Flat filter element having a defined bending region

Abstract

The invention relates to a filter element having a pleated filter medium body. The filter medium body is obtained by zigzag folding of a flat filter medium. A circumferential seal for sealing the filter medium body with respect to a filter housing is located on a first side of the filter medium body. The filter medium body is additionally reinforced in some regions on a second side. Glue beads are applied for reinforcement purposes to a filter medium surface facing the second side. Within folds which are open towards the second side, said glue beads stick the respective flanks of the folds to one another. The glue beads serving for reinforcement purposes are interrupted between the stiffened regions. The folds which are open towards the second side therefore remain flexible in this region. In the flexible intermediate region, the reinforced regions of the filter medium body can be angled with respect to one another towards the first side. This can facilitate the installation of the filter element.

Description

[0001] FLAT FILTER ELEMENT WITH DEFINED BENDING AREA

[0002] This patent application claims priority over German patent application No. DE102024119418.9, which was filed with the German Patent and Trademark Office on 09.07.2024, the contents of which are hereby incorporated by reference.

[0003] Technical field

[0004] The invention relates to a filter element with a filter medium body with a pleated filter medium, wherein flanks of pleats extend between first pleat edges, which lie on a first side of the filter medium body, and second pleat edges, which lie on a second side of the filter medium body, wherein the pleat edges follow one another in a longitudinal direction and extend in a transverse direction, wherein first pleats are open towards the first side and second pleats are open towards the second side, and wherein a circumferential seal is arranged on the filter medium body at the first side.

[0005] State of the art

[0006] Such filter elements are well known in the prior art.

[0007] Such filter elements are used, for example, to filter intake air for combustion engines. However, in vehicle engine compartments, the available installation space for the filter is often severely limited. In particular, it may happen that a filter housing cannot be fully opened to accommodate the filter element, but rather that two housing parts can only be tilted relative to each other at a certain angle. The filter element then cannot be inserted perpendicular to its plane of extension, but must essentially be pushed between the housing parts along its plane of extension. This requires a certain degree of rigidity in the filter element. To insert it, the filter element often has to be angled relative to the housing part into which the filter medium body engages.If the filter element is rigid and convex on its leading edge (in the insertion direction), a portion of the filter medium body protruding beyond the line connecting the longitudinal sides will sink into the housing. This portion of the filter medium body can then collide with ribs or other components in the housing or with a sealing contour on the filter housing, potentially causing damage. Restrictions on access to the filter housing due to other components in the vicinity can also make inserting a rigid filter element difficult or impossible. US 2011 / 023427A1 describes a filter element with two separate filter medium bodies. Both filter medium bodies are held in a common filter holder, which serves to seal against a housing. The sealing filter holder also extends between the two filter medium bodies.A dividing line between the filter media bodies runs parallel to the folded edges of the two filter media bodies. A rib of the housing engages between the two filter media bodies to seal them against each other by contacting the filter holder.

[0008] It is an object of the invention to provide a flat filter element that can be mounted in confined spaces and that can be inserted into a filter housing in particular.

[0009] Disclosure of the invention

[0010] This problem is solved by a filter element according to claim 1 and a filter device according to claim 15. Advantageous embodiments are specified in the dependent claims and the description.

[0011] According to the invention, a filter element is provided with a filter medium body made of pleated filter medium. The filter element can be referred to as a flat filter element. The filter medium body is obtained from a single, continuous piece of filter medium. The filter medium can be filter paper with cellulose fibers and / or plastic fibers or a filter fleece.

[0012] The filter element is advantageously designed for filtering gas, particularly air; it can therefore be a gas filter element. The filter element can be used as an engine air filter for filtering combustion air for an internal combustion engine, especially in a motor vehicle. Use as a cathode air filter for a fuel cell, particularly in a motor vehicle, is also possible. Other applications are also conceivable.

[0013] The flanks of folds in the filter medium body extend between first fold edges, located on a first side of the filter medium body, and second fold edges, located on a second side of the filter medium body. When installed, the first fold edges typically lie in a first plane. The second fold edges may lie in a second plane. The fold edges follow each other longitudinally. The fold edges extend in a transverse direction. Generally, all fold edges extend parallel to each other. The longitudinal and transverse directions are typically orthogonal to each other.

[0014] First folds are open towards the first side. Second folds are open towards the second side. First and second folds alternate lengthwise. The first fold lines separate adjacent first folds on the first side. The second fold lines separate adjacent second folds on the second side.

