Filter system with a secondary filter element and a primary filter element, and use of a secondary filter element in a filter system

Abstract

The invention relates to a filter system (100) with a housing (110) which has a fluid inlet (112) and a fluid outlet (114), wherein at least one primary filter element (10) and one secondary filter element (40) are arranged in the housing (110) between the fluid inlet (112) and the fluid outlet (114), wherein the primary filter element (10) and the secondary filter element (40) can be flowed through at least temporarily one after another by a fluid to be filtered, in particular a gaseous fluid, in particular air. At the fluid outlet (114), the housing (110) has at least one coupling element (120) for coupling to a coupling means (70) which is arranged on the secondary filter element (40). The filter medium body (60) of the secondary filter element (40) has an adsorbent, in particular activated carbon. The coupling means (70) is designed to be coupled to the primary filter element (10) such that it cannot rotate. The invention also relates to a use of a secondary filter element (40) in a filter system (100).

Description

[0001] Filter system with a secondary filter element and a primary filter element and use of a secondary filter element in a filter system

[0002] Technical area

[0003] The invention relates to a filter system with a secondary filter element and a primary filter element, in particular for the filtration of a gaseous fluid, in particular air, as well as the use of a secondary filter element in a filter system.

[0004] State of the art

[0005] Filter systems with a primary filter element and a secondary filter element downstream of the filter are common, for example, in air filter systems. The secondary filter element serves as a safety element to protect the clean side of the filter system, for example, when changing the primary filter element.

[0006] Disclosure of the invention

[0007] An object of the invention is to provide an improved filter system with a secondary filter element and a primary filter element.

[0008] Another object of the invention is to provide a use of a secondary filter element in an improved filter system.

[0009] The above-mentioned objects are achieved according to one aspect of the invention with a filter system having a housing which has a fluid inlet and a fluid outlet, wherein at least one primary filter element and one secondary filter element are arranged in the housing between the fluid inlet and the fluid outlet, wherein the secondary filter element is arranged in a hollow interior of the primary filter element, and wherein the primary filter element and the secondary filter element can be flowed through at least twice in succession by a fluid to be filtered, in particular a gaseous fluid, in particular air, wherein the housing has at least one coupling element at the fluid outlet for coupling to a coupling device arranged on the secondary filter element, wherein the secondary filter element has a filter medium body permeable to the fluid to be filtered,which extends along a longitudinal axis and surrounds a hollow interior space and which has an open end and a closed end opposite along the longitudinal axis, wherein the filter medium body of the secondary filter element comprises an adsorbent, in particular activated carbon, wherein the coupling device is arranged at an open end of the filter medium body of the secondary filter element, characterized in that the coupling device is designed for twisted coupling to the primary filter element, and in that the at least one coupling element of the housing is designed as a thread and complementary to a thread of the coupling element of the secondary filter element, wherein the thread of the coupling element of the secondary filter element can be brought into engagement with the thread of the coupling element of the housing. The objects are achieved according to a further aspect of the invention by using a secondary filter element in a filter system,wherein the secondary filter element comprises a filter medium body permeable to the fluid to be filtered, which extends along a longitudinal axis and surrounds a hollow interior space and which has an open end and a closed end opposite along the longitudinal axis, and wherein the filter medium body of the secondary filter element comprises an adsorbent, in particular activated carbon, wherein the secondary filter element is arranged in a hollow interior space of the primary filter element of the filter system, and wherein the primary filter element and the secondary filter element are flowed through at least twice in succession by a fluid to be filtered, in particular a gaseous fluid, in particular air, during operation of the filter system, wherein the housing of the filter system has at least one coupling element at the fluid outlet for coupling to a coupling device arranged on the secondary filter element,wherein the coupling device is arranged at an open end of the filter medium body of the secondary filter element, wherein the secondary filter element is coupled to the primary filter element by means of the coupling device, and a thread of the coupling element of the secondary filter element is engaged with the coupling element of the housing, which is designed as a thread.

[0010] Advantageous embodiments and advantages of the invention emerge from the further claims, the description and the drawing.

