Flat filter element comprising an inner and outer filter medium body arrangement

Abstract

The invention relates to a flat filter element comprising a plurality of filter medium bodies. An inner filter medium body is accommodated in a recess which is circumferentially delimited by at least one outer filter medium body. The inner and outer filter medium bodies are formed with mutually separate pieces of preferably pleated filter medium. The inner filter medium body is fastened to the outer filter medium body or bodies. Preferably, a connecting means used for fastening at the same time seals the inner and outer filter medium bodies with respect to one another.

Description

[0001] Flat filter element with an inner and outer filter medium body arrangement

[0002] This patent application claims priority from German patent application No. DE 102024101713.9, filed on January 22, 2024 with the German Patent and Trademark Office, the contents of which are hereby incorporated by reference.

[0003] Technical area

[0004] The invention relates to a flat filter element comprising an outer filter medium body arrangement with at least one outer filter medium body and an inner filter medium body arrangement with at least one inner filter medium body, wherein the two filter medium body arrangements can be flowed through in an axial direction.

[0005] State of the art

[0006] Such a flat filter element is used, for example, in the Toyota Corolla, series E1 1 (model year 1997-2001) as a cabin air filter and is designated, for example, with the part number 88508-12010; such a flat filter element is sold, for example, under the MANN-FILTER brand with the type designation CU 2015. In this flat filter element, several filter medium bodies are separated from one another by ribs of a frame. An inner filter medium body and adjacent outer filter medium bodies are formed from a continuous filter medium, with the inner filter medium body having a lower pleat height than the outer filter medium bodies. The one-piece design of the filter medium bodies limits geometric adaptation options.

[0007] EP 2 981 700 B1 discloses an air filter element for an air filter device of a fresh air system of an internal combustion engine. The air filter element comprises two end plates which are spaced apart from one another in an axial direction of the air filter element. The air filter element has a U-shaped or horseshoe-shaped main filter body axially between the two end plates, which delimits an interior of the air filter element transversely to the axial direction. The two end plates hermetically seal two axial sides of the main filter body facing away from one another in the axial direction. Due to its U-shape, the main filter body has one open side. In the area of ​​this open side, the air filter element has a main passage opening open towards the interior, which can serve as an air outlet. At least one of the end plates has an additional passage opening open towards the interior, to which an additional filter body is assigned.Air can flow through the additional opening exclusively through the additional filter body. Air can flow through the additional filter body parallel to the axial direction.

[0008] DE 10 2016 217 339 A1 describes an air filter device with a filter housing which delimits a housing interior. The air filter device comprises a radially inner and a radially outer filter element, both of which are arranged interchangeably in the housing interior and separate a dirty side from a clean side. The radially inner filter element comprises an annular inner filter body made of filter material, extending along an axial direction. The radially outer filter element comprises an annular outer filter body made of filter material, extending along the axial direction. The inner filter body has a first structural height measured along the axial direction, and the outer filter body has a second structural height measured along the axial direction, which is different from the first structural height.

[0009] A filter element for an air filter is known from US Pat. No. 6,312,489 B1. The filter element consists of a zigzag-folded filter insert made of filter paper or filter fleece and a seal that runs along the outer edges of a flat side of the filter insert and with which the filter element rests against housing parts of a filter housing. The folded filter insert has a contour on one side that deviates from a plane at least in predetermined areas, and a continuous zigzag fold.

[0010] It is an object of the invention to enable the installation of filter elements with a large filter capacity in complex-shaped installation spaces.

[0011] Disclosure of the invention

[0012] This object is achieved by a flat filter element according to claim 1 and an air filter according to claim 19. Preferred embodiments are specified in the respective subclaims and the description.

[0013] According to the invention, a flat filter element is provided. The flat filter element is, in particular, an air filter element, preferably for an intake air filter of an internal combustion engine or fuel cell, or for a cabin air filter.

[0014] The flat filter element comprises an outer filter medium body arrangement with at least one outer filter medium body and an inner filter medium body arrangement with at least one inner filter medium body. The inner filter medium body arrangement typically comprises precisely one inner filter medium body. Flow can pass through the two filter medium body arrangements in an axial direction. A main extension of the filter medium body arrangements runs essentially transversely to the axial direction or main flow direction. The at least one inner filter medium body and / or the at least one outer filter medium body can comprise multiply pleated filter medium.

[0015] According to the invention, the inner filter medium body arrangement is formed separately from the outer filter medium body arrangement. In particular, the at least one inner filter medium body is formed separately from the at least one outer filter medium body. In other words, the inner filter medium body arrangement and the outer filter medium body arrangement are formed with mutually independent pieces of filter medium. If one of the filter medium body arrangements has multiple filter medium bodies, these can be formed with a continuous piece of filter medium. However, the filter medium bodies of the inner and outer filter medium body arrangements are not formed by a common piece of filter medium and are therefore not integral with one another. It is understood that the filter medium bodies of the inner and outer filter medium body arrangements can nevertheless be formed with filter medium of the same type.

[0016] The inner filter medium body arrangement is inserted into a recess in the outer filter medium body arrangement. Thus, the at least one inner filter medium body is received in the recess of the outer filter medium arrangement. An edge of the recess formed by the outer filter medium body arrangement encloses the inner filter medium body arrangement. The inner filter medium body arrangement is preferably completely surrounded by the outer filter medium body arrangement in the plane of the main extension. The recess is preferably circumferentially closed. If the outer filter medium body arrangement comprises several outer filter medium bodies, the edge of the recess has interruptions at most in boundary regions of the outer filter medium bodies and is otherwise closed.

