Gas Filter System

Abstract

The present invention relates to a gas filter system (10) comprising a housing (12) having a sealing projection (52) and a housing groove (50), an outer filter element (20) having a first filter medium (22) and a first end cap (24), and an inner filter element (30) having a second filter medium (32) and a third end cap (34), wherein the first end cap (24) has a first axial end cap projection (42) and the third end cap (34) has a second axial end cap projection (44), both end cap projections (42, 44) being disposed within the housing groove (50), the first and second end cap projections (42, 44) forming a common groove (46) into which protrudes a sealing projection (52) that sealingly abuts against the first and third end caps (24, 34). The present invention further relates to the use of the outer filter element (20) and / or the inner filter element (30) in such a gas filter system (10).

Description

[Technical Field]

[0001] The present invention relates to a gas filter system that includes an inner filter element, an outer filter element surrounding the inner filter element, and a housing sealingly abutting the outer and inner filter elements. [Background technology]

[0002] In some applications, a gas stream must be filtered through two filter elements. Typically, the gas flows through the first filter element, followed by the pre-filtered gas flowing through the second filter element. The filter elements can be arranged in a common housing. This type of filter system is used, for example, to filter combustion air in large combustion engines such as trucks and construction vehicles. Another application is filtering air for fuel cells. In such applications, one filter element is typically adapted to filter particles, while the other is adapted to adsorb or absorb harmful gases.

[0003] German Patent Application Publication No. 102018215603 discloses a gas filter system having a first filter element surrounding a second filter element. At first axial ends, the open end caps of the two filter elements are associated with a clean air outlet. At second axial ends, the first (outer) filter element has an open end cap, and the second (inner) filter element has a closed end cap. The closed end cap of the inner filter element is arranged to close the opening of the end cap of the outer filter element at the second axial end.

[0004] U.S. Patent No. 5,415,677 discloses a gas filter system having a first (outer) filter element and a second (inner) filter element disposed within a housing, the filter elements having end caps separated by a protrusion on the housing.

[0005] SUMMARY OF THE INVENTION It is an object of the present invention to provide a gas filter system with an improved seal between two filter elements and a housing suitable for joint use.

[0006] This is achieved by a gas filter system according to claim 1, by the use of a filter element according to claim 15 and by filter elements according to claims 16 and 18. Advantageous embodiments are set out in the dependent claims and in the description. Summary of the Invention

[0007] According to the present invention, there is provided a gas filter system comprising a housing having a seal projection and a housing groove, the seal projection being disposed within the housing groove.

[0008] The gas filter system further includes an outer filter element and an inner filter element. The outer filter element has a first filter medium disposed between a first end cap and a second end cap. The inner filter element has a second filter medium disposed between a third end cap and a fourth end cap. The first and third end caps are open. Preferably, the first and second end caps have central openings, allowing the inner filter element to be disposed inside the outer filter element. Meanwhile, filtered air can flow out through the third end cap.

[0009] The first filter medium can be arranged to surround the second filter medium, such that the first end cap of the outer filter element surrounds the third end cap of the inner filter element. In other words, the first and third end caps at least partially overlap in the axial direction of the gas filter system. The filter elements are hollow. The filter mediums may be arranged to form a hollow cylinder or a hollow cone, preferably with a circular or elliptical cross section. Each filter medium surrounds a longitudinal axis. In particular, the filter mediums are arranged concentrically about a common longitudinal axis. Directions such as radial and axial refer to the longitudinal axis. As a general rule, the first and third end caps are associated with the first axial end, and the second and fourth end caps are associated with the second axial end. The longitudinal axes of the inner filter element and the outer filter may be inclined relative to each other. For example, the outer filter element may be hollow cylindrical and have a common longitudinal axis with the filter housing, the inner filter element may be hollow conical, and a fourth end cap located opposite the open first and third end caps may have a smaller diameter than the third end cap and its center may be laterally offset relative to the center of the outer filter element or the filter housing.

