EP4355189A2

EP4355189A2 - Microplastic filter for washing machine

Info

Publication number: EP4355189A2
Application number: EP22733565.0A
Authority: EP
Inventors: Andreas Stephan; Henning TILLMANNS; Marcus Wegmann; Gunter MATHY; Markus LÜERSMANN; Tom Klaver; Martin Heitjans
Original assignee: Hengst SE and Co KG
Current assignee: Hengst SE and Co KG
Priority date: 2021-06-15
Filing date: 2022-06-08
Publication date: 2024-04-24
Also published as: WO2022263250A3; US20240229338A9; US20240133111A1; DE102021115442A1; WO2022263250A2

Abstract

The invention relates to a microplastic filter, fluid filter (1) for short, for a washing machine, comprising a filter housing (10), a first filter screen (21), a second filter screen (22) of an inflow opening (16) and an outflow opening (17), wherein the inflow (16) and the outflow (17) communicate with each other through the first filter screen (21), and the first filter chamber (25) has a retentate outlet. The microplastic filter is particularly simple to manage if the second filter screen (22) is arranged in a cavity (15) of the filter housing (10), the inflow (16) and the outflow (17) communicate with each other through the second filter screen, and the retentate outlet is arranged on the inflow side of the second filter screen (22).

Description

Microplastic filter for washing machine

technical field

The invention relates to a fluid filter, for example a microplastic filter for removing microplastics from a fluid to be filtered, which is typically the waste water from a textile washing machine. The fluid filter has a filter housing, a first filter screen, a second filter screen, an inlet opening and an outlet opening. The filter housing forms a cavity. The fluid can flow into the cavity through an inlet opening of the housing and can flow out of the cavity and thus out of the housing through an outlet opening. The first filter screen is arranged in the cavity and at least partially defines at least one first filter space. The inlet and outlet are connected to each other in fluid communication via the first filter screen. In addition, the first filter room has a retentate outlet.

State of the art Microplastics are increasingly found in nature, are not degraded there or not degraded quickly enough and have a negative impact on the fauna, especially in the seas, because microplastics get into the food chain there. As a rule, microplastics are plastic particles with dimensions smaller than 5mm. Fibers, fiber segments and other plastic particles washed out of clothing when washing clothes contribute to the microplastic pollution of water bodies. The fiber length of such washed-out microplastic particles is typically between about 100 μm and 800 μm. the fiber diameter is typically significantly smaller, around a factor of 30. Flaky textile components with edge lengths well below 1mm are also released, which are also referred to as microplastics. A fluid filter for filtering out fibers from washing machine waste water is known from published application DE 102016004326 A1. The waste water flows through an inlet opening into a filter housing in which a first filter screen is arranged. The waste water flows through the first filter screen and the filtrate flows out of a cavity formed by the filter housing through a drain opening. The textile fibers remain caught in a first filter screen. However, the textile fibers are kept suspended by an agitator in order to prevent clogging, ie clogging of the first filter screen. After the washing process, a concentrated textile fiber suspension can then be drained from the filter housing via a manually operated valve into a collection container with a coffee filter. The textile fibers then remain as retentate in the coffee filter like coffee grounds and can be disposed of professionally. The filtrate is discharged into the sewage system. The separated fibers, ie the retentate, are or will be disposed of with the second filter screen in the household waste.

US 2009/0071912 A1 also proposes a fluid filter for separating textile fibers from washing machine waste water. The fluid filter consists of a filter drum with a coaxial inlet rotating around a helix. The helix directs the fluid flow against the single filter screen so that it is flushed free by the fluid flow. Due to the rotation of the filter screen relative to the helix, this acts like a screw conveyor and transports the separated textile fibers as retentate to the free end of the filter drum, which is opposite the inlet.

The subject of the utility model DE 202019003 578 U1 is a filter system for removing microfibers from the waste water of a washing machine with a vertically extending drain pipe. In the drain pipe are in the direction of flow several filter elements are arranged in a row one behind the other. In the side wall of the sewage pipe there are maintenance openings that allow access to the screens.

DESCRIPTION OF THE INVENTION The invention is based on the knowledge that the known technical teachings for separating microplastics from washing machine waste water only work theoretically, but are difficult in daily use and are therefore not accepted or only poorly accepted by the end users. For integration into a machine such. B. a washing machine, the proposals according to the prior art are not yet suitable.

The invention is based on the object of specifying a solution that enables simple handling when cleaning washing machine waste water or other fluids to be cleaned.