[0017] The recess and the inner filter medium body arrangement can be polygonal, in particular rectangular, circular, or elliptical in shape. An outer periphery of the outer filter medium body arrangement can be rectangular in shape.

[0018] Further according to the invention, the outer filter medium body assembly and the inner filter medium body assembly are connected to one another via a connecting means. Thus, the at least one filter medium body of the inner filter medium body assembly is held to the at least one filter medium body of the outer filter medium body assembly. The connecting means is typically arranged at the edge of the recess and can engage between the inner and outer filter medium bodies.

[0019] The outer filter medium body arrangement has an axial extension along the circumference of the recess which corresponds to a multiple, in particular at least 5 times, preferably at least 10 times, of the thickness of a filter medium from which the at least one outer filter medium body is formed. This can increase the separation efficiency of the outer filter medium body arrangement. It is also possible to reduce the pressure drop across the outer filter medium body arrangement. In other words, the thickness (measured in the axial direction) of the at least one outer filter medium body is greater than the thickness of the filter medium from which the outer filter medium body is obtained. If the outer filter medium body arrangement comprises a plurality of outer filter medium bodies, the axial extension of each of the outer filter medium bodies is preferably greater than the thickness of the respective filter medium.The plurality of outer filter medium bodies can be formed from a filter medium of the same type, in particular of the same thickness. The at least one outer filter medium body can be obtained, in particular, by folding a filter medium multiple times.

[0020] By designing the flat filter element with multiple filter medium bodies, the flat filter element can be adapted to the available installation space. Since, according to the invention, an inner filter medium body is separate from the outer filter medium body arrangement, the shape adaptation can take place in the inner region of the outer filter medium body arrangement—the region of the recess. The separate design of the inner and outer filter medium bodies allows for particularly great flexibility in the design of the flat filter element. Furthermore, production can be simplified by providing the inner and outer filter medium bodies independently of one another and then attaching them to one another using the connecting means. The connecting means can also stabilize the flat filter element.

[0021] The outer filter media body assembly may comprise exactly one outer filter media body. This can simplify manufacturing.

[0022] Alternatively, the outer filter medium body arrangement can comprise several, preferably exactly two, outer filter medium bodies. This increases flexibility when adapting to particularly complex-shaped installation spaces. In particular, the outer filter medium bodies can have the same or different axial extensions. The two outer filter medium bodies can each be L-shaped. In this way, the recess for receiving the inner filter medium body arrangement can be easily obtained by arranging the two outer filter medium bodies next to one another.

[0023] The inner filter medium body arrangement and the outer filter medium body arrangement can have the same axial extension. Such similar filter medium bodies can be manufactured particularly efficiently.

[0024] Alternatively, the inner filter medium body arrangement and the outer filter medium body arrangement can have different axial extensions, at least in sections. This increases the flexibility when adapting to the shape of the available installation space while simultaneously achieving high filter performance. In particular, the inner filter medium body arrangement can have a smaller axial extension, at least in sections, than the outer filter medium body arrangement. Alternatively or additionally, the inner filter medium body arrangement can have a greater axial extension, at least in sections, than the outer filter medium body arrangement. Inflow and / or outflow surfaces of the inner filter medium body arrangement and the outer filter medium body arrangement can each extend orthogonally to the axial direction. The inflow and / or outflow surfaces of the inner filter medium body arrangement and the outer filter medium body arrangement, which extend orthogonally to the axial direction,the outer filter medium body arrangement therefore run parallel to each other.

[0025] The outflow surfaces and / or inflow surfaces of the inner filter media body assembly and the outer filter media body assembly can lie in a common plane. This can simplify the installation of seals to seal the outer and inner filter media body assemblies against each other and against a housing. Preferably, the clean-side outflow surfaces extend in a common plane.

[0026] The inflow and / or outflow surfaces of the inner filter medium body assembly and the outer filter medium body assembly can be offset from one another in the axial direction, preferably extending in mutually parallel planes. This can contribute to improved space utilization. The inflow surfaces on the raw side are preferably offset from one another.

[0027] The at least one inner filter medium body can protrude beyond the at least one outer filter medium body at least partially in the axial direction on the upstream and / or downstream sides. Alternatively or additionally, the at least one inner filter medium body can be set back behind the at least one outer filter medium body at least partially in the axial direction on the upstream and / or downstream sides. These configurations can also be advantageous with regard to space utilization.

[0028] Preferably, the connecting means extends over the entire circumference of the recess. This allows for a particularly stable attachment of the inner and outer filter media bodies to one another. Furthermore, this simplifies the formation of an internal seal by the connecting means.

[0029] Advantageously, the connecting element forms a circumferential inner seal. This inner seal prevents the passage of unfiltered air between the inner and outer filter media body assemblies. Because the connecting element not only secures the filter media body assemblies to one another but also seals them against one another, manufacturing costs can be reduced.

[0030] The connecting means is preferably made of a plastic, in particular polyurethane (PUR). This enables cost-effective production. Furthermore, polyurethane, in particular polyurethane foam, has good sealing properties. Particularly preferably, the connecting means is molded, in particular foamed, onto the inner filter medium body assembly and the outer filter medium body assembly. This enables particularly efficient production.

[0031] A circumferential outer seal can be arranged on the outer periphery of the outer filter media body assembly. The outer seal enables the flat filter element to be sealed against a housing and, optionally, also between housing parts.

[0032] The outer seal is preferably made of a plastic, especially polyurethane. This allows for cost-effective production. Furthermore, polyurethane, especially polyurethane foam, has good sealing properties.