[0015] The two flanks that define each (first or second) fold are also referred to as the flanks of that fold. Apart from the first and last flanks in the longitudinal direction, each flank is associated with both a first and a second fold.

[0016] A circumferential seal is arranged on the first side of the filter medium body. In other words, the seal completely encloses the filter medium body on this first side. This first side can be the outflow side (clean side) of the filter element. The seal is typically permanently bonded to the filter medium body. For example, the seal can be foamed or cast onto the filter medium body. A seal permanently bonded to the filter medium body cannot be removed from it without damage. The outer end sections of the first fold edges, in the transverse direction, can be embedded in the seal. Similarly, the free ends of the outermost longitudinal flanks of the two outermost first folds can be embedded in the seal.

[0017] According to the invention, in at least two stiffening regions of the filter medium body extending along the longitudinal direction, the flanks within the second folds are bonded together by at least one bead of adhesive. In other words, the at least one bead of adhesive fixes the flanks of the second folds to one another in the two stiffening regions, with the bonded flanks facing each other with respect to the respective second fold. The second folds of the stiffening regions can therefore not be compressed or stretched in the longitudinal direction. The stiffening regions typically extend over at least 30 second folds, and in particular over at least 50 second folds.

[0018] On the first side, the seal can hinder or prevent compression or expansion of the first folds. In the stiffening regions, the filter element is therefore stiff or essentially rigid. The stiffening regions are spaced apart longitudinally. A bending region separates the adjacent stiffening regions. The bending region includes at least one second fold.

[0019] Furthermore, according to the invention, in at least one bending region arranged between the stiffening regions, the flanks of at least one second fold are movable relative to each other in the longitudinal direction. In the bending region, the second folds can thus be compressed or stretched in the longitudinal direction.

[0020] The seal also prevents compression or stretching of the first folds in the bending area. However, the seal allows the filter element to be bent around an (imaginary) bending axis running transversely in the bending area. Two adjacent stiffening areas can thus be angled relative to each other by bending the filter medium body and the seal in the intervening bending area around the transverse bending axis. This simplifies the insertion of the filter element in confined installation spaces. In particular, the stiffening area of ​​the filter element at the front (in the insertion direction) can lie flat against a housing part, while the stiffening area at the rear (in the insertion direction) is raised from the housing part. This can prevent collisions of the second folded edges with ribs or other internal components in the housing part or with a seal seat of the housing part.

[0021] The longitudinal stiffness provided by the adhesive beads and the seal in the stiffening areas allows the filter element to be fully advanced into the filter housing with sufficient force. At the same time, the stiffness of the seal is sufficient to ensure force transmission within the locally limited bending range.

[0022] Once the filter element is fully inserted into the housing, the rear stiffening section (in the insertion direction) can be pivoted back into the plane of the first stiffening section. The filter housing can then be closed.

[0023] The ability to bend the filter element in the bending area can also be used if components adjacent to the filter housing prevent straight-line access to an insertion opening for the filter element. The stiffening areas can encompass longitudinally outer end regions of the filter medium body. Up to five longitudinally outermost folds on one or both end regions of the filter medium body can be free of a glue bead.

[0024] The stiffening adhesive beads are typically applied to the second side of the filter medium after it has been folded, in the area of ​​the second fold edges. Generally, the adhesive beads are applied by moving nozzles for applying the adhesive and the filter medium body longitudinally relative to each other. An adhesive bead is understood to be, in particular, a transversely bounded bead of adhesive of any type suitable for the filter medium. After the filter medium has been folded, the adhesive beads bridge the gap between the sides of the second folds.

[0025] Advantageously, in at least one bending area, the flanks within the second folds are not glued together. The at least one bead of glue can be interrupted in the bending area located between the stiffening areas. In particular, the second folds in the bending area can be free of glue. This simplifies manufacturing. When applying the glue beads after folding the filter medium, the bending areas are omitted. For this purpose, nozzles for glue application can be switched off. As soon as a subsequent stiffening area is reached, the glue application is restarted.

[0026] Alternatively, an elastic adhesive could be used in the bending area.

[0027] The side surfaces of the filter medium body can extend parallel to each other and parallel to the longitudinal direction. This can simplify the insertion of the filter element into the filter housing, as the seal can rest on and slide onto an edge or sealing seat of the filter housing regardless of the insertion depth.