This object is achieved by the fluid filter according to claim 1, as well as by a washing machine with the fluid filter and also by a maintenance cover for the fluid filter or a washing machine with the fluid filter. In particular, the object is achieved by a combination of a filter screen and a brush according to claim 18. Preferred embodiments are the subject matter of the dependent claims. The fluid filter has a filter housing, at least one first filter screen and at least one second filter screen. The filter housing forms a cavity and has at least one inlet opening and at least one outlet opening through which a fluid can flow into the cavity and out again. Correspondingly, the arrangement of the inlet opening and outlet opening specifies a direction of flow. In other words, the inflow opening and outflow opening define a flow direction from the inflow opening to the outflow opening. The first filter screen is arranged in the cavity, with the inlet opening and the outlet opening being connected to one another in a communicating manner by the filter screen. In this context, communicatively connected means that a fluid stream can flow from the inlet opening through the first filter screen to the outlet opening, particles contained in the fluid being separated at the filter screen. The first filter screen at least partially delimits a first filter space. As usual, the first filter chamber is on the inlet side of the first filter screen, has a retentate outlet and is limited on the outlet side by the first filter screen. A second filter screen is preferably also arranged in the cavity of the filter housing, with the inlet and outlet also communicating with one another through the second filter screen. The second filter screen is therefore preferably connected at least partially in parallel with the first filter screen, the term parallel here referring to the flow of the fluid (eg the waste water). The retentate outlet of the first filter screen is preferably arranged on the inlet side of the second filter screen. Consequently, fluid from the first filter chamber can also enter the second filter chamber through the retentate outlet; additionally or alternatively, the second filter chamber can have a separate fluid inlet.

In terms of a flow diagram, the first filter screen and the second filter screen are therefore arranged in parallel (“connected”) for the fluid and arranged in series (“connected”) for the retentate. The series connection results because it is at least possible for retentate to enter the second filter chamber from the first filter chamber, if not even structurally provided for, and retentate exit from the second filter chamber is prevented by the second filter screen. Consequently, when the fluid filter is in operation, the retentate of the first filter screen is caught in the second filter screen. A manual cleaning of the first filter screen can be omitted. In addition, the first filter sieve can preferably be cleaned automatically, as a result of which the flow resistance through the fluid filter is limited at the top. This reliably counteracts clogging of the fluid filter. The preferred automatic cleaning can e.g. This can be done, for example, by a motor-driven brush whose bristles sweep over the first filter screen. This means that a free end of at least one bristle rests against the first filter screen, preferably on the inlet side, and/or the brush is driven to move relative to the first filter screen, with the movement of the free end of the bristle being described by a trajectory that lies at least partially on the first filter screen.

Preferably the fluid filter has an agitator. The agitator particularly preferably has at least one agitator shaft, which is preferably driven by a motor. For example, an electric motor and/or a hydraulic motor driven by the flow of the waste water (and/or the water inlet) can be used as the drive.

The bristles can be attached to the agitator. As a result, the free ends of the bristles can sweep over the side of the first filter screen facing the first filter space when the agitator moves. For this purpose, the agitator can have at least one web. The web or webs can be connected to the agitator shaft, for example. At least one bristle holder can be attached to at least one web. For example, in the case of a rotating agitator, the bristle holder can preferably be attached to a radial end of the at least one web, radial at this point referring to the axis of rotation of the agitator shaft. For example, the agitator can also be a bristle holder.

The bristles can be attached to the bristle holder on the side of the bristle holder facing the first filter screen. When the agitator shaft is driven by a drive, e.g. B. by an electric or hydraulic motor, is rotated, then the bristle holders are taken over the webs and the bristles sweep over the first filter space facing side of the first filter screen. In this way, retentate adhering to the filter screen is cleaned off. The retentate can include, for example, microplastic particles, fibers and the like.

The retentate can be transported on the one hand by the fluid flow from the inlet opening to the outlet opening and/or by the agitator. For example, the bristle holders can be arranged in a spiral or in the form of spiral segments, so that the agitator resembles a screw conveyor. Likewise, the webs or the at least one web or parts thereof can be designed as a helix or as helix segments. One could say that at least one web is preferably designed as a thread or thread segment and/or has at least one thread and/or at least one thread segment. Just as the number of bristle holders is not limited, i.e. "one bristle holder" is to be understood in the sense of "at least one bristle holder", the number of webs is not limited, i.e. preferably there is at least one web on which preferably at least one bristle holder is attached. Particularly in the case of rotating brushes, at least three bristle holders are preferred, as a result of which an additional radial bearing can be omitted.

The filter housing particularly preferably has a maintenance opening which is closed with a maintenance cover. As usual, the maintenance cover is preferably easy to detach, i.e. the maintenance opening can be released easily. Any blockages or other problems with the fluid filter can be easily rectified through the maintenance opening.

