Gas filtration system

Abstract

The invention relates to a gas filtration system (10) comprising an outer filter element (20) having a first filter medium (22) arranged between a first end cap (24) and a second end cap (26); and an inner filter element (30) having a second filter medium (32) arranged between the third end cap (34) and the fourth end cap (36); the first filter medium (22) may be arranged around the second filter medium (32), where the first end cap (24), the third end cap (34) and the fourth end cap (36) are open, where the outer filter element (20) is closed at the second end cap (26), where the outer filter element (20) has an axial projection (52) at the second end cap (26), and where the outer filter element (20) is closed at the second end cap (26). The fourth end cap (36) of the inner filter element (30) has a first sealing section (52) projecting into the inner filter element (30) and exhibiting a radially outward facing sealing surface (54), and wherein the fourth end cap (36) of the inner filter element (30) has a second sealing section (56) for sealing abutment against the sealing surface (54) of the projection (52).

Description

Technical Field

[0001] The present invention relates to a gas filtering system, comprising:

[0002] - an outer filter element having a first filter medium disposed between a first end cap and a second end cap; and

[0003] - an inner filter element having a second filter medium disposed between a third end cap and a fourth end cap;

[0004] The first filter medium may be arranged to surround the second filter medium. Background Art

[0005] Such a filter system is known from DE 10 2018 215 603 A1.

[0006] In some applications, it is necessary to filter the gas flow with the aid of two filter elements. Typically, the gas flows through a first filter element, and then the pre-filtered gas flows through a second filter element. The filter element can be arranged in a common housing. Such filter systems are, for example, used to filter the combustion air of large combustion engines such as trucks, engineering vehicles, etc. Another application is the air filtration of fuel cells.

[0007] DE 10 2018 215 603A1 discloses a gas filter system having a first filter element surrounding a second filter element. At a first axial end, the open end caps of the two filter elements are associated with a clean air outlet. At a second axial end, the first (external) filter element has an open end cap, and the second (internal) filter element has a closed end cap. The closed end cap of the internal filter element is arranged to close the opening in the end cap of the external filter element at the second axial end.

[0008] The object of the present invention is to provide a gas filter system with an improved seal between two filter elements which are suitable for joint use.

[0009] This is achieved by the use of a gas filter system according to claim 1 and a filter element according to claim 17. Advantageous embodiments are given in the dependent claims and in the description. Summary of the invention

[0010] According to the present invention, a gas filtration system is provided. The gas filtration system comprises

[0011] - an outer filter element having a first filter medium disposed between a first end cap and a second end cap; and

[0012] - an inner filter element having a second filter medium disposed between the third end cap and the fourth end cap.

[0013] The first filter medium may be arranged to surround the second filter medium. The filter medium may be hollow cylindrical or conical, preferably with a substantially circular or oval cross-section. The filter media each surround a longitudinal axis. In particular, the filter media may be arranged concentrically with a common longitudinal axis. Directions such as radial or axial are indicated with reference to the longitudinal axis. In principle, the first end cap and the third end cap are associated with the first axial end; the second end cap and the fourth end cap are associated with the second axial end.

[0014] During use of the gas filtration system, gas flow is typically directed first through the first filter media of the outer filter element and then through the second filter media of the inner filter element.

[0015] According to the present invention, the first end cap, the third end cap and the fourth end cap are open. The first end cap, the third end cap and the fourth end cap generally have a central opening.

[0016] The outer filter element is closed at the second end cap. The second end cap may be an integral closed end cap. Alternatively, a closure device may be permanently attached to the outer filter element for sealing of the second end cap.

[0017] According to the invention, the outer filter element has an axial projection at the second end cap, which projects into the inner filter element when the filter element is arranged for filtering operation of the gas filter system. The projection provides guidance between the filter elements, in particular during installation. The projection typically projects beyond the fourth end cap of the inner filter element in the axial direction.

[0018] Furthermore, according to the invention, the projection exhibits a radially outwardly facing sealing surface. In other words, the radially outwardly facing sealing surface is formed on the projection.

[0019] The fourth end cap of the inner filter element has a (second) sealing section for sealing against the sealing surface of the projection. In this way, the two filter elements are sealed against each other at the second end. Since the second end cap of the outer filter element covering the inner filter element is closed, the filter element, in particular the inner filter element, is also sealed towards the environment, such as the inlet side of the filter system.

