DE102017212826A1 - Liquid filter and tank filter system with a liquid filter - Google Patents

Abstract

The invention relates to a liquid filter (1) for separating particles from a liquid, in particular from fuel or a urea solution. The liquid filter (1) has a first filter medium (10), a second filter medium (20) and a support frame (2) with a support frame wall (3). The support frame wall (3) has a first end face (4) and a second end face (5) facing away from it. The first filter medium (10) is fixed in a fluid-tight manner on the first end face (4), and the second filter medium (20) is fastened in a fluid-tight manner on the second end face (5). The support frame (2), the first filter medium (10) and the second filter medium (20) enclose an inner space (7). The first filter medium (10) has a first passage opening (12), wherein in the interior (7) a first filter element (50) is arranged, which is fluid-conductively connected to the first passage opening (12). The invention further relates to a tank filter system (100) with such a liquid filter (1).

Description

Field of the invention

The invention relates to a liquid filter for separating particles from a liquid, in particular from fuel or a urea solution. The invention further relates to a tank filter system with such a liquid filter.

State of the art

So-called tank filter systems are known from the prior art. In such tank filter systems, a liquid filter is arranged directly in a tank for the liquid to be cleaned. The liquid to be purified may be, for example, fuel such as diesel or gasoline or a urea solution in an SCR system (selective catalytic reduction). Such SCR systems find e.g. Use in the reduction of oxides of nitrogen in the exhaust gas of internal combustion engines. The arrangement of the liquid filter directly in the liquid tank valuable space can be saved for example in motor vehicles.

Such a tank filter system with a liquid filter is for example from the US 2004 / 0144705 A1 known.

Disclosure of the invention

The invention is based on the recognition that for such tank filter systems or liquid filters in such tank filter systems as many parameters as possible should be optimized simultaneously. On the one hand, the filter surface should be as large as possible so that the longest possible service life is achieved until the necessary replacement of the liquid filter. In other words, the filter surface should be designed to remove as many particles as possible from the liquid to be cleaned before a filter medium of the liquid filter is clogged or filled with particles in such a way that there is an unacceptable pressure drop between a raw side (eg the outside). the liquid filter and a clean side (eg an interior) of the liquid filter comes. Furthermore, the production costs for such a liquid filter should be as low as possible. This is preferably effected by the simplest possible and accelerated or rapid production process. Finally, the liquid filter should meet all these parameters with the smallest possible space requirement, since, for example, in motor vehicles the available space for such liquid filter is limited.

It has been found that in conventional liquid filters for tank filtration systems either the service life is insufficient and therefore a relatively short maintenance interval is required or that the space occupied by the liquid filter in the tank takes away valuable volume for the liquid to be purified in the tank - in other words conventional Liquid filters for tank filter systems require a relatively large volume in the tank.

There may therefore be a need to provide a liquid filter for a tank filter system which achieves a long service life and a high filter efficiency with the smallest possible space requirement in the tank and thereby occupies the lowest possible volume and is as simple and inexpensive to produce.

Advantages of the invention

This need can be met by the subject matter of the present invention according to the independent claims. Advantageous embodiments of the present invention are described in the dependent claims.

According to a first aspect of the invention, a liquid filter for separating particles from a liquid is proposed. The liquid to be filtered may be, for example, a fuel such as gasoline or diesel or even an aqueous urea solution. The liquid filter has a first filter medium, a second filter medium and a support frame with a support frame wall. The support frame wall has a first end face and a second end face facing away from it. The first filter medium is fixed in a fluid-tight manner on the first end face, and the second filter medium is fastened in a fluid-tight manner on the second end face. The support frame, the first filter medium and the second filter medium enclose an interior space. The first filter medium has a first passage opening, wherein in the interior a first filter element is arranged, which is fluid-conductively connected to the first passage opening.

As a result of the proposed embodiment, the available filter surface is considerably increased by simple means, in that the interior space is used in order to arrange a filter element, namely the first filter element, which is additional to the first filter medium and the second filter medium. Thus, no volume or space is lost in the tank, since the first filter element in the interior of first filter medium, second filter medium and support frame is arranged. The liquid filter thus formed can also be produced easily and is therefore inexpensive to produce.