[0010] Additionally, the first end cap has a first axial end cap protrusion and the third end cap has a second axial end cap protrusion, i.e., the first end cap and the third end cap each have a protrusion that protrudes axially beyond the first or second filter media.

[0011] The first end cap projection and the second end cap projection are disposed within the housing groove and are capable of sealingly engaging with the housing.

[0012] The first and second end cap projections form a common groove into which protruding seal projections sealingly abut against the first and third end caps. In other words, the first and second end cap projections are each sealingly received in a respective groove portion of the housing groove separated by the seal projection. Preferably, the seal projections sealingly abut against the first and second end cap projections within the common groove. Each end cap projection preferably forms one side of the common groove. Particularly preferably, each projection forms one half of the common groove. In particular, the first and second end cap projections are disposed at the same axial height along the longitudinal axis.

[0013] During use of the gas filter system, gas flow typically first passes through the first filter medium of the outer filter element and then through the second filter medium of the inner filter element, with the gas flow flowing from radially outward to radially inward, and clean gas exiting the filter system axially, preferably through a central opening in the third end cap of the inner filter element.

[0014] According to the present invention, when the outer filter element is placed around the inner filter element for use in a gas filter system, the first end cap of the outer filter element surrounds the third end cap of the inner filter element. In other words, the first and third end caps at least partially overlap each other in the axial direction. In a preferred embodiment, the first and third end caps are positioned at the same axial height along the longitudinal axis. In this mounted state, the first and third end caps are sealed to the housing, preferably radially, by the sealing protrusions. Thus, the inner and outer filter elements are indirectly sealed to each other at the first axial end. By sealing the first and third end caps to the housing, the intermediate space between the first and second filter media is sealed at the first end. Thus, the gas to be filtered flows continuously through the two filter media.

[0015] At the second axial end, the filter elements may be sealed to the housing and / or each other. Preferably, both the first filter element and the second filter element are closed at the second end. In particular, the second and / or fourth end caps are integrally closed. Alternatively, a closing means, such as a closed end face of a support tube, may be sealingly attached to the second or fourth end cap.

[0016] Typically, the housing includes a first housing portion associated with the first end and a second housing portion associated with the second end. The inlet may be formed in either the first or second housing portion. The outlet is preferably formed in the first housing portion. The outlet may be in fluid communication with the clean side of the inner filter element.

[0017] In a preferred embodiment of the gas filter system, the first axial end cap projection of the outer filter element has a first sealing surface facing the common groove, preferably radially, for sealingly abutting against the sealing projection of the housing, thereby improving the sealing effect. The first sealing surface is preferably directed radially inward.

[0018] Furthermore, in a preferred embodiment of the gas filter system, the second axial end cap projection of the inner filter element has a second sealing surface facing the common groove, preferably radially, for sealingly abutting against the sealing projection of the housing, thereby further improving the sealing effect. The second sealing surface is preferably directed radially outward.

[0019] Generally, the sealing surfaces described in the context of the present invention are softer than the mating parts they seal against. In particular, each sealing surface is made of polyurethane, preferably foamed polyurethane. The respective mating parts may also be made of hard plastic.

[0020] In another preferred embodiment, the common groove extends along the inner periphery of the first end cap and / or the outer periphery of the third end cap, thereby providing a uniform seal between the filter elements around the entire periphery.

[0021] In another preferred embodiment of the gas filter system, the common groove has at least one radial projection and / or at least one radial recess relative to the longitudinal axis of the gas filter system. Typically, the sealing projections have corresponding radial projections and / or recesses. This allows for an anti-rotation configuration of the filter elements, thus enhancing the defined sealing contact. Furthermore, it also prevents the use of unsuitable filter elements.

[0022] In a preferred embodiment of the gas filter, the common groove has a plurality of radial projections and a plurality of radial recesses, and these projections and recesses are particularly evenly distributed around the circumference. In general, the sealing projections replicate the wave-like shape of the common groove. This allows the filter elements to be positioned more accurately relative to one another. Furthermore, the even distribution of the projections and / or recesses simplifies the installation of the filter system.

