Filter element and filter device

Abstract

The present invention relates to a filter element (10), in particular an air filter element, having two filter bellows (1, 2), which allow a medium to flow through them in series. The filter bellows (1, 2) adjoin one another in an interface region (S) between an outflow surface (12) of a first filter bellows (1) and in inflow surface (21) of a second filter bellows (2). An all-around seal (3) is located in the interface region (S), which seal integrally connects the two filter bellows (1, 2) to one another. One of the filter bellows (1, 2) has a smaller extent in at least one direction transverse to the flow direction (D) than the other filter bellows (1, 2), wherein the filter bellows (1, 2) are arranged relative to one another in the at least one direction transverse to the flow direction (D) such that there is a free space (F) on the inflow surface (11, 21) or outflow surface (12, 22) of the larger filter bellows (1, 2) along at least one edge of the larger filter bellows (1, 2) in the interface region (S). The all-around seal (3) is integrally connected directly to the larger filter bellows (1, 2) in the region of the free space (F). A filter device (100) having a filter element (10) according to the invention is also disclosed.

Description

[0001] Filter element and filter device

[0002] Technical area

[0003] The present invention relates to a filter element, in particular an air filter element, for an air filter system, in particular for a cabin air filter system or an intake air filter system of a fuel cell. Furthermore, the invention relates to a filter device comprising such a filter element.

[0004] A filter element or filter insert is generally understood to be a replaceable unit that can be arranged in a filter housing. It comprises at least one filter medium body made of a filter medium, often in the form of a pleated filter bellows, and usually also a structure that carries or supports the filter medium, and usually a seal. The respective filter medium typically has a limited service life. Therefore, filter elements must be replaced regularly as a unit.

[0005] Today, the air flowing into a vehicle cabin is cleaned as completely as possible of contaminants. Possible contaminants include fine dust, pollen, soot, and aerosols. Filtering such contaminants is particularly important in applications where high concentrations of pesticides or liquid fertilizers occur in the ambient air when spraying these substances. Various filter media are available for this purpose. Particle filters, activated carbon filters, and HEPA filters, for example, are regularly used. These are combined in various layers and configurations to achieve the desired filtering effect for the interior air.

[0006] Since in practice combinations of various pollutants to be separated occur, the approach of multi-stage filter systems or elements has become established.

[0007] State of the art

[0008] EP 3 520 878 A1 discloses a filter module for filtering indoor air with three filter layers, wherein the filter layers are arranged in a common frame composed of extruded profile strips. One of the filter layers comprises an adsorption filter designed as a honeycomb body, while the two other filter layers comprise particle filters. The particle filter layers comprise separate filter bellows through which air can flow in series, one of the filter bellows comprising a HEPA filter medium. The profile strips of the frame hold the multiple filter layers on the inside, and the filter module is sealed externally in a housing via the frame. The filter module further comprises a circumferential sealing flange formed on the profile strips, which projects radially outward in the region of the two particle filter elements. Projecting inward, the profile strips further have two circumferential collar sections, on which two of the filter layers are supported in each case.This design, in combination with the design of the particle filter layers as separate filter bellows, requires a comparatively large installation space in the axial direction.

[0009] The disadvantage is the comparatively complex structure and the associated high material usage and manufacturing costs. Furthermore, the material mix used poses a disposal problem, as purely thermal recycling is not possible.

[0010] Furthermore, WO 2015 / 092681 A1 discloses a filter element with two filter bellows through which flow can be conducted in series, both comprising a cellulose-based filter medium. The two filter bellows adjoin one another in a joint area and are held at a predetermined distance in the flow direction by a spacer. The two filter bellows have the same dimensions transverse to the flow direction and are connected by a common circumferential seal made of a PUR material, which is connected to the side surfaces of both filter bellows in the joint area. The disadvantage of this is that the connection between the two filter bellows is not sufficiently resilient, which is particularly problematic in the case of vibrations occurring during operation.

[0011] It is therefore desirable to create a filter element that integrates multiple filter stages and is more mechanically resilient than known multi-stage filter elements. Disclosure of the invention

[0012] Against this background, the present invention is based on the object of creating an improved filter element.

[0013] This object is achieved by a filter element having the features of claim 1 and by a filter device having the features of claim 17. Further embodiments of the invention are the subject of the subclaims and the exemplary embodiments of the invention described below.

