Filter cartridge for filtration of liquids

Abstract

A filter cartridge for filtering liquids has a filter chamber housing (3) having an inlet opening (7) and an outlet opening (8) for allowing liquid to flow through the filter chamber housing (3). At least one filter medium (4) for filtering the flowing liquid is disposed within a filter chamber volume (5) surrounded by the filter chamber housing (3). The filter cartridge includes a compression device (2) containing at least one compression element (9) through which compression force can be applied to the filter medium (4) to compress the filter medium (4). The filter cartridge has two filter chamber zones (6), each filled with particulate filter medium (4), and the compression device (2) is disposed between the two filter chamber zones (6). The compression device (2) forms a separation device (15) by which the two filter media (4) in the two filter chamber zones (6) are separated from each other, the separation device (15) allowing fluid communication between the filter chamber zones (6) or being bypassed by fluid communication. The compression device (2) is designed to expand and thus apply compressive force to the filter medium (4) in each of the two filter chamber areas (6). At least one compression element (9) is disposed between two pressure elements (10), each pressure element being pressed into its respective filter chamber area (6) by the expansion movement.

Description

Technical Field

[0001] The present invention relates to a filter cartridge for filtering liquids, wherein the filter cartridge has a filter chamber housing having an inlet and an outlet for liquid to flow through the filter chamber housing, wherein at least one filter medium for filtering the flowing liquid is disposed within a filter chamber volume surrounded by the filter chamber housing, and wherein the filter cartridge has a compression device containing at least one compression element through which compression force can be applied to the filter medium to compress the filter medium. Prior Technology

[0002] Single-layer or multi-layer liquid filtration systems are generally used to treat drinking water, with filter cartridges containing activated carbon typically used as the first layer of filtration to reduce the concentration of impurities such as chlorine, suspended solids, and heavy metals (like lead). Optionally, the filter cartridges contain ion exchange resins to reduce the concentration of calcium and magnesium ions, resulting in lower water hardness. Filtered water typically has a better taste and improved quality for human consumption. The filter media is usually a granular solid material, with particles having regular shapes (e.g., spherical), irregular shapes, or a mixture of both. The filter media is typically configured as a loose packing material within the filter chambers inside the filter cartridge housing. The filter cartridge housing can be designed in various shapes. For example, elongated cylindrical filter cartridges are known. In such cartridges, liquid enters the filter chamber housing through an inlet opening and flows through the filter media confined within the housing. The liquid filtered by the filter media then exits the filter chamber housing through an outlet. However, other shapes of filter cartridges are also conceivable, such as elongated elliptical, conical, or rectangular box-like shapes.

[0003] During filter cartridge operation, the flow of liquid through the granular filter media can create undesirable bypasses or channels within the media. Once such channels form, the liquid tends to flow through them, resulting in less contact between the liquid and the filter media and increased wear on the media surrounding these channels. This reduces filtration efficiency. These channels within the filter media are particularly formed when the flow rate of liquid through the filter media increases. At high flow rates, a pressure drop occurs along the flow path between the filter cartridge inlet and outlet. The resulting dynamic pressure and pressure drop locally compress the filter media, causing the granular filter media to settle and compress. This causes a change in the liquid flow path. Due to the localized compression of the filter media, the liquid flow rate decreases to almost zero in some areas, while in other areas, a correspondingly high volume of liquid flow rate is generated, resulting in channel formation. The liquid to be filtered can flow through these channels with low resistance. In this case, the liquid to be filtered flows directly into the intake area with little or no contact with the filter media, resulting in impurities remaining in the filtered water.

[0004] To prevent channel formation within the filter cartridge, an expansion medium is used to apply pressure to the filter media, compressing it. Specifically, a non-woven fabric made of polyethylene terephthalate (PET) is used as the expansion medium. The non-woven fabric is configured as one or more layers in contact with the filter media in the cartridge, thus compressing the non-woven layers at the beginning of the cartridge's service life. Due to the restoring force of the compressed non-woven layers, a compressive force is applied to the adjacent filter media, reducing channel formation during cartridge use. The restoring force generated by the non-woven layers depends on the thickness of the non-woven layers, the degree of compression, and the composition and fiber thickness within the non-woven fabric. However, the restoring deflection of the non-woven layers is very small relative to the restoring force, resulting in a small compressive force applied to the filter media. Furthermore, the restoring force of the non-woven layers depends on the cartridge's usage time, and therefore decreases sharply or disappears completely after prolonged use. In particular, very small filter media particles can escape the filter media housing during packaging, transportation, or cartridge use, causing the filter media to shrink and facilitating channel formation within it.

[0005] Furthermore, some filter media undergo mechanical or chemical changes during use, thus experiencing volume changes, etc. These volume changes can be increases or decreases in volume, depending on the filter media in question and the process by which the filter media is altered during use. Therefore, expansion media, and especially non-woven layers, are preferably designed to accommodate these volume changes during use.

[0006] When nonwoven fabrics are cut from nonwoven sheets into individual nonwoven layers, varying nonwoven thicknesses at the beginning or end of the sheet can cause jamming or misalignment within the production line. This results in production downtime or time-consuming machine resetting. To ensure consistent quality in terms of nonwoven layer thickness and therefore consistent resilience during filter cartridge production, sophisticated and costly quality testing accompanying batch production is necessary. Furthermore, only a limited number of suppliers can manufacture or supply suitable nonwoven sheets for filter cartridges. This poses a high risk of supply bottlenecks if suppliers experience malfunctions or production stoppages.

