CN117018865A

CN117018865A - Filter system, water-conducting household appliance and method for filtering a fluid

Info

Publication number: CN117018865A
Application number: CN202310519170.XA
Authority: CN
Inventors: A·比朔夫; H·埃格迈尔
Original assignee: BSH Hausgeraete GmbH
Current assignee: BSH Hausgeraete GmbH
Priority date: 2022-05-09
Filing date: 2023-05-09
Publication date: 2023-11-10
Also published as: DE102022204527A1

Abstract

The invention provides a filter system (1) for filtering particles (7) from a fluid for a water-conducting household appliance. The filtration system (1) comprises: -a filter membrane (2), the filter membrane (2) being configured for filtering particles (7) from a fluid; -first holding means (3), said first holding means (3) holding said filter membrane (2) on a first side of said filter membrane (2); -second holding means (4), which second holding means (4) hold the filter membrane (2) on a side of the filter membrane (2) opposite to the first side of the filter membrane (2); and a tensioning element (5), the tensioning element (5) being configured for exerting a pretension on the first holding device (3) and/or the second holding device (4) in order to tension the filter membrane (2). A water-conducting household appliance and a method for filtering a fluid are also provided.

Description

Filter system, water-conducting household appliance and method for filtering a fluid

Technical Field

The present invention relates to a filter system for a water-conducting household appliance, a water-conducting household appliance and a method for filtering a fluid.

Background

Filters are often provided in the drain or circulation lines of water-conducting household appliances to clean particles in the fluid. Particularly in filters with dense mesh filtration membranes, it is common for the filter to become clogged quickly. Here, the filter membrane (filtermembrane) is generally extensible due to its material and/or configuration. Thus, the filtering membrane (particularly in a state of being mixed into particles) may be stretched (or deformed) due to the water pressure of the fluid. Such stretching may result in a large amount of space being necessary downstream of the filter membrane to accommodate the stretched filter membrane. It is necessary to provide sufficient installation space downstream of the filter. As a result, the filter system must be designed large enough to provide this space.

Disclosure of Invention

The object of the present invention is therefore to provide a device and a method for filtering a fluid, wherein the filter can be constructed particularly compactly.

This object is achieved by a filter system having the features of claim 1, a water-conducting household appliance having the features of claim 9 and a method for cleaning a fluid having the features of claim 10.

According to an aspect of the present invention there is provided a filtration system for a water-conducting domestic appliance for filtering particles from a fluid, wherein the filtration system comprises: a filter membrane configured to filter particles from a fluid; a first holding means holding the filter membrane on a first side of the filter membrane; a second holding device that holds the filter membrane on a side of the filter membrane opposite to the first side of the filter membrane; and a tensioning element configured to exert a pretension on the first holding device and/or the second holding device, thereby tensioning the filter membrane.

An advantage of the present invention compared to the known prior art is that the filter membrane is tensioned independently of its own elasticity. This prevents the filter membrane from being stretched very far in the downstream direction (ausdehnt) even when other substances are mixed in. The filter system can thus be constructed in a particularly compact manner. In other words, by providing the tensioning element, an extension curve describing the elastic extension (Dehnung) of the filter membrane may be defined by the tensioning element. In contrast, in the prior art the expansion curve can only be influenced by working the filter membrane, whereas in the present filter system the expansion curve can be defined by the tensioning element. It is thereby ensured that the filter membrane can be stretched in correspondence with the available space on the downstream side of the filter membrane.

The water-conducting household appliance may be a washing machine, a washer-dryer or a dishwasher. However, other water-conducting household appliances are conceivable in which a filter system for filtering particles is provided. The fluid may be a liquid or a mixture of liquids. The fluid may also include treatment agent residues, calcium, particulates, and the like. In addition, the fluid may also be a liquid-gas mixture. The particles may be residues of particles/articles to be treated (e.g. tableware, clothing, etc.). In addition, the particles may also include calcium residues or treatment agent residues. The particles may in particular also have microplastic. The filtration system may have a fluid supply and a fluid discharge. Thus, the fluid can flow from the fluid supply portion on the upstream side of the filter system to the fluid discharge portion on the downstream side of the filter system in the main flow direction, and the fluid flows through the filter system. In the path through the filtration system, the fluid may pass through a filtration membrane disposed between the upstream side and the downstream side of the filtration system.

The filter membrane may be a gauze membrane. In other words, the filter membrane may be a flat, flexible fabric (e.g., made of synthetic fibers or metal wires). The filter membrane may have a pore size of 25 μm to 150 μm, preferably 35 μm to 75 μm, particularly preferably about 50 μm. The first pore range provides advantages in manufacturing the filter membrane, as large tolerances are possible. This is therefore a particularly inexpensive possibility to provide a filter membrane. The second pore range provides a good optimization between efficient manufacturing of the filter membrane and the filtering performance, since minimal fluff can also be filtered for such pore range. The pore range of about 50 μm has proved to be particularly advantageous in filtering microplastic materials, while the filtration properties are good. As the geometry of the filter membrane, all shapes can be considered which can be formed from flat, soft fabrics and which do not deform significantly inside the filter membrane (e.g. the fabric side). In addition, shapes of formed bodies, such as catenary curves (katenoides), having a deployable surface or receiving a small amount of deformation within the self-elasticity of the filter membrane to approximate the deployable surface are also contemplated.