[0014] A filter element according to the invention is, in particular, an air filter element for an air filter system, in particular for a cabin air filter system or an intake air filter system of a fuel cell. The filter element comprises two filter bellows that are arranged adjacent to one another in a predetermined flow direction such that air can flow through them in series. The filter bellows each have an inflow and outflow surface and at least four side surfaces. The filter bellows adjoin one another in an interface region between the outflow surface of a first filter bellows and the inflow surface of a second filter bellows. In the interface region, there is a circumferential seal that directly connects the two filter bellows to one another in a materially bonded manner.One of the filter bellows has a smaller extension in at least one direction transverse to the flow direction than the other filter bellows, wherein the filter bellows are arranged relative to one another in at least one direction transverse to the flow direction such that along at least one edge of the larger filter bellows in the interface region, there is a free space at the inflow or outflow surface of the larger filter bellows that is not covered by the smaller filter bellows. The circumferential seal is directly bonded to the inflow or outflow surface of the larger filter bellows in the region of the free space.

[0015] Accordingly, the mechanical strength of the connection between the two filter bellows is significantly improved in the filter element according to the invention. This is achieved, among other things, by larger contact surfaces of the integrally formed, circumferential seal with the filter bellows. Furthermore, the molding of the circumferential seal to the inflow or outflow surface of the larger filter bellows also improves the rigidity of the entire filter element, which improves its handling, particularly during servicing. "Free space" refers to an imaginary area that remains in the interface area at the inflow or outflow surface of the larger filter element due to the smaller dimensions of one filter element relative to the other.However, the circumferential seal is installed in this imaginary free space in the finished filter element, so that the area does not remain free, but is to be understood as an aid to describe the structural design of the filter element.

[0016] Advantageously, the filter element according to the invention can consist entirely of thermally recyclable materials, so that no disposal problems arise and, in particular, dismantling of individual components of the filter element in the recycling cycle is not necessary.

[0017] In some embodiments, the filter bellows and / or the filter element itself are each cuboid-shaped. Cuboid-shaped components can be conveniently assembled to form the filter element and allow for efficient use of installation space.

[0018] Furthermore, especially in the case of cuboid-shaped external dimensions, symmetries related to certain planes through the filter element can arise, which allow a favorable mass distribution of the filter element.

[0019] Here, we speak of an axial direction and a radial direction of the filter element, where "axial" is understood to mean the flow direction, i.e., perpendicular to an inflow surface or side of the, for example, cuboid-shaped filter element. "Radial" is understood, in particular, to mean a normal direction of a side surface or wall of the frame or a lateral surface of the, in particular, cuboid-shaped, filter element.

[0020] The respective filter bellows can comprise a filter medium, which can be, for example, a filter fabric, a filter scrim, or a filter fleece. In particular, the filter medium can be produced using a spunbond or meltblown process. Furthermore, the filter medium can be felted or needle-punched. The filter medium can comprise natural fibers, such as cotton, or synthetic fibers, for example, made of polyester, polyphenyl sulfide, or polytetrafluoroethylene. To form the respective filter bellows, the filter medium is folded or corrugated several times. The pleat spacing of the filter bellows can, for example, be between 3 and 5 mm, and the pleat height between 20 and 30 mm. In embodiments, there can be between 30 and 300 pleats.

[0021] The filter element according to the invention is suitable as a replaceable component for an air filter system, in particular for a cabin air filter system or an intake air filter system of a fuel cell, and can be installed in a filter housing, in particular one that is fixed to the vehicle.

[0022] In some embodiments, the circumferential seal on at least one edge of the larger filter bellows can also be directly connected by a material bond to at least one side surface of each of the two filter bellows. This further improves the load-bearing capacity of the connection between the two filter elements and increases the resulting rigidity of the filter element as a whole, particularly with respect to axial force loading and / or bending about an axis transverse to the flow direction.

[0023] In certain embodiments, the circumferential seal can comprise or consist of a plastic material, in particular a foamed polyurethane or a thermoplastic elastomer. The aforementioned materials can be readily provided in a liquid or pasty initial state and, with the aid of a casting shell, can be directly and firmly molded to both filter bellows in a material-to-material manner according to the invention. The sealing base material, provided in a liquid or pasty initial state, hardens in the casting shell and subsequently forms the final material of the circumferential seal.

[0024] According to a further embodiment, the circumferential seal can have at least three legs in cross section, namely

[0025] - a cross leg connected to the inflow or outflow surface of the larger filter bellows and

[0026] - a first longitudinal leg connected to the side surface of the smaller filter bellows and

[0027] - a second longitudinal leg, which is connected to the side surface of the larger filter bellows. Advantageously, all three legs of the circumferential seal can be produced in a single process step in a single tool (casting shell). The aforementioned legs—transverse leg, first longitudinal leg, and second longitudinal leg—can also be referred to as the connecting legs of the circumferential seal, as they primarily serve to connect the two filter bellows.

