FILTER ELEMENT AND FILTER SYSTEM

Description

Technical field

[0001] The invention relates to a filter system, in particular for air, especially the intake air of an internal combustion engine, particularly of a motor vehicle. The filter system can be used for air filtration for fuel cells, in particular as a cathode air filter. Furthermore, the filter system can additionally be designed for the adsorption of pollutant gases. State of the art

[0002] From EP 3 003 533 A2, a filter system is known in which a conical secondary filter element is inserted into the clean-side interior of a cylindrical primary filter element. Annular end plates are arranged on both end faces of the filter element, so that both sides of the filter element are open. The primary filter element seals axially against a housing cover. The end face of the secondary filter element facing the housing cover is closed and rests against the housing cover.

[0003] A filter system according to the preamble of claim 1 is known from DE 10 2017 005797 A1. Disclosure of the invention

[0004] One object of the invention is to provide a filter system that allows for material and weight savings in the housing.

[0005] The aforementioned problem is solved according to one aspect of the invention with a filter system according to claim 1. The filter system has a housing with an inlet and an outlet for a fluid, wherein a first filter element, designed as a hollow body – in particular hollow cylindrical – with a filter medium is arranged in the housing, and a second filter element is arranged in an interior of the first filter element, wherein the first filter element and the second filter element are arranged coaxially and concentrically to each other about a longitudinal axis, wherein the first filter element has a first end disk arranged on an outlet-side end face and a second end disk arranged on the opposite end face, each of which end disks has a central opening and extends substantially in an annular shape over the respective end face of the filter medium.wherein the second filter element has a first end face on the outlet side and a second end face opposite the outlet-side end face, which is fluid-tightly sealed by a cover, wherein the opening in the second end disk of the first filter element is fluid-tightly sealed by the cover, and wherein a sealing interface is arranged between the second end face of the first filter element and the second end face of the second filter element. The two filter elements seal directly against each other via the sealing interface.

[0006] Favorable embodiments and advantages of the invention will become apparent from the further claims, the description and the drawing.

[0007] A filter system is proposed comprising a housing with an inlet and an outlet for a fluid. A first filter element, designed as a hollow body and containing a filter medium, is arranged around a longitudinal axis within the housing, and a second filter element is arranged within an interior space of the first filter element. The two filter elements are arranged coaxially and concentrically around a longitudinal axis of the first filter element. The longitudinal axis of the filter element can coincide with a longitudinal axis of the filter housing. Alternatively, the filter elements can be arranged eccentrically within the filter housing with respect to a housing axis. The first filter element has a first end disk located on an outlet-side end face and a second end disk located on the opposite end face. These end disks each have a central opening and extend essentially in an annular shape over their respective end faces containing the filter medium.The second filter element has a first end face on the outlet side and a second end face opposite the outlet-side end face, which is fluid-tightly sealed by a cover. The opening in the second end plate is fluid-tightly sealed by the cover, with a sealing interface arranged between the second end face of the first filter element and the second end face of the second filter element.

[0008] The sealing interface comprises at least one sealing surface on one of the filter elements and at least one sealing element on the other filter element. The sealing element can be formed from a foamed polymer that is foamed onto one of the filter elements or from an injection-molded thermoplastic. The foamed polymer can, in particular, be a polyurethane. The same material can form both the sealing element and the end plate. Alternatively, the sealing element can be a two-component (2K) component in which a thermoplastic elastomer is injection-molded onto a thermoplastic carrier present on one of the filter elements. The carrier can be made of a polymer, in particular PP or PA. The sealing element can also be, in particular, an extruded sealing element that is attached to the carrier.