The second filter screen is particularly preferably attached to the maintenance cover. It is then sufficient to open the maintenance cover at regular intervals, with the second filter screen being removed from the housing. The contour of the second filter screen is preferably smaller than the contour of the maintenance cover when viewed from above the maintenance cover, so that the second filter screen can be removed easily. Other contours are also possible. at When choosing the contour, however, it should preferably be taken into account that the second filter screen can preferably be removed through the maintenance opening. For example, filter screens in the form of toroidal segments are also possible. When the maintenance cover is open, the second filter screen can then be cleaned and used again or, if necessary, replaced together with the maintenance cover and/or removed with the maintenance cover, cleaned and used again. However, the second filter screen is preferably only used once, because otherwise there is a risk that a user will wash out the screen, as a result of which the retentate separated from the wash water will then end up in the waste water system. In order to prevent a second filter screen that has been washed out from being reused, a machine-readable identification marking can be arranged on it, e.g. B. an RFID chip. A machine control can then use the identification mark to recognize whether a previously removed second filter screen was reinserted or whether a different (new) second filter screen was used. If a previously removed second filter screen is reinserted, the machine control can prevent operation of the machine and/or display a warning message

The need to replace or clean the second filter screen can e.g. B. be symbolized by a display of a washing machine control. In the simplest variant, the second filter screen is changed or cleaned after a specified number of washing cycles. Alternatively or additionally, the volume of the retentate held back in the second filter screen can be measured and, if the measured value reaches a predetermined target value, the need to replace and/or clean the filter screen can be symbolized. As an alternative or in addition, a wash program can also be ended automatically from the limit value and/or a limit value above it and/or the restart of a new wash program can be prevented by the controller. As already explained above, it is particularly preferred if at least part of the second filter screen at least partially delimits at least one second filter chamber. The second filter chamber has an inlet opening which is in communication with the retentate outlet of the first filter chamber, so that both retentate from the first filter chamber and unfiltered fluid can enter the second filter chamber. When passing through the second filter screen, the fluid becomes the filtrate and the retentate is held back in the second filter chamber. In this sense, the second filter chamber is preferably at least retentate-tight (possibly also fluid-tight) connected to the first filter chamber, with the connection preferably being detachable. For example, a sealing ring can be arranged between a surface delimiting the retentate outlet and a surface delimiting the inlet opening, with the free space, ie the transition between the retentate outlet and inlet opening being permeable for retentate from the first filter chamber and the fluid to be filtered.

As usual, the term filter room designates an area separated from the clean side of the cavity by the corresponding filter screen. Such filter rooms can e.g. B. circular-cylindrical, hemispherical, polygonal, conical, wavy or the like. Not all boundary surfaces of the first or second filter space are necessarily formed by the first or second filter screen. For example, part of the housing wall can delimit part of the first and/or filter chamber.

The fluid filter particularly preferably has a closure for the inlet opening of the second filter chamber, the closure being movable between an open position and a closed position. In the closed position, the closure closes the inlet opening and thus the second filter space at least retentate-tight, preferably even fluid-tight. In the open position, the inlet opening is, as the name suggests, open, i.e. a flow of retentate and fluid from the first filter chamber into the second filter chamber can take place, preferably unhindered. As is generally customary, in this case displaceable means any type of movement, ie rotation, translation or superpositions of rotation and translation. One could also use the term movable instead of movable. Once the closure has been moved to the closed position, the second filter screen can be removed from the housing without the risk of the retentate or part of it falling out of the second filter chamber. The handling is clearly simplified, the functional reliability is increased. The closure can be viewed as a switching valve that closes or opens the inlet of the second filter chamber, the switching valve being in the open position during operation of the fluid filter, preferably being in the open position permanently. The switching valve is then closed before, during or as a result of the removal of the second filter screen, ie when the second filter screen is removed and/or when the maintenance cover is open, the closure is in the closed position.

The closure is particularly preferably prestressed in the direction of its closed position, at least when it is not in the closed position. This means that the closure, provided no external forces act on it, automatically returns to its closed position. This can be achieved, for example, in that when the closure is opened, a spring is tensioned, which loads the closure into its closed position. Instead of the elastic spring, another energy store, preferably a potential energy store, can also be used. The fluid filter preferably has an opening element which, when the maintenance flap is closed, keeps the closure in its open position or, when the maintenance flap is closed, moves the closure from the closed position into the open position. When the maintenance flap is subsequently opened, the opening member can preferably release the path of the closure into its closed position, so that the inlet opening of the second filter chamber is reliably and automatically closed as soon as the maintenance flap is opened. Handling when changing the second filter screen is consequently further simplified.

The fluid filter can also preferably have at least one movable compression means that can be moved from a neutral position into a compression position. In the compression position, the compression means can deform the second filter screen and thereby compress the second filter chamber. The retentate is consequently compressed and any fluid still present is pressed out of the second filter space through the second filter screen. When removing the second filter screen, the risk of dripping is therefore significantly reduced if the movable compression means has been moved into the compression position at least once beforehand. If necessary, it can of course also be brought back into the neutral position before removal. Alternatively or additionally, in the compression position, the compression means can separate at least one section of the second filter space from at least one other section of the second filter space. This effectively reduces the second filter chamber, which also leads to compression of the retentate, i.e. any fluid stored in the retentate is pressed through the second filter screen and the risk of dripping when the second filter screen is removed is further reduced. For example, a slide can be moved through an inlet opening of the second filter screen along the filter screen into the second filter chamber, as a result of which retentate arranged in front of the slide in the direction of movement is compressed and consequently dewatered. The slide is preferably moved in the direction of a section of the second filter screen, as a result of which the retentate is compressed between the second filter screen and the corresponding section.

