Reinforced air filters

Abstract

The air filter of the present invention comprises a filter body having a filter medium formed with a fold line along which the filter medium is folded and adjacent inclined walls divided at a top portion connected by the fold line, and cross members fixed to both sides of the inclined walls of the filter medium and extending transversely to the fold line. A method for manufacturing the air filter is also disclosed, which includes the step of placing the filter body within a frame. The cross members formed by hardened adhesive reinforce the air filter against bending deformation due to upstream air pressure.

Description

[Technical Field]

[0001] FIELD OF THE INVENTION The present invention relates to air filters, and more particularly to air filters that are reinforced against harmful bending deformation due to upstream air pressure during use. [Background technology]

[0002] The air filter comprises a filtering structure having a filtering medium with a suitable zigzag filtering structure, i.e., a filter body (filter medium) disposed within a frame, and is used for various air treatments such as heating, ventilation, and air conditioning (HVAC) systems. The air filter, which is disposed transversely to the airflow during use, functions to remove harmful substances from the air passing through the folded filtering medium.

[0003] In an air filter, when high air pressure occurs upstream of an operating air filter, a harmful curved airflow state is formed in the filter body, so that the lateral spacing between the multiple folds or pleats of the filter body on the upstream side is reduced compared to the downstream side, and at the same time, in adjacent curved regions, the fold spacing or pleat spacing of the filter body is increased upstream compared to the downstream side, resulting in an uneven filtering state of the airflow. In the flow state shown in Figures 1A to 1D, the air filter may be further deformed by the high pressure on the upstream side, ultimately reducing its filtering function.

[0004] A known solution to the problem of non-uniform filtering of the filter body is a structure in which reinforcing pieces are fixed to the filter body within the frame to reinforce some of the pleats of the filter body. Although a structure in which a reinforcing piece is placed at the center of the pleats can somewhat reduce the bending force on the filter body caused by the airflow passing through the filter body, there is still a drawback in that the problem of bending deformation of the filter body cannot be solved at the fixing portion of the adjacent reinforcing piece, i.e., between the frame wall and the reinforcing piece. Summary of the Invention [Problem to be solved by the invention]

[0005] There remains a need for an air filter that can withstand bending deformation of the filter body due to airflow pressure during operation while maintaining the desired uniform airflow and filtration efficiency. [Means for solving the problem]

[0006] The present invention relates to an air filter in which an adhesive is applied to a filtration medium during manufacturing, and when the filtration medium is folded to form a filter body, the adhesive applied to the filtration medium bonds to each other to form reinforcing adhesive cross members disposed substantially transversely to the pleats or folds of the folded filtration medium, and to a method for manufacturing the air filter. The adhesive cross members reinforce the folded filtration medium or filter body structure, resist deformation due to air pressure from the upstream side of the air filter manufactured by incorporating the filter body in a frame, and can maintain the air filter in a predetermined appropriate shape.

[0007] An air filter according to an embodiment of the present invention comprises a filtration medium folded along a fold line, a plurality of adjacent inclined walls separated by the tops of the fold line of the filtration medium, and cross members disposed laterally of the fold line and formed on both the front and back sides of the filtration medium.

[0008] In another non-limiting embodiment, the cross members have a curing adhesive. Additionally, in another non-limiting embodiment of the present invention, the cross members have stiffening cross members that extend the entire depth of the filtration media from the upstream apex to the downstream apex. In yet another non-limiting embodiment of the present invention, the cross member comprises a plurality of cross member pieces disposed along a cross member axis and formed between adjacent angled walls of the air filter body.

[0009] In yet another non-limiting embodiment of the present invention, the plurality of cross-member pieces form an arcuate cross-member. In another non-limiting embodiment of the present invention, the arcuate cross member projects upstream of the air filter. In yet another non-limiting embodiment of the present invention, the air filter further comprises a strand of hardening adhesive extending along the top of the filter body.

[0010] In yet another non-limiting embodiment of the present invention, strands of hardening adhesive are placed on both sides of the cross member. In yet another non-limiting embodiment of the present invention, a plurality of cross members are positioned to extend laterally relative to the top of the filter body. Another non-limiting embodiment of the air filter of the present invention further comprises a filter media frame having a sidewall and a filter body mounted within the filter media frame.

