Gas filtration system

Abstract

The invention relates to a gas filtration 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 arranged in the housing recess (50); the first and second end cap projections (42, 44) form a common groove (46) into which the sealing projection (52) projects for sealing against the first and third end caps (24, 34) at the common groove (46). The invention also relates to the use of the outer filter element (20) and / or the inner filter element (30) in such a gas filtration system (10).

Description

Technical Field

[0001] The present invention relates to a gas filter system comprising an inner filter element, an outer filter element surrounding the inner filter element, and a housing for sealing against the outer and inner filter elements. Background Art

[0002] In some applications, it is necessary to filter the airflow with two filter elements. Typically, the gas flows through the first filter element, and then, the pre-filtered gas flows through the second filter element. The filter element can be arranged in a common housing. Such a filter system is used, for example, to filter the combustion air of a large internal combustion engine, such as for trucks, construction vehicles, etc. Another application is to filter the air for a fuel cell. For such an application, typically one filter element is suitable for filtering particles, and the other filter element is suitable for adsorbing or absorbing harmful gases.

[0003] DE 102018215603 A1 discloses a gas filtration system, which has a first filter element surrounding a second filter element. At the first axial end, the open end caps of two filter elements are associated with an outlet for clean air. At the second axial end, the first (external) 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 in the end cap of the outer filter element at the second axial end.

[0004] US 5,415,677 A discloses a gas filter system having a first (outer) filter element and a second (inner) filter element disposed in a housing. The filter element comprises end caps separated by protrusions of the housing.

[0005] It is an object of the present invention to provide a gas filtering system having an improved seal between a housing and two filter elements adapted for joint use.

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

[0007] According to the present invention, a gas filter system is provided, which comprises a housing having a sealing protrusion and a housing groove, wherein the sealing protrusion is arranged in the housing groove.

[0008] In addition, the gas filter system comprises an outer filter element and an inner filter element. The outer filter element has a first filter medium arranged between the first end cap and the second end cap. The inner filter element has a second filter medium arranged between the third end cap and the fourth end cap. The first end cap and the third end cap are open. Preferably, the first and second end caps have a central opening. This allows the inner filter element to be placed inside the outer filter element. On the other hand, the (filtered) air can flow out through the third end cap.

[0009] The first filter medium may be arranged to surround the second filter medium so 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 end cap and the third end cap overlap at least partially in the axial direction of the gas filter system. The filter element is a hollow body. The filter medium may be arranged to form a hollow cylindrical or hollow conical body, and the cross section may preferably be circular or elliptical. Each filter medium surrounds the longitudinal axis. In particular, the filter medium may be arranged concentrically with the common longitudinal axis. Direction indications such as radial or axial refer to the longitudinal axis. In principle, the first end cap and the third end cap are associated with the first axial end; 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 also be inclined relative to each other. For example, the outer filter element may be hollow cylindrical and have the same longitudinal axis as the filter housing, and the inner filter element may be hollow conical, wherein the diameter of the fourth end cap opposite to the first and third end caps of the opening may be smaller than the diameter of the third end cap, and may be arranged so that its center is laterally displaced relative to the center of the outer filter element or the filter housing.

[0010] Furthermore, the first end cap has a first axial end cap protrusion, and the third end cap has a second axial end cap protrusion. In other words, both the first end cap and the third end cap each have a protrusion that axially protrudes beyond the first filter medium or the second filter medium.

[0011] The first end cap protrusion and the second end cap protrusion are arranged in the housing groove. The end cap protrusions can sealably engage the housing.

[0012] The first end cap protrusion and the second end cap protrusion form a common groove, and the sealing protrusion extends into the common groove for abutting against the first end cap and the third end cap seal at the common groove. In other words, each of the first end cap protrusion and the second end cap protrusion is sealingly received in a corresponding sub-groove of the housing groove, and the sub-groove of the housing groove is defined by the sealing protrusion. Preferably, the sealing protrusion seals against the first end cap protrusion and the second end cap protrusion in the common groove. Each end cap protrusion preferably forms one side of the common groove. It is particularly preferred that each protrusion forms half of the common groove. Specifically, the first end cap protrusion and the second end cap protrusion are arranged at the same axial height along the longitudinal axis.