[0028] In an end region of the filter medium body, the length of the fold edges, measured along the respective fold edge, can increase longitudinally from a terminal fold edge. The length of the terminal fold edge can be at least one-fifth and at most four-fifths, in particular at least one-quarter and / or at most three-quarters, of the maximum length of the fold edges. This can improve the utilization of the available installation space and increase the filter performance. In the remaining longitudinal region of the filter element, the length of the fold edges can be constant. The end region with increasing fold edge length and one of the stiffening regions can overlap each other, at least partially, in the longitudinal direction. The length of the fold edges can increase continuously across several fold edges. In this case, a chamfer is formed on the filter medium body.Alternatively, the length of the fold edges can increase abruptly, with a majority of fold edges having the same length as the terminal fold edge. This creates a rectangular cutout in the filter medium body.

[0029] In this design, the filter medium body has a corner between its side surfaces, particularly the parallel ones, at an inner end of the short terminal fold. This corner projects beyond an imaginary line connecting the endpoints of the (parallel) side surfaces. If the end region were angled relative to a sealing seat of the filter housing, this corner would sink into the housing section and could collide with ribs, other components, or the sealing seat. This could cause damage and complicate the installation of the filter element. Furthermore, the seal could malfunction if it does not reach its intended position at the sealing seat; this could result in unfiltered raw air bypassing to the clean side. The bending area allows the stiffened end region to lie flat on the sealing seat of the housing section, while an adjacent stiffening area is angled.This allows the filter element to be installed without damage, even in confined workspaces, by simply sliding it in.

[0030] At least one of the stiffening areas can comprise at least one quarter, and in particular at least one third, of the total number of successive second folds in the longitudinal direction. Specifically, the two stiffening areas can each comprise at least one quarter, and in particular at least one third, of the total number of successive second folds in the longitudinal direction. If the number of successive folds varies in the transverse direction, the total number refers to the largest number of successive folds in the longitudinal direction.

[0031] The distance of the bending section from a terminal fold can be between a quarter and half of the total number of successive second folds along its length. With a constant fold spacing, the bending section can therefore be located at approximately one-third of the total length of the filter medium body.

[0032] These length ranges have proven advantageous for inserting the filter element. The bending area can include at least two, and in particular at least three, secondary folds. This minimum number of secondary folds in the bending area prevents the seal from experiencing a sharp kink when the filter element is bent, which could damage the seal. Furthermore, it reduces the risk of the seal detaching from the filter medium body during bending.

[0033] The bending area can comprise a maximum of ten, and in particular a maximum of six, second folds. This prevents the longitudinal stiffness of the filter element from decreasing excessively. In particular, buckling of the seal in the bending area when inserting the filter element can be avoided if the length of the bending area is limited.

[0034] It has proven particularly advantageous if the bending area includes three to five second folds.

[0035] The glue beads in adjacent stiffening areas can lie in a straight line with each other.

[0036] Alternatively, the glue beads in adjacent stiffening areas can be offset from each other transversely to the longitudinal direction. If nozzles are used to apply the glue beads, they are generally switched off in the bending area. By using different application nozzles, offset in the transverse direction, for glue beads in adjacent stiffening areas, the length of the bending area can be kept sufficiently short even at high production speeds, or the production speed can be increased for a given bending area length, although such a nozzle cannot be switched back on arbitrarily quickly after being switched off.

[0037] Exactly two stiffening areas and exactly one bending area located between the two stiffening areas can be provided. This simplifies the manufacturing of the filter element. At the same time, the filter element is largely stiffened along its entire length, making it easy to handle.

[0038] Alternatively, at least two bending zones and at least three stiffening zones can be provided on the filter medium body. This allows for particularly large deformations of the filter element for installation in especially difficult-to-access spaces. In particular, exactly two bending zones and exactly three stiffening zones can be provided. The hardness of the seal can be at least 20 Shore A, in particular at least 21 Shore A. This ensures that the seal is sufficiently hard to provide the filter element with adequate longitudinal stiffness in the bending zone.

[0039] The hardness of the seal can be a maximum of 32 Shore A, and in particular a maximum of 30 Shore A. This ensures that the seal is sufficiently flexible to allow the filter element to bend and to provide a reliable seal.

[0040] A seal hardness of 22+ / -1 Shore A, in particular 22 Shore A, has proven to be particularly advantageous.

[0041] The hardness can be measured according to ISO 48-4.