For the purposes of this application, the term "enclosing an interior" in particular means a fluid-tight closure relative to one External space of the liquid filter in the sense that liquid from the outer space (eg the raw side) can only from this outer space in the interior (eg the clean side of the liquid filter) can pass when it passes either through the first filter medium or through the second filter medium. Of course, liquid can also enter into the interior as it passes through the first passage opening, passes from there into the first filter element and passes through the first filter element into the interior when it passes through. In this case, particles present in the liquid are deposited either on the first filter medium, on the second filter medium or on the first filter element, so that the liquid passing through into the interior is likewise cleaned.

For the purposes of this application, the first passage opening provided in the first filter medium is not to be regarded as a microscopic pore through which liquid can enter or pass. Rather, this first passage opening is so large that unfiltered liquid can enter through the passage opening into the first filter element.

In this case, the liquid filter can be designed, for example, such that the first through-opening makes up at least 0.5% of the area of the first filter medium facing the interior and at most 10% of the area of the first filter element facing the interior. For example, the passage opening may have a diameter of at least 0.5 mm and at most 50 mm. The passage opening may e.g. circular, oval or even formed with a substantially rectangular cross-section, it may also be formed in the shape of a plurality of slots. For example, a length of the cross section of the passage opening may be at least 10 mm and a width of the cross section of the passage opening may be at least 0.5 mm.

The area of the first filter medium is to be understood as the sum of the areas of the first filter medium as such and the area of the passage opening. It is not necessary to focus on a fractal, microscopic surface.

Furthermore, it can be provided, for example, that a projection of the first filter element onto the first filter medium along a surface normal of the first filter medium covers more than 50% of the area of the first filter medium within the boundary of the support frame. In other words, the shadow cast of the first filter element covers more than 50% of the area of the first filter medium. Preferably, more than 70% of the area and very particularly preferably more than 85% of the area is covered.

This causes a particularly large increase in the active filter area.

The first filter medium and the second filter medium may, for example, be arranged substantially parallel to one another. In other words, the support frame wall has substantially the same height everywhere. However, other embodiments are conceivable.

It may be provided that the first filter medium on the first end face and / or the second filter medium on the second end face are fastened in a fluid-tight manner by a friction welding process or a laser welding process. Alternatively or additionally, it can be provided that the first filter medium and / or the second filter medium are connected in an injection molding process in each case with the associated end faces of the support frame wall. In this case, for example, the relevant filter medium act as an insert part of an injection molding system, wherein the support frame is molded from a plastic.

The liquid filter may have an outlet for the purified liquid in the interior. For this purpose, a fluid-conducting channel arranged between the first end side and the second end side can be arranged in the support frame wall. By way of example, the fluid-conducting channel serving as a fluid outlet may have a cross section which is at most 10% of the area of the first filter medium, preferably at most 5% of the area of the first filter medium.

In principle, the liquid flow can also be reversed. In this case, the interior is the raw side and the liquid is cleaned when passing through the first or second filter medium or through the first filter element and thus reaches the outside of the liquid filter, which then constitutes a clean side. The fluid-conducting channel described above is then an inlet for unpurified liquid.

In a further development, it is provided that the first filter medium is formed flat.

Alternatively or additionally, it may be provided that the second filter medium is formed flat.

In this context, planar formation is to be understood as meaning an aspect ratio between the thickness of the first and / or second filter medium relative to an extent of the respective filter medium in the plane which is at least 1: 5 or 1:10, preferably at least 1:20 or even more preferably at least 1:30. For example, the first filter medium and / or the second filter medium in the Form a thin filter membrane with a layer thickness in the range of 5 microns to 3000 microns, preferably from 1000 microns to 2000 microns, for example, be formed with a layer thickness of 1500 microns. In this case, the first and / or second filter medium may be formed from a single layer. The first filter medium and / or the second filter medium may be formed, for example, from a plastic membrane with a pore size of less than 200 microns, for example in the range of 5 .mu.m to 100 .mu.m or have such a membrane, preferably with a pore size of 5 .mu.m to 20 .mu.m , However, it is also possible for the first and / or second filter medium to be constructed from a plurality of layers, for example from a fabric layer with a layer thickness between 100 and 400 μm, which, for example, faces the raw side. Another layer which may be formed as a filter fleece or filter felt or as a membrane and has a layer thickness between 800μm and 1500μm, and a pore size of eg 5μm to 100μm, preferably from 5μm to 20μm. As well as another layer, which faces eg the clean side and may be formed as a so-called spunbound layer, in the manner of an endless filament made of a plastic and has a layer thickness of 50 .mu.m to 800 .mu.m. Preferred materials include plastic, for example polyamide, for example PA6, PA6.6 or polypropylene (PP) or polyethylene (PE).