[0013] During use of the gas filter system, the gas flow is usually first directed through the first filter medium of the outer filter element and then through the second filter medium of the inner filter element. The gas flow flows from the radial outside to the radial inside, and the clean gas leaves the filter system in the axial direction via the preferably central opening of the third end cap of the inner filter element.

[0014] According to the present invention, when the outer filter element is arranged 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 end cap and the third end cap overlap each other at least partially in the axial direction. In a preferred embodiment, the first end cap and the third end cap are arranged at the same axial height along the longitudinal axis. In this installed state, the first end cap and the third end cap are sealed against the housing, preferably in the radial direction by the sealing protrusion. Therefore, the inner filter element and the outer filter element are indirectly sealed to each other at the first axial end. By sealing the first end cap and the third end cap against the housing, the intermediate space between the first and second filter media is sealed at the first end. Therefore, the gas to be filtered must flow through the two filter media continuously.

[0015] At the second axial end, the filter element can be against housing and / or sealed to each other. Preferably, both the first and second filter elements are closed at the second end. Especially, the second and / or the fourth end cap can be integrally closed. Alternatively, a closure device (such as the closed end face of a support tube) can be sealingly attached to the second or the 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 at the first or second housing portion. The outlet is preferably formed at the first housing portion. The outlet may be in fluid communication with the clean side of the interior of the internal 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 for sealing against the sealing projection of the housing, preferably in a radial direction. This can improve the sealing effect. The first sealing surface is preferably directed radially inwards.

[0018] Furthermore, an embodiment of the gas filter is preferred in which the second axial end cap projection of the inner filter element has a second sealing surface facing the common groove for abutting against the sealing projection of the housing to seal, preferably in radial direction. This can further improve the sealing effect. The second sealing surface is preferably directed radially outwards.

[0019] Generally speaking, the sealing surfaces described within the context of the present invention are softer than the counterparts they will seal against. In particular, the corresponding sealing surfaces can be made of polyurethane, preferably polyurethane foam. The corresponding counterparts can be made of rigid plastic.

[0020] Another preferred embodiment provides a common groove extending along the inner circumference of the first end cap and / or along the outer circumference of the third end cap. This allows a uniform sealing effect to be achieved over the entire circumference between the filter elements.

[0021] In another preferred embodiment of the gas filter system, the common groove has at least one radial protrusion and / or at least one radial recess relative to the longitudinal axis of the gas filter system. Typically, the sealing protrusion has corresponding radial protrusions and / or recesses. This achieves an anti-rotation arrangement of the filter element. Therefore, the limited sealing contact can be enhanced. In addition, the use of an inappropriate filter element is prevented.

[0022] In addition, a preferred embodiment of the gas filter is an embodiment in which the common groove has a plurality of radial protrusions and radial recesses, which are formed on the circumference in a uniformly distributed manner. The sealing protrusions roughly replicate the corrugated shape of the common groove. This allows the filter elements to be arranged more accurately relative to each other. The uniform distribution of the protrusions and / or recesses simplifies the installation of the filter system.

[0023] A preferred embodiment provides that the first end cap projection and the second end cap projection form a common web including a common groove. This enables a defined sealing section to be formed to be received in a housing groove.

[0024] Preferably, the common web is formed as a ring with a constant width, in particular a radial width. Likewise, the housing groove is preferably formed with a constant (radial) width. The corrugated sealing protrusion can divide the housing groove into two sub-grooves with varying widths.

[0025] The outer filter element can be closed on the side opposite to the first end cap, in particular by the second end cap. The second end cap can be an integrally closed end cap. Alternatively, the closure device can be permanently fixed to the outer filter element for sealing the second end cap.

[0026] The inner filter element can be closed on the side opposite to the third end cap, in particular by the fourth end cap. The fourth end cap can be an integrally closed end cap. Alternatively, the closing device can be permanently fixed to the inner filter element for sealing the fourth end cap.

[0027] The end caps can have polyurethane, in particular made of polyurethane foam. The second and fourth end caps can also be made of or include rigid plastic. Such plastic end caps can be glued to the corresponding filter medium. This can further improve the sealing effect.

[0028] The first end cap protrusion and the second end cap protrusion can be made integrally with the first or third end cap, respectively. This further simplifies the manufacture of the filter element. A preferred embodiment of the gas filter system provides that the first end cap and / or the third end cap is an integral foam part.

