into said ribs; said slots being complementary shaped and sized relative to said projections for closely telescopically receiving said projections; and   (vi) locking means for locking said first and second female sections and said first and second male sections in fixed assembled position relative to one another.     
     
     
       8. The air filter of claim 7 in which said locking means includes at least one aperture through said web of one of said female sections and at least one self-tapping screw extending through said aperture, through said T-shaped slot of said one of said female sections and into said rib of said one of said female sections. 
     
     
       9. The air filter of claim 8 in which said male sections and said female sections are formed of polyvinyl chloride such as may be cut to any desired length; in which said media includes at least one electrostatic layer formed of polypropylene such as may be cut to any desired size and a pad formed of washable polyester such as may be cut to any desired size; in which is included at least one grid formed of polypropylene such as may be cut to any desired size; and in which polypropylene attachment means is provided for permanently attaching said grid to said electrostatic layer. 
     
     
       10. An adjustable frame for use in heating, ventilating, cooling, and forced air systems, said frame having four sides and comprising: (a) at least one female section having at least one channel-shaped leg;   (b) at least one male section having at least one channel-shaped leg telescopingly mated with said female section to establish one of said sides of said frame;   (c) coacting means on said leg of said female section and on said leg of said male section for permitting lengthwise telescoping movement of said leg of said male section and said leg of said female section relative to one another and yet preventing inward separation of said leg of said female section from said leg of said male section, said coacting means including a T-shaped projection attached to said male section and extending longitudinally of said male section and a slot in said female section extending longitudinally of said female section, said slot being complementary shaped and sized relative to said projection for closely telescopically receiving said projection; and   (d) locking means for locking said leg of said female section and said leg of said male section in a fixed assembled position relative to one another. .Iadd.   
     
     
       11.  An air filter for use in forced air systems, comprising: a filter media for filtering air, the filter including at least a first thermoplastic electrostatic layer and at least a first thermoplastic stiffening grid having interstices for the passage of air therethrough; and   at least one heat and pressure formed connection that permanently attaches the grid to the electrostatic layer at the location of the connection. .Iaddend. .Iadd.   
     
     
       12.  The filter of claim 11, wherein the filter comprises a plurality of said connections formed by applied heat and pressure to the filter media at the locations of the connections. .Iaddend. .Iadd. 
     
     
       13.  The filter of claim 12, wherein the stiffening grid includes intersecting legs establishing the interstices. .Iaddend. .Iadd.14. The filter of claim 13, wherein the filter media has a peripheral edge, and further comprising a frame embracing the peripheral edge of the filter media. .Iaddend. .Iadd.15. The filter of claim 13, wherein the connections are located at intersections of the legs, such that the electrostatic layer is permanently attached to the grid at the intersections. .Iaddend. .Iadd.16. The filter of claim 15, wherein the connections comprise buttons 
     
     
        located at the intersections. .Iaddend. .Iadd.17.  The filter of claim 16, wherein the distal ends of pins comprise said locations of said applied 
     
     
        heat and pressure at the intersections. .Iaddend. .Iadd.18.  The filter of claim 11, wherein the filter media further comprises a second electrostatic layer permanently attached to a second grid, the first electrostatic layer and first grid being positioned parallel to the second electrostatic layer and second grid, and a center pad interposed therebetween. .Iaddend. .Iadd.19. The filter of claim 18, further comprising a frame positioned to hold the first and second electrostatic layers in contact with opposite sides of the center pad, and the first and second grids are disposed on opposite outer sides of the filter media. 
     
     
        .Iaddend. .Iadd.20.  The filter of claim 13, wherein the interstices 
     
     
        comprises a multiplicity of squares. .Iaddend. .Iadd.21.  An air filter for use in forced air systems, comprising: a filter media for filtering air, the filter including at least a first thermoplastic electrostatic filter and at least a first thermoplastic stiffening grid having interstices for the passage of air therethrough; and   a plurality of heat and pressure formed buttons that attach the grid to the   
     
     
        electrostatic filter at the locations of the buttons. .Iaddend. .Iadd.22. The filter of claim 21, further comprising a plurality of pins extending from the grid through the electrostatic filter, wherein said pins comprise said locations of said applied heat and pressure to said buttons. 
     
     
        .Iaddend. .Iadd.23.  The filter of claim 21, wherein the stiffening grid includes intersecting legs establishing the interstices. .Iaddend.