The first and second holding means may be means configured to hold the filter membrane. In particular, the holding means may be clamping means which hold the filter membrane on at least two opposite sides of the filter membrane. Preferably, these retaining means are part of the housing of the filtration system.

The tensioning element may be configured to exert a force directly on the first and second holding means themselves, or may be a device that exerts a force indirectly on the holding means. For example, the tensioning element can have, for example, a magnetic element which causes a pretension on the filter membrane by means of magnetic attraction and/or magnetic repulsion. In this way a tensioning element with very little wear can be provided. The direct force can be achieved, for example, by a spring structure. The spring structure may be a metal technical member capable of elastic deformation in use. For example, the tensioning element may be, for example, a spiral spring or a coil spring arranged between the first holding means and the second holding means. The helical spring may be, for example, a wire wound in a helical shape. Preferably, the diameter of the spring structure decreases from one end of the spring structure to the other end of the spring structure. A particularly advantageous spring characteristic can be achieved in this way, so that the filter membrane is always sufficiently tensioned. The indirect application of force on the holding means may be provided, for example, by: the tensioning element converts the pressure (e.g., fluid pressure) present in the filter system into a force acting on the first and second holding means. The tensioning element can thus be, for example, a device which supports the first and second holding devices in a floating manner and which transmits the pressure in the filter system (in particular the fluid pressure) to the holding devices in such a way that the holding devices can tension the filter membrane.

In other words, a particularly compact filter system can be provided by the filter system according to the invention, since the expansion of the filter membrane can be actively achieved by the first and the second holding device together with the tensioning element.

The filtration system preferably includes a wiper (Rakel) configured to move relative to the filtration membrane to scrape particles blocked by the filtration membrane. Filters in the drain or circulation lines of water-conducting household appliances are often blocked very quickly by the particles to be filtered. Mechanical cleaning of the filter membrane surface, so-called wiping, has proven to be an effective measure. The filtered particles on the surface can be scraped off periodically, continuously and/or as required by means of a preferably automatically operated mechanical scraper (i.e. by means of a wiper). In order for such a system to work reliably, the connection of the wiper to the filter membrane must be achieved with a certain pressing force. The filter membrane itself is elastic at least in the areas not supported by the possible support structure and is forced by pressure against the wiper. The wiper may be pressed into the filter membrane over a length, so that the filter membrane can be elastically pressed against the wiper. As mentioned above, the fluid pressure (back pressure) acting from the upstream side of the filter membrane in a water-conducting household appliance can typically contribute up to 1 meter of water column on the filter membrane, so that this fluid pressure presses the filter membrane away from the wiper edge and thereby reduces the contact force between wiper and filter membrane. In particular, contact between the wiper and the filter membrane may be completely lost, which may result in lifting of the filter membrane from the wiper. This effect may be progressive, i.e. the less wiping, the faster the pressure in the filtration system rises due to clogging of the filter membrane and the faster the subsequent clogging process will take place due to reduced pressing between the wiper and the filter membrane. This tendency can be inhibited and ensured by the connection of the holding devices and the tensioning element between the wiper and the filter membrane. The filter system according to the invention is thus particularly advantageous when joining wipes and provides a durable and tolerance-compensating system for uniformly tensioning the filter membrane, in particular on the wipes.

The wiper may be configured to clean the filtered particles of the filter membrane. For this purpose, the wiper may have suitably shaped edges. The edge of the wiper can be pressed against (or pressed against) the filter membrane by such a force: the force has a force component that is substantially conventionally directed towards the filter membrane. The wiper may also be movable on the surface of the filter membrane, wherein such movement may substantially follow the membrane surface. The wiper is rotatably disposed in the filter system. A particularly simple drive mechanism for the wiper can thereby be provided. Alternatively, the wiper may also be operated intermittently, so that the wiper can move in a reciprocating motion in the filtration system. In this case, a particularly stable filter system can be provided, since there is no need to provide space for the revolving wiper in the filter system.

The filter system preferably comprises a substantially cylindrical housing, wherein the filter membrane is preferably arranged at least in sections on the circumference of the housingIn this case, the first holding device is preferably arranged on the upper side of the housing, and the second holding device is preferably arranged in the lower side of the housing. In other words, the filter system may have a cylindrical shape on the peripheral side of which the filter membrane is at least partially arranged. In other words, the fluid to be filtered may be supplied axially to the interior of the cylindrical housing and discharged from the housing radially outwards via the peripheral surface through the filter membrane. The filter membrane can also be arranged in sections on the circumferential surface of the cylindrical housing. In this way, a reservoir (drop) for filtered particles can be provided in the housing, for example. Furthermore, the stability of the housing can be improved in this way. Preferably, the filter membrane is arranged on the housing in such a way that a symmetry suitable for simple wiping movements is achieved. For example, the housing may also have a conical shape. In this case, the wiper can be moved on the surface of the filter membrane by a simple mechanism. In this way, a simple configuration of the filter system can also be achieved when the wiper is provided.