[0011] In yet another non-limiting embodiment of the present invention, the filter body is reinforced against deformation due to airflow by cross members extending continuously between each pair of adjacent inclined walls of the filter body.

[0012] Another non-limiting embodiment of a method for manufacturing an air filter according to the present invention includes applying two adhesive lines, a plurality of relatively thin first adhesive lines and at least one relatively thick second adhesive line, to a flat filter media film; folding the flat filter media film to form a filter body having a plurality of sloping walls formed by adjacent fold lines and apexes along the fold lines; extending the relatively thin first adhesive line along the apexes on at least one side of the filter body and applying a relatively thick second adhesive line to both sides of the filter media to form cross members extending between adjacent walls; and curing the adhesive to form a cured adhesive cross member.

[0013] In yet another non-limiting embodiment, the method of making an air filter further includes placing the filter body within a frame. In yet another non-limiting embodiment of the present invention, a relatively thin first line of adhesive is applied only to the surface of the filtration media that forms the exterior surface of the top portion.

[0014] According to another non-limiting embodiment of the present invention, a second relatively thick adhesive line is applied along the entire length of the filtration media. In yet another non-limiting embodiment of the present invention, a relatively thick first line of adhesive is applied to one side of the filtration media and a relatively thick second line of adhesive is applied to the other side of the filtration media, so that during the folding process, both sides of the filtration media have the relatively thick second line of adhesive applied to form the cross member.

[0015] In yet another non-limiting embodiment of the present invention, a first relatively thick line of adhesive and a second relatively thick line of adhesive are applied in the same application path on opposite sides of the filtration media. In yet another non-limiting embodiment of the method of the present invention, a relatively thick first adhesive line is applied to the filtration medium in a dotted line pattern, which, during the folding process, forms multiple cross-piece strips along the cross-piece axis between adjacent walls of the air filter body.

[0016] In another non-limiting embodiment of the present invention, the plurality of cross-member pieces form an arcuate cross-member. In yet another non-limiting embodiment of the present invention, the arcuate cross member protrudes upstream from the filter body.

[0017] Unless otherwise specified herein, the above features and elements can be combined in various configurations and in an unlimited number of ways. The above features, elements, and their functions will become more apparent from the following description and the accompanying drawings. It should be understood that the following description and drawings are for illustrative purposes only and are not intended to be limiting. [Brief explanation of the drawings]

[0018] Non-limiting embodiments of the present invention will now be described in detail with reference to the accompanying drawings. [Figure 1A] Cross section of a conventional air filter showing deformation challenges [Figure 1B] Cross-sectional view of a conventional air filter deformed by air flow pressure during use [Figure 1C] Cross-sectional view of a conventional air filter deformed by air flow pressure [Figure 1D] Cross-sectional view of a conventional air filter deforming in the opposite direction due to airflow pressure [Figure 2] 1 is a cross-sectional view of a conventional air filter with a reinforcing piece. [Figure 3] 3 is a perspective view of the conventional air filter shown in FIG. 2 with a reinforcing piece. [Figure 4] 1 is a perspective view of an air filter of the present invention with a reinforcing cross member; [Figure 5] 1 is a cross-sectional view of an air filter according to the present invention with a cross member. [Figure 6] A cross-sectional view of the air filter of the present invention shown in FIG. [Figure 7] FIG. 10 is a cross-sectional view of another embodiment with arcuate reinforcing cross members. [Figure 8A] Perspective view of the thin film used in the manufacturing method of the air filter of the present invention [Figure 8B] Perspective view showing the coating path for applying the adhesive to the thin film of FIG. 8A [Figure 8C] Cross-sectional view taken along line 8C-8C of FIG. 8B [Figure 8D] Cross-sectional view taken along line 8D-8D of FIG. 8B

Mode for Carrying Out the Invention

[0019] The present invention relates to a reinforced air filter and a manufacturing method thereof. The air filter of the present invention is formed by a cured adhesive applied in the manufacturing process and includes a cross member that enhances the mechanical resistance of the air filter against deformation during use.

