Patent Application
20160279550
The present invention relates to a multi-layered, web-shaped filter material for filter elements for the filtration of gases and/or liquids. The invention additionally relates to a filter element which is produced by means of such a filter material. Finally, the present invention relates to a method and a device for producing such a filter material.
Filtration tasks exist in many technical areas. Of particular importance within the scope of the present application are vehicle applications, i.e. filtration tasks on or in vehicles, such as for example in an air filter, a fuel filter, an oil filter.
In a filter or a filter device, filter elements are employed which each comprise at least one filter body. Here, the filter body is preferably produced from a web-shaped filter material, which for forming the filter body is folded or pleated. Multi-layered filter materials are known in principle for an efficient filtration and long service lives. For realising high degrees of separation for small and smallest contaminations, nanofilters are additionally known. In filtration there exists the general problem that with increasing degree of filtration a flow resistance of the filter material increases as well. If for example a particularly high degree of filtration is aimed at in particular in connection with a nanostructure, a very high flow resistance is generally obtained for the associated filter material. High flow resistances however are disadvantageous since on the one hand they mechanically load the filter element and on the other hand require an adapted periphery if applicable, such as for example increased rates of delivery of pumps and intensified sealing measures.
Filter materials are known for example from U.S. Pat. No. 5,993,501 A, DE 10 2007 027 299 B4, WO 2013/068436 A1 and EP 1 366 791 A1.
The present invention deals with the problem of stating an improved embodiment for a filter material or for a filter element or for a production method and for a production device, which is characterized in particular by a high degree of filtration with comparatively low flow resistance.
According to the invention, this problem is solved through the subjects of the independent claims. Advantageous embodiments are subject of the dependent claims.
The invention is based on the general idea of designing the filter material at least in three layers and to equip said filter material with at least one fleece layer, a cellulose layer and a nanofibre layer arranged between the fleece layer and the cellulose layer. It is proposed, furthermore to equip the nanofibre layer in a thickness direction of the filter material with an increasing fibre thickness and/or with an increasing fibre density. It has been shown that such a configuration results in that with a high degree of filtration a comparatively low flow resistance can be realised. This is explained by the fact that smaller particles are separated only in the depth of the nanofibre layer and not already on the outside, which applies to larger contaminations. In contrast with a conventional nanofibre structure, in which the fibre thickness and the fibre density are continuous in the thickness direction of the fibre material, the contaminations thus are not only deposited on the nanofibre layer on the outside but also in its interior, so that it clogs less severely and less rapidly.
According to an advantageous further development, the fibre thickness and/or the fibre density in the thickness direction of the filter material can increase continuously, preferentially evenly or in steps. A two-step configuration is conceivable in principle here. However, more than two steps are preferably provided or a stepless variation of the fibre thickness and/or fibre density.
Practically, the fibre thickness and/or the fibre density can increase from the fleece layer to the cellulose layer. This can then also be a preferred flow direction of the filter material here.
For example, the fibre thickness within the nanofibre layer can vary in a range from 100 nm to 800 nm.
According to another particularly advantageous embodiment, the nanofibre layer can be formed through a coating of the fleece layer with nanofibres. In this manner, the nanofibre layer is directly formed on the fleece layer. This produces, in particular, a fixed connection between the nanofibre layer and the fleece layer. Additionally or alternatively it can be provided to glue the cellulose layer onto the nanofibre layer by means of an adhesive. In this way, a fixed connection is also realised between the nanofibre layer and the cellulose layer. Preferred is a configuration, in which the nanofibre layer is formed through a coating of the fleece layer with nanofibres and the cellulose layer is glued onto the nanofibre layer by means of an adhesive. Because of this, all three layers are connected in a fixed manner. It has been shown that because of this, shear flows, which are orientated in the plane of the filter material, are avoided, so that substantially only a flow of the filter material transversely to its plane, i.e. in the thickness direction of the filter material is present, which substantially reduces the flow resistance. According to a preferred embodiment, the cellulose layer can be provided with an impregnation at least on a side facing the nanofibre layer. Through the impregnation, a clogging of pores of the cellulose layer in particular can be impeded or prevented.
According to an advantageous further development, the impregnation can be matched to the adhesive and prevent or at least impede the adhesive entering the cellulose layer.