[0020] The second sealing section may be an integral part of the fourth end cap. Typically, the second sealing section is made of a softer material than the material of the projection. In particular, the sealing section or the fourth end cap as a whole may be made of polyurethane, preferably polyurethane foam. The projection may be made of rigid plastic.

[0021] Generally speaking, the sealing section described within the context of the present invention is softer than the counterpart it should seal against. In particular, the respective sealing section can be made of polyurethane, preferably polyurethane foam. The respective counterpart can be made of rigid plastic.

[0022] Preferably, the projection is formed integrally with the support tube of the outer filter element. In other words, the support tube closes the second end cap and forms the projection. The support tube reinforces the outer filter element. The support tube may be partially embedded in the second end cap.

[0023] The second end cap may have at least one support leg for axial support of the outer filter element against the housing. The support leg may be made integrally with the second end cap.

[0024] The first end cap of the outer filter element may have a first sealing section for sealing abutment against the housing, preferably in an axial direction.Alternatively or additionally, the first sealing section may provide radial sealing abutment against the housing.

[0025] The third end cap of the inner filter element may have a third sealing section for sealing abutment against the housing, preferably in radial direction.Alternatively or additionally, the third sealing section may provide axial sealing abutment against the housing.

[0026] Preferably, the first end cap of the outer filter element and the third end cap of the inner filter element are sealed against each other. Thus, gas flow from the environment (such as the inlet side) or from between the filter elements into the environment is prevented. This ensures that the gas flows continuously through the two filter elements.

[0027] The first end cap may have a fourth sealing section for sealingly abutting against the third end cap, preferably in a radial direction.

[0028] Alternatively, the third end cap may have a fourth sealing section for sealingly abutting against the first end cap, preferably in a radial direction.

[0029] Preferably, the gas filtration system further comprises a housing in which the internal filter element and the external filter element can be arranged. In an installed state, the filter element is arranged inside the housing. Typically, the housing comprises a first housing portion associated with the first end and a second housing portion associated with the second end. An inlet can be formed at the first housing portion or the second housing portion. Preferably, an outlet is formed at the first housing portion. The outlet can be in fluid communication with the clean side inside the internal filter element.

[0030] 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 guidance for the inner filter element and provides support for the second filter medium.

[0031] The center tube can be held at the axial collar of the housing. This is advantageous for manufacturing the filter housing. A snap fit can be provided between the collar and the center tube.

[0032] The third end cap can be sealed against the collar or the central tube. In particular, the third sealing section of the third end cap can be sealingly adjacent to the collar or the central tube. In this way, the interior of the inner filter element can be conveniently sealed toward the housing.

[0033] It can be arranged that the projection and the central tube overlap each other in the axial direction. In this way, mutual guidance and support between the central tube and the external filter element can be achieved. This can also facilitate the installation of the filter system. In particular, the projection can be engaged in the central tube. In other words, the central tube can surround the projection radially outward.

[0034] Preferably, the housing has a dome which projects into the projection at the second end cap.The dome can provide guidance during installation and, in particular, additional support for the outer filter element during use of the filter system.

[0035] It can also be arranged that the dome and the central tube overlap each other in the axial direction. With this design, undesired movement of the filter element during operation can be effectively reduced. In the event of severe vibrations, the central tube can be supported against the dome via a projection, which is arranged between the central tube and the dome.

[0036] The first filter medium or the second filter medium, in particular the second filter medium of the inner filter element, can have gas adsorption properties and preferably contain activated carbon. Typical harmful gases are SO2, NO x and NH3.

[0037] The first filter medium or the second filter medium, in particular the first filter medium of the outer filter element, can be made of cellulose.

[0038] The first filter medium and / or the second filter medium may be pleated.

[0039] As mentioned above, the invention also relates to the use of an external filter element and / or an internal filter element in a gas filter system according to the invention. The gas filter system can be used for cathode air filtration of a fuel cell in an electric vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] 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 according to the claims. In variations of the invention, the individual features as described above or explained below may be implemented individually or together in any useful combination.

[0041] Figure 1 A first embodiment of a gas filter system according to the invention is shown in a schematic cross-sectional view, the gas filter system comprising an outer filter element, an inner filter element and a housing;

[0042] Figure 2 Shown in a schematic cross-sectional view Figure 1 External filter elements of gas filtration systems;

[0043] Figure 3 Shown in a schematic cross-sectional view Figure 1 Internal filter elements of the gas filtration system;

[0044] Figure 4 Shown in enlarged view Figure 1 a first end of a filtration system;

[0045] Figure 5 Shown in enlarged view Figure 1 a second end of the filtration system;

[0046] Figure 6 A first end portion of a second embodiment of a filter system according to the invention is shown in a schematic cross-sectional view;

[0047] Figure 7 A first end portion of a third exemplary embodiment of a filter system according to the invention is shown in a schematic sectional view. DETAILED DESCRIPTION

[0048] Figure 1 A 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 18 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.

