FLAT MATERIAL, FILTER ELEMENT, FILTER AND METHOD FOR PRODUCING A FLAT MATERIAL

Description

[0001] The invention relates to a corrugated or folded flat material of a filter element with the features of the preamble of claim 1. Such a flat material is known, for example, from WO 2009 / 026978 A2. The invention further relates to a filter element, a filter, and a method for producing the flat material. Document CN 204 509 608 U discloses a fabric layer with at least two fabric strips.

[0002] Using such flat materials, foreign substances, such as contaminating particles, can be removed from a liquid, thus reducing the concentration of foreign substances in the liquid as it flows through the material. To increase the effective surface area of ​​the material, it is folded or corrugated. This increases the effectively usable area without increasing the material's external dimensions. Such a flat material is also called a filter bellows. The pressure exerted on the material by the flowing fluid can cause the folds or corrugations on the downstream side of the material to become tightly packed. This increases the flow resistance of the material and thus the pressure drop of the fluid as it flows through it. Therefore, in the known flat material, the fabric layer is designed to be deformable and have a twill weave.This increases the mechanical strength of a corrugated or folded flat material manufactured with such a fabric layer and reduces the risk of damage under alternating pressure loads. Despite its high mechanical strength, the known flat material is characterized by low flow resistance due to its twill weave.

[0003] When processing the known fabric layer into a flat material, rework may be necessary because the threads of the fabric layer can detach locally from the fabric layer at certain points during processing.

[0004] The invention is based on the objective of improving a corrugated or folded flat material of a filter element in such a way as to simplify the processing of the fabric layer. The invention is further based on the objective of providing a filter element, a filter, and a method for producing a flat material.

[0005] According to the invention, this problem is solved with regard to the flat material by the subject matter of claim 1. The problem is solved with regard to the filter element by the subject matter of claim 9, with regard to the filter by the subject matter of claim 12, and with regard to the method by the subject matter of claim 13.

[0006] Specifically, the problem is solved by a flat material according to claim 1.

[0007] The advantages of the invention are described below with reference to the fabric strips.

[0008] The invention has the advantage that locally different functions or properties of the tissue layer can be set by selecting the appropriate binding method. This is achieved by changing the binding method of the tissue layer at the transition from the first to the second tissue strip. The change in binding methods enables a different function or property in the area of ​​the first binding method of the tissue layer than in the area of ​​the second binding method of the tissue layer, since the first and second binding methods differ from each other.

[0009] For example, in areas critical to the processing of the fabric layer, a second binding method different from the first can be used, which allows for better fixation of the threads in the fabric layer than in the area of ​​the first binding method. This simplifies the processing of the fabric layer, as post-processing of the flat material is no longer necessary, at least with regard to the fabric layer.

[0010] The invention is not limited to simplifying processing. Rather, it generally allows for the local adjustment of certain functions or properties of the fabric layer, thereby improving, for example, the performance of the filter element. This is achieved through the different bonding methods of the fabric layer.

[0011] The invention is not limited to two different types of bonding. It is possible to use more than two, for example three or four types of bonding, each of which differs from the first type of bonding.

[0012] Preferred embodiments of the invention are specified in the dependent claims.

[0013] In a particularly preferred embodiment, the second fabric strip forms a fixing bond that secures the threads, especially the warp threads, of the first fabric strip. This embodiment is particularly suitable for simplifying the processing of the fabric layer because the second bond prevents the threads from coming loose from the fabric layer. This embodiment is especially suitable for securing the edge threads of the fabric layer.

[0014] Preferably, the second weave of the second fabric strip comprises a plain weave (also called a plain weave) or a twill weave. It has been shown that plain weave or twill weave provides better fixation of the threads, especially the warp threads, within the fabric layer than, for example, a twill weave. By combining the different weave types, the optimal properties of each are retained and specifically used to improve the properties of the fabric layer.

[0015] In a further preferred embodiment, the second fabric strip forms the edge, in particular the end-face edge of the fabric layer. More preferably, a second fabric strip forms each of the two end-face edges of the fabric layer. An end-face edge of the fabric layer is understood to be the edge that, in the axial direction of the flat material into which the fabric layer is integrated, is located at the end face of the filter element, i.e., in the region of the respective end disk of the filter element. In other words, the end-face edge of the flat material, which is cylindrical in its assembled state, forms the upper edge or the lower edge of the flat material.