[0011] According to one aspect, the invention is based on a filter system with a housing having a fluid inlet and a fluid outlet, wherein at least one primary filter element and one secondary filter element are arranged in the housing between the fluid inlet and the fluid outlet, wherein the secondary filter element is arranged in a hollow interior of the primary filter element, and wherein a fluid to be filtered, in particular a gaseous fluid, in particular air, can flow through the primary filter element and the secondary filter element at least twice in succession. The housing has at least one coupling element at the fluid outlet for coupling to a coupling device arranged on the secondary filter element.The secondary filter element comprises a filter medium body permeable to the fluid to be filtered, which extends along a longitudinal axis and surrounds a hollow interior, and which has an open end and a closed end opposite the longitudinal axis. The filter medium body of the secondary filter element comprises an adsorbent, in particular activated carbon. The coupling device is arranged at an open end of the filter medium body of the secondary filter element.

[0012] According to the invention, the coupling device is designed for a twisted coupling to the primary filter element. The at least one coupling element of the housing is designed as a thread and complements a thread of the coupling element of the secondary filter element. The thread of the coupling element of the secondary filter element can be brought into engagement with the thread of the coupling element of the housing. The secondary filter element is arranged downstream of the primary filter element in terms of flow and can provide additional protection for the clean side, for example, when the primary filter element is replaced or against substances that the primary filter element does not retain. Advantageously, the primary filter element and secondary filter element can be replaced independently of one another.This allows for a different loading of the primary filter element and the secondary filter element to be taken into account, so that an unnecessary change of the primary filter element or the secondary filter element can be avoided.

[0013] Advantageously, the secondary filter element can have an interface for coupling to the primary filter element and an interface for coupling to the housing of the filter system. This allows the secondary filter element to be installed in the housing in a rotationally fixed manner, even when subjected to significant mechanical stress and vibration during operation.

[0014] Because the filter medium body contains an adsorbent, harmful gases that pass through the primary filter element can be largely removed from the fluid in the secondary filter element. This is particularly advantageous when the filter system is used in systems with components that are sensitive to harmful gases. The filter system with the secondary filter element is particularly advantageous in fuel cell systems to filter the cathode supply air. Harmful gases can degrade or even destroy the membranes between the cathodes and anodes of the fuel cells.

[0015] Advantageously, the coupling element can be sleeve-shaped and have an interface for coupling to the secondary filter element and a separate interface for coupling to the housing. Advantageously, the coupling to the primary filter element can be designed to be twist-resistant. This can further improve the operational reliability of the filter system with a secondary filter element.

[0016] The secondary filter element can be coupled to the filter housing via a thread, for example, which makes it particularly easy to upgrade the functionality of existing filter systems with conventional secondary filter elements that lack gas adsorption functionality. The non-rotatable coupling between the primary filter element and the secondary filter element can advantageously be used to screw the secondary filter element into or out of the housing-side thread indirectly via the primary filter element.

[0017] Advantageously, the at least one coupling element can be designed as a thread complementary to an external thread of a threaded connector of the coupling element. This allows for an advantageous, non-rotatable connection between the secondary filter element and the housing. Alternatively, a simple plug-in connection can also be provided.

[0018] According to a favorable embodiment of the filter system, the primary filter element can comprise a filter medium body permeable to the fluid to be filtered, which extends along a longitudinal axis and surrounds a hollow interior, and which has an open end and a closed end opposite the longitudinal axis. The filter medium body of the primary filter element can have at least one coupling element at its open end for twisted coupling to the coupling device of the secondary filter element.

[0019] During operation, the secondary filter element can be arranged in the hollow interior of the primary filter element. The interface, i.e., the coupling element and coupling device, between the primary filter element and the secondary filter element is arranged at the open end of the primary filter element and the secondary filter element, respectively. Advantageously, a polyurethane (PUR) ring can be arranged at the open end of the primary filter element.

[0020] According to a favorable embodiment of the filter system, the coupling device of the secondary filter element can comprise a socket having the thread at the open end of the filter medium body of the secondary filter element. In particular, the thread can be an external thread. In particular, the socket can alternatively or additionally protrude beyond the open end of the filter medium body of the secondary filter element.

[0021] Advantageously, a sealing surface for a sealing element can be arranged on the nozzle of the coupling device, so that the clean side inside the secondary filter element is sealed against the raw side of the filter element.

