FILTER

Abstract

The invention relates to a filter with a gasket applied in line shape at an edge of the filter. The invention suggests to apply the gasket with a nozzle which facilitates a gasket that is thinner and/or whose protrusion beyond the filter is lower than this would be feasible for example through injection molding.

Claims

1.-11. (canceled)

12. A method for producing a filter including a gasket, the method comprising the step: applying the gasket to the filter through master forming without a molding tool, wherein the gasket is applied to the filter with a nozzle, and wherein the nozzle is temperature controlled.

13. A method for producing a filter including a gasket, the method comprising the step: applying the gasket to the filter through master forming without a molding tool, wherein the gasket is printed onto the filter.

14. The method according to claim 12, wherein the filter includes a frame which is applied to the filter through master forming without a molding tool.

15. The method according to claim 12, wherein the gasket or a frame is applied at an edge of the filter and envelope the edge of the filter.

16. The method according to claim 12, wherein the filter contacts a support when the gasket or a frame is applied, wherein the support includes an indentation in a portion of the gasket or of the frame. and wherein the gasket or the frame contacts the indentation.

17. The method according to claim 12, wherein the filter supports a membrane.

18. The method according to claim 12, wherein the gasket or a frame have a height above the filter of up to 500 μm.

19. The method according to claim 12, wherein the filter is subjected to a shape change in three dimensions.

20. The method according to claim 12, wherein the fitter includes at least one protrusion that is applied through master forming without a molding tool, and wherein the protrusion is taller than the gasket.

21. The method according to claim 12, wherein the gasket and a frame are is applied at an edge of the filter and envelop the edge of the filter.

22. The method according to claim 12, wherein the filter contacts a support when the gasket and a frame is applied, wherein the support includes an indentation in a portion of the gasket and of the frame, wherein the gasket and the frame contact the indentation.

23. The method according to claim 12, wherein the gasket or a frame have a height above the filter of up to 500 μm.

24. The method according to claim 12, wherein the gasket or a frame have a height above the filter of up to 200 μm.

25. The method according to claim 12, wherein the gasket or a frame have a height above the filter of up to 20 μm.

26. The method according to claim 12, wherein the gasket and a frame have a height above the filter of up to 500 μm.

27. The method according to claim 12, wherein the gasket and a frame have a height above the filter of up to 200 μm.

28. The method according to claim 12, wherein the gasket and a frame have a height above the filter of up to 20 μm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The invention is now described in more detail based on an embodiment with reference to drawing figures, wherein:

[0022] FIG. 1 illustrates a top view of a filter according to the invention;

[0023] FIGS. 2 a, b illustrate sectional views of the filter according to FIG. 1, in a portion of a gasket in a enlarged depiction;

[0024] FIG. 3 illustrates a second embodiment of the invention; and

[0025] FIG. 4 illustrates a third embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0026] The filter 1 according to the invention illustrated in FIG. 1 includes a fabric 2 made from plastic material fibers which is advantageously mechanically pulled off from a storage roll 3 and laid onto a CNC controlled table 4 that is moveable in X-direction and in Y-direction, this means longitudinally and transversally to the fabric 2, wherein the table forms a support surface for the filter 1 for applying a gasket 8. Instead of the fabric also a knitted material, a warp knitted material or a fleece can be used. Instead of being made from plastic material the fibers can also be made from glass, metal carbon material or stone or mixes thereof. An outer edge 5 and inner edges 6 of the filter 1 are illustrated in FIG. 1 with lines. The inner edges 6 enclose holes in the filter 1 for example for pass thru openings or threaded connections of a filter or machine housing that is not illustrated and which includes a separation plane in which the filter 1 is arranged.

