Abstract:
An apparatus and method for an air filter media and frame having structural support members, including a tensile support member.

Description:
CROSS-REFERENCE TO RELATED DOCUMENTS 
     None. 
     TECHNICAL FIELD 
     The invention relates generally to an apparatus for filtering particulates from a stream of air. More specifically, the invention relates to an air filter having an improved support structure to increase resistance to deformation. 
     BACKGROUND 
     It is desirable to provide filter media in certain streams of air to remove particulates from streams of air because such particulates can cause damage to equipment, for example, HVAC equipment. It is further desirable to provide filtering media that is efficient, has a long operating life, and has consistent operating characteristics. 
     It is common in the art to use a filtering media that may be made of any of a variety of materials, including, for example, media made primarily of non-woven cotton-polyester fiber blends. However, non-woven cotton-polyester fiber blends have inherent variability in performance, primarily due to the inconsistency of the fiber diameter in these blends. Additionally, more inconsistency is introduced by additives such as tackifiers or binder agents, which are often used with cotton-polyester fiber blends to increase filter efficiency, because these additives tend to build up in some areas. 
     One means to combat this inconsistency is to use as a filtering media non-woven blends based on polyester or polyethylene virgin fibers. The increased consistency when using blends based on polyester or polyethylene virgin fibers results primarily from the ability to manufacture these fibers with relatively low variation in diameter from fiber to fiber, as well as from the fact that these blends are effective without additional tackifiers or binder agents. However, filtering media composed primarily of polyester or polyethylene virgin fibers tends to be stiffer than filtering media using cotton-polyester fiber blends. This stiffness can create a problem in filters utilizing a cardboard frame. 
     It is common in the art to use cardboard frames to provide structural support for the filtering media. Such frames often form a perimeter around the filtering media and include a plurality of support trusses. Angled trusses transfer tension from the top and bottom sides of the frame perimeter to the left and right sides of the frame perimeter. These angled trusses also help resist torsion of the frame. During assembly, frames may be stretched to accept the filtering media. If the media is too stiff it may overcome the yield point of the frame and cause deformation of the frame. Such deformation may prevent the frame from returning to its original shape. This inability of the frame to return to its original shape is especially prevalent when materials such as cardboard or beverage board are used to construct the frame. The deformation causes tension in the truss members, which in turn pulls the left and right sides of the frame inwardly. The deformation of the frame may cause bowing. This bowing is problematic, especially where filters are placed side by side in operation, because bowing of the frame creates gaps through which air can flow unfiltered. 
     One solution to the problem of frame deformation is to use a more rigid frame. Plastics or metals, for example, may be used to construct the frame and thereby increase its rigidity. However, these materials are prohibitively expensive in comparison to cardboard and other materials. 
     Thus, it would be highly desirable to use a stiffened filtering media made of, for example, polyester or polyethylene virgin fibers, contained within a cardboard, or similar, frame that has increased resistance to deformation. 
     SUMMARY 
     The present disclosure is directed towards inventive methods and apparatus for an air filter with one or more tensile support members. The air filter with tensile support member is, in various embodiments, a frame around an outer perimeter of a filter media that also includes a plurality of structural support members extending across the front and/or back faces of the filter media. The air filter with tensile support member may also include a media backing structure for, among other things, maintaining a shape or orientation of the filter media. The plurality of structural support members may include one or more tensile support members that enhance the rigidity of the frame, thus aiding in the ability of the frame to resist deformation. 
     Generally, in one aspect, an air filter with tensile support member is provided for filtering a stream of air and having improved structural rigidity. The air filter with improved tensile support includes a pleated filter media having a stiffness of at least about 600 Gurley and having a machine direction and a transverse direction that is transverse to the machine direction, thus defining a first plane that is transverse to the flow of the stream of air. The pleated filter media has pleat valleys, extending from the top to the bottom of the filter media that are continuous and substantially uninterrupted from top to bottom. The air filter further includes a frame having one or more frame members that have an inner perimeter for accepting an outer perimeter of the filter media, a frame front surface, a frame rear surface, and a plurality of structural support members. The filter media has a width in the transverse direction that is wider than a width of the inner perimeter of the frame in the transverse direction. The frame front and/or rear surfaces include a plurality of angled support members as well as one or more tensile support members to enhance the structural rigidity of the frame. The tensile support member or members extend in the transverse direction. The filter media is interposed between the frame front and rear surfaces. 
