Gas Filter System

Abstract

The present invention provides a gas filter system (10) comprising an outer filter element (20) having a first filter medium (22) disposed between a first end cap (24) and a second end cap (26), and an inner filter element (30) having a second filter medium (32) disposed between a third end cap (34) and a fourth end cap (36), wherein the first filter medium (22) is positionable to surround the second filter medium (32), and the first, third, and fourth end caps (24, 34, 36) are interdigitated. 6) is open, the outer filter element (20) is closed by a second end cap (26), the outer filter element (20) has an axial protrusion (52) on the second end cap (26), the protrusion (52) protruding into the inner filter element (30) and having a radially outwardly facing sealing surface (54), and a fourth end cap (36) of the inner filter element (30) has a second sealing portion (56) for sealingly abutting against the sealing surface (54) of the protrusion (52).

Description

[Technical Field]

[0001] The present invention relates to a gas filter system comprising an outer filter element having a first filter medium disposed between a first end cap and a second end cap, and an inner filter element having a second filter medium disposed between a third end cap and a fourth end cap, wherein the first filter medium can be positioned to surround the second filter medium. [Background technology]

[0002] Such a filter system is known from DE 10 2018 215 603 A1.

[0003] In some applications, a gas stream must be filtered through two filter elements. Typically, the gas flows through the first filter element, followed by the pre-filtered gas flowing through the second filter element. The filter elements can be located within a common housing. This type of filter system is used, for example, to filter combustion air for large combustion engines such as trucks and construction vehicles. Another application is filtering air for fuel cells.

[0004] German Patent Application Publication No. 102018215603 discloses a gas filter system having a first filter element surrounding a second filter element. At first axial ends, the open end caps of the two filter elements are associated with a clean air outlet. At second axial ends, the first (outer) filter element has an open end cap, and the second (inner) filter element has a closed end cap. The closed end cap of the inner filter element is arranged to close the opening of the end cap of the outer filter element at the second axial end.

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

[0006] 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 set out in the dependent claims and the description. Summary of the Invention

[0007] According to the present invention, a gas filter system is provided, comprising an outer filter element having a first filter medium disposed between first and second end caps, and an inner filter element having a second filter medium disposed between third and fourth end caps.

[0008] The first filter medium can be arranged to surround the second filter medium. The filter medium can be hollow cylindrical or conical, preferably having a generally circular or elliptical cross section. The filter mediums each surround a longitudinal axis. In particular, the filter mediums are arranged concentrically about a common longitudinal axis. Directions such as radial and axial refer to the longitudinal axis. In principle, the first and third end caps are associated with the first axial end, and the second and fourth end caps are associated with the second axial end.

[0009] During use of the gas filter system, the gas flow typically first passes through the first filter medium of the outer filter element and then through the second filter medium of the inner filter element.

[0010] In accordance with the present invention, the first, third, and fourth end caps are open. The first, third, and fourth end caps typically have a central opening.

[0011] The outer filter element is closed with a second end cap, which may be a monolithic closure end cap, or a closure means may be permanently attached to the outer filter element for sealing the second end cap.

[0012] According to the present invention, the outer filter element has an axial protrusion at the second end cap that protrudes into the inner filter element when the filter element is placed for filtering in the gas filter system. The protrusion provides a guide between the filter elements, particularly during installation. The protrusion typically protrudes axially beyond the fourth end cap of the inner filter element.

[0013] Furthermore, according to the present invention, the protrusion has a sealing surface facing radially outward, in other words, a sealing surface facing radially outward is formed on the protrusion.

[0014] The fourth end cap of the inner filter element has a (second) sealing portion for sealingly abutting against the sealing surface of the protrusion, thereby sealing the two filter elements to each other at the second end. Because the second end cap of the outer filter element is closed over the inner filter element, the filter elements, particularly the inner filter element, are also sealed against the environment, such as the inlet side of the filter system.

[0015] The second seal may be integral with the fourth end cap. Typically, the second seal is made of a softer material than the material of the protrusion. In particular, the seal or the entire fourth end cap is made of polyurethane, preferably foamed polyurethane. The protrusion may be made of a hard plastic.

[0016] Generally, the seals described in the context of the present invention are softer than the mating parts they seal. In particular, each seal is made of polyurethane, preferably foamed polyurethane. The respective mating parts may be made of hard plastic.