The maintenance cover particularly preferably has a lock that has a locked position and an unlocked position. In the locked position the lock prevents or at least inhibits opening of the maintenance cover, e.g. B. in that the locking mechanism or a part of it engages in a form-fitting manner in a recess in the maintenance cover and/or the housing. Alternatively, the locking can also or additionally have a non-positive effect on the maintenance cover, so that if the locking mechanism malfunctions, the maintenance cover can be opened, e.g. B. can be opened non-destructively by applying a lever. The lock is preferably in operative connection with the closure for the inlet opening and/or the compression means. Moving the closure into the closed position preferably causes the locking mechanism to be unlocked and vice versa. In addition or as an alternative, moving the compression means into the compression position and optionally back into the neutral position can unlock the lock. The lock is preferably self-locking when the maintenance cover is closed. The locking can ensure that the maintenance cover is only opened when the inlet opening is closed and/or after superfluous fluid has been pressed through the second filter screen. The danger of dripping when removing the second filter screen is further reduced.

An agitator is particularly preferred at least in the first filter chamber. The agitator can be powered electrically and/or by the flow of fluid. For example, the agitator can have at least one brush whose bristles brush over the first filter screen or at least parts of it, ie brush it off. As usual, the brush can have a bristle holder to which the bristles are attached. The bristles, more precisely by sweeping the bristles over the first filter screen, can prevent clogging of the first filter screen and at the same time a reliable removal of the retentate through the retentate outlet into the second filter chamber can be promoted. As a result, a uniform flow resistance of the fluid filter can be ensured. Preferably, the bristles sweep over at least a portion during operation of the second filter screen, so that the retentate can accumulate there like a filter cake.

The bristles preferably have a fiber diameter d<d _max , where d _max is an element from the set {0.14 mm; 0.12mm; 0.1mm; 0.09mm; 0.08mm; 0.05 mm}, ie ∈ {0.14; 0.12; 0.1; 0.09; 0.08; 0.05}. In these cases, the cleaning particularly effective. Tests have shown that the lower limit d _min for the fiber diameter of the bristles is 5 μm, ie d _min >5 μm. In summary, it would then preferably be d _min ≤ d ≤ d _max , where G

{0.14; 0.12; 0.1; 0.09; 0.08; 0.05} and d _min ≥ 5 µm. Plastic fibers with a corresponding fiber diameter can reliably clean microplastics from the first sieve, with the fiber length preferably being between 14 and 2 mm. Particularly preferably between 10 and 4 mm. The first filter screen and the second filter screen preferably each have a mesh size m ₁ , m ₂ . The lower limits of the two mesh sizes m ₁ , m ₂ is preferably an element from the set U = {20 μm, 30 μm, 40 μm, 45 μm, 50 μm} and the upper limit from the set 0 = {50 μm, 55 μm, 60 μm, 70 μm , 80μm, 90μm, lOOμm }, so that for the mesh width m _i applies u < m _i < o,u ∈ U, o ∈ 0, i ∈ {1,2}. For example, mesh sizes between 20 μm and 80 μm are preferred. Mesh sizes between 30 μm and 70 μm are particularly preferred, and mesh sizes between 45 and 60 μm are very particularly preferred.

In addition, extensive tests have shown that the optimal fiber diameter correlates with the free length of the bristles. The ratio d/l of the fiber diameter d of the bristles to the free fiber length l of the bristles is preferably about 20 to 200, better in the range from 50 to 100. That means that preferably applies A combination of a filter screen and a brush with one of the properties mentioned can also be used in other filter applications, in particular without the second filter screen described above. Such a combination is described in claim 20. Of course, it can be assumed that a free end of at least one bristle is in contact with the first filter screen, preferably on the inlet side, and/or the brush is driven so that it can move relative to the first filter screen, with the movement of the free end of the bristle being described by a trajectory that is at least Part lies on the first filter screen. The fluid filter described above can be very easily z. B. in a washing machine or also in any other machine with a machine housing, in particular if the machine has a fluid basin with a pump sump. A fluid drain connection, e.g. B. a water drain connection, z. B. for washing water. The inlet opening of the fluid filter is preferably connected to the pump sump in a fluid-tight manner. The outlet opening of the fluid filter is preferably connected in a fluid-tight manner to the suction side of the fluid pump. On the pressure side, the pump is preferably connected via a waste water line with a drain connection, e.g. B. connected to a washing water drain connection. Alternatively, the pump can also be arranged between the pump sump and the inlet opening and correspondingly connected to the pump sump and the inlet opening of the fluid filter.