     In some embodiments, the plurality of structural support members includes a second tensile support member extending in the machine direction. 
     In some embodiments, there is a media backing structure interposed between the filter media and the frame. 
     In some embodiments, the frame front surface overlaps the frame rear surface. 
     In some embodiments, the filter media is made of polyester fibers. 
     In some embodiments, the filter media is made of polyethylene fibers. 
     In some embodiments, the frame is constructed of cardboard. 
     Generally, in another aspect, an air filter with tensile support member is provided which includes a frame having a front frame surface with an opening and a rear frame surface also having an opening. In this aspect, also included is a pleated filter media having a stiffness of at least about 600 Gurley retained within the frame. The filter media extends in a transverse direction from its top to its bottom and has a plurality of pleat valleys also extending from top to bottom continuously and substantially uninterrupted. The filter media has a length from top to bottom that is greater than a length of the frame from top to bottom. One of the front frame surface and rear frame surface has at least one tensile support member and a plurality of angled support members. The at least one tensile support member extends substantially parallel to the transverse direction across an air flow opening, and the plurality of angled supports are angled substantially equally relative to the at least one tensile support member. 
     In some embodiments, there is also included a media backing structure interposed between the filter media and the frame. 
     In some embodiments, the frame front surface overlaps the frame rear surface. 
     In some embodiments, the frame rear surface overlaps the frame front surface. 
     In some embodiments, the pleated filter media is formed of polyester fibers. 
     In some embodiments, the pleated filter media is formed of polyethylene fibers. 
     In some embodiments, the frame is constructed of cardboard. 
     In another aspect, a method is detailed for forming an air filter with improved tensile support. The method includes providing a frame rear having an outer perimeter and a plurality of angled support members and one or more tensile support members, as well as providing a frame front having an outer perimeter. The method also includes applying an adhesive to the frame rear and inserting a filter media having a stiffness of at least about 600 Gurley into the frame rear so that the filter media contacts the adhesive, then stretching the frame front and/or the frame rear, and attaching one or more attachment members of the frame front to one or more attachment members of the frame rear. 
     In some embodiments, the frame front also has a plurality of angled support members angled relative to the tensile support member or members. 
     In some embodiments, the method also includes providing a media backing structure interposed between the filter media and the frame. 
    
    
     
       BRIEF DESCRIPTION OF THE ILLUSTRATIONS 
       The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  depicts a perspective view of an embodiment of an air filter with tensile support member; 
         FIG. 2  depicts an exploded assembly view of another embodiment of an air filter with tensile support members; 
         FIG. 3A  depicts a front view of multiple air filters arranged side by side, each without tensile support members. 
         FIG. 3B  depicts a front view of an embodiment of multiple air filters arranged side by side, each having tensile support members. 
     
    
    
     DETAILED DESCRIPTION 
     It is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless limited otherwise, the term “attached” and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings. In addition, the term “attached” and variations thereof are not restricted to physical or mechanical connections or couplings. 