[0009] The sealing interface is located directly between the two filter elements. Complex additional components can be avoided. The first filter element can also be referred to as the main element, and the second filter element as the secondary or safety element. Preferably, the filter medium of the first filter element is a zigzag-folded filter medium designed as a hollow body. The hollow body can be cylindrical or conical. Various base shapes are conceivable; preferably, the base shape is circular or oval. In the case of a circular-cylindrical filter element, the end discs are correspondingly annular. The filter medium is preferably arranged around a support tube. The end discs are preferably made of a foamed polymer, in particular a polyurethane.The housing can advantageously be designed coaxially around a longitudinal axis that coincides with the longitudinal axis of the filter element, and in particular, the housing can have the outlet as a nozzle arranged coaxially to the longitudinal axis. The second filter element has its end face, closed by the cover, on the side of the housing opposite the outlet. The filter medium of the second filter element is preferably a single-layer or multi-layer wound filter medium, preferably arranged on a support tube. Alternatively, the filter medium of the second filter element can be a bellows formed into a hollow body. The sealing interface is thus located on the side of the housing opposite the outlet. The cover can be formed integrally with the support tube of the second filter element and can be made of a hard plastic, in particular a polymer such as PP or PA.In particular, if the second filter medium is designed as a bellows, the cover can also be made of a soft plastic, especially a foamed polyurethane, and advantageously simultaneously form the end-face seal of the folds.

[0010] The filter system is, for example, an air filter system, in particular an air filter system for an internal combustion engine, preferably an air filter system for an internal combustion engine or a fuel cell of a motor vehicle.

[0011] According to a favorable embodiment, the sealing interface can comprise at least one sealing surface on a support tube of the first filter element opposite a clean-side outlet and at least one sealing element on the second filter element, which seals against the sealing surface in an axial and / or radial direction.

[0012] Preferably, the sealing element can be arranged directly on the cover or at a distance from the cover on the second filter element. Furthermore, the first filter element can be supported on its outer side by the housing.

[0013] According to a favorable embodiment, the sealing interface can comprise a sealing element, in particular a sealing ring, arranged on a circumferential projection on the cover, which extends axially from an outer end face of the cover, the sealing element sealing radially against a support tube of the first filter element. The sealing element can be formed from a foamed polymer foamed onto or around the projection or from an injection-molded thermoplastic. The foamed polymer can, in particular, be a polyurethane. The sealing element can be a two-component (2K) component in which a thermoplastic is injection-molded onto the projection.

[0014] According to a favorable embodiment, the sealing interface can comprise a sealing element arranged on a circumferential edge of the cover and sealing radially against a support tube of the first filter element. Advantageously, the sealing element can be a molded body made of a foamed polymer, foamed onto the edge and sealing with its outer surface against the support tube of the first filter element, or a thermoplastic that is injection-molded onto the edge.

[0015] In a preferred embodiment, the sealing interface at the end face of the second filter element, particularly at the cover, can comprise a sealing element, especially a sealing ring or a sealing projection, which seals axially against a radially inwardly projecting edge of the support tube of the first filter element. A circumferential ring can be arranged on the cover, embedded in the sealing element, thus enabling a stable connection between the sealing element and the second filter element. The sealing element is preferably a foamed polymer, particularly a polyurethane, or a thermoplastic. Advantageously, the end plate of the first filter element can at least partially cover the inwardly projecting edge. This allows for improved sealing between the central tube and the end plate, as well as stable support of the sealing surface.The radially inward-facing edge of the support tube of the first or outer filter element can have a groove into which the sealing element, in particular the sealing projection, engages. The sealing element can seal axially against the groove base and / or against an axial end face of a projection delimiting the groove.

[0016] According to a favorable embodiment, the sealing interface can comprise a region of the second end disk of the first filter element, which is axially opposite a clean-side outlet, and at least one sealing surface on the second filter element. Advantageously, the end disk can be shaped as desired during manufacturing using a suitable mold. In some embodiments, the end disk can perform its sealing function against the second filter element with, or alternatively without, support from the housing.

[0017] Advantageously, the second end disc of the first filter element can project radially inwards beyond the filter medium. The support tube can also be inclined inwards at its axial end and / or provided with an inwardly facing rim. This supports and stabilizes the inwardly projecting end disc in this area. For example, if the sealing element is part of the first filter element, the support tube can be designed to stiffen a soft sealing element or to attach the sealing element. If the second filter element has or carries the sealing element, the support tube can be designed as a counter-contour to create a tight seal between the two filter elements.

[0018] In a preferred embodiment, the area can be located on an inner edge of the second end disk of the first filter element, sealing against a sealing surface on a radially outer circumferential surface of a circumferential projection arranged on the cover, which extends axially away from the cover. In particular, an axially directed collar on the second housing part can engage in a groove of the second end disk. Advantageously, the end disk can be supported by the housing, thus ensuring reliable contact between the end disk, which forms the sealing element, and the sealing surface of the second filter element.