In another advantageous embodiment, the adhesive can be produced on a water base. Additionally or alternatively, the impregnation can be produced on a silicone base or consist of silicone. Water-based adhesive is particularly environmentally compatible and simplifies recycling the filter material. An impregnation on silicone base or of silicone is characterized by a particularly high hydrophobization of the cellulose.
A filter element according to the invention, which is suitable for filtering gases and/or liquids, in particular in vehicle applications, comprises at least one filter body which during the operation of the filter element is subjected to a through-flow of gas and/or liquid, wherein the respective filter body comprises a filter material of the type described above.
To enlarge the available filtration area, the filter material can be pleated, i.e. folded.
Particularly practically, the filter element can be a ring filter element with a ring-shaped filter body or a plate filter element with plate-shaped filter body. Such filter elements can be produced particularly easily in large quantities, as a result of which they are particularly suitable for vehicle applications.
A method according to the invention for producing a multi-layered web-shaped filter material, in particular of the type described above is characterized in that a web-shaped fleece layer is coated on the one side with nanofibres in order to generate a nanofibre layer directly on the fleece layer. Furthermore, a web-shaped cellulose layer is glued to this nanofibre layer. Furthermore, the coating of the fleece layer with nanofibres takes place in such a manner that the resulting nanofibre layer in a thickness direction of the filter material has an increasing fibre thickness and/or an increasing fibre density. As explained, this produces a reduced flow resistance with high filtration effect.
According to an advantageous embodiment, the nanofibres can be electrostatically applied onto the fleece layer in a coating station, wherein in a fibre dispensing device of the coating station there is a spacing between the liquid fibre material and the fleece layer. This means that the fleece layer does not directly come into contact with the liquid fibre material, in particular, an immersing of the fleece layer in the liquid fibre material is avoided. The fleece layer is guided past the liquid fibre material spaced from said liquid fibre material. The transfer of fibre material to the fleece layer is carried out by means of ion currents, which are generated through electrostatic voltages. In order for individual molecules of the fibre material to be better able to detach from the fibre material, a line-shaped or dot-shaped dispensing surface is provided within the fibre dispensing device of the coating station, from which the individual molecules can separate more easily. Such a line-shaped dispensing surface can for example be generated with the help of a roll, which on its bottom side dips into the liquid fibre material and which on its top side forms this line-shaped dispensing surface, which faces the fleece layer. However, preferred is an embodiment in which a kind of conveyor belt is used, which in a conveying direction of the conveyor belt comprises a plurality of web-shaped or rod-shaped dispensing elements, wherein each individual dispensing element defines a line-shaped or respectively dot-shaped dispensing surface or respectively dispensing zone. These dispensing elements are arranged behind one another in the conveying direction of the conveyor belt and are spaced from one another in the conveying direction. On its bottom side, the conveyor belt dips into the liquid fibre material at least in the region of the dispensing elements. On the top side of the conveyor belt, the dispensing elements are then facing the fleece layer, so that on each dispensing element filter material can be dispensed via the respective, line-shaped or respectively dot-shaped dispensing zone.
According to an advantageous further development, the spacing between fleece layer and fibre material or between fleece layer and dispensing surface can increase or decrease in the movement direction of the fleece layer. It has been shown that the spacing between fleece layer and the liquid fibre material or the dispensing zone is decisive for the fibre thickness or fibre density that can be achieved.
In another embodiment, the fleece layer can be moved past a horizontal and flat surface of the filter material with an inclination, as a result of which a continuous change of the spacing between the fleece layer and the fibre material or the respective dispensing surface can be realised. For adjusting the spacings, provision can be optionally made that an inclination of the fleece layer with respect to a horizontal plane is able to be adjusted.
In another embodiment, a plurality of dispensing devices can be provided one after the other in the movement direction of the fleece layer, in which there are different spacings between the fibre material or the respective dispensing zone and the fleece layer. Here it is also conceivable to configure the individual fibre dispensing devices each in the manner of a conveyor belt of the type described above. The individual fibre dispensing devices can be optionally vertical adjustable here, in order to be able to adjust the spacings.
In another advantageous embodiment it can be provided to apply an adhesive onto the cellulose layer and to bring the cellulose layer together with the fleece layer in such a manner that the adhesive connects the cellulose layer to the nanofibre layer.