     Referring initially to  FIG. 1 , an embodiment of an assembled air filter  100  with a tensile support member  155  is shown having a frame  105  framing a filter media  130 . The frame  105  includes a frame front  110 , a frame top member  112 , a frame bottom member  114 , a frame first side member  116 , a frame second side member  118 , a plurality of front angled support members  152 , and the front tensile support member  155 . The frame top member  112 , the frame second side member  118 , the frame bottom member  114 , and the frame first side member  116  form an inner perimeter. This inner perimeter has an inner-frame width W1 in a first, or transverse, direction T. The term “width” as used herein is used as a measurement of distance from top to bottom, or from side to side, whichever is being referenced. Referring now to  FIG. 2 , an embodiment of an unassembled air filter  200  with tensile support members  155 ,  156 ,  255 ,  256  is depicted having a front top attachment member  142  that may be folded about a front top score  143  toward a frame rear  240  until the front top attachment member  142  is substantially perpendicular to the frame front  110 . A rear top attachment member  242  may be folded about a rear top score  243  toward the frame front  110  until the rear top attachment member  242  is substantially perpendicular to the frame rear  240 . Thus, the front top attachment member  142  and the rear top attachment member  242  may be attached and/or assembled to form the frame top member  112  depicted in  FIG. 1 . Similarly, a front bottom attachment member  144 , a front first side attachment member  146 , and a front second side attachment member  148  may be folded about respective front scores  145 ,  147 ,  149 . A rear bottom attachment member  244 , a rear first side attachment member  246 , and a rear second side attachment member  248  may be folded about respective rear scores  245 ,  247 ,  249  so that the bottom attachment members  144 ,  244  may be attached to each other, the first side attachment members  146 ,  246  may be attached to each other, and the second side attachment members  148 ,  248  may be attached to each other, thereby forming the frame bottom  144  and other frame sides  116 ,  118  depicted in  FIG. 1 . In this embodiment, the frame front  110  is substantially planar and includes the plurality of front angled support members  152  and the front tensile support members  155 ,  156 . Each of the frame top member  112 , the frame bottom member  114 , the frame first side member  116 , and the frame second side member  118  are substantially planar and oriented in  FIG. 1  such that each of the side members  112 ,  114 ,  116 ,  118  are substantially perpendicular to the frame front  110 . Similarly, the frame  105  includes a frame rear  240  (see  FIG. 2 ) that is substantially planar and substantially parallel to the frame front  110  and, although not shown in  FIG. 1 , substantially perpendicular to the side members  112 ,  114 ,  116 ,  118 . The frame rear  240  includes a plurality of rear angled support members  252  and rear tensile support members  255 ,  256 . The angled support members  152 ,  252  are depicted in this embodiment as extending at approximately a 45 degree angle relative to the transverse direction T and/or a second, or machine, direction M. It is understood however, that angled support members  152 ,  252  may extend at any angle relative to said the transverse direction T and/or machine direction M and need not be symmetric. 
     Referring now to  FIGS. 1 and 2 , the filter media  130  is illustrated as substantially pleated, having a plurality of pleat tips  132  that are substantially coplanar and a plurality of pleats  134  that are “fan folded” or “accordion folded.” The plurality of pleats  134  are arranged side by side in the machine direction M and each pleat  134  extends in the transverse direction T, which, in this embodiment, is substantially perpendicular to the machine direction M. The plurality of pleats  134  extend in the machine direction M from the frame first side member  116  to the frame second side member  118 , and each pleat  134  extends in the transverse direction T from a filter media top  231  to a filter media bottom  233 . The plurality of pleats  134  form a plurality of pleat valleys that continue substantially uninterrupted from a filter media top  231  to a filter media bottom  233 . This uninterrupted disposition of pleat valleys allows for even pressure distribution across the face of the filter media  130  and/or reduces pressure drop through the filter media  130 . Also, the plurality of pleat tips  132  lie in a plane that is substantially coplanar with the frame front  110 . Additionally, the filter media  130  is depicted having a filter media first side  235  and a filter media second side  237 . The filter media top, bottom, and sides  231 ,  233 ,  235 ,  237  define a perimeter around filter media  130 . A media backing structure  220  is included to help the filter media  130  maintain its shape and/or orientation. In this embodiment, the media backing structure  220  may be shaped to flushly mate with the filter media  130  and may be interposed between the filter media and the frame front  110 , the frame rear  240 , or both. It is further understood that, while  FIGS. 1-3  illustrate the air filter  100 ,  200 ,  400  with tensile support member  155 ,  156 ,  157 ,  158 ,  255 ,  256  as substantially square in shape, it may be any shape, including, but not limited to, rectangular, triangular, polygonal, round, cylindrical, or any other shape. The filter media  130  has a width W2 measured in the transverse direction T from the filter media bottom  233  to the filter