[0033] Particularly preferably, the outer seal is molded, in particular foamed, onto the outer filter medium body assembly. This enables particularly efficient production.

[0034] The inner seal and the outer seal can be arranged on the same side of the flat filter element, preferably on the downstream side. In particular, the two seals can extend in a common sealing plane. This can simplify production by producing both seals in a single operation, particularly using a common casting shell. Furthermore, the design of the housing and the assembly of the flat filter element in the housing can be simplified.

[0035] A gap, in particular a continuous, circumferential gap, can be formed between the inner filter medium body assembly and the outer filter medium body assembly. The connecting element preferably engages in the gap. In particular, the connecting element can bridge the gap. The connecting element can extend in the gap, preferably over its entire length. The gap enables the engagement of housing parts between the inner and outer filter medium body assembly to support the flat filter element.

[0036] The at least one inner filter medium body and / or the at least one outer filter medium body can comprise pleated filter medium. This can increase the effective area of ​​the filter medium body. At the same time, pleating can increase the axial extent (thickness), in particular of the at least one outer filter medium body, relative to the filter medium.

[0037] Folded edges of the at least one inner filter medium body and the at least one outer filter medium body can extend parallel to one another or at an angle, in particular at an angle of 90°, to one another. Depending on the installation situation, this can allow optimal adaptation to the available installation space, for example by varying the axial extents of the inner and outer filter medium bodies in different directions. It can be provided that an axial extent of the inner filter medium body arrangement and / or the outer filter medium body arrangement changes along a transverse direction. This change in thickness within the respective filter medium body arrangement or within the respective filter medium body can be brought about by a variable pleat height.With a filter medium body whose thickness changes transversely to the main flow direction, a particularly large amount of filter medium can be accommodated in a non-cuboidal installation space.

[0038] A filter medium of the inner filter medium body assembly and / or the outer filter medium body assembly can be a filter paper or filter fleece, in particular a multi-layer filter paper or filter fleece. Such filter media are particularly suitable for the production of pleated filter medium bodies.

[0039] A filter medium of the inner filter medium body assembly and / or the outer filter medium body assembly can contain an adsorbent, particularly activated carbon. In particular, activated carbon particles can be enclosed between layers of filter material (e.g., filter paper or filter fleece). Adsorbents enable the retention of harmful gases. This can be particularly desirable for air filters for fuel cells or cabin air filters.

[0040] Also within the scope of the present invention is an air filter comprising a flat filter element according to the invention as described above and a preferably multi-part housing in which the flat filter element can be arranged. Because the housing follows the shape of the flat filter element, the air filter can be adapted to a complex shape in a limited installation space.

[0041] When installed, the flat filter element separates a raw side from a clean side in the housing.

[0042] The housing can have two housing parts that can be fastened to one another. A raw air inlet can be formed on a first of the housing parts. A clean air outlet can be formed on a second of the housing parts. However, it is also conceivable for both the raw air inlet and the clean air outlet to be formed on the same housing part.

[0043] A first housing part of the housing can have at least one support strut, which, when assembled, rests against the connecting means, particularly on the upstream side. The support strut preferably engages in a gap between the inner filter medium body assembly and the outer filter medium body assembly. The support strut can support and position the flat filter element in the housing. Furthermore, the support strut can help guide the air flow to be filtered.

[0044] A second housing part of the housing can have at least one support projection, which, when installed, rests against the connecting means, particularly on the downstream side. The support projection can support and position the flat filter element in the housing. Furthermore, the support projection can help guide the filtered airflow.

[0045] Preferably, the connecting means is clamped between the at least one support strut and the at least one support projection in the assembled state. This allows the flat filter element to be aligned particularly precisely and held securely. Preferably, contact surfaces of the at least one support strut and the at least one support projection with the connecting means overlap one another when viewed along the axial direction.

[0046] When assembled, an outer seal running around the outer perimeter of the outer filter media body assembly can seal two housing sections against each other. At the same time, the outer seal seals the flat filter element against the housing. This eliminates the need for separate sealing of the housing sections.

[0047] The housing can have an indentation extending from a housing wall to the inner filter medium body assembly. The indentation allows engagement of an interfering contour present in the installation space. Within the housing, the indentation is typically capable of flow around it. Thus, the entire flat filter element remains involved in air filtration. Preferably, the indentation ends at a distance from the inner filter medium body assembly. This is advantageous for air flow, as the inflow and outflow surfaces of the inner filter medium body are not covered. The indentation can be provided to support the inner filter medium body assembly, at least under particular loads, such as violent vibrations. This can prevent damage to the flat filter element.

[0048] Short 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 patent claims, and from the figures of the drawing, which illustrate details of the invention. The features mentioned above and those further described can be implemented individually or in combination in any suitable way in variants of the invention. The features shown in the drawing are presented in such a way that the special features of the invention can be clearly seen.