[0029] Preferably, the first and / or third end cap is made of foam, preferably polyurethane foam. The foam end cap can be molded directly to the first filter medium or the second filter medium, respectively. This reduces the manufacturing effort. In addition, (polyurethane) foam has good sealing properties.

[0030] Further preferred is an embodiment of the gas filtration system in which the sealing protrusion is formed to be complementary to the common groove of the first end cap and the second end cap. In other words, the sealing protrusion can be designed to follow the shape of the common groove. This can facilitate uniform contact of the sealing protrusion and further improve the sealing effect.

[0031] The housing may have a central tube, which, in the installed state of the filter system, extends into the inner filter element at the third end cap. The central tube provides a guide for the inner filter element and provides support for the second filter medium.

[0032] It is further preferred that the housing groove is adapted to press the first end cover protrusion and the second end cover protrusion against the sealing protrusion, especially in the radial direction, which can further improve the sealing effect.

[0033] In a preferred embodiment of the gas filter system, the first filter medium or the 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 filter medium or the second filter medium, in particular the first filter medium of the outer filter element, is made of cellulose.

[0035] Preferably, the filter element through which the flow flows first is designed to filter particles and the filter element through which the flow flows second is designed to adsorb harmful gases.

[0036] The first and / or second filter medium may be pleated. The pleated medium is arranged to form a circumferentially closed filter corrugation which may have a cylindrical or conical shape, preferably with a circular or elliptical cross section.

[0037] In a preferred embodiment of the gas filter system, the first end cap protrusion has at least one stepped cross section and the second end cap protrusion has at least one complementary stepped cross section. Preferably, the first and / or second end cap protrusion has a plurality of stepped cross sections which are arranged or formed in a uniformly distributed manner, in particular on the respective circumference of the end cap protrusion. This allows a particularly precise arrangement of the filter element. The axial stepped configuration allows the formation of such an area on the end cap protrusion which overlaps with the other end cap in the radial direction.

[0038] As mentioned above, 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.

[0039] The invention further 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] The first gas filter element according to the present invention has a filter medium surrounding a hollow interior and arranged between a first end cap and a second end cap, at least the first end cap being open, wherein the first end cap has an axial end cap protrusion, which is arranged on the inner circumference of the first end cap and has a sealing surface directed radially inwards. Preferably, the sealing surface of the end cap protrusion comprises at least one radial protrusion and / or recess.

[0041] The end cap of the opening is annular and will generally have a circular or elliptical cross section. The axial end cap protrusions will generally have the same profile. The sealing surface may include a plurality of radial protrusions and / or recesses, which may be evenly distributed over the circumference. The outer surface of the axial end cap protrusion is preferably circular or elliptical without any protrusions and / or recesses. This results in a variation in the width of the axial end cap protrusion.

[0042] Such a filter element can be used as a replaceable external filter element in a filter system as claimed in the claim. The sealing surface is embodied to be complementary to a corresponding surface of a sealing protrusion of the housing. The filter element can be embodied for filtering particles and can comprise or consist of cellulose, or it can have gas adsorption properties and can comprise activated carbon.

[0043] Another gas filter element according to the invention has a filter medium surrounding the hollow interior and arranged between a third end cap and a fourth end cap, at least the third end cap being open, wherein the third end cap has an axial end cap protrusion, which is arranged on the outer circumference of the third end cap and has a sealing surface directed radially outward. Preferably, the sealing surface of the axial end cap protrusion comprises at least one radial protrusion and / or recess.

[0044] The open end cap is annular and will generally have a circular or elliptical cross section. The axial end cap protrusions will generally have the same shape. The sealing surface may include a plurality of radial protrusions and / or recesses, which may be evenly distributed over the circumference. The radial inner surface of the axial end cap protrusion is preferably circular or elliptical without any protrusions and / or recesses. This results in a variation in the width of the axial end cap protrusion.

[0045] Such a filter element can be used as a replaceable internal filter element in a filter system as claimed in the claim. The sealing surface is embodied to be complementary to a corresponding surface of a sealing protrusion of the housing. The filter element can have gas adsorption properties and can include activated carbon, or it can be embodied for filtering particles and can include or consist of cellulose. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Other advantages and features of the invention will be apparent from the following description of embodiments of the invention with reference to the accompanying drawings showing important details, and from the claims. As described above or as explained below, in variations of the invention, the various features may be implemented individually or together in any useful combination.