[0022] Conveniently, this interface for coupling to the housing can be arranged on the sleeve-shaped coupling device at an axial distance from the interface to the primary filter element. The coupling element can be screwed with the external thread into a complementary thread of the housing, in particular at an outlet connection for the filtered fluid. The secondary filter element can thus be stably connected, in particular in a rotationally fixed manner, to the housing. Alternatively, it is possible for the secondary filter element to be inserted into the housing, in particular into the outlet connection for the filtered fluid. In this case, a thread can be omitted.

[0023] According to a favorable embodiment of the filter system, the coupling device can have axially extending ribs on a particularly outer circumferential surface, which can be inclined toward the longitudinal axis, particularly in the direction of the closed end of the filter medium body of the secondary filter element. The ribs can advantageously prevent relative rotation between the primary filter element and the secondary filter element.

[0024] Alternatively or additionally, the coupling device can have axial recesses, particularly on an outer circumferential surface. The axial recesses can advantageously be designed to complement the shape of projections on the inner circumference of the primary filter element. According to a favorable embodiment of the filter system, the ribs and / or recesses can be arranged adjacent to an outer circumferential surface of the filter medium body of the secondary filter element and / or overlap the filter medium body of the secondary filter element with respect to the longitudinal axis.

[0025] According to a favorable embodiment of the filter system, the coupling element of the secondary filter element can have a groove into which the filter medium body is immersed. Advantageously, the groove can be located on the outer surface of the coupling element.

[0026] According to a favorable design of the filter system, the ribs can be located on the outside of an outer groove wall. This allows the primary filter element, for example, with an open elastic end plate, to be easily slid axially over the groove wall. Alternatively or additionally, the axial recesses can be located on the outside of an outer groove wall.

[0027] According to a favorable embodiment of the filter system, the at least one coupling element of the primary filter element can have at least one projection that projects into the interior with a radial component and is designed to engage with at least one of the axially extending ribs of the coupling device of the secondary filter element in order to achieve the most torsion-resistant coupling of the coupling element of the primary filter element with the coupling device of the secondary filter element. The projection on the inner circumference of the primary filter element can engage in the axial recesses on the coupling device of the secondary filter element and further improve the rotationally fixed coupling.

[0028] The at least one coupling element of the primary filter element can be designed to complement at least one axial recess on the coupling device of the secondary filter element. During assembly, the at least one projection can be inserted into the axial recess of the coupling device of the secondary filter element. If the coupling device of the secondary filter element has outwardly facing ribs, a favorable, rotationally fixed connection can be created. The at least one projection can advantageously be made of PUR.

[0029] According to a favorable embodiment of the filter system, the coupling element of the primary filter element can have at least two projections, each of which projects into the interior with a radial component and is spaced apart in a circumferential direction. Advantageously, several projections can be arranged equidistant from one another, for example, and can engage in corresponding axial recesses of the secondary filter element. In particular, the coupling element of the primary filter element can be designed to complement the shape of at least one axial recess of the coupling device of the secondary filter element. The projections on the inner circumference of the primary filter element can engage in the axial recesses on the coupling device of the secondary filter element, further improving the rotationally fixed coupling.According to a favorable embodiment of the filter system, the filter medium body of the secondary filter element can comprise a pleated filter medium with an adsorbent. Alternatively, the filter medium body of the secondary filter element can comprise a wound filter medium with an adsorbent. For example, the adsorbent, preferably activated carbon, can be introduced and fixed between two nonwoven layers, which are then wound or folded. Optionally, the adsorbent can also be present as a loose fill between the nonwoven layers.

[0030] According to a favorable embodiment of the filter system, the filter medium body of the secondary filter element can have a reinforcing element, in particular a grid, on its outer and / or inner side. This advantageously allows horizontal installation of the filter element. The reinforcing element can advantageously protect the surface of the secondary filter element from damage if the primary filter element is removed from the secondary filter element, for example, when replacing the primary filter element.

[0031] According to a favorable embodiment of the filter system, an end plate can be arranged at the closed end of the filter medium body of the secondary filter element, which end plate can, in particular, have a recess as an assembly aid. The recess can serve to position a corresponding tool for unscrewing the secondary filter element from the housing or screwing it into the housing.