[0028] Furthermore, the circumferential seal can have a radially projecting circumferential sealing area designed to form a sealing contact with a housing sealing surface of a filter housing. The sealing area can have various cross-sections that appear suitable to a person skilled in the art, depending on the technical constraints of the filter housing. For example, the sealing area can be designed for radially or axially effective sealing and, alternatively or additionally, can have one or more sealing lips or sealing grooves. Advantageously, the sealing area can also be produced together with the connecting legs of the circumferential seal in a single process step by casting.

[0029] In some designs, the filter bellows can each have exactly four side surfaces, especially in a cuboid shape. However, other basic shapes of the filter bellows are also possible, in particular certain polygons, especially with more than five corners.

[0030] According to a preferred development, the smaller filter bellows can have a smaller extension in at least one further direction transverse to the flow direction than the other filter bellows, wherein the filter bellows are arranged relative to one another in the at least one further direction transverse to the flow direction in such a way that along at least one further edge of the larger filter bellows in the interface region there is a free space on the inflow or outflow surface of the larger filter bellows, which is not covered by the smaller filter bellows, wherein the circumferential seal in the region of the free space is directly materially connected to the inflow or outflow surface of the larger filter bellows.

[0031] In some embodiments, it is possible for a free space to remain on at least one pair of opposite edges of the inflow or outflow surface of the larger filter bellows. In other words, the smaller filter bellows can be offset from the pair of opposite edges of the larger filter bellows by a predetermined amount in two different directions running transversely to the flow direction. The connection of the circumferential seal to the inflow or outflow surface of the larger filter bellows in the region of the free space can be designed to be fully circumferential.

[0032] Furthermore, at least one of the filter bellows can have at least one particle filter medium, in particular comprising a synthetic nonwoven material and / or a cellulose-based filter medium, wherein the particle filter medium in particular meets filtration class H13 or H14 according to DIN EN 1822-1. Alternatively or additionally, at least one of the filter bellows can have at least one gas filter medium, in particular comprising at least one adsorbent, in particular activated carbon, a zeolite and / or an ion exchanger. The gas filter medium can also comprise its own particle filter layer, in particular comprising a synthetic nonwoven material. Alternatively, the gas filter medium can also have only a support layer that immobilizes the adsorbent provided in granular or particle form, wherein the support layer can have a nonwoven material with a comparatively significantly larger pore size than the particle filter medium.

[0033] According to a further preferred embodiment, the smaller filter bellows can contain the gas filter medium. On the one hand, this has the advantage that a larger filter surface can be provided in the filter bellows with the particle filter medium, which is particularly advantageous for high-efficiency particle filter media from the HEPA range. On the other hand, there is a further advantage that, due to the complete enclosure of an edge of the smaller filter bellows facing the larger filter bellows by the circumferential seal, any discharge of adsorbent, in particular activated carbon particles, to the outside can be effectively prevented. Should adsorbent particles become detached from the gas filter medium during operation, they do not escape into the environment but are, so to speak, trapped in the interface area.

[0034] In particular, the filter bellows containing the particle filter medium can be arranged upstream of the filter bellows containing the gas filter medium. Thus, an air flow passing through the filter element according to the invention can first flow through the filter bellows containing the particle filter medium and then through the filter bellows containing the gas filter medium. This has the advantage that air freed from particles can flow through the gas filter medium, which improves the adsorption performance of the gas filter medium, particularly over time, since the pores of the adsorbent of the gas filter medium are not "clogged" with particles.

[0035] Expressly independent of the above, it can be provided that the smaller filter bellows is arranged upstream and the larger filter bellows downstream.

[0036] Furthermore, the particle filter medium and / or gas filter medium can have an antimicrobial and / or antiallergenic effect. Examples of antimicrobial substances include zinc pyrithione or nanosilver, and examples of antiallergenic substances include polyphenols.

[0037] According to yet another embodiment, the smaller filter bellows can have an at least partially circumferential frame element, in particular comprising at least one side band attached to the pleat end edges of the filter bellows and / or at least one head band attached to an end pleat of the filter bellows. The side band and / or head band can comprise or consist of a synthetic nonwoven material. The side band is, in particular, sealed by adhesive bonding to the pleated profiles, and the head band also forms a tight seal with the pleated filter medium.

[0038] According to yet another embodiment, the circumferential seal can be directly connected to the at least partially circumferential frame element of the smaller filter bellows by means of a material bond. This further improves the mechanical strength of the connection between the two filter bellows and also has a beneficial effect on the rigidity of the filter element as a whole. Furthermore, in designs in which the smaller filter bellows contains the gas filter medium, the "enclosure" of the smaller filter bellows by the frame element can reduce the tendency for adsorbent particles present in the gas filter medium to be discharged.

