Framed air filter and method of making

Abstract

A framed air filter and method of making. The framed air filter includes a pleated air filter and a perimeter support frame that is a channel frame. The channel frame includes two primary frame pieces and two secondary frame pieces. Each of the primary frame pieces has an end that bears a corner tab that includes a sidewall-filling area and an attachment area.

Description

[0001] PA103182W002

[0002] FRAMED AIR FILTER AND METHOD OF MAKING

[0003] Background

[0004] Air filters are commonly used in forced air systems, e.g. residential heating and air- conditioning systems, in order to remove dust and dirt particles and the like.

[0005] Summary

[0006] Herein is disclosed a framed air filter and method of making. The framed air filter comprises a pleated air filter and a perimeter support frame that is a channel frame. The channel frame includes two primary frame pieces and two secondary frame pieces. Each of the primary frame pieces has an end that comprises a comer tab that comprises a sidewall-filling area and an attachment area. These and other aspects of the invention will be apparent from the detailed description below. In no event, however, should this broad summary be constmed to limit the claimable subject matter, whether such subject matter is presented in claims in the application as initially filed or in claims that are amended or otherwise presented in prosecution.

[0007] Brief Description of the Drawings

[0008] FIG. 1 is a perspective view of an exemplary framed air fdter as disclosed herein.

[0009] FIG. 2 is a perspective view of an exemplary pleated air filter suitable for use in a framed air filter as disclosed herein.

[0010] FIG. 3 is a plan view of two exemplary primary frame pieces and two exemplary secondary frame pieces, that can be assembled into a channel frame as disclosed herein.

[0011] FIG. 4 is a magnified plan view of an exemplary secondary frame piece.

[0012] FIG. 5 is a magnified plan view of an exemplary primary frame piece.

[0013] FIG. 6 is a magnified plan view of another exemplary primary frame piece.

[0014] FIG. 7 is a perspective view of an exemplary primary frame piece and an exemplary secondary frame piece being brought together to form a frame comer.

[0015] FIG. 8 is a perspective view of a frame comer formed by the exemplary frame pieces of FIG. 7.

[0016] Like reference numbers in the various figures indicate like elements. Unless otherwise indicated, all figures and drawings in this document are not to scale and are chosen for the purpose of illustrating different embodiments of the invention. In particular the dimensions of the various components are depicted in illustrative terms only, and no relationship between the dimensions of the various components should be inferred from the drawings, unless so indicated.

[0017] Although terms such as “first” and “second” may be used in this disclosure, it should be understood that those terms are used in their relative sense only unless otherwise noted. Terms such as “upward”, “upper”, etc., and “downward”, “lower”, etc., are used for convenience of description, e.g. as describing a framed air filter in a reference position in which the framed air filter is lying flat on a horizontal tabletop. Such terms do not limit the configuration, orientation, etc. in which a framed filter can be used (e.g., an orientation in which the framed air filter is installed in receptacle of a powered air-handling apparatus), and do not limit the orientation in which various items can be held during assembly of the framed air filter.

[0018] Terms such as “outward”, “outwardmost”, “outwardly”, and the like, mean in a direction generally along the overall plane of an air filter away from the geometric center of the air filter. Terms such as “inward”, “inwardmos ’, “inwardly”, and the like, mean in a direction generally along the overall plane of the air filter toward the geometric center of the air filter. The term “overlapping relation” denotes a configuration in which two items overlap each other, and permits at least one additional item (e.g. a layer of adhesive) to be in between the two overlapping item.

[0019] As used herein as a modifier to a property, attribute or relationship, the term “generally”, unless otherwise specifically defined, means that the property, attribute or relationship would be readily recognizable by a person of ordinary skill but without requiring absolute precision or a perfect match (e.g., within + / - 20 % for quantifiable properties; within + / - 20 degrees for angular orientations); the term “substantially”, unless otherwise specifically defined, means to a high degree of approximation (e.g., within + / - 10% for quantifiable properties; within + / - 10 degrees for angular orientations) but again without requiring absolute precision or a perfect match. The term “essentially”, unless otherwise specifically defined, means to a very high degree of approximation (e.g., within plus or minus 2 % for quantifiable properties; within + / - 5 degrees for angular orientations;) it will be understood that the phrase “at least essentially” subsumes the specific case of an “exact” match. However, even an “exact” match, or any other characterization using terms such as e.g. same, equal, identical, uniform, constant, and the like, will be understood to be within the usual tolerances or measuring error applicable to the particular circumstance rather than requiring absolute precision or a perfect match.

[0020] Detailed Description

[0021] Shown in FIG. 1 in perspective view is an exemplary framed air filter 1 as disclosed herein. Framed air filter 1 comprises a pleated air filter 100 with support frame 10 mounted generally on the perimeter of pleated air filter 100. Framed air filter 1 is generally rectangular in shape (which includes square shapes), with pleated air filter 100 likewise being rectangular and with support frame 10 taking the form of a rectangular frame mounted to the perimeter of pleated air filter 100. Framed air filter 1 and the components thereof will comprise an upward-downward axis (which, in use of the framed air filter, will generally correspond to the overall direction of airflow through the filter), indicated as axis “Z” in various Figures. An exemplary pleated air filter 100, suitable for being framed, is shown in isolated perspective view in FIG. 2. Pleated air filter 100 comprises a multiplicity of pleat-panels 113 arranged in a pleated (oppositely -folded) configuration, with an upper side 111 and a lower side 112 (which, in some embodiments, may be similar or identical) and with upper pleat tips 114 and lower pleat tips 115. Pleated air filter 100 comprises first and second opposing primary ends 130 and first and second opposing secondary ends 160. The filter media of which pleated air filter 100 is made is typically sheet-like, with a length and width that are much greater than the local thickness of the air filter media and with an overall planar aspect (disregarding local variations due to the pleating). Pleated air fdter 100 will exhibit a pleat direction (indicated as DPin FIG. 2) that is aligned with the long axes of the pleat tips, and a pleat height (indicated as PH in FIG. 2), which is the distance between nearest-neighbor upper and lower pleat tips 114 and 115 along the upward-downward direction of the framed air filter.

[0022] Support frame 10 is mounted on the perimeter of pleated air filter 100 and comprises two opposing primary portions 13 and two opposing secondary portions 14, the primary and secondary portions meeting at comers 15 of frame 10 and being attached to each other. The primary portions 13 of frame 10 are mounted on the primary ends 130 of pleated air filter 100 and the secondary portions 14 of frame 10 are mounted on the secondary ends 160 of pleated air filter 100. Framed air filter 1, and the components thereof, will comprise a primary axis (“P”, in various Figures) that is parallel to the primary portions 13 of frame 10, and a secondary axis (“S”, in various Figures) that is parallel to the secondary portions 14 of frame 10. Framed air filter 1 and frame 10 will comprise an upper side 11 and a lower side 12 (which designations are again purely for purposes of description).