[0023] In a preferred embodiment, the first end cap projection and the second end cap projection form a common web with a common groove, which allows for the formation of a seal portion that is defined to be received in the housing groove.

[0024] Preferably, the common web is formed as a circular ring with a constant, in particular radial, width. Similarly, the housing groove is preferably formed with a constant (radial) width. A wavy sealing projection may divide the housing groove into two groove portions with different widths.

[0025] The outer filter element may be closed on the side opposite the first end cap, in particular by a second end cap, which may be a monolithic closed end cap, or a closure means may be permanently attached to the outer filter element for sealing the second end cap.

[0026] The inner filter element may be closed on the side opposite the third end cap, in particular by a fourth end cap, which may be a monolithic closed end cap, or a closure means may be permanently attached to the inner filter element for sealing the fourth end cap.

[0027] The end caps may comprise polyurethane, particularly foamed polyurethane. The second and fourth end caps may comprise or include a hard plastic. Such plastic end caps may be glued to the respective filter media, further improving the sealing effect.

[0028] The first and second end cap projections may be integrally formed with the first or third end cap, respectively, further simplifying manufacturing of the filter element. In a preferred embodiment of the gas filter system, the first end cap and / or the third end cap are monolithic foam components.

[0029] Preferably, the first and / or third end caps are made of foam, preferably polyurethane foam. The foam end caps can be directly molded onto the first or second filter media, respectively. This simplifies the manufacturing process. Furthermore, polyurethane foam has good sealing properties.

[0030] In a further preferred embodiment of the gas filter system, the sealing protrusions are formed to be complementary to the common grooves of the first and second end caps. In other words, the sealing protrusions can be designed to follow the shape of the common groove. This promotes uniform contact of the sealing protrusions and further improves the sealing effect.

[0031] The housing may have a central tube that extends into the inner filter element at the third end cap when the filter system is installed, the central tube providing a guide for the inner filter element and supporting the second filter medium.

[0032] More preferably, the housing groove is adapted to press the first and second end cap projections against the sealing projections, particularly in the radial direction, which can further improve the sealing effect.

[0033] In a preferred embodiment of the gas filter system, the first or second filter medium, in particular the second filter medium of the inner filter element, has gas adsorption properties and preferably comprises activated carbon.

[0034] In a preferred embodiment of the gas filter, the first or second filter medium, in particular the first filter medium of the outer filter element, is made of cellulose.

[0035] Preferably, the first pass filter element is designed to filter particles and the second pass filter element is designed to adsorb harmful gases.

[0036] The first and / or second filter medium may be pleated, the pleated filter medium being arranged to form a circumferentially closed filter bellows, e.g., having a cylindrical or conical, preferably circular or elliptical, cross section.

[0037] In a preferred embodiment of the gas filter system, the first end cap projection has at least one stepped cross section, and the second end cap projection has at least one complementary stepped cross section. Preferably, the first and / or second end cap projections have multiple stepped cross sections, which are evenly spaced or formed, particularly around the circumference of each end cap projection. This allows for particularly accurate positioning of the filter element. The axially stepped configuration allows for radial overlapping areas on the end cap projection with the other end cap.

[0038] The invention also relates to the use of an outer filter element and / or an inner filter element in a gas filter system according to the invention, as described above.

[0039] Furthermore, the invention relates to a filter element according to claim 16 and a filter element according to claim 18 for use in a gas filter system according to the invention.

[0040] A first gas filter element according to the present invention includes a first end cap and a second end cap, the first end cap having a filter medium surrounding a hollow interior, the first end cap being open, and the first end cap having an axial end cap protrusion disposed on an inner periphery of the first end cap and having a radially inward-facing sealing surface, preferably having at least one radial protrusion and / or recess.