[0032] According to a favorable design of the filter system, the housing can have a particle outlet. Particles, such as dust, that are separated from the primary filter element can be collected and removed through the particle outlet.

[0033] According to a favorable design of the filter system, the outlet nozzle can have a closure element that opens and closes depending on the weight. The closure element can advantageously be designed as a pivoting flap. As soon as a certain amount of particles has accumulated on the flap, the flap opens automatically, allowing the particles to fall out of the outlet nozzle. Once the weight is no longer applied to the flap, it can close again. Alternatively, the closure element can also be designed as a valve.

[0034] According to a further aspect of the invention, the use of a secondary filter element in a filter system is proposed, wherein the secondary filter element has a filter medium body permeable to the fluid to be filtered, which extends along a longitudinal axis and surrounds a hollow interior and which has an open end and a closed end opposite along the longitudinal axis. The filter medium body of the secondary filter element has an adsorbent, in particular activated carbon. The secondary filter element is arranged in a hollow interior of a primary filter element of the filter system, and a fluid to be filtered, in particular a gaseous fluid, in particular air, flows through the primary filter element and the secondary filter element at least twice in succession during operation of the filter system.The housing of the filter system has at least one coupling element at the fluid outlet for coupling to a coupling device arranged on the secondary filter element, wherein the coupling device is arranged at an open end of the filter medium body of the secondary filter element. The secondary filter element is coupled to the primary filter element by means of the coupling device, and a thread of the coupling element of the secondary filter element is brought into engagement with the threaded coupling element of the housing.

[0035] The secondary filter element is located downstream of the primary filter element and can provide additional protection for the clean side, for example, when the primary filter element is replaced or against substances that the primary filter element cannot retain. Advantageously, the primary filter element and secondary filter element can be replaced independently of each other. This allows for different loadings of the primary filter element and secondary filter element to be taken into account, thus avoiding unnecessary replacement of the primary filter element or secondary filter element.

[0036] Advantageously, the secondary filter element can have an interface for coupling to the primary filter element and an interface for coupling to the housing of the filter system. This allows the secondary filter element to be installed in the housing in a rotationally fixed manner, even when subjected to significant mechanical stress and vibration during operation.

[0037] Because the filter medium body contains an adsorbent, harmful gases that pass through the primary filter element can be largely removed from the fluid in the secondary filter element. This is particularly advantageous when the filter system is used in systems with components that are sensitive to harmful gases. The filter system with the secondary filter element is particularly advantageous in fuel cell systems to filter the cathode supply air. Harmful gases can degrade or even destroy the membranes between the cathodes and anodes of the fuel cells.

[0038] Advantageously, the coupling element can be sleeve-shaped and have an interface for coupling to the secondary filter element and a separate interface for coupling to the housing. Advantageously, the coupling to the primary filter element can be designed to be twist-resistant. This can further improve the operational reliability of the filter system with a secondary filter element.

[0039] The secondary filter element can be coupled to the filter housing, for example, via a thread, which makes it possible, in particular, to easily upgrade the functionality of existing filter systems with a conventional secondary filter element that do not have gas adsorption functionality.

[0040] Advantageously, the at least one coupling element can be designed as a thread complementary to an external thread of a threaded connector of the coupling element. This allows for an advantageously rotationally fixed connection between the secondary filter element and the housing. Alternatively, a simple plug-in connection can also be provided. According to a favorable embodiment, the thread of the coupling element of the secondary filter element can be brought into engagement with the coupling element of the housing, which is designed as a thread, by rotating the primary filter element, wherein a rotational movement of the primary filter element can be transmitted to the coupling device of the secondary filter element via the rotationally fixed coupling of the coupling device of the secondary filter element with the primary filter element.

[0041] The rotationally fixed coupling between the primary filter element and the secondary filter element can advantageously be used to screw the secondary filter element in or out of the housing-side thread indirectly via the primary filter element.