[0017] Preferably, the protrusion is integrally formed with the support tube of the outer filter element. In other words, the support tube closes the second end cap and forms the protrusion. The support tube reinforces the outer filter element. The support tube can be partially embedded in the second end cap.

[0018] The second end cap may have at least one support leg for axially supporting the outer filter element relative to the housing, and the support leg may be integrally formed with the second end cap.

[0019] The first end cap of the outer filter element may have a first seal for sealingly abutting, preferably axially, against the housing. Alternatively or additionally, the first seal may provide a radial sealing abutment against the housing.

[0020] The third end cap of the inner filter element may have a third seal for sealingly abutting against the housing, preferably in a radial direction. Alternatively or additionally, the third seal may provide an axial sealing abutment against the housing.

[0021] Preferably, the first end cap of the outer filter element and the third end cap of the inner filter element are sealed to each other, preventing gas flow from the environment, such as the inlet side, into the space between the filter elements or from the space between the filter elements into the environment, thereby ensuring continuous gas flow through the two filter elements.

[0022] The first end cap may have a fourth seal for sealingly abutting, preferably radially, against the third end cap.

[0023] Alternatively, the third end cap may have a fourth seal for sealingly abutting, preferably radially, against the first end cap.

[0024] Preferably, the gas filter system further includes a housing in which the inner and outer filter elements can be disposed. In the installed state, the filter elements are disposed within the housing. Typically, the housing includes a first housing portion associated with the first end and a second housing portion associated with the second end. The inlet may be formed in either the first or second housing portion. The outlet is preferably formed in the first housing portion. The outlet may be in fluid communication with the clean side of the inner filter element.

[0025] The housing may have a central tube that extends into the inner filter element at the third end cap when the filter system is installed, the central tube providing a guide for the inner filter element and supporting the second filter medium.

[0026] The central tube can be held in an axial collar of the housing, which is advantageous in manufacturing the filter housing, and a snap fit may be provided between the collar and the central tube.

[0027] The third end cap may be sealed to the collar or center tube, and in particular, a third seal of the third end cap sealingly abuts the collar or center tube, thereby advantageously sealing the interior of the inner filter element to the housing.

[0028] The protrusion and the central tube may be arranged to overlap each other in the axial direction, thereby providing mutual guidance and support between the central tube and the outer filter element, which also facilitates installation of the filter system. In particular, the protrusion may be engaged with the central tube. In other words, the central tube may surround the protrusion radially outward.

[0029] Preferably, the housing has a dome projecting into the protrusion at the second end cap, which can provide additional support for the outer filter element, particularly the mounting guide, during use of the filter system.

[0030] Furthermore, the dome and the central tube may be arranged to overlap each other in the axial direction. This design effectively prevents undesired movement of the filter element during operation. In the event of large vibrations, the central tube can contact the dome via a protrusion disposed between the central tube and the dome.

[0031] The first or second filter medium, especially the second filter medium of the inner filter element, may have gas adsorption properties and preferably comprises activated carbon. Typical harmful gases include SO2, NO X , NH3.

[0032] The first or second filter medium, particularly the first filter medium of the outer filter element, may be composed of cellulose.

[0033] The first and / or second filter media may be pleated.

[0034] The present invention also relates to the use of the outer filter element and / or the inner filter element in a gas filter system according to the invention, as described above, which can be used for cathode air filtration in fuel cells of electric vehicles.

[0035] Other advantages and features of the present invention will be apparent from the following description of embodiments of the invention, with reference to the drawings showing important details, and from the claims. The individual features as described above or below may be implemented individually or in any useful combination in variants of the invention. [Brief explanation of the drawings]

[0036] [Figure 1] 1 is a schematic cross-sectional view of a first embodiment of a gas filter system according to the present invention, comprising an outer filter element, an inner filter element, and a housing. [Figure 2] 2 is a schematic cross-sectional view of an outer filter element of the gas filter system of FIG. 1. [Figure 3] 2 is a schematic cross-sectional view of an inner filter element of the gas filter system of FIG. 1. [Figure 4] FIG. 2 is an enlarged view of a first end of the filter system of FIG. 1. [Figure 5] FIG. 2 is an enlarged view of a second end of the filter system of FIG. 1. [Figure 6] 4 is a schematic cross-sectional view of a first end of a second embodiment of a filter system according to the present invention. FIG. [Figure 7] FIG. 10 is a schematic cross-sectional view of a first end of a third embodiment of a filter system according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0037] 1 illustrates a gas filter system 10. The filter system 10 includes a housing 12. The housing has a first housing portion 14 and a second housing portion 16 that are attachable to one another. An inlet 18 allows gas to enter the housing 12. Here, the inlet 18 is formed in the first housing portion 14. A filtered gas outlet 19 is also formed in the first housing portion 14. The housing portions 14, 16 may be made of metal and / or rigid plastic.