[0042] A design of the filter element with three to five unglued folds in the bending area and a seal with a hardness of 22+ / -1 Shore A, in particular 22 Shore A, has proven to be particularly advantageous.

[0043] The seal can be made of polyurethane foam. Polyurethane foam can be efficiently molded to the filter medium body and exhibits good sealing properties. Furthermore, polyurethane foam is available in suitable hardness.

[0044] The edges within the first folds can be bonded together by an additional bead of glue. This further bead of glue generally runs continuously along the length of all the first folds of the filter medium body, close to the outer edges of the folds in the transverse direction. In this way, a seal of the first folds can be achieved in the transverse direction. The additional beads of glue for sealing the first folds are typically applied before folding the filter medium to the surface that, after folding, will be associated with the first folds and faces the first side.

[0045] Alternatively, the first folds can be sealed in the transverse direction by a sideband, wherein the sideband for the second folds of the at least one bending region has a slot open at the edge and extending from the second side. The slots extending from the edge of the sideband on the second side of the filter medium body allow or support the deformation of the sideband in the bending region without impairing its sealing effect at the first folds. It is understood that the sideband has sufficient flexibility to allow certain deformations adjacent to the slots without tearing.

[0046] The invention further relates to a filter device comprising a filter element as described above and a filter housing with two housing parts. In particular, the maximum width of an insertion opening for the filter element that can be provided between the housing parts can be a maximum of one-quarter of the total length of the filter medium body and / or a maximum of four times the thickness of the filter medium body. The advantages of the inventive design of the filter element are particularly evident when the insertion opening is so narrow, especially due to external boundary conditions.

[0047] The thickness of the filter element corresponds to the distance between the first and second folded edges, measured perpendicular to the longitudinal and transverse directions. If the thickness of the filter medium body is not constant, the greatest thickness is used as a reference point.

[0048] Brief description of the drawings

[0049] Further features and advantages of the invention will become apparent from the following detailed description of exemplary embodiments of the invention, from the claims, and from the figures in the drawing, which illustrate details of the invention. The aforementioned and further described features can be implemented individually or in any suitable combination in variants of the invention. The features shown in the drawing are presented in such a way as to clearly demonstrate the special features of the invention.

[0050] The drawing shows:

[0051] Fig. 1 shows a filter element according to the invention during assembly into a filter housing, of which only a housing lower part is shown, in a schematic perspective view;

[0052] Fig. 2 is a schematic top view of the arrangement of Figure 1;

[0053] Fig. 3 shows a schematic longitudinal section through the arrangement of Figure 1;

[0054] Fig. 4 shows a schematic diagram of a filter device according to the invention with a filter element according to the invention;

[0055] Fig. 5 shows the arrangement of Figure 1 with the filter element fully advanced, but whose rear area is not yet lowered into the lower part of the housing, in a schematic perspective view; Fig. 6 shows a schematic sketch of the longitudinal section of a filter element according to the invention with a folded filter medium, the upwardly open folds of which are sealed by a continuous bead of glue and the downwardly open folds of which are stiffened in two stiffening areas by an interrupted bead of glue;

[0056] Fig. 7 shows a top view of a first side of a planar filter medium for a filter element according to the invention before folding, with continuous glue beads for sealing first folds;

[0057] Fig. 8 shows a top view of a second side of a planar filter medium for a filter element according to the invention, in the unfolded state with interrupted glue beads for area-wise stiffening of second folds;

[0058] Fig. 9 shows a schematic diagram of another filter element according to the invention with a folded filter medium, the upwardly open folds of which are sealed by a side band and the downwardly open folds of which are stiffened in two stiffening areas by an interrupted bead of glue.

[0059] Embodiments of the invention

[0060] Figures 1 to 3 show a filter element 10 being assembled into a filter housing with two housing parts. For clarity, only the second housing part 12, here a lower housing part, is shown. Figure 4 shows that, due to components indicated by dashed lines in the installation space, the first housing part 13, here the upper housing part, cannot be removed from the second housing part 12 in a filter device 15 with the filter element 10, but can only be positioned to a limited extent. The filter element 10 must therefore be inserted between the housing parts 12 and 13 and cannot be inserted into the housing part 12 from above.

[0061] The filter element 10 comprises a filter medium body 14 made of pleated filter medium 16, for example, cellulose-containing filter paper, see Figures 1 to 3. A circumferential seal 20 is arranged on a first side 18 of the filter medium body 14, which here faces upwards. The seal 20 can be made of polyurethane foam with a hardness of 22 Shore A. The seal 20 can be foamed onto the filter medium body 14.