[0042] Short description of the drawings

[0043] Further advantages will 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. Those skilled in the art will expediently consider the features individually and combine them into useful further combinations. The following are examples: Figure 1 shows an isometric view of a housing of a filter system according to an exemplary embodiment of the invention;

[0044] Figure 2 shows a sectional view of the filter system according to Figure 1 with interfaces;

[0045] Figure 3 shows a sectional view of an embodiment of the housing of the filter system according to Figure 1;

[0046] Figure 4 shows a detailed view of the interfaces between the primary filter element, secondary filter element and housing of the filter system from Figure 2;

[0047] Figure 5 is an isometric view of a secondary filter element according to an embodiment of the invention;

[0048] Figure 6 is a further isometric view of the secondary filter element from Figure 5;

[0049] Figure 7 is an isometric view of a primary filter element according to an embodiment of the invention;

[0050] Figure 8 shows another isometric view of the primary filter element from Figure 7.

[0051] Embodiments of the invention

[0052] In the figures, identical or similar components are numbered with the same reference numerals. The figures show only examples and are not to be understood as limiting.

[0053] To explain the invention, Figures 1 to 4 show a filter system 100 according to an embodiment of the invention, wherein Figure 1 shows an isometric view of the housing 110 of the filter system, and Figure 2 shows a sectional view through the filter system 100 according to Figure 1 with interfaces between a secondary filter element 40 and a primary filter element 10, and the secondary filter element 40 and the housing 110. Figure 3 shows a detail of an outlet nozzle 140 for discharging particles from the housing 110. The primary filter element 10 is arranged in the housing 110, and the secondary filter element 40 is arranged in the hollow interior 26 of the housing. If the primary filter element 10 is removed from the housing, the secondary filter element 40 protects the raw side of the filter system 100.

[0054] The housing 110 has a fluid inlet 112 and a fluid outlet 114, between which the primary filter element 10 and the secondary filter element 40 are arranged in the flow direction of the fluid to be filtered, for example air, during normal operation.

[0055] In this example, the fluid inlet 112 is arranged tangentially, so that the fluid enters the housing 110 tangentially, allowing pre-separation of particles, such as dust, to occur. The primary filter element 10 advantageously has a circumferential frame 16 in the area of ​​the fluid inlet 112 as an inflow protection.

[0056] In this example, the fluid outlet 114 is arranged centrally and leads the filtered fluid out of the filter system 100 via a nozzle 118.

[0057] In this example, the housing 110 is arranged such that the primary filter element 10 and the secondary filter element 40 are arranged horizontally. This is a common installation situation, for example, in cathode air filter systems of fuel cells. In the lower region of the housing 110, a collecting chamber 130 for particles is arranged (Figure 3), which can be discharged via an outlet nozzle 140. For this purpose, a closure device 150 in the form of a cap is pushed over the outlet nozzle 140. This closure device 150 has a flap as the closure element 152, which opens depending on the weight and closes again after the collecting chamber 130 has been emptied, for example via spring force. If the intended installation position of the filter system 100 deviates from the intended installation position, the position of the outlet nozzle 140 can be suitably selected accordingly.

[0058] Figure 4 shows a detailed view of the interfaces between primary filter element 10, secondary filter element 40 and housing 110 of the filter system 100 from Figure 2. Figures 5 and 6 show various views of the secondary filter element 40 according to an embodiment of the invention and Figures 7 and 8 show various views of the primary filter element 10 according to an embodiment of the invention, each in isometric representation.

[0059] The fluid outlet 114 has a coupling element 120 for coupling to a coupling device 70 arranged on the secondary filter element 40. In this example (Figure 4), the coupling element 120 is formed as a thread 122 on the inner circumference of the fluid outlet 114, complementary to an external thread 73 of a threaded connector 72 of the coupling element 70.

[0060] The secondary filter element 40 comprises a filter medium body 60 permeable to a fluid to be filtered, in particular a gaseous fluid, in particular air, which extends along a longitudinal axis 200 and surrounds a hollow interior space 64, and which has an open end 42 and a closed end 44 opposite the longitudinal axis 200 (Figures 5 and 6). The filter medium body 60 comprises an adsorbent, in particular activated carbon.

[0061] The filter medium body 60 can comprise a pleated filter medium with adsorbent or a wound filter medium with adsorbent. The filter medium body 60 can expediently surround a support tube 90. The filter medium body 60 can advantageously have a reinforcing element 62 on its outer shell, which can be designed, for example, as a grid. This can be seen in the detailed view in Figure 4 and is symbolically indicated as a section in Figure 5. Of course, the outer shell can be completely surrounded by the reinforcing element 62. The reinforcing element 62 protects the filter medium body 60 from damage, for example during an element change. Alternatively, the reinforcing element 62 can be present on the inside of the filter medium body 60.