Preferably, the housing of the filter system is configured to be rotationally symmetrical about an axis. The fluid flow direction is preferably from the inside to the outside. Accordingly, the wiper may be located inside the housing. The filtered particles may also accumulate inside. Thereby, simple maintenance can be achieved. For example, when the amount of filtered particles in the housing is sufficiently large, the entire housing and its contents can be removed without the wiper and without other internally located components. Nevertheless, it is also conceivable to provide an outside-in fluid flow direction. Here, the above-described components need to be disposed on the other side of the filter membrane, similar to their technical action.

The first retaining means and/or the second retaining means preferably comprise a fluid supply. Accordingly, the fluid to be filtered can be inserted axially into the filter system by means of the retaining devices. As a result, no separate supply is required, and the filter system can be constructed in a particularly compact manner. This embodiment is particularly advantageous in case the filter system has a substantially cylindrical housing. In this case, the holding devices can be arranged on the top and bottom side of the housing, respectively. Here, both the first holding means and the second holding means may comprise a fluid supply. This may facilitate a particularly uniform delivery of the fluid to be filtered to the filter membrane.

Preferably, the tensioning element is formed by a spring element arranged between the first holding means and the second holding means. The tensioning element may be, for example, a helical spring which is in direct or indirect contact with the first and the second holding means. For example, the tensioning element may be disposed outside the filtering membrane such that the tensioning element is not in contact with the fluid. A particularly durable construction of the tensioning element can thereby be achieved. Alternatively, the tensioning element may also be provided in the filter system and arranged on the upstream side with respect to the fluid flow of the filter membrane. The force exerted by the tensioning element on the holding means can thus be directly introduced to the point at which the filter membrane is in contact with these holding means. In this way tension inside the filter system can be avoided.

In the case of a filter system having a cylindrical housing, the holding means can each be formed by two coaxial rings. The filter membrane may form part of a cylindrical housing between the rings. In the case of an internal application of fluid pressure, the filter membrane can initially deform under its own elasticity and form a substantially annular arch between the rings. Axial tension applied to the first and second retaining means by the tensioning element may cause the retaining means to axially compress apart. Thus, the membrane doming can be suppressed. Furthermore, additional radial forces can be exerted on the wiper that may be provided by the tensioning element, by the geometry or design dimensions of the filter membrane. This ensures that the wiper operation can be effectively achieved even if the internal pressure in the filter system is high.

The filter system preferably has a truncated cone-shaped housing, wherein the filter membrane is preferably arranged at least in sections on the circumference of the housing, and wherein the first holding device is preferably smaller in size than the second holding device. The housing may have a truncated cone shape in cross section along the axis of symmetry of the housing. The first retaining means may be arranged on such side of the housing: the cross-section of the housing is smallest on this side. The second holding means may be arranged on opposite sides of the housing, on which opposite sides the cross section of the housing is largest. The filter membrane may be configured to correspond to the outer contour of the truncated cone shape and be tensioned (or fixed) between the perimeter of the first retaining means and the perimeter of the second retaining means. In the case of a wiper arranged in the housing, the wiper may have a curved shape so as to substantially correspond to the ideal contour of the truncated cone-shaped housing. The second holding device may have a fluid supply through which fluid to be filtered can be fed into the interior of the filter system. Furthermore, the second holding device may have a carrier web/carrier stripThe carrier strip projects into the filter system from the second holding device in the direction of the first holding device. The carrier strip can rotatably carry the wiper which may be provided. The wiper drive can extend through the second holding device. The tensioning element may be arranged between the carrier strip and the first holding means. Further details regarding the carrier strip are described below.

Preferably, the first retaining means and the filter membrane are detachably/releasablyArranged or arrangeable on the second holding means. In other words, the first holding means can be held together with the filter membrane from the secondThe device is removed. This has the advantage that the filter membrane can be removed together with the first holding means and can be disposed of together with the particles in case the filter system is completely filled with filtered particles. This makes it possible to empty the filter system particularly simply. In other words, the user does not have to remove the filtered particles from the filter system in this way, but rather the particles can be removed and disposed of, for example, by means of a bag made of a filter membrane (for example in the case of a truncated cone-shaped housing). In order to fasten the first holding device and the filter membrane to the second holding device, a catch mechanism may be provided on the filter membrane and the second holding device. It is furthermore conceivable that the bayonet lock device enables fastening and release of the filter membrane and the first and second holding means. Preferably, the wiper which may be provided remains on the second holding device and/or on the carrier strip and is not removed together with the first holding device and the filter membrane.