[0062] The filter medium body 14 can be permeated from a second side 22 to the first side 18. An air inlet 24 can be formed on the housing part 12. An air outlet 25 can be formed on the housing part 13, see Figure 4. The housing part 12 has a sealing seat 26 on its free edge. In the assembled state, the seal 20 rests against the sealing seat 26, sealing against it. During assembly, the seal 20 can slide along the sealing seat 26.

[0063] As can be seen particularly in Figure 2, two side surfaces 28, 30 of the filter medium body 14 run parallel to each other in a longitudinal direction 32. Folds of the filter medium body 14 follow one another in the longitudinal direction 32 and extend perpendicular to this in a transverse direction 34. In the longitudinal direction 32, the folds are evenly spaced from each other.

[0064] The filter element 10 is chamfered at a front end. The length 36 of a front fold, measured in the transverse direction 34, is almost half the maximum length 38 of the folds in the region of the parallel side surfaces 28, 30. Therefore, the filter element 10 has a corner 40 between the front ends of the parallel side surfaces 28, 30, which projects beyond an imaginary connecting line between the front ends 41a, 41b of the parallel side surfaces 28, 30.

[0065] To prevent this corner 40 from sinking into the housing part 12 during assembly, a front portion of the filter element 10 (in the insertion direction) is positioned flat against the housing part 12. A rear portion of the filter element 10 is raised to prevent collisions with the rear edge of the housing part 12. These two portions are stiffened by adhesive beads 42, 43 on the second side 22 facing away from the seal 20 (see Figure 3); they are therefore also referred to as stiffening areas 44, 46.

[0066] Between the two stiffening areas 44, 46, a bending area 48 is provided in which the glue beads 42, 43 are interrupted. In other words, there are no glue beads on the second side 22 in the bending area 48.

[0067] In the bending area 48, the seal 20 and the first folded edges on the first side 18 act as a kind of hinge, which allows the adjacent stiffening areas 44, 46 to be angled relative to each other.

[0068] The front stiffening section 44 extends over approximately one-third of the total length of the filter medium body 14. The rear stiffening section 46 extends over just under two-thirds of the total length of the filter medium body 14. The glue beads 42, 43 terminate here shortly before the foremost and rearmost folds in the longitudinal direction 32. When the filter element 10 is fully advanced so that the seal 20 also rests against the seal seat 26 at the front end of the filter element 10 (see Figure 5), the rear stiffening section 46 can be lowered into the housing part 12 so that the seal 20 comes into contact with the seal seat 26 all around (see Figure 4). The filter housing can then be closed.

[0069] The maximum width 50 of an insertion opening 52 between the housing parts 12, 13 can be less than four times the thickness 54 of the filter medium body 14 and less than one-quarter of the total length 56 of the filter medium body 14. It should be noted that the sketch in Figure 4 is not to scale.

[0070] Figure 6 shows a schematic longitudinal section with details of the filter element 10. On the first side 18, the filter medium body 14 has first folded edges 58. On the second side 22, the filter medium body 14 has second folded edges 60. The folded edges 58 and 60 run in the transverse direction 34 (perpendicular to the plane of the drawing) and alternate in the longitudinal direction 32. The seal 20 is arranged in the area of ​​the first folded edge 58.

[0071] Between the fold edges 58, 60, flanks 62 of folds extend. First folds 64 are open towards the first side 18. Second folds 66 are open towards the second side 22. Each fold 64, 66 is bounded in the longitudinal direction 32 by two adjacent flanks 62; these flanks 62 are also referred to as the flanks 62 of the respective fold 64, 66. Except for the outermost flanks, each flank 62 bounds both a first and a second fold 64, 66; the flanks 62 are thus generally assigned to two adjacent folds 64, 66.

[0072] In the stiffening regions 44, 46, the flanks 62 of the second folds 66 are bonded together by the glue beads 42, 43. The second folds 66 therefore cannot be compressed or stretched. The stiffening regions 44, 46 generally comprise significantly more second folds 66 than are schematically depicted in Figure 6 for clarity; typically, each stiffening region 44, 46 comprises at least 30 second folds 66.