[0019] According to a favorable embodiment, the area of ​​the second end disk of the first filter element can seal radially against a sealing surface of a circumferential projection arranged on an inner side of the cover, which extends axially away from the cover, the projection being able to engage in a groove in the end disk. In particular, an inner edge of the second end disk of the first filter element can be radially supported by a web on the second housing part that projects axially inwards. This ensures stable retention of the end disk, which forms the sealing element of the sealing interface.

[0020] According to a preferred embodiment, the area can be located on an inner edge of the second end disk of the first filter element, sealing against a sealing surface on a radially outer circumferential surface of a circumferential projection arranged on the cover, which extends axially away from the cover. The end disk can have an axial projection in the area that contacts or touches the sealing surface of the second filter element to provide a large sealing area.

[0021] According to a favorable embodiment, the area can be arranged on an axially inwardly projecting end face of a radial projection of the second end disk of the first filter element, which surrounds within the cross-section of the filter medium and seals against a sealing surface on an end face of the cover. In particular, the support tube can have a radially inwardly projecting circumferential rim that can be embedded in the radial projection, thus providing stable support for the sealing interface. According to a favorable embodiment, an end face of the second housing part can be convexly curved. This ensures that only suitable filter elements are inserted into the housing.

[0022] In a favorable embodiment, the end face of the second housing part can have an opening that extends at least partially across the end face of the second filter element. When the second filter element is installed, the opening is covered by the end face cover of the filter element. Sealing is achieved via at least partially concentric sealing surfaces on at least two of the components: the first filter element, the second filter element, and the second housing part. The opening ensures that only suitable filter elements are inserted into the housing. A visual inspection is possible to verify that a suitable second filter element is installed without opening the housing. Material savings in the housing result in weight reduction.

[0023] A filter element is proposed for the filter system according to the invention, comprising a filter medium, in particular folded in a zigzag pattern and formed into a hollow body, a first end disk arranged on one end face, and a second end disk arranged on the opposite end face, wherein both end disks each have a central opening and extend essentially in an annular shape over the end faces – in the case of a folded filter medium, over the folds – of the filter medium, wherein a sealing surface or a region of a sealing element of a sealing interface is arranged on the end face which, in the installed state, is intended to be opposite a clean air outlet. The filter element is preferably cylindrical, in particular circular cylindrical, but can also be conical.

[0024] Advantageously, the filter element can be a main component in the filter system. The main component can be fluid-tightly connected to the second filter element, preferably a secondary component, via the sealing interface. For example, the end plate can be made of a foamed polymer, particularly polyurethane. The filter element's design is compact and eliminates the need for additional sealing components. Installation in the filter system can be simplified.

[0025] In a preferred embodiment, the filter medium can be arranged around a support tube, the support tube having the sealing surface. During manufacturing, the support tube can be designed to form the sealing surface as a counter-contour to a sealing element. Alternatively, the support tube can be designed to accommodate a sealing element and / or to stiffen a soft sealing element. The support tube can have a radially inwardly extending rim on which the sealing surface is located. In particular, an axially inwardly directed section of the rim forms the sealing surface.

[0026] According to a favorable embodiment, the end plate can have the sealing element-side area of ​​the sealing interface on its end face, which, in the installed state, is intended to face a clean air outlet. The end plate can advantageously extend radially inwards in an annular shape over the filter medium. This annular, radially inward area can form the sealing element of the sealing interface. In embodiments, this area has a groove that interacts with the sealing surface of the counterpart of the sealing interface.

[0027] In this embodiment of the filter system, weight can be advantageously saved because the end plate of the outer filter element does not need to be closed. The opening in the base of the outer filter element allows for savings in end plate material.

[0028] A further filter element is proposed for the filter system according to the invention, comprising a filter medium arranged in a single or multiple layer on a support tube, a first circumferential nozzle arranged on one end face and extending in the axial direction, and a second cover arranged on the opposite end face, wherein the cover has at least one sealing surface or at least one sealing element which, in the installed state, forms a sealing interface with another filter element. The filter medium can be wound around the support tube or folded in a zigzag pattern and formed into a hollow body enclosing the support tube.

[0029] Advantageously, the filter element can be a secondary element in the filter system. The secondary element can be fluid-tightly connected to the first filter element, preferably a main element, via the sealing interface. The filter element is preferably cylindrical, in particular circular cylindrical, but can also be conical.