media top  231 . Unassembled, as shown in  FIG. 2 , the filter media width W2 is larger than the inner-frame width W1, as shown in  FIG. 1 . The width W2 is slightly larger than the distance of the inner perimeter of frame front  110  and/or frame rear  240  as measured in the transverse direction T from bottom score  145 ,  245  to top score  143 ,  243 . The distance of the inner perimeter of frame front  110  and/or frame rear  240  as measured in the transverse direction T may also be referred to as the inner-frame width W1. Thus, frame  105  is stretched in the transverse direction T to be assembled around filter media  130 . The frame  105  may be stretched by hand as, for example, when a human operator assembles the frame  105  around the filter media  130 . For example, the human operator may form three frame side members  114 ,  116 ,  118  by attaching the corresponding attachment members  144 ,  244 ,  146 ,  246 ,  148 ,  248 , respectively, leaving the frame top member  112  temporarily unassembled. The human operator may then insert the filter media  130  into the frame  105  between the top attachment members  142 ,  242 . When the filter media  130  is inside the frame  105 , the operator may stretch by pulling in the transverse direction T the frame front  110  and the frame rear  240  until wide enough in the transverse direction T to fold and attach top attachment member  142 ,  242  over the filter media top  231 , thus creating a friction fit of the filter media  130  inside the frame  105 . It is understood that machines and/or other automated processes may be used in lieu of, or in conjunction with, manual operations to perform the stretching and/or other assembly functions. Generally, in some embodiments, the frame  105  may need to be stretched up to 0.25″ in the transverse direction T away from its normal position. This stretching may be permanent if the frame  105  is not allowed to relax back, as may be the case, for example, if the filter media  130  is stiff enough to resist the frame  105  relaxing back to its normal position. However, it is understood that the presence and/or degree of stretching of frame  105  may be made permanent once the attachment members  142 ,  242 ,  144 ,  244 ,  146 ,  246 ,  148 ,  248  are attached together as described above. 
     Referring now to  FIG. 2 , the frame front  110  is depicted as substantially planar and includes the plurality of front angled support members  152  and two front tensile support members  155 ,  156 . In this embodiment, the front tensile support member  155  is perpendicular to the other front tensile support member  156 . Although possible that only one front tensile support member  155 ,  156  will be in tension in use and the other tensile support member  155 ,  156  will be in compression in this embodiment, inclusion of at least one tensile support member  155 ,  156  in each direction T, M helps, for example, to ensure that at least one tensile support member  155 ,  156  is oriented parallel to the transverse direction T notwithstanding operator error or other error during assembly. The frame front  110  has attached thereto a front top attachment member  142 , the front bottom attachment member  144 , the front first side attachment member  146 , and the front second side attachment member  148 . Each of the front attachment members  142 ,  144 ,  146 ,  148  is substantially planar and substantially coplanar with frame front  110 . The frame rear  240  is substantially planar and substantially parallel to the frame front  110 . The frame rear  240  includes the plurality of rear angled support members  252  and two rear tensile support members  255 ,  256 . As with tensile support members  155 ,  156  in this embodiment, one tensile support member  255 ,  256  may be in tension while the other tensile support member  255 ,  256  may be in compression, for substantially the same reason as described above. The frame rear  240  has attached thereto the rear top attachment member  242 , the rear bottom attachment member  244 , the rear first side attachment member  246 , and the rear second side attachment member  248 . Each of the rear attachment members  242 ,  244 ,  246 ,  248  is substantially planar and substantially coplanar with frame rear  240 . In this embodiment, the air filter  200  with tensile support members  155 ,  156 ,  255 ,  256  may be assembled including the frame front  110 , the filter media  130 , and the frame rear  240 , as well as a media backing structure  220 . The media backing structure  220  may be included to provide additional support to the filter media  130 . The media backing structure  220  is depicted as a structure having a relatively high open area and may be constructed of, for example, expanded metal, a welded wire grid, chicken wire, fingers, cardboard inserts, any other metallic or non-metallic support, or other stiffening media structures as are known in the art which increase the rigidity of the pleated media. It is understood that the media backing structure  220  may be made of any of a variety of materials, or a combination thereof. It is further understood that the media backing structure  220  may be oriented in any of a variety of ways, including, but not limited to, a mesh or similar framework, and the media backing structure  220  may be oriented parallel or transverse to the transverse direction T and/or the machine direction M. In the embodiment shown in  FIGS. 1-3B , the frame front  110 , the filter media  130 , and the frame rear  240  may be oriented in close proximity so that the pleat tips  132  of the filter media  130  are substantially coplanar with the frame front  110 , and so that pleat tips  232  are substantially coplanar with the frame rear  240 . 