[0023] By definition, frame 10 is a channel frame, by which is meant a frame whose primary portions and secondary portions each exhibit a generally U-shaped appearance when viewed in cross-section. A frame portion of such a channel frame will generally comprise an outer sidewall (the “base” of the “U”) and an upper flange and a lower flange (the “arms” of the “U”) as evident e.g. in FIG. 7. The outer sidewall will typically be at least generally aligned with the upward- downward direction of the air filter (which will typically correspond to the upstream-downstream direction of the air filter as installed in a powered air-handling apparatus). The primary and secondary ends of pleated air filter 100 will be respectively abutted against inward surfaces of the outer sidewalls of the primary and secondary frame portions (and, e.g., bonded thereto). The upper and lower flanges of each frame portion will be spaced apart (along the above-described upward- downward, “Z” direction) so as to accept perimeter sections of pleated air fdter 100 therebetween. Typically, the upper and lower flanges will be spaced apart a distance that is very similar to the above-described pleat height PH of the pleated air filter 100. (A channel frame will thus be distinguished from a “pinch” frame that is not generally U-shaped but rather has two sloping sidewalls along with upper and lower flanges that are positioned very closely together with a perimeter section of filter media captured (e.g. “pinched”) therebetween.) In various embodiments, perimeter sections of pleated air fdter 100 may be attached, e.g. adhesively bonded, to any or all of the sidewalls, upper flanges, and / or lower flanges, of the frame portions, in order to securely hold the pleated air filter in place within the frame.

[0024] The two opposing primary frame portions 13 of frame 10 will be provided by primary frame pieces 30 (excepting certain segments of the outer sidewall of the primary frame portions, as discussed in detail later herein), and the two opposing secondary frame portions 14 will be provided by secondary frame pieces 60. Exemplary primary frame pieces 30 and secondary frame pieces 60 are shown in plan view in FIG. 3, in an as-manufactured condition (e.g., as made by die-cutting) in which they have not yet been folded along various fold lines to form their three-dimensional, channel, configuration.

[0025] An exemplary secondary frame piece 60 is shown in magnified plan view (with a central portion of frame piece 60 omitted so that the frame ends can be more easily seen) in FIG. 4. Each secondary frame piece 60 comprises an outer sidewall 61, an upper flange 62, and a lower flange 63, that will respectively provide the outer sidewall and upper and lower flanges of a secondary frame portion 14. Fold line 71 (as achieved e.g. by scoring, perforating, etc.) is provided between upper flange 62 and outer sidewall 61, and fold line 72 is likewise provided between lower flange 63 and outer sidewall 61, so that flanges 62 and 63 can be folded (typically, to an angle of 90 degrees with respect to the outer sidewall) to form the channel configuration. Outer sidewall 61 of secondary frame piece 60 will comprise a height (Hs) as indicated in FIG. 4.

[0026] An exemplary primary frame piece 30 is similarly shown in magnified plan view (with a central portion of frame piece 30 omitted so that the frame ends can be more easily seen) in FIG. 5. Again similarly, each primary frame piece 30 comprises an outer sidewall 31, an upper flange 32, and a lower flange 33, that will respectively provide the outer sidewall (exceptions as noted later herein) and upper and lower flanges of a primary frame portion 13. Fold line 37 (again as achieved e.g. by scoring, perforating, etc.) is provided between upper flange 32 and outer sidewall 31, and fold line 38 is likewise provided between lower flange 33 and outer sidewall 31, so that flanges 32 and 33 can be folded (again, to an angle of approximately 90 degrees with respect to the outer sidewall) to form the channel configuration.

[0027] In many embodiments, the outer sidewall and upper and lower flanges of each frame piece will be integral sections of the frame piece, integrally connected to each other at the various fold lines. Ways in which fold lines can be provided by various means of scoring, perforating, and so on, are described in detail e.g. in U.S. Patent 11376537. Outer sidewall 31 of primary frame piece 30 will comprise a height (HP) as indicated in FIG. 5. When the upper and lower primary flanges 32 and 33 are folded as described herein, they will be spaced apart, along the upward-downward (Z) direction, a distance that will be very close to the height Hp of outer primary sidewall 31. In many embodiments, this distance that the primary upper and lower flanges are spaced apart, will closely approximate the previously -described pleat height PH of the pleated air filter 100. The same will hold for the spacing of the secondary upper and lower flanges. In various embodiments, the flange spacing may be a distance that is from at least 90, 95, or 98 %, to 105, or 102 %, of the pleat height PH. (In some embodiments, the perimeter regions of pleated air filter 100 may be installed within the upper and lower flanges in slight compression; the above numbers are thus relative to the average, nominal pleat height of the pleated air filter before being framed.)

[0028] As evident from FIG. 3, the ends of primary frame pieces 30 will be attached to the ends of secondary frame pieces 60 to form frame 10, with the ends of the primary and secondar frame pieces meeting to form frame comers 15. Frame 10 is thus a four-piece channel frame that is assembled by the attaching together of four separate frame pieces. Such a four-piece frame is distinguished from a frame that is formed from a single piece of frame material, and from a frame that is formed from two (e.g. L-shaped) frame pieces. As noted above, in many embodiments each primary frame piece 30 will be an integral structure in which the outer sidewall and upper and lower flanges of the frame piece are integral portions of the frame piece, connected by integral, hinged connections provided by the above-described fold lines; the same will hold for each secondary frame piece 60.

[0029] Each such frame piece may be made of any suitable material, e.g. plastic, metal and so on. In many convenient embodiments, the frame part may be made of cellulosic chipboard (paperboard), of any suitable thickness that provides sufficient mechanical rigidity but that also allows (e.g. when provided with score lines) the ability to form a foldable connection. In various embodiments, such paperboard may range from at least about 16, 18, 20, 22, or 24 thousandths of an inch in thickness, to at most about 36, 34, 32, 30, or 28 thousandths of an inch in thickness. At least one side of the paperboard may comprise a decorative coating or layer if desired. For example, at least a most- easily -visible surface of each frame piece may be rendered white or off-white in appearance, e.g. by coating the appropriate major surface with a white-pigmented layer (e.g., comprising titanium dioxide, barium sulphate, kaolin clay, or like materials). In various embodiments, the frame pieces may be made from a sheetlike piece of chipboard of the general type known as solid bleached board (SBB), solid bleached sulphate (SBS), or clay-coated recycled board (CRB); such materials can typically be obtained with a white surface layer (e.g. a coating) on one or both major surfaces thereof.

[0030] As apparent from inspection of FIG. 3, and in particular FIGS. 4 and 5, primary frame pieces 30 and secondary frame pieces 60 are similar in overall aspect (e.g., both comprise an outer sidewall and upper and lower flanges). The chief difference is that each end 34 of each primary frame piece 30 is equipped with a comer tab 41. Each such comer tab 41 is integrally and hingedly connected, by an integral, hinged connection 42, to an end of the outer primary sidewall 31 of the primary frame piece 30, with this hinged connection 42 providing a fold line that allows comer tab 41 to be rotated relative to outer primary sidewall 31. The ends of the outer secondary sidewalls 61 of secondary frame pieces 60 have no such comer tab; rather, outer secondary sidewalls 61 terminate at edges 65 that do not bear any such tabs as evident in FIG. 4.

[0031] According to the terminology used herein, primary frame pieces are those that bear a comer tab 41 at each end of the frame piece; secondary frame pieces do not bear any such tab. The terminology of other components and relationships (e.g., primary and secondary axes of the framed air filter and so on) arise from this nomenclature. For example, the primary axis (P) of framed air filter 1 and frame 10 is parallel to the long axis of the comer-tab-bearing primary frame pieces 30 (and corresponding frame portions 13), the secondary axis (S) of framed air filter 1 and frame 10 is parallel to the long axis of the non-comer-tab-equipped secondary frame pieces 60 (and corresponding frame portions 14), and so on.