By such a configuration of the first filter medium and / or the second filter medium, the liquid filter can advantageously be particularly space-saving and compact build and is particularly easy to produce. Thus, the first and / or second filter medium may be e.g. be connected to the support frame by means of an injection molding process or by a welding process. Furthermore, a sufficiently large interior space for arranging the first filter element is formed in this way.

In a further development, it is provided that the first filter element is designed in the form of a pocket, wherein the first filter element has a third filter medium.

The third filter medium may be formed flat and be formed for example in the form of a thin membrane. As a result, the active filter surface is particularly advantageous increases and extends the life. Particularly advantageously, the first, second and third filter medium are formed flat.

Characterized in that the first filter medium is formed in the form of a pocket, advantageously a particularly flexible shape is effected. In this way, the first filter element can adapt well to the shape of the interior. In particular, the shape of a pocket causes no further components, for example a housing, to be necessary in order to allow the first filter element to act. In contrast, for example, to a star filter insert of a conventional fuel filter, the raw side for the liquid is arranged in the bag-like interior of the bag, for example, which enters the interior volume of the bag through the first through-opening. The cleaning of the liquid then takes place simply by the passage of the liquid through the third filter medium.

The first filter element may advantageously be formed in such a way that it predominantly, i. at least 50%, preferably at least 70% and most preferably at least 90% is formed by the third filter medium. For example, the first filter element may have a filter element frame, which is covered on both sides by the third filter medium.

In a further development, it is provided that the first filter element is spaced from the surface of the first filter medium facing the interior. This advantageously ensures that the largest possible effective filter area is provided. Because of the spacing, both the first filter medium and the surface of the first filter element lying opposite it are both effective as a filter surface. For the purposes of the present application, it is to be understood that the region of the first passage opening, on which the first filter element is arranged, is not spaced from the first filter medium, since the connection from the first filter medium to the first filter element occurs here.

The spacing may be, for example, at least 5 times the thickness of the first filter medium, preferably at least 50 times the thickness of the first filter medium, and most preferably at least 100 times the thickness of the first filter medium. Alternatively or additionally, the spacing may be at least 0.5 mm, preferably at least 1 mm and most preferably at least 3 mm. Thus, the purified liquid can advantageously flow off particularly easily, so that all filter surfaces of the filter media are flowed through as uniformly as possible.

In a further development it can be provided that a support structure is provided in the interior of the first filter element. This advantageously has the effect that the first filter element always has a sufficiently large internal volume which can not collapse.

Alternatively or additionally, a spacer element may be arranged between the first filter element or the third filter medium on the one side and the first filter medium on the other side. The spacer can eg as Plastic element may be formed with a corrugated structure or with spacer ribs. By this development is advantageously effected that always a certain spacing between the first filter element and the first filter medium is reached. This ensures that the filter surface is always maintained for cleaning the liquid to be cleaned and is not reduced by a mechanical contact between the filter media. It can also be advantageously ensured that a sufficiently large gap for the flow of purified liquid between the mutually facing surfaces of the filter media remains.

In a further development it can be provided that the support structure has at least one support element, which runs essentially parallel to the first filter medium. Arranged on the support element is a plurality of ribs which project from the support element in the direction of the first filter medium and / or in the direction of the second filter medium.

This advantageously has the effect that the support structure inside the first filter element can assume the role of a kind of spacer. As a result of the plurality of ribs, as far as possible throughout the area of the first filter element, the first filter element or the third filter medium of the first filter element does not collapse, and in this way the active filter surface is always maintained.