     Referring again to  FIGS. 1 and 2 , the distance in the transverse direction T from the bottom scores  145 ,  245  to the top scores  143 ,  243  may be slightly smaller than the distance from the filter media bottom  233  to the filter media top  231 , thus filter media  130  may be oversized in the transverse direction T relative to the frame members  110 ,  240 . This oversizing allows a friction fit between the filter media  130  and the frame  105  when the front attachment members  142 ,  144 ,  146 ,  148  are folded and attached to the rear attachment members  242 ,  244 ,  246 ,  248 , securing the filter media  130  in place relative to the frame  105 . Additionally, adhesives may be applied to any or all of the filter media top, bottom, and sides  231 ,  233 ,  235 ,  237  and/or the attachment members  142 ,  242 ,  144 ,  244 ,  146 ,  246 ,  148 ,  248  to aid in securing the filter media  130  to the frame  130 . Stretching the frame  105  in the transverse direction T creates tension in the frame  105  in the same direction. The tensile support members  155 ,  156 ,  255 ,  256  are oriented parallel to this tension to help the frame  105  better withstand the tension and resist deformation. 
     Referring now to  FIGS. 3A and 3B , air filters  300 ,  400  are often used side-by-side in operation as depicted. Air filters  300  without tensile support members may be deformed by excessive tension in the frame resulting from the compression of the filter media  130 . This deformation creates outward bowing of frame top and bottom side members  312 ,  314  in the transverse direction T. Angular support members  352  consequently are pulled outward in the transverse direction T and the resulting tension in the angular support members  352  pulls inwardly in the machine direction M on frame first and second side members  316 ,  318 . The bowing depicted in  FIG. 3  is not to scale, and is exaggerated to help illustrate the bowing problem. This bowing creates gaps  311 ,  321 ,  331 ,  341  through which air or other fluids may pass substantially unfiltered, thus diminishing the filtering capability of the air filters  300  tensile support members, especially when multiple are used side-by side. The tensile support members  157 ,  158  of the air filters  400  reduce the bowing by alleviating some of the tension from the angled support members  152 . Reducing the amount of tension in the transverse direction T imposed on the angled support members  152  consequently reduces the amount of tension translated to the first and second side members  116 ,  118 , thus reducing or diminishing the existence of gaps and improving the filtering efficiency when utilizing the air filters  400  with tensile support members  157 ,  158 , especially when multiple are used side-by-side. 