[0032] Comer tabs 41 facilitate the attaching of the ends of primary frame pieces 30 to the ends of secondary frame pieces 60. Referring to FIGS. 7 and 8, with a comer tab 41 folded along integral, hinged connection 42 to an angle of approximately 90 degrees, an attachment area 53 of comer tab 41 of primary frame piece 30 can be attached to a complementary attachment area 66 of outer sidewall 61 of secondary frame piece 60. In many convenient embodiments, this may be performed by disposing an adhesive (e.g. a hot-melt adhesive) on an outward surface 59 of attachment area 53 of comer tab 41, and / or on an inward surface 67 of complementary attachment area 66 of outer sidewall 61 of secondary frame piece 60. The two surfaces, with at least one bearing adhesive, can be brought close together and bonded to form a comer connection of the general type depicted in FIG. 8. Of course, other components may similarly be attached (e.g., overlapping areas of primary and secondary upper flanges, and / or overlapping areas of primary and secondary lower flanges, may be bonded to each other). Although in many embodiments an adhesive such as a hot melt adhesive may be most convenient, any attachment method, e.g. mechanical fastening using staples, may be used in addition, or in place of, the use of adhesive bonding.

[0033] Sidewall-filling areas

[0034] As disclosed herein, a comer tab 41 of a primary frame piece 30 will have another area in addition to the above-described attachment area 53. As visible e.g. in FIG. 5, a comer tab 41 will comprise a sidewall-filling area 43. This sidewall-filling area is proximal to the integral, hinged connection 42 of comer tab 41 to the end of outer primary sidewall 31. (In fact, connection 42 will connect the end of outer primary sidewall 31 to a proximal end of sidewall-filling area 43, as evident from FIG. 5.) The above-described attachment area 53 of comer tab 41 will extend integrally from sidewall-filling area 42 and will be distal from the integral, hinged connection 42 of comer tab 41 to the end of outer primary sidewall 31. (In other words, sidewall-filling area 43 is positioned between attachment area 53 and connection 42.) In many embodiments, the entirety of comer tab 41, including sidewall-filling area 43 and attachment area 53, will be at least generally planar. In such embodiments, attachment area 53 will be an integral, planar extension of sidewall-filling area 43, e.g. that is not connected to sidewall-filling area 43 by a fold line or similar structure. When comer tab 41 is folded along connection 42 in the manner described herein, the entirety of comer tab 41, including attachment area 53 and sidewall-filling area 43, will be oriented at least generally perpendicular to primary sidewall 31 and to upper and lower primary flanges 32 and 33, as evident from FIGS. 7 and 8.

[0035] Sidewall-filling area 43 will comprise upper edge 44 and lower edge 45, as seen e.g. in FIGS. 5 and 8. Edges 44 and 45 will be linear and will be at least substantially parallel to each other (meaning that they are aligned within plus or minus 5 degrees of each other). Edges 44 and 45 will be uniformly spaced apart from each other along the upward-downward (Z) axis of the frame, by which is meant that their spacing will not vary more than 5 % anywhere along their length. Specifically, upper and lower edges 44 and 45 will be uniformly spaced from each other a distance that is at least substantially equal to the upward-downward height (Hp, indicated in FIG. 5) of outer primary sidewall 31 of primary frame piece 30. In this instance, substantially equal means within 5 %.

[0036] In some embodiments, a location at which upper and lower edges 44 and 45 of comer tab 41 cease to have this parallel, uniformly-spaced relationship (e.g., a location at which one or both edges deviate so that the edges become more closely spaced), will denote the end of sidewall-filling area 43. With reference to FIGS. 5 and 7, the location at which upper and lower edges 44 and 45 change direction towards each other (which location is denoted by phantom line 46) is where sidewall-filling area 43 ends and attachment area 53 begins. Location 46 will thus be termed a junction of sidewall-filling area 43 and attachment area 53. The upper and lower edges of attachment area 53 are given reference numbers 57 and 58; in the depicted embodiment of FIG. 5, these upper and lower edges are inwardly tapered so as to approach each other at an end of attachment area 53. In the depicted embodiment of FIG. 5, these upper and lower edges 57 and 58 are symmetrically arcuate. In the depicted embodiment of FIGS. 6-8, these edges are asymmetric, with upper edge 57 being substantially linear and lower edge 58 being arcuate. Such design choices may be made in view of, e.g., the ease of folding the comer tab 41 as affected by the profile of attachment area 53.

[0037] Sidewall-filling area 43 of comer tab 41 plays a key role in the assembling of a primary frame piece 30 and a secondary frame piece 60 to form a frame comer 15. As evident from FIGS. 7 and 8, to form a frame comer, primary frame piece 30 is configured with its upper and lower flanges 32 and 33, and comer tab 41, folded to approximately 90 degree angles as evident in FIG. 8. A secondary frame piece 60 is then brought into position so that at least a portion of an end region 64 of the outer secondary sidewall 61 of the secondary frame piece, is in outwardly overlapping relation with at least a portion of the sidewall-filling area 43 of comer tab 41.

[0038] In some convenient embodiments, this process may be characterized in terms of the position of a terminal edge 65 of end region 64 of outer secondary sidewall 61, in relation to a target 47 of sidewall-filling area 43 of comer tab 41. Target 47 denotes a preselected location at which the terminal edge 65 of end region 64 of outer secondary sidewall 61 will reside, if the primary and secondary frame pieces are exactly in their desired positions. In some embodiments, such a target may not necessarily be marked by any visible indicia on comer tab 41. For example, in the exemplary embodiment of FIG. 7, target 47 is not marked by any visible indicia on the comer tab (target 47 is thus indicated in FIG. 7 by a phantom line). Rather, target 47 is a preselected location that is approximately halfway between the boundaries of the sidewall-filling area 43. (One of these boundaries is hinged connection 42, the other boundary is the above-described junction 46 at which sidewall-filling area 43 ends and attachment area 53 begins.)

[0039] If secondary frame piece 60 is brought into position exactly as described above, the terminal edge 65 of the outer secondary sidewall 61 of secondary frame piece 60 will be exactly atop the target 47 of the sidewall-filling area 43 of comer tab 41. Such an arrangement is shown in FIG. 8, in which terminal edge 65 is superimposed exactly on target 47. In such an arrangement, a subregion 74 of end region 64 of outer secondary sidewall 61 of secondary frame piece 60, is in outwardly overlapping relation with a first sub-area 49 of sidewall-filling area 43 of comer tab 41, as evident from FIGS. 7 and 8.

[0040] In such an arrangement, a second sub-area 48 of sidewall-filling area 43 of comer tab 41 is not overlapped or covered by any portion of outer secondary sidewall 61 of secondary frame piece 60. Thus, in at least some embodiments, this second sub-area 48 serves as part of the externally visible outer secondary sidewall 21 of the secondary frame portion 14. That is, with reference to FIGS. 1 and 8, for a secondary frame portion 14, a major central segment 22 of the outer secondary sidewall 21 of the secondary frame portion is provided by outer secondary sidewall 61 of secondary frame piece 60. At a first end of the secondary frame portion 14, a first minor end segment 23 of outer secondary sidewall 21 of secondary frame portion 14 is provided by a first sub-area 48 of a first sidewall-filling area 43 of a first comer tab 41, as indicated in FIG. 8. Similarly, at a second, opposing end of the secondary frame portion 14, a second minor end segment is provided by a similar, second sub-area of a second sidewall-filling area of a second comer tab (not visible in the viewing perspective of FIG. 8). These first and second minor end segments 23 of secondary outward sidewall 21 of secondary frame portion 14 are visible in FIG. 1.

[0041] Thus, in at least some embodiments, at least a sub-area 48 of the above-described sidewallfilling area 43 may provide, i.e. serve as, an externally visible segment 23 of an outer secondary sidewall 21 of a secondary frame portion 14. This why area 43 is termed a “sidewall-filling” area. This is also why language is used herein to the effect that a secondary frame portion 14 may be substantially (rather than e.g. completely) provided by a secondary frame portion 60, since a minor part of the frame portion may be provided by a sidewall-filling area 43 of a comer tab 41 of a primary frame piece 30.

