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 end cap (24), the second end cap (26) and the third end cap (34) are open; the inner filter element (30) is closed at a fourth end cap (36); the first filter medium (22) may be arranged around the second filter medium (32) such that the first end cap (24) of the outer filter element (20) surrounds the third end cap (34) of the inner filter element (30), the first end cap (24) and the third end cap (34) being sealed against each other, and such that the second end cap (26) of the outer filter element (20) surrounds the fourth end cap (34) of the inner filter element (30), the third end cap (34) being sealed against each other. The second end cap (26) and the fourth end cap (36) are sealed against each other.

Description

Technical Field

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

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

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

[0004] The first end cap, the second end cap and the third end cap are open,

[0005] The inner filter element is closed at the fourth end cap,

[0006] The first filter medium may be arranged to surround the second filter medium. Background Art

[0007] Such a filter system is known from DE 10 2018 215 603 A1.

[0008] 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 may 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.

[0009] DE 10 2018 215 603 A1 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.

[0010] 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 combined use.

[0011] This is achieved by the use of a gas filter system according to claim 1 and a filter element according to claim 15. Advantageous embodiments are given in the dependent claims and in the description. Summary of the invention

[0012] According to the present invention, a gas filtration system is provided. The gas filtration system comprises

[0013] - an outer filter element having a first filter medium disposed between a first end cap and a second end cap; and

[0014] - an inner filter element having a second filter medium disposed between the third end cap and the fourth end cap.

[0015] The first end cap, the second end cap and the third end cap are open. The first end cap, the second end cap and the third end cap generally have a central opening.

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

[0017] The first filter medium may be arranged to surround the second filter medium. The filter medium may be hollow cylindrical or conical, preferably having 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 indications refer to the longitudinal axis of the filter system. 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. The end caps cover the filter medium in the axial direction and will generally have the same geometry as the filter medium in a cross-sectional view, such as a circle or annulus.

[0018] 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.

[0019] According to the present invention, when the outer filter element is arranged around the inner filter element for use in a gas filtration system, the first end cap of the outer filter element surrounds the third end cap of the second filter element, and the second end cap of the outer filter element surrounds the fourth end cap of the inner filter element. In other words, the first end cap and the third end cap are arranged at the same axial height along the longitudinal axis. Similarly, the second end cap and the fourth 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 preferably sealed against each other in a radial direction, and the second end cap and the fourth end cap are preferably sealed against each other in a radial direction. The intermediate space between the first filter medium and the second filter medium is sealed at the first end by the first end cap and the third end cap being sealed against each other. The intermediate space between the first filter medium and the second filter medium is sealed at the second end by the second end cap and the fourth end cap being sealed against each other. Therefore, the gas to be filtered must flow through the two filter media continuously. The end caps being arranged at the same axial height does not necessarily mean that the filter bellows have the same height. For example, in the case of a shorter inner filter element, the third end cap may include an axial extension or collar for abutting against the first end cap of the outer filter element.

[0020] The first end cap of the outer filter element may have a first sealing section for sealing abutment against the housing, preferably in radial direction. Alternatively or additionally, the first sealing section may provide axial sealing abutment against the housing. The first sealing section may be an integral part of the first end cap.

[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] The first end cap of the outer filter element may have a second sealing section for sealingly abutting against the third end cap of the inner filter element, preferably in radial direction. The second sealing section may be an integral part of the first end cap. Preferably, the first end cap with the first sealing section and / or the second sealing section is an integral foam component. If the first end cap has a (soft) second sealing section, the third end cap is typically made of a harder material such as a rigid plastic and may be glued to the second filter medium.

[0023] Alternatively, the third end cap of the inner filter element may have a second sealing section for sealingly abutting against the first end cap of the outer filter element, preferably in radial direction. The second sealing section may be an integral part of the third end cap. In this case, the second end cap may preferably be an integral foam component. The first end cap is then typically made of a harder material such as a rigid plastic and may be glued to the first filter medium.