[0016] In this area, the fixation of the warp threads is relevant, so this design particularly simplifies the processing of the fabric layer.

[0017] Preferably, several second fabric strips are arranged at intervals, with a first fabric strip positioned between two second fabric strips. This embodiment includes various versions. For example, the two end edges of the fabric layer can each be formed by a second fabric strip, with a first fabric strip positioned between the two second fabric strips. This embodiment is primarily intended to simplify the processing of the fabric layer. It is also possible to provide three or more second fabric strips, with a first fabric strip positioned between each, to form different functional areas of the fabric layer. Furthermore, this embodiment protects an intermediate product of the fabric layer, which is transformed into the final product by appropriate cutting, e.g.,...a layer of tissue with two second tissue strips and a first tissue strip in between.

[0018] The first fabric strip, especially the main fabric, can have a larger surface area than the second fabric strip. Therefore, the flow characteristics of the flat material are primarily determined by the first fabric strip of the fabric layer.

[0019] In a further embodiment, the first fabric strip forms a flow-through area of ​​the corrugated or folded flat material, through which the fluid can flow, wherein the flow-through area has a flow resistance that is smaller than the flow resistance of the second fabric strip.

[0020] In a particularly preferred embodiment, the first weave of the first fabric strip, in particular the main fabric, comprises a twill weave, in particular a double twill weave, in particular a herringbone twill weave, or a satin weave. The twill weave has the advantage that the mechanical strength of the corrugated or folded flat material produced with such a fabric layer is increased, and the risk of damage under alternating pressure loads is reduced. Furthermore, the flat material thus formed exhibits low flow resistance. The combination of a twill weave for the first fabric strip and a plain weave or turn-twill weave for the second fabric strip is particularly preferred. The invention is not limited to this combination but also extends to other combinations of weave types.

[0021] The first fabric strip, in particular the main fabric, and / or the second fabric strip can form a hybrid fabric with first and second threads, wherein the first threads, in particular the warp threads, are made of plastic and the second threads, in particular the weft threads, are made of metal. This extends the service life of the flat material.

[0022] In a preferred embodiment of the filter element, the flat material has a hollow cylindrical shape and is connected to an end plate at at least one end face. A second fabric strip of the same layer is at least partially covered by the end plate. This advantageously ensures that, for example, when the edge threads are fixed, the second fabric strip with the second binding method is not part of the effective surface of the filter element and is therefore not exposed to fluid flow.

[0023] The second fabric strip can be at least partially embedded in the adhesive bed of the end plate and is therefore located in an area of ​​the filter element that is not subject to flow. The disadvantage of the second fabric strip with regard to flow characteristics therefore does not affect the pressure drop of the filter element.

[0024] The claimed filter has a filter element according to the invention, i.e. a filter element with a flat material according to the invention.

[0025] In the inventive method for producing a corrugated or folded flat material of a filter element, a first fabric strip and at least one second fabric strip are woven, the threads of which, in particular weft threads, merge into one another. During weaving, the weaving process changes from a first weave type of the first fabric strip to a second weave type of the second fabric strip. The second weave type differs from the first weave type.

[0026] Furthermore, a functional layer of the flat material is bonded to the fabric layer.

[0027] The invention is explained in more detail below with reference to an exemplary embodiment and the accompanying schematic drawings.

[0028] These show: Fig. 1 a perspective view of a filter element with a partially cut filter bellows or folded flat material; Fig. 2 a perspective view of a fabric layer according to an embodiment of the invention during manufacturing, which is inserted into the filter bellows according to Fig. 1 is integrated; Fig. 3 shows a section of a second tissue strip of the tissue layer according to Fig. 2 , in which the "plain weave" binding type is implemented; Fig. 4 shows a section of the second fabric strip with the "plain weave" binding type according to Fig. 2 and Fig. 5 a section of the first strip of fabric with the weave type "twill weave" according to Fig. 2 .

