WO2007047636A1

WO2007047636A1 - Panel filter and panel filter manufacturing process

Info

Publication number: WO2007047636A1
Application number: PCT/US2006/040477
Authority: WO
Inventors: Steven E. Ogle
Original assignee: L & P Property Management Company
Priority date: 2005-10-14
Filing date: 2006-10-16
Publication date: 2007-04-26

Abstract

A panel filter comprises a frame (228) comprising a single piece of frame material (120) forming a peripheral region (124) and an interior region (126) and a nonwoven fiber batt filter media (212, 214) attached to and supported by the frame. A method (100) for manufacturing a panel filter comprises forming a frame (102) having a peripheral region (124) and an interior region (126) from a single piece of frame material (120), coating at least a portion of the frame (120) with an adhesive (104), and applying a filter media to the coated frame (106), the adhesive attaching the filter media to the frame (108) Another method for manufacturing a panel filter comprises forming a frame (102), coating at least a portion of the frame with an adhesive that prevents the coated portion of the frame from oxidizing (104), and attaching a filter media to the frame via the adhesive (106).

Description

Panel Filter and Panel Filter Manufacturing Process

BACKGROUND

[0001] A panel filter is a filter that removes particles from the air in heating, ventilation, and air conditioning (HVAC) systems. Typically, the panel filter comprises an internal frame positioned between two or more layers of filter media. The frame is typically formed from a plurality of galvanized metal pieces that are welded together, and each layer of filter media is comprised of a plurality of fibers formed into a nonwoven fiber batt. Generally, the panel filter is manufactured by forming the frame from a welded combination of a peripheral frame for supporting the peripheral region of the panel filter and a plurality of wire crossbars for supporting the interior region of the panel filter. Then the frame is positioned between two layers of the filter media before attaching the layers of filter media to each other, thereby enclosing the frame therebetween. The panel filter may then be placed in service in an HVAC system. [0002] The frame is the supporting component of the panel filter. First, the frame supports the peripheral region of the panel filter to secure the panel filter within the panel filter housing of the HVAC unit. This prevents the panel filter from being blown out of the housing when air flows therethrough. Second, the frame supports the interior region of the panel filter to prevent buckling when air flows therethrough. [0003] Several problems are inherent in conventional panel filter frames. Specifically, it takes a considerable amount of time to weld the plurality of components of the frame together, which complicates the manufacturing process. Moreover, the wire used to form the frame is typically galvanized, which increases the cost of manufacturing the panel filter, and makes it more difficult to weld the wire frame togetiier. Consequently, a need exists for a panel filter and an associated method of manufacture that eliminates the need to weld and/or galvanize the frame.

SUMMARY

[0004] In one aspect, the disclosure is directed to a panel filter comprising a frame comprising a single piece of frame material forming a peripheral region and an interior region, and a nonwoven fiber batt filter media attached to and supported by the frame.

[0005] In another aspect, the disclosure is directed to a method for manufacturing a panel filter, the method comprising forming a frame having a peripheral region and an interior region from a single piece of frame material, coating at least a portion of the frame

38776.01/4003.19902 with an adhesive, and applying a filter media to the coated frame, the adhesive attaching the filter media to the frame.

[0006] In yet another aspect, the disclosure is directed to a method for manufacturing a panel filter, the method comprising forming a frame, coating at least a portion of the frame with an adhesive that prevents the coated portion of the frame from oxidizing, and attaching a filter media to the frame via the adhesive.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] For a more complete understanding, and for further details and advantages of the panel filter and methods of manufacture disclosed herein, reference is now made to the accompanying drawings, in which:

[0008] FIG. 1 depicts a flow chart of one embodiment of a Panel Filter Manufacturing

Process;

[0009] FIGS. 2 A - 2F schematically depict representative examples of the wire forming aspects of the Panel Filter Manufacturing Process; [0010] FIGS. 3 A - 3F schematically depict representative examples of frames formed by the Panel Filter Manufacturing Process;

[0011] FIGS. 4A - 4F schematically depict representative examples of a manufacturing line that can implement the Panel Filter Manufacturing Process; [0012] FIG. 5 is a plan view of one embodiment of a Panel Filter; and [0013] FIG. 6 is a cross-sectional view of one embodiment of the Panel Filter taken along section line 6-6 of FIG. 5.