[0030] Alternatively or additionally, the filter element can be designed for pollutant gas adsorption and be fluid-tightly connected to a particle filter element via the sealing interface. For pollutant gas adsorption, the filter element incorporates a suitably appropriate filter medium, in particular a filter medium containing activated carbon.

[0031] In a preferred embodiment, a circumferential projection can be arranged on the cover, extending axially away from the cover, and the circumferential projection can carry a sealing element. Advantageously, the projection can be embedded in the sealing element. For example, the sealing element can be made of a foamed polymer, in particular a polyurethane, or of a thermoplastic. It is also possible for the projection itself to consist of a foamed polymer and to form the sealing element, particularly if the second filter element is designed as a bellows with foamed end plates. The projection can then be easily manufactured as a single piece with the end plate.

[0032] In a favorable embodiment, a sealing element can be arranged at an edge of the cover or the support tube. Advantageously, a foamed polymer, in particular a polyurethane, or a thermoplastic can be arranged at the edge.

[0033] In a favorable embodiment, a circumferential projection extending axially outwards can be arranged on the cover as a sealing surface of the sealing interface. The projection can be designed in a suitable manner to form a sealing surface or sealing interface. Brief description of the drawings

[0034] Further advantages become apparent from the following description of the drawings. The drawings illustrate exemplary embodiments of the invention. The drawings, the description, and the claims contain numerous features in combination. A person skilled in the art will expediently consider the features individually and combine them into meaningful further combinations. The following are shown as examples: Fig. 1 a filter system according to an embodiment of the invention in a sectional view; Fig. 2 a section of a filter system according to an embodiment of the invention in a sectional view with a radial seal between the first and second filter element; Fig. 3 a section of a filter system according to a further embodiment of the invention in a sectional view with a radial seal between the first and second filter element; Fig. 4 a section of the filter system in Figure 1Fig. 5 shows a section of a filter system according to a further embodiment of the invention in a sectional view with an axial seal between the first and second filter elements; Fig. 6 shows a section of a filter system according to a further embodiment of the invention in a sectional view with a radial seal between a second filter element and an end plate of a first filter element; Fig. 7 shows a section of a filter system according to a further embodiment of the invention in a sectional view with a radial seal between the first and second filter elements; Fig. 8 shows a section of a filter system according to a further embodiment of the invention in a sectional view with an axial seal between the first and second filter elements.9 a filter system according to a further embodiment in a sectional view and Fig. 10 a section from the embodiment according to . Figure 9 in a sectional view. Embodiments of the invention

[0035] In the figures, identical or similar components are numbered with the same reference symbols. The figures merely show examples and are not to be understood as limiting.

[0036] In the embodiments in Figures 1 to 4 A sealing interface 80 has a sealing element 60, 62, 64 on the cover 50 of the second filter element 40 and a sealing surface 25 on a support tube 24 of the first filter element 10.

[0037] Figure 1 and 4 show a filter system 100 according to a first embodiment of the invention, wherein Figure 1 a longitudinal section view through the filter system 100 and Figure 4 an excerpt from the filter system 100 in Figure 1The filter system 100 is, for example, an air filter system, in particular an air filter system for an internal combustion engine, preferably an air filter system for an internal combustion engine of a motor vehicle or a cathode air filter of a fuel cell of a motor vehicle.

[0038] The filter system 100 comprises a housing 102 with an inlet 108, which may, for example, be arranged tangentially to the housing 102 and is concealed by the housing 102 in the figure, and a nozzle-shaped outlet 110 for a fluid, arranged coaxially to a longitudinal axis 70. The inlet 108 and outlet 110 are, for example, arranged at opposite axial ends of the housing 102. The housing 102 comprises a first housing part 104, for example, a housing pot, and a second housing part 106, for example, a housing cover. The housing pot may be fixedly mounted, and the housing cover may be removed from it to access the interior of the housing.

[0039] In the housing 102, a first, hollow cylindrical filter element 10 is arranged coaxially to the longitudinal axis 70. In an interior space 30 of the first filter element 10, a second filter element 40 is arranged coaxially to the longitudinal axis 70 and concentrically to the first filter element 10.

