Air filter assembly

An air filter assembly is provided which comprises a compressible air pervious multi-sided filter panel and a frame therefor, the latter being adjustable from a collapsed first mode to an operative second mode. The frame of foldable sheet material includes a foraminous center section in supporting engagement with the filter panel; a marginal section delimiting the center section; and a plurality of elongated peripheral sections arranged in alternate pairs and foldably connected to an coacting with the marginal section and with each other to form a hollow verge encompassing the filter panel periphery when the frame is in the second mode. The peripheral sections form a substantially flat multiply flange overlapping and compressing the filter panel periphery when the frame is in the first mode. A first pair of alternate peripheral sections have the opposite end portions thereof overlying corresponding end portions of a second pair of alternate peripheral sections when the frame is in the first mode. When the frame is adjusted from the first mode to the second mode, the overlapped end portions of the second pair of alternate peripheral sections will abuttingly engage at an angle the corresponding end portions of the first pair of alternate peripheral sections and restrain movement of the frame from the second mode to the first mode.

BACKGROUND OF THE INVENTION 
Various types of air filter assemblies have heretofore been utilized; 
however, because of certain inherent design characteristics they have been 
beset with one or more of the following shortcomings: (a) the assembly 
included numerous components and thus was difficult, costly, and awkward 
to assemble; (b) the assembly was inherently weak and required special 
handling; (c) the assemblies could not be effectively compressed together 
so as to form a compact bundle for shipment or storage; and (d) special 
equipment and/or an inordinate amount of manual labor was required to form 
the assembly. 
SUMMARY OF THE INVENTION 
Thus, it is an object of the invention to provide an improved air filter 
assembly which avoids all of the aforenoted shortcomings. 
It is a further object to provide an improved air filter assembly which may 
be readily assembled with high-speed automatic equipment. 
It is a further object to provide an improved air filter assembly having a 
frame which is formed from a single, inexpensive blank of foldable sheet 
material. 
It is a still further object to provide an improved filter assembly having 
a sturdy frame on which a filter panel is mounted and which provides 
minimum obstruction of the air flow through the filter panel. 
Further and additional objects will appear from the description, 
accompanying drawings, and appended claims. 
In accordance with one embodiment of the invention, an improved air filter 
assembly is provided which includes a compressible, air pervious 
multi-sided filter panel, and a frame for supporting the filter panel and 
which is adapted to be manually adjusted from a collapsed first mode to an 
operative second mode. The frame includes a foramious center section on 
which the filter panel is mounted. A marginal section delimits the center 
section and has an inner portion contiguous to the center section and 
secured to peripheral portions of the filter panel. Foldably connected to 
outer portions of the marginal sections are a plurality of peripheral 
sections arranged in alternate pairs. The peripheral sections coact with 
the marginal section and with each other to form a hollow, substantially 
continuous verge which encompasses the filter panel periphery, when the 
frame is in the operative second mode. When the frame is in the collapsed 
first mode, the peripheral sections form a substantially flat multi-ply 
flange which overlaps and compresses the filter panel periphery. While the 
frame is in a collapsed first mode, a first pair of alternate peripheral 
sections is disposed so that the opposite end portions thereof overlie 
corresponding end portions of a second pair of alternate peripheral 
sections. When the frame is manually adjusted from the collapsed first 
mode to the operative second mode, the end portions of the second pair of 
alternate peripheral sections will abuttingly engage at an angle the 
corresponding end portions of the first pair of alternate peripheral 
sections and restrain movement of the frame from the second mode back to 
the first mode.

Referring now to the drawings and more particularly to FIGS. 5 and 7, one 
form of the improved air filter assembly 20 is shown which is adapted to 
be used in forced air heating, ventilating, and air conditioning systems. 
The dimensions of the assembly may vary and will be dictated by the 
configuration of the location of the assembly in the system. 
The assembly 20 comprises only two components; namely, a multi-sided 
compressible filter panel or pad P, and a frame F for supporting the panel 
P. The panel P is of conventional construction and may be formed of any 
one of a number of materials utilized for this purpose. For example, it 
may consist of glass fibers held in a very porous mass by a thermoset 
binder, e.g., phenol formaldehyde solution extended twenty percent with an 
emulsion of VINSOL, a rosin derivative. The surfaces of the panel are 
normally sprayed with a non-drying, non-volatile mineral oil. The filter 
panel P per se forms no part of the invention hereinafter described. 
The frame F is formed from a blank 21 of paperboard material having at 
least the exposed surface thereof treated so as to readily receive printed 
indicia or graphics. The blank, as seen in FIG. 1, includes a foraminous 
center section 22 which is strong enough to support the weight of the 
filter panel P and yet, at the same time will cause minimal resistance to 
the air flowing through the panel P. The shape, size, and relative 
arrangement of the openings 22a formed in the center section 22 may vary 
from that shown, if desired. The center section 22 should be of such 
stiffness that it will be distorted only a neglible amount when subjected 
to the normal air flow through the assembly. 