Preferably, the filter membrane and/or the first holding device has a bayonet lock, by means of which the first holding device and the filter membrane can be fixed in the second holding device. The bayonet lock has the advantage that the first retaining means and the filter membrane can be fixed or released by rotation about the symmetry axis of the filter system. A particularly simple operation is thereby achieved. At the same time, in the assembled state, a reliable hold is ensured even in the event of an increase in the fluid pressure in the filter system. Furthermore, it can be ensured by a bayonet lock: the two releasable elements can be released from one another or secured to one another without having to rotate far, thereby protecting the structure in which the filter system is disposed from damage. The filter can thus also be arranged in a narrow region of the water-conducting household appliance, which has only limited accessibility.

The filter system preferably further comprises a wiper element, which is fixedly connected to the first holding device and to the filter membrane and rests against the second holding device in the operating state. The operating state may be a state in which the first holding means and the filter membrane are mounted on the second holding means. The scraping element may be used to ensure that all particles present in the filter system can be removed together with the first holding means and the filter membrane. The operation of the first holding means and the filter membrane (together also referred to as particle bag) can thereby be simplified, as particle falling out is avoided. In case a wiper is provided in the filter system, the wiping element may also be scraped past the wiper, so that particles located on the wiper are also removed together. This enables the filter system to be reliably cleaned of particles. Furthermore, the scraping element prevents the user from merely pouring out and/or washing out the particle bag and subsequently assembling it again to the filter system. This is undesirable because it is desirable to dispose of the particles (especially microplastic) by household waste rather than supplying them back to the water circuit.

The wiping element preferably has an opening. The opening of the wiper element may substantially correspond to the outer contour of a wiper disposed in the filter system (i.e., the contour of the wiper in a cross-sectional view of the wiper). Thus, with the first holding means removed together with the filter membrane, the wiping element may almost completely wipe the outer periphery of the wiper to remove all particles from the wiper. In other words, the opening of the wiper element can be configured such that a wiper provided in the filter system can pass through. It is desirable that the wiping element wipes the wiper to carry away all particles located on the wiper. Thus, the size of the opening may be smaller than the size of the wiper. In this case, the constituent material of the wiper element may have elastic deformability.

The wiping element is preferably constructed flexibly. The wiping element can thus also have any opening which can be adapted by flexibility to the possible inner surface shape of the wiper and/or the filter membrane which may be provided. In this way, the pressure between the wiping element and the element to be wiped can also be increased.

Preferably, the filter system comprises a carrier web which rotatably supports the wiper element, wherein the carrier web is arranged such that it is surrounded at least in sections by the filter membrane. The carrier strip can be formed integrally with the second holding device and can protrude from the second holding device into the interior of the filter system. The carrier strip may extend along an axis of symmetry of the filtration system. Furthermore, the carrier strip can be designed such that it can rotatably support a wiper which may be provided in the filter system. The carrier web may furthermore define a wiper area, wherein the carrier web defines a first stop for the wiper on one side and a second stop for the wiper on the opposite side, wherein the wiper can oscillate back and forth between the two stops. In other words, the wiper may perform a pendulum motion (pendelbewegun).

The carrier strip preferably defines a wiper area within the filtration system. Preferably, the carrier strip defines a particulate reservoir within the filtration system that is not scraped by the wiper. In other words, a particle reservoir can be formed between the two wiper stops of the carrier strip. During operation of the filtration system, the wiper may supply particles scraped from the filtration membrane to the reservoir and compress the particles in the reservoir by the continuously supplied particles. This prevents particles from migrating back and forth over the filter membrane without stopping, which could damage the filter membrane.

Preferably, the carrier strip is constructed integrally with the second holding device. This ensures that the carrier webs are continuously arranged in the same location. Furthermore, individual components of the filter system can be reduced and thus the production can be effected efficiently.

Preferably, the tensioning element is arranged on the carrier strip such that the tensioning element is arranged between the carrier strip and the first holding means. The carrier strip can protrude from the second holding device into the interior of the filter system in such a way that the outer end of the carrier strip is spaced from the first holding device in the filter system. A tensioning element (for example a helical spring) can be arranged between the outer end of the carrier strip and the first holding device. For this purpose, the carrier strip may have a projecting pin or cylindrical section at its outer end, on which a coil spring is inserted, for example. It is conceivable that the first holding means only have to have a small recess or the like in contact with the other end of the helical spring. In this way, a particularly simple construction of the filter system can be achieved.

Preferably, the second holding device has a through-opening through which the drive of the wiper extends. The wiper driver may be a shaft on which the wiper is located. Such a shaft may extend through the opening through the second retaining means. The through-hole may have a seal that seals between the second holding device and the wiper driver. This ensures that no fluid escapes from the filter system via the passage.