[0041] The open end cap is annular and typically has a circular or elliptical cross section. The axial end cap projection typically has a similar outer shape. The sealing surface may have multiple radial projections and / or recesses evenly distributed around the circumference. The outer surface of the axial end cap projection is preferably circular or elliptical, without any projections or recesses. This allows the width of the axial end cap projection to vary.

[0042] Such a filter element can be used as a replaceable outer filter element in the claimed filter system. The sealing surface is designed to be complementary to the corresponding surface of the sealing projection on the housing. The filter element may be designed for filtering particles and may include or be made of cellulose, or may have gas adsorption properties and include activated carbon.

[0043] A further gas filter element according to the present invention includes a filter medium disposed between a third end cap and a fourth end cap and surrounding a hollow interior, wherein at least the third end cap is open and has an axial end cap protrusion disposed on the outer periphery of the third end cap and having a radially outwardly facing sealing surface, and preferably the sealing surface of the axial end cap protrusion has at least one radial protrusion and / or recess.

[0044] The open end cap is annular and typically has a circular or elliptical cross section. The axial end cap projection typically has a similar shape. The sealing surface may have multiple radial projections and / or recesses evenly distributed around the circumference. The radial inner surface of the axial end cap projection is preferably circular or elliptical, without any projections or recesses. This allows the width of the axial end cap projection to vary.

[0045] Such a filter element can be used as a replaceable inner filter element in the claimed filter system. The sealing surface is designed to be complementary to a corresponding surface of the sealing projection on the housing. The filter element may have gas adsorption properties, may include activated carbon, or may be designed for filtering particles, and may include or be made of cellulose.

[0046] Other advantages and features of the present invention will be apparent from the following description of embodiments of the invention, with reference to the drawings showing important details, and from the claims. The individual features as described above or below may be implemented individually or in any useful combination in variants of the invention. [Brief explanation of the drawings]

[0047] [Figure 1] 1 is a schematic cross-sectional view of a gas filter system including an outer filter element, an inner filter element, and a housing according to the present invention. [Figure 2] 2 is a first enlarged cross-sectional view of a first end of the filter system of FIG. 1. [Figure 3] FIG. 2 is a cross-sectional top view of the gas filter system of FIG. 1. [Figure 4] 2 is a second enlarged cross-sectional view of the first end of the filter system of FIG. 1. [Figure 5] 2 is a schematic perspective view of an outer filter element of the gas filter system of FIG. 1. [Figure 6] 2 is a schematic perspective view of an inner filter element of the gas filter system of FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0048] 1 illustrates a gas filter system 10. The filter system 10 includes a housing 12. The housing has a first housing portion 14 and a second housing portion 16 that are attachable to one another. An inlet 18 allows gas to enter the housing 12. Here, the inlet is formed in the first housing portion 14. A filtered gas outlet 19 is also formed in the first housing portion 14. The housing portions 14, 16 may be made of metal and / or rigid plastic.

[0049] The filter system 10 further includes an outer filter element 20 (see also FIG. 5). The outer filter element 20 has a first filter medium 22. The first filter medium 22 is housed between a first end cap 24 and a second end cap 26. The first filter medium 22 circumferentially surrounds a longitudinal axis 28. The first filter medium 22 may be constructed from pleated cellulose paper.

[0050] The filter system 10 further includes an inner filter element 30 (see also FIG. 6). The inner filter element 30 has a second filter medium 32. The second filter medium 32 is housed between a third end cap 34 and a fourth end cap 36. The second filter medium 32 also circumferentially surrounds the longitudinal axis 28. The second filter medium 32 may include activated carbon for gas adsorption properties.

[0051] The inner filter element 30 is disposed inside the outer filter element 20. Both filter elements 20, 30 are disposed within the housing 12, where the first and second filter media 22, 32 are concentric with each other and with respect to the longitudinal axis 28.