In a further development, it is provided that the first filter element is detachably fastened to the first passage opening as a separate element from the first filter medium.

For example, the term detachable means that the first filter element can be removed from the first filter medium in a non-destructive manner. For example, the first filter element may be fastened by a clip connection or a screw connection to the first filter medium or the first through-opening of the first filter medium.

This advantageously allows a particularly simple production process and a particularly simple maintenance.

In a further development, it is provided that the first filter element is fixed inextricably attached to the first passage opening. For example, the first filter element may initially be present as a separate element from the first filter medium and, for example, be welded to the first through-opening during the manufacturing process of the liquid filter. As a result, a particularly reliable and secure fluid-tight connection between the first filter element and the first passage opening is possible.

In a further development it can be provided that the second filter medium has a second through-opening, wherein in the interior a second filter element is arranged, which is fluid-conductively connected to the second through-opening. As a result, a further enlargement of the active filter surface is effected at the same space requirement of the liquid filter advantageous. In this way, the service life is advantageously increased and / or for the same service life, the volume or the space of the liquid filter can be reduced.

According to a second aspect of the invention, a tank filter system is proposed. The tank filter system in this case has a liquid filter according to the above description. Such a tank filtration system is advantageous particularly compact, has a long service life and can be particularly simple and inexpensive to produce.

drawings

Other features and advantages of the present invention will become apparent to those skilled in the art from the following description of exemplary embodiments, which are not to be construed as limiting the invention with reference to the accompanying drawings.

• 1: Einen schematischen Querschnitt eines Tankfiltersystems gemäß der Erfindung;
• 2a-2c: verschiedene perspektivische Ansichten eines Flüssigkeitsfilters gemäß der Erfindung;
• 3: einen schematischen Querschnitt durch den Flüssigkeitsfilter aus den 2a-2c;
• 4: ein weiteres Ausführungsbeispiel eines Flüssigkeitsfilters in einem schematischen Querschnitt;
• 5: einen Querschnitt eines weiteren Ausführungsbeispiels eines Flüssigkeitsfilters;
• 6: einen Querschnitt eines weiteren Ausführungsbeispiels eines Flüssigkeitsfilters.

Show it

• 1 : A schematic cross section of a tank filter system according to the invention;
• 2a-2c various perspective views of a liquid filter according to the invention;
• 3 a schematic cross section through the liquid filter from the 2a-2c ;
• 4 a further embodiment of a liquid filter in a schematic cross section;
• 5 a cross section of another embodiment of a liquid filter;
• 6 a cross section of another embodiment of a liquid filter.

1 represents a tank filtration system 100 dar. The tank filter system 100 has a tank 102 for a liquid 104 on. At the liquid 104 For example, it may be a fuel, such as diesel or gasoline. It is also possible that the liquid 104 an (aqueous) urea solution, for example, for an SCR system for the exhaust aftertreatment of an internal combustion engine is. The direction of gravity g is indicated by an arrow and refers to a normal installation position of the liquid filter 1 in the tank 102 ,

The liquid 104 in the tank 102 is unfiltered, so it is in the tank 102 an outdoor space 103 of the tank filter system 100 before, being the outside space 103 a raw side with unfiltered liquid 104 can represent. The Tank 102 continues to show a breakthrough 105 through which purified liquid the tank 102 can leave. The Tank 102 is from a tank exterior 106 of the tank 102 surround. The Tank 102 also has a liquid filter in its interior 1 on. The liquid filter 1 is designed to remove particles from the liquid 104 deposit. The liquid filter 1 is from the outside space 103 surround, which is the raw side of the liquid filter 1 can represent. The liquid filter 1 has a first filter medium 10 , a second filter medium 20 as well as a supporting frame 2 with a supporting frame wall 3 on. The supporting frame wall 3 has a first end face 4 and a second end facing away from it 5 on. The first filter medium 10 is for example by a friction welding process, a laser welding process or by an injection molding process on the first front page 4 attached fluid-tight. The person skilled in the art is also familiar with other material fastening options, for example gluing. The second filter medium 20 is in an analogous manner on the second end face 5 attached fluid-tight. This enclosing the support frame 2 , the first filter medium 10 and the second filter medium 20 an interior 7 which serves as a clean side. The first filter medium 10 has a first passage opening 12 on, being in the interior 7 a first filter element 50 is arranged, which fluid-conductively with the first passage opening 12 connected is.