DETAILED DESCRIPTION

[0014] The Panel Filter Manufacturing Process disclosed herein is an improved method for manufacturing a panel filter. More specifically, the Panel Filter Manufacturing Process produces a frame for a panel filter that supports both a peripheral region and an interior region of the panel filter. In an embodiment, the frame is made of a single piece of frame material, such as an ungalvanized wire, for example, that is bent into a shape suitable for supporting both the peripheral region and interior region of the panel filter. Various portions of the one-piece, bent wire frame can be attached together using clips or other securement means, thereby further enhancing the frame's ability to support the panel filter. The bent wire frame eliminates the need to weld the peripheral region and the interior region of the frame together. In an embodiment, the frame is formed from an ungalvanized wire, and is coated with an adhesive coating to prevent the metal frame from oxidizing or rusting. FIG. 1 illustrates method 100, one embodiment of the Panel Filter

38776.01/4003.19902 Manufacturing Process, which comprises forming a frame at 102, coating the frame with an adhesive at 104, applying a filter media to the frame at 106, curing the adhesive at 108, and cutting the panel filter at 110. Each of the aforementioned steps is described in further detail below. [0015] The Panel Filter Manufacturing Process begins by forming the frame at 102 of method 100. The frame is formed by bending a single piece of wire into a shape that will both extend around the peripheral region of the panel filter and extend into the interior region of the panel filter. The use of a single wire may significantly reduce the time, capital, and personnel required to form the frame. In addition, the use of a single wire eliminates the need to weld several pieces of wire together to form the frame, thereby reducing the complexity of the manufacturing process. In one aspect, the wire may be fed onto a bending table from a spool of wire via a feeder or a similar apparatus. The bending table contains a plurality of fingers, which may be fixed or movable, that bend the wire as it is fed onto the bending table. For example, the bending table may have one fixed finger and one moveable finger. When the wire is fed between the two fingers, the movable finger can move relative to the fixed finger to bend the wire to a desired angle, such as 30, 45, 60, 90, 120, 135, 150, or 180 degrees, for example. It is fully contemplated that the wire may be bent to any desired angle greater than 0 degrees and up to or including the aforementioned 180 degrees. [0016] One suitable wire is ungalvanized steel wire. Ungalvanized steel wire bends easily, holds a shape once bent, is inexpensive, is readily available, and is. easy to work with. Galvanized steel wire may also be used, but may be less advantageous than ungalvanized steel wire due to the cost of the galvanization process and the difficulty in welding galvanized steel, should welding be required. In addition, the protective zinc coating that results from the galvanization process may be unnecessary because the adhesive used in the Panel Filter Manufacturing Process coats the wire to prevent oxidation of the wire.

[0017] FIGS. 2A, 2B, 2C, and 2D illustrate the process of bending a single wire 120 using a fixed finger 122 and a moveable finger 124 to form a frame having a complex shape in accordance with the forming process described above. For the sake of simplicity and ease of illustration, the bending table 206 depicted in FIG. 2A, on which the fixed finger 122 and the movable finger 124 are supportably mounted, has been omitted from FIGS. 2B - 2D. In FIGS. 2A, 2B, 2C, and 2D, the movable finger 124 travels along a movable finger path 126, which may be a curved slot within the bending table 206 that

38776.01/4003.19902 allows the movable finger 124 to be selectively positioned using a motor, servo, gears, and/or some other drive mechanism (not shown). The frame forming process 102 begins when the wire 120 is fed between the fixed finger 122 and the movable finger 124. When a sufficient amount of wire 120 is fed past the fixed finger 122 (e.g. a length of wire 120 equal to the length of the first leg of the frame to be formed), the movable finger 124 is moved about the fixed finger 122 along the movable finger path 126, thereby bending the wire 120 around the fixed finger 122 until the wire 120 is bent to the desired angle. FIG. 2B shows the wire 120 bent to an angle of 90 degrees. Due to the malleable nature of metal wire, the wire 120 will hold the bent shape when the movable finger 124 is repositioned away from the bent portion of the wire 120.