[0040] In the illustrated embodiment, the longitudinal axis of the housing 102 coincides with the longitudinal axis of the first filter element 10 and the second filter element 40, so that only a single common longitudinal axis 70 is referenced here. However, embodiments are also conceivable in which the first filter element 10 and the second filter element 40 are arranged concentrically to each other around a longitudinal axis that differs from a longitudinal axis of the filter housing. In these cases, the filter elements would be arranged eccentrically in the filter housing.

[0041] The first filter element 10, also referred to as the main element 10, comprises a filter medium 11 arranged on a support tube 24. The first filter element 10 has a first end disk 14 located on an outlet-side end face 12 and a second end disk 18 located on the opposite end face 16. Both end disks 14, 18 each have an opening 21, 22 and extend essentially in an annular shape over the respective end face 14, 16 of the filter medium 11. The filter medium 11 is, for example, folded in a zigzag pattern. In the illustrated embodiment, the openings 21, 22 are arranged coaxially with the longitudinal axis 70.

[0042] The second filter element 40, also referred to as the secondary element 40, has a filter medium 47 arranged on a support tube 48. For example, the filter medium 47 is applied to the support tube 48 in a single layer or in multiple layers. The second filter element 40 has a first end face 42 on the outlet side and a second end face 46 opposite the outlet-side end face 42. The first end face 42 is open and has a nozzle 44 which is connected to the first housing part 104 at the nozzle-shaped outlet 110, for example, by being screwed to it via an external thread (not specified) on the nozzle 44 of the second filter element 40.

[0043] The second filter element 40 can serve as a safety element when replacing the main filter element 10, or it can be designed as a pollutant gas filter element and adsorb pollutant gases. For this purpose, the filter medium 47 can contain activated carbon.

[0044] The flow direction of the fluid between inlet 108 and outlet 110 through both filter elements 10, 40 is indicated by broad arrows. The fluid flows through the filter elements 10, 40 in a radial direction 74 from the outside to the inside. The first filter element 10 can be pulled out of the housing 102, while the second filter element 40 remains connected to the second housing part 104 and protects the clean-side outlet 110 from unfiltered fluid.

[0045] The second filter element 40 is fluid-tightly sealed at its second end face 46, opposite the clean-side outlet 110, by means of a cover 50. The second filter element 40 seals the opening 22 in the second end plate 18 fluid-tightly by means of the cover 50. For fluid-tight sealing of the opening 22, a sealing interface 80 is arranged between the second end face 16 of the first filter element 10 and the second end face 46 of the second filter element 40. The cover 50 and the support tube 48 of the second filter element 40 are preferably formed in one piece.

[0046] The sealing interface 80 comprises, on the end faces of the filter elements 10, 40 opposite the clean-side outlet 110, at least one sealing surface on one of the filter elements 10, 40 and at least one sealing element on the other of the filter elements 10, 40. The second filter element 40 seals the opening 22 in the end plate 18 of the first filter element 10 in a fluid-tight manner, without the need for additional components. Depending on the design, the sealing element can seal in the axial direction 72 or in the radial direction 74.

[0047] In the Figure 1 depicted design, which in Figure 4As shown enlarged, the sealing interface 80 is provided with an annular sealing element 64 on the cover 50, as well as a sealing surface 25 on the support tube 24 of the first filter element 10. The cover 50 and the support tube 48 of the second filter element 40 are preferably formed in one piece. The sealing element 64 is arranged on the end face 46 of the second filter element 40 on a circumferential projection 54 of the cover 50 that extends axially 72 outwards. The projection 54 is embedded in the sealing element 64. The sealing element 64 forms a circumferential ring on the cover 50 and seals axially at the sealing surface 25 against an edge 26 of the support tube 24 that extends radially 74 inwards. The edge 26 of the support tube 24 rests on the end disk 18.

[0048] The second housing part 106 has a receptacle for the first filter element 10, such that the outer surface of the first filter element 10, in the area of ​​its second end disk 18, rests against a ring 116 surrounding the filter element 10. The first filter element 10 is supported against the base of the second housing part 106 by means of support lugs not specified in detail.

[0049] In the illustrated embodiment, the second housing part 106 is curved inwards in the area of ​​the opening 22 of the end disk 18, with an indentation in the end face 112. The indentation projects into the opening 22.

[0050] Since the basic structure of the filter elements 10, 40 and the housing 102 is largely the same in the various embodiments, to avoid unnecessary repetition, only essential differences in the sealing interface 80 will be discussed in the further embodiments.