[0020] FIGS. 1A to 1D schematically show a cross section of a conventional air filter 1. The air filter 1 schematically shown in FIG. 1A includes a filtering medium ② that forms adjacent inclined walls connected by a top (peak) or a fold (pleat) that is folded in a zigzag shape (a cross-sectional structure that bends in a Z shape) within a frame body 3. The airflow during use passing through the air filter 1 in the direction of arrow A tends to cause bending deformation to the air filter 1 along the fold line of the filtering medium ②. In one form of the deformation of the air filter shown in FIG. 1B, the central portion of the air filter 1 is curved and deformed by the airflow. In FIG. 1C, which is an enlarged view of a part of FIG. 1B, due to the airflow A, the central portion of the air filter 1 is deformed, and a difference in interval occurs between the upstream side folds and the downstream side folds. In the central portion of the illustrated air filter 1, the interval (a) between the upstream side folds is narrower than the interval (b) between the downstream side folds, and a < b. This causes an increase in pressure loss and a difficulty in further deformation of the air filter 1.

[0021] Also, in the peripheral portion of FIG. 1D adjacent to the central portion of the air filter 1 shown in FIG. 1C, the air filter 1 is deformed in the opposite direction to the central portion. Therefore, in the peripheral portion of the air filter 1, the interval (a) between the upstream side folds is wider than the interval (b) between the downstream side folds, i.e., a > b, which causes the characteristics of the continuously used air filter 1 to become unstable, and this is also undesirable. Due to the deformation shown in FIGS. 1A to 1D, there is a risk that the air filter 1 will eventually be damaged.

[0022] A conventional approach to addressing the above-described deformation of the air filter 1 is to provide a structure for attaching a reinforcing piece to one of the pleats of the air filter 1. In Figures 2 and 3, which show the air filter 1 within a frame 3, the reinforcing piece 5 shown in Figure 2 is positioned at position 4 shown in Figure 3, and the frame 3 is fixed to both ends of the reinforcing piece 5. Deformation of the air filter 1 at position 4 is prevented by the reinforcing piece 5. However, for the same reasons as described above for Figures 1A to 1D, the problem of deformation of the air filter 1 remains in the spaces between the reinforcing piece 5 and the multiple side walls parallel to the reinforcing piece 5.

[0023] Other features of the air filter shown in Figures 2 and 3 are also included in the following embodiments of the present invention. For example, the thickened portion (embossed portion) 6 formed on the filtration medium 2 shown in Figures 2 and 3 is useful for stabilizing the structure of the air filter 1. Also, the side edges 7 shown in Figures 2 and 3, which are located along the thickened portion or top of the filter body, function to maintain the desired shape of the filter body.

[0024] Figures 4 and 5 show the enhanced air filter 10 of the present invention. The filter medium 12 in Figure 4, which shows a perspective view of the air filter 10 of the present invention, is formed by a plurality of inclined walls 18 connected at the top 20 of the filter medium 12. The plurality of inclined walls 18 form a filter body (filter pack) attached to the frame 3 shown in Figure 3, constituting the air filter 10. Figure 4 shows a series of thickened portions (embossed portions) 14 formed along the first-fold intersection axis 19, together with the adhesive 15 that joins adjacent inclined walls 18. Further, the reinforcing cross member 24 formed along another fold intersection axis 21 is formed by an adhesive applied to both sides of the filter medium 12 or the inclined walls 18, and the cross member piece 26 is formed between adjacent inclined walls 18. Opposing the opening or closing movement of the inclined walls 18 due to the airflow flowing through the filter medium 12, the inclined walls 18 are supported and reinforced by the thickened portions 14, which helps prevent the problems of a > b or a < b with respect to Figures 1A to 1D. In the perspective view of Figure 4, the directly visible cross member piece 26 of the cross member 24 between the inclined walls 18 opening upward is shown by a solid line, and the non-directly visible cross member piece 26 between the inclined walls 18 opening downward is shown by a dashed line. The rigid cross member (solid cross member, solid beam) 24 having the cross member piece 26 between adjacent pairs of inclined walls 18 can prevent deformation of the air filter 10 that is significantly strengthened against bending deformation along the fold intersection axis 21.