[0018] The moveable finger 124 may then be returned to its original position, and an additional length of wire 120, generally equal to the length of the next leg of the frame, may then be fed between the movable finger 124 and the fixed finger 122 as depicted in FIG. 2C. The movable finger 124 is then rotated about the fixed finger 122 along the movable finger path 126 to create an additional angle in the wire 120. FIG. 2D shows the wire 120 bent a second time, the second angle also being 90 degrees. As previously stated, persons of ordinary skill in the art will appreciate that the movable finger 124 can be moved in relation to the fixed finger 122 to create angles in the wire 120 other than the angles specifically described and/or illustrated herein. Persons of ordinary skill in the art will also appreciate that a plurality of movable fingers 124 may be employed to create bends in opposite directions than those illustrated in FIGS. 2A, 2B, 2C, and 2D. [0019] As will be more fully described below, the bent wire 120 will form a frame for a panel filter that supports both the peripheral region and the interior region of the panel filter. The peripheral region of the panel filter is defined as is a user-defined percentage of the panel filter area that exists around the perimeter of the panel filter. The user-defined percentage is best selected by a person of ordinary skill in the art based on the specific factors affecting design and use of the panel filter, including the type of fluid to be filtered, the physical properties (e.g. temperature, pressure, density, viscosity, and state) of the fluid to be filtered, whether the fluid to be filtered is a combination of fluids such as a mixture of air and water, the expected service life of the panel filter, and so forth. In embodiments, the peripheral region ranges between about 5 and about 45 percent, between about 10 and about 30 percent, or between about 15 and about 25 percent of the panel filter area. Given the aforementioned definition of the peripheral region, the interior region is defined as that portion of the panel filter that falls within the peripheral region. For example, if the panel

3877601/4003 19902 filter is square in shape, measures ten inches by ten inches, and the user-defined percentage of the peripheral region is 19 percent, then the peripheral region of the panel filter is one- half inch wide and extends around all four sides of the panel filter. The interior region would then be the nine inch by nine inch square area falling within the peripheral region of the panel filter. In the alternative, the interior region may be defined as that portion of the panel filter that does not form part of the peripheral region. Applying this alternative definition, the interior region would be unchanged, hi some configurations, for example, those in which the peripheral region is not co-extensive with an outer edge of the panel filter, the alternative definition of the interior region would be better suited. [0020] hi describing the frame, it may be difficult to determine which portions of the frame fall within the peripheral region of the panel filter and which portions of the frame fall within the interior region of the panel filter prior to the completion of manufacture of the panel filter. Consequently, the frame can be defined as having its own peripheral region and interior region. More specifically, the peripheral region of the frame can be defined as that portion of the frame that lies on the greatest potential rectangular perimeter of the frame formed by the wire. The greatest potential rectangular perimeter of the frame is defined as a rectangular shape with a width dimension equal to the greatest width of the frame and a length dimension equal to the greatest length of the frame. In turn, the interior region is defined as the combination of that portion of the frame falling within the greatest potential rectangular perimeter of the frame occupied by the wire and the open or closed side portion (as hereinbelow defined) of the peripheral region. Finally, the peripheral region is defined as the greatest potential rectangular perimeter of the frame less the interior region and the portion of the frame falling outside of the exteriormost portion of the space occupying the wire. [0021] As an example, a wire 120 may be bent to form a frame 228 that is square in shape with a single crossbar, as shown in FIG. 3B. The peripheral region 124 of the frame 228 is that portion of the wire 120 that occupies the outside square because that portion of the wire 120 lies on the greatest widthwise and lengthwise dimensions of the frame 228. The crossbar extending between the two sides is then defined as the interior portion 126 of the frame 228. As an additional example, the frame 228 may be generally square in shape with an X-shaped interior region 126, as shown in FIG. 3D. The peripheral region 124 of the frame 228 is that portion of the wire 120 that makes up the top and bottom bracket- shaped pieces because that portion of wire 120 lies on the greatest widthwise and lengthwise dimensions of the frame 228. The remaining X-shaped portion of the wire 120

38776.01/4003.19902 is then the interior region 126 of the frame 228. It should be noted that persons of ordinary skill in the art will appreciate that a single wire 120 can be bent such that it occupies at least a portion of both the peripheral region 124 and the interior region 126 of the frame 228. [0022] Frames can also be classified as being closed-sided or open-sided. Closed- sided frames are defined as those frames having wire that completely occupies the greatest potential rectangular perimeter of the frame. FIGS. 3A, 3B and 3C depict examples of closed-sided frames 228. By contrast, open-sided frames are defined as those frames that do not have wire completely occupying the greatest potential rectangular perimeter of the frame. In other words, at least one part of the greatest potential rectangular perimeter of the frame does not contain wire. FIGS. 3D, 3E and 3F are examples of open-sided frames 228.