[0029] In Fig. 1 A filter element is schematically depicted, for example, for use in a hydraulic filter. Use in a hydraulic filter is particularly preferred. It is possible to use the filter element in other filters as well. It comprises a perforated frame or a cylindrical support tube 12, which is radially perforated by a plurality of flow openings 13. In the circumferential direction, the support tube 12 is surrounded by a multi-layered filter bellows 15, which is Fig. 1 For clarity, it is partially shown in the form of an exploded view. The filter bellows 15 can also be described as corrugated or folded flat material. The filter bellows 15 is folded in a star shape by folds 17 running parallel to the longitudinal axis of the support tube 12, such that radially outer fold tips 18 and radially inner fold bases 19 alternate along its circumference.

[0030] The filter bellows 15 specifically comprises a three-layer filter material 22 with a fine filter layer in the form of a nonwoven fabric 24, which, in the flow direction 26 (i.e., radially from the outside to the inside in the illustrated embodiment), is covered on the raw side by a pre-filter nonwoven fabric 27 and on the clean side by a protective nonwoven fabric 28. The nonwoven fabrics can be made, for example, of a plastic or glass fiber material. The invention is not limited to such a filter material but is also suitable for other filter materials intended for filtration, e.g., with more or fewer than three layers.

[0031] In the flow direction 26, the filter material 22 is supported on its clean side by a support fabric 30, which lies flat against the protective fleece 28 of the filter material 22 and is also folded in a star shape. The support fabric 30, in turn, is supported in the flow direction 26 in the area of ​​the fold bases 19 against the support tube 12. On the raw side, i.e., radially outside, a protective fabric 31 is arranged, which lies flat against the pre-filter fleece 27 of the filter material 22 and is also folded in a star shape. The support fabric 30 and the protective fabric 31 are each made from a single layer of fabric according to the exemplary embodiment, which is based on Fig. 2 This will be explained in more detail below. It is possible that only the supporting fabric 30 or only the protective fabric 31 are made from the fabric layer described in more detail below.

[0032] In Fig. 2 Figure 1 shows that the fabric layer according to the embodiment of the invention has a first fabric strip 10. The first fabric strip 10 can also be referred to as the main fabric. The main fabric is characterized in that it enables the main function of the filter element, namely the flow through the filter material 22 required for filtration. Therefore, the first fabric strip 10 has a particularly large effective area. The first fabric strip 10 extends in the longitudinal direction of the fabric layer according to Figure 1. Fig. 2 . In the assembled state, i.e. in the filter element, the first fabric strip 10 extends in the circumferential direction of the filter element.

[0033] The first fabric strip 10 transitions into a second fabric strip 11, which extends essentially parallel to the first fabric strip 10. It is possible that the second fabric strip 11 has an offset of at least one warp thread, in particular of several warp threads. Alternatively, a zigzag pattern of the second fabric strip 11 is possible. Specifically, the weft threads of the first fabric strip 10 transition into the weft threads of the second fabric strip 11. The two fabric strips 10 and 11 thus use the same weft threads and therefore form a uniform or continuous fabric layer that extends in one and the same plane, at least in its manufactured state. When the fabric layer is integrated into the flat material or the filter bellows 15, it forms the same star-shaped contour as the filter material 22. The flat material, and thus the fabric layer, is corrugated or folded.

[0034] As in Fig. 2 As indicated by the hatching, the first fabric strip 10 has a first type of weave, and the second fabric strip 11 has a second type of weave, which differs from the first type of weave. This results in different properties of the fabric layer being established in the areas of the first fabric strip 10 and the second fabric strip 11. For example, the threads of the fabric layer in the area of ​​the second fabric strip 11 can be fixed more firmly by the second type of weave than the threads of the fabric layer in the area of ​​the first fabric strip 10.

[0035] As in Fig. 2 To identify, a different number of first and second tissue strips 10, 11 may be provided. In the example according to Fig. 2 Three first tissue strips 10 and four second tissue strips 11 are provided, with the first tissue strips 10 each extending between two second tissue strips 11.

[0036] In the example according to Fig. 2 The entire tissue layer is cut to create partial tissue layers, each comprising a first tissue strip 10 and two second tissue strips 11 extending along the edges of the tissue layer. In use, the edges of the partial tissue layers form the end faces of the bellows 15, as shown in Fig. 1 to see. In the example according to Fig. 2 Three partial fabric layers are formed. The width of the partial fabric layers can vary. The width depends on the distance between the second fabric strips 11. This has the advantage that the fabric layer can be manufactured for different filter bellows sizes.