[0049] The filter system 10 also includes an external filter element 20, see also Figure 2 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 a circular manner. The first filter medium 22 may be made of pleated cellulose paper.

[0050] The filter system 10 also includes an internal filter element 30, see also Figure 3The 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 circularly surrounds the longitudinal axis 28. The second filter media 32 may include activated carbon to achieve gas adsorption properties.

[0051] 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 filter medium 22 and the second filter medium 32 are concentric with each other and with the longitudinal axis 28.

[0052] At the first end of the filter system 10, the first end cap 24 is arranged to surround the third end cap 34, see also Figure 4 The first end cap 24 and the third end cap 34 each have a central opening, see also Figure 2 and Figure 3 The outlet 19 is in fluid communication with the clean side 40 within the inner filter element 30, see Figure 1 .

[0053] The first sealing section 42 protrudes axially from the first end cap 24. The first sealing section 42 sealingly adjoins the first housing part 14 in the axial direction. Here, the first end cap 24 and the first sealing section 42 are made integrally from polyurethane foam.

[0054] A third sealing section 44 protrudes axially from the third end cap 34. The third sealing section 44 sealingly abuts the first housing part 14 in the radial direction. In particular, the third sealing section sealingly rests against a collar 46 which protrudes axially into the housing 12 at the outlet 19. Here, the third end cap 34 and the third sealing section 44 are made integrally from polyurethane foam.

[0055] A center tube 48 of the housing 12 is retained at the axial collar 46. The center tube 48 extends through an opening of the third end cap 34 toward the fourth end cap 36. The center tube 48 may be made of a rigid plastic.

[0056] The outer filter element includes a support tube 50. The support tube extends inside the first filter medium 22 from the first end cap 24 to the second end cap 26. The support tube 50 may be partially embedded in the first end cap 24 and / or the second end cap 26. The support tube 50 may be made of a rigid plastic.

[0057] At the second end, the support tube 50 sealingly closes the outer filter element 20. At the second end cap 26, the support tube 50 forms a closing projection 52, see also Figure 5 The projection 52 extends through the central opening in the fourth end cap 36 of the inner filter element 30 into the clean side of the inner filter element 30 .

[0058] The fourth end cap 36 is sealed against the protrusion 52. At the protrusion 52, a sealing surface 54 facing radially outward is formed. A second sealing section 56 is formed at the opening of the fourth end cap 36. Here, the fourth end cap 36 and the second sealing section 56 are made of polyurethane foam in one piece. The second sealing section 56 sealingly abuts the sealing surface 54 of the protrusion 52 in the radial direction.

[0059] The center tube 48 of the housing 12 and the projection 52 of the outer filter element 20 overlap one another along the longitudinal axis 28. The projection 52 may taper above the sealing surface 54 so as to extend into the center tube 48.

[0060] The housing may have a dome 58. Here, the dome 58 is formed at the second housing portion 16. The dome 58 extends toward the interior of the inner filter element 30. In particular, the dome 58 extends into the protrusion 52 of the outer filter element 20. More specifically, the dome 58 and the center tube 48 overlap each other along the longitudinal axis 28.

[0061] A second embodiment of the gas filtration system 10' (partially shown in FIG. Figure 6 ) corresponds roughly to Figures 1 to 5 and the first embodiment of the gas filtration system 10 described above. The filtration system 10' differs from the gas filtration system 10 in that in the second embodiment the third end cap 34 seals against the center tube 48. The third sealing section 44 sealingly abuts the center tube 48 in the radial direction, here, slightly below the collar 46.

[0062] A third embodiment of the gas filtration system 10" (partially shown in Figure 7 See also Figures 1 to 3 The first embodiment of the gas filtration system 10 is substantially the same.

[0063] In the third embodiment, the first end cap 24 of the outer filter element 20 seals axially and radially against the housing 12. The first housing portion 14 has a circumferential rib 60 against which the first sealing section 42 of the first end cap 24 rests in the radial direction.