[0039] Regardless of the design, the direct, material-to-material connection of the surrounding seal can be foamed, which is a process established on a large industrial scale, particularly when using polyurethane as the starting material. Alternatively or additionally, the larger filter bellows can have sealed pleat edges, particularly in the form of a fluid-tight bond between pleat spaces and / or at least one frame element attached to the pleat edges. The sealed edges prevent bypassing of the filter medium of the larger filter bellows.

[0040] Furthermore, a spacer element can be present in the interface area, which defines a distance between the two filter bellows in the flow direction. The spacer element can, in particular, extend with at least one component transverse to a pleat length of at least one of the filter bellows to enable optimal support at as many contact points as possible. A distance between the two filter bellows is generally advantageous to achieve uniform flow through both filter bellows. However, the spacer element not only serves to support the two filter elements against each other, but also fulfills a stabilizing function for the filter element as a whole.

[0041] The spacer element can comprise a trace of adhesive applied to a plurality of pleat tips of at least one of the filter bellows, at least one thread bonded to the pleat tips, and / or a grid arranged in the interface area. The grid can be made of a plastic material and, in particular, can be provided as an injection-molded part; this allows a particularly good stiffening effect of the spacer element to be achieved.

[0042] In embodiments, the grid can have an at least partially circumferential collar portion that projects radially beyond the larger filter bellows. However, the collar portion of the grid preferably extends completely around the circumference. The collar portion of the grid can, in particular, be embedded in a material of the circumferential seal, preferably foam-encased in a material of the circumferential seal. The collar portion of the grid can, in particular, be completely surrounded by the material of the circumferential seal.

[0043] The collar section of the grid can, in particular, extend at least partially in the plane in which the interface area lies. In some embodiments, however, the collar section of the grid can also be angled at least partially relative to the plane of the interface area, in particular to internally stiffen a sealing area of ​​the circumferential seal. In some embodiments, the collar section of the grid can be angled in a direction pointing toward the larger filter bellows.

[0044] In particular, the collar section is made of one piece with the material of the grid and can be manufactured in a common process step with the grid.

[0045] Additionally, at least a portion of the grid can extend radially beyond the collar portion and form an at least partially circumferential overhanging edge beyond the circumferential seal. However, the overhanging edge preferably extends completely around the circumference. The overhanging edge is, in particular, integrally formed with the material of the grid and / or the collar portion and can be manufactured in a single process step with the grid and / or the collar portion.

[0046] The collar section and / or the overhanging edge are preferably made of a stiffer material than the circumferential seal, in particular of a plastic material, in particular of an injection-moldable plastic material.

[0047] The overhanging edge provides additional stiffening for the filter element; at least one fastening device can be molded onto it, by means of which the filter element can be held in a filter housing. The fastening device can be, for example, a tab that includes at least one fastening element, such as a screw-through opening or a snap-in element.

[0048] The filter bellows can have different pleat spacings, whereby a pleat spacing of the smaller filter bellows can be larger than a pleat spacing of the larger filter bellows. Alternatively, a pleat spacing in the filter bellows comprising the gas filter medium can be larger than a pleat spacing in the filter bellows comprising the particle filter medium.

[0049] A further aspect of the present invention relates to a filter device, in particular a cabin air filter system or an intake air filter system of a fuel cell. The filter device comprises a filter housing with two housing parts, at least one of which has a filter element receiving space in which a filter element according to the invention is arranged. The filter housing has at least one circumferential housing sealing surface against which a circumferential seal of the filter element sealingly rests.

[0050] In embodiments, it can be provided that the circumferential seal between the two housing parts is axially pressed when the filter element is arranged as intended in the filter housing.

[0051] Further possible implementations of the invention also include combinations of features not explicitly mentioned above or below with regard to the exemplary embodiments. In this case, the person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the invention.

[0052] The invention will be explained in more detail below using exemplary embodiments with reference to the attached figures.

[0053] Short description of the drawings

[0054] They show:

[0055] Fig. 1 is an isometric view of a filter element according to the invention;

[0056] Fig. 2 is a plan view of the filter element according to the invention;

[0057] Fig. 3 section AA according to Fig. 2;

[0058] Fig. 4 is a side view of the filter element according to the invention with cutout;

[0059] Fig. 5 Detail Z according to Fig. 4;

[0060] Fig. 6 is a longitudinal sectional view of a filter device according to the invention;

[0061] Fig. 7 is a sectional view of a filter element according to the invention according to a further embodiment;

[0062] Fig. 8 is a sectional view of a filter element according to the invention according to yet another embodiment.