[0037] It is also possible to produce a single layer of fabric with several first fabric strips 10 separated by second fabric strips 11, similar to the entire fabric layer before cutting, i.e., the uncut fabric 3. This allows the filter element to have different flow zones with different properties, which are set by the appropriate choice of the respective binding method for the first and second fabric strips 10, 11.

[0038] In the embodiment according to Fig. 2 The main fabric, i.e., the first fabric strip 10, is produced in the "twill weave" weave. The second fabric strips 11 are each produced in the "plain weave" weave.

[0039] Other combinations of weave types are possible. For example, the first weave type of the first fabric strip 10 could be a twill weave or a herringbone weave. It is also possible that the first weave type is a satin weave. The second weave type could be a plain weave or a plain weave, as in Fig. 2 , or include a twisted weave. These second types of weave are characterized by the fact that they fix the warp threads well in the fabric layer (fixing weave).

[0040] An example of a canvas formation (second binding type) is in Fig. 3 and Fig. 4 As shown. In plain weave, the weft thread 32 alternately passes over and under a warp thread 33. The crossings of the weft threads 32 and the warp threads 33 follow a 1:1 pattern. The second fabric strips 11 are characterized by high shear strength. The threads, especially the warp threads of the second fabric strips 11, are well fixed within the fabric structure by the plain weave.

[0041] An example of a twill weave (first type of weave) is in Fig. 5 shown. In contrast to plain weave according to Fig. 4 The weft thread 32 of the first fabric strip 10 passes under two warp threads 33, then over two more warp threads 33, then under two more warp threads 33, and so on. The immediately adjacent weft thread shifts this pattern one position to the side. Weft raises 38 thus extend over two adjacent warp threads; the same applies to weft lowers 39.

[0042] When two layers of the twill-weave fabric come into direct contact with each other in the area of ​​the first fabric strip 10, or in the areas of the first fabric strips 10, through the formation of folds or waves, then thread or filament sections protruding in the outflow direction, in particular warp and weft raises facing each other and intersecting, lie against one another. The total thickness of the twill-weave layers lying against each other through folds or waves is greater than the total thickness of the plain-weave layers lying against each other through folds or waves. Microchannels form between the twill-weave layers lying against each other through folds or waves, which are not affected even by slight relative movement of the two layers, but rather retain their stable shape.

[0043] By combining different types of weave, locally different properties of the fabric layer are set, which, for example in the case of plain weave, significantly reduce the rework effort in the production of the filter elements at the edges of the fabric layer because the edge threads are fixed in the fabric composite.

[0044] In addition, the arrangement of the second tissue strips 11 at the end face edges of the tissue layer, as in Fig. 2 shown, this leads to the areas with the second type of bonding, i.e. the second fabric strips 11, being immersed in the end discs 38, 40 and thus not participating in the effective flow area of ​​the filter element.

[0045] In summary, the fabric layer is not woven continuously in one and the same weave type, such as twill, as in the prior art. Rather, at the points where the fabric layer is later cut, i.e., on defined widths, a strip with a specific number of warp threads is woven in a different weave type, in particular plain weave. The main advantage is that, due to the plain weave at the edge, the edge thread is much better fixed in the fabric than in a pure twill weave because of the more frequent changes, i.e., the more frequent twisting of the thread. As a result, the edge thread is much less likely to jump out of the fabric or be pulled out.

[0046] Within the scope of the invention, the filter element is claimed to have a filter bellows in which at least one layer of fabric according to the exemplary embodiment is integrated. Specifically, the filter bellows contains several layers of material that are folded together to form a star-shaped pattern. One or two of these layers (upstream or downstream) consist of a core fabric that has a positive effect on the performance data and, in particular, the pressure drop of the filter element. Specifically, the first fabric strip 10 is designed in this way. The inherent disadvantage of the fabric optimized with respect to pressure drop is that the edge threads in the twill weave are poorly bound within the fabric, so that during the folding process and subsequent processing steps, such as the singulation of the bellows, the edge threads are not sufficiently held within the fabric structure, resulting in additional rework.

[0047] The body fabric used for the main fabric, or more generally the first strip of fabric with the first weave type, is supplemented by using a second weave type at the edges, or where the fabric is cut into smaller widths after weaving. Specifically, this second weave type is plain weave. Ideally, the number of warp threads woven into the plain weave is chosen to be as low as possible so that this part of the fabric disappears into the adhesive bed of the filter element's end discs and thus does not affect the filter element's performance.