[0042] In such arrangements, the visible outer secondary sidewall 21 of the secondary frame portion 14 is actually a composite, with a major segment of the sidewall being provided by the sidewall of the secondary frame piece and with two minor segments being provided by first and second comer tabs of the primary frame pieces to which the secondary frame piece is attached. The specific amount of sidewall-filling area 43 that serves as such as sub-area 48 may vary depending on factors in the frame assembly as discussed below; the entirety of area 43 is thus denoted as a sidewall-filling area 43 even though, in some circumstances, only a sub-area 48 may actually perform this sidewall-filling function.

[0043] In the depicted arrangement as visible in FIG. 8, the upper edge 44 of sub-area 48 of sidewall-filling area 43 closely abuts a lateral edge portion 35 of upper flange 32 of primary frame piece 30. Similarly, the lower edge 45 of sub-area 48 closely abuts a lateral edge portion 36 of lower flange 33 of primary frame piece 30, as indicated in FIG. 7. The presence of sub-area 48, the fact that it fills the entirety of a sidewall area that would otherwise not be present, and the fact that its upper and lower edges closely abut complementary linear edge portions of the upper and lower flanges, provide that no significant air leaks will be present in areas of the outer secondary sidewall 14 that are not provided by the outer secondary sidewall 61 of the secondary frame piece 60.

[0044] The advantages offered by the above arrangements are as follows. In assembly of framed air filters, e.g. using automated, high-speed assembly lines, there will inevitably be some statistical variation in the placement of frame pieces relative to one another. With many conventional frame designs (e.g. using comer tabs not configured in the manner disclosed herein), there is a fine line between a secondary frame piece being positioned short of its intended target placement, such that a gap is present between sidewall portions that results in a significant air leak in the framed filter; and, the secondary frame piece being positioned too far forward of its intended target placement, so that the end of the secondary frame piece juts out in cantilevered, protruding fashion past the primary frame piece, and is thus unsightly and susceptible to snagging. Tolerance zone

[0045] The use of a comer tab that has a sidewall-filling area 43 as disclosed herein can allow increased tolerance in the positioning of secondary and primary frame pieces, without introducing air leaks or unsightly configurations. Thus for example, the exemplary arrangement of FIGS. 7 and 8 uses on a target 47 that is approximately halfway along the “span” 51 of sidewall-filling area 43. (Again, this “span” 51 is the dimension of sidewall-filling area from hinged connection 42 to junction 46.)

[0046] A frame-assembly process may be operated so as to target an arrangement in which the terminal edge 65 of the secondary frame piece 60 exactly coincides with the target 47 of the sidewallfilling area 43, as in FIG. 8. However, the herein-disclosed arrangements allow variation in the placement of the secondary frame piece relative to the primary frame piece. This allowed variation will be along the secondary axis “S” as denoted in FIGS. 7 and 8. Variation in the “S'” direction (as denoted in FIGS. 7 and 8) will result in the terminal edge 65 of secondary frame piece 60 falling short (to the left, in FIG. 8) of the target 47. The resulting sub-area 49 of sidewall-filling area 43 that is overlapped by sub-region 74 of end region 64 of secondary frame piece 60 will thus be smaller, and the resulting sub-area 48 that is exposed so as to serve as a minor end segment 23 of the outer secondary sidewall 21 of the secondary frame portion 14, will be larger (in comparison to the arrangement shown in FIG. 8). Whatever their relative size, both the overlapped sub-area 49, and the exposed sub-area 48, will typically be at least generally rectangular in shape.

[0047] An above circumstance, in which the terminal edge 65 of secondary frame piece 60 falls short (in the “S'” direction) of target 47, will not cause any problem; in particular, it will not result in any significant air leaks. Variation in the “S+” direction (again as denoted in FIGS. 7 and 8) will result in the terminal edge 65 of secondary frame piece 60 being positioned beyond (to the right, in FIG. 8) target 47. The resulting sub-area 49 of sidewall-filling area 43 that is overlapped by subregion 74 of end region 64 of secondary frame piece 60 will thus be larger, and the resulting subarea 48 that is exposed so as to serve as a minor end segment 23 of the outer secondary sidewall 21 of the secondary frame portion 14, will be smaller (again, in comparison to the arrangement shown in FIG. 8). However, as long as the terminal edge 65 of secondary frame piece 60 does not go beyond the hinged connection 42 of comer tab 41 to primary frame piece 30, no problems will result; in particular, the arrangement will not be unsightly or susceptible to snagging.

[0048] The use of a comer tab 41 that includes a sidewall-filling area 43 as disclosed herein, can thus allow a frame-piece-placing process to have a “tolerance” zone that generally corresponds to the above-described “span” denoted by reference number 51 in FIGS. 7 and 8. As long as the terminal edge 65 of the secondary frame piece lands somewhere within this tolerance zone 51, the resulting comer will be satisfactory in both function and appearance. Such a tolerance zone can thus, e.g., allow automated frame assembly to be performed at a higher speed without any resulting deficiency in the resulting framed filters.

[0049] The herein-described arrangements, allowing tolerance in the placement of a secondary frame piece along a secondary axis “S”, will not unacceptably affect the total length of the framed air filter along the secondary axis. Rather, in many embodiments a pleated air filter 100 will be produced by taking a partially-framed pleatpack that has primary frame pieces 30 attached to both of its primary ends 130, and bringing secondary frame pieces into position and attaching them to the primary frame pieces, as discussed in detail later herein. A secondary frame piece may be positioned so that at a first end of the secondary frame piece, a first terminal edge 65 of the secondary frame piece is positioned slightly past its target 47 (i.e., in the S+direction). If this is the case, then at the opposite, second end of the secondary frame piece, the second terminal edge 65 of the secondary frame piece will necessarily be positioned slightly short of its target 47 (i.e., in the S' direction). In the resulting secondary frame portion, the two ends of the frame portion will differ in the size of their respective overlapped sub-areas 49 and exposed, sidewall-filling sub-areas 48, but the overall length of the secondary frame portion will be the same. In reference to the framed filter of FIG. 1, the two visible minor end segments 23 that are provided by comer tabs may differ in size, but the overall length (L’s) of the secondary frame portion 14 will not be affected.

[0050] The arrangements disclosed herein establish defined relationships between the length of the frame portions of the framed air fdter, and the length of the outer sidewalls of the corresponding frame pieces from which the framed air filter is made. Specifically, the length of each primary frame portion 13 (denoted as L’Pin FIG. 1) will essentially correspond to the length of the outer primary sidewall 31 of each primary frame piece 30 (denoted as LPin FIG. 3), disregarding the small effects resulting from the thickness of the frame pieces themselves. The length of each secondary frame portion 14 (denoted as L’s in FIG. 1), again disregarding the small effects resulting from the thickness of the frame pieces, will be the length of the outer secondary sidewall 61 of the secondary frame piece 60 (denoted as Ls in FIG. 3), plus the length of the two minor end segments 23 that are contributed by the sidewall-filling sub-areas 48 of the comer tabs of the primary frame pieces.

[0051] Thus, according to the arrangements disclosed herein, secondary frame pieces 60 can be manufactured so that the length of their outer secondary sidewalls 61 is somewhat less than the target length of the secondary frame portions 14 of the resulting framed air filter, noting in passing that the target length of the frame portions may be slightly less than the “nominal” (nameplate) dimensions of the framed air filter. (For example, a framed filter of a nominal 16 x 24 x 4 inch size, may actually be sized e.g. 15.75 x 23.75 x 3.75 inches, as is commonplace with framed air filters.)