[0050] The drawing shows:

[0051] Fig. 1 shows a first flat filter element according to the invention with an inner filter medium body arranged in a recess of an outer filter medium body, in a schematic perspective view looking downstream; Fig. 2 shows the flat filter element of Fig. 1, in a schematic perspective view looking downstream, with the two filter medium bodies flush with one another on the upstream side;

[0052] Fig. 3 shows a first housing part of a housing for receiving the flat filter element of Fig. 1, in a schematic perspective view;

[0053] Fig. 4 shows a second housing part of the housing for receiving the flat filter element of Figure 1, in a schematic perspective view;

[0054] Fig. 5 an air filter according to the invention with a second inventive

[0055] Flat filter element in which an axial extension of an inner filter medium body is smaller than an axial extension of an outer filter medium body, in a schematic sectional view;

[0056] Fig. 6 shows a third flat filter element according to the invention with an outer filter medium body with fold heights increasing in a transverse direction and an inner filter medium body set back on the upstream side, in a schematic perspective view;

[0057] Fig. 7 shows a further air filter according to the invention with a fourth

[0058] Flat filter element in which an axial extension of an inner filter medium body is greater than an axial extension of an outer filter medium body, in a schematic sectional view;

[0059] Fig. 8 shows a fifth flat filter element according to the invention with an inner filter medium body with fold heights increasing in a transverse direction, which protrudes on the upstream side beyond an outer filter medium body, in a schematic side view;

[0060] Fig. 9 a sixth flat filter element according to the invention with an octagonal inner

[0061] Filter medium body arranged in a corresponding recess of an outer filter medium body, in a schematic perspective view looking towards a downstream side;

[0062] Fig. 10 shows the flat filter element of Fig. 9, in a schematic perspective view looking towards an upstream side, wherein the inner filter medium body protrudes above the outer filter medium body on the upstream side;

[0063] Fig. 1 1 shows a seventh flat filter element according to the invention with an inner filter medium body arranged in a recess of an outer filter medium body arrangement with two L-shaped outer filter medium bodies, in a schematic perspective view looking towards a downstream side;

[0064] Fig. 12 shows the flat filter element of Fig. 11 in a schematic perspective view looking onto an upstream side, wherein one of the outer filter medium bodies protrudes beyond the inner filter medium body and the inner filter medium body protrudes beyond the other outer filter medium body;

[0065] Fig. 13 shows a zigzag-folded filter medium for flat filter elements according to the invention, comprising two layers of filter material between which an adsorbent is arranged, in a schematic sectional view. Embodiments of the invention

[0066] Figures 1 and 2 show a flat filter element 10.1. The flat filter element 10.1 has an outer filter medium body assembly 12 and an inner filter medium body assembly 14. The outer filter medium body assembly 12 is formed here with exactly one outer filter medium body 16. The inner filter medium body assembly 14 is formed here with exactly one inner filter medium body 18.

[0067] The inner filter medium body assembly 14 or inner filter medium body 18 is arranged in a recess 20 of the outer filter medium body assembly 12 or outer filter medium body 16. The recess 20 is completely enclosed by the outer filter medium body assembly 12 or outer filter medium body 16. In this case, both filter medium body assemblies 12, 14 have a rectangular outer contour. Accordingly, the recess 20 is also rectangular.

[0068] The outer filter medium body 16 and the inner filter medium body 18 are each formed by folding flat filter media 22 and 24, respectively, such as filter paper or filter fleece. Folded edges 26, 28 of the outer and inner filter medium bodies 16, 18 run parallel to each other. Alternatively, the folded edges could run at an angle to each other, in particular orthogonally to each other (not shown in detail). The two filter medium bodies 16, 18 consist of separate pieces of the respective filter medium 22, 24.

[0069] In the illustrated embodiment, the two filter medium bodies 16, 18 each have a constant axial extension 30, 32 across their entire length. Due to the folding, the axial extension 30, 32 of both filter medium bodies 16, 18 is a multiple of the thickness 34, 36 of the respective filter medium 22, 24.

[0070] In this embodiment, the axial extents (thicknesses) 30, 32 of the two filter medium bodies 16, 18 are equal. A (clean-side) outflow surface 38 of the outer filter medium body 16 and an outflow surface 40 of the inner filter medium body 18 extend in a common plane, see Figure 1. A (dirty-side) inflow surface 42 of the outer filter medium body 16 and an inflow surface 44 of the inner filter medium body 18 extend in a common plane, which extends parallel to the plane of the outflow surfaces 38, 40, see Figure 2. The inflow surfaces 42, 44 and the outflow surfaces 38, 40 each extend perpendicular to a main flow direction or axial direction 46.

[0071] A continuous, circumferential gap 48 is formed between the two filter medium bodies 12, 14 at the edge of the recess 20 (see Figure 2). On the downstream side, the gap 48 is bridged by a connecting means 50 (see Figure 1). The connecting means 50 extends here over the entire circumference of the recess 20. The connecting means can be made of plastic, for example polyurethane, in particular polyurethane foam, and can be integrally connected to the filter medium bodies 16, 18, for example cast or foamed onto them. The connecting means 50 fixes the inner filter medium body arrangement 14 or the inner filter medium body 18 to the outer filter medium body arrangement 12 or the outer filter medium body 16. In addition, the connecting means 50 forms an inner seal 52 which seals the two filter medium body arrangements 12, 14 against each other in their boundary region, here along the gap 48.

[0072] An outer seal 54 is provided on the outer periphery of the outer filter medium body assembly 12, here also on the downstream side. The outer seal 54 can be made of plastic, for example polyurethane, in particular polyurethane foam, and can be integrally bonded to the filter medium body 16, for example, cast or foamed onto it.

[0073] For use, the flat filter element 10.1 is inserted into a housing 56, which here is formed with a first housing part 58 (see Figure 3) and a second housing part 60 (see Figure 4), which housing parts 56, 58 can be releasably secured to one another. In the assembled state, the outer seal 54 seals the two housing parts 58, 60 from one another and the flat filter element 10.1 from the housing 56. See also Figure 5, which shows an air filter 62.1 with a similar flat filter element 10.2.

[0074] A raw air inlet 64 is formed on the first housing part 58 (see also Figure 3). Furthermore, the first housing part 58 has several, here four, support struts 66. In the assembled state, the support struts 66 engage in the gap 48 and come into contact with the connecting means 50 on the raw side (see Figure 5).