The tensioning element may preferably be formed by a helical spring. In this way, the force exerted by the tensioning element can be defined particularly simply and the tensioning element can be constructed simply.

The filter system is preferably designed such that the pretension can be varied as a function of the fluid pressure in the filter system. In other words, fluid pressure may be utilized to create axial tension. The diameter and the length of the housing of the filter system can be adapted to one another in such a way that the fluid pressure generates an axial pressure on the first and/or the second holding device, which axial pressure is integrated into the tensile stress acting on the filter membrane. In this way, by the geometry of the housing of the filter system, the filter membrane can be brought into the correct radial tension for each pressure value within the filter system. This is particularly advantageous because the radial pressure is adjusted in accordance with the current fluid pressure within the filtration system. That is, as the clogging of the filter membrane increases, the wiper pressure acting on the filter membrane also automatically increases. In this way the filter membrane surface can be cleaned effectively by the wiper. Fluid pressure may also be used with the spring and assisted in the generation of radial pressure. It is furthermore conceivable to provide a pressure sensor on the upstream side of the filter membrane, said pressure sensor being provided for measuring the fluid pressure upstream of the filter membrane. The tensioning element can then be controlled in dependence on the measured pressure. In this way, for example, a defined pretension can be assigned to a defined pressure value, so that a sufficient tensioning of the filter membrane can always be ensured. The control of the tensioning element can be effected, for example, by mechanical means which can influence the tensioning element (for example, by means of a lever arm). In addition, such control may also be realized by electronic control. For example, the tensioning element can be actuated, for example, by a servomotor, in order to change the pretension.

According to another aspect of the present invention there is provided a water-guiding domestic appliance comprising: a processing chamber; a fluid supply portion that can supply a fluid to a process chamber; and a fluid outlet which can lead fluid out of the treatment chamber, wherein the filter system according to any of the preceding embodiments is provided in a water-conducting household appliance (in particular a fluid outlet).

According to another aspect of the invention there is provided a method for cleaning a fluid by a filtration system, in particular according to any one of the above-mentioned construction schemes, wherein the method comprises:

filtering the fluid through a membrane filter of the filtration system to filter particles from the fluid:

the membrane filter is tensioned by means of a first and a second holding means of the filter system.

The method preferably includes operating a wiper of the filtration system to remove particles from the filtration surface of the filtration membrane.

Preferably, the method comprises releasing the first holding means and the filter membrane from the second holding means; and removing the first holding means and the filter membrane from the second holding means, wherein the filtered particles remain on the filter membrane.

According to a further aspect, there is provided the use of at least one tensioning element to tension a filter membrane of a filter system (in particular according to any one of the above-described construction schemes).

According to one aspect of the invention, two important factors that occur in the operation of the filtration system can cause deformation of the filtration membrane: on the one hand, the filter membrane is locally tensioned on the wiper edges, as a result of the wiper pressing onto the exposed filter membrane surface. This results in the desired linear compression between the filter membrane and the wiper edge, which can provide the compressive force required to remove the particles from the membrane surface. The force should also be sufficiently great to capture the filtered particles by the wiper edge and move them to one side. The wiper edge preferably has a curved course, so that the tensile force of the film on the wiper edge is represented by a somewhat uniform pressing force on the wiper edge course.

In operation, the pressure of the fluid to be filtered acts globally on the filter membrane, which deforms the membrane, that is to say in the direction away from the wiping edge. The fluid pressure thereby reduces the wiper pressure with which the wiper is pressed against the filter membrane. This may lead to lifting of the filter membrane from the wiping edge. That is to say that the pressing force of the wiper edge against the membrane is reduced and, in addition, the surface of the filter membrane that is scraped by the wiper during operation of the filter system is also reduced due to possible (at least sectional) contact losses. This may lead to a deterioration in the efficiency of the wiper. Typical ranges of fluid pressure in such filtration systems are a few centimeters up to two meters of water, depending on the degree of filter clogging. That is, the fluid pressure may thereby be expanded to approximately two orders of magnitude.

According to one aspect of the invention, the filter membrane is formed from a gauze material in the case of a conical shell, so that a joint (Stoβstelle) is formed along the strip edges (Streifen) of the conical periphery, at which joint the two filter membrane edges are connected to one another. The engagement point is preferably located below the carrier strip during operation of the filter system, since the wiper does not scrape over this region. Furthermore, a particle reservoir of the filter system can be provided at the junction. The filter membrane is preferably designed such that it is formed as a flexible element. The gauze material may comprise polyester and/or polyamide. Furthermore, the filter membrane may comprise glass fibers, non-woven fabrics, knitted fabrics, injection molded films, PET, teflon, carbon fiber fabrics and/or glass fibers. The joining points of the two filter membranes can be glued, welded, sewn or injected, for example, in an overlapping manner, into the structure formed by the support ring and the support plate. Preferably, the junction may be tangential to the housing of the filtration system. Furthermore, the edges of the junction of the filter membranes may be folded radially inwards and then glued, welded, sewn or injected into a certain part of the housing of the filter system. The edges can also be folded radially outwards and connected to one another as described above. In addition, the filter membrane can also be produced without engagement/impact (stoβfrei). This can be achieved, for example, by knitting without joining. In addition to the textile, the filter membrane can also be formed from a knitted fabric, i.e. the cylinder or also the cone can be produced almost seamlessly, for example using a circular knitting machine.

