The invention relates to a filter material, provided in particular for hydraulic filters, having at least one filter layer, the individual filter folds of which are composed in each ease of a pair of filter fold halves, comprising a first structure, having warp threads and weft threads, and at least one further, second structure having a predefinable filtration characteristic.
Filter materials for manufacturing exchangeable filter elements in hydraulic systems are known in a variety of designs. These types of filter materials, in pleated or folded forms, having filter folds made of adjacent filter fold halves, are composed, for example, of one, or preferably numerous, layers made of a nonwoven filter medium, as a structure having a filtration characteristic, and of at least one structure in the form of a support layer on one or both sides thereof (inflow or outflow side). The structures forming the support layer, in the form of meshes having warp and weft threads, have the task of stabilizing the filter material. When the fluid flows through the filter material there are considerable pressure differences, in part, between the raw side and the clean side. In order to be able to maintain these pressure differences, as well as dynamic flow forces in the unfiltered product, known supporting structures are usually formed from metal meshes, in particular meshes made of stainless steel wires. Although such structures enable a good protection against loads due to pressure changes that arise during the operation of the filter element, the advantage of a greater mechanical stability, however, is offset by a decrease in fluid permeability of the filter material. if greater mesh sizes are provided in the meshes of such supporting structures, in order to obtain lower flow resistances, there is then the disadvantage, in turn, of a lower resistance against loads due to pressure changes during operation.
With regard to this problem, the invention addresses the object of providing a filter material, which ensures a high fluid permeability, despite good structural stability.
According to the invention, this object is achieved with a filter material having the features of Claim 1 in its entirety.
According to the characterizing portion of Claim 1, a substantial feature of the invention lies in that the structures are designed such and are operatively connected to one another such that at least one channel guide is formed, in particular by the configuration and geometry of the warp and weft threads of the first structure inside the filter layer, which channel guide enables an unimpeded flow through the respective filter fold half over, substantially, the entire fold height. Without needing to provide large mesh sizes for a respective supporting structure, and as a result having to forfeit the mechanical stability, it is thus possible to obtain particularly low flow resistances.
Particularly favorable flow conditions can be obtained when the warp threads run transverse to the longitudinal extension, and the weft threads run in the longitudinal extension, of the respective filter halves.
A respective supporting structure can be designed, with particular advantage, such that at least a first portion of the respective weft threads borders on open channel cross-sections, or extends over the entire fold height of a filter fold half in the form of a continuous channel section, having two thread sections that run substantially parallel to one another.
The configuration can be achieved thereby, to particular advantage, such that at least a portion of the respective weft thread assumes a curved course, and is supported, toward both the interior and exterior, preferably by warp threads disposed in pairs.
A mesh of this type, serving as a supporting structure, can be optimized for a particularly good permeability, such that at least a portion of the respective weft threads, over or under which, in each case, a pair of adjacent warp threads passes at a spacing thereto, border on these warp threads with right triangle flow-through cross-sections in each case, through which fluid can flow in the direction parallel to the warp threads, wherein the hypotenuse of the triangular cross-section is oriented parallel to the welt thread direction between the pair of warp threads, and one of the two legs is formed by the warp thread of a pair over which the associated well thread passes.
Further advantageous designs and further developments of the filter material are specified in the dependent Claims 6 to 12.
The subject matter of the invention also includes a filter element, having a filter material in a design according to one of the Claims 1 to 12.
The invention shall be explained in greater detail below, based on exemplary embodiments depicted in the drawings.
Therein:
The filter element, partially depicted in
With filter elements constructed in this manner, the filter mat 10 is normally composed of a support layer 18 serving as a supporting structure, a second layer 20 as a protective nonwoven, a third layer 22 as a main nonwoven or filter layer, and optionally, a further layer, not shown, of a likewise adjoining protective nonwoven, and in any case, a fourth layer as a further support layer 24, running on the internal circumference, as a further supporting structure. The support layers 18, 24 referred to above can be composed of a wire mesh, a plastic grid, or a plastic mesh. One of these support layers 18, 24 serves as a drainage layer in addition to its supporting function. The protective nonwovens 20 are normally composed of a plastic nonwoven, and the main nonwoven layer, or filter layer 22 is composed of materials such as glass fiber paper, synthetic filter material (melt-blown fibers), cellulose paper, or the like, The layers referred to above can also be made from so-called composite materials of the same type, or of a different type. Depending on the layer structure and the respective filter material employed therein, the filter mat 10 has predefinable filtering characteristics, which are oriented to the filtration task, wherein, fundamentally, a high differential pressure stability is desired, as well as a high beta-stability over a broad pressure difference range, and also predefinable filtering subtleties, wherein sufficient flow channels should be provided, in order to reduce the differential pressure at the filter element, while at the same time, however, a good resistance to changing pressure loads should be ensured.
Seen from the perspective of Fig. I, with the known filter element, fluid flows through the filter mat 10 from the exterior to the interior, and the filter element rests, at its relevant folds on its internal circumference, against the external circumference of the support tube 14, on the annular outlets thereof. The ends of the filter mat are each accommodated in an end cap, wherein only the upper end cap 26 is depicted in
The exemplary embodiment in
For optimal flow conditions, the mesh can be specially designed, as illustrated in
Number | Date | Country | Kind |
---|---|---|---|
10 2013 000 934.0 | Jan 2013 | DE | national |
Filing Document | Filing Date | Country | Kind |
---|---|---|---|
PCT/EP2014/000096 | 1/16/2014 | WO | 00 |