[0025] In the present invention, the cross members 24 are formed by beads of adhesive on both sides (raised portions of adhesive joints, adhesive beads) that are applied and cured during manufacturing. The cross members 24, which are arranged generally transverse to the fold lines of the filter body (filtration medium) 12, are formed in the air filter 10 along one or more fold line intersecting axes 21, generally transverse to the conventional reinforcing pieces 5. In the air filter 10 of the present invention, adhesive is applied to both sides of the filtration medium 12 to form one or more relatively thick cross members 24. This forms a substantially rigid structure on both sides of the folded filtration medium 12 (upstream and downstream sides of airflow A in FIG. 1A), helping to prevent the bending problem described with reference to FIGS. 1A to 1D. In the present invention, as described below, the adhesive cross members are formed by applying relatively thick linear or beaded adhesive at desired locations before forming the filtration medium 12 into a zigzag shape. This allows for the formation of thick linear or beaded adhesive, strongly reinforced cross members 24 when the filtration medium 12 is folded.

[0026] FIG. 5 is a partial cross-sectional view of the air filter 10 of FIG. 4 taken along a cross member 24. The filtration media 12 having the thickened portion 14 shown in FIG. 4 is folded along fold lines 16 to form adjacent sloping walls 18 connected at alternating inverted peaks 20. FIG. 5 shows adhesive 22 surrounding the filtration media 12 on both the front and back sides. When the adhesive 22 hardens, a rigid cross member 24 is formed that is highly resistant to bending deformation as shown in FIGS. 1A-1D. The cross member 24 is formed by multiple cross member pieces 26 arranged along the cross member axis or cross-fold axis 21 (FIG. 4). The cross member pieces 26 arranged between a pair of sloping walls 18 support the adjacent sloping walls 18 and prevent bending deformation of the air filter 10.

[0027] When applying adhesive 22 to form the desired cross member 24, a substantially uniform or continuous adhesive 22 is applied to form the air filter 10 having the cross member 24 shown in FIG. 6. The substantially rigid cross member 24 of the embodiment shown in FIG. 6 forms cross member pieces 26 between the angled walls 18 to reinforce the space between the upstream and downstream apexes 20, extending along the cross-fold direction or cross-fold axis between the opposing walls 44 of the frame 3 of the air filter 10. Alternatively, as shown in FIG. 7, the cross member 24 can be formed by applying adhesive 22 separately or partially, and further applying adhesive 22 to both the front and back surfaces of the filtration media 12, although the cross member 24 need not surround the entire folded filter body 12. FIG. 7 shows an example of multiple cross member pieces 26 forming an arched cross member 28 that protrudes toward the upstream airflow. The arched cross member 28 enhances the air filter 10's resistance to bending deformation. Although not completely spanning the space between the oppositely projecting peaks 20, the arcuate cross members 28 in this example form a continuous cross member piece 26 extending between the walls 44 of the frame 3.

[0028] The air filter 10 of the present invention shown in FIG. 4 may have, for example, a single cross member 24 formed in the center of the air filter 10. Alternatively, multiple reinforcing cross members 24 may be arranged approximately parallel to one another. It is not necessary for each of the multiple reinforcing cross members 24 to be formed with the same thickness or the same amount of adhesive. For example, a small reinforcing cross member 24 may be added to one or the other of the multiple parallel side walls of the frame 3, in a position where the bending deformation force is small. Furthermore, the multiple cross members 24 do not necessarily need to be arranged parallel to one another, but may be arranged at slightly different angles from one another. Furthermore, the fold cross axis along which the cross members 24 are arranged does not necessarily need to be perpendicular to the fold line axis of the air filter 10. For example, the cross members 24 may be arranged at an angle from one side of the air filter 10 to the other.