[0051] Figure 2shows a section of a filter system 100 according to a further embodiment of the invention in a sectional view with a sealing interface 80 with a radial seal between the first and second filter element 10, 40.

[0052] The sealing interface 80 comprises a sealing element 60 designed as a sealing ring, which is arranged on a circumferential projection 52. This projection extends outwards from the cover 50 in an axial direction 72 on an outer end face and is embedded in the sealing element 60. The sealing element 60 seals radially 74 against the sealing surface 25 on the support tube 24 of the first filter element 10. The support tube 24 has a cross-sectional constriction in the area of ​​the sealing surface 25 of the first filter element 10.

[0053] The first filter element 10 is received in a recess in the second housing part 106 and is radially surrounded on the outside by a ring 116. As before, the bottom of the second housing part 106 has a recess in the end face 112 in the area of ​​the opening 22 of the end disk 18 of the first filter element 10.

[0054] Figure 3 shows a section of a filter system 100 according to a further embodiment of the invention in a sectional view with a sealing interface 80 with a radial seal between the first and second filter element 10, 40.

[0055] The sealing interface 80 comprises a sealing element 62, which is arranged on an edge 51 of the cover 50 and seals in the radial direction 74 against a support tube 24 of the first filter element 10. The sealing element 62 has an L-shaped cross-section, with one leg extending axially 72 and one leg extending radially 74 inwards. The sealing element 62 can be injection-molded, or the edge 51 can be encased with a foamed polymer.

[0056] The support tube 24 has a cross-sectional narrowing in the area of ​​the sealing surface 25 of the first filter element 10.

[0057] The first filter element 10 is received in a recess in the second housing part 106 and is radially surrounded on the outside by a ring 116. As before, the bottom of the second housing part 106 has a recess in the end face 112 in the area of ​​the opening 22 of the end disk 18 of the first filter element 10.

[0058] In the embodiments in Figures 5 to 8 The sealing interface 80 has a region 15 of the second end disk 18 of the first filter element 10 as a sealing element and a sealing surface 45 on the second filter element 40.

[0059] Figure 5 shows a section of a filter system 100 according to a further embodiment of the invention in a sectional view with a radial seal between the first and second filter element 10, 40.

[0060] The area 15 is located on an inner edge of the second end disk 18 of the first filter element 10 and seals against a sealing surface 45 on a radially outer circumferential surface 74 of a circumferential projection 52 arranged on the cover 50, which extends axially 72 away from the cover 50. An axially 72-pointing web 114 engages in a groove 17 of the second end disk 18 on the second housing part 106. This supports the end disk 18 through the second housing part 106 of the housing 102. As a result, an outer ring 116 (Figures 2, 3, 4) arranged radially to the first filter element 10 for receiving the first filter element 10 in the second housing part 106 can be omitted.

[0061] In this embodiment, the second housing part 106 in the area of ​​the opening 22 in the second end disk 18 of the first filter element 10 is not curved, but open, so that the cover 50 is visible from the outside.

[0062] Figure 6 shows a section of a filter system 100 according to a further embodiment of the invention in a sectional view with a radial seal between the first and second filter element 10, 40.

[0063] The area 15 of the second end disk 18 of the first filter element 10 seals against a sealing surface 45 of a circumferential projection 56 arranged on an inner side of the cover 50 in the radial direction 74. The projection 56 extends axially 72 away from the cover 50 and is located at the outer edge of the cover 50. The end disk 18 extends with a radial overhang 20 beyond the edge region of the cover 50. The projection 56 engages in a groove 19 in the radial overhang 20 of the end disk 18. The inner circumference of the second end disk 18 of the first filter element 10 is supported in the radial direction 74 by a web 118 projecting inwards in the axial direction 72 on the second housing part 106 and secured in the radial direction 74 between the web 118 and the ring 116 in the second housing part 106.

[0064] In this embodiment as well, the second housing part 106 in the area of ​​the opening 22 in the second end disk 18 of the first filter element 10 is not curved, but open, so that the cover 50 is visible from the outside.