[0063] Embodiment(s) of the invention

[0064] Fig. 1 shows the filter element 10 according to the invention in an isometric view. The filter element 10 comprises two filter bellows 1, 2, each with a filter medium arranged in folds 15, 25, wherein the filter bellows 1, 2 are arranged adjacent to one another in the direction of a designated flow direction D, so that flow can pass through them in series. The filter bellows 1, 2 each have an inflow 11, 21 and outflow surface 12, 22 (see Fig. 3) as well as four side surfaces 13, 14, 23, 24. The folded filter medium of the filter bellows 1, 2 has pleat front edges 15', 25' at the longitudinal ends of the pleats 15, 25 (see Fig. 4). The first filter bellows 1 is arranged upstream of the second filter bellows 2. The first filter bellows 1 comprises, in particular, a filter medium for gas filtration, in particular with activated carbon as adsorbent; the second filter bellows 2 comprises, in particular, exclusively a particle filter medium.

[0065] The folded filter medium of the first filter bellows 1 is provided with a side band 131 at each of its pleat end edges 15' (see Fig. 4) and with a head band 141 at each of its end folds. The side bands 131 and head bands 141 represent a circumferential frame element which encloses the folded filter medium 15 of the first filter bellows 1.

[0066] The basic shape of both the filter element 10 as a whole and the filter bellows 1, 2 is cuboid-shaped, with a pronounced long side and a pronounced short side.

[0067] The filter element 10 further comprises a circumferential seal 3, which connects both filter bellows 1, 2 and is directly integrally formed, in particular foamed, thereto.

[0068] The second filter bellows 2 has sealed pleat end edges 25', which are implemented in the form of a fluid-tight bond between pleat spaces 251 (see Fig. 4). Alternatively, a frame element applied to the pleat end edges 25' of the filter medium of the second filter bellows 2 can also be provided for sealing the pleat end edges.

[0069] The first filter bellows 1 is smaller than the second filter bellows 2, where “smaller” refers to its dimensions transverse to the flow direction D.

[0070] Fig. 2 shows the filter element 10 according to the invention in a plan view, with the first filter bellows 1 at the top.

[0071] Fig. 3 shows a section in the sectional plane AA shown in Fig. 2, which runs parallel to the short sides 14, 24 of the filter element 10. Fig. 3 shows the internal structure of the filter element 10, in particular the connection of the two filter bellows 1, 2 by the circumferential seal 3. The filter bellows 1, 2 border on one another in an interface region S between the outflow surface 12 of the first filter bellows 1 and the inflow surface 21 of the second filter bellows 2. The filter bellows 1, 2 are held at a predetermined distance from one another in the flow direction D by a spacer element 26. The spacer element 26 extends transversely to the longitudinal extent of the folds of at least one of the filter bellows 1, 2. The spacer element 26 is in particular a trace of adhesive applied to a plurality of pleat tips 27 of the second filter bellows 2 or a thread glued to the pleat tips 27.

[0072] Since the first filter bellows 1 is smaller than the second filter bellows 2, a free space F remains at opposite edges of the larger filter bellows 2 on its inflow surface 21 in the interface area S, which is not covered by the first filter bellows 1. The smaller first filter bellows 1 is arranged offset such that a free space F is present at the opposite edges of the larger second filter bellows 2, wherein in particular the respective free spaces F at the opposite edges of the larger second filter bellows 2 have the same dimensions.

[0073] In the area of ​​the free space F, the circumferential seal 3 is directly connected by a material fit to the inflow surface 21 of the larger filter bellows 2. Furthermore, the circumferential seal 3 is directly connected by a material fit to the side surfaces 13, 14 (see Fig. 4) of the first, smaller filter bellows 1 and to the side surfaces 23, 24 (see Fig. 4) of the second, larger filter bellows 2.

[0074] The two filter bellows 1, 2 are therefore connected to each other via the circumferential seal 3.

[0075] Since the connection is made via the respective side surfaces 13, 14, 23, 24 of the two filter bellows 1, 2 as well as via the inflow surface 21 of the second filter bellows 2, the contact area of ​​the circumferential seal 3 with the filter bellows 1, 2 is maximized, which contributes to a mechanically very resilient connection. The connection via the respective side surfaces 13, 14, 23, 24 of the two filter bellows 1, 2 as well as via the inflow surface 21 of the second filter bellows 2 is preferably completely circumferential.

[0076] In a radially projecting region of the circumferential seal 3 there is a sealing region 31 which, in an assembled state of the filter element 10, comes into contact with at least one sealing surface on the housing side.