[0062] An end plate 50 is arranged at the closed end 44 of the filter medium body 60. It has a recess 54 with radial cutouts as an assembly aid. A suitable tool for assembling and disassembling the secondary filter element 40 can be positioned there, if necessary.

[0063] The coupling device 70 is arranged at the open end 42 of the filter medium body 60 and has interfaces to the housing 110 on the one hand and to the primary filter element 10 on the other. These interfaces are expediently located on the outside of the coupling device 70.

[0064] The coupling device 70 is sleeve-shaped. The filter medium body 60 of the secondary filter element 40, together with the support tube 90, extends into a circumferential groove 76 of the coupling element 70 and is, for example, glued or cast there. On an outer side of the outer groove wall 78 of the groove 76, the coupling device 70 has axial recesses 80. The outer side of the outer groove wall 78 also has axially extending ribs 82 that are inclined toward the closed end 44 toward the longitudinal axis 200. The outer groove wall 78, in particular the axial recesses 80 therein, form the interface to the primary filter element 10, as can be seen in Figure 4. The primary filter element 10 can be inserted over the outer side of the groove wall 78.

[0065] The axial recesses 80 on the coupling device 70 of the secondary filter element 40 and the corresponding projections 24 on the primary filter element 10 have the further advantage that they enable coding of the primary filter element 10 and the secondary filter element 40.

[0066] The primary filter element 10 comprises a filter medium body 20 permeable to a fluid to be filtered, in particular a gaseous fluid, in particular air, which extends along a longitudinal axis 200 and surrounds a hollow interior 26 and which has an open end 12 and a closed end 14 opposite along the longitudinal axis 200 (Figures 7 and 8). At the open end 12, the primary filter element 10 has an open end plate 34, in particular made of PUR. At the closed end 14, a closed end plate 30 or a cover or the like is arranged. The filter medium body 20 of the primary filter element 10 has, at its open end 12, a plurality of coupling elements 38 circumferentially extending around its inner circumference for coupling to the coupling device 70 of the secondary filter element 40.

[0067] The coupling elements 38 are designed as projections 24 that protrude into the interior space 26 and are complementary in shape to the axial recesses 80 on the coupling device 70 of the secondary filter element 40. The coupling elements 38 are preferably an integral part of the open end plate 34. Recesses 22 are arranged circumferentially on the outer circumference of the open end plate 34.

[0068] If the primary filter element 10 is pushed over the coupling device 70 of the secondary filter element 40, the ribs 82 on the outer side of the groove wall 78 of the coupling device 70 dig into the relatively elastic material of the open end plate 34 and form a rotationally fixed connection to the coupling device 70. The recesses on the outer circumference of the open end plate 34 further support the stability against unwanted twisting during operation of the filter element 100.

[0069] The filter medium body 20 of the primary filter element 10 can be wound or star-folded and have stabilizing thread windings on its outer circumference, which can be seen in Figures 7 and 8 above the frame 16.

[0070] On the closed end plate 30, which can also preferably be made of PUR, spacers 32 projecting in the axial direction are arranged.

[0071] Furthermore, the coupling device 70 of the secondary filter element 40 has a threaded connector 72 at the open end 42 of the filter medium body 60 of the secondary filter element 40 for coupling to the housing 110 of the filter system 100. The threaded connector 72 extends away from the groove 76 in the direction of the longitudinal axis 200. An external thread 73 is formed on the threaded connector 72, which can be seen particularly in Figures 4 and 5. This allows the secondary filter element 40 to be screwed into or unscrewed from the connector 118 of the fluid outlet 114. This also improves the non-rotatable arrangement of the secondary filter element 40 during operation of the filter system 100.

[0072] In this way, the secondary filter element 40 can advantageously be coupled directly to the filter housing 110 via the thread 73, which in particular makes it possible to easily upgrade the functionality of existing filter systems with conventional secondary filter elements that do not have gas adsorption functionality. The rotationally fixed coupling between the primary filter element 10 and the secondary filter element 40 can advantageously be used to screw the secondary filter element 40 into or out of the housing-side thread 122 indirectly via the primary filter element 10.