[0027] With a nozzle 7 which is tilted sideways by 90° in FIG. 1 and which is arranged in a perpendicular plane at a slant angle or perpendicular to the filter 1 or to the table 4 a gasket material is applied to the filter 1 along the edges 5, 6. The gasket material is applied in a paste form and forms a permanently elastic line shaped gasket 8 along the edges 5, 6 of the filter 1 after curing. The gasket 8 can also be applied flat and/or inside the filter 1 and not only at the edges 5, 6 (not illustrated). As apparent from the sectional view of FIG. 2a the gasket 8 penetrates the woven material 2 of the filter 1 and encloses its fibers 9 so that a tight seal without pass thru openings is formed between the fibers 9. The gasket 8 is thin. In the instant embodiment it only protrudes by approximately 20 μm above a surface or top surface 10 of the filter 1. The surface or top surface 10 is an imaginary surface which contacts the fibers 9 of the fitters 1 at their extremities. In the embodiment the filter 1 has a thickness D of approximately 150 μm wherein the protrusion of the gasket 8 which is designated as h is not proportional to the thickness D of the filter 1 but as a matter of principle independent from the thickness D of the filter 1. The protrusion h of the gasket 8 over the top or cover surface 10 of the filter 1 can also be smaller, as a matter of principle it can be anywhere between 0, a couple of μm, a couple of 10 μm or a couple of 100 μm tall.

[0028] In the described embodiment of the invention the nozzle 7 is temperature controlled, for example water temperature controlled for applying for example silicone or for example electrically temperature controlled for applying for example thermo plastic material. In order to apply the gasket material to the filter 1 the gasket material is heated and plasticized in case it is not flow capable by itself and applied to the filter 1 with the nozzle 7 that is temperature controlled through water, electricity or in another manner. The gasket material is for example a plasticized duro plastic material or thermoplastic material, an elastomeric material or a thermally cross linked plastic material like for example silicone. However, the invention does not exclude a gasket material that can be applied to the filter 1 with a non temperature controlled nozzle 7 at room temperature.

[0029] As stated supra the table 4 includes a support for the filter 1 for applying the gasket 8 and it includes a channel along edges 5, 6 of the gasket 8 so that a protrusion of the gasket 8 also forms at a bottom side of the filter 1 over the surface or top surface of the gasket 8. The height h of the gasket 8 over the surface or top surface of the filter 1 can have identical sizes or different sized on both sides of the filter 1. Applying the gasket 8 with the with the nozzle 7 facilitates a gasket 8 which is thinner or whose protrusion h over the surface or top surface 10 of the filter 1 is smaller than it would be feasible through injection molding of a gasket in an injection molding tool.

[0030] After applying the gasket 8 the inner edges 6 are cut and the filter 1 is cut out along the outer edge 5. The edges 5, 6 of the filter 1 are cut within the gasket 8. The gasket 8 fixates the fibers 9 at the edges 5. 6 and prevents that short fiber pieces generated through the cutting operation separate from the filter 1 during use.

[0031] When the gasket 8 is applied at an edge of the filter 1, when the filter 1 is cut or stamped before applying the gasket 8, the gasket 8 encloses the edge of the filter 1 as apparent from FIG. 2b.

[0032] As evident in FIG. 2a on the left side the gasket material or another mass can also be built up higher than the gasket 8 to form protrusions 11. The protrusions 11 can be produced for example through multiple applications of gasket material or another compound in a straight or helical movement of the nozzle 7 oriented away from the filter 1. The protrusions 11 can be for example bases configured as spacers or for orienting the filter 1 or for automatically handling the filter 1 with a non illustrated robot.

[0033] After applying the gasket 8 through application with the nozzle 7 or imprinting, the filter 1 can be cambered through a deep drawing operation, this means through three dimensional shaping (not illustrated).

