MXPA00005075A - Filter element - Google Patents

Abstract

The invention relates to a filter element, wherein several layers (2, 3, 5;7, 8) made of a filtering medium are joined contiguously in the direction of flow. At least one layer (2;7) made of a filtering medium with high storage capacity and low degree of elimination is arranged on the inflow side and at least one layer (3;8) made of a filtering medium with low storage capacity and high degree of elimination is arranged on the outflow side. Preferably, the inflow filtering medium should be made of a filter paper containing cellulose or of a melt blown material and the outflow filtering medium should be manufactured from a filter paper containing cellulose.

Description

FILTERING ELEMENT STATE OF THE ART The invention relates to a filter element, particularly for filtering liquids, of the type in which a plurality of layers of filter medium are juxtaposed in the direction of circulation and for which there is a degree of particle separation to filter increasing in direction of circulation and a decreasing storage capacity in the same direction of circulation. It is known that in the known filter elements various filter materials are combined together to generate an optimum filtering behavior for the particles to be separated and the circulating liquid. For example, from the German patent DE 44 43 158 Al it is known to use a "meltblown" as a filtering medium in a gas stream together with a support material exclusively intended for stabilization.

Furthermore, from WO 96/34673 it is known that several filter layers of meltblown can be placed on a support layer in a hollow cylindrical filter element. These layers together form a rechargeable filter element. US Pat. No. 5,496,627 and WO 95/17946 disclose the serial arrangement of non-woven filter media of synthetic fibers with stepped filter fineness by increasing the filter fineness of the filter layers in the flow direction. Furthermore, it is reported in US Pat. No. 5,427,597 and WO 96/34673 that several filter layers or only one non-woven filter layer manufactured by the "meltblown" process are arranged on a support layer intended essentially for stabilization. The filter effect of the support layer is negligible in relation to the other layers. The production of synthetic filter fabrics, particularly non-woven meltblown type to produce filters, requires the use of support materials. For this purpose, for example, metallic wire fabrics or cellulose-based filter papers are also used. By using cellulose-based support layers, only filter layers having a substantially lower degree of separation than the synthetic filter layer have been used up to now. The support layer has no influence on the filtration properties of the arrangement as a whole, but occupies a substantial space. Overall, in this known concept only a certain part (for example 30% -50%) of the volume of the total provision for filtering is used.

Problem to be solved The invention has the purpose of producing a filter element of the type mentioned above so that the filtering effect is improved together, by a multilayer structure, and can be maintained for a long period of time.

Advantages of the invention The filter element according to the invention is conveniently intended to solve the problem raised with the features of the main claim. In the filter element according to the invention, several layers of a filter medium are juxtaposed in the direction of circulation, increasing the fineness of the filter in the flow direction with a decreasing dirtiness of the individual layers to improve the total capacity with a certain filter fineness or to improve filter fineness with a given capacity. Conveniently, the functions of folding capacity, support of the synthetic layers and very fine filtration are advantageously integrated into the filter element according to the invention in the cellulose layer arranged on the effluent side. Contrary to the conventional arrangements, according to the invention, the total volume of the filter for the separation of particles is used in an arrangement with increasing filter fineness in the direction of circulation, the filtering layer being based on cellulose and not a filter layer, in particular. synthetic (for example "meltblown") as the filtering layer of maximum fineness. With the invention is also achieved an improvement of the processability and an increase of the mechanical stability for the manufacture of self-supporting filtering elements folded in star, especially for economical manufacturing in rotary folding machines. The advantages of the arrangement according to the invention with respect to the filtration, space utilization and processability capacities are also given when the cellulose fiber also eventually has a larger diameter than the synthetic fibers. In a preferred embodiment of the filter element according to the invention, the above described cooperation of the different degrees of separation and storage capacities of the different layers is achieved because the filtering media of cellulose filter paper disposed on the inflow side and the filtering medium arranged on the effluent side they also consist of a cellulose filter paper. In this case with a suitable corresponding addition of cellulosic fiber in a filter paper the corresponding filtering effect is achieved in the respective layer as indicated above. The cellulose filter papers can also contain a proportion of foreign material up to 50%, in which these foreign materials can be glass or polyester fibers.