In 1 is further to recognize, like the liquid 104 from the tank 102 along the arrows from the outside space 103 (here from the raw side) in the tank 102 through the first filter medium 10 and through the second filter medium 20 in the interior 7 of the liquid filter 1 entry. The interior 7 Liquid is thus cleaned of particles and is thus on the clean side of the liquid filter 1 , Furthermore, liquid can pass through the first passage opening 12 inside 51 of the first filter element 50 enter. The first filter element 50 has a third filter medium 30 on and is formed, for example, in the form of a bag. Here is the third filter medium 30 or the first filter element 50 from the first filter medium 10 spaced. The first filter element 50 or the third filter medium 30 is also from the second filter medium 20 spaced. In this way, liquid can also through the first passage opening 12 inside 51 of the first filter element 50 enter and from there through the third filter medium 30 through, in the figure up and down, to the right and to the left, into the interior 7 of the liquid filter 1 kick, so to the clean side. Particles which are in the liquid 104 are contained inside it 51 of the first filter element 50 from third filter medium 30 retained.

The first filter medium 10 and the second filter medium 20 are arranged substantially parallel to each other. The first filter medium 10 and the second filter medium 20 may be formed, for example, in the form of thin membranes with a planar extension or as a filter fleece. Also the third filter medium 30 may be formed in the form of a thin filter membrane or in the form of a filter fleece. First and second filter media 10 . 20 Both can be the same design, for example, single-layer or multi-layered. They may have the same thickness, for example 10μm to 3000μm, preferably 1000μm to 2000μm. They may also have the same pore size, for example 5 .mu.m to 100 .mu.m, preferably 10 .mu.m to 20 .mu.m (see, for example, by way of example only) 4 and 6 ). You can, however, as in the 1 (and also in 3 and 5 ) is merely exemplified, also different materials and / or different thicknesses and / or pore sizes. The selected thicknesses and pore sizes may be in the ranges given above and below, but may be different. For example, one filter medium may have a thickness of 1000 .mu.m, the other a thickness of 1500 .mu.m. Also, one filter medium may have a pore size of eg 5 .mu.m to 10 .mu.m and the other a pore size of 10 .mu.m to 15 .mu.m. Likewise, the third filter medium 30 equal to the first and / or second filter media 10 . 20 be educated. However, it is also possible that the third filter medium from the two filter media 10 . 20 is different.

The third filter medium 30 can be designed in different forms. So it is possible, for example, that the third filter medium 30 is integrally formed and has only one opening, with which it at the passage opening 12 is attached.

• ■ einstückiges drittes Filtermedium 30 ohne Rahmen 31 und Verbindungsnaht 32;
• ■ aus erstem und zweitem Teil 31a, 30b gebildetes drittes Filtermedium 30 unter Verwendung des Rahmens 31;
• ■ aus erstem und zweitem Teil 31a, 30b gebildetes drittes Filtermedium 30 unter Verwendung der Verbindungsnaht 32, jedoch ohne Rahmen 31

jeweils voneinander separate Ausführungsformen sein können. Dies gilt auch für die Darstellung in den weiteren Figuren.Alternatively, the third filter medium 30 from a first part 30a (In the figure, the first filter medium 10 facing) and a second part 30b (In the figure, the second filter medium 20 be formed). In this case, the first part 30a and the second part 30b be the same. They can be used to form a fluid-tight bag on a frame 31 be attached fluid-tight, eg welded or glued. In an alternative embodiment, the first part 30a and the second part 30b also cohesively to one another at a connecting seam 32 be connected, for example by a weld. In this case, therefore, the two parts 30a . 30b For example, at their outer edges fluid-tight directly connected to each other, for example glued or welded. In the figure are the frame 31 and the immediate one seam 32 both shown simultaneously. It is understood that each of the embodiments

• ■ one-piece third filter medium 30 without frame 31 and seam 32 ;
• ■ from the first and second part 31a . 30b formed third filter medium 30 using the frame 31 ;
• ■ from the first and second part 31a . 30b formed third filter medium 30 using the seam 32 but without frame 31

may each be separate embodiments. This also applies to the representation in the other figures.