[0034] FIG. 3 illustrates a gasket 8 alternatively onto a filter 1 applied through printing for example with a printing roller 12. Instead of printing ink gasket material is applied to the filter 1 which as described with reference to FIGS. 1 and 2 penetrates the filter 1 and encloses the fibers of the filter 1 hermetically tight. In order to obtain greater thickness of the gasket 8 the gasket material can be printed onto the filter 1 several times, that means in layers. As a matter of principle all printing methods like letter press printing, flat printing, gravure printing, screen printing, flexo- or offset printing are feasible, wherein for printing methods which print individual dots (pixels) a method parameter like flow ability of the gasket material and its imprint on and into the fabric of the filter 1 shall be selected so that the individual printed dots flow into one another and a continuous line shaped or also flat gasket 8 without interruptions is formed. After printing the gasket 8 the gasket material can be pressed, for example calendared with one or plural rollers while it is not yet completely cured. This way individual dots printed from gasket material can be shaped or connected into a gasket 8 without interruptions and/or a thickness and/or protrusions h of the gasket 8 beyond the surface or top surface 10 of the filter 1 can be calibrated or adjusted to a particular dimension. Pressing or calendaring is also feasible for the gasket 8 of FIGS. 1 and 2 which are applied with the nozzle 7.

[0035] The gasket material is for example an elastomeric material, a hard plastic material like polyamide, polyester, for technical oils for example floor silicone or as a carrier for a membrane for a fuel cell for example polypropylene. After curing of the gasket material the gasket 8 is permanently elastic. The gasket 8 is made from a technical plastic material and does not include any intentional cavities, thus it is not a foam but a permanently elastic solid material without intentional pores or similar. This applies for the printed gasket 8 and also for the gasket 8 applied with the nozzle 7.

[0036] Instead of the gasket 8 or in addition to the gasket 8 a frame, for example made from a hard plastic material can be applied to the filter 1 in the same manner as the gasket 8. The gasket 8 can also simultaneously also a frame of the filter 1. The filter 1 can also include stiffeners or struts within its surface like a frame at an edge or edges of the filter 1.

[0037] FIG. 4 illustrates a fleece with fibers made from polypropylene as a carrier 13 for a membrane 14 of a non illustrated fuel cell. The fleece can also be interpreted as a filter; primarily however it is used as stated supra as a carrier for the membrane 14. The fleece forming the carrier 13 is applied to a suction table 15 that is CNC controlled and moveable in X-direction and in Y-direction, wherein the membrane 14 is applied to the fleece and a foil 16 for evacuating is applied to the membrane 14. The foil 16 overlaps the membrane 14 and the fleece 13 so that edges 17 of the foil 16 contact the suction table 15 laterally outside of the fleece and the membrane 14. The suction table 15 is penetrated by suction channels 18 and includes an evacuation chamber 19 at its bottom side through which air can be suctioned out through a vacuum pump so that the applied foil 16 sucks the membrane 14 onto the fleece forming the carrier 13. As described with respect to FIG. 1 a nozzle 7 is used to apply a plasticized gasket material along edges of the membrane 14 and of the fleece wherein the gasket material forms a line shaped permanently elastic gasket 8 after curing wherein the gasket 8 reaches around the membrane 14 and the fleece forming the carrier 13 and penetrates the fleece.

[0038] The membrane 14 is mechanically connected with the fleece through the gasket 8 and includes the gasket 8 at its edge. The foil 16 melts when the gasket material is applied so that it can be lifted off from the membrane 14 easily. Also here the gasket 8 can be applied by application with the nozzle 7 or as a matter of principle through printing in a thin layer and with a low protrusion that starts at zero and can be applied to a surface or top surface of the membrane 14 and the fleece forming the carrier 13.

[0039] Also in this embodiment the invention facilitates a gasket 8 which is thinner and/or includes a lower protrusion over the surface or top surface of the membrane 14 and carrier 13 than feasible through injection molding. When forming a carrier 13 for a membrane 14 of a fuel cell the gasket 8 is made form example from polypropylene.

[0040] In FIG. 4 a channel shaped indentation 21 is visible in the suction table 15 in the portion of the gasket 8, so that the gasket 8 also protrudes beyond the surface or top surface of the fleece forming the carrier 13 on a side that is oriented away from the nozzle 7.

[0041] The invention also facilitates to connect a multi layer filter with a gasket and/or a frame that is applied through master forming without a molding tool at the edges and/or within a surface of the filter.