In another embodiment, the inflow side filter medium can be a "meltblown", for example of synthetic fibers, and the effluent side filter medium can be a foldable filter paper. The use according to the present invention of the so-called "meltblown" nonwovens as a layer of the filter medium is particularly convenient because they have a high storage capacity for the filtered particles with little fluid dynamic resistance for the material to be filtered. This advantage is achieved by the scarce diameter of the fibers (approximately <2: m) and the large porosity of the "meltblown" nonwoven material. The filtering effect, particularly the degree of separation, increases firstly during use as the filtered particles accumulate. The filter fineness of the inflow side layer is chosen so that by means of this thin layer a sufficiently long usage time of the filter element is achieved. In order to also achieve a high degree of separation of the arrangement as a whole in the initial phase of the use of the filter element, a filtering paper with cellulose additives can also be conveniently used here as a layer on the effluent side. This material has already in the initial phase a high degree of separation of particles to be filtered, although with a lower storage capacity than for a non-woven "meltblown".

As a whole, therefore, with these at least two layers in all the embodiments, a relatively long usage time can be achieved with a high and constant degree of separation of the filter element. Convenient embodiments can be obtained in particular cases by the fact that on the inflow side a "meltblown" nonwoven is used with approximately 15 to 150 g / m2 of weight per unit area and on the effluent side a cellulose filter paper with approximately 50 to 200 g / m2 of weight per unit area. As a raw material for "meltblo n" nonwoven, for example, PP (polypropylene) can be used, especially for non-aggressive liquids, or PES (polyethersulfone), which can also be used for the filtration of fuels or hydraulic oils or lubricants. The high degrees of separation of the finest filter layer are achieved by densification of the fibers during the manufacturing process or by mechanical densification (calendering) of the cellulose layer following the manufacturing process. It is particularly advantageous if the densified cellulose layers, even with very low thickness, have sufficient mechanical stability and therefore a sufficient support capacity of the synthetic filter layer as well as a sufficient mechanical strength of the total of the filter arrangement.

A suitable improvement of the filter element according to the invention is achieved if a third layer of a calendered meltblown is disposed between the filter medium on the inflow side and the filter medium on the effluent side. A convenient embodiment of the filter arrangement according to the invention with the gradient structure described in terms of storage capacity and degree of separation is preferably obtained by the fact that the juxtaposed layers of filter media are folded into a star shape to constitute the filtering element. In particular, the layers of filter media can be welded by ultrasound before, during or during folding or they can be juxtaposed by surface pressing during the folding process, for example in a die-cutting folding machine. The layers can also be glued using an adhesive, it being possible to use an adhesive in the form of a powder or a hotmelt impregnating medium (hot melt.) As an application field for the filter element according to the present invention, for example, filter systems can be used. oil, particularly for a motor vehicle The multi-layer filter elements described above are significantly superior to conventional single-layer filter media in terms of fluid dynamics and capacity, particularly adapted combinations of a few basic elements for the filter elements. here a large spectrum of variation of the filtering properties, so that a longer useful life can be achieved with a certain construction volume, a greater filtering fineness without affecting the time of use and a lower fluid dynamic resistance with relatively simple means. Other suitable embodiments are indicated in the subclaims.

Drawings Exemplary embodiments of the filter element according to the invention are illustrated based on the drawings, in which: Figure 1 represents a sectional view through a filter element with an inflow side layer constituted by a nonwoven "meltblo" n "and a layer on the effluent side of cellulose filter paper. Figure 2 represents a sectional view through the filter element according to Figure 1 with an intermediate layer. Figure 3 represents a sectional view through the filter element with an inflow side layer and an effluent side layer of cellulose filter paper. Figure 4 is a diagram of an example of star folding.

Figure 5 is a diagram of the variation of the degree of separation that depends on the particle load of the filter element.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS Figure 1 shows a section through a filter element 1 with a layer 2 arranged on the inflow side constituted by a meltblown nonwoven and a layer 3 arranged on the effluent side constituted by paper filtering cellulose. The meltblown nonwoven of the layer 2 can be prepared for example with a fibrous material of approximately 15 to 150 g / m2 of weight per unit area, while on the effluent side the layer 3 with cellulosic filter paper can be prepared with approximately 50 to 200 g / m2 of weight per unit area. As the raw material for the meltblown nonwoven, for example, polypropylene, particularly for non-aggressive liquids, or polyethersulfone can be used. In an exemplary embodiment of the filter element according to FIG. 2, a third layer 3 of a calendered meltblown is arranged between the layer 2 arranged on the inflow side and the layer 3 on the effluent side. Another preferred embodiment of a filter element 6 is shown in FIG. 3. In this case, the filter medium on the inflow side consists of a layer 7 of a cellulose filter paper and a layer 8 of cellulose filter paper on the cell side. effluence. In this example of embodiment and with a correspondingly adapted aggregate of cellulosic fibers in a paper filter medium, the corresponding filter effect of the corresponding layer is obtained, as described below. For the preparation of the filter layers of the filter elements 1, 4 or 6 described on the basis of FIGS. 1 to 3, the juxtaposed layers of the filter media are folded into a star shape according to the scheme of FIG. 4 for the formation of the filter element. filter element 9. The layers of filter media can be welded by ultrasound before or during folding, or be joined by gluing or by surface pressing during the folding process, for example in a folding-die-cutting machine. For the clarification of the various filter effects, the curves of the variation of the degree of separation (%) as a function of the particle load (g / m2) of the filter element are shown in a diagram according to FIG. The curve shows, for example, the trace 10 for the layer 2 arranged on the inflow side (see figure 1) constituted by a non-woven "meltblown", the curve 11 the tracing for the layer 3 arranged on the effluence side (see figure). 1) and constituted by a cellulose paper. The curve 12 shows the combined effect of the two layers 2 and 3 according to figure 1. It can be seen from the scheme of figure 5 that at the beginning of the loading with particles a layer 2 of a filter medium is arranged on the inflow side with high storage capacity and low degree of separation for the particles to be separated by filtration, and on the effluent side a layer 3 of a filter medium with low storage capacity and high degree of separation for the particles to be separated by filtration.