The blank 21 is also provided with a marginal section 23 which delimits the 
center section 22 and is coplanar therewith. Section 23 is provided with 
an inner portion 23a contiguous to the center section and an outer portion 
23b. The center section 22 approximates the peripheral configuration of 
the filter panel P and normally, at least, portions of the periphery of 
the filter panel P will engage the inner portion 23a of the marginal 
section 23 and will be secured thereto by adhesive H or some other 
suitable means. 
Foldably connected to the outer portion 23b of the marginal section 23 are 
a plurality of peripheral sections 24, 25, 26, and 27 which are arranged 
in alternate pairs with peripheral sections 24, 26 being of substantially 
like configuration and peripheral sections 25, 27 also being of 
substantially like configuration. 
Each section 24, 26 includes a corresponding elongate first panel 24a, 26a 
which is connected by foldline 28 with the outer portion 23b of marginal 
section 23. The first panel 24a, 26a has a length which is substantially 
coextensive with the outer portion 23b to which it is connected. 
Connected by an elongated foldline 30 to first panel 24a, 26a is a second 
panel 24b, 26b. The opposite end edges 24bb, 26bb of the second panel 
converge outwardly and terminate at an elongated foldline 31, the latter 
connecting an elongated third panel 24c, 26c to the second panel. 
The length of panel 24c, 26c is such that a tongue-like projection T 
extends endwise beyond each end of foldline 31. Except for the projections 
T, the end edges 24cc, 26cc converge abruptly outwardly from the 
projections and terminate at an elongated foldline 32 which connects a 
fourth panel 24d, 26d to the third panel. The fourth panel has applied to 
the underside thereof a suitable adhesive, indicated by stippling in FIG. 
1. Foldlines 28, 30, 31, and 32 are disposed in spaced parallel relation. 
As aforementioned, peripheral sections 25, 27 are preferably of like 
configuration and each includes an elongated first panel 25a, 27a which is 
coextensive with the adjacent outer portion 23b of marginal section 23 and 
is connected thereby by foldline 33. Connected by foldline 34 to the 
opposite side of first panel 25a, 27a is an elongated second panel 25b, 
27b. As seen in FIG. 1, the first and second panels are preferably 
coextensive with one another. 
A third panel 25c, 27c which has its opposite ends 25cc, 27cc recessed 
relative to the second panel ends, is connected to panel 25b, 27b by a 
foldline 35. A fourth panel 25d, 27d is connected by foldline 36 to the 
outer edge of third panel 25c, 27c. Second panel 25b, 27b and fourth panel 
25d, 27d are of substantially like configuration. 
When the blank is set up to form the frame F, the undersides of the fourth 
panels 24d, 26d of peripheral sections 24, 26 and the undersides of the 
fourth panels 25d, 27d of peripheral sections 25, 27 are coated with a 
suitable adhesive M or the like. Foldlines 33, 34, 35 and 36 are in 
parallel relation and are disposed transversely of the foldlines 28, 30, 
31, and 32. 
In assembling the air filter assembly 20, the filter panel P is aligned 
with the center section 22 and preferably secured thereto by a suitable 
adhesive H being applied in dots along the periphery of the filter panel 
P, see FIG. 2. In most instances the periphery of the filter panel will 
overlie the inner portion 23a of the marginal section 23. Adhesive M is 
applied to the undersides of the panels 24d, 25d, 26d, and 27d of the 
peripheral section, either before or after the filter panel P is 
positioned on the blank center section 22. 
After the filter panel has been located and the adhesive applied to the 
aforementioned panels of the peripheral section, the third and fourth 
panels 25c, 25d, and 27c, 27d of the peripheral sections 25, 27 are folded 
upwardly and inwardly as units about their respective foldlines 35 and 
assume the folded positions shown in FIG. 3. It will be noted that in such 
folded positions, the adhesively coated surfaces of the fourth panels 25d, 
27d of the respective peripheral sections 25, 27 are facing upwardly. 
Furthermore, it will be noted that the free elongated edges of the fourth 
panels 25d, 27d are spaced from the periphery of the filter panel P. 
Following this step, third and fourth panels 24c, 24d, and 26c, 26d of 
peripheral sections 24, 26 are folded upwardly and inwardly as units about 
foldlines 31 so that the adhesively coated surfaces of fourth panels 24d, 
26d face upwardly. As in the case of coated panels 25d, 27d, the elongated 
free edges of panels 24d, 26d are spaced from the periphery of filter 
panel P. 
Either before or after the third and fourth panels of peripheral sections 
24, 26 have been folded about foldlines 31, as aforedescribed, the 
previously folded peripheral sections 25, 27 are folded upwardly and 
inwardly as units about foldlines 33, so that the adhesively coated 
surfaces of panels 25d, 27d will be adhesively secured to a surface of 
marginal section 23 and at the same time sandwich a peripheral portion of 
filter panel P between the inner portion 23a of the marginal section 23 
and the corresponding fourth panel 25d, 27d. 