[0048] Additional zones or strips with plain weave can be incorporated between the actual cutting lanes to create more flexible options after weaving, for example, to allow cutting to different widths. Instead of plain weave at the edge, i.e., in the second strip of fabric, other weave types that differ from the primary weave of the fabric can be used at the edge. These weaves hold the edge threads in the fabric much more securely than twill weave. For example, a twist weave is suitable. This eliminates the need for manual rework due to edge threads popping out, resulting in a significant production improvement for filter element manufacturing. Reference symbol list

[0049] 1 Mother roll 2 Roll for cutting 3 Uncut fabric 4 Cutting blade 10 First fabric strip 11 Second fabric strip 12 Support tube 13 Flow openings 14 Clear 15 Filter bellows 16 Clear 17 Pleats 18 Pleat tips 19 Pleat bases 20 Clear 21 Clear 22 Filter material 23 Clear 24 Fleece 25 Clear 26 Flow direction 27 Pre-filter fleece 28 Protective fleece 29 Clear 30 Support fabric 31 Protective fabric 32 Weft thread 33 Warp thread

Claims

1. A flat material for a filter element, wherein the flat material has a corrugated or pleated shape with a plurality of pleats (17) or corrugations running parallel to each other, which form successive pleat or corrugation peaks (18) and pleat or corrugation troughs (19), which are each connected to each other by a pleat flank, wherein the flat material, through which a fluid can flow, has at least one functional layer for removing foreign substances from the fluid, wherein the functional layer is connected to at least one fabric layer which has a first fabric strip (10), in particular a main fabric, and at least one second fabric strip (11), the threads of which, in particular weft threads (32), merge into one another, wherein the first fabric strip (10) has a first type of weave and the second fabric strip (11) has a second type of weave that differs from the first type of weave.

2. The flat material according to claim 1, characterized in that the second fabric strip (11) forms a fixing weave which fixes the threads, in particular warp threads (33), of the first fabric strip (10), wherein the second type of weave of the second fabric strip (11) comprises a linen weave or a leno weave.

3. The flat material according to claim 1 or 2, characterized in that the second fabric strip (11) forms the front-face edge of the fabric layer.

4. The flat material according to any one of the preceding claims, characterized in that a plurality of second fabric strips (11) is arranged spaced apart from one another, wherein a first fabric strip (10) is arranged between two second fabric strips (11) .

5. The flat material according to any one of the preceding claims, characterized in that the first fabric strip (10), in particular the main fabric, has a larger area than the second fabric strip (11).

6. The flat material according to any one of the preceding claims, characterized in that the first fabric strip (10), in particular the main fabric, forms during use a flow region of the corrugated or pleated flat material through which the fluid can flow, wherein the flow region has a flow resistance that is less than the flow resistance of the second fabric strip (11).

7. The flat material according to any one of the preceding claims, characterized in that the first type of weave of the first fabric strip (10), in particular the main fabric, comprises a twill weave, in particular an alternating twill weave, in particular a herringbone twill weave, or an atlas weave.

8. The flat material according to any one of the preceding claims, characterized in that the first fabric strip (10), in particular the main fabric, and / or the second fabric strip (11) form / forms a hybrid fabric with first and second threads, wherein the first threads, in particular warp threads (33), are formed from plastics and the second threads, in particular weft threads (32), are formed from metal.

9. A filter element with a flat material according to claim 1.

10. The filter element according to claim 9, characterized in that the flat material has a hollow cylindrical shape and is connected, on at least one front face, to an end disc, wherein a second fabric strip (11) is at least partially covered by the end disc.

11. The filter element according to claim 10, characterized in that the second fabric strip (11) is at least partially arranged in the adhesive bed of the end disc.

12. A filter, in particular hydraulic filter, with a filter element according to claim 9.

13. A method for producing a flat material for a filter element according to claim 1, in which a functional layer of the flat material is connected to a fabric layer, wherein for producing the fabric layer, in particular a protective fabric (31) and / or supporting fabric (30), a first fabric strip (10) and at least one second fabric strip (11) are woven, the threads of which, in particular weft threads (32), merge into one another, wherein a switch is made during weaving from a first type of weave of the first fabric strip (10) to a second type of weave of the second fabric strip (11), which differs from the first type of weave.