[0047] Figure 1 A gas filter system according to the invention is shown in a schematic cross-sectional view, comprising an outer filter element, an inner filter element and a housing.

[0048] Figure 2 The first enlarged cross-sectional view shows Figure 1 The first end of the filtration system.

[0049] Figure 3 The cross-sectional top view shows Figure 1 Gas filtration system.

[0050] Figure 4 The second enlarged cross-sectional view shows Figure 1 The first end of the filtration system.

[0051] Figure 5 A schematic perspective view shows Figure 1 External filter element for gas filtration systems.

[0052] Figure 6 A schematic perspective view shows Figure 1 Internal filter element of the gas filtration system. DETAILED DESCRIPTION

[0053] Figure 1A gas filtering system 10 is shown. The filtering system 10 comprises a housing 12. The housing has a first housing part 14 and a second housing part 16, which can be attached to each other. An inlet 18 allows gas to enter the housing 12. Here, the inlet is formed at the first housing part 14. An outlet 19 for filtered gas is also formed at the first housing part 14. The housing parts 14, 16 can be made of metal and / or rigid plastic.

[0054] The filter system 10 also includes an external filter element 20, also see Figure 5 The outer filter element 20 includes a first filter medium 22. The first medium 22 is contained between a first end cap 24 and a second end cap 26. The first filter medium 22 surrounds a longitudinal axis 28 in an annular manner. The first filter medium 22 may be made of pleated cellulose paper.

[0055] The filter system 10 also includes an internal filter element 30, also see Figure 6 The inner filter element 30 includes a second filter media 32. The second media 32 is contained between a third end cap 34 and a fourth end cap 36. The second filter media 32 also surrounds the longitudinal axis 28 in an annular manner. The second filter media 32 may include activated carbon to achieve gas adsorption properties.

[0056] The inner filter element 30 is arranged inside the outer filter element 20. Both filter elements 20, 30 are arranged inside the housing 12. Here, the first and second filter media 22, 32 are concentric with each other and with the longitudinal axis 28.

[0057] See also Figure 2 At the first end of the filter system 10, the first end cap 24 is arranged to surround the third end cap 34. Figure 4 and Figure 5 , the first end cap 24 and the third end cap 34 each have a central opening. The outlet 19 is in fluid communication with the clean side 40 within the inner filter element 30, see Figure 1 .

[0058] The first end cap 24 of the outer filter element 20 has a first axial end cap protrusion 42. In other words, the first end cap protrusion 42 protrudes beyond the first filter medium 22 in the axial direction relative to the longitudinal axis 28. The first end cap protrusion 42 can extend parallel to the longitudinal axis 28. Preferably, the first end cap protrusion 42 is arranged, in particular formed, on a side of the first end cap 24 facing away from the first filter medium 22.

[0059] 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 can be arranged, in particular formed, similarly to the first end cap projection 42.

[0060] As shown, the first axial end cap protrusion 42 and the second axial end cap protrusion form a common groove 46. According to the depicted embodiment, the common groove 46 is open at the bottom. In other words, the two end caps 24, 34 are arranged to be radially separated from each other, that is, they do not contact each other at the first end cap and the third end cap 24, 34.

[0061] The housing 12, here the first housing part 14, has a housing end face 48. The housing end face 48 can be aligned in the normal direction of the longitudinal axis 28. The housing end face 48 forms a housing groove 50. The first axial end cap protrusion 42 and the second axial end cap protrusion 44 are arranged in the housing groove 50, in particular for sealing abutment. In other words, the housing groove 50 can surround the end cap protrusions 42, 44.

[0062] The sealing protrusion 52 is arranged, in particular formed, in the housing groove 50. The sealing protrusion 52 separates two sub-grooves in the housing groove. The first and second sealing protrusions 42, 44 are each accommodated in one sub-groove of the housing groove.

[0063] The sealing protrusion 52 extends into the common groove 46 of the first and second end cap protrusions 42, 44 for sealing engagement with the first and third end caps 24, 34. The sealing protrusion 52 may extend from the housing groove 50.

[0064] The first end cover 24 and the third end cover 34 are sealed relative to each other and the housing 12 by means of the sealing projection 52. In this way, a radial seal can be established.

