Abstract
A filter element comprising a pleated filter mat (3), the terminal axial ends (7, 8) of which are connected by an end cap (9, 11) and which includes a main structural layer (15) having filtering properties and at least one first additional structural layer and a second additional structural layer (17, 19), the surface area of each of said additional structural layer (17, 19) being smaller than the surface area of the main structural layer (15), is characterized in that the axial ends (12, 14) of one additional structural layer (17) is located at n an axial distance from the axial ends (16, 18) of the other additional structural layer (19) on the filter mat (3).
Claims
1. A filter element comprising a pleated filter mat (3), the axial ends (7, 8) of which are each attached to an end cap (9, 11), which is provided with a main structural layer (15) with filtering properties as well as at least a first and a second additional structural layer (17, 19), which have a surface area each that is smaller than the surface area of the main structural layer (15), characterized in that the axial ends (12, 14) of the one additional structural layer (17) on the filter mat (3) are at an axial distance from the axial ends (16, 18) of the respective other additional structural layer (19).
2. The filter element according to claim 1, characterized in that two structural layers (17, 19) are provided and that at each of the two end caps (9, 11) an additional structural layer (17, 19) each is welded with one end (12, 18) together with the associated end (7, 8) of the main structural layer (15) into the respective end cap (9, 11).
3. The filter element according to claim 1, characterized in that the filter mat (3) is provided with a third stabilizing additional structural layer (23), the ends (25, 27) of which are disposed at an axial distance from the first (17) as well as the second structural layer (19) that are attached to an end cap (9, 11).
4. The filter element according to claim 1, characterized in that the additional structural layers (17, 19, 23) are provided without filtering properties.
5. The filter element according to claim 1, characterized in that the additional structural layers (17, 19, 23) are provided with filtering properties.
6. The filter element according to claim 1, characterized in that the additional structural layers (17, 19, 23) are pleated, having preferably the same type and amount of pleats (21) and are folded together with the main structural layer (15) into the filter mat (3).
7. The filter element according to claim 1, characterized in that the main structural layer (15) and/or the additional structural layers (17, 19, 23) are made of multiple layers.
8. The filter element according to claim 1, characterized in that the additional structural layers (17, 19, 23) are folded into the filter mat (3) either as outer or as inner layers.
9. The filter element according to claim 1, characterized in that the additional structural layers (17, 19, 23) are folded into the filter mat (3) either on the upstream side or on the downstream side.
10. The filter element according to claim 1, characterized in that the axial length of the additional structural layers (17, 19, 23) is variable.
11. A method for the manufacture of a filter element according to claim 1, characterized in that a preferably multiple-layered filter mat (3), consisting preferably of a multi-layered main structural layer (15) with filtering properties, is folded together with at least one further additional structural layer (17, 19, 23), that the filter mat (3) is formed into a circumferentially closed, hollow body along a longitudinal seam (5), and that the ends (7, 8) of the hollow body, which consist of main structural layer (15) and at least one additional structural layer (17, 19), are connected through welding or adhesive joining.
Description
[0012] The invention will now be explained in detail by way of exemplary embodiments shown in the drawing.
[0013] Shown are in:
[0014] FIG. 1 a perspective view of an exemplary embodiment of the filter element according to the invention;
[0015] FIG. 2 a perspective view of a section of the length of the filter mat of the exemplary embodiment of the filter element shown in a stretched-out state and shown enlarged compared to that of FIG. 1;
[0016] FIG. 3 a perspective view of an end section of the filter mat of the exemplary embodiment, formed into a hollow body, prior to insertion into an end cap;
[0017] FIG. 4 a depiction of the filter mat inserted into the end cap corresponding to that of FIG. 3; and
[0018] FIG. 5 a schematically simplified perspective view of a second exemplary embodiment of the filter element according to the invention.
[0019] FIG. 1 depicts a filter element according to a first exemplary embodiment of the invention, designated overall with 1. In a manner usual for circular-cylindrical filter elements, the filter medium is made from a pleated filter mat 3, which is formed into a hollow body that is closed circumferentially through a longitudinal seam 5, implemented through a welding seam or an adhesive connection. The filter mat 3, of which FIG. 2 shows a section of the length in a stretched-out state, is welded or glued into an end cap 9 and 11 at both axial ends 7 and 8 respectively, of which only one end is visible and designated with 7 in FIG. 3, wherein said end caps 9 and 11 form a rim for the end of the filter mat 3, as is common practice with filter elements of this kind. The end cap 9, which is shown at the top in FIG. 1 and is also shown in FIGS. 3 and 4, is made in form of a closed cap, whereas the lower end cap 11 is provided with a central passage 13 to the inner filter cavity, which is surrounded by the filter mat 3. When the flow travels through the filter mat 3 from outside to inside during filter operation, the inner hollow filter section may be provided with a fluid-permeable supporting tube (not shown in FIG. 1), which is in contact with the inside of filter mat 3. The end caps 9 and 11 are made from a plastic material that is suitable for a welding process, onto which components of the items to be joined will melt when end cap 9, 11 is heated up.