[0023] As mentioned above, the wire 120 is bent into a complex shape to form a frame 228 that supports both the peripheral region and the interior region of the panel filter. FIGS. 3A, 3B, 3C, 3D, 3E and 3F illustrate six examples of frames 228 suitable for the purposes described herein. FIG. 3 A is an example of a frame 228 with a generally square- shaped peripheral region 124 and a Y-shaped interior region 126. Such a frame 228 is made by first bending a wire 120 to form the Y-shaped interior region 126, then bending the same wire to form a square-shaped peripheral region 124. [0024] FIG. 3B is an example of a frame 228 with a square peripheral region 124 and a single crossbar interior region 126. Such a frame 228 is made by first bending the wire 120 to form the crossbar interior region 126, then bending the same wire 120 to form the square-shaped peripheral region 124. [0025] FIG. 3C is an example of a frame 228 with a square peripheral region 124 and a V-shaped interior region 126. Such a frame 228 is made by first bending a wire 120 to form the V-shaped interior region 126, then bending the same wire 120 to form the square- shaped outer peripheral region 124.

[0026] FIG. 3D is an example of a frame 228 with a peripheral region 124 comprised of first (top) and second (bottom) bracket-shaped portions 136 and an X-shaped interior region 126. Such a frame 228 is made by bending a wire to form half of the top portion 136 of the peripheral region 124, bending the wire 120 so that one of the legs of the X- shaped interior region 126 is formed, bending the wire 120 so that the bottom portion 136 of the peripheral region 124 is formed, bending the wire 120 so that the other leg of the X-

3877601/4003 19902 shaped interior region 126 is formed, and then bending the wire 120 so that the remainder of the top portion 136 of the peripheral region 124 is formed.

[0027] ^• FIG. 3E is an example of a frame 228 with a peripheral region 124 comprised of first (top) and second (bottom) bracket-shaped portions 136 and an hourglass-shaped interior region 126. Such a frame 228 is made in much the same way as a simple square peripheral region 124, but with the wire 120 on the two sides of the outer periphery bent inwards to form an hourglass-shaped interior region 126 and to create the top and bottom bracket-shaped portions 136 comprising the peripheral region 124. [0028] Finally, FIG. 3F is an example of a frame 228 with a peripheral region 124 comprised of first, second, third and fourth L-shaped portions 132 on the corners, and an interior region 126 comprised of first, second, third and fourth generally C-shaped portions 134 on the sides. Such a frame 228 is made in much the same way as a normal square peripheral region, but with the wire bent inwards on all four sides of the outer periphery to form the C-shaped portions 134. Of course, persons of ordinary skill in the art will appreciate that the frames 228 illustrated herein may be made using methods other than those specifically discussed herein. In addition, persons of ordinary skill in the art will appreciate that the orientation of the various components of the interior regions 126 can be altered to optimize the frame 228 for specific applications. Finally, persons of ordinary skill in the art will appreciate that the frames 228 illustrated in FIGS. 3A - 3F are representative examples of frames 228 that are suitable for the Panel Filter Manufacturing Process and that the Panel Filter Manufacturing Process includes frames 228 other than those specifically illustrated herein.

[0029] After the wire 120 is formed into the desired frame shape, such as the shapes shown in FIGS. 3 A - 3F, the ends of the wire 120 are clipped to each other and/or other portions of the frame 228 to secure the frame 228 together. If desired, additional clips may be added to the frame where the interior region 126 contacts the peripheral region 124 of the frame 228. FIGS. 3A - 3F show the location of the clips 130 for the various frame shapes. FIGS. 3A and 3C show clips 130 added to the frame 228 to attach the lower part of the interior region 126 of the frame 228 to the peripheral region 124 of the frame 228. Clips 130 are mechanical fasteners that attach two ends of wire 120 together. Clips 130 are preferable to welds or other attachment methods because they are simple, require little capital equipment to automatically attach to the frame 228, and eliminate the need for welding in the Panel Filter Manufacturing Process. However, it should be clearly understood that the Panel Filter Manufacturing Process further includes an embodiment in

38776.01/4003.19902 which various regions of the single wire frame 228 are attached together using welding, such as spot welding, for example.