[0038] The filter system 10 further includes an outer filter element 20 (see also FIG. 2). The outer filter element 20 has a first filter medium 22. The first filter medium 22 is housed between a first end cap 24 and a second end cap 26. The first filter medium 22 circumferentially surrounds a longitudinal axis 28. The first filter medium 22 may be constructed from pleated cellulose paper.

[0039] The filter system 10 further includes an inner filter element 30 (see also FIG. 3). The inner filter element 30 has a second filter medium 32. The second filter medium 32 is housed between a third end cap 34 and a fourth end cap 36. The second filter medium 32 also circumferentially surrounds the longitudinal axis 28. The second filter medium 32 may include activated carbon for gas adsorption properties.

[0040] The inner filter element 30 is disposed inside the outer filter element 20. Both filter elements 20, 30 are disposed within the housing 12, where the first and second filter media 22, 32 are concentric with each other and with respect to the longitudinal axis 28.

[0041] At the first end of the filter system 10, a first end cap 24 is positioned to surround a third end cap 34 (see also FIG. 4). The first end cap 24 and the third end cap 34 each have a central opening (see FIGS. 2 and 3, respectively). The outlet 19 is in fluid communication with the clean side 40 within the inner filter element 30 (see FIG. 1).

[0042] The first seal portion 42 protrudes axially from the first end cap 24. The first seal portion 42 is in axial sealing contact with the first housing portion 14. Here, the first end cap 24 having the first seal portion 42 is integrally formed from foamed polyurethane.

[0043] The third seal 44 projects axially from the third end cap 34. The third seal 44 sealingly abuts radially against the first housing part 14. In particular, the third seal sealingly abuts against a collar 46 that projects axially into the housing 12 at the outlet 19. Here, the third end cap 34 and the third seal 44 are integrally formed from foamed polyurethane.

[0044] A central tube 48 of the housing 12 is retained in the axial collar 46. The central tube 48 extends through an opening in the third end cap 34 toward the fourth end cap 36. The central tube 48 may be constructed of a hard plastic.

[0045] The outer filter element includes a support tube 50. The support tube extends from the first end cap 24 to the second end cap 26, inside the first filter media 22. The support tube 50 may be partially embedded in the first and / or second end caps 24, 26. The support tube 50 may be constructed of a hard plastic.

[0046] At the second end, a support tube 50 sealingly closes the outer filter element 20. In the second end cap 26, the support tube 50 forms a closed projection 52 (see also FIG. 5 ). The projection 52 extends through a central opening in the fourth end cap 36 of the inner filter element 30 to the clean side of the inner filter element 30.

[0047] The fourth end cap 36 is sealed against the protrusion 52. The protrusion 52 is formed with a sealing surface 54 facing radially outward. A second sealing portion 56 is formed at the opening of the fourth end cap 36. Here, the fourth end cap 36 and the second sealing portion 56 are integrally formed from foamed polyurethane. The second sealing portion 56 is in sealing contact with the sealing surface 54 of the protrusion 52 in the radial direction.

[0048] The central tube 48 of the housing 12 and the protrusion 52 of the outer filter element 20 overlap one another along the longitudinal axis 28. The protrusion 52 may be tapered above the sealing surface 54 so that it extends into the central tube 48.

[0049] The housing may have a dome 58. Here, the dome 58 is formed in the second housing portion 16. The dome 58 extends toward the inside of the inner filter element 30. In particular, the dome 58 extends into the protrusion 52 of the outer filter element 20. More particularly, the dome 58 and the central tube 48 overlap one another along the longitudinal axis 28.