     Referring now to  FIGS. 1-3 , a variety of support member  152 ,  252 ,  155 ,  156 ,  157 ,  158 ,  255 ,  256  patterns and/or orientations are depicted.  FIG. 1  illustrates an embodiment having one tensile support member  155  extending in the transverse direction T and located approximately equidistantly from frame first side member  116  and frame second side member  118 .  FIG. 2  illustrates an embodiment having two tensile support members  155 ,  156 ,  255 ,  256  on each of the frame front  110  and frame rear  240 ; one extending in the transverse direction T and located approximately equidistantly from frame first side members  116 ,  246  and frame second side members  118 ,  248 , and the other extending in the machine direction M and located approximately equidistantly from frame top members  112 ,  242  and frame bottom members  114 ,  244 .  FIG. 3  illustrates an embodiment of the air filter  400  having two tensile support members  157 ,  158  extending in the transverse direction T, each located equidistantly from the first or second side members  116 ,  118 , respectively, although it is understood that they not be equidistantly located from side members  116 ,  118 . These are three examples of possible arrangements of tensile support members  155 ,  156 ,  157 ,  158 ,  255 ,  256  and it is understood that any of a variety of orientations may be used, including, but not limited to, using more or fewer tensile support members or changing the spacing of the tensile support members  155 ,  156 ,  157 ,  158 ,  255 ,  256 ; and it is further understood that the tensile support members  155 ,  156 ,  157 ,  158 ,  255 ,  256  may be other than substantially straight members as depicted in  FIGS. 1-3 . It is generally understood in the art that any material covering the flow passage may result in an increased pressure drop, thus it may be desirable to use relatively little material and/or relatively few tensile support members  155 ,  156 ,  157 ,  158 ,  255 ,  256 , which may obstruct an air flow F or flow of other fluids through the air filter  100 ,  200 ,  400 . However, it may be desirable to have one or more tensile support members  155 ,  156 ,  157 ,  158 ,  255 ,  256  extending in the transverse direction T and also one or more tensile support members  155 ,  156 ,  157 ,  158 ,  255 ,  256  extending in the machine direction M to facilitate assembly, as shown in  FIG. 2 . Including one or more tensile support members in each of the transverse direction T and the machine direction M may help avoid misaligning the tensile support members  155 ,  156 ,  255 ,  256  in relation to the tension in the frame  105 . Although  FIGS. 1-3  illustrate angled support members  152 ,  252  oriented approximately 45 degrees from the transverse direction T and/or the machine direction M, it is understood that the angled support members  152 ,  252  may be oriented at any of a variety of angles, and that each angled support member  152 ,  252  may be oriented at an angle different from the orientation of any other angled support member  152 ,  252 . Further, it may be desirable to form some or all of the support members  152 ,  252 ,  155 ,  156 ,  157 ,  158 ,  255 ,  256  from a diecut and/or to form the frame members  110 ,  240  from the same or similar diecut, whereby the diecut may also include front attachment members  142 ,  144 ,  146 ,  148  and/or rear attachment members  242 ,  244 ,  246 ,  248 , to reduce manufacturing and tooling costs. However, it is understood that frame front  110  and frame rear  240  need not be identical or similar, and that each may be made from a different diecut. It is also understood that one of frame front  110  and frame rear  240  may be without support members  152 ,  252 ,  155 ,  156 ,  157 ,  158 ,  255 ,  256 . An embodiment of the air filter  100 ,  200 ,  400  may include a front frame  110  and a rear frame  240  that are have different inner and/or outer perimeters, for example, where the frame  105  employs a “pizza box” design. A pizza box design may facilitate assembly of the frame  105  when, for example, front frame  110  has a larger width in both the transverse direction T and the machine direction M than rear frame  240 , and therefore may envelope rear frame  240  including rear attachment members  242 ,  244 ,  246 ,  248 , wherein rear attachment members  242 ,  244 ,  246 ,  248  have been folded about rear scores  243 ,  245 ,  247 ,  249 . Thus, the front frame  110 , in this example, may overlap the rear frame  240  because the front frame  110  has a larger width in both the machine direction M and the transverse direction T. It is understood that the pizza box design may alternatively be employed by instead having the rear frame  240  overlap the front frame  110  by having the rear frame  240  have a larger width in both the machine direction M and the transverse direction T. A primary advantage of the “pizza box” design is that it reduces stress on the attachment members  142 ,  242 ,  144 ,  244 ,  146 ,  246 ,  148 ,  248 . A primary disadvantage of the “pizza box” design is that it requires extra tooling and extra parts to make the different size diecuts. 