[0075] In addition, in these embodiments, the first housing part 58 has an indentation 68 in a housing wall 70, here at the bottom. The indentation 68 forms an extended recess in the housing wall 70. In the area of ​​the indentation 68, the housing wall 70 is brought closer to the inner filter medium body assembly 14. The indentation 68 allows the engagement of an interfering contour 72 on the installation space side, such as a protruding component that restricts the installation space for the air filter 62.1. The air filter 62.1 or its housing 56 can thus encompass the interfering contour 72 without significantly limiting the filtering performance.

[0076] A clean air outlet 74 is formed on the second housing part 60 (see also Figure 4). Furthermore, the second housing part 60 has several, here four, support projections 76. In the assembled state, the support projections 76 rest on the connecting means 50 on the clean side (see Figure 5).

[0077] In the present case, the support struts 66 and the support projections 76 are each arranged in the region of the corners of the recess 20, so that they point toward each other. The connecting means 50 is clamped between the support struts 66 and the support projections 76 in the assembled state. The flat filter element 10.2 of the air filter 62.1 of Figure 5 corresponds in many aspects to the flat filter element 10.1 shown in Figures 1 and 2 and described above. The differences are primarily explained below; otherwise, reference is made to the above description.

[0078] In the flat filter element 10.2, the axial extension 32 of the inner filter medium body 18 of the inner filter medium body arrangement 14 is smaller, here approximately half, than the axial extension 30 of the outer filter medium body 16 of the outer filter medium body arrangement 12. Here, too, the outflow surfaces 38, 40 of the two filter medium bodies 16, 18 extend in a common plane. However, the inflow surface 44 of the inner filter medium body 18 is set back in the axial direction 46 relative to the inflow surface 42 of the outer filter medium body 16, with the two inflow surfaces 42, 44 extending in mutually parallel planes. Thus, part of the recess 20, here approximately its upstream half, is not filled by the inner filter medium body arrangement 18. The recess 68 of the housing 56 can therefore extend further inward than would be possible when using the flat filter element 10.1 of Figures 1 and 2. With the flat filter element 10.2, a comparatively widely projecting interference contour 72 can be accommodated or avoided. Since the axial extension of the flat filter element 10.2 is reduced only in the area of ​​the inner filter medium body arrangement 14, which covers a significantly smaller area compared to the outer filter medium body arrangement 12, the filter performance is only slightly reduced.

[0079] Figure 6 shows a flat filter element 10.3, which in many aspects corresponds to the flat filter element 10.2 of Figure 5. The differences are primarily explained below; otherwise, reference is made to the above description.

[0080] In the flat filter element 10.3, the inflow surface 42 of the outer filter medium body arrangement 12 is inclined relative to its outflow surface 38. Thus, the axial extent 30 varies along a transverse direction 78, which runs perpendicular to the folded edges 26 and the axial direction 46. The thickness of the outer filter medium body 16, which varies in the transverse direction 78, is caused by different pleat heights of the folds of the filter medium 22 arranged successively in the transverse direction 78.

[0081] The inflow surface 44 of the inner filter medium body arrangement 14 runs parallel to the two outflow surfaces 38, 40 extending in a common plane. The inflow surface 44 of the inner filter medium body 18 is recessed relative to the inflow surface 42 of the outer filter medium body 16 throughout the entire area of ​​the recess 20. The distance between the inflow surfaces 42, 44 changes in the transverse direction 78 according to the change in the axial extension 30 of the outer filter medium body 16.

[0082] Figure 7 shows another air filter 62.2, which in many aspects corresponds to the air filter 62.1 of Figure 5. The air filter 62.2 has a flat filter element 10.4, which in many aspects corresponds to the flat filter element 10.3 of Figure 5. The differences are primarily explained below; otherwise, reference is made to the above description.

[0083] In the flat filter element 10.4, the axial extension 32 of the inner filter medium body 18 of the inner filter medium body arrangement 14 is greater than, in this case approximately twice as large as, the axial extension 30 of the outer filter medium body 16 of the outer filter medium body arrangement 12. Here, too, the outflow surfaces 38, 40 of the two filter medium bodies 16, 18 extend in a common plane. However, the inflow surface 44 of the inner filter medium body 18 protrudes in the axial direction 46 relative to the inflow surface 42 of the outer filter medium body 16, with the two inflow surfaces 42, 44 extending in mutually parallel planes.

[0084] The indentation 68 can therefore protrude less far inward in the filter device 62.2 and accommodate only a smaller interfering contour 72 than in the filter device 62.1. However, the smaller axial extension 30 of the outer filter medium body 16 allows the housing wall 70, in the area facing away from the raw air inlet, to be provided with an indentation 80, which brings the housing wall 70 closer to the outer filter medium body 16. In the area of ​​the indentation 80, a further interfering contour 82 can be accommodated or bypassed by the housing 56. The further interfering contour 82 can be, for example, a pipe or hose.

[0085] The axial extension 32 enlarged in the area of ​​the inner filter medium body arrangement 14 increases the filter performance of the flat filter element 10.4 compared to a flat filter element which would consistently have only the smaller axial extension 30 of the outer filter medium body arrangement 12.

[0086] Figure 8 shows a flat filter element 10.5, which in many aspects corresponds to the flat filter element 10.4 of Figure 7. The differences are primarily explained below; otherwise, reference is made to the above description.