[0065] Figure 7 Figure 1 shows a section of a filter system 100 according to a further embodiment of the invention in a sectional view with a radial seal between the first and second filter elements 10, 40. The sealing interface 80 has a region 15 on the second end disk 18 of the first filter element 10, which corresponds to a clean-side outlet 110 ( Figure 1 ) opposite, and comprises at least one sealing surface 45 on the second filter element 40, on which the area 15 of the second end disk 18 of the first filter element 10 is in sealing contact.

[0066] The second end disk 18 of the first filter element 10 protrudes with a radial overhang 20 in a radial direction 74 inwards over the filter medium 11.

[0067] The area 15 is arranged on an inner edge of the second end disk 18 of the first filter element 10, which seals against a sealing surface 45 on a radially 74 outer circumferential surface of a circumferential projection 52 arranged on the cover 50, which extends in axial direction 72 outwards from the cover 50.

[0068] In this embodiment, the base of the second housing part 106 is convex, with a recess in the end face 112 projecting into the opening 22. The filter element 10 is received in a recess on the second housing part 106 and surrounded in the area of ​​its second end disk 18 by a supporting ring 116.

[0069] Figure 8shows a section of a filter system 100 according to a further embodiment of the invention in a sectional view with an axial seal between the first and second filter element 10, 40.

[0070] The area 15 is arranged on an axially inwardly projecting end face 58 of a radial projection 20 of the second end disk 18 of the first filter element 10, which surrounds within the cross-section of the filter medium 11 and seals against a sealing surface 45 on an end face of the cover 50. The support tube 24 has a radially inwardly projecting rim 23, which is embedded in the radial projection 20 of the second end disk 18 and thereby reinforces it. The second end disk 18 can axially support the sealing interface 80 in this area.

[0071] In Figure 9Figure 1 shows a further embodiment of a filter system 100, wherein the inner filter element 40 comprises a filter medium 47 in the form of a bellows, which is arranged around a support tube 48. The open folds are each closed at the end faces by means of an end plate 41, 49, to prevent airflow. The end plates 41, 49 are preferably made of an elastic material, in particular polyurethane foam. The upper end plate 49 is an open, annular end plate and has a circumferential sealing bead that seals against the nozzle 110. The lower end plate 41 is also annular and encloses the cover 50 of the support tube 48. The support tube 48 and the cover 50 are embedded section by section in the material of the end plate 41.Alternatively, the end disc 41 can be disc-shaped and cover the cavity enclosed by the filter element 40 at the front, so that the cover 50 can be omitted as part of the support tube 48.

[0072] In Figure 10 is an excerpt from the in Figure 9The illustrated filter system is shown in the area of ​​the sealing interface 80 of the bottom end discs 18, 41. The two filter elements 10, 40 are axially sealed against each other. The support tube 24 has an annular rim 27 extending radially 74 inwards, which is partially embedded in the material of the end disc 18. Radially inwards, the annular rim 27 has a groove 29, which is bounded radially outwards by an annular projection 59. This groove 29 serves to receive an axially directed annular sealing projection 43 on the lower end disc 41 of the inner filter element 40. The annular projection 59 of the rim 27 rests axially against the flat axial end face of the end disc 41 of the inner filter element 40. This configuration ensures a reliable axial seal between the two filter elements 10, 40.The lower end disc 41 of the inner filter element 40 simultaneously forms the seal of the pleats and the interface to the outer filter element 10; additional sealing elements are not required.

[0073] The inner filter element 40 can advantageously be a filter element for the adsorption of harmful gases. For this purpose, the filter medium is designed to be suitable for the adsorption of harmful gases. Preferably, the filter medium contains activated carbon.

[0074] Of course, other sealing configurations are also possible for sealing two filter elements 10, 40 designed as bellows. For example, a radially outer section of the lower end disk 41 of the inner filter element 40 can be similar to the embodiment shown in Figure 2 or Figure 3 to form a radial seal against an axially extending edge of the support tube 24 of the outer filter element 10.