The drain port is typically located above the pump sump and its height defines the maximum fill height of the machine. When arranging the fluid filter between the pump sump and the suction side of the pump, a reservoir is particularly preferred between the fluid filter and the suction side of the pump, the volume of which corresponds at least to the volume of the waste water line. This can prevent filtrate from flowing back into the fluid filter or the pump sump when the pump is switched off flows. When the maintenance flap is opened, no fluid escapes from the machine. The same effect can be achieved if at least one check valve is arranged on the outlet side of the first filter screen and/or the second filter screen, which only allows a flow from the clean side of the at least two filter screens to the suction side of the pump. Once the filtrate has been sucked out of the fluid filter housing, it cannot flow back into the cavity formed by the filter housing.

Alternatively or additionally, a non-return valve can be arranged on the inlet side of the first filter space and/or first filter screen, e.g. B. in the inlet opening or on the inlet side of the inlet opening. If a non-return valve is arranged on the inlet side of the first filter screen, it is preferred if at least one optional bristle sweeps over the valve seat and/or the valve tappet when the non-return valve is open, in order to avoid an accumulation of fibers on the sealing surfaces of the non-return valve. Like the optional bristles already mentioned above, these bristles can be arranged on the optional agitator, possibly on an optional bristle holder.

Description of the drawings

The invention is described below by way of example, without restricting the general inventive idea, using exemplary embodiments with reference to the drawings.

FIG. 1 shows a first example of the fluid filter.

Figure 2 shows a second example of the fluid filter.

Figure 3 shows a third example of the fluid filter.

Figure 4 shows a fourth example of the fluid filter.

Figure 5 shows a maintenance cover for the fluid filter. Figure 6 shows a fourth example of the fluid filter.

FIG. 7 shows a maintenance flap with a filter screen.

FIG. 1 shows a fluid filter 1 with a housing 10. The housing 10 has a maintenance opening which is closed by a maintenance cover 11 in FIG. The closure is preferably fluid tight. This can e.g. This can be done, for example, by a seal clamped between the maintenance cover 11 and an edge of the housing 10 delimiting the maintenance opening, a labyrinth seal or the like. In FIG. 1, the maintenance cover is attached to the edge of the housing and fixed by a friction fit. Alternatively, however, other connection techniques can also be used, such as a threaded connection, a bayonet lock, a snap-in lock, a swivel connection, . . . ie all of these examples can be replaced by any other, preferably detachable, fastening technique. The housing 10 has an inlet opening 16 and an outlet opening 17. The inlet opening 16 can e.g. B. via a line z. B. connected to a pump sump or the pressure side of a pump of a washing machine or other machine. The drain opening 17 can, for. B. be connected to the suction side of a pump for pumping a fluid. Both the inlet opening 16 and the outlet opening 17 allow access to a cavity 15 enclosed by the filter housing 10. A first filter screen 21 and a second filter screen 22 are preferably arranged in the cavity 15 of the filter housing. The first filter screen 21 delimits a first filter space 25 which communicates with the inlet opening 16 . In the example shown, the first filter screen 21 is barrel-shaped and the first filter space 25 is correspondingly at least approximately a circular cylinder with a longitudinal axis 2. However, other geometries of the first filter space are also possible. Just to keep the figure clearer, only the cut surface of the filter screens 21, 22 is shown (applies to all figures), the interior view of the two filter screens, which is actually to be shown in the sectional drawings, was omitted because the other details could hardly be recognized against the grid background.

On the side facing away from the inlet opening 16, the first filter chamber 25 has a retentate outlet. In the example shown, the retentate outlet is the passage opening of a sealing ring 23, which at the same time forms the inlet opening of a second filter chamber 26. The second filter space 26 is defined by the second filter screen 22 in a manner similar to the first filter space 25 defined by the first filter screen 21 . The first filter screen 21 and the second filter screen 22 are connected by a seal 23 to form a filter element 20 . A wall, e.g. B. that of the housing cover 11, preferably delimits the second filter chamber 26 on the side opposite the inlet opening 23. Alternatively, the second filter chamber 26 can also be delimited by a separate base and/or the second filter screen 22 instead of by the wall. The second filter screen can e.g. B. form a filter basket.

The fluid filter 1 preferably has an agitator 30. The agitator 30 particularly preferably has an agitator shaft 31 to which bristles 34 are attached, the free ends of which touch the side of the first filter screen facing the first filter space 25 when the agitator 30 moves 21 cross over. For this purpose, the agitator z. B. webs 32, at the radial end of which at least one bristle holder 33 is attached. The bristles 34 are attached to the bristle holder 33 on the side of the bristle holder 33 facing the first filter screen 21 . If the shaft 31 is set in rotation by a drive 80, the bristle holders 33 are taken along via the webs 32, so that the bristles 34 sweep over the side of the first filter screen 21 facing the first filter chamber and thereby remove residue adhering to the filter screen 21, e.g. g. microplastic particles. As in the example shown, the bristles 34 do not sweep over the second filter screen 22 or at least not completely. thereby accumulated during operation of the fluid filter 1 in the second filter chamber retentate on the side of the second filter screen 22 facing the second filter chamber 26.