[0087] In the flat filter element 10.5, the inflow surface 44 of the inner filter medium body arrangement 14 is inclined relative to its outflow surface 40. Thus, the axial extent 32 changes along a transverse direction 78, which runs perpendicular to the folded edges 28 and the axial direction 46. The thickness of the inner filter medium body 18, which varies in the transverse direction 78, is caused by different pleat heights of the folds of the filter medium 24 arranged successively in the transverse direction 78.

[0088] The inflow surface 42 of the outer filter medium body arrangement 12 runs parallel to the two outflow surfaces 38, 40 extending in a common plane. The inflow surface 44 of the inner filter medium body 18 begins at one end (right in Figure 8) at the axial height of the inflow surface 42 of the outer filter medium body 16. Towards the other end, the inflow surface 44 of the inner filter medium body 18 protrudes increasingly further from the inflow surface 42 of the outer filter medium body 16. The distance between the inflow surfaces 42, 44 changes in the transverse direction 78 in accordance with the change in the axial extension 30 of the inner filter medium body 18.

[0089] Figures 9 and 10 show a flat filter element 10.6, which in many aspects corresponds to the flat filter element 10.4 of Figure 7. The differences are primarily explained below; otherwise, reference is made to the above description.

[0090] In the flat filter element 10.6, the recess 20 in the outer filter medium body assembly 12 is octagonal in shape. Accordingly, an outer contour of the inner filter medium body assembly 14 is also octagonal. Likewise, the gap 48 (see Figure 10) and the connecting means 50, or the inner seal 52 formed by the connecting means 50 (see Figure 9), are octagonal.

[0091] It is understood that—regardless of the ratio and course of the axial extensions 30, 32 of the two filter medium body assemblies 12, 14—other polygonal or rounded shapes, such as elliptical or circular shapes, could also be provided for the recess and the inner filter medium body assembly 18. The positioning of the inner filter medium body assembly 14 within the outer filter medium body assembly 12 is also fundamentally variable. The shape and position of the inner filter medium body assembly 14, as well as its thickness and axial alignment relative to the outer filter medium body assembly 12, depend in particular on the size and location of the interfering contours to be considered.

[0092] End edges of the filter medium bodies 16, 18 extending transversely to the folded edges 26, 28 and the inflow and outflow surfaces 38-44 can be sealed by glue beads 84. This is indicated in Figure 10 for the outer filter medium body 16 in the region of the recess 20. Likewise, end edges of the outer filter medium body 16 and the inner filter medium body 18 can be sealed by glue beads on their respective outer surfaces extending transversely to the folded edges 26, 28 (not shown in detail in Figure 10; see, for example, Figure 6 for the outer filter medium body 16).

[0093] Figures 11 and 12 show a flat filter element 10.7 that combines aspects of the flat filter element 10.2 of Figure 5 and the flat filter element 10.4 of Figure 7. The differences are primarily explained below; otherwise, reference is made to the above description.

[0094] In the flat filter element 10.7, an outer filter medium body arrangement 12 is formed with two outer filter medium bodies 16.1 and 16.2. The two outer filter medium bodies 16.1 and 16.2 are each L-shaped in the plane of the main extension of the flat filter element 10.7. An outer contour of the flat filter element 10.7, defined by the outer filter medium body arrangement 12, is rectangular. The lengths and widths of the legs of the two outer filter medium bodies 16.1, 16.2 are selected such that the two outer filter medium bodies 16.1, 16.2 enclose a recess 20, which is also rectangular in this exemplary embodiment. An inner filter medium body arrangement 14, which here is formed with a single inner filter medium body 18, is arranged in the recess 20.

[0095] The two outer filter medium bodies 16.1, 16.2 are each obtained by multiple folding of a flat filter medium 22. Here, for example, the same type of filter medium 22 is used for both outer filter medium bodies 16.1, 16.2, whereby the two filter medium bodies 16.1, 16.2 consist of separate pieces of the filter medium 22; however, it is also conceivable to use two different types of filter medium for the two outer filter medium bodies 16.1, 16.2. The inner filter medium body 18 is also obtained from a flat filter medium 24 by folding. The filter medium 24 can correspond to the filter medium 22 or differ from it. In any case, the inner filter medium body 18 consists of a piece of filter medium 24 which is separate from the pieces of filter medium 22 of the outer filter medium bodies 16.1, 16.2.

[0096] In the present embodiment, folded edges 26.1 and 26.2 of the two outer filter medium bodies 16.1, 16.2 extend parallel to one another. Folded edges 28 of the inner filter medium body 18 also run parallel to the folded edges 26.1, 26.2 of the outer filter medium bodies 16.1, 16.2. Alternatively, the folded edges of one or two of the filter medium bodies could extend at an angle to the folded edges of the other filter medium bodies, wherein the angle can be 90°, for example (not shown in detail).

[0097] The filter medium bodies 16.1, 16.2, 18 obtained by folding flat filter medium 22, 24 each have an axial extension 30.1, 30.2, 32 (measured in the axial direction 46, which corresponds to a main flow direction) which is greater than a thickness 34, 36 of the respective filter medium 22, 24. In the present case, the axial extension 30.1 of the first outer filter medium body 16.1 is greater than the axial extension 32 of the inner filter medium body 18. The axial extension 30.2 of the second outer filter medium body 16.2 is smaller than the axial extension 32 of the inner filter medium body 18 in this exemplary embodiment.