[0024] The second end cap of the outer filter element may have a third sealing section for sealingly abutting against the fourth end cap of the inner filter element, preferably in radial direction. Preferably, the third end cap with the third sealing section is an integral foam component. If the second end cap has a (soft) third sealing section, the fourth end cap is typically made of a harder material such as a rigid plastic and can be glued to the second filter medium.

[0025] Alternatively, the fourth end cap of the inner filter element may have a third sealing section for sealingly abutting against the second end cap of the outer filter element, preferably in radial direction. The third sealing section may be an integral part of the fourth end cap. In this case, the fourth end cap may preferably be an integral foam component. The second end cap is then typically made of a harder material such as a rigid plastic and may be glued to the first filter medium.

[0026] The end cap with at least one sealing section can be made of polyurethane, in particular polyurethane foam. The end cap against which the sealing section abuts can be made of rigid plastic. The plastic end cap can be glued to the corresponding filter medium.

[0027] 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.

[0028] 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.

[0029] The inner filter element has an axial projection at the fourth end cap, which projects into the inner hollow space of the inner filter element. Preferably, the projection is integrally formed with the fourth end cap. Alternatively, the projection may constitute the closing means of the fourth end cap.

[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 central 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 central tube.

[0032] Preferably, 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 internal 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 outwards.

[0033] Preferably, the housing has a dome which projects into the boss at the fourth end cap.The dome may provide guidance during installation and, in particular, additional support for the internal filter element during use of the filter system.

[0034] 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.

[0035] If the first filter element and / or the second filter element have a rotationally symmetrical shape, it may be advantageous to add the feature of being installed in a defined position. The projection, the central tube, and preferably also the dome can have a corresponding projection or recess in the radial direction. In this way, the internal filter element and preferably also the cover can be installed in a defined rotational position. Similarly, the second end cap and the fourth end cap can have a projection or recess, so as to limit the relative position of the internal filter element and the external filter element in the circumferential direction. Additionally or alternatively, the inner wall of the second end cap and the housing can have a corresponding projection and recess.

[0036] The first filter medium or the second filter medium, in particular the second filter medium of the inner filter element, may have gas adsorption properties and preferably contain activated carbon. Typical harmful gases are SO 2 、NO x and NH 3。

[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 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 The second end of the filtration system. DETAILED DESCRIPTION

[0046] 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 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.

[0047] 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.

[0048] The filter system 10 also includes an internal filter element 30, see also Figure 3 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 a circular manner. The second filter media 32 may be pleated and may contain activated carbon to achieve gas adsorption properties.

[0049] 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.

[0050] 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 .

[0051] The first end cap 24 of the outer filter element 20 seals axially and / or radially against the housing 12. A first sealing section 42 protrudes axially from the first end cap 24. The first sealing section 42 abuts the first housing portion 14 in the axial direction and in the radial direction. The first housing portion 14 has a circumferential rib 44 against which the first sealing section 42 of the first end cap 24 rests in the radial direction.

[0052] The first end cap 24 and the third end cap 34 seal against each other. In the illustrated embodiment, a radial seal is established. The first end cap 24 has a second sealing section 46. The second sealing section 46 sealingly abuts the third end cap 34 in the radial direction.

[0053] In the illustrated embodiment, the first end cap 24 is integrally made of polyurethane foam with the first and second sealing sections 42, 46. In other words, the first end cap 24 and its sealing sections 42, 46 are a unitary component. The third end cap 34 is made of rigid plastic and is glued to the second filter medium 32.

[0054] The center tube 48 of the housing 12 is held in place by an axial collar 50, see Figure 1 and Figure 4 The collar 50 projects axially into the housing 12 at the outlet 19. The center tube 48 extends through the opening of the third end cap 34 toward the fourth end cap 36. The center tube 48 may be made of a rigid plastic.

[0055] At the second end of the filter system 10, the second end cap 26 is arranged to surround the fourth end cap 36, see also Figure 5 The second end cap 26 has a central opening, see also Figure 2 The fourth end cap 36 is closed, see also Figure 3 In the illustrated embodiment, the fourth end cap 36 is an integral closed end cap. The fourth end cap 36 may be made of a rigid plastic and is preferably glued to the second filter media 32.