[0052] As noted, in some embodiments target 47 may not be indicated by any actual indicia. Rather, it may be a prechosen (but unmarked) location, with the assembly equipment being configured to bring the secondary frame piece into position relative to the primary frame piece so that, ideally, the terminal edge 65 of the secondary frame piece is aligned with the target of the primary frame piece. (However, in actuality, for any given framed air filter, the terminal edge 65 of the secondary frame piece may be located anywhere within the above-discussed tolerance zone surrounding target 47.)

[0053] In some embodiments, target 47 may be denoted by a visible indicia, e.g. if a machine-vision system is used to guide the frame assembly process. Of course, any such indicia need not necessarily be placed exactly at target 47; rather, a set of indicia may be provided anywhere on primary frame piece 30 and / or on secondary frame piece 60, e.g. so that when the indicia are properly aligned or otherwise positioned, the result will be that terminal edge 65 of the secondary frame piece will be aligned with target 47 of the primary frame piece.

[0054] Target 47 can be positioned at any desired prechosen location within sidewall-filling area 53. For example, it can be positioned at any desired location along the above-described “span” of sidewall-filling area 53. As noted, in the exemplary embodiment depicted in FIGS. 7 and 8, target 47 is located approximately halfway along this span. This may be suitable in many instances. However, in some cases target 47 may be located closer to hinged connection 42 of sidewall-filling area 53 with outer primary sidewall 31; or, it may be located close to the junction 46 of sidewallfilling are 53 with attachment area 53. This may be preferable e.g. if the frame-piece-positioning apparatus is configured so as to have tighter control e.g. with regard to deviations in the S+direction than it has with regard to deviations in the S' direction, or vice versa.

[0055] It is noted in passing that it might seem simple to use a frame-assembly fixture or jig that provides a hard stop in the S+ / S' direction so that the terminal edge 65 of the secondary frame piece 60 cannot go past the sidewall-comer provided by hinged connection 42. However, in many highspeed, automated frame-assembly processes (as discussed later herein), a partially -framed pleatpack having two opposing primary frame pieces 30 mounted on primary ends thereof will be continuously moving along its secondary axis “S” during the time that two opposing secondary frame pieces 60 are brought in and attached to the partially-framed pleatpack. Furthermore, during this time, the two opposing secondary frame pieces 60 may likewise be independently moving along this secondary axis “S” as they are moved inward along the “P” axis so as to come into contact with the partially- framed pleatpack. This being the case, in actual practice it can be difficult to arrange a fixture so as to provide a hard stop for the secondary frame pieces at exact, specified locations along the S+ / S' direction.

[0056] The exemplary arrangements presented herein are configured so that the terminal edges 65 of the outer secondary sidewalls 61 of secondary frame pieces 60 are uniformly linear along their entire elongate length and are aligned exactly with the upward-downward (“Z”) axis of the resulting frame. Each target 47 of a comer tab 41 of a primary frame piece 30 can thus be considered to be an elongate line that is similarly oriented, as evident in FIG. 7. Such arrangements may be advantageous in allowing the above-described tolerance zone to be as wide (along the “S” direction) as possible. However, in some embodiments, a terminal edge 65 of an outer secondary sidewall 61 may, e.g., exhibit slight local variations (e.g. it may be slightly undulating or otherwise not strictly linear), and / or it may exhibit an overall axis that is not exactly aligned with the upward-downward, “Z” axis. In such instances, a target 47 may be considered to be shaped so as to be complementary to the terminal edge 65 (noting again that in many instances, target 47 may be an imaginary “line”, location, etc., rather than comprising any kind of indicia).

[0057] Landing zone

[0058] In some embodiments, a landing zone can be established within the overall limits of the above-described tolerance zone 51. This landing zone can be established in view of the statistically- observed tightness or spread that is inherent in the placement of the secondary frame pieces relative to the primary frame pieces, with the frame-assembly apparatus that is used. Thus for example, a landing zone can extend to either side from target 47 (along the “S” axis), a distance chosen so that in assembled filter frames, the terminal edge 65 of the secondary frame piece will be within this landing zone e.g. 80, 90, 95, 98, or 99 % of the time. Thus in various embodiments, in the framed air filter, the terminal edge 65 of the secondary frame piece will be positioned at a distance from target 47, that is less than 80, 60, 40, or 20 % of the above-described “span” of sidewall-filling area 53. Again, the extent to which any population of framed air filters meets any such criteria, will depend on the statistical variation in frame-piece positioning that is exhibited by the particular frameassembly apparatus that is used.

[0059] In some instances, a secondary frame piece may be positioned so that the terminal edge 65 of the secondary frame piece is aligned with the “comer” provided by the hinged connection 42 of the comer tab 41 to the outer sidewall 31 of primary frame piece 30. In such a case, essentially the entirety of the sidewall-filling area 43 of comer tab 41 may be overlapped by end region 64 of the outer sidewall 61 of secondary frame piece 30. In other words, the overlapped sub-area 49 will occupy essentially the entirety of sidewall-filling area 43 with essentially no exposed / visible sidewall-filling area 48 being present. This will still fall within the disclosures herein, as a special case.

[0060] These arrangements can be characterized in terms of imaginary lines 68 and 69 of outer secondary sidewall 61 as shown in FIG. 7. Imaginary line 69, in particular, can be considered to approximately denote the boundary between the outer sidewall’s “end” region 64 that is configured to potentially overlap a portion of the sidewall-filling area 43 of the comer tab, and the outer sidewall’s attachment area 66 that is configured to be attached to attachment area 53 of the comer tab (noting however that in some embodiments, adhesive may be present in end region 64 without adversely affecting the arrangements disclosed herein.)

[0061] With frame pieces of the general type shown in FIG. 7, an arrangement in which the terminal edge 65 of secondary frame piece 60 is aligned with the “comer” provided by the hinged connection 42 of the comer tab 41 to the outer sidewall 31 of primary frame piece 30, will cause imaginary line 68 of end region 64 to align with target 47 of the comer tab. It will also cause imaginary line 69 of end region 64 to align with junction 46 of sidewall-filling area 43 and attachment area 53. This arrangement represents one end of the above-described tolerance zone, i.e., an arrangement in which secondary frame piece 60 is positioned as far in the S+direction as is permitted.

[0062] Conversely, if the frame pieces are positioned so as to be at the other end of the tolerance zone (i.e., an arrangement in which secondary frame piece 60 is positioned as far in the S' direction as is permitted), the terminal edge 65 of the secondary frame piece will be aligned with junction 46 of sidewall-filling area 43 and attachment area 53. In such a case, essentially none of sidewall-filling area 43 of comer tab 41 will be overlapped by end region 64 of the outer sidewall 61 of secondary frame piece 30. In other words, the exposed / visible sidewall-filling area 48 will occupy essentially the entirety of sidewall-filling area 43 with essentially no overlapped sub-area 49 being present. This will still fall within the disclosures herein, as a special case. Again, such an arrangement represents the opposite end of the above-described tolerance zone, with secondary frame piece 60 being positioned as far in the S' direction as is permitted.