[0065] In the depicted embodiment, the first end cap 24 with the first end cap protrusion 42 and the third end cap 34 with the second end cap protrusion 46 are made of polyurethane foam in one piece. In other words, the end caps 24, 34 and their respective end cap protrusions 42, 44 are an integral part. The second and fourth end caps 26, 36 may also include polyurethane foam, in particular consist of it.

[0066] The center tube 54 of the housing 12 is retained at an axial collar 56 of the first housing portion 14. The collar 56 may include the outlet 19. The collar 56 may protrude axially beyond the housing end face 48. The center tube 54 extends through the opening of the third end cap 34 toward the fourth end cap 36. The center tube 54 may be made of a rigid plastic.

[0067] At the second end of the filter system 10, a second end cap 26 and a fourth end cap 36 are arranged. The second end cap 26 may have a central opening, which is preferably closed by a closure device. The fourth end cap 36 is closed. In the illustrated embodiment, the fourth end cap 36 is an integral closed end cap.

[0068] The second end cap 26 may include a housing spacer 58 that bears against the housing 12, in this case the second housing portion 16. The housing spacer 58 may provide an 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.

[0069] The second end cap 26 and / or the fourth end cap 36 can be made of polyurethane foam in one piece. In other words, the second end cap 26 and / or the fourth end cap 36 can be an integral part. They can be molded to the first filter medium or the second filter medium 22, 32 respectively.

[0070] The outer filter element 20 may have a bottom plate 60 which closes the outer filter 20 in the axial direction. The bottom plate 60 is preferably made of a rigid plastic or metal. Preferably, the bottom plate 60 is embedded in the second end cap 26.

[0071] The outer filter element 20 may include at least one filter spacer 62 that separates the inner filter element 30 from the outer filter element 20. The filter spacer 62 is preferably formed on the bottom plate 60 in a single layer.

[0072] The outer filter element 20 may have a support tube 64 which is arranged radially on the inside of the first filter medium 22. This allows the first filter medium 22 to be radially supported. The support tube 64 may be formed in one piece with the base plate 60.

[0073] Reference now Figure 2 , shown in a first enlarged cross-sectional view Figure 1 The first end of the filtration system.

[0074] The first end of the filter system 10 shows the outer filter element 20 surrounding the inner filter element 30. The end cap projections 42, 44 of the respective end caps 20, 30 are disposed in the housing recess 50.

[0075] As shown, the sealing protrusion 52 extends into the common groove 46 formed between the end cap protrusions 42, 44. The sealing protrusion 52 can sealingly abut a first sealing surface 66 of the first end cap protrusion 42 facing the common groove 46 and a second sealing surface 68 of the second end cap protrusion 44 facing the common groove 46.

[0076] According to the illustrated embodiment, when the sealing protrusion 52 is arranged in the common groove 46, the sealing protrusion 52 can be configured to widen the common groove 46. In addition to the sealing contact of the sealing protrusion 52 against the end cover protrusions 42, 44, the radial extrusion of the first end cover protrusion 42 and / or the second end cover protrusion 44 against the outer wall or the inner wall of the housing groove 50 can be achieved. In other words, the third sealing surface 70 can be formed radially outward on the first end cover protrusion 42, and / or the fourth sealing surface 72 can be formed radially inward on the second sealing protrusion 44. In other words, the housing groove 50 can be adapted to press the first end cover protrusion 42 and the second end cover protrusion 42, 44 against the sealing protrusion 52, especially in the radial direction. This can further increase the sealing effect.

[0077] Additionally, the housing 12 may be configured to sealingly engage the fifth sealing surface 74 of the first end cap projection 42 and / or the sixth sealing surface 76 of the second end cap projection 44. Preferably, placing the first housing portion 14 against the second housing portion 16 results in slight compression of the first and / or second filter elements 20, 30, thereby allowing the sealing projections 42, 44 to be securely received in the housing recess 50 (see Figure 1 ).

[0078] Figure 3 The gas filter system 10 from the previous figures is shown in cross-section, the section being oriented perpendicular to the longitudinal axis and extending through the end cap projections 42, 44 and the sealing projection 52. The sealing projection 52 is arranged in the common groove 46 in accordance with the present invention.