In addition, the filter membrane may also be composed of a membrane with very finely pressed-in pores. Such a film may be, for example, a plastic film.

According to another aspect of the invention, the filter membrane may include a wiper cap. The wiper cap rests on the second holding device in the operating state of the filter system. With the wiper driver off, the wiper may remain in a defined position. For example, the wiper may rest in the middle above a carrier strip that may be provided (i.e., in the direction of gravity of the operating position of the filter system). The wiper cap is a closed face (except for the fluid supply). A through-hole of the carrier strip and a slit for the wiper to pass through are provided. All openings are provided with a scraping lip, for example, so that particles adhering to the wiper and carrier strip can be scraped off first and removed together with the particle bag when the particle bag (i.e. the particle-filled filter bag) is removed. Such a wiper cap also makes it difficult to inhibit cleaning the filter bag under the faucet for reuse.

The tensioning element, such as a spring, has two important functions in the above-described embodiments. First, an axial tension is created which is responsive to the arching of the filter membrane caused by the fluid pressure, and second, the spring is self-flexing to respond to the pulling forces exerted by the wiper along the perimeter. The first holding device performs a synchronous oscillating movement with the wiper in a rotary movement. The guide system and the spring are configured in such a way that this pivoting movement is possible with slight axial compression.

The first holding means, the second holding means and/or the carrier strip may preferably be made of plastic. The filter membrane can be fixed at least to the first holding means, for example by means of encapsulation injection molding. Polycarbonate, PEE, PP and/or PET are suitable plastics.

An advantage of the present invention is that a simple filtration system can be achieved by minimally constructing the filter as a particle bag. Simple manipulation (i.e., removal of the particle bag) wins the acceptance of the user. In addition, the filtration system has a simple, inexpensive and efficient construction. In addition, little material needs to be replaced, thereby providing an attractive cost structure. The pressing force between the filter membrane and the wiper can be configured uniformly in such a way that the filter system can be fault-tolerant against disturbances, such as larger particles being pushed between the membrane and the wiper. Furthermore, a uniform force distribution with respect to a system with radial spring means can be achieved.

Individual features may be combined with other features or with other embodiments to thereby constitute new embodiments. The embodiments and advantages mentioned in connection with the individual features also apply analogously to the new embodiment. The advantages and constructional solutions already explained in connection with the device are likewise applicable to the method and vice versa.

Drawings

Preferred embodiments are described below exemplarily based on the drawings.

Fig. 1A and 1B schematically show a filter system according to an embodiment of the invention in longitudinal and cross-section.

Fig. 2 schematically shows the basic principle of a wiper.

Fig. 3A and 3B schematically show a filter system according to an embodiment of the invention in longitudinal and cross-section.

Fig. 4 schematically shows a cross section of a filter system according to an embodiment of the invention.

Fig. 5A and 5B schematically show a filter system according to an embodiment of the invention in longitudinal and cross-section.

Fig. 6 schematically shows a longitudinal section of a filter system according to an embodiment of the invention.

Fig. 7 shows a schematic perspective view of a water-guiding domestic appliance according to an embodiment of the present invention.

Detailed Description

Fig. 1A shows a schematic cross-sectional view of a filter system 1 according to an embodiment of the invention along the longitudinal axis of the filter system 1. The filter system 1 is configured for filtering particles 7 (not shown in fig. 1) from a fluid. For this purpose, the filter system 1 of the present embodiment has a filter membrane 2, which filter membrane 2 is held on one side by a first holding device 3 and on the opposite side by a second holding device 4. The first holding means 3 and the second holding means 4 are displaceable relative to each other. In this way the filter membrane 2 can be tensioned. For this purpose, the filter system 1 may have a tensioning element 5, which tensioning element 5 may exert a pretension on the first holding device 3 and/or the second holding device 4, so that the filter membrane 2 is always tensioned. In this way, arching of the filter membrane 2 can be avoided, as a result of which the filter system 1 can be constructed particularly compactly.

A cross section through the filter system 1 is shown in fig. 1B. The position of the cross section shown in fig. 1B is characterized in fig. 1A by a dash-dot line and two arrows. Accordingly, the filter system 1 of the present embodiment has a cylindrical outer shape. The tensioning element 5 is located outside the interior of the filter system 1 in the present embodiment. As a result, the tensioning element 5 cannot come into contact with the filtrate and/or the fluid to be filtered and thus increases the service life.