[0064] The first end cap 24 of the outer filter element 20 and the third end cap 34 of the inner filter element 30 are sealed against each other. The first end cap 24 also has a fourth sealing section 62. The first end cap 24 is made integrally of polyurethane foam with the first sealing section 42 and the fourth sealing section 62. The third end cap 34 is made of rigid plastic and is glued to the second filter medium 32. The fourth sealing section 62 is sealingly adjacent to the third end cap 34 in the radial direction.

[0065] Reference numerals

[0066] Gas filtration system 10; 10'; 10"

[0067] Housing 12

[0068] First housing part 14

[0069] Second housing part 16

[0070] Entrance 18

[0071] Exit 19

[0072] External filter element 20

[0073] First filter medium 22

[0074] First end cap 24

[0075] Second end cap 26

[0076] Longitudinal axis 28

[0077] Internal filter element 30

[0078] Second filter medium 32

[0079] The third end cap 34

[0080] Fourth end cap 36

[0081] Clean side 40

[0082] First sealing section 42

[0083] The third sealing section 44

[0084] Ring 46

[0085] Center tube 48

[0086] Support tube 50

[0087] Protrusion 52

[0088] Sealing surface 54

[0089] Second sealing section 56

[0090] Dome 58

[0091] Rib 60

[0092] Fourth sealing section 62

Claims

1. A gas filtration system (10; 10'; 10”), which includes - an outer filter element (20) having a first filter medium (22) arranged between a first end cap (24) and a second end cap (26); and - an inner filter element (30) having a second filter medium (32) arranged between a third end cap (34) and a fourth end cap (36); The first filter medium (22) can be arranged to surround the second filter medium (32); in, The first end cap (24), the third end cap (34) and the fourth end cap (36) are open; wherein the outer filter element (20) is closed at the second end cap (26); wherein the outer filter element (20) has an axial protrusion (52) at the second end cap (26), the protrusion (52) protruding into the inner filter element (30) and presenting a sealing surface (54) facing radially outward; And wherein the fourth end cap (36) of the inner filter element (30) has a second sealing section (56) for sealingly abutting against the sealing surface (54) of the projection (52).

2. The gas filtration system (10; 10'; 10") according to claim 1, wherein: The projection (52) is formed integrally with the support tube (50) of the outer filter element (20).

3. A gas filtration system (10; 10'; 10") according to any one of the preceding claims, wherein: The first end cap (24) of the outer filter element (20) has a first sealing section (42) for sealing abutment against the housing (12), preferably in an axial direction.

4. A gas filtration system (10; 10') according to any one of the preceding claims, wherein: The third end cap (34) has a third sealing section (44) for sealingly abutting against the housing (12), preferably in a radial direction.

5. The gas filtration system (10") according to any one of the preceding claims, wherein: The first end cap (24) of the outer filter element (20) and the third end cap (34) of the inner filter element (30) seal against each other.

6. The gas filtration system (10") according to claim 5, wherein: The first end cap (24) has a fourth sealing section (62) for sealingly abutting against the third end cap (34), preferably in a radial direction.

7. The gas filtration system according to claim 5, wherein: The third end cap (34) has a fourth sealing section for sealingly abutting against the first end cap (24), preferably in a radial direction.

8. The gas filter system (10; 10'; 10") according to any of the preceding claims, further comprising a housing (12), in which the outer filter element (20) and the inner filter element (30) can be arranged.

9. The gas filtration system (10; 10'; 10") according to claim 8, wherein: The housing (12) has a center tube (48) that extends into the inner filter element (30) at the third end cap (36).

10. The gas filtration system (10; 10'; 10") according to claim 9, wherein: The center tube (48) is retained at an axial collar (46) of the housing (12).

11. The gas filtration system (10; 10') according to claim 10, wherein: The third end cap (34) seals against the collar (46) or the center tube (48).

12. The gas filtration system (10; 10'; 10") according to any one of claims 9 to 11, wherein: The protrusion (52) and the center tube (48) overlap each other in the axial direction.

13. The gas filtration system (10; 10'; 10") according to any one of claims 8 to 12, wherein: The housing (12) has a dome (58) that projects into the projection (52) at the second end cap (26).

14. A gas filtering system (10; 10'; 10") according to any one of claims 9 to 12 and according to claim 13, wherein: The dome (58) and the center tube (48) overlap each other in the axial direction.

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

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

17. Use of an external filter element (20) and / or an internal filter element (30) in a gas filter system (10; 10'; 10") according to any of the preceding claims.

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