[0073] In the bending region 48, the flanks 62 of the second folds 66 are not bonded together. Rather, the second folds in the bending region 48 are free of adhesive. The second folds 66 in the bending region 48 can therefore be compressed and, in particular, stretched, whereby the flanks 62 approach or move away from each other. The bending region 48 here comprises, by way of example, three second folds 66. Four or five second folds 66 could also form the bending region 48.

[0074] The first folds 64 are sealed in the transverse direction by further glue beads 68 extending in the longitudinal direction 32, which connect the flanks 62 of the first folds 64 to each other. The further glue beads 68 run laterally along the filter medium 16 on a first surface 18a facing the first side 18, see Figure 7.

[0075] Figure 8 shows possible arrangements for glue beads 42, 43, 70 for stiffening the second folds 66 in three stiffening areas 44, 46, 72 of a filter element 10 with two bending areas 48, 73. The glue beads 42, 43, 70 run on a second surface 22a of the filter medium 16 facing the second side 22. Although the glue beads 42, 43, 70 are generally applied from the second side 22 in the area of ​​the second fold edges 60 after the filter medium 16 has been folded, the filter medium 16 is shown here in its flat or unfolded state. The glue beads 42, 43, 70 are shown as solid lines to illustrate their extent - and especially interruptions in the bending areas 48, 73 - although in the second folds 66 they typically do not extend to the first fold edges 58, compare Figure 6.

[0076] In order to obtain a filter element 10 with two stiffening areas 44, 46 (as shown in Figures 1 to 6), the glue beads 70 could be omitted and the glue beads 42 could be extended to the right end of the filter medium 16 in Figure 8.

[0077] The glue beads 42, 43, 70 can be aligned with each other when viewed in the longitudinal direction 32. Figure 8 illustrates this by way of example for the glue beads 42, 43, 70 running along a long side edge 74. These glue beads 42, 43, 70 for stiffening and the further glue bead 68 for sealing the end face of the first folds 64 can be arranged overlapping each other, see also Figure 6; however, this is not necessary. After the filter medium 16 is folded, the long side edge 74 forms the long side surface 28 of the filter medium body 14.

[0078] Alternatively, the glue beads 42, 43, 70 can be offset from one another. Figure 8 illustrates this by way of example for the glue beads 42, 43, 70 running closer to a short side edge 76. After folding the filter medium 16, the short side edge 76 forms the short side surface 30 of the filter medium body 14. Figure 9 shows another filter element 10', which largely corresponds to the filter elements 10 described above and shown in particular in Figure 6. The differences are explained primarily below; for further details, please refer to the preceding description.

[0079] To seal the first folds 64 on the side surfaces 28, 30, a side band 78 is provided on each of the filter elements 10'. The side band 78 is bonded to the end edges (corresponding to the side edges 74, 76 in the unfolded state as shown in Figure 8) of the filter medium 16. On the first side 18 of the filter medium body 14, the side band 78 can be embedded in the seal 20. On the second side 22, the side band 78 can protrude slightly beyond the second folded edges 60.

[0080] In the bending area 48, the side band 78 has a slot 80 for each of the second folds 66. The slots 80 extend from the free edge of the side band 80 on the second side 22. The slots end here shortly before the first fold edge 58 within the second folds 66. The slots 80 ensure that the side band 78 does not impede the stretching of the second folds 66 in the bending area 48.

[0081] In summary, the invention relates to a filter element with a pleated filter medium body. The filter medium body is obtained by pleating a flat filter medium in a zigzag pattern. A circumferential seal is arranged on a first side of the filter medium body to seal it against a filter housing. On a second side, the filter medium body is additionally stiffened in certain areas. Adhesive beads are applied to the surface of the filter medium facing the second side for stiffening purposes. These adhesive beads bond the respective flanks of the folds open towards the second side. The adhesive beads serving as stiffeners are interrupted between the stiffened areas. The folds open towards the second side therefore remain flexible in this area. The stiffened areas of the filter medium body can be angled relative to each other towards the first side in the flexible intermediate area.This can facilitate the installation of the filter element. Reference list.