When the pores of the filtration membrane 2 are particularly small of about 50 μm, mechanical cleaning (i.e., scraping) of the filtration surface of the filtration membrane 2 may be necessary in order to be able to ensure sufficient filtration performance at a certain time.

Fig. 2 schematically illustrates the principle of the wiper wiping. Here, the wiper 6 is capable of reciprocating on the surface of the filter membrane 2 (see horizontal arrow in fig. 2). During which fluid can flow through the filter membrane 2. As indicated by the thick vertical arrows in fig. 2, the fluid flow direction is from top to bottom. Accordingly, the wiper 6 is arranged such that it is employed on the upstream side of the filter membrane 2 (i.e. the side on which the particles 7 are blocked by the filter membrane 2).

Fig. 3A schematically shows a longitudinal cross-sectional view of a filter system 1 according to an embodiment of the invention. The filter system 1 of the present embodiment essentially corresponds to the embodiment shown in fig. 1, with the difference that in the present embodiment, the wiper 6 is provided and the tensioning element 5 is configured differently.

The wiper 6 is movably supported inside the filter system 1. The wiper 6 is movably supported inside the filter system 1. The wiper 6 is preferably dimensioned relative to the filter membrane 2 such that the wiper 6 has a protrusion (Vorhalt). The protrusion means that the wiper 6 protrudes beyond the desired shape of the filter membrane 2. In other words, the wiper 6 is slightly pressed into the filter membrane 2. Thereby, the pressing force between the wiper 6 and the filter membrane 2 can be ensured. Preferably, the wiper 6 has a paddle-like shape. The wiping edge of the wiper 6 is curved in the longitudinal direction of the filter system 1, so that the pressing force between the wiper 6 and the filter membrane 2 is distributed uniformly over the wiping edge. In this way, high partial pressures between the wiper 6 and the filter membrane 2 can be avoided, which increases the service life of the filter membrane 2.

Fig. 3B shows a cross section at the position shown in fig. 3A (dot-dash line). In fig. 3B, it can be seen that the wiper 6 causes a slight bulge in the filter membrane 2. This is due to the fact that the wiper 6 is in relation to the aforesaid protrusion of the filter membrane 2. The rotating arrow in fig. 3B indicates that the wiper 6 can perform a pendulum movement or continuously move on an endless track. In this way particles (not shown in fig. 3A and 3B) are cleaned from the surface of the filter membrane 2.

The tension element 5 of the present embodiment is a coil spring extending outside the filter membrane 2. More precisely, the first holding means 3 and the second holding means 4 are axially pressed apart by a helical spring 5. The filter membrane 2 is thus tensioned in the axial direction, in particular on the wiper 6. This suppresses doming (caused by the fluid internal pressure of the filtration system 1). In other words, the pressing of the wiper 6 onto the filter membrane 2 can thereby be maintained.

Fig. 4 shows a longitudinal section of a filter system 1 according to another embodiment of the invention. The filter system 1 of the present embodiment differs from the previous embodiments in that the filter membrane 2 constitutes a truncated cone-shaped housing. Furthermore, this embodiment has a carrier web 10, which carrier web 10 rotatably supports the wiper 6. Furthermore, a tensioning element 5 is arranged on the outer end of the carrier strip 10 and is pressed against the first holding device 3. The carrier strip 10 is constructed integrally with the second holding device 4. The wiper 6 is curved corresponding to the inner peripheral shape of the filtering membrane 2. In this embodiment, the wiper 6 likewise protrudes beyond the ideal peripheral line of the cone (i.e. has a protrusion). The wiper drive (or wiper shaft) extends through the second holding device 4. This embodiment also has a wiper element 9, which wiper element 9 rests on the second holding device 4 in the installed state (operating state) shown in fig. 4.

Fig. 5A and 5B show the filtration system 1 of fig. 4. Furthermore, in the filter system 1 shown in fig. 5A and 5B, the first holding device 3 can be removed from the second holding device 4 together with the filter membrane 2 and the wiper element 9. In fig. 5A and 5B, the first holding device 3, the filter membrane 2 and the wiper element 9 have been removed. These three elements may also be referred to as filter bags or particle bags. That is, if the filtration system 1 is filled with particulates, the user can remove the filter bag and dispose of it with the particulates. A new filter bag may then be installed and operation resumed. Fig. 5B shows a cross section through the filter system 1 of fig. 5A. It can also be seen that the carrier strip 10 constitutes a stop for the wiper 6. The wiper 6 of the present embodiment can therefore perform a pendulum movement between the two stop sides of the carrier strip 10. Furthermore, the carrier strip 10 constitutes a space inside the filter system 1 which can be used as a particle reservoir 11. Accordingly, particles may be aggregated in the space.