[0098] Outflow surfaces 38.1, 38.2 of the outer filter medium bodies 16.1, 16.2 and an outflow surface 40 of the inner filter medium body 18 run in a common plane here, compare Figure 11. Inflow planes 42.1, 42.2, 44 of the filter medium bodies 16.1, 16.2, 18 are offset from one another in the axial direction 46, compare Figure 12. Here, the inflow surface 42.1 of the first outer filter medium body 16.1 protrudes beyond the inflow surface 44 of the inner filter medium body 18; the inflow surface 44 of the inner filter medium body 18 protrudes beyond the inflow surface 42.2 of the second outer filter medium body 16.2.

[0099] The filter medium bodies 16.1, 16.2, and 18 in the flat filter element 10.7 are held together by a common connecting element 50, see Figure 11. The connecting element 50 fixes the inner filter medium body 18 to the two outer filter medium bodies 16.1, 16.2. The connecting element 50 forms an inner seal 52, which seals a gap 48 surrounding the inner filter medium body 18 (see Figure 12) from the adjacent outer filter medium bodies 16.1, 16.2.

[0100] In addition, the connecting means 50 secures the two outer filter medium bodies 16.1, 16.2 to each other at their boundary. The connecting means 50 forms an intermediate seal 86, which seals a gap 88 between the two outer filter medium bodies 16.1, 16.2. The intermediate seal 86 here has two sections that border the recess 20 at different locations.

[0101] Furthermore, an outer seal 54 surrounding the outer filter medium body assembly 12 is formed here as a component of the connecting means 50. Thus, in this exemplary embodiment, the inner seal 52, the intermediate seal 86, and the outer seal 54 are formed by the overall one-piece connecting means 50.

[0102] Figure 13 shows a pleated filter medium 22 or 24, with which the filter medium body of a flat filter element described above can be formed. The filter medium 22 / 24 is multi-layered. Two outer layers 90, 92 of filter material can be formed by filter paper and / or filter fleece. A layer 94 of adsorption material is arranged between the outer layers 90, 92. The adsorption material can contain activated carbon particles. The adsorption material serves to separate harmful gases from the air stream to be filtered. The outer layers 90, 92 serve, on the one hand, to filter out particles from the air stream. On the other hand, the outer layers 92, 94 serve to prevent particles of the adsorption material from escaping.

[0103] In summary, the invention relates to a flat filter element with multiple filter medium bodies. An inner filter medium body is accommodated in a recess that is circumferentially bounded by at least one outer filter medium body. The inner and outer filter medium bodies are formed with separate pieces of preferably pleated filter medium. The inner filter medium body is attached to the outer filter medium body(s). Preferably, a connecting means serving for attachment simultaneously seals the inner and outer filter medium bodies from one another. List of Reference Symbols

[0104] Flat filter element 10.1; 10.2; 10.3; 10.4; 10.5; 10.6; 10.7 outer filter medium body assembly 12 inner filter medium body assembly 14 outer filter medium body 16; 16.1, 16.2 inner filter medium body 18

[0105] Recess 20

[0106] Filter medium 22 of the outer filter medium body assembly 12

[0107] Filter medium 24 of the inner filter medium body assembly 14

[0108] Folded edges 26 of the outer filter medium body assembly 12

[0109] Folded edges 28 of the inner filter medium body assembly 14

[0110] Axial extension 30; 30.1 , 30.2 of the outer filter medium body assembly 12

[0111] Axial extension 32 of the inner filter medium body assembly 14

[0112] Thickness 34 of the filter medium 22

[0113] Thickness 36 of the filter medium 24

[0114] Outflow surface 38; 38.1 , 38.2 of the outer filter medium body assembly 12

[0115] Outflow surface 40 of the inner filter medium body assembly 14

[0116] Inflow surface 42; 42.1 , 42.2 of the outer filter medium body assembly 12

[0117] Inflow surface 44 of the inner filter medium body arrangement 14

[0118] Axial direction 46

[0119] Gap 48

[0120] Lanyard 50

[0121] Inner seal 52

[0122] Outer seal 54

[0123] Housing 56 first housing part 58 second housing part 60

[0124] Air filter 62.1 ; 62.2

[0125] Raw air intake 64

[0126] Support struts 66

[0127] Invagination 68

[0128] Housing wall 70

[0129] Interference contour 72

[0130] Clean air outlet 74

[0131] Support projections 76

[0132] Transverse direction 78

[0133] Indentation 80 further interference contour 82 glue bead 84

[0134] Intermediate seal 86

[0135] Gap 88 outer layers 90, 92 of filter material

[0136] Layer 94 of adsorption material

Claims

Claims 1 . Flat filter element (10.1 - 10.7), in particular an air filter element, preferably for an intake air filter of an internal combustion engine or fuel cell, comprising an outer filter medium body arrangement (12) with at least one outer filter medium body (16; 16.1, 16.2) and an inner filter medium body arrangement (14) with at least one inner filter medium body (18), wherein the two filter medium body arrangements (12, 14) can be flowed through in an axial direction (46), wherein the inner filter medium body arrangement (14) is formed separately from the outer filter medium body arrangement (12), wherein the inner filter medium body arrangement (14) is inserted into a recess (20) of the outer filter medium body arrangement (12), wherein the outer filter medium body arrangement (12) and the inner filter medium body arrangement (14) are connected to one another via a connecting means (50), and wherein the outer filter medium body arrangement (12) has an axial extension (30; 30.1, 30.2) along the circumference of the recess (20) which corresponds to a multiple of a thickness (34) of a filter medium (22) from which the at least one outer Filter medium body (16; 16.1, 16.2) is formed.

2. Flat filter element (10.1 - 10.7) according to claim 1, wherein the outer filter medium body arrangement (12) comprises exactly one outer filter medium body (16) or several, preferably exactly two, outer filter medium bodies (16.1, 16.2).