[0063] The arrangements disclosed herein, in which the comer tabs of a primary frame piece each comprise a sidewall-filling area 53, differ from comer tabs of frames in the conventional art. Conventional comer tabs are configured primarily as an aid to attaching the ends of two frame pieces together to form a frame comer; e.g., to serve as adhesive-bearing surfaces. The most that a conventional comer tab can do beyond that role, is to occupy a narrow space exactly at a comer where respective outer sidewalls of two frame pieces meet (usually at a 90 degree angle) and are closely abutted to each other but are not connected to each other. In other words, the most that a conventional comer tab can do is minimize any small air leaks through a slit that, in the absence of the comer tab, would exist exactly (and only) at the frame comer. Framed air filters that use conventional comer tabs configured only to minimize air leaks at the frame comer in this manner, are described e.g. in U.S. Patents 8702829, 8979966, 10744441 and 10921020, and in U.S. Patent Application Publications 2024 / 0181377 and 2024 / 0207769 (noting also that many of these documents disclose pinch frames rather than channel frames).

[0064] Such framed air filters and their comer tabs are distinguished from the framed air filters and comer tabs disclosed herein. Specifically, such a conventional comer tab, as present on a primary frame piece, will not provide a minor end segment of a sidewall of a secondary frame portion in the manner disclosed herein. In particular, the use of such a conventional comer tab will not allow the introduction of higher tolerance in frame piece placement that can enhance high-speed frame assembly in the way enabled by the arrangements disclosed herein.

[0065] In an exemplary process of making a framed air fdter 1 as disclosed herein, a pleated air filter 100 is obtained. In some embodiments, one or more support members 201 (of the general type shown in FIG. 1) may be provided. In some exemplary embodiments, any such members 201 may be applied to the pleat tips, and bonded thereto, while the pleated air filter 100 is still in a continuous format. After this, the stabilized pleated air filter 100 may be cut into discrete pleatpacks.

[0066] Each pleatpack may then be brought to a primary framing station at which first and second primary frame pieces 30 are applied to opposing primary ends 130 of the pleatpack. The primary frame pieces 30 are typically brought to the framing station as a stack of flat blanks and are folded along the previously -described fold lines just prior to, and / or in the act of, positioning the frame piece on the primary end of the pleatpack. The primary frame pieces are attached to the primary ends of the pleatpack in any of the general ways mentioned herein, e.g. by the use of hot-melt adhesive that is disposed on some portion of the inward surface of the outer primary sidewall of the frame piece, and / or on some portion of the inward surface of the upper flange and / or the lower flange of the frame piece. If any such upper and / or lower support members 201 are present, the upper and / or lower flanges of the primary frame pieces may also be bonded to the support members.

[0067] The resulting partially -framed pleatpack, bearing first and second primary frame pieces at the opposing primary ends, is brought to a secondary framing station at which first and second secondary frame pieces 60 are attached to the opposing secondary ends 160 of the pleatpack. In many embodiments, the primary ends of the pleatpack, to which the primary (comer-tab-bearing) frame pieces are attached, will be non-corrugated ends of the pleatpack; and, the secondary ends of the pleatpack, to which the secondary frame pieces are attached, will be corrugated ends (edges) of the pleatpack. (By corrugated is meant exhibiting a generally zigzag appearance when viewed along the pleat direction; the secondary ends 160 of exemplary pleated air filter 100 as shown in FIG. 2, are corrugated ends / edges.)

[0068] Secondary frame pieces 60 are typically brought to the secondary framing station as a stack of flat blanks and are folded along their fold lines just prior to, and / or in the act of, positioning the frame piece on the secondary end of the pleatpack, in similar manner as with the primary frame pieces. Either before arriving at the secondary framing section, or at the secondary framing station, the comer tabs 41 of the primary frame pieces of the partially -framed pleatpack will be folded along hinged connection 42 to approximately their final, folded position (as shown in FIG. 7). Each secondary frame piece is arranged so that the upper and lower flanges 62 and 63 of the secondary frame piece will respectively overlie and underlie the upper and lower flanges 32 and 33 of each of the primary frame piece. The secondary frame piece is brought into position against a secondary end of the partially -framed pleatpack, with the hypothetical goal being that the first and second opposing terminal edges 65 of the secondary frame piece are exactly aligned with the targets 47 of the comer tabs 41 at first and second opposing ends of the primary frame piece. However, as discussed extensively earlier herein, a tolerance zone 51 is provided that allows for some statistical deviation in the placement of the secondary frame piece. The same holds true for the other secondary frame piece when it is applied to the other secondary side of the partially -framed pleatpack (typically, this will happen simultaneously with the application of the first secondary frame piece).

[0069] The secondary frame pieces are attached to the secondary ends of the pleated air filter and / or to the primary frame pieces (typically, both are done) in any of the general ways mentioned herein, e.g. by the use of hot-melt adhesive. As noted, in many high-speed frame-assembly production lines the partially -framed pleatpack, and the secondary frame pieces, may all be continuously moving at least along the “S” direction of the pleatpack, during the time that the secondary frame pieces are brought into position and attached to the pleatpack.

[0070] The profile of a comer tab 41 (in particular, the profile of upper and lower edges 57 and 58 of the attachment area 53 of the comer tab) may affect how easily the comer tab can be folded into its desired position (i.e. the position as shown in FIG. 7) and can be held in that position without interfering with the subsequent placement of the secondary frame pieces. As mentioned earlier, various profiles can be used (as long as they do not affect the functioning of the sidewall-filling portion 43 of the comer tab); two such exemplary profiles are depicted in FIGS. 4 and 5. Similarly, the lateral ends of the upper and / or lower flanges of the primary and / or secondary frame pieces can be profiled for similar purposes. In the depicted embodiment of FIGS. 3, 5 and 6, the lateral edges of upper and lower flanges 32 and 33 of primary frame pieces 30 are beveled (it being desirable to preserve linear edge portions 35 and 36 for the purposes discussed earlier herein). In contrast, the lateral edges of the upper and lower flanges 62 and 63 of secondary frame pieces 60 are not beveled, but rather have a slight uniform, overall slope, as most evident in the plan view of FIG. 4.

[0071] In the exemplary arrangements discussed so far, the attachment area 53 of a comer tab 41 can be distinguished from the sidewall-filling area 43 of the comer tab, by way of the upper and lower edges 44 and 45 of the sidewall-filling area 43 being parallel and uniformly spaced, and the upper and lower edges 57 and 58 of the attachment area 53 being convergent as evident in FIGS. 5- 8. However, in some embodiments, an attachment area 53 may comprise upper and lower edges that are parallel and uniformly spaced, as long as this does not interfere with the ability to fold the comer tab in forming a frame comer. In such cases, the designation as to where the sidewall-filling area 43 ends, and the attachment area 53 begins, can be assigned e.g. in view of the actual locations of the comer tab on which an adhesive is disposed for bonding the tab to a secondary sidewall. Such arrangements fall within the disclosures herein.

[0072] The result of the above operations will be a framed air filter 1 of the general type depicted in FIG. 1. In some embodiments, such framed air filter 1 may be configured so that it can be installed in a receptacle of a powered air-handling system, with either side facing the incoming air. (Again, the terminology of upward and downward sides has been used herein, but this is purely for convenience of description.) In some embodiments, a particular side of the framed air filter will be designated as an “upstream” side, with an opposing side being designated a “downstream” side. For example, if a pleated air fdter 100 comprises a stiffening layer e.g. in the form of a highly air- transmissive wire mesh, the framed air filter may be installed so that the stiffening layer is on the downstream side of the pleated air filter.