[0073] Alternatively, a simple plug-in design without a thread is also possible (not shown). As can be seen in Figure 4, a sealing ring 74 is arranged between the thread 73 on the threaded connector 72 and the groove 76 of the coupling device 70 of the secondary filter element 40, which enables a seal between the clean side and the dirty side of the filter system 100, particularly if the primary filter element 10 is removed from the secondary filter element 40.

[0074] Reference symbol

[0075] 10 Primary filter element

[0076] 12 open ending

[0077] 14 closed end

[0078] 16 frame

[0079] 20 filter medium bodies

[0080] 22 Deepening

[0081] 24 lead

[0082] 26 Interior

[0083] 30 closed end plate

[0084] 32 Support element

[0085] 34 open end plate

[0086] 36 Seal

[0087] 38 coupling element

[0088] 40 Secondary filter element

[0089] 42 open ending

[0090] 44 closed end

[0091] 50 end plate

[0092] 52 notch

[0093] 54 Deepening

[0094] 60 filter medium bodies

[0095] 62 Reinforcing element

[0096] 64 Interior

[0097] 70 Coupling device

[0098] 72 threaded connectors

[0099] 73 threads

[0100] 74 Sealing ring

[0101] 76 grooves

[0102] 78 outer groove wall

[0103] 80 deepening

[0104] 82 rib

[0105] 90 support tube

[0106] 100 filter system

[0107] 110 housings

[0108] 112 Fluid inlet

[0109] 114 Fluid outlet

[0110] 118 nozzles

[0111] 120 coupling element

[0112] 122 threads

[0113] 130 assembly room

[0114] 140 outlet nozzles

[0115] 150 locking device

[0116] 152 locking element

[0117] 200 Longitudinal axis

Claims

Claims 1. Filter system (100) with a housing (110) having a fluid inlet (112) and a fluid outlet (114), wherein at least one primary filter element (10) and one secondary filter element (40) are arranged in the housing (110) between the fluid inlet (112) and the fluid outlet (114), wherein the secondary filter element (40) is arranged in a hollow interior (26) of the primary filter element (10), and wherein the primary filter element (10) and the secondary filter element (40) can be flowed through at least twice in succession by a fluid to be filtered, in particular a gaseous fluid, in particular air, wherein the housing (110) has at least one coupling element (120) at the fluid outlet (114) for coupling to a coupling device (70) arranged on the secondary filter element (40), wherein the secondary filter element (40) has a filter medium body (60),which extends along a longitudinal axis (200) and surrounds a hollow interior (64) and which has an open end (42) and a closed end (44) opposite along the longitudinal axis (200), wherein the filter medium body (60) of the secondary filter element (40) has an adsorbent, in particular activated carbon, wherein the coupling device (70) is arranged at an open end (42) of the filter medium body (60) of the secondary filter element (40), characterized in that the coupling device (70) is designed for twisted coupling to the primary filter element (10), and that the at least one coupling element (120) of the housing (110) is designed as a thread (122) and complementary to a thread (73) of the coupling element (70) of the secondary filter element (40), wherein the thread (73) of the coupling element (70) of the secondary filter element (40) can be brought into engagement with the thread (122) of the coupling element (120) of the housing (110)., 2. Filter system according to claim 1, wherein the primary filter element (10) comprises a filter medium body (20) which is permeable to the fluid to be filtered and which extends along a longitudinal axis (200) and surrounds the hollow interior (26) and which has an open end (12) and a closed end (14) opposite along the longitudinal axis (200), wherein the filter medium body (20) of the primary filter element (10) has at least one coupling element (38) at its open end (12) for twisted coupling to the coupling device (70) of the secondary filter element (40).

3. Filter system according to claim 1 or 2, wherein the coupling device (70) of the secondary filter element (40) at the open end (42) of the filter medium body (60) of the secondary filter element (40) comprises a socket (72) which has the thread (73), in particular wherein the thread (73) is an external thread and / or wherein the socket (72) projects beyond the open end (42) of the filter medium body (60) of the secondary filter element (40).

4. Filter system according to claim 3, wherein the coupling device (70) has, in particular on an outer lateral surface, axially extending ribs (82) which are inclined in particular in the direction of the closed end (44) of the filter medium body (60) of the secondary filter element (40) towards the longitudinal axis (200), and / or wherein the coupling device (70) has, in particular on an outer lateral surface, axial recesses (80).