[0077] In Fig. 4, which shows the filter element 10 in a side view in a projection direction along the short side surfaces 14, 24, the connection of the spacer element 26 to the pleat tips 27 of the second filter bellows 2 can be seen in particular.

[0078] Further details are explained with reference to detail Z shown in Fig. 5.

[0079] The circumferential seal 3 therefore has a first longitudinal leg 33, which is connected to the side surface 14 of the first filter bellows 1. More precisely, the first longitudinal leg 33 is connected to a headband 141 present on the side surface 14, which is present at an end fold of the folded filter medium of the first filter bellows 1. Furthermore, the circumferential seal 3 has a second longitudinal leg 34, which is connected to the side surface 24 of the second filter bellows 2. More precisely, the second longitudinal leg 34 is connected to an end fold of the filter medium of the second filter bellows 2. Finally, the circumferential seal 3 also has a transverse leg 32, which is connected to the inflow surface 21 of the second filter bellows 2. Furthermore, the transverse leg 32 is advantageously connected to an abutting surface of the headband 141 of the first filter bellows 1.Analogously, the transverse leg 32 can also advantageously be connected to an abutting surface of the side band 131 of the first filter bellows 1, which is shown in Fig. 3. A "butting surface" is understood to mean an axially directed cover surface.

[0080] Due to the above-described connection of the circumferential seal 3 with different contact surfaces of the two filter bellows 1, 2 and the T-shape resulting from the longitudinal legs 33, 34 and transverse legs 32 of the circumferential seal 3 in the connection area of ​​the two filter bellows 1, 2, the rigidity of the entire filter element 10 is advantageously significantly increased. The arrangement of the spacer element 26 in the interface area S further contributes to the rigidity, particularly with regard to bending about an axis transverse to the flow direction D.

[0081] Finally, Fig. 6 shows an installed state of the filter element 10 according to the invention in a filter housing 4 of an air filter system 100, in particular a cabin air filter system or an intake air filter system of a fuel cell. The filter housing 4 comprises two housing parts 41, 42, which together define a filter element receiving space. The lower housing part 41 can be a housing pan, and the upper housing part 42 can be a housing cover.

[0082] Both the first housing part 41 and the second housing part 42 each provide circumferential sealing surfaces 411, 421 against which the sealing region 31 of the circumferential seal 3 of the filter element 1 bears in a sealing manner. The sealing region 31 of the circumferential seal 3 is axially clamped between the housing parts 41, 42 via respective axial contact surfaces facing the sealing surface 411 of the first housing part 41 and the sealing surface 421 of the first housing part 42. In order to improve the force transmission to the sealing region 3 of the circumferential seal 3, at least one of the housing parts 41, 42 has a circumferential rib which presses against the respective axially directed contact surface of the sealing region 31.

[0083] Fig. 7 shows a longitudinal sectional view of a filter element 10 according to a further embodiment of the invention. The filter element 10 essentially corresponds to the filter element 10 shown in Figs. 1 to 5, so that the features, feature combinations, and their specific technical advantages described with respect to this filter element 10 and to the filter device 100 of Fig. 6 are transferable. Only the differences will be discussed below.

[0084] The spacer element 26 comprises a grid 26", which is present in the interface area S between the two filter bellows 1, 2. The grid 26' is fluid-permeable and in particular has a plurality of grid openings, between which grid webs extend, which bear against respective fold tips of the filter bellows 1, 2 pointing towards the interface area S in order to space the filter bellows 1, 2 at a predetermined distance. The grid 26" has a circumferential collar section 261 which projects radially over the larger filter bellows 2. The collar section 261 of the grid 26" is embedded in the material of the circumferential seal 3, in particular is foamed around it with the material of the circumferential seal 3. The collar section 261 of the grid 26" is in particular completely, ie on all sides, surrounded by the material of the circumferential seal 3.

[0085] The collar section 261 of the grid 26" extends with a first section in the plane in which the interface region S lies. In a second section, the collar section 261 is angled relative to the plane of the interface region S in order to internally stiffen a sealing region 31 of the circumferential seal 3. According to the exemplary embodiment, the collar section 261 of the grid 26" is angled in a direction pointing towards the larger filter bellows 2. The angled second section can have a bend, curvature, or kink. The collar section 261 is made in one piece with the material of the grid 26" and is manufactured in particular in a common process step together with the grid 26".

[0086] During production of the filter element 10, the grid 26" with the collar section 261 formed thereon is first provided, and then the two filter bellows 1, 2 are arranged thereon. In a subsequent step, the two filter bellows 1, 2 are connected by foaming or casting the circumferential seal 3, whereby the sealing section 31 is also formed and the collar section 261 is surrounded by the material of the circumferential seal 3. The foaming or casting can be carried out using a foaming or casting mold which has a negative contour of the circumferential seal 3.