[0079] According to this embodiment, the first end cap protrusion 42 and the second end cap protrusion 44 are formed to be circumferentially closed. The two end cap protrusions 42, 44 form a common web 78. As shown in the figure, the common web 78 can be circumferentially closed. Preferably, as shown in the figure, the common web 78 is formed as a ring, in particular with 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 refer to the longitudinal axis 28 of the gas filter system 10.

[0080] As shown in the figure, common groove 46 can be circumferentially closed.Preferably, common groove 46 is formed circumferentially by first end cap protrusion 42 and second end cap protrusion 44.Common groove 46 can have at least one radial protrusion 86 or radial recess 88.Preferably, as shown in the figure, common groove 46 has several radial protrusions 86 and several radial recesses 88, and they are particularly formed on the circumference in a uniformly distributed manner.In other words, common groove 46 can be designed to swing around median radius 90.This realizes that filter element 20,30 is arranged with respect to each other and the anti-torsion in housing 12, and good sealing arrangement can be obtained thus.

[0081] The sealing protrusion 52 may be formed to be complementary to the common groove 46 of the first end cap protrusion 42 and the second end cap protrusion 44. In other words, the sealing protrusion 52 follows the corrugated shape of the common groove 46.

[0082] Reference now Figure 4 , showing a second enlarged cross-sectional view through the radial projection 86 Figure 1 and Figure 2 A first end of the filtration system 10.

[0083] According to the figure, the first end cover protrusion 42 and / or the second end cover protrusion 44 may have a stepped cross section 92, 94 in the axial direction, see also Figure 5 and 6 As shown, the stepped cross-section 92 of the first end cap protrusion 42 may be radially recessed from the first end cap 24. The stepped cross-section 94 of the second end cap protrusion 44 may radially extend relative to the third end cap 34 in a complementary manner. Preferably, the radially extending stepped cross-section 94 overlaps the radially recessed stepped cross-section 92. This allows the end caps 24, 34 to be arranged at a particularly close distance from each other.

[0084] Figure 5 A schematic perspective view shows Figure 1 The outer filter element 20 of the gas filter system 10 is shown in FIG. 1 . The outer filter element 20 includes a support tube 64 , which is a hollow cylindrical shape as shown in the figure.

[0085] According to the embodiment shown, the outer filter element 20 has a plurality of stepped cross sections 92 at the first end cap protrusion 42. The stepped cross sections 92 are radially concave here and are evenly distributed around the inner perimeter of the first end cap 24 having the end cap protrusion 42.

[0086] As shown, the first end cap protrusion 42 may have a non-stepped cross section 96. The non-stepped cross section 96 may be formed alternately with the stepped cross section 92.

[0087] Figure 6 A schematic perspective view shows Figure 1 The internal filter element 30 of the gas filtration system 10 .

[0088] According to the embodiment shown, the outer filter element 30 has a plurality of stepped sections 94 at the second end cap protrusion 44. The stepped sections 94 here extend radially and are evenly distributed around the outer perimeter of the third end cap 34 having the second end cap protrusion 44.

[0089] As shown, the second end cap protrusion 44 may have a non-stepped cross section 98. The non-stepped cross section 98 may be formed alternately with the stepped cross section 94.

[0090] The stepped sections 92, 94 and / or the non-stepped sections 96, 98 are preferably each formed in pairs complementary to each other. When the outer filter element 20 is arranged to surround the inner filter element 30, the stepped sections 92, 94 and / or the non-stepped sections 96, 98 are preferably engaged with each other.

[0091] In summary, the present invention therefore relates to a gas filtration system (10) comprising:

[0092] - a housing (12) having a sealing projection (52) in a housing recess (50);

[0093] - an outer filter element (20) having a first filter medium (22) and a first end cap (24); and

[0094] - an inner filter element (30) having a second filter medium (32) and a third end cap (34);

[0095] The first end cover (24) has a first axial end cover protrusion (42), and the third end cover (34) has a second axial end cover protrusion (44), and both end cover protrusions (42, 44) are arranged in the housing groove (50);

[0096] The first end cap protrusion and the second end cap protrusion (42, 44) form a common groove (46), and the sealing protrusion (52) extends into the common groove (46) for abutting against the first end cap and the third end cap (24, 34) at the common groove (46) to seal. 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).