The retentate can be transported on the one hand by the fluid flow from the inlet opening 16 to the outlet opening 17 and/or by the agitator BO. For example, the bristle holders 33 can be arranged spirally or in the form of spiral segments, so that the agitator resembles a screw conveyor. At this point it should be noted that the drawing shows two bristle holders 33, but that this number is merely an example and is to be understood in the sense of "at least one bristle holder". In operation, a fluid to be filtered, e.g. B. a washing water to be filtered from a washing machine or another machine is fed via the inlet opening 16 into the first filter chamber 25 and through the retentate outlet opening also into the second filter chamber 26 . A part of the fluid flows through the first filter screen 21 and the second filter screen 22 and is drawn off at the outlet opening 17 . Contaminants carried along by the fluid remain attached both to the first filter screen 21 and to the second filter screen 22 . The impurities separated on the first filter screen 21 are cleaned off by the bristles 34 of the agitator 30, so that the first filter screen 21 is kept free. Retentate cleaned from the bristles 34 passes through the flow and preferably through the agitator 30 into the second filter chamber 26, where it is separated again, but this time on the second filter screen 22. The cleaned fluid, ie the filtrate, can leave the fluid filter 1 through the outlet opening 17 . Preferably, before the second filter chamber 26 is completely filled with retentate, the fluid flow through the inlet is stopped, preferably at least for a short time, with any remaining fluid residues preferably being drawn off through the outlet opening 17 . Now the maintenance cover 11 can be opened and the retentate can be removed from the second filter chamber. In a preferred In this embodiment, as shown, the second filter screen is firmly connected to the maintenance cover 11, so that when the maintenance cover is opened in the second filter chamber 26, accumulated retentate can be removed together with the second filter screen. This unit can then be disposed of in accordance with local regulations and replaced with a new service cover 11 with a filter screen 22 attached.

FIG. 2 shows a further fluid filter 1, which is largely the same as the fluid filter 1 according to FIG. 1, so that the description of FIG. 1 can be read in full on FIG. In addition, the fluid filter 1 in FIG. 2 has a compression means 40 with which the retentate collected in the second filter chamber 26 can be compressed. As a result, on the one hand the maintenance intervals of the fluid filter can be extended and on the other hand the retentate in the second filter chamber 26 can be compressed with the compression means 40 so that fluid still contained therein drains through the filter element 20, causing undesired dripping of fluid from the maintenance cover 11 or from the second filter chamber 26 can be prevented or at least reduced. The compression means 40 preferably has a grid 41 which, as indicated by the double arrow, can be moved parallel to the wall of the second filter screen. In the example shown, the grid sits on the free end of a piston rod of the agitator 30. It should also be mentioned that the mesh size of the grid 41 is larger than the mesh size of the filter element 20, so that the cleaned retentate can pass through the meshes of the grid 41 can be transferred to the second filter chamber 26 .

FIG. 3 shows a further fluid filter 1 and the description of FIG. 1 can again be (almost) completely applied to the fluid filter 1 in FIG. Only the differences are explained to avoid repetition. The fluid filter in FIG. 3 differs from the fluid filter in FIG. 1 only in that that the first filter chamber and the second filter chamber are not arranged coaxially but at an angle to one another. As a result, the retentate collects at the bottom of the second filter chamber 26, at least also due to the force of gravity.

FIG. 4 shows another fluid filter in a longitudinal section along the longitudinal axis 2. The description of FIG. 1 can also (almost) completely refer to FIG. 4, so that in the following only differences between the two fluid filters 1 are discussed in FIG the first filter screen 21 on the side facing away from the inlet opening 16 in a section 27 referred to as a taper 27 to form a connecting piece 28 whose open end forms the retentate outlet 29 . The connecting piece 28 with the retentate outlet protrudes into the second filter chamber 26 through a seal 23 that rests at least largely sealingly on the outside of the connecting piece 28 . The seal 23 delimits the second filter chamber 26 on the inlet side. The seal 23 can (other than shown) z. B. on the second filter screen 22 may be attached. In the example shown, the seal 23 is attached to the service cover 11 . For example, the seal 23 may be a sealing membrane attached to an inlet-side portion of an optional annular land 42 . Inlet side refers here to the inlet of the second filter chamber 26, the inlet being the opening of the second filter chamber 26 facing the inlet 16 of the housing 10 (in relation to the direction of flow). In the example shown, the seal 23 spans the second filter chamber on the inlet side. At least the optional section of the seal 23 between the second filter screen 22 and the optional annular web 42 of the maintenance cover 11 can be designed as a rigid wall. At least the section of the seal 23 through which the connecting piece 28 protrudes or into which it engages is preferably made of an elastic material, e.g. B. from a rubber-elastic material.