[0056] The second end cap 26 and the fourth end cap 36 are sealed against each other. In the illustrated embodiment, a radial seal is established. The second end cap 26 has a third sealing section 52. The third sealing section 52 is sealingly adjacent to the fourth end cap 36 in the radial direction. The second end cap 26 and the third sealing section 52 can be made integrally of polyurethane foam. In other words, the second end cap 26 and its sealing section 52 are an integral part.

[0057] The fourth end cap 36 forms a protrusion 54 in a central region thereof (radially within the second filter medium 32), see Figure 1 , Figure 3 and Figure 5 The projection 54 extends into the inner filter element 30 in an axial direction towards the third end cap 34 .

[0058] The center tube 48 of the housing 12 and the projection 54 of the inner filter element 30 overlap one another along the longitudinal axis 28. The projection 54 may be tapered so as to extend into the center tube 48.

[0059] The housing 12 may have a dome 56. Here, the dome 56 is formed at the second housing portion 16, which may be a removable cover. The dome 56 extends toward the interior of the inner filter element 30. In particular, the dome 56 extends into the protrusion 54 of the inner filter element 30. More specifically, when the protrusion 54 protrudes into the center tube 48, the dome 56, the protrusion 54, and the center tube 48 overlap each other along the longitudinal axis 28.

[0060] Reference numerals

[0061] Gas filtration system 10

[0062] Housing 12

[0063] First housing part 14

[0064] Second housing part 16

[0065] Entrance 18

[0066] Exit 19

[0067] External filter element 20

[0068] First filter medium 22

[0069] First end cap 24

[0070] Second end cap 26

[0071] Longitudinal axis 28

[0072] Internal filter element 30

[0073] Second filter medium 32

[0074] The third end cap 34

[0075] Fourth end cap 36

[0076] Clean side 40

[0077] First sealing section 42

[0078] Rib 44

[0079] Second sealing section 46

[0080] Center tube 48

[0081] Ring 50

[0082] The third sealing section 52

[0083] Protrusion 54

[0084] Dome 56

Claims

1. 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 a third end cap (34) and a fourth end cap (36); The first end cap (24), the second end cap (26) and the third end cap (34) are open; The inner filter element (30) is closed at the fourth end cap (36); 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), the first end cap (24) and the third end cap (34) are sealed against each other, and the second end cap (26) of the outer filter element (20) surrounds the fourth end cap (34) of the inner filter element (30), the second end cap (26) and the fourth end cap (36) are sealed against each other, wherein The inner filter element (30) has an axial protrusion (54) at the fourth end cap (36), and the protrusion (54) protrudes into the inner hollow space of the inner filter element (30).

2. The gas filtration system (10) according to claim 1, wherein: The fourth end cap (34) is an integral closed end cap.

3. 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) has a first sealing section (42) for sealing abutment against the housing (12), preferably in a radial direction.

4. 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) has a second sealing section (46) for sealingly abutting against the third end cap (34) of the inner filter element (30), preferably in a radial direction.

5. The gas filtration system (10) according to claim 3 and claim 4, wherein: The first end cap (24) is a unitary foam component.

6. The gas filtration system (10) according to any one of the preceding claims, wherein: The second end cap (26) of the outer filter element (20) has a third sealing section (52) for sealingly abutting against the fourth end cap (34) of the inner filter element (30), preferably in a radial direction.

7. The gas filter system (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) are arrangeable.

8. The gas filtration system (10) according to claim 7, wherein: The housing (12) has a center tube (48) that extends into the inner filter element (30) at the third end cap (34).

9. The gas filtration system (10) according to claim 8, wherein: The protrusion (54) and the center tube (48) overlap each other in the axial direction.

10. The gas filtration system (10) according to any one of claims 7 to 9, wherein: The housing (12) has a dome (56) that protrudes into the projection (54) at the fourth end cap (36).

11. The gas filtration system (10) according to claim 8 or 9 and claim 10, wherein: The dome (56) and the center tube (48) overlap each other in the axial direction.

12. The gas filtration system (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.

13. The gas filtration system (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.

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

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