Claims (11)

Claims

1. - Filter element, in which a plurality of layers (2, 3, 5, 7, 8) of a filter medium are juxtaposed in the direction of fluid flow for which there is a degree of separation of particles to be separated by increasing filtration in direction of circulation, with decreasing storage capacity in the same direction of circulation, characterized in that the filtering layer (2) arranged on the inflow side is constituted by synthetic fibers and the filtering layer (3; 8) disposed on the effluent side consists of a preponderantly cellulose filter paper. 2.- Filter element, in which a plurality of layers (2, 3, 5, 7, 7, 8) of a filter medium are juxtaposed in the flow direction for which there is a degree of separation of particles to be separated by filtration increasing in the direction of circulation, with decreasing storage capacity in the same direction of circulation, characterized in that the layer (2) arranged on the inflow side consists of a predominantly cellulosic filter paper with a weight per unit area of 50 to 200 g / m 2 and the layer (3) arranged on the effluent side of the filtered liquid consists of a preponderantly cellulosic filter paper with a weight per unit area of 50 to 200 g / m

2.

3. Filter element according to claim 2, characterized in that the layer (2) arranged on the inflow side consists of a preponderantly cellulose filter paper with a weight per unit area of 50 to 200 g / m2 having a unilateral application of medium of impregnation disposed on the effluent side, and the layer (3) disposed on the filtered fluid side is constituted by a preponderantly cellulose filter paper and totally impregnated, with a weight per unit area of 50 to 200 g / m2.

4. Filter element according to claim 1, characterized in that the layer (2) arranged on the inflow side is constituted by a "meltblown" nonwoven with approximately 15 to 150 g / m2 per unit area and the layer (3) arranged on the effluent side of the filtered fluid is constituted by a preferentially cellulose filter paper optionally calendered or densified with a weight per unit area of 50 to 200 g / m2.

5. - Filter element in which three layers (2, 5, 3) of a filter medium are juxtaposed, characterized in that the layer (3) on the effluent side consists of a predominantly cellulosic filter paper usable primarily for the stabilization of the filter element , and all the other layers (2, 5) are non-woven materials constituted by synthetic fibers, these filter layers having a degree of separation of particles to be filtered increasing in the flow direction of the fluid, with a simultaneously decreasing storage capacity.

6. Filter element according to claim 5, characterized in that a third layer (5) of a "meltblown" non-woven fabric optionally calendered is arranged between the inflow side and the filter medium arranged on the effluent side. weight per unit area of 15 to 150 g / m2.

7. - Filter element according to one of the preceding claims, characterized in that the juxtaposed filter means are folded in a star shape for the formation of the filter element (9).

8. - Filter element according to one of the preceding claims, characterized in that the layers (2, 3, 5, 7, 8) of filter media are welded by ultrasound.

9. Filter element according to one of claims 1 to 7, characterized in that the layers (2, 3, 5, 7, 8) of filter media are joined by surface pressure during the folding process.

10. Filter element according to one of claims 1 to 7, characterized in that the layers (2, 3, 5, 7, 8) of filter media are juxtaposed by adhesion, with powdery adhesive or with a hot meltable impregnating medium., or by surface pressure during a folding process.

11. Filter element according to one of the preceding claims, characterized in that one or more of the cellulosic filter layers comprises a proportion of up to 50% of synthetic fibers, particularly polyester or glass fibers. 12, - Filter element according to one of the preceding claims, characterized in that the filter element is applied as a main or secondary filter in an oil or fuel filtration system, particularly for a motor vehicle.