3. Flat filter element (10.1) according to claim 1 or 2, wherein the inner filter medium body arrangement (14) and the outer filter medium body arrangement (12) have the same axial extensions (30; 30.1, 30.2).

4. Flat filter element (10.2-10.7) according to claim 1 or 2, wherein the inner filter medium body arrangement (14) and the outer filter medium body arrangement (12) have at least partially different axial extensions (30; 30.1, 30.2).

5. Flat filter element (10.1 - 10.7) according to one of the preceding claims, wherein outflow surfaces (38; 38.1, 38.2, 40) and / or inflow surfaces of the inner filter medium body arrangement (14) and the outer filter medium body arrangement (12) lie in a common plane.

6. Flat filter element (10.2-10.7) according to one of the preceding claims, wherein inflow surfaces (42; 42.1, 42.2, 44) and / or outflow surfaces of the inner filter medium body Arrangement (14) and the outer filter medium body arrangement (12) are offset from one another in the axial direction (46), preferably extending in planes parallel to one another.

7. Flat filter element (10.2-10.7) according to one of the preceding claims, wherein the at least one inner filter medium body (18) protrudes at least partially in the axial direction (46) on the upstream and / or downstream side beyond the at least one outer filter medium body (16; 16.2).

8. Flat filter element (10.2-10.7) according to one of the preceding claims, wherein the at least one inner filter medium body (18) is set back at least partially in the axial direction (46) behind the at least one outer filter medium body (16; 16.1) on the upstream and / or downstream side.

9. Flat filter element (10.1 -10.7) according to one of the preceding claims, wherein the Connecting means (50) extends over the entire circumference of the recess (20).

10. Flat filter element (10.1 -10.7) according to one of the preceding claims, wherein the Connecting means (50) forms a circumferential inner seal (52), preferably wherein the connecting means (50) consists of a plastic, in particular polyurethane, particularly preferably wherein the connecting means (50) is formed, in particular foamed, onto the inner filter medium body arrangement (14) and the outer filter medium body arrangement (12).

11. Flat filter element (10.1 - 10.7) according to one of the preceding claims, wherein a circumferential outer seal (54) is arranged on an outer circumference of the outer filter medium body arrangement (12), preferably wherein the outer seal (54) consists of a plastic, in particular polyurethane, particularly preferably wherein the outer seal (54) is molded, in particular foamed, onto the outer filter medium body arrangement (12).

12. Flat filter element (10.1 - 10.7) according to claim 10 and claim 11, wherein the inner seal (52) and the outer seal (54) are arranged on the same side of the flat filter element (10.1 - 10.7), preferably on the downstream side.

13. Flat filter element (10.1 - 10.7) according to one of the preceding claims, wherein a gap (48), in particular a continuous circumferential gap (48), is formed between the inner filter medium body arrangement (14) and the outer filter medium body arrangement (12).

14. Flat filter element (10.1 - 10.7) according to one of the preceding claims, wherein the at least one inner filter medium body (18) and / or the at least one outer filter medium body (16; 16.1, 16.2) comprise folded filter medium (22, 24).

15. Flat filter element (10.1 - 10.7) according to claim 14, wherein folded edges (26; 26.1, 26.2, 28) of the at least one inner filter medium body (18) and of the at least one outer filter medium body (16; 16.1, 16.2) extend parallel to one another or at an angle, in particular at an angle of 90°, to one another.

16. Flat filter element (10.3; 10.5) according to one of the preceding claims, wherein an axial extension (30, 32) of the inner filter medium body arrangement (12) and / or the outer filter medium body arrangement (14) changes along a transverse direction (78).

17. Flat filter element (10.1 - 10.7) according to one of the preceding claims, wherein a filter medium (22, 24) of the inner filter medium body arrangement (14) and / or the outer filter medium body arrangement (12) is a filter paper or filter fleece, in particular a multi-layer filter paper or filter fleece.

18. Flat filter element (10.1 - 10.7) according to one of the preceding claims, wherein a filter medium (22, 24) of the inner filter medium body arrangement (14) and / or the outer filter medium body arrangement (12) contains an adsorbent, in particular activated carbon.

19. Air filter (62.1; 62.2) comprising a flat filter element (10.1 - 10.7) according to one of the preceding claims and a, preferably multi-part, housing (56) in which the flat filter element (10.1 - 10.7) can be arranged.

20. Air filter (62.1; 62.2) according to claim 19, wherein a first housing part (58) of the housing (56) has at least one support strut (66) which, in the assembled state, rests against the connecting means (50), in particular on the upstream side, preferably wherein the support strut (66) engages in a gap (48) between the inner filter medium body arrangement (14) and the outer filter medium body arrangement (12).

21. Air filter (62.1; 62.2) according to claim 19 or 20, wherein a second housing part (60) of the housing (56) has at least one supporting projection (76) which, in the assembled state, bears against the connecting means (50), in particular on the downstream side.

22. Air filter (62.1; 62.2) according to claim 20 and claim 21, wherein the connecting means (50) is clamped in the assembled state between the at least one support strut (66) and the at least one support projection (76).

23. Air filter (62.1; 62.2) according to one of claims 19 to 22, wherein in the assembled state an outer seal (54) running around an outer circumference of the outer filter medium body arrangement (12) seals two housing parts (68, 60) of the housing (56) against one another.

24. Air filter (62.1; 62.2) according to one of claims 19 to 23, wherein the housing (56) has an indentation (68) which extends from a housing wall (70) to the inner filter medium body arrangement (14).

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