In the supporting frame wall 3 is between the first end face 4 and the second end face 5 a fluid-conducting channel 6 arranged for the discharge of the purified liquid from the interior 7 and from the tank 102 suitable is. On the fluid-conducting channel 6 is on the outside of the liquid filter 1 a filter outlet 8th arranged in the form of a channel, which fluid-conducting with the fluid-conducting channel 6 is connected and through the breakthrough 105 of the tank 102 leads through. Through the filter outlet 8th can thus purified liquid from the tank 102 through the liquid filter 1 be removed through. The thus purified liquid can be supplied, for example, to an internal combustion engine or an exhaust aftertreatment system.

To the entry of liquid 104 from the tank 102 through the filter media 10 . 20 . 30 through, can at the filter outlet 8th a negative pressure, for example by a pump on an internal combustion engine or an exhaust aftertreatment system, are generated.

In principle, it is of course conceivable that the liquid filter 1 is also operated in the reverse direction, ie through the filter outlet 8th uncleaned liquid in the interior 7 of the liquid filter 1 is initiated and then from the interior 7 through the filter media 10 . 20 . 30 passes through into the outer space of the liquid filter. The filter outlet 8th In this case, of course, it functions as a filter inlet for introducing liquid into the liquid filter 1 ,

In the 2a and 2 B is a perspective view of a liquid filter 1 shown. 2a shows a view of the second filter medium 20 . 2 B a view of the first filter medium 10 , The different position of the views can be read off the arrow with the reference symbol "g" for the direction of gravity. In this case, the direction of gravity g refers to a normal installation position of the liquid filter 1 in the tank 102 , In 2 B is the first through hole 12 in the first filter medium 10 to recognize. It can be clearly seen that it is the first through hole 12 not just a pore in the first filter medium 10 but an opening which, for example, at least 2 mm in diameter, preferably at least 8 mm in diameter, so that uncleaned fluid through the first passage opening 12 in the first filter element 50 , which is not shown here, can get.

2c shows the view 2a , where here the second filter medium 20 is omitted, the arrangement of the first filter element 50 in the interior 7 of the liquid filter 1 to show.

The first filter element 50 has a filter element frame 31 on which approximately midway between a second filter medium 20 facing top of the second part 30b of the third filter medium 30 and one of the first filter media 10 facing lower side (first part 30a , not visible) of the third filter medium 30 is arranged. The third filter medium 30 can eg on end faces of the filter element frame 31 be welded or in an injection molding process with the filter element frame 31 be connected fluid-tight. However, it is also possible that the first part 30a and the second part 30b of the third filter medium 30 at a connection seam 32 are directly connected. In this case, the frame is 31 not mandatory. It is also possible that the third filter medium 30 is integrally formed. The raw side facing surface of the first filter element 50 may be more than 50%, preferably more than 70% and most preferably more than 90% by the third filter medium 30 or its first and second part 30a . 30b be formed.

In the 2c is also the fluid-conducting channel 6 in the supporting frame wall 3 to recognize which the interior 7 of the liquid filter 1 ie the clean side, with the outlet 8th combines.

The supporting frame 2 of the liquid filter 1 is in the 2a to 2c formed banana-shaped curved. In this way it can be adapted to a tank shape very well.

2c shows that the first filter element 50 in terms of area, most of the interior 7 facing surface of the first filter medium 10 covered, preferably at least 50%, more preferably at least 70% and most preferably at least 85%. In this way, a particularly large additional filter surface is created.

3 shows a cross section through the liquid filter of the 2a-2c , At the inside 51 of the first filter element 50 lies the unfiltered liquid 104 , ie the raw side, in front and the interior 7 of the liquid filter 1 represents the clean side. The raw side and the clean side are shown schematically on the basis of the different hatchings.