[0030] After the frame 228 is formed at 102 of method 100, the frame 228 is coated with an adhesive at 104 of method 100. The adhesive used in the Panel Filter Manufacturing Process performs two functions: it attaches the frame 228 to the filter media and it coats the frame 228 to prevent the wire 120 from oxidizing. Any adhesive material that is suitable for forming a bond between the wire 120 and the filter media material as well as for preventing the frame 228 from oxidizing is suitable for use as the adhesive for the Panel Filter Manufacturing Process. Specific examples of suitable adhesives are high tack hot melt, UV light curable adhesive, and fast drying adhesives, such as cyanoacrylate. The adhesive may be coated onto the frame 228 using any one of a variety of application methods. For example, the frame 228 can be dipped in a vat of the adhesive such that the adhesive coats the frame 228. Alternatively, the adhesive can be sprayed onto the frame 228 until the adhesive coating reaches a predetermined thickness. Further in the alternative, the adhesive can be roller coated onto the frame 228. More specifically, the frame 228 passes over a roller that is continuously coated with the adhesive. As the frame 228 passes over the roller, the adhesive transfers from the roller onto the frame 228, thereby coating the frame 228. In some roller coating applications, the frame 228 is roller coated by passing the frame 228 between a pair of rollers that are each coated with the adhesive.

[0031] After the frame 228 is coated with an adhesive at 104 of method 100, the filter media is applied to the frame at 106 of method 100. Generally, the layers of filter media are stored in roll form such that the rolls of filter media can be unrolled to produce a long piece of filter media. In a repetitive process, upon consumption of a roll of filter media, the end of the roll of filter media can be attached to the beginning of a second roll of filter media to produce an "endless" length of filter media. Two of the "endless" lengths of filter media can then be applied to the frame 228 by positioning the frame 228 on top of one layer of filter media and below another layer of filter media. By repeating the application process for a plurality of frames 228 and then cutting the two layers of filter media between the individual frames 228, a plurality of panel filters can be manufactured in a continuous process.

[0032] Several types of filter media are suitable for use with the Panel Filter Manufacturing Process. One example of a suitable filter media is nonwoven fiber batts. The nonwoven fiber batts used in the Panel Filter Manufacturing Process may be high-loft

38776.01/4003.19902 nonwoven fiber batts or densified nonwoven fiber batts. The fiber composition, density, and manufacturing method of the nonwoven fiber batts can be adjusted to produce a nonwoven fiber batt with suitable airflow and filtration characteristics. One method for manufacturing nonwoven fiber batts suitable for use in the Panel Filter Manufacturing Process is described in U.S. Patent No. 4,753,693 issued June 28, 1988, entitled "Method for Forming a Vacuum Bonded Non- Woven Batt," and hereby incorporated herein by reference as if reproduced in its entirety. Alternatively, the filter media may be polymeric foam, such as polyurethane foam. If the filter media is polymeric foam, then the density, porosity, and manufacturing method of the foam can be adjusted to achieve foam with suitable airflow and filtration characteristics.

[0033] After the filter media is applied to the frame at 106 of method 100, the adhesive is cured at 108 of method 100. The method by which the adhesive is cured is dependent on the specific adhesive chosen for the panel filter. For example, if a heat curable adhesive, such as hot melt, is chosen, then the adhesive is cured using heat. The heat can be applied via a hot air stream passing through the filter media or infrared lamps. Other adhesives, such as UV-curable adhesives, use ultraviolet light to cure the adhesive. For radio frequency (RF) curable adhesives, radio frequency waves are used to cure the adhesive. Some adhesives, such as cyanoacrylate, are self curing in that they do not need an external curing mechanism; they merely cure over time. [0034] After the adhesive is cured at 108 of method 100, the panel filter is cut at 110 of method 100. The panel filters are cut apart from each other at the spaces between the frames 228 to separate the "endless" length of panel filters into individual panel filters. The panel filters may be cut using any cutting device that is acceptable for the filter media. Examples of suitable cutting devices are knives, saws, hot wires, and so forth. [0035] FIGS. 4A - 4F illustrate an apparatus 200 implementing the Panel Filter Manufacturing Process. The apparatus 200 comprises a wire spool 202 and wire feeder 204, a bending table 206, the use of which previously described with respect to FIG. 2A, an adhesive vat 210, a first layer 212 of filter media, a second layer 214 of the same or different filter media, a conveyor 218, a curing device 216, and a knife 220. The apparatus 200 also includes a clip applicator 208 which alternatively may form part of the bending table 206 or may be a discrete component of the apparatus 200. As shown in FIG. 4A, the wire 120 is fed from the wire spool 202, through the wire feeder 204, and onto the bending table 206. While on the bending table 206, the wire 120 is bent into the frame 228 using the fixed finger 122 and the movable finger 124 in the manner previously described with

38776.01/4003.19902 respect to FIGS. 2B-2D. Clips (not shown) may be applied to the frame 228 using the clip applicator 208.