[0052] At the first end of the filter system 10, a first end cap 24 is positioned surrounding a third end cap 34 (see also FIG. 2). The first end cap 24 and the fifth end cap 34 each have a central opening (see FIGS. 4 and 3, respectively). The outlet 19 is in fluid communication with a clean side 40 within the inner filter element 30 (see FIG. 1). The first end cap 24 of the outer filter element 20 has a first axial end cap projection 42. That is, the first end cap projection 42 projects axially relative to the longitudinal axis 28 beyond the first filter medium 22. The first end cap projection 42 may also extend parallel to the longitudinal axis 28. Preferably, the first end cap projection 42 is located on, and specifically formed on, the face of the first end cap 24 opposite the first filter medium 22.

[0053] The third end cap 34 of the inner filter element 30 has a second axial end cap projection 44. The second end cap projection 44 is arranged and specifically configured similarly to the first end cap projection 42.

[0054] As shown, the first axial end cap projection 42 and the second axial end cap projection form a common groove 46. According to the illustrated embodiment, the common groove 46 is open at the bottom. In other words, the two end caps 24, 34 are radially spaced apart from each other, i.e., the first and third end caps 24, 34 do not contact each other.

[0055] The housing 12, here the first housing part 14, has a housing end face 48. The housing end face 48 may be perpendicular to the longitudinal axis 28. The housing end face 48 forms a housing groove 50. The first axial end cap projection 42 and the second axial end cap projection 44 are disposed within the housing groove 50, particularly for sealing abutment. In other words, the housing groove 50 may encompass the end cap projections 42, 44. The seal projection 52 is disposed within and specifically configured in the housing groove 50. The seal projection 52 separates two groove portions within the housing groove. The first and second seal projections 42, 44 are each received within one of the groove portions of the housing groove.

[0056] The seal projection 52 projects into the common groove 46 of the first and second end cap projections 42, 44 for sealing engagement with the first and third end caps 24, 34. The seal projection 52 may project from the housing groove 50.

[0057] The first end cap 24 and the third end cap 34 are sealed to each other and to the housing 12 by the sealing projections 52, which establish a radial seal.

[0058] In the illustrated embodiment, the first end cap 24 having the first end cap projection 42 is integrally formed from foamed polyurethane, as is the third end cap 34 having the second end cap projection 46. In other words, the end caps 24, 34, each with its respective end cap projection 42, 44, are monolithic components. The second and fourth end caps 26, 36 may also include, and particularly be constructed from, foamed polyurethane.

[0059] The central tube 54 of the housing 12 is retained in an axial collar 56 of the first housing portion 14. The collar 56 has an outlet port 19. The collar 56 may protrude axially beyond the housing end face 48. The central tube 54 extends through an opening in the third end cap 34 toward the fourth end cap 36. The central tube 54 may be constructed of a hard plastic.

[0060] At the second end of the filter system 10 are a second end cap 26 and a fourth end cap 36. The second end cap 26 may have a central opening, preferably closed by a closure means. The fourth end cap 36 is closed. In the illustrated embodiment, the fourth end cap 36 is a monolithic closed end cap.

[0061] The second end cap 26 may have a housing spacer 58 that abuts the housing 12, in this case the second housing portion 16. The housing spacer 58 may provide axial distance between the second end cap 26 and the bottom surface of the housing 12. Preferably, the housing spacer 58 is integrally formed with the second end cap 26.

[0062] The second end cap 26 and / or the fourth end cap 36 may be integrally formed from foamed polyurethane. In other words, the second end cap 26 and / or the fourth end cap 36 may be a monolithic component that may be molded to the first or second filter media 22, 32, respectively.

[0063] The outer filter element 20 may have a base plate 60 that axially closes the outer filter element 20. The base plate 60 is preferably constructed from a hard plastic or metal. Preferably, the base plate 60 is recessed into the second end cap 26.

[0064] The outer filter element 20 may have at least one filter spacer 62 separating the inner filter element 30 from the outer filter element 20. The filter spacer 62 is preferably integrally formed on the bottom plate 60.