[0087] In addition, at least a section of the grid 26" can extend radially beyond the collar section 261 and form an at least partially circumferential projecting edge 262 beyond the circumferential seal 3, which is shown in the longitudinal sectional view of the embodiment according to Fig. 8. The projecting edge 262 is not surrounded by the material of the circumferential seal 3 and is in particular exposed. In particular, the projecting edge 262 runs completely along the circumferential seal 3. The projecting edge 262 is made in one piece with the material of the grid 26" and the collar section 261 and can be manufactured in a common process step with the grid 26" and the collar section 261. The projecting edge 262 is in particular designed as a collar and is angled relative to a plane of the interface region S.The overhanging edge 262 is in particular angled in a direction opposite to the angled second section of the collar section 261.

[0088] The projecting edge 262 stiffens the filter element 10 on the one hand; on the other hand, a fastening device can be formed onto the projecting edge 262, by means of which the filter element 10 can be held in a filter housing. The fastening device can be, for example, a tab that includes at least one fastening element, for example a screw-through opening or a snap-in element, which, however, is not shown in the figure. Reference numerals used

[0089] 100 filter device

[0090] 10 filter element

[0091] 1 First filter bellows

[0092] 11 Inflow side of the first filter bellows

[0093] 12 Downstream side of the first filter bellows

[0094] 13,14 Side surfaces of the first filter bellows

[0095] 131 Sideband of the first filter bellows

[0096] 141 Headband of the first filter bellows

[0097] 15 folds of the first filter bellows

[0098] 15' pleat front edges of the first filter bellows

[0099] 2 Second filter bellows

[0100] 21 Inflow side of the second filter bellows

[0101] 22 Downstream side of the second filter bellows

[0102] 23,24 Side surfaces of the second filter bellows

[0103] 25 folds of the second filter bellows

[0104] 25' pleat end edges of the second filter bellows

[0105] 251 Pleat spaces of the second filter bellows

[0106] 26 Spacer element

[0107] 26' adhesive trail

[0108] 26' grid

[0109] 261 Bund section of the grille

[0110] 262 Overhanging edge of the grille collar

[0111] 27 pleat tips of the second filter bellows

[0112] 3 um running seal

[0113] 31 Sealing area

[0114] 32 cross legs

[0115] 33 First longitudinal leg

[0116] 34 Second longitudinal leg

[0117] D Flow direction

[0118] F Free space

[0119] S Interface area

[0120] 4 filter housings

[0121] 41 First housing part

[0122] 411 around the running sealing surface of the first housing part

[0123] 42 Second housing part

[0124] 421 circumferential sealing surface of the second housing part

Claims

Claims filter element (10), in particular air filter element, for an air filter system, in particular cabin air filter system or intake air filter system of a fuel cell, - comprising two filter bellows (1, 2) which are arranged adjacent to one another in a predetermined flow direction (D) such that they can be flowed through serially, - wherein the filter bellows (1, 2) each have an inflow (11, 21) and outflow surface (12, 22) and at least four side surfaces (13, 14, 23, 24), - wherein the filter bellows (1, 2) adjoin one another in an interface region (S) between the outflow surface (12) of a first filter bellows (1) and the inflow surface (21) of a second filter bellows (2), - further comprising a circumferential seal (3) present in the interface region (S), which directly connects the two filter bellows (1, 2) to one another in a materially bonded manner, characterized in that one of the filter bellows (1, 2) has a smaller extension in at least one direction transverse to the flow direction (D) than the other filter bellows (1, 2), wherein the filter bellows (1, 2) are arranged relative to one another in the at least one direction transverse to the flow direction (D) in such a way that along at least one edge of the larger filter bellows (1, 2) in the interface region (S) there is a free space (F) on the inflow surface (11, 21) or outflow surface (12, 22) of the larger filter bellows (1, 2), which free space is not covered by the smaller filter bellows (1, 2), wherein the circumferential seal (3) in the region of the free space (F) is directly connected in a materially bonded manner to the inflow surface (11 ,21 ) or outflow surface (12,22) of the larger filter bellows (1 ,2).Filter element (10) according to claim 1, wherein the circumferential seal (3) on the at least one edge of the larger filter bellows (1, 2) is also directly materially connected to at least one side surface (13, 14, 23, 24) of both filter bellows (1, 2).

3. Filter element (10) according to claim 1 or 2, wherein the circumferential seal (3) comprises or consists of a plastic material, in particular a foamed polyurethane or a thermoplastic elastomer.