Claims

1. A filter system (100) with a housing (102) with an inlet (108) and an outlet (110) for a fluid, wherein a first filter element (10) designed as a hollow body with a filter medium (11) is disposed in the housing (102) and a second filter element (40) disposed in an interior space (30) of the first filter element (10), wherein the first filter element (10) and the second filter element (40) are disposed coaxially and concentrically to each other around a longitudinal axis (70), wherein the first filter element (10) features a first end plate (14) disposed on an outlet-sided front face (12) and a second end plate (18) disposed on the opposite front face (16), which end plates (14, 18) each feature a central opening (21, 22) and extend substantially annularly over the respective front face (14, 16) of the filter medium (11), wherein the second filter element (40) features an outlet-sided first front face (42) and a second end face (46) opposite the outlet-sided front face (42), which is sealed in a fluid-tight manner with a cover (50), wherein the opening (22) in the second end plate (18) is sealed in a fluid-tight manner by the cover (50), characterized in that a sealing interface (80) is disposed between the second front face (16) of the first filter element (10) and the second front face (46) of the second filter element (40), via which the two filter elements (10, 40) seal directly against each other.

2. The filter system according to claim 1, wherein the sealing interface (80) comprises a sealing surface (25) on a support tube (24) of the first filter element (10) opposite a clean-sided outlet (110) and at least one sealing element (60, 62, 64) disposed on the second filter element (40), which seals against the sealing surface (25) in the axial and / or radial direction (72, 74).

3. The filter system according to claim 1 or 2, wherein the sealing interface (80) comprises a sealing element (60), in particular a gasket, which is arranged on a circumferential projection (52) which protrudes from the outer front face of the cover (50) in the axial direction (72) of the cover (50), wherein the sealing element (60) seals against a support tube (24) of the first filter element (10) in the radial direction (74).

4. The filter system according to claim 1 or 2, wherein the sealing interface (80) comprises a sealing element (62), which is disposed on a circumferential edge (51) of the cover (50) and which seals against a support tube (24) of the first filter element (10) in the radial direction (74).

5. The filter system according to claim 1 or 2, wherein the sealing interface (80) on the front face (46) of the second filter element (40), in particular on the cover (50), comprises a sealing element (64), in particular a gasket or a sealing projection (43), which seals in the axial direction (72) against an edge (26, 29) of the support tube (24) of the first filter element (10) pointing inwards in the radial direction (74).

6. The filter system according to claim 1, wherein the sealing interface (80) comprises a region (15) of the second end plate (18) of the first filter element (10), which is opposite a clean-sided outlet (110) in the axial direction (72), and at least one sealing surface (45) on the second filter element (40).

7. The filter system according to claim 6, wherein the second end plate (18) of the first filter element (10) protrudes inwardly in the radial direction (74) beyond the filter medium (11).

8. The filter system according to one of the claims 6 or 7, wherein the region (15) is disposed at an inner edge of the second end plate (18) of the first filter element (10), which seals against a sealing surface (45) on a circumferential surface (74) of a circumferential projection (52) disposed on the cover (50), which projection extends in an axial direction (72) away from the cover (50), in particular wherein a web (114) pointing in the axial direction (72) engages in a groove (17) of the second end plate (18) at the second housing component (106).

9. The filter system according to one of the claims 6 or 7, wherein the region (15) of the second end plate (18) of the first filter element (10) seals against a sealing surface (45) of a circumferential projection (52) disposed on an interior side of the cover (50) in the radial direction (74), which projection extends away from the cover (50) in the axial direction (72), wherein the projection (52) engages in a groove (19) in the end plate (18), in particular wherein an inner edge of the second end plate (18) of the first filter element (10) is supported in the axial direction (72) by a web (118) on the second housing component (106) in the radial direction (74).

10. The filter system according to one of the claims 6 or 7, wherein the region (15) is disposed at an inner edge of the second end plate (18) of the first filter element (10), which seals against a sealing surface (45) on a circumferential surface (74) of a circumferential projection (52) disposed on the cover (50), which projection extends in an axial direction (72) away from the cover (50).

11. The filter system according to one of the claims 6 or 7, wherein the region (15) is disposed on a front face (58) pointing inward in an axial direction (72) of a radial overhang (20) of the second end plate (18) of the first filter element (10) that extends within the cross-section of the filter medium (11), which seals against a sealing surface (45) on a front face of the cover (50). in particular wherein the support tube (24) features a circumferential edge (23) pointing inward in the radial direction (74), which is embedded in the radial overhang (20).

12. The filter system according to one of the preceding claims, wherein a front face (112) of the second housing component (106) is curved inward.

13. The filter system according to one of the preceding claims, wherein the front face (112) of the second housing component (106) features an opening which extends at least partially over the second front face (46) of the second filter element (40).