Furthermore, it can be seen that the first filter element 50 or the third filter medium 30 by a distance D from the first filter medium 10 is spaced. The distance D is for example at least 25% of the thickness D1 of the first filter medium 10 , preferably at least the thickness D1 of the first filter medium 10 and most preferably at least 3 times the thickness D1 or at least 5 times or even at least 10 times the thickness D1 of the first filter medium 10 , In absolute values, the distance D may be, for example, at least 0.3 mm, preferably at least 0.5 mm or at least 1 mm and very particularly preferably at least 3 mm or at least 6 mm. This ensures a particularly high filtration efficiency and a uniform drainage of the purified liquid. It should be noted that in 3 the first thickness D1 of the first filter medium 10 as well as the second thickness D2 of the second filter medium 20 and the third thickness D3 of the third filter medium 30 are shown exaggerated. In one embodiment, the three thicknesses D1 . D2 . D3 through the execution of the filter media 10 . 20 . 30 as thin filter membranes, for example, a maximum of 100 microns or a maximum of 400 microns thick. In another embodiment, the three thicknesses D1 . D2 . D3 the three filter media 10 . 20 . 30 in the range of 1000μm to 3000μm, with the three filter media 10 . 20 . 30 also be multi-layered. A height H of the supporting frame wall 3 (between the front sides 4 . 5 on the other hand, for example, is at least 5 mm, preferably at least 8 mm, and very particularly preferably at least 10 mm. For example, the height of the supporting frame wall is 3 about 10mm or about 20mm and the three thicknesses D1 . D2 . D3 each amount to about 1500μm.

Also, the first filter element 50 from the second filter medium 20 spaced. The distance between the first filter element 50 and the second filter medium may for example be at least as large as the distance D between the first filter element 50 and the first filter medium 10 ,

Furthermore, in 3 to recognize that a first surface A1 of the first filter medium 10 from the in 3 only one dimension is visible, only slightly larger than a second surface A2 of the first filter element 50 , where the second surface A2 through a projection of the first filter element 10 along a surface normal N of the first filter medium 10 on the first filter medium 10 results, in the manner of a shadow cast. Also from the second area A2 Here, only one direction or dimension is given. By comparing with 2c However, it becomes clear that the first filter element 50 at least 50%, preferably at least 70% of the first filter medium 10 and most preferably at least 85% of the first filter medium 10 covered.

4 shows a further embodiment of the liquid filter. This is inside 51 of the first filter element 50 a support structure 70 intended. The support structure 70 is by a support element 71 with a plurality of ribs disposed thereon 72 educated. The support element 71 extends substantially parallel to the first filter medium 10 and the plurality of ribs protrude from the support member 71 transverse towards the first filter medium 10 and / or to the second filter medium 20 from. By providing the support structure 70 This prevents the majority from the third filter medium 30 formed first filter element 50 collapses during operation and thus reduces the active filter area in an undesirable manner.

Furthermore, between the first filter medium 10 and the first filter element 50 a spacer element 75 arranged. This can be formed for example of a corrugated plastic. In principle, it is possible that in individual embodiments, either only one spacer element 75 is provided or only a support structure 70 , spacer 75 and support structure 70 always cause the additional filter surface of the first filter element 50 is available and the filter surface is not due to the contact or a superimposition of the filter media 10 . 20 . 30 reduced.

5 shows a further embodiment of the liquid filter 1 , In this embodiment, the first filter element 50 in contrast to the preceding embodiments by a releasable connection with the first passage opening 12 connected. In the embodiments of the 2 . 3 and 4 is the first filter element 50 for example, by a welding process at the transition from the first through hole 12 to the first filter element 50 insoluble, ie only by means of a destruction of the structure, on the first filter medium 10 attached. In the present 5 are on the other hand lanyards 35 provided, for example in the form of clips or a clip connection 36 or a screw thread or a screw connection 37 , By means of these connecting means 35 . 36 . 37 can be the first filter element 50 for example, at the edge of the first passage opening 12 be attached fluid-tight. For example, so first the first filter medium 10 with the first filter element 50 be connected and in the supporting frame 2 to be ordered. Subsequently, for example, the second filter medium 20 on the support frame 2 be attached. Also, a first attachment of the second filter medium 20 on the support frame 2 and then inserting the first filter medium 10 attached first filter element 50 in the interior 7 is conceivable.