[0036] Turning now to FIG. 4B, the apparatus 200 further comprises a trolley 224 (hidden from view in FIG. 4A) with a plurality of arms 230, and the trolley 224 travels along a track 226. Once the frame 228 is formed, the trolley 224 moves over the frame 228 and picks up the frame 228 using the arms 230. FIG. 4C shows the trolley 224 positioning the frame 228 over the adhesive vat 210, and FIG. 4D shows the trolley 224 dipping the frame 228 into the adhesive in the adhesive vat 210. If desired, the trolley 224 can release the frame 228 so that the adhesive in the adhesive vat 210 completely coats the frame 228. As shown in FIG. 4E, the trolley 224 then removes the frame 228 from the adhesive vat 210, and moves along the frack 226 to reposition the frame 228 over the conveyor 218.

[0037] Referring to FIG. 4F, the trolley 224 then lowers the frame 228 onto the first layer 212 of filter media on the conveyor 218. The first layer 212 of filter media is stored on a roll below the conveyor 218 such that the first layer 212 of filter media can be unrolled onto the top of and travel the length of the conveyor 218. When the frame 228 is placed on the first layer 212 of filter media on the conveyor 218, the frame 228 travels along the conveyor 218 with the first layer 212 of filter media. The second layer 214 of filter media is then positioned on top of the frame 228 and the first layer 212 of filter media. The combination of the first layer 212 of filter media, the frame 228, and the second layer 214 of filter media is then fed into the curing device 216 that cures the adhesive, thereby attaching the frame 228 to the first layer 212 of filter media and the second layer 214 of filter media. If the adhesive is a heat curable adhesive, then the curing device 216 may be an oven or other device that conveys hot air through the combination of the first layer 212 of filter media, the frame 228, and the second layer 214 of filter media. If the adhesive is a light curable adhesive, then the curing device 216 may be an infrared or ultraviolet lamp. If the adhesive is a RF curable adhesive, the curing device 216 may be a series of RF emitters. If the adhesive is a time-curing adhesive, the curing device 216 may be unnecessary. Instead, the conveyor 218 could be lengthened or the speed of the conveyor 218 reduced to allow the adhesive time to cure before the combination of the first layer 212, the frame 228, and the second layer 214 arrive at the knife 220. [0038] After exiting the curing device 216, the combination of the first layer 212 of filter media, the frame 228, and the second layer 214 of filter media continues along the conveyor 218 where a knife 220 cuts between the individual frames 228, thereby

38776.01/4003.19902 JQ producing a plurality of panel filters 222. Of course, a person of ordinary skill in the art will appreciate that the knife 220 may be any cutting apparatus, such as a saw, a hot wire, or any other device suitable for cutting both the layers 212, 214 of filter media and the adhesive-coated wire 120 forming the frame 228. [0039] The apparatus 200 shown in FIGS. 4A - 4F may be modified to obtain alternative configurations. While the embodiment shown in FIGS. 4A - 4F illustrates an apparatus 200 in which a plurality of tasks are integrated into a single unit in series, persons of ordinary skill in the art will appreciate that the individual tasks may be separated and performed by separate equipment. For example, a single unit can be used to form a plurality of frames 228, which may be optionally stored for some period. The frames 228 then may be coated with the adhesive and the filter media 212, 214 applied to the frames 228 to produce the panel filters 222. Similarly, a single unit can be used to form a plurality of pieces of filter media 212, 214 of a predetermined length. Such pieces of filter media 212, 214 can be optionally stored for some period. The frame 228 may then be coated with the adhesive and the pieces of filter media 212, 214 applied to the frame 228 to produce the panel filters 222. Alternatively, one or more of the individual units may be replicated to take advantage of the various speeds of the other units. For example, if a single wire-bending station can produce frames 228 faster than those frames 228 can be coated and the filter media 212, 214 applied, then a single frame bending station can be configured to feed frames 228 to a plurality of stations that coat the frames 228 with adhesive and apply the filter media 212, 214 to the frames 228. Persons of ordinary skill in the art will also appreciate that variations other than those specifically described herein may be within the scope of the present invention. [0040] FIGS. 5 and 6 are plan and cross-sectional views, respectively, of an alternative embodiment of the Panel Filter 222 manufactured according to the Panel Filter Manufacturing Process. The second layer 214 of filter media and the first layer 212 of filter media can be seen enveloping the frame 228. As shown in FIGS. 5 and 6, the frame 228 has a first side surface 227 and a second side surface 229 and is completely retained within the two layers of filter media 212, 214 so that no part of the frame 228 extends outside of the filter media. Unlike prior panel filters, the two layers of filter media 212, 214 are attached to the frame 228, which is coated with an adhesive that prevents the frame 228 from oxidizing. To form the panel filter 222, the apparatus 200 should be modified to include a single layer, specifically layer 212, of filter media and an additional station

38776.01/4003.19902 11 located immediately before the curing station 216 to fold the layer 212 over the side of the frame 228 previously occupied by the layer 214 of filter media.