The optional ring ridge 42 can, for. B. as shown in Figure 4 together with the bottom of the maintenance cover 11, the second filter screen and the second filter chamber 26 enclose. In order to improve the flow of the filtrate Ring web 42 preferably has at least one drip opening 47 in its area facing the inlet.

If the maintenance cover in FIG. 4 is removed, the base of the maintenance cover 11 with its annular web 42 forms a basin which prevents residual fluid from dripping off undesirably from the second filter chamber. Any filtrate escaping from optional drip openings 47 can e.g. B. be retained by an optional edge web 117 (see FIG. 5) z. B. may have a thread or a joint 48 (cf., for example, FIG. 7) for connecting the maintenance cover 11 to the base body of the housing 10 . Optional elastic flaps 231 on the seal 23 can, as outlined in FIGS. 5 to 7, at least largely close the inlet to the second filter chamber, ie they form a closure 231 of the inlet, which greatly simplifies a clean replacement of the second filter screen . When inserting the second filter screen 22 into the housing, the connecting piece 28 acts as an opening member 28 for closing the inlet of the second filter chamber 22. In addition, the optional flaps 231 can prevent improper emptying of the filter, e.g. by washing out. The tabs 231 serve here as an example of a closure of the inlet opening that is preferably biased into its closed position, similar to a duckbill valve (EN: "Duckbill valve"). Alternatively, the closure can be designed as a duckbill valve. As a further alternative, the closure can at least e.g. have an articulated closure flap or the like, which can preferably be moved into the second filter chamber. In the open position, the closure flap is particularly preferably pretensioned in the direction of its closed position. As shown in FIG be connected to the maintenance cover 11, so that correspondingly less waste is produced can be used in the maintenance cover 13. A snap-in connection between the base 13 and the maintenance cover 11 is preferred, but other fastenings are also possible, such as a bayonet, screw thread, etc. p. The optional floor 13 can also be part of the second filter screen 22 . The optional floor 13 can also be provided in the embodiments of FIGS. Incidentally, the description of FIGS. 4 and 5 can also be applied to FIG.

FIG. 7 is largely identical to FIG. 6 and differs only in that the maintenance cover is not attached to the base body with a screw connection but with a joint 48. Otherwise, the description of FIG. 6 can also be read with reference to FIG will.

Reference List

1 fluid filter

2 longitudinal axis

10 housing

11 Housing cover / maintenance flap / maintenance cover

117 edge bar

12 case bridge

13 floor

15 cavity

16 inlet opening

17 drain hole

20 filter insert

21 first filter screen

22 second filter screen

23 seal

231 closure / elastic flaps

25 first filter room

26 second filter room

27 taper

28 nozzles / opening organ

29 retentate outlet

30 agitators

31 wave

32 bars

33 bristle holders

34 bristles Compression means Grid Ring bar Drip hole joint

drive / engine

Claims

patent claims

1. Fluid filter (1) with a filter housing (10), a first filter screen (21), a second filter screen (22), an inlet opening (16) and an outflow opening (17), wherein the filter housing (10) has a cavity (15) and has at least the inlet opening (16) and the outlet opening, the first filter screen (21) is arranged in the cavity (15), the first filter screen (21) at least partially delimits a first filter space (25) which Inlet (16) and outlet (17) communicate with each other through the first filter screen (21), the first filter chamber (25) has a retentate outlet, characterized in that the second filter screen (22) is in the cavity (15) of the filter housing (10), the inlet (16) and outlet (17) communicate with one another through the second filter screen and the retentate outlet is arranged on the inlet side of the second filter screen (22).

2. Fluid filter (1) according to claim 1, characterized in that the filter housing (10) has a maintenance opening, that the maintenance opening is closed with a maintenance cover (11), and that the second filter screen (22) on the maintenance cover (11 ) is attached.

3. Fluid filter according to one of the preceding claims, characterized in that the first filter screen (21) and the second filter screen (22) are arranged in parallel relative to the fluid flow direction.

4. Fluid filter according to one of the preceding claims, characterized in that the first filter chamber (21) and the second filter chamber (22) are arranged in relation to the retentate flow in series.

5. Fluid filter (1) according to one of the preceding claims, characterized in that at least part of the second filter screen (21) at least partially delimits at least one second filter space (26), the second filter space (28) having an inlet opening , which is attached to the retentate outlet, thereby forming a retentate passage from the first filter space into the second filter space.

6. Fluid filter (1) according to claim 5, characterized in that the fluid filter (2) has a closure (231) for the inlet opening, the closure (231) being movable between an open position and a closed position, the In the closed position, the closure (231) closes at least one section of the second filter chamber (25) in an at least retentate-tight manner.

7. Fluid filter (1) according to claim 6, characterized in that the closure (231) is biased into its closed position, with the maintenance flap (11) closed the closure (231) of an opening member (28) of the fluid filter (1) into an open position is positioned, when the maintenance flap (11) is opened, the opening element (28) releases the path of the closure (231) into its closed position.