[0073] In some embodiments, any support members, e.g. of the general type exemplified by members 201 of FIG. 1, may be present on one side (e.g. a designated “downstream” side) or on both sides of the pleated air filter. In some embodiments, any such support members will be elongate and will each have a long axis that is aligned with the secondary axis of the framed air filter, as is the case for the framed air filter of FIG. 1. In alternative embodiments, one or both sides of the pleated air filter may comprise a single continuous (but highly air-transmissive) support grill (e.g. of the general type depicted in FIG. 1 of U.S. Patent 8979966) rather than comprising multiple separate elongate support members.

[0074] The arrangements disclosed herein may be particularly useful in the manufacture of so- called “deep pleat” framed air filters, e.g. that have a nominal “depth” of approximately 4 inches (noting that many such filters may actually have a pleat height that is slightly less than this). In various embodiments, the arrangements disclosed herein may be used in any framed filters, e.g. those with a nominal “depth” of 1 inch (noting that many filters that have a nominal depth of 1 inch, may actually comprise a pleat height in the range of 0.75 inches).

[0075] In some embodiments, a framed air filter as disclosed herein will be made from exactly two primary frame pieces 30 and two secondary frame pieces 60 and will not include any other frame pieces. In some embodiments, the primary frame pieces will comprise comer tabs 41 of the general type disclosed herein and will not have any other tabs. That is, such a primary frame piece may consist essentially of its outer primary sidewall and upper and lower flanges, and its two comer tabs. In some embodiments, the secondary frame pieces will not comprise any comer tabs or any tabs of any kind or type. That is, such a secondary frame piece may consist essentially of its outer secondary sidewall and its upper and lower flanges.

[0076] Pleated air filter 100 may be made from, or comprise, any suitable air filter media and may be configured to filter (e.g., capture) particles, vapors, or gases, or any combination thereof. Potentially suitable materials may include e.g. organic polymeric nonwoven webs (such as melt blown or spunbond webs, carded webs, wet-laid or air-laid webs, and so on) of synthetic or natural fibers; scrims; woven or knitted materials; foams; fiberglass media; or laminates or composites of two or more materials. A nonwoven organic polymeric web comprised of polyethylene, polypropylene or poly(lactic acid) may be suitable, for example.

[0077] In some embodiments, pleated air filter 100 may have at least one layer that comprises an electret material. By an electret material is meant a material (e.g. an organic polymeric material) that, after a suitable charging processes, exhibits a quasi-permanent electric charge. In some specific embodiments, pleated air filter 100 can be, or comprise, a meltblown nonwoven web (e.g. of the general types disclosed in U.S. Patent 4215682 and U.S. Patent 7989371) or a spunbond nonwoven web, that may include at least some fibers that comprise electrets. Filter media that may be particularly suitable for certain applications includes meltspun, spunbonded webs, e.g. media of the general type described in U.S. Patent Application Publication 20080038976 to Berrigan. Nonwoven webs which may be used as, or as a layer, of, the filter media can be a high loft spunbond web, such as described, for example, in U.S. Patent 8162153. In some embodiments, the filter media can be, or include, a low loft spunbond web, such as those described in U.S. Patent 7947142. In some embodiments, the filter media can be, or include a relofted spunbond web such as described in U.S. Patent 11839845.

[0078] Any such chargeable media can thus be treated or otherwise processed to include charged electret moieties. Any suitable charging method may be used, chosen from e.g. corona charging, hydrocharging, tribocharging, and so on. In some embodiments, a filter media may be formed from pre-charged electret fibers; or, a filter media may be formed (e.g. collected as a nonwoven web and consolidated if desired, or formed into a membrane) and then post-charged. Pleats can be formed in the filter media using various methods and apparatus as are well known in the art, for example those described in U.S. Patents 6740137, 7622063, and 9808753. In particular embodiments, the filter media may comprise, or consist of, a multilayer nonwoven web that comprises a spunbond layer and a meltblown layer, e.g. with both layers comprising electrets. In some such embodiments, the spunbond layer may provide at least some filtration in addition to imparting stiffness that enhances pleatability. In some embodiments, the filter media may comprise a meltblown layer that comprises electrets, along with an uncharged spunbond layer or staple fiber layer (which, in such embodiments, may serve primarily to provide stiffness and pleatability).

[0079] A framed air filter 1 as disclosed herein may be used in any powered air-handling apparatus (equivalently, system) in which moving air, e.g. motivated by a mechanized fan or blower system, is desired to be filtered. Such an air filter thus may find use e.g. in HVAC (heating-ventilating-air- conditioning) systems, room air purifiers, vehicular (e.g. automotive) engine or cabin-air filtration applications, filtration of air in the vicinity of sensitive electronic devices, and so on. In some embodiments, an air fdter as disclosed herein may be configured for use in forced-air H VAC systems such as in residences, offices, commercial buildings, retail establishments, and the like (noting that the term HVAC encompasses systems that perform only heating, only cooling, or both, and that such system are often operable in fan-only mode). ft will be apparent to those skilled in the art that the specific exemplary elements, structures, features, details, configurations, etc., that are disclosed herein can be modified and / or combined in numerous embodiments. All such variations and combinations are contemplated by the inventor as being within the bounds of the conceived invention, not merely those representative designs that were chosen to serve as exemplary illustrations. Thus, the scope of the present invention should not be limited to the specific illustrative structures described herein, but rather extends at least to the structures described by the language of the claims, and the equivalents of those stmctures. Any of the elements that are positively recited in this specification as alternatives may be explicitly included in the claims or excluded from the claims, in any combination as desired. Any of the elements or combinations of elements that are recited in this specification in open-ended language (e.g., comprise and derivatives thereof), are considered to additionally be recited in closed-ended language (e.g., consist and derivatives thereof) and in partially closed-ended language (e.g., consist essentially, and derivatives thereof). Although various theories and possible mechanisms may have been discussed herein, in no event should such discussions serve to limit the claimable subject matter. To the extent that there is any conflict or discrepancy between this specification as written and the disclosure in any document that is incorporated by reference herein but to which no priority is claimed, this specification as written will control.

Claims

What is claimed is:

1. A framed air filter, comprising: a pleated air filter comprising an upward side and a downward side and comprising a generally rectangular perimeter comprising first and second opposing primary ends and first and second opposing secondary ends; a perimeter support frame that is a generally rectangular channel frame comprising four comers and comprising an upward-downward axis, a primary axis and a secondary axis, the channel frame comprising: first and second opposing primary frame portions respectively provided by first and second primary frame pieces, the first and second primary frame pieces being respectively mounted on the first and second primary ends of the pleated air filter, each primary frame piece being generally U-shaped with an outer primary sidewall and upper and lower primary flanges extending inwardly therefrom; and first and second opposing secondary frame portions respectively substantially provided by first and second secondary frame pieces, the first and second secondary frame pieces being respectively mounted on the first and secondary ends of the pleated air filter, each secondary frame piece being generally U-shaped with an outer secondary sidewall and upper and lower secondary flanges extending inwardly therefrom; wherein each primary frame piece comprises first and second ends, each end comprising a comer tab that is connected to an end of an outer primary sidewall of the primary frame piece by an integral, hinged connection, that is at least generally planar, and that is oriented generally perpendicular to the outer primary sidewall and to the upper and lower primary flanges; wherein each comer tab comprises a sidewall-filling area and an attachment area, the sidewall-filling area of the comer tab being proximal to the integral, hinged connection of the comer tab to the end of the outer primary sidewall of the primary frame piece and comprising upper and lower edges that are linear, that are at least substantially parallel to each other, and that are uniformly spaced apart from each other, along the upward-downward axis of the frame, a distance that is at least substantially equal to an upward-downward height of the outer primary sidewall of the primary frame piece.