5. Filter system according to claim 4, wherein the ribs (82) and / or depressions (80) are arranged adjacent to an outer circumferential surface of the filter medium body (60) of the secondary filter element (40) and / or overlap the filter medium body (60) of the secondary filter element (40) with respect to the longitudinal axis (200).

6. Filter system according to one of the preceding claims, wherein the coupling element (70) of the secondary filter element (40) has a groove (76) into which the filter medium body (60) is immersed.

7. Filter system according to claim 6, wherein the ribs (82) are present on an outer side of an outer groove wall (78) of the groove (76) and / or the axial recesses (80) are present on an outer side of an outer groove wall (78) of the groove (76).

8. Filter system according to one of claims 4 to 7, wherein the at least one coupling element (38) of the primary filter element (10) has at least one projection (24) which projects with a radial component into the interior (26) and is designed to bear against at least one of the axially extending ribs (82) of the coupling device (70) of the secondary filter element (40) in order to effect the most twisted coupling of the coupling element (38) of the primary filter element (10) with the coupling device (70) of the secondary filter element (40).

9. Filter system according to claim 8, wherein the coupling element (38) of the primary filter element (10) has at least two projections (24), each of which projects with a radial component into the interior (26) and is spaced apart in a circumferential direction, in particular wherein the coupling element (38) of the primary filter element (10) is designed to be complementary in shape to at least one axial recess (80) of the coupling device (70) of the secondary filter element (40).

10. Filter system according to one of the preceding claims, wherein the filter medium body (60) of the secondary filter element (40) comprises a pleated filter medium with adsorbent, or wherein the filter medium body (60) of the secondary filter element (40) comprises a wound filter medium with adsorbent.

11. Filter system according to one of the preceding claims, wherein the filter medium body (60) of the secondary filter element (40) has a reinforcing element (62), in particular a grid, on its outer and / or inner side.

12. Filter system according to one of the preceding claims, wherein an end plate (50) is arranged at the closed end (44) of the filter medium body (60) of the secondary filter element (40), in particular wherein the end plate (50) has a recess (54) as an assembly aid.

13. Filter system according to one of the preceding claims, wherein the housing (110) has an outlet nozzle (140) for particles.

14. Filter system according to claim 13, wherein the outlet nozzle (140) has a closure element (150) which opens and closes depending on the weight, in particular wherein the closure element (150) is designed as a pivotable flap or valve.

15. Use of a secondary filter element (40) in a filter system (100) according to one of the preceding claims, wherein the secondary filter element (40) has a filter medium body (60) permeable to the fluid to be filtered, which extends along a longitudinal axis (200) and surrounds a hollow interior (64) and which has an open end (42) and a closed end (44) opposite along the longitudinal axis (200), and wherein the filter medium body (60) of the secondary filter element (40) has an adsorbent, in particular activated carbon, wherein the secondary filter element (40) is arranged in a hollow interior (26) of a primary filter element (10) of the filter system (100), and wherein the primary filter element (10) and the secondary filter element (40) are flowed through at least in succession by a fluid to be filtered, in particular a gaseous fluid, in particular air, during operation of the filter system (100).wherein the housing (110) of the filter system (100) has at least one coupling element (120) at the fluid outlet (114) for coupling to a coupling device (70) arranged on the secondary filter element (40), wherein the coupling device (70) is arranged at an open end (42) of the filter medium body (60) of the secondary filter element (40), wherein the secondary filter element (40) is coupled to the primary filter element (10) by means of the coupling device (70) in a twisted manner, and a thread (73) of the coupling element (70) of the secondary filter element (40) is engaged with the coupling element (120) of the housing (110) designed as a thread (122).

16. Use according to claim 15, wherein the thread (73) of the coupling element (70) of the secondary filter element (40) is brought into engagement with the coupling element (120) of the housing (110) designed as a thread (122) by rotating the primary filter element (10), wherein a rotational movement of the primary filter element (10) is transmitted to the coupling device (70) of the secondary filter element (40) via the twisted coupling of the coupling device (70) of the secondary filter element (40) with the primary filter element (10).

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