8. Fluid filter (1) according to any one of the preceding claims, characterized in that the fluid filter has at least one movable compression means (40) which can be moved from a neutral position to a compression position can be moved, with the compression means (40) deforming the second filter screen (22) in the compression position and thereby compressing the second filter space (25) and/or at least one section of the second filter space (25) from at least one other section of the second filter space (25) separates.

9. Fluid filter (1) according to claim 6 or 8, characterized in that the maintenance cover (11) has a lock which at least inhibits opening of the maintenance cover (11) and that the lock is in operative connection with the closure ( 231) for the inlet opening and/or the compression means (40), and moving the closure (231) into the closed position and/or moving the compression means (40) into the compression position releases the locking.

10. Fluid filter (1) according to one of the preceding claims, characterized in that an agitator (30) is movably mounted relative to the first filter screen (21).

11. Fluid filter (1) according to claim 10, characterized in that bristles (34) pointing in the direction of the first filter screen (21) are fastened to the agitator (30) and rest at least partially on the first filter screen (21). - genes and their movement paths are defined by trajectories.

12. Fluid filter (1) according to claim 11, characterized in that at least part of the inlet-side surface of the second filter screen (22) is arranged outside the trajectories of the bristles (34).

13. Fluid filter (1) according to claim 11 or 12, characterized in that the bristles (34) are made of plastic and have a fiber diameter d less than or equal to d _max , ie d ≤ d _max , where ∈ {0.14; 0.12; 0.1; 0.09; 0.08; 0.05} and where d > 5 mpi.

14. Fluid filter according to one of the preceding claims, characterized in that the first filter screen and/or the second filter screen have at least one mesh with a mesh size m ₁ or m ₂ where u ≤ m _i ≤ o and u ∈ U = { 20μm 30μm 40μm 45μm 50μm} and o ∈ O =

{50μm 55μm 60μm 70μm 80μm 90μm 100μm} and i ∈ {1, 2}.

15. Washing machine with a washing machine housing with at least one wash water drain connection, at least one fluid basin with a pump sump and at least one pump, characterized in that the washing machine has a fluid filter (1) according to at least one of the preceding claims.

16. Washing machine according to the preceding claim, characterized in that the inlet opening (16) is fluid-tightly connected to the pump sump, and/or the outlet opening (17) is fluid-tightly connected to the suction side of the pump, and/or the pump is connected to it on the pressure side is connected in a fluid-tight manner to a waste water pipe, and/or the waste water pipe has an end remote from the pump, this end remote from this forming the washing water outlet connection, and/or the washing water drain connection is located above the pump sump.

17. Washing machine according to the preceding claim, characterized in that between the fluid filter (1) and the suction side of the pump there is a reservoir, the volume of which corresponds at least to the volume of the waste water pipe, and/or on the outlet side of the first filter screen (21) and/or or the second filter screen (22) is at least one non-return valve that only allows flow from the clean side of the at least two filter screens (21, 22) to the suction side of the pump.

18. Maintenance cover (11) for a fluid filter according to one of Claims 2 to 14, characterized in that the maintenance cover (11) has a filter screen (22), at least one section of the filter screen (22) having at least one section of a filter chamber (25). an inlet opening, at least one fluid-tight wall (42, 117) surrounds the filter screen at a distance, the inlet opening of the filter screen (22) remaining free, a closure (231) of the inlet opening can be moved between a closed position and an open position, wherein the closure in the closed position closes at least the inlet opening at least retentate-tight.

19. Maintenance cover (11) according to the preceding claim, characterized in that there is a gap between at least one section of the wall (42) and at least one section of the filter screen (22), and that the wall has an outlet opening (47), in the wall (42) is an outlet valve having a valve means that is movable between an open position and a closed position, the valve means is biased towards the closed position, the valve means has or is connected to an abutment with a force on the Abutment moves the valve means from the closed position to the open position.

20. Combination of a first filter screen (11) in particular for a fluid filter according to one of claims 1 to 14 and at least one brush with bristles (34) for cleaning the first filter screen, characterized in that the bristles (34) are made of plastic and have a fiber diameter d less than or equal to d _max , ie d ≤ d _max , where {0.14; 0.12; 0.1; 0.09; 0.08; 0.05} and where d ≥ 5 mpi and/or the first filter screen (11) has at least one filter mesh with a mesh width m ₁ where u ≤ m ₁ ≤ o,u ∈ ∈ , o E 0 and U = {20 μm , 30μm 40μm 45μm, 50μm} and 0 =

{50μm 55μm 60μm 70μm 80μm 90μm 100μm } and/or the ratio d/l of the fiber diameter d of the bristles to the free fiber length l of the bristles is approximately

21. Combination according to claim 20, characterized in that the combination is part of a fluid filter according to one of claims 1 to 12 and/or part of a washing machine according to one of claims 13 to 15 and/or part of a fluid filter with the maintenance cover one of claims 16 and 17.