6 shows a further embodiment of the liquid filter 1 , In this case, next to the first filter element 50 , which at the first passage opening 12 of the first filter medium 10 is arranged, a similar second filter element 60 at one in the second filter medium 20 provided second passage opening 22 intended. The second passage opening 22 can analogous to the first through hole 12 be educated. The second filter element 60 can be analogous to the first filter element 50 be educated. So can the second filter element 60 a fourth filter medium 40 have or include, for example, analogous to the first, second or third filter medium 10 . 20 . 30 is formed in the form of a thin membrane or a filter fleece. The fourth filter medium 40 can be single-layered or multi-layered. It may be formed in one piece or it may consist of a first part 40a and a second part 40b be formed, wherein first and second part 40a . 40b the fourth filter medium, for example on a frame 41 can be attached fluid-tight or but first and second part 40a . 40b are directly adjacent to each other at a joint seam 42 held together fluid-tight. The second filter element 60 can be analogous to the first filter element 50 also be formed, for example, bag-shaped or bag-like. The fourth filter medium 40 can be a fourth thickness D4 that are similar to the thicknesses D1 . D2 . D3 the other three filter media 10 . 20 . 30 is trained. It is understood that the fourth filter medium 40 also from the materials of the other filter media 10 . 20 . 30 can be different. The first and second filter element 50 . 60 are each at the two passage openings 12 . 22 attached. Preferably, the two filter elements are prior to completion of the liquid filter 1 from the first and second filter media 10 . 20 separate elements.

The tank filter system 100 or the liquid filter 1 For example, they are suitable for the filtration of fuels such as diesel or gasoline and in particular for liquids used in SCR systems, eg aqueous urea solution. Basically, the tank filter system 100 also be suitable for the filtration of water.

Claims (10)

Liquid filter for separating particles from a liquid, in particular from fuel or a urea solution, comprising: a first filter medium (10), a second filter medium (20), a support frame (2) with a support frame wall (3), wherein the support frame wall (3) has a first end face (4) and a second end face (5) facing away from it, wherein the first filter medium (10) on the first end face (4) is fixed fluid-tight, wherein the second filter medium (20) on the second end face (5) is fixed fluid-tight, wherein the support frame (2), the first filter medium (10) and the second filter medium (20) enclose an internal space (7), wherein the first filter medium (10) has a first passage opening (12), wherein in the interior (7) a first filter element (50) is arranged, which is fluid-conductively connected to the first passage opening (12). Liquid filter according to one of the preceding claims, wherein the first filter medium (10) and / or the second filter medium (20) are formed flat. Liquid filter according to one of the preceding claims, wherein the first filter element (50) is designed in the form of a pocket, wherein the first filter element (50) has a third filter medium (30). Liquid filter according to one of the preceding claims, wherein the first filter element (50) from the interior (7) facing surface of the first filter medium (10) is spaced. Liquid filter according to one of the preceding claims, wherein a support structure (70) is provided in the interior (51) of the first filter element (50). A liquid filter according to the preceding claim, wherein the support structure (70) comprises at least one support member (71) substantially parallel to the first filter medium (10), wherein on the support member (71) a plurality of ribs (72) are arranged projecting from the support element (71) in the direction of the first filter medium (10) and / or towards the second filter medium (20). Liquid filter according to one of the preceding claims, wherein the first filter element (50) as a separate element from the first filter medium (10) releasably secured to the first passage opening (12). Liquid filter according to one of Claims 1 to 6 , wherein the first filter element (50) on the first passage opening (12) is permanently attached, in particular welded. Liquid filter according to one of the preceding claims, wherein the second filter medium (20) has a second passage opening (22), wherein in the interior (7) a second filter element (60) is arranged, which is fluid-conductively connected to the second passage opening (22). Tank filter system for a motor vehicle, wherein the tank filter system (100) comprises a liquid filter (1) according to one of the preceding claims.

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