[0065] The outer filter element 20 may have a support tube 64 disposed radially inside the first filter medium 22. This allows for radial support of the first filter medium 22. The support tube 64 may be formed integrally with the bottom plate 60.

[0066] Referring now to FIG. 2, a first end of the filter system of FIG. 1 is shown in a first enlarged cross-sectional view.

[0067] At a first end of the filter system 10, the outer filter element 20 is shown surrounding the inner filter element 30. The end cap projections 42, 44 of each end cap 20, 30 are positioned within the housing grooves 50.

[0068] As shown, the sealing projection 52 extends into the common groove 46 formed between the end cap projections 42, 44. The sealing projection 52 can sealingly abut a first sealing surface 66 of the first end cap projection 42 facing the common groove 46 and a second sealing surface 68 of the second end cap projection 44 facing the common groove 46.

[0069] According to the illustrated embodiment, the sealing projection 52 can be configured to widen the common groove 46 when the sealing projection 52 is disposed therein. This effectively allows the first end cap projection 42 and / or the second end cap projection 44 to radially press against the outer or inner wall of the housing groove 50, respectively, in addition to the sealing contact of the sealing projection 52 with the end cap projections 42, 44. In other words, the third sealing surface 70 can be formed radially outward on the first end cap projection 42, and / or the fourth sealing surface 72 can be formed radially inward on the second seal projection 44. In other words, the housing groove 50 can be adapted to press the first and second end cap projections 42, 44 against the sealing projections 52, particularly in the radial direction. This further improves the sealing effect.

[0070] Additionally, housing 12 may be configured to sealingly engage fifth sealing surface 74 of first end cap projection 42 and / or sixth sealing surface 76 of second end cap projection 44. Preferably, positioning first housing portion 14 relative to second housing portion 16 slightly compresses first and / or second filter elements 20, 30 such that sealing projections 42, 44 are securely received within housing groove 50 (see FIG. 1 ).

[0071] 3 is a cross-sectional view of the gas filter system 10 of the previous figure, taken perpendicular to the longitudinal axis and through the end cap projections 42, 44 and the seal projection 52. In accordance with the present invention, the seal projection 52 is disposed within the common groove 46.

[0072] According to this embodiment, the first end cap projection 42 and the second end cap projection 44 are circumferentially closed. The two end cap projections 42, 44 form a common web 78. The common web 78 may be circumferentially closed, as shown. Preferably, as shown, the common web 78 is annular, and in particular has a constant radial width 80 between an inner diameter 82 and an outer diameter 84. The inner diameter 82 and / or the outer diameter 84 preferably relate to the longitudinal axis 28 of the gas filter system 10.

[0073] As shown, the common groove 46 may be closed in the circumferential direction. Preferably, the common groove 46 is formed in the circumferential direction by the first end cap projection 42 and the second end cap projection 44. The common groove 46 may have at least one radial protrusion 86 or one radial recess 88. Preferably, as shown, the common groove 46 has a plurality of radial protrusions 86 and a plurality of radial recesses 88, particularly formed with uniform distribution in the circumferential direction. In other words, the common groove 46 may be designed in a wavy pattern around the central radius 90. This allows the filter elements 20, 30 to have a twist-resistant configuration relative to each other and within the housing 12, thereby providing a good sealing configuration.

[0074] The sealing projection 52 may be formed to be complementary to the common groove 46 of the first end cap projection 42 and the second end cap projection 44. In other words, the sealing projection 52 follows the wave-like shape of the common groove 46.

[0075] Referring now to FIG. 4, the first end of the filter system 10 of FIGS. 1 and 2 is shown in a second enlarged cross-sectional view through the radial projection 86.

[0076] As shown, the first end cap projection 42 and / or the second end cap projection 44 may have axially stepped sections 92, 94 (see also FIGS. 5 and 6). The stepped section 92 of the first end cap projection 42 may be radially recessed from the first end cap 24, as shown. The stepped section 94 of the second end cap projection 44 may be complementary radially protruding relative to the third end cap 34. Preferably, the radially protruding stepped section 94 overlaps the radially recessed stepped section 92, which allows the end caps 24, 34 to be positioned particularly close together. Figure 5 is a schematic perspective view of outer filter element 20 of gas filter system 10 of Figure 1. Outer filter element 20 includes a hollow cylindrical support tube 64 as shown.