[0041] m an alternative embodiment, the frame material may be a specialized type of wire, such as flat wire. Flat wire is characterized by its non-uniform, cross-sectional shape in which the height is not equal to the width. Generally, the height of the wire 120 is less than the width such that the flat wire has an increased surface area that contacts the two layers 212, 214 of filter media. Such embodiments are advantageous when manufacturing relatively thin panel filters 222 because the panel filter 222 does not "bulge" in the areas where the frame 228 is located. Alternatively, the height of the wire 120 may be greater than its width, such that the wire 120 penetrates into the two layers 212, 214 of filter media. Such embodiments are advantageous for relatively thick panel filters 222 because the frame 228 penetrates into a greater amount of the filter media, thereby providing additional structural support for the filter media. If desired, the flat wire may also be installed at an angle with respect to the plane of the panel filter 222. [0042] In another embodiment, the frame material may be expanded metal. Expanded metal is stock metal that has been slit and expanded to increase its area without decreasing its structural strength. Generally, expanded metal can be recognized by the distinctive diamond or honeycomb pattern created by the expansion process. When used in the Panel Filter Manufacturing Process, the expanded metal can be cut to the size of the panel filter 222 and used as the frame 228 for the panel filter 222. The expanded metal is advantageous because it supports both the peripheral region and the interior region of the panel filter 222. If desired, various portions of the expanded metal may be trimmed such that the expanded metal frame resembles one or more of the frame shapes depicted in FIGS. 2A-2F. [0043] In another embodiment, the frame material can be wood or a wood composite. Various types and grades of wood and wood composites known within the art are suitable for the present invention. Although wood or wood composites may be bent using the method described above, straight lengths of wood or wood composites may be used and attached together using tacks, staples, nails, screws, or other attachment means. Wood or wood composites may be round in shape or have the flattened shape described above. Variously, it is contemplated that the frame made of the wood or wood composites can be attached to the filter media using the process for attaching a wire frame to the filter media described above or with other processes which may be better suited for bonding wood to a layer of filter media.

38776.01/4003.19902 . « [0044] In yet another embodiment, the frame material may be a polymer, such as polypropylene, polyethylene, polyester, or other polymer or plastic materials, or a resin material, if desired. Such polymer materials are typically extruded from a die head and cooled to form a polymer filament of various cross-sectional diameters. A single relatively large piece of extruded polymer material may be used for the frame 228, if desired. Alternatively, a plurality of the filaments may be combined together to form the frame 228, if desired. Further in the alternative, the polymer material may be molded into the frame shape. Polymer materials are advantageous because they are readily available, inexpensive, easy to work with, and hold a shape once bent. Most polymer materials are thermoplastic in that they are easier to bend when they are heated and hold a bend once cooled. Thus, it is within the scope of the Panel Filter Manufacturing Process that a polymer can be heated at the point at which it needs to bend to aid in the bending of the polymer. If the frame material is a polymer, it is within the scope of the Panel Filter Manufacturing Process that the fixed finger 122 and/or the movable finger 124 shown in FIGS. 2A, 2B, 2C, and 2D may be heated to aid in the bending of the polymer. Persons of ordinary skill in the art will appreciate that the portions of a thermoplastic polymer frame

228 may be heat sealed together in lieu of being clipped or otherwise attached together.

[0045] In another alternative embodiment, the panel filter 222 can be manufactured such that one layer 212 of the filter media is bonded to both the frame 228 and the second layer 214 of filter media, but the second layer 214 of filter media and the frame 220 are not bonded to each other. Such an embodiment can be manufactured by creating the frame 228 and coating the frame 228 with the adhesive as described above, placing the coated frame 228 onto one layer 212 of filter media, and then curing the adhesive. Subsequent to curing the adhesive, the second layer 214 of filter media can then be positioned on the opposite side of the frame 228 from the first layer 212 of filter media. The second layer 214 of filter media can then be attached to the first layer 212 of filter media using any known means of attaching two layers of filter media together. For example, if the filter media are nonwoven fiber batts, then one or both layers of the filter media can contain binder fibers and the two fiber batts can be heated such that they bond with each other. Alternatively, if the filter media is polymeric foam, the two layers of filter media may be attached together using a contact adhesive.