[0050] The second embodiment of the gas filter system 10', partially shown in Figure 6, substantially corresponds to the first embodiment of the gas filter system 10 (see Figures 1-5 and the above description). The filter system 10' differs from the gas filter system 10 in that in the second embodiment, the third end cap 34 is sealed to the central tube 48. The third seal 44 sealingly abuts the central tube 48 radially, here slightly below the collar 46.

[0051] The third embodiment of the gas filter system 10'', partially shown in FIG. 7, is also substantially identical to the first embodiment of the gas filter system 10 (see FIGS. 1-3).

[0052] In the third embodiment, the first end cap 24 of the outer filter element 20 is axially and radially sealed to the housing 12. The first housing portion 14 has a circumferential rib 60 against which the first seal portion 42 of the first end cap 24 radially abuts.

[0053] 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 to one another. The first end cap 24 further includes a fourth seal 62. The first end cap 24, including the first seal 42 and the fourth seal 62, is integrally formed from foamed polyurethane. The third end cap 34 is constructed from a hard plastic and is bonded to the second filter medium 32. The fourth seal 62 sealingly abuts the third end cap 34 in the radial direction. [Explanation of symbols]

[0054] Gas filter system 10;10';10” Housing 12 First housing part 14 Second housing part 16 Inlet 18 Outlet 19 Outer filter element 20 First filter element 22 First End Cap 24 Second End Cap 26 Longitudinal axis 28 Inner filter element 30 Second filter element 32 Third End Cap 34 4th end cap 36 Clean side 40 First seal portion 42 Third seal 44 Color 46 central tube 48 Support tube 50 Projection 52 Sealing surface 54 Second seal part 56 Dome 58 Rib 60 Fourth seal part 62

Claims

1. A gas filter system (10; 10'; 10") comprising: an outer filter element (20) having a first filter medium (22) disposed between a first end cap (24) and a second end cap (26); an inner filter element (30) having a second filter medium (32) disposed between a third end cap (34) and a fourth end cap (36); The first filter medium (22) can be arranged to surround the second filter medium (32); the first, third, and fourth end caps (24, 34, 36) are open; The outer filter element (20) is closed with the second end cap (26), the outer filter element (20) has an axial protrusion (52) on the second end cap (26), the protrusion (52) protruding into the inner filter element (30) and having a radially outwardly facing sealing surface (54); The fourth end cap (36) of the inner filter element (30) has a second sealing portion (56) for sealingly abutting against the sealing surface (54) of the protrusion (52).

2. 2. The gas filter system (10; 10'; 10") of claim 1, wherein said protrusion (52) is integrally formed with a support tube (50) of said outer filter element (20).

3. 3. A gas filter system (10; 10'; 10") according to claim 1 or 2, wherein the first end cap (24) of the outer filter element (20) has a first seal (42) for sealingly abutting against the housing (12), preferably in the axial direction.

4. A gas filter system (10; 10') according to any one of claims 1 to 3, wherein the third end cap (34) has a third seal portion (44) for sealingly abutting against the housing (12), preferably in the radial direction.

5. The gas filter system (10") of any one of claims 1 to 4, wherein 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 to one another.

6. 6. The gas filter system (10") of claim 5, wherein the first end cap (24) has a fourth seal (62) for sealingly abutting, preferably radially, against the third end cap (34).

7. 6. A gas filter system according to claim 5, wherein said third end cap (34) has a fourth seal for sealingly abutting, preferably radially, against said first end cap (24).

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

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

10. 10. The gas filter system (10; 10'; 10") of claim 9, wherein the central tube (48) is retained in an axial collar (46) of the housing (12).

11. 11. The gas filter system (10; 10') of claim 10, wherein the third end cap (34) is sealed to the collar (46) or the center pipe (48).

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

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

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

15. 15. The gas filter system (10; 10'; 10") according to any one of claims 1 to 14, wherein the first or second filter medium (22, 32), in particular the second filter medium (32) of the inner filter element (30), has gas adsorption properties and preferably comprises activated carbon.

16. 16. A gas filter system (10; 10'; 10") according to any one of claims 1 to 15, wherein the first or second filter medium (22, 32), in particular the first filter medium (22) of the outer filter element (20), is made of cellulose.

17. Use of an outer filter element (20) and / or an inner filter element (30) in a gas filter system (10; 10'; 10") according to any one of claims 1 to 16.

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