[0029] The reinforcing cross members 24 disclosed herein can be formed or positioned along the filtration media in a variety of ways. A particularly advantageous method of forming the cross members is to apply adhesive during embossing of the filter body 12 after folding or pleating the filtration media 12, and then fold the filtration media 12. A small amount of adhesive can be used in the manufacture of the cross members to secure adjacent peaks 20 of the pleats, as is conventional. Figures 8A-8D illustrate a simplified inventive method of making a reinforced air filter.

[0030] FIG. 8A shows a substantially flat filter media film 30. For example, the filter media film 30 is typically transported by rollers through a manufacturing process that embosses the filter media 12, applies adhesive, and folds the filter media 12 into a zigzag configuration as shown. FIG. 8B shows an example in which the filter media film 30 is coated with relatively thin adhesive threads 32 that bond the peaks 20 of the filter media film 30 together and beads of adhesive 34 that bond the thickened (embossed) portions 6 together. For example, if an insufficient amount of adhesive is applied to the filter media film 30 during manufacturing to bond adjacent peaks 20 together, the bonded peaks 20 may separate. Alternatively, applying sufficient beads of adhesive 34 to both sides of the filter media film 30, as indicated by the upward and downward arrows 36 and 38, can advantageously form the reinforcing cross members 24 when the filter body 12 is folded into a predetermined shape. Adhesive 32 and 34 are applied along the same application path on both the front and back sides of the filter media membrane 30, and when the filter body 12 is folded, the adhesive on both sides aligns to form the desired reinforcing cross member 24.

[0031] The filtration medium (filter body) 12 removed from the adhesive application process can be folded into the desired finished shape shown in Figures 4 and 5-7. During the folding process, the thread-like adhesive 32 on both side edges contact and bond together at the thickened portions along the fold intersection line 19 (Figure 4), and the beads of adhesive 34 on both the front and back surfaces contact and bond together along the fold intersection line 21, forming the cross members 24. Figure 8C shows a cross-section of the folded filter body 12 taken along line 8C-8C in Figure 8B. The folded filter medium thin film 30 in Figure 8C forms an inclined wall 18 completely surrounded by the relatively thick adhesive 34 on both sides. As a result, the adhesive 34 on both the front and back surfaces of the filter medium thin film 30 forms a strong cross member 24, which supports the adjacent inclined wall 18 against bending deformation and prevents deformation of the air filter 10.

[0032] FIG. 8D shows a cross-sectional view of the filter body 12 taken along line 8D-8D in FIG. 8B, illustrating an example in which a relatively thin adhesive 32 is applied in a dotted line to form a hardened side edge 40 between adjacent thickened portions 42 of the angled wall 18.

[0033] In the illustrated embodiment of the present invention, it is preferred to apply one or more adhesive cross-member pieces 26 along the thickened portions 14 between the inclined walls 18 of the filter media body 12, thereby forming the cross-member pieces 26 along the thickened portions 14. Applying the adhesive to form the cross-member 24 along the thickened portions 14 has the advantage of forming relatively parallel thickened surfaces even with inclined cross-member walls, thereby forming glued cross-members 24 of substantially uniform thickness. However, it may be possible to position the cross-member 24 in an appropriate position without following the thickened portions 14. It is also desirable to provide reinforcing cross-member pieces 26 between the inclined walls 18 to support the inclined walls 18 on both the front and back sides. The cross-member pieces 26 shown in Figure 4 can completely embed the reinforcing portions within the cross-member 24 without following the reinforcing portions. Figure 5 also shows a cross-member 24 formed along the reinforcing portions 14.

[0034] The method for manufacturing an air filter according to the present invention includes a step of applying adhesive to both the front and back surfaces of the filtration medium, whether in the form of lines, beads, threads, fragments or portions thereof, and any known application method for applying adhesive to the base substrate of a movable filtration medium can be used.

[0035] As previously discussed, the application of one or more wide adhesive beads to provide adhesive bead reinforcement in the finished product can provide an air filter with the desired additional stiffness against bending. Also, thicker, wider adhesive can be applied near the center of the air filter and thinner adhesive can be applied near the generally parallel frame sidewalls. The resulting air filter with the single or multiple reinforcing cross members disclosed herein exhibits significant resistance to bending, as illustrated in Figures 1A-1D.