Fig. 6 schematically shows a filter system 1 according to an embodiment of the invention. More precisely, a state in which the filter system 1 is filled with particles 7 is shown in fig. 6. Thus, the user can remove the filter bag and dispose of it with the particles 7. The wiping element 9 ensures that the wiper 6 as well as the carrier strip 10 are scraped off in order to carry away particles 7 that may adhere thereto. The second holding device 4 can also be referred to as a module carrier and contains all the important mechanical components, such as: the support and stop of the wiper 6, the tensioning element 5 (for example an axial compression spring), the possible means for fastening the particle bag and the supply for the fluid carried by the particles. The module carrier is preferably removable in its entirety from the water-conducting household appliance, so that it can be cleaned without difficulty.

In the case of particle bags, the filter membrane 2 may be a truncated cone shaped gauze bag with the first holding means 3 on the front side and the scraping element 9 or support ring on the rear side. In order to fasten the particle bag, the wiper ring 9 or the support ring can be embodied with suitable connection possibilities (e.g. screw thread, bayonet connection, screw connection, clamping connection, etc.). The first holding device 3 can transmit the spring pressure of the tensioning element 5 to the filter membrane 2.

In fig. 6 it is shown by means of dashed arrows how the particle bag together with the filtered particles is pulled down from the second holding means 4 and disposed of as a whole. The second holding device 4 with mechanical components is designed as free of undercuts as possible in the removal direction (hinterschnittsfrei), so that the particle bag together with the particles 7 can be removed without difficulty, without leaving behind a large particle accumulation on the second holding device 4 (or components thereof).

Fig. 7 shows a schematic perspective view of a water-guiding domestic appliance 100 with a treatment chamber 101. Further, the water-guiding domestic appliance 100 has a fluid supply 102, which fluid supply 102 can supply a fluid to the treatment chamber 101. Particles 7 (e.g. laundry) may be treated in the treatment chamber 101. The filtration system 1 according to any of the above configurations may be arranged on a drain or recirculation line that may conduct fluid away from the process chamber 101.

Claims

1. A filtration system (1) for a water-conducting household appliance for filtering particles (7) from a fluid, wherein the filtration system (1) comprises:

-a filter membrane (2) configured for filtering particles (7) from a fluid;

-first holding means (3) for holding the filter membrane (2) on a first side of the filter membrane (2);

-second holding means (4) for holding the filter membrane (2) on the side of the filter membrane (2) opposite to the first side of the filter membrane (2); and

-a tensioning element (5) configured for applying a pretension to the first holding device (3) and/or the second holding device (4) in order to tension the filter membrane (2).

2. The filtration system (1) according to claim 1, wherein the filtration system (1) comprises a wiper (6) configured for movement relative to the filtration membrane (2) to scrape off particles (7) blocked by the filtration membrane (2).

3. The filter system (1) according to any one of the preceding claims, wherein the tensioning element (5) is constituted by a spring element arranged between the first holding means (3) and the second holding means (4).

4. The filter system (1) according to any of the preceding claims, wherein the filter system (1) has a truncated cone shaped housing,

wherein the filter membrane (2) is arranged at least in sections on the circumference of the housing and

wherein the first holding means (3) has a smaller size than the second holding means (4).

5. The filtration system (1) according to any of the preceding claims, wherein the first holding means (3) and the filter membrane (2) are releasably arranged or arrangeable on the second holding means (4).

6. The filter system (1) according to claim 5, wherein the filter system (1) further has a wiper element (9) which is fixedly connected to the first holding device (3) and to the filter membrane (2) and rests against the second holding device (4) in the operating state.

7. The filter system (1) according to any one of claims 2 to 6, wherein the filter system (1) comprises a carrier web (10) which rotatably supports the wiper (6), wherein the carrier web (10) is arranged such that it is surrounded at least in sections by the filter membrane (2).

8. The filtration system (1) according to any of the preceding claims, wherein the filtration system (1) is configured such that the pretension can be varied in dependence of the fluid pressure in the filtration system (1).

9. A water-conducting household appliance (100), comprising:

a processing chamber (101);

a fluid supply (102) that can supply a fluid to the process chamber (101); and

a fluid discharge portion which can lead out fluid from the process chamber (101);

the filtration system (1) according to any of the preceding claims, wherein it is provided in the water-conducting household appliance (100), in particular in the fluid discharge.

10. Method for cleaning a fluid by means of a filtration system, in particular a filtration system (1) according to any one of claims 1 to 8, wherein the method comprises:

-filtering the fluid through a membrane filter (2) of the filtration system (1) to filter out particles (7) from the fluid:

the membrane filter (2) is tensioned by means of a first holding device (3) and a second holding device (4) of the filter system (1).

11. The method according to claim 10, wherein the method comprises:

-operating the wiper (6) of the filtration system (1) to remove particles (7) from the filtration surface of the filtration membrane (2).

12. The method according to claim 10 or 11, wherein the method comprises:

releasing the first holding means (3) and the filter membrane (2) from the second holding means (4); and

-removing the first holding means (3) and the filter membrane (2) from the second holding means (4),

wherein the filtered particles (7) remain on the filter membrane (2).