Subsequent to peripheral sections 25, 27 being folded, as described, the 
remaining alternate pair of peripheral sections 24, 26 are folded in a 
like manner about their respective foldlines 28. It is important that the 
end portions of the first and second panels 24a, 24b, and 26a, 26b of 
peripheral sections 24, 26 overlie the corresponding end portions of the 
first folded peripheral sections 25, 27 when the frame F initially assumes 
the collapsed first mode I. The importance of this relationship becomes 
apparent when the frame F is manually adjusted from the first mode I (FIG. 
5) to the operative second mode II (FIG. 7). 
As will be noted in FIGS. 8-10, when the frame F is in the second mode, the 
corresponding end portions of the adjacent peripheral sections assume an 
abutting angular relationship and form a closed corner, see FIG. 7, with 
the second panels 24b, 26b overlapping the corresponding second panels 
25b, 27b and thus, creating an attractive miter joint visual effect. 
When the peripheral section end portions are disposed in abutting angular 
relation so as to form the closed corners (FIG. 7), the tongue-like 
projections T formed at the opposite ends of the third panels 24c, 26c of 
peripheral sections 24, 26 extend into pockets formed at the ends of the 
peripheral sections 25, 27 by reason of the recessed ends of third panels 
25c, 27c. With the projections disposed in the pockets, the edges of 
panels 25b, 27b are held in place between the projections T and the 
respective panels 24b, 26b. Thus, the stable corners enhance the overall 
stiffness of the frame. 
As seen in FIGS. 1 and 9, the ends of panel 24c, 26c are undercut at 24cc, 
26cc so as to prevent interference between panels 24c, 26c and panels 25b, 
27b, when the frame F is manually adjusted from the collapsed first mode 
to the operative second mode. 
When the frame is disposed in the collapsed first mode I, as seen in FIG. 
6, an inwardly projecting double-ply flange f is formed by the folded 
second and third panels of each peripheral section. In FIG. 6 only 
peripheral section 24 is shown. It will be noted that the flange f extends 
over a portion of the filter panel P and will compress same, when a 
plurality of the assemblies in a like mode, are stacked and compressed 
together to form a compact bundle, not shown, which is suitable for either 
storage or transporting to a customer a large number of assemblies. 
When manually adjusting the frame from the collapsed first mode I to the 
operative second mode II, the multi-ply flanges f formed by the panels of 
peripheral sections 25, 27 are grasped and moved upwardly and away from 
each other until the third panels 25c, 27c of the peripheral sections 
assume transverse relation with respect to the marginal section 23 and are 
in substantially parallel relation with respect to each other. As the 
peripheral sections 25, 27 are being manually adjusted as described, the 
overlapped end portions of the second panels 25b, 27b will engage the 
overlapping end portions 24b, 26b of peripheral sections 24, 26 and cause 
the latter to simultaneously pivot and the third panels 24c, 26c thereof 
to automatically assume a transverse relation with respect to the marginal 
section 23. As the latter reach this transverse relation, the projections 
T carried at the ends of the third panels 24c, 26c will automatically 
slide under the end portions of the second panels 25b, 27b of peripheral 
sections 25, 27 and capture same between the projections T and the second 
panels 24b, 26b of the peripheral secctions 24, 26, see FIGS. 8-10. 
In the illustrated embodiment, the frame F, when in the second mode, forms 
a substantially continuous hollow (tubelike) verge V which completely 
encompasses the periphery of the filter panel P. The verge is defined by 
the first and third panel of each peripheral section being disposed in 
parallel spaced relation and substantially perpendicular to the plane of 
the marginal section 23, and the second and fourth panels being disposed 
in substantially parallel spaced relation and substantially perpendicular 
to the first and third panels. Where the fourth panels engage and compress 
a portion of the filter panel periphery, the fourth panels might be in a 
slightly non-parallel relation with respect to the corresponding second 
panels. 
The verge V does not interfere with the air flow through the filter panel 
and yet, at the same time, the exposed surfaces of the first and second 
panels and of the marginal section provide desirable areas for printed 
indicia and graphics. The increased stiffness and the relative width of 
the verge significantly facilitates handling of the assembly when the 
latter is being installed in the heating, ventilating, and/or air 
conditioning unit. Furthermore, no tools are required to adjust the frame 
to its operative mode and the assembly, while in the collapsed first mode, 
may be conveniently stored by the customer until it is to be installed. 
When the assembly is being used, the foraminous center section 22 of the 
frame should be disposed on the downstream side of the filter panel, thus, 
deformation of the panel P beyond the plane of the center section 22 by 
reason of the air flow through the panel is, in most instances, eliminated 
or insignificant. The frame prevents the air flow from circumventing the 
filter panel. 
The size, shape, and thickness of the assembly may vary from that shown 
without departing from the scope of the invention herein disclosed and 
claimed.