[0036] The filtration media for use in the present invention can be suitably manufactured from glass fibers, cellulose fibers, synthetic fibers (e.g., polypropylene, polyester, etc.), or combinations thereof. Adhesives that can be advantageously used include copolymer adhesives such as ethylene vinyl acetate (EVA), polyester hot melt, or polyurethane. Other suitable adhesives include amorphous polyalphaolefins (APAO), polyamides (PA), reactive polyurethanes (PUR), or other EVA-based adhesives.

[0037] The foregoing description is merely illustrative of the gist of the invention disclosed herein. While various non-limiting embodiments are disclosed, those skilled in the art will appreciate that various modifications and variations based on the above disclosure are within the scope of the claims. Therefore, it should be understood that the invention of the claims can be practiced in ways other than those described in the specification. In short, the scope of the claims is not limited to the details of the specific embodiments disclosed herein, but the full and reasonable scope of the invention is defined by each claim.

Claims

1. an air filter body having a filtration medium folded along a plurality of fold lines and a plurality of adjacent sloped walls formed on the filtration medium connecting and dividing the tops at the fold lines; and a cross member fixed to both inclined walls of the filtering medium and positioned laterally of the fold line.

2. 2. The air filter of claim 1, wherein the cross members are formed from a cured adhesive material.

3. 2. The air filter of claim 1, wherein the cross member is a rigid cross member extending the entire depth of the filtration media from the upstream apex to the downstream apex.

4. 2. The air filter of claim 1, wherein the cross member comprises a plurality of cross member pieces disposed along a cross member axis between adjacent angled walls of the filtration media.

5. 5. The air filter of claim 4, wherein the plurality of cross-member pieces form an arcuate cross-member.

6. 6. The air filter of claim 5, wherein the arcuate cross member projects upstream of the air filter.

7. 10. The air filter of claim 1, further comprising a hardened adhesive strand disposed along the top of the filtration media.

8. 8. The air filter of claim 7, wherein the cured adhesive strands are disposed on both sides of the cross member.

9. 2. The air filter of claim 1, wherein a plurality of cross pieces are disposed laterally on top of the filtration media.

10. 10. The air filter of claim 1, comprising a filter media frame having a plurality of side walls and a filter media mounted within the filter media frame.

11. 2. The air filter of claim 1, wherein the cross members of the filter media extending continuously between each pair of adjacent inclined walls reinforce the filter media against bending deformation due to airflow pressure on the filter media.

12. applying adhesive to a flat thin film on both sides of the filtration media along a first relatively thin line of adhesive along the top of at least one side of the filtration media and at least one second relatively thick line of adhesive; folding a flat film of filtration media having a plurality of sloping walls formed by adjacent fold lines and a crest along the fold lines; and curing the adhesive of the first adhesive line and the second adhesive line of the filtration media to form a cured adhesive cross member extending between adjacent angled walls.

13. 13. The method of claim 12, further comprising the step of placing a filter media within a frame of the air filter.

14. 13. The method of claim 12, including the step of applying a relatively thin first line of adhesive only to the surface of the filtration media forming the exterior surface of the top portion.

15. 13. The method of claim 12, further comprising the step of applying a second relatively thick adhesive line along the entire length of the filtration media.

16. applying adhesive to one side of the filtration media along a relatively thick first adhesive line; applying adhesive to the other side of the filtration media along a second relatively thick line of adhesive; 13. The method of claim 12, further comprising the step of folding the filtration media and joining the cross members formed by a second relatively thick adhesive line applied to both sides of the filtration media.

17. 17. The method of claim 16, further comprising applying adhesive along the same application path to a first relatively thick adhesive line and a second relatively thick adhesive line on opposing surfaces of the filtration media.

18. applying adhesive in a dotted line along a relatively thick first adhesive line of the filtration media; and folding the filtration media to form cross members along the cross member axis between adjacent angled walls of the filtration media.

19. 20. The method of claim 18, further comprising forming a plurality of crosspieces into an arcuate crosspiece.

20. 20. A method for making an air filter as defined in claim 19, including the step of forming a projecting arcuate cross member on the upstream side of the filter body.

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