[0077] According to the illustrated embodiment, the outer filter element 20 has a plurality of stepped sections 92 in the first end cap projections 42. Here, the stepped sections 92 are radially recessed and evenly distributed around the inner circumference of the first end cap 24 having the end cap projections 42.

[0078] As shown, the first end cap projection 42 may have a non-stepped cross section 96. The non-stepped cross sections 96 may alternate with the stepped cross sections 92.

[0079] FIG. 6 is a schematic perspective view of inner filter element 30 of gas filter system 10 of FIG.

[0080] According to the illustrated embodiment, the outer filter element 30 has a plurality of stepped sections 94 in the second end cap projections 44. Here, the stepped sections 94 protrude radially and are evenly distributed around the circumference of the third end cap 34 having the second end cap projections 44.

[0081] As shown, the second end cap projection 44 may have non-stepped cross sections 98. The non-stepped cross sections 98 may alternate with the stepped cross sections 94.

[0082] The stepped sections 92, 94 and / or non-stepped sections 96, 98 are preferably formed in complementary pairs, respectively, so that when the outer filter element 20 is positioned around the inner filter element 30, the stepped sections 92, 94 and / or non-stepped sections 96, 98 preferably engage with each other.

[0083] Briefly, the present invention provides a gas filter system (10) comprising: a housing (12) having a seal projection (52) in a housing groove (50); an outer filter element (20) having a first filter medium (22) and a first end cap (24); an inner filter element (30) having a second filter medium (32) and a third end cap (34); the first end cap (24) has a first axial end cap projection (42), the third end cap (34) has a second axial end cap projection (44), both end cap projections (42, 44) disposed within a housing groove (50); The present invention relates to a gas filter system (10) in which first and second end cap projections (42, 44) form a common groove (46) into which project sealing projections (52) that sealingly abut against the first and third end caps (24, 34). The present invention also relates to the use of an outer filter element (20) and / or an inner filter element (30) in such a gas filter system (10). [Explanation of symbols]

[0084] Gas filter systems 10 Housing 12 First housing part 14 Second housing part 16 Inlet 18 Outlet 19 Outer filter element 20 First filter element 22 First End Cap 24 Second End Cap 26 Longitudinal axis 28 Inner filter element 30 Second filter element 32 Third End Cap 34 4th end cap 36 Clean side 40 First end cap protrusion 42 Second end cap protrusion 44 common groove 46 Housing end face 48 Housing groove 50 Seal protrusion 52 central tube 54 Axial Collar 56 Housing Spacer 58 Bottom plate 60 Filter spacer 62 Support tube 64 First sealing surface 66 Second sealing surface 68 Third sealing surface 70 Fourth sealing surface 72 5th sealing surface 74 6th sealing surface 76 Common Web 78 Width 80 Inner diameter 82 Outer diameter 84 Radial convexity 86 Radial recess 88 Center Radius 90 Stepped cross section 92 Stepped cross section 94 Non-stepped section 96 Non-stepped section 98

Claims

1. A gas filter system (10) comprising: a housing (12) having a seal projection (52) and a housing groove (50), the seal projection (52) being disposed within the housing groove (50); an outer filter element (20) having a first filter medium (22) disposed between a first end cap (24) and a second end cap (26); an inner filter element (30) having a second filter medium (32) disposed between a third end cap (34) and a fourth end cap (36); the first and third end caps (24, 34) are open; the first filter medium (22) is positionable to surround the second filter medium (32) such that the first end cap (24) of the outer filter element (20) surrounds the third end cap (34) of the inner filter element (30); The first end cap (24) has a first axial end cap projection (42) disposed within the housing groove (50), and the third end cap (34) has a second axial end cap projection (44) disposed within the housing groove (50); The first and second end cap projections (42, 44) form a common groove (46), and the sealing projections (52) that sealingly abut against the first and third end caps (24, 34) project into the common groove (46).