According to an advantageous further development it can be provided that the web-shaped cellulose layer is provided with an impregnation at least on one side prior to applying the adhesive, wherein the adhesive is then subsequently applied onto the impregnated side of the cellulose layer.
The fleece layer can also be called “non-woven” or “blow-melt”.
A device according to the invention for producing a filter material, in particular of the type described above, comprises at least one fibre dispensing device, which has a conveyor belt with at least two rolls and a tub which is able to be filled with liquid fibre material, into which the conveyor belt dips at least on a bottom side, at least two deflection rollers for guiding a fleece layer above the fibre dispensing device and spaced apart from a top side of the conveyor belt and an ionising device for generating different electrical potentials on the fleece layer and on the fibre dispensing device, such that in the operation of the device, liquid fibre material is transported electrostatically from the conveyor belt to the fleece layer. It has been found that with such a device a nanofibre layer can be applied particularly simply and with reproducible parameters such as density and thickness onto the fleece layer.
According to an advantageous embodiment, the device can be configured so that a spacing between the fleece layer and the respective top side of the conveyor belt varies in the direction of movement of the fleece layer. Hereby, a graduated coating, i.e. a coating with a density varying in the thickness direction, can be applied onto the fleece layer.
Advantageously, said spacing can be adjusted e.g. in that at least one of the deflection rollers is arranged so as to be vertically adjustable. Additionally or alternatively, provision can be made that at least one such fibre dispensing device is arranged so as to be vertically adjustable.
A varying spacing can also be realized in that the rolls are arranged so that the top side of the conveyor belt runs in an inclined manner with respect to a horizontal plane. For this, the rolls can have different diameters and/or can be arranged at different levels, so that they dip into the tub at different depths.
Further important features and advantages of the invention are obtained from the subclaims, from the drawings and from the associated Figure description by means of the drawings.
It is to be understood that the features mentioned above and still to be explained in the following cannot only be used in the respective combination stated but also in other combinations or by themselves without leaving the scope of the present invention.
Preferred exemplary embodiments of the invention are shown in the drawings and are explained in more detail in the following description, wherein same reference characters relate to same or similar or functionally same components.
The drawings show, in each case schematically:
According to
The impregnation 6 is matched to the adhesive 5 in such a manner that the impregnation 6 prevents or at least impedes an entering of the non-dried or non-cured adhesive 5 which is usually applied in liquid form penetrating the cellulose layer 4. For example, the adhesive 5 is produced on a water base so that it solidifies in particular through drying. The impregnation 6 is then practically produced on a silicone base or directly formed through silicone.
In a thickness direction 7 indicated by an arrow, which extends transversely to a web plane 8, in which the filter material 1 lies, the nanofibre layer 3 has an increasing fibre thickness and an increasing fibre density. As a rule, an increasing fibre thickness simultaneously leads to an increasing fibre density, which on its part is accompanied by a reduction of the pore size of the nanofibre layer 3 and thus by an increased filtration effect. An embodiment, in which the fibre thickness increases while the fibre density substantially remains constant or in which the fibre density increases while the fibre thickness substantially remains constant is also conceivable.
The fibre thickness and/or the fibre density can increase in the thickness direction 7 of the filter material 1 steplessly or in steps. With a stepless increase, an even or linear increase can be preferred. With a step increase, two or more steps are conceivable.
Preferentially, the fibre thickness or the fibre density increases from the fleece layer 2 in the direction of the cellulose layer 4. I.e., in this case, against the thickness direction 7 according to
With the help of the filter material 1 shown here, a filter element which is not shown here can be produced, which serves for the filtering of gases and/or liquids and serves for filtering out solid contaminations. To this end, the respective filter element comprises at least one filter body which is produced with the help of such a filter material 1. During the operation of the filter element, this filter body is subjected to the throughflow of the fluid to be cleaned. Practically, the filter material 1 in the filter body is pleated, i.e. folded zig-zag-shaped. In preferred embodiments, the filter element is a ring filter element which is characterized by a ring-shaped filter body, or a plate filter element, which is characterized by a plate-shaped, in particular flat filter body.