4. Filter element (10) according to one of the preceding claims, wherein the circumferential seal (3) has at least three legs (32, 33, 34) in cross section, - a transverse leg (32) which is connected to the inflow (11,21) or outflow surface (12,22) of the larger filter bellows (1,2) and - a first longitudinal leg (33) which is connected to the side surface (13, 14, 23, 24) of the smaller filter bellows (1, 2) and - a second longitudinal leg (34) which is connected to the side surface (13,14,23,24) of the larger filter bellows (1,2).

5. Filter element (10) according to one of the preceding claims, wherein the circumferential seal (3) has a radially projecting circumferential sealing region (31) which is designed to bear sealingly against a housing sealing surface (411, 421) of a filter housing (4).

6. Filter element (10) according to one of the preceding claims, wherein the filter bellows (1, 2) each have exactly four side surfaces (13, 14, 23, 24) and / or have a cuboid basic shape.

7. Filter element (10) according to one of the preceding claims, wherein the smaller filter bellows (1, 2) has a smaller extension in at least one further direction transverse to the flow direction (D) than the other filter bellows (1, 2), wherein the filter bellows (1, 2) are arranged relative to one another in the at least one further direction transverse to the flow direction (D) in such a way that along at least one further edge of the larger filter bellows (1, 2) in the interface region (S) there is a free space (F) on the inflow (11, 21) or outflow surface (12, 22) of the larger filter bellows (1, 2), which free space is not covered by the smaller filter bellows (1, 2), wherein the circumferential seal (3) in the region of the free space (F) is directly materially bonded to the inflow (11, 21) or outflow surface (12, 22) of the larger filter bellows (1 ,2) is connected.

8. Filter element (10) according to one of the preceding claims, wherein - at least one of the filter bellows (1, 2) has at least one particle filter medium, in particular comprising a synthetic nonwoven material and / or a cellulose-based filter medium, wherein in particular the particle filter medium meets filtration class H13 or H14 according to DIN EN 1822-1, and / or - at least one of the filter bellows (1, 2) has at least one gas filter medium, in particular comprising at least one adsorbent, in particular an activated carbon, a zeolite and / or an ion exchanger.

9. Filter element (10) according to claim 8, wherein the smaller filter bellows (1, 2) comprises the gas filter medium.

10. Filter element (10) according to one of the preceding claims, wherein the smaller filter bellows (1, 2) has an at least partially circumferential frame element (131, 141), in particular comprising at least one side band (131) attached to pleat end edges (15', 25') of the filter bellows (1, 2) and / or at least one head band (141) attached to an end fold of the filter bellows, wherein in particular the side and / or head band (131, 141) has or consists of a synthetic nonwoven material.

11. Filter element (10) according to claim 10, wherein the circumferential seal (3) is directly connected in a materially bonded manner to the at least partially circumferential frame element (131, 141) of the smaller filter bellows (1, 2).

12. Filter element (10) according to one of the preceding claims, wherein the direct material connection of the circumferential seal (3) is a foamed connection.

13. Filter element (10) according to one of the preceding claims, wherein the larger filter bellows (1, 2) has sealed pleat end edges (15', 25'), in particular a fluid-tight bonding of pleat interspaces (251) and / or at least one frame element attached to the pleat end edges (15', 25').

14. Filter element (10) according to one of the preceding claims, wherein in the interface region (S) there is a spacer element (26, 26', 26") which predetermines a distance between the two filter bellows (1, 2) in the flow direction (D), wherein the spacer element (26, 26', 26") extends in particular with at least one component transversely to a pleat longitudinal extent of at least one of the filter bellows (1, 2).

15. Filter element (10) according to claim 14, wherein the spacer element (26, 26', 26") comprises a trace of adhesive (26') applied to a plurality of pleat tips of at least one of the filter bellows (1, 2), at least one thread glued to the pleat tips and / or a grid (26") arranged in the interface region (S).

16. Filter element (10) according to one of the preceding claims, wherein the filter bellows (1, 2) have different pleat spacings, wherein in particular a pleat spacing of the smaller filter bellows (1, 2) is greater than a pleat spacing of the larger filter bellows (1, 2).

17. Filter device (100), in particular of a cabin air filter system or an intake air filter system of a fuel cell, comprising a filter housing (4) with two housing parts (41, 42), at least one of which has a filter element receiving space in which a filter element is arranged, wherein the filter housing (4) has at least one circumferential housing sealing surface (411, 421) against which a circumferential seal of the filter element bears in a sealing manner, characterized in that the filter element is a filter element (10) according to one of the preceding claims.

18. Filter device (100) according to claim 17, wherein the circumferential seal (3) is axially compressed between the two housing parts (41, 42) when the filter element (10) is arranged as intended in the filter housing (4).

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