[0020] FIG. 2 dearly shows the design of the filter mat 3. From axial end 7 to axial end 8 it is provided with a continuous main structural layer 15, as well as a first additional structural layer 17 and a second additional structural layer 19, each of which is shorter than the main structural layer 15. During the folding process in the manufacture of filter mat 3, said additional structural layers 17 and 19 are folded in so that they start from an end 7 or 8 each. More precisely, the additional structural layer 17 starts with its end 12 at the end 7 of the filter material 3, and the additional structural layer 19 starts with its end 18 at the end 8 of the filter material 3, wherein the length of each structural layer 17, 19 is only a fraction of the axial length of the main structural layer 15. In practical application, as shown in FIG. 1, the axial length of each additional structural layer 17, 19 is approximately 1/15 of the length of the main structural layer 15. As is common for these kinds of filter materials, the main structural layer 15 is comprised of multiple layers, wherein a supporting fabric may be provided as a first layer, a protection fleece as a second layer, a main fleece as third layer, and wherein further layers may be provided as protection fleece and supporting fabric, wherein said supporting fabric may consist of a plastic mesh or a woven plastic if the mat structure is free of metal. The additional structural layers 17, 19 may consist of a fluid-impermeable plastic material, which forms a stabilizing filler between pleats 21 and consist of a material that is suitable for a welding process. Nevertheless, the additional structural layers 17, 19 may, just like components of the main structural layer 15, also consist of a plastic material with filtering properties, which supplies melt material for the welding process.
[0021] The additional structural layers 17, 19 may, during manufacture of the filter mat 3, be folded in together in such a way that the additional structural layers 17, 19 are in contact with the outside of the filter mat 3, as is apparent from FIG. 2, so that the each other facing ends 14 and 16 of the additional structural layers 17 and 19 are visible, as shown in FIG. 2. The additional structural layers 17, 19 may also be folded in on the inside between individual layers of the main structural layer 15, or on the inside or at the back (not visible in FIG. 2). The additional structural layers 17, 19 may advantageously consist of a material that hardens during the folding process or hardens subsequently after application of heat. For example a prepreg material may be used, preferably consisting of a base material of carbon fiber or glass fiber, wherein the associated quantity of resin is matched so that the material of the additional structural layers 17, 19 cures during the folding process or hardens in a further processing step through application of heat. Through the concentration of material at the endcaps 9, 11, caused by the additional structural layers 17, 19, a particularly secure embedding of the filter mat 3 into the end caps 9, 11 is ensured since for the welding process, which occurs through the heating up of the end caps 9, 11, more molten material is available which securely encloses the filter mat 3. Since the material concentration is only present in certain sections there is no significant increase in the overall material concentration of filter mat 3, hence there remains space between the pleats 21 to retain contaminant particles. Moreover, the filter mat 3 remains flexible. The greater flexibility in the sections without additional structural layers 17, 19 is advantageous for filter mat 3, for example in reverse pressure pulses during operation because the flexible filter mat 3 is able to expand and thus provide a greater amount of free, flow-exposed surface area.
[0022] FIG. 5 depicts a further exemplary embodiment of the filter element 1 according to the invention. This concerns an embodiment of comparatively long construction. In addition to the additional structural layers 17, 19, which extend from the end caps 9 and 11, a third additional structural layer 23 is provided in this example. In the example shown, said layer is folded centrally into the web of filter mat 3, at a distance to the additional structural layers 17, 19, so that it is placed on the outside of the main structural layer 15, like the additional structural layers 17, 19, and that the ends 25 and 27 of the additional structural layer 23 are located at a distance from the adjacent ends 14 and 16 of the additional structural layer 17 and 19 respectively. Said third additional structural layer 23 consists of filler material which, like the material of the other additional structural layers 17, 19, cures or may cure during the folding process, and serves as stabilizing spacer that keeps the space between the pleats 21 open over the length of the element. Just like the two other additional structural layers 17 and 19, the third additional structural layer 23 may also be provided with filtering properties or be made of fluid-impermeable filler.