In the following, a method for producing a multi-layered, web-shaped filter material 1 is described by means of
Within the scope of the production method, a web-shaped fleece layer 2 is coated on one side with nanofibres, as a result of which a nanofibre layer 3 is generated directly on the fleece layer 2. To this end, the fleece layer 2 is reeled from a fleece layer reel 10, which quasi continuously provides the fleece layer 2. In a coating station 11, the one-sided coating of the fleece layer 2 with nanofibres takes place in order to form the nanofibre layer 3 thereon. In
Furthermore, an adhesive 5 is applied onto a web-shaped cellulose layer 4 in the device 9. To this end, the cellulose layer 4 is unreeled from a cellulose layer reel 12, which quasi continuously provides the cellulose layer 4. In an adhesive application station 13, the adhesive 5 is applied onto a side of the cellulose layer 4. Purely exemplarily, this can take place by means of a transfer roll 14, which at the bottom dips into a tub 15 filled with adhesive and on its top side transfers the adhesive 5 onto the cellulose layer 4.
Practically, the cellulose layer 4 is impregnated prior to applying the adhesive 5. This is carried out in an impregnating station 16, which in a suitable manner provides the cellulose layer 4 with an impregnation 6 at least on the side provided with the adhesive 5. Applying the impregnation 6 can be carried out by dipping the cellulose layer 4 into an impregnating agent bath or by spraying on the impregnating agent.
In a connecting station 17, the fleece layer 2 and the cellulose layer 4 are brought together in such a manner that the adhesive 5 connects the cellulose layer 4 to the nanofibre layer 3. The connecting station 17 in this case is reproduced in a simplified form through two rolls 18, between which the individual layers 2, 3, 4 are guided through, so that the two rolls 18 roll off on each other by way of these layers 2, 3, 4. After the connecting station 17, a heating station 19 can be arranged, which ensures a hardening or drying of the adhesive 5.
Following this, the three-layered filter material 1 can be wound onto a filter material reel 20, which stores the web-shaped filter material 1 in a quasi continuous manner.
According to
In the embodiment shown in
Here, the respective fibre dispensing device 22 is realised with the help of a conveyor belt, which comprises a plurality of linear, rod-shaped or web-shaped dispensing elements 24. The dispensing elements 24 practically extend over the entire width of the respective fleece layer 2 and in the process extend transversely to a movement direction 25 of the fleece layer 2. The dispensing elements 24 in this case also extends transversely to a movement direction 26 of the conveyor belt 23. The conveyor belt 23 is arranged so that it dips into a tub 27 with its bottom side, in which tub the liquid fibre material 21 is stored. Because of this, the dispensing elements 24 are dipped into the liquid fibre material 21. On its top side, the conveyor belt 23 moves outside the liquid fibre material 21 and faces the fleece layer 2. The dispensing elements 24 practically define linear dispensing zones 28, which face the fleece layer 2 and which are spaced from the fleece layer 2. A corresponding spacing is drawn into
The conveyor belt 23 is stretched out and driven by means of at least two rolls 33. In the example of
With the help of an ionising device 30, different electric potentials can be generated on the fleece layer 2 and on the fibre dispensing device 22, as a result of which an electrostatic charge is realised, which finally results in an ion current, which discharges molecules of the fibre material 21 from the dispensing zones 28, transports these in the direction of the fleece layer 2 and causes these to adhere to the fleece layer 2.
In the embodiment shown in
In
In
In the example of
Double arrows 34 in the case of the deflection rollers 32 indicate that optionally at least one of the deflection rollers 32 can be arranged adjustably with regard to its vertical spacing from the fibre dispensing device 22. Preferably, the vertical spacing measured perpendicularly to the horizontal, can be adjusted separately in the two deflection rollers 32. The vertical adjustability of at least one such deflection roller 32 allows an inclination to be adjusted, which the fleece layer 2 has between the deflection rollers 32 with respect to a horizontal plane 36, which is indicated in
In the embodiment shown in
In the embodiment shown in
It is clear that the variants presented here in connection with
| Number | Date | Country | Kind |
|---|---|---|---|
| 2553/DEL/2013 | Aug 2013 | IN | national |
| 10 2013 221 340.9 | Oct 2013 | DE | national |
This application claims priority to India Patent Application No. 2553/DEL/2013, filed Aug. 29, 2013, German Patent Application No. 10 2013 221 340.9, filed Oct. 21, 2013, and International Patent Application No. PCT/EP2014/068215, filed Aug. 28, 2014, all of which are hereby incorporated by reference in their entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2014/068215 | 8/28/2014 | WO | 00 |