[0082] Filter element 10; 10' second housing part 12 first housing part 13 filter medium body 14

[0083] Filter device 15

[0084] Filter medium 16 first side 18 first surface 18a circumferential seal 20 second side 22 second surface 22a

[0085] Air intake 24

[0086] Air outlet 25

[0087] Seal seat 26

[0088] Side surfaces 28, 30

[0089] Longitudinal direction 32

[0090] transverse direction 34

[0091] Length 36 of a foremost fold, maximum length 38 of the folds, corner 40, front ends 41a, 41b, glue beads 42, 43, 70, stiffening areas 44, 46, 72, bending area 48, 73, maximum width 50

[0092] Insertion opening 52

[0093] Thickness 54

[0094] Total length 56, first fold edges 58, second fold edges 60

[0095] Flanks 62 first folds 64 second folds 66 further glue bead 68

[0096] Side edge 74, 76

[0097] Volume 78

[0098] Slot 80

Claims

Claims 1. Filter element (10; 10') with a filter medium body (14) made of pleated filter medium (16), wherein flanks (62) of pleats (64, 66) extend between first pleat edges (58) located on a first side of the filter medium body and second pleat edges (60) located on a second side (22) of the filter medium body (14), wherein the pleat edges (58, 60) follow one another in a longitudinal direction (32) and extend in a transverse direction (34), wherein first pleats (64) are open towards the first side (18) and second pleats (66) are open towards the second side (22), wherein a circumferential seal (20) is arranged on the filter medium body (14) at the first side (18), wherein stiffening regions (44, 46, 72) extending along the longitudinal direction (32) of the The flanks (62) of the filter medium body (14) within the second folds (66) are bonded together by at least one bead of glue (42, 43, 70),and wherein in at least one bending region (48, 73) arranged between the stiffening regions (44, 46, 72) the flanks (62) of at least one second fold (66) are movable relative to each other in the longitudinal direction (32).

2. Filter element (10; 10') according to claim 1, wherein in the at least one bending region (48, 73) the flanks (62) within the second folds (66) are not bonded together.

3. Filter element (10; 10') according to one of the preceding claims, wherein in an end region of the filter medium body (14) a length of the fold edges (58, 60) measured along the respective fold edge (58, 60) increases from a terminal fold edge in the longitudinal direction (32), in particular wherein a length (36) of the terminal fold edge is at least one fifth and / or at most four fifths of the maximum length (38) of the fold edges (58, 60).

4. Filter element (10; 10') according to one of the preceding claims, wherein at least one of the stiffening areas (44, 46, 72) comprises at least one quarter of the total number of successive second folds (66) in the longitudinal direction (32), in particular wherein the two stiffening areas (44, 46) each comprise at least one quarter of the total number of successive second folds (66) in the longitudinal direction (32).

5. Filter element (10; 10') according to one of the preceding claims, wherein the bending area (48, 73) comprises at least two, in particular at least three, second folds (66).

6. Filter element (10; 10') according to one of the preceding claims, wherein the bending area (48, 73) comprises a maximum of ten, in particular a maximum of six, second folds (66).

7. Filter element (10; 10') according to one of the preceding claims, wherein the glue beads (42, 43, 70) are offset from each other transversely to the longitudinal direction (32) in adjacent stiffening areas (44, 46, 72).

8. Filter element (10; 10') according to one of the preceding claims, wherein two bending areas (48, 73) and three stiffening areas (44, 46, 72) are provided.

9. Filter element (10; 10') according to one of the preceding claims, wherein the hardness of the seal (20) is at least 20 Shore A, in particular at least 21 Shore A.

10. Filter element (10; 10') according to one of the preceding claims, wherein the hardness of the seal (20) is at most 32 Shore A, in particular at most 30 Shore A.

11. Filter element (10; 10') according to one of the preceding claims, wherein the seal (20) consists of a polyurethane foam.

12. Filter element (10; 10') according to one of the preceding claims, wherein the filter medium (16) is a filter paper with cellulose and / or plastic fibers or a filter fleece.

13. Filter element (10) according to any one of claims 1 to 12, wherein the flanks (62) within the first folds (64) are bonded together by a further bead of adhesive (68).

14. Filter element (10') according to any one of claims 1 to 12, wherein the first folds (64) are sealed in the transverse direction (34) by a side band (78), the side band (78) having a slot (80) open at the edge and extending from the second side (22) for each of the second folds (66) of the at least one bending region (48).

15. Filter device (15) comprising a filter element (10; 10') according to one of the preceding claims and a filter housing with two housing parts (12, 13), in particular wherein a maximum width (50) of an insertion opening (52) for the filter element (10; 10') that can be released between the housing parts (12, 13) is at most one quarter of a total length (56) of the filter medium body (14) and / or at most four times a The thickness (54) of the filter medium body (14) is...

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