     Referring again to  FIGS. 1-3 , polyester or polyethylene fibers may be used to construct the filter media  130 . These fibers may be virgin and/or be nonwoven. In some embodiments, it may be desirable to construct the filter media  130  from materials having enhanced operating characteristics. For example, polyester and/or polyethylene virgin fibers may be used to form a web used to construct the filter media  130 . Filter media constructed of webs of polyester and/or polyethylene virgin fibers have longer life and improved consistency than other materials commonly used in the art, such as, for example, cotton-polyester fiber blends. For example, test data has shown that polyester and/or polyethylene virgin fiber filter media, having a weight of 7-14 grams per square foot and a thickness of 100-200 mils, has a higher and more consistent dust holding capacity (195 grams±20) than does a cotton-polyester blend of the same weight and thickness (120 grams±40). However, polyester and/or polyethylene virgin fiber webs may have a stiffness of at least about 600 Gurley or more, and thus can be stiffer than cotton-polyester blends. As used herein, the phrase “stiffness of at least about 600 Gurley” is understood to include stiffness of somewhat less than 600 Gurley, including 500 Gurley. It is further understood that, although reference is made to polyester and polyethylene virgin fibers, fibers other than virgin may be used. It is understood however, that any of a variety of materials may be used to construct the filter media and such materials are known to those having ordinary skill in the art. Further, the frame  105  and its component members disclosed herein may be constructed of cardboard, beverage board, paper, plastic, wood, metal, fiberglass, or any other material. 
     Referring again to  FIGS. 1-3 , the embodiments depicted of the air filter  100 ,  200 ,  400  may be formed and assembled by forming the frame front  110  and the frame rear  240  with one or more diecuts containing the desired configuration of the support members  152 ,  252 ,  155 ,  156 ,  157 ,  158 ,  255 ,  256  as well as the desired configuration of the attachment members  142 ,  144 ,  146 ,  148 ,  242 ,  244 ,  246 ,  248 . An adhering portion of the frame rear  240  that will be adjacent to the filter media  130  is coated with an adhesive or similar material or device. The plurality of pleat tips  232  of filter media  130  is then aligned with the frame rear  240  as desired and brought into contact with the adhering portion thereof. An adhering portion of the frame front  110  or the frame rear  240  is coated with an adhesive or similar material or device, aligned with the filter media  130  as desired, and brought into contact with the plurality of pleat tips  132 . An attachment portion of any or all of the attachment members  142 ,  144 ,  146 ,  148 ,  242 ,  244 ,  246 ,  248 , wherein the attachment portion is on the side proximate the filtering media  130 , are also coated with an adhesive or similar material or device. One adhesive demonstrating advantageous water resistance and wet tack properties is SDX-12-V8, a synthetic multi-polymer emulsion designed especially for the air filter industry. Thus, SDX-12-V8 or similar adhesives may be desirable to use for any or all adhesion of the frame  105  and/or filter media  130 . Generally, application rates of between 8 and 12 wet grams per square foot will be sufficient. In any order, one of the top attachment members  142 ,  242 , one of the bottom attachment members  144 ,  244 , one of the first side attachment members  146 ,  246 , and one of the second side attachment members  148 ,  248  may be folded toward the filtering media  130  about the corresponding score  143 ,  243 ,  145 ,  245 ,  147 ,  247 ,  149 ,  249 , respectively, and attached to the filter media  130 . The remaining unfolded attachment members  142 ,  242 ,  144 ,  244 ,  146 ,  246 ,  148 ,  248  may then be folded about the corresponding score  143 ,  243 ,  145 ,  245 ,  147 ,  247 ,  149 ,  249 , respectively and attached to the corresponding attachment member  142 ,  242 ,  144 ,  144 ,  146 ,  246 ,  148 ,  248 . Tension is introduced into the frame  105  when the attachment members  142 ,  242 ,  144 ,  244 ,  146 ,  246 ,  148 ,  248  are attached if the filtering media  130  is longer in the transverse direction T and/or the machine direction M than a distance measured across the inner perimeter of frame  105  in the same direction. 
     The foregoing description of several embodiments of the invention has been presented for purposes of illustration. It is not intended to be exhaustive or to limit the invention to the precise steps and/or forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. It is intended that the scope of the invention and all equivalents be defined by the claims appended hereto.