2. The framed air filter of claim 1 wherein the primary and secondary frame pieces are configured and positioned so that at each of the four comers of the frame, an end region of an outersecondary sidewall of a secondary frame piece is in outwardly overlapping relation with an overlapped sub-area of a sidewall-filling area of a comer tab of a primary frame piece.

3. The framed air filter of claim 2 wherein for each comer tab, the sidewall-filling area comprises a span along the secondary axis of the frame and comprises a target at a predetermined location along the span of the sidewall-filling area, and, wherein a terminal edge of the end region of the outer secondary sidewall of the secondary frame piece is positioned at a distance from the target, along the secondary axis of the frame, that is less than 80 % of the span of the sidewall-filling area.

4. The framed air filter of claim 3 wherein the terminal edge of the end region of the outer secondary sidewall of the secondary frame piece is positioned at a distance from the target, along the secondary axis of the frame, that is less than 40 % of the span of the sidewall-filling area.

5. The framed air filter of claim 1 wherein for each at least one of the secondary frame portions of the frame: a major central segment of the outer secondary sidewall of the secondary frame portion is provided by an outer secondary sidewall of a secondary frame piece; at a first end of the secondary frame portion, a first minor end segment of the outer secondary sidewall is provided by a sidewall-filling sub-area of a sidewall-filling area of a first comer tab of a first primary frame piece; and at a second, opposing end of the secondary frame portion, a second minor end segment of the outer secondary sidewall is provided by a sidewall-filling sub-area of a second comer tab of a second primary frame piece.

6. The framed air filter of claim 5 wherein each of the sidewall-filling sub-areas of the secondary frame portion is visible and exhibits a generally rectangular shape.

7. The framed air filter of claim 5 wherein each of the sidewall-filling sub-areas of the secondary frame portion comprises an upper edge that is closely abutted against a lateral edge of an upper flange of a primary frame piece and comprises a lower edge that is closely abutted against a lateral edge of a lower flange of the primary frame piece.

8. The framed air filter of claim 1 wherein for each comer tab, the attachment area of the comer tab extends integrally from the sidewall-filling area of the comer tab and is distal to the integral, hinged connection of the comer tab to the end of the outer primary sidewall of the primary frame piece; and, wherein each secondary frame piece is attached to a primary frame piece at least by way of an attachment area of the secondary frame piece being attached to the attachment area of the comer tab of the primary frame piece.

9. The framed air filter of claim 8 wherein for each comer tab, the attachment area of the comer tab is inwardly tapered so that upper and lower edges of the attachment area are spaced closer to each other, along the upward-downward axis of the frame, in locations that are distal to the sidewallfilling area from which the attachment area integrally extends, and are spaced farther apart from each other in locations that are proximal to the sidewall-filling area from which the attachment area integrally extends.

10. The framed air filter of claim 8 wherein for each comer tab, the attachment area of the comer tab is attached to the attachment area of the secondary frame piece by way of a hot melt adhesive that adhesively bonds an outward surface of the attachment area of the comer tab to an inward surface of the attachment area of the secondary frame piece.

11. The framed air filter of claim 1 wherein the pleated air filter comprises a pleat height that is aligned with the upward-downward axis of the frame and wherein the upper and lower primary flanges of the primary frame pieces are spaced apart from each other, along the upward-downward direction of the frame, a distance that is from 95 % to 102 % of the pleat height of the pleated air filter, and wherein the upper and lower secondary flanges of the secondary frame pieces are spaced apart from each other, along the upward-downward direction of the frame, a distance that is from 95 % to 102 % of the pleat height of the pleated air filter.

12. The framed air filter of claim 1 wherein the first and second opposing primary ends of the pleated air filter are non-corrugated ends and the first and second opposing secondary ends of the pleated air filter are cormgated ends.

13. The framed air filter of claim 1 wherein the framed air filter comprises at least one downward support member that is adhesively bonded to at least some downward pleat tips of the pleated air filter and that is adhesively bonded to a first lower primary flange of the first primary frame piece and to a second lower primary flange of the second primary frame piece.

14. The framed air filter of claim 13 wherein all of the primary frame pieces and secondary frame pieces, and the at least one downward support member, are made of chipboard.

15. A method of making a framed air filter, the method comprising: attaching first and second primary frame pieces to first and second opposing primary ends of a pleated air filter; wherein each primary frame piece comprises first and second ends, each end comprising a comer tab that is connected to an end of the outer primary sidewall of the primary frame piece by an integral, hinged connection and that is at least generally planar and that comprises a sidewall-filling area and an attachment area; attaching first and second secondary frame pieces to first and second opposing secondary ends of the pleated air filter; and, attaching the first and secondary frame pieces to the first and second primary frame pieces, at least by way of attaching attachment areas of the secondary frame pieces to the respective attachment areas of the comer tabs of the primary frame pieces; wherein for each comer tab, the sidewall-filling area of the comer tab is proximal to the integral, hinged connection of the comer tab to the end of the outer primary sidewall of the primary frame piece and comprises upper and lower edges that are linear, that are at least substantially parallel to each other, and that are uniformly spaced apart from each other, along an upward- downward axis of the frame, a distance that is at least substantially equal to an upward-downward height of an outer primary sidewall of the primary frame piece.

16. The method of claim 15 wherein the first and second primary frame pieces are attached to the first and second opposing ends of the pleated air filter, after which the first and second secondary frame pieces are attached to the first and second opposing secondary ends of the pleated air filter and to the first and second primary frame pieces.

17. The method of claim 16 wherein the pleated air filter with the first and second primary frame pieces attached to the first and second opposing ends thereof, is continuously moving during the time in which the first and second secondary frame pieces are attached to the first and second opposing secondary ends of the pleated air filter and to the first and second primary frame pieces.

18. The method of claim 16 wherein the pleated air filter with the first and second primary frame pieces attached to the first and second opposing ends thereof, is intermittently moving during the time in which the first and second secondary frame pieces are attached to the first and second opposing secondary ends of the pleated air filter and to the first and second primary frame pieces.

19. The method of claim 15 wherein for each comer tab, the sidewall-filling area of the comer tab comprises a span along a secondary axis of the frame and comprises a target at a predetermined location along the span of the sidewall-filling area, and, wherein the secondary frame piece is positioned and attached to the comer tab so that a terminal edge of an end region of an outer secondary sidewall of the secondary frame piece is positioned at a distance from the target, along the secondary axis of the frame, that is less than 80 % of the span of the sidewall-filling area.

20. The method of claim 19 wherein the target is an imaginary line that is not marked by any visible indicia of the sidewall-filling area of the comer tab, and wherein the imaginary target is located within plus or minus 20 % of a centerline of the sidewall-filling area of the comer tab.

21. The method of claim 15 wherein the primary and secondary frame pieces are positioned and attached to each other so that at each of four comers of the frame, an end region of an outer secondary sidewall of the secondary frame piece is in outwardly overlapping relation with an overlapped subarea of the sidewall-filling area of the comer tab of the primary frame piece.

22. The method of claim 21 wherein the primary and secondary frame pieces are positioned and attached to each other so that for each secondary frame portion of the resulting frame: a major central segment of an outer secondary sidewall of the secondary frame portion is provided by an outer secondary sidewall of a secondary frame piece; at a first end of the secondary frame portion, a first minor end segment of the outer secondary sidewall is provided by a sidewall-filling sub-area of a sidewall-filling area of a first comer tab of a first primary frame piece; and at a second, opposing end of the secondary frame portion, a second minor end segment of the outer secondary sidewall is provided by a sidewall-filling sub-area of a second comer tab of a second primary frame piece.

Images