2. 2. The gas filter system (10) of claim 1, wherein the first axial end cap projection (42) of the outer filter element (20) has a first sealing surface (66) facing the common groove (46), preferably in a radial direction, for sealingly abutting against the sealing projection (52) of the housing (12).

3. 3. The gas filter system (10) of claim 1 or 2, wherein the second axial end cap projection (44) of the inner filter element (30) has a second sealing surface (68) facing the common groove (46), preferably in a radial direction, for sealingly abutting against the sealing projection (52) of the housing (12).

4. A gas filter system (10) according to any one of claims 1 to 3, wherein the common groove (46) extends along the inner circumference of the first end cap (24) and / or along the outer circumference of the third end cap (34).

5. A gas filter system (10) according to any one of claims 1 to 4, wherein the common groove (46) has at least one radial protrusion (86) and / or at least one radial recess (88) relative to the longitudinal axis (28) of the gas filter system (10).

6. A gas filter system (10) as described in claim 5, wherein the common groove (46) has a plurality of radial protrusions (86) and a plurality of radial recesses (88), and the protrusions (86) and the recesses (88) are formed in a manner particularly uniformly distributed around the circumference.

7. The gas filter system (10) of any one of claims 1 to 6, wherein the first end cap projection (42) and the second end cap projection (44) form a common web (78) having the common groove (46).

8. The gas filter system (10) of claim 7, wherein the common web (78) is formed as a circular or elliptical ring having a constant width (80).

9. The gas filter system (10) of any one of claims 1 to 8, wherein the first end cap (24) and / or the third end cap (34) are monolithic foam components.

10. The gas filter system (10) of any one of claims 1 to 9, wherein the sealing projection (52) is formed complementarily to the common groove (46) of the first end cap projection (42) and the second end cap projection (44).

11. The gas filter system (10) of any one of claims 1 to 10, wherein the housing groove (50) is adapted to press the first and second end cap projections (42, 44) against the sealing projection (52).

12. The gas filter system (10) according to any one of claims 1 to 11, wherein the first or second filter medium (22, 32), in particular the second filter medium (32) of the inner filter element (30), has gas adsorption properties and preferably comprises activated carbon.

13. 13. The gas filter system (10) according to any one of claims 1 to 12, wherein the first or second filter medium (22, 32), in particular the first filter medium (22) of the outer filter element (20), is made of cellulose.

14. 14. The gas filter system (10) of claim 1, wherein the first end cap projection (42) has at least one stepped cross section (92) and the second end cap projection (44) has at least one complementary stepped cross section (94).

15. Use of an outer filter element (20) and / or an inner filter element (30) in a gas filter system (10) according to any one of claims 1 to 14.

16. A gas filter element (20) having a filter medium (22) surrounding a hollow interior and disposed between a first end cap (24) and a second end cap (26), At least the first end cap (24) is open, the first end cap (24) has an axial end cap projection (42), the end cap projection (42) is disposed on an inner circumference of the first end cap (24) and has a radially inward facing sealing surface (66).

17. 17. The gas filter element (20) of claim 16, wherein the sealing surface (66) of the end cap projection (42) has at least one radial protrusion (86) and / or recess (88).

18. A gas filter element (30) having a filter medium (32) surrounding a hollow interior and disposed between a third end cap (34) and a fourth end cap (36), At least the third end cap (34) is open, the third end cap (34) has an axial end cap projection (44), the end cap projection (44) is disposed on the outer periphery of the third end cap (34) and has a radially outward facing sealing surface (68).

19. 20. The gas filter element (20) of claim 18, wherein the sealing surface (68) of the axial end cap projection (44) comprises at least one radial protrusion (86) and / or recess (88).

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