[0097] List of reference numerals:

[0098] Gas filtration system 10 axial collar 56;

[0099] Housing 12; Housing spacer 58;

[0100] First housing portion 14; Bottom plate 60;

[0101] Second housing portion 16; Filter spacer 62;

[0102] Inlet 18; Support tube 64;

[0103] outlet 19; first sealing surface 66;

[0104] External filter element 20; Second sealing surface 68;

[0105] First filter medium 22; Third sealing surface 70;

[0106] First end cap 24; Fourth sealing surface 72;

[0107] The second end cap 26; The fifth sealing surface 74;

[0108] longitudinal axis 28; sixth sealing surface 76;

[0109] Internal filter element 30; Common web 78;

[0110] Second filter medium 32; width 80;

[0111] The third end cap 34; inner diameter 82;

[0112] Fourth end cap 36; outer diameter 84;

[0113] Cleaning side 40; Radial protrusion 86;

[0114] First end cap protrusion 42; Radial recess 88;

[0115] Second end cap protrusion 44; median radius 90;

[0116] Common groove 46; Stepped cross section 92;

[0117] Shell end face 48; Stepped cross section 94;

[0118] Housing groove 50; non-stepped section 96;

[0119] Sealing protrusion 52; non-stepped cross section 98.

[0120] Central tube 54;

Claims

1. A gas filtration system (10) comprising - a housing (12) having a sealing protrusion (52) and a housing groove (50), wherein the sealing protrusion (52) is arranged in 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); and - 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 end cap and the third end cap (24, 34) are open; The first filter medium (22) can be arranged to surround the second filter medium (32) so that the first end cap (24) of the outer filter element (20) surrounds the third end cap (34) of the inner filter element (30); in, The first end cover (24) has a first axial end cover protrusion (42), and the third end cover (34) has a second axial end cover protrusion (44), and the first axial end cover protrusion (42) and the second axial end cover protrusion (44) are arranged in the housing groove (50); The first end cap protrusion and the second end cap protrusion (42, 44) form a common groove (46), and the sealing protrusion (52) extends into the common groove (46) for abutting against the first end cap and the third end cap (24, 34) at the common groove (46) for sealing.

2. The gas filtration system (10) according to 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) for abutting and sealing against a sealing projection (52) of the housing (12), preferably in a radial direction.

3. The gas filtration system (10) according to 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) for abutting and sealing against a sealing projection (52) of the housing (12), preferably in a radial direction.

4. The gas filtration system (10) according to any one of the preceding claims, wherein: The common groove (46) extends along the inner circumference of the first end cover (24) and / or along the outer circumference of the third end cover (34).

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

6. The gas filtration system (10) according to claim 5, wherein: The common groove (46) has a plurality of radial protrusions (86) and radial recesses (88), and the protrusions (86) and recesses (88) are formed on the circumference in a uniformly distributed manner.

7. A gas filtration system (10) according to any one of the preceding claims, wherein: The first end cap protrusion (42) and the second end cap protrusion (44) form a common web (78) including a common groove (46).

8. The gas filtration system (10) according to claim 7, wherein: The common web (78) is formed as a circular or elliptical ring having a constant width (80).

9. A gas filtration system (10) according to any one of the preceding claims, wherein: The first end cap (24) and / or the third end cap (34) are integral foam parts.

10. The gas filtration system (10) according to any one of the preceding claims, wherein: The sealing protrusion (52) is formed to complement the common groove (46) of the first end cover protrusion (42) and the second end cover protrusion (44).

11. The gas filtration system (10) according to any one of the preceding claims, wherein: The housing groove (50) is adapted to press the first and second end cover protrusions (42, 44) against the sealing protrusion (52).

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

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

14. The gas filtration system (10) according to any one of the preceding claims, wherein: The first end cap protrusion (42) has at least one stepped cross-section (92), and the second end cap protrusion (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 the preceding claims.

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) being open, wherein: The first end cap (24) has an axial end cap protrusion (42) disposed on an inner circumference of the first end cap (24) and having a radially inwardly directed sealing surface (66).

17. The gas filter element (20) according to claim 16, wherein: The sealing surface (66) of the end cap protrusion (42) includes 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) being open, wherein: The third end cap (34) has an axial end cap protrusion (44) which is arranged on the outer circumference of the third end cap (34) and has a sealing surface (68) directed radially outward.

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

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