[0046] In yet another embodiment, the panel filter 222 can be manufactured such that the two layers 212, 214 of filter media are bonded to each other and the frame 228 is bonded to the outside of at least one of the two layers 212, 214 of filter media. In such an

38776.01/4003.19902 13 embodiment, the frame 228 may be located on one side or both sides of the layers 212, 214 of filter media. Alternatively, a single layer of filter media can be substituted for the two layers 212, 214 of filter media. If two layers 212, 214 of filter media are used, the panel filter 222 can be manufactured by bonding the two layers 212, 214 of filter media together by spraying, roller coating, or otherwise applying the adhesive to one or both of the two layers 212, 214 of filter media. The two layers 212, 214 of filter media are then contacted together and the adhesive is cured. The frame 228 may then be coated with the adhesive and contacted onto the filter media. The adhesive may then be cured to bond the frame 228 to the filter media. Alternatively, the panel filter 222 can be assembled by applying the adhesive to the two layers 212, 214 of filter media, contacting the two layers 212, 214 of filter media together, applying the adhesive to the frame 228, contacting the frame to the filter media, and simultaneously curing both applications of the adhesive in a single pass through the curing device 216. [0047] While a number of embodiments have been shown and described herein, modifications thereof may be made by one skilled in the art without departing from the spirit and the teachings of the disclosure. The embodiments described herein are exemplary only and are not intended to be limiting. Many variations, combinations, and modifications of the disclosure are possible and are within the scope of the invention. Accordingly, the scope of protection is not limited by the description set out above, but is defined by the claims which follow, that scope including all equivalents of the subject matter of the claims.

38776.01/4003.19902 . .

Claims

1. A panel filter comprising: a frame comprising a single piece of frame material forming a peripheral region and an interior region; and a nonwoven fiber batt filter media attached to and supported by the frame.

2. The panel filter of claim 1 further comprising: a coating covering at least a portion of the frame; wherein the coating prevents the covered portion of the frame from oxidizing.

3. The panel filter of claim 2 wherein the coating attaches the filter media to the frame.

4. The panel filter of claim 1 wherein the frame comprises a first side surface and a second side surface; and wherein a first layer of the filter media is attached to the first side surface of the frame; and a second layer of the filter media is attached to the second side surface of the frame.

5. The panel filter of claim 1 wherein the frame is formed from an ungalvanized metal.

6. The panel filter of claim 1 wherein the frame is formed from a polymer material.

7. A method for manufacturing a panel filter, the method comprising: forming a frame having a peripheral region and an interior region from a single piece of frame material; coating at least a portion of the frame with an adhesive; and applying a filter media to the coated frame, the adhesive attaching the filter media to the frame.

8. The method of claim 7 wherein forming the frame further comprises bending the single piece of frame material into a pre-selected shape using at least one fixed finger and at least one movable finger.

9. The method of claim 7 wherein the adhesive prevents the coated portion of the frame from oxidizing.

10. The method of claim 7 further comprising: curing the adhesive.

11. The method of claim 7 wherein the filter media comprises at least two layers of filter media.

12. The method of claim 7 wherein the filter media is a nonwoven fiber batt.

38776.01/4003.19902 J5

13. The method of claim 7 further comprising clipping the peripheral region of the frame to the interior region of the frame in at least one location.

14. The method of claim 7 wherein the frame is formed from an ungalvanized metal or a polymer material.

15. The method of claim 7 wherein the frame is formed without welding.

16. A panel filter manufactured according to the method of claim 7.

17. A method for manufacturing a panel filter, the method comprising: forming a frame; coating at least a portion of the frame with an adhesive that prevents the coated portion of the frame from oxidizing; attaching a filter media to the frame via the adhesive.

18. The method of claim 17 wherein the frame is formed from a single piece of frame material.

19. The method of claim 18 wherein forming of the frame further comprises bending the single piece of frame material into a pre-selected shape using at least one fixed finger and at least one movable finger.

20. The method of claim 18 wherein the frame comprises a peripheral region and an interior region.

3877601/4003 19902 Jg