[0007] Disadvantages typically include contamination of non-woven fabrics with bisphenol A (BPA) or catalysts such as antimony. Even small amounts of BPA can contribute to the development of diseases such as diabetes, obesity, thyroid dysfunction, developmental disorders (especially in children), and human infertility. Therefore, complex, continuous migration testing is required to determine and control BPA levels and the total amount of migration from or into food contact materials. Furthermore, non-woven fabrics made of PET mean that the different materials used to manufacture filter cartridges can only be separated through a complex and costly recycling process.

[0008] If the filter media comprises two different types of filter materials, such as activated carbon and ion exchange resin, these different types of filter materials are either mixed in a single filter chamber or configured in separate filter chambers. To avoid forming unwanted channels, each filter chamber requires a corresponding nonwoven layer, which applies compressive force to its respective filter material. Due to the different properties of the individual filter materials, the characteristics of the nonwoven layers can vary and are therefore different.

[0009] US Patent Application No. US2009 / 0008318A1 discloses a dual-module filtration system that, in addition to a pre-filter, employs two or more filter layers. For chemical mitigation, organic filtration, and deionization modules comprising a bed of some form (e.g., an activated carbon bed or a resin bed), these modules preferably include bed limiters disposed on both sides of the bed. Preferably, the bed limiters are made of a porous hydrophobic material. In an improvement, the limiters are made of a hydrophobic foam material. The hydrophobic foam material applies axial pressure to the bed in both directions and is used to optimize water flow on the purified bed without any manifold. The volume or thickness variation of the hydrophobic foam bed limiter is also inversely proportional to the volume variation of the purified bed to compensate for changes in the purified bed volume, which prevents channel formation by applying consistent axial pressure in both directions of the purified bed.

[0010] US Patent Publication No. 3,831,754 discloses an apparatus comprising means for guiding a liquid continuously through two or more filter elements. In one embodiment, a pair of cartridges are provided in a flow guide unit. The cartridges used in this apparatus employ an adhesive of a matrix material that is sufficiently elastic to allow dimensional variations in the aggregated particles to be translated into corresponding and generally reproducible variations within the cartridges. Furthermore, the aggregated particles are preferably aggregated in a manner in which substantially their entire surface area is freely exposed to contact the fluid to be treated. The inlet of the treatment apparatus is located at the axial end opposite the outlet, thus there is no fixed mechanical connection between the upper plate engaging the bottom end cap of the upper cartridge and the lower plate engaging the upper end cap of the lower cartridge. A seal is provided at the outer periphery of the upper plate, while an opening is located at its center to provide communication into an axially extending interior opening in the lower cartridge. The central portion of the lower plate covers the axial guiding opening in the lower cartridge. These plates are held near their associated filter cartridges by springs that push the plates into liquid-tight contact with the seal, thereby preventing radial fluid flow into the filter cartridges. A size change detector is placed between these plates.

[0011] One object of the present invention is to provide a filter cartridge that reduces, in a cost-effective manner, the formation of unwanted channels within particulate filter media over an extended service life of the filter cartridge. Summary of the Invention

[0012] The present invention relates to a filter cartridge for filtering liquids, characterized in that at least one compression element is disposed between two pressure elements, each of which is pressed into its respective filter chamber area by an expansion movement.

[0013] The expansion movement can be achieved, for example, through a compression device that extends at least partially into the filter chamber housing and through a balloon-shaped compression element, whose volume increases due to the internal pressure applied to it. The balloon-shaped compression element can be a balloon made of an elastic and pressure-resistant material filled with compressed air. The compressed air inside the balloon generates an outward force, causing the balloon to expand and preventing cavities or channels from forming in the filter media within the two adjacent filter chamber zones. Therefore, compression force is applied to each filter medium without requiring a non-woven layer. Furthermore, by positioning the compression device between the two filter chamber zones, only one compression device is needed to apply compression force to each filter medium within its respective filter chamber zone. Thus, using the compression device positioned between the two filter chamber zones, pressure can be applied to both filter media simultaneously.

[0014] To allow liquid flowing through the filter chamber housing from one filter chamber section to another, the filter cartridge includes fluid channels for bypassing a compression device disposed between the two filter chamber sections. If the compression device is formed by a balloon, such channels can be formed, for example by pipes, arranged along the inner wall of the filter chamber housing surrounding the balloon, providing fluid conduction between the two filter chamber sections. Each end of each pipe can be covered with a sieve to prevent the filter media from being carried through the pipes by the fluid. Alternatively, a toroidal balloon providing a channel through the open center of the toroidal balloon can also be used.

[0015] As described previously, the compressor can optionally not only provide compressive force to the two filter media confined within their respective filter chamber areas, but it can also be designed to perform a contraction movement if the volume of one or both filter media increases during the filter cartridge's service life. For some applications and filter media, this volume increase is considered beneficial or unavoidable, and the compressor should accommodate this increase. Thus, in conjunction with the expansion movement, the compressor can allow for resilient or springback compensation for any changes in the volume of the filter media within the two filter chamber areas that may occur, for example, during the use of the filter cartridge.

[0016] In one embodiment of the invention, the compression device is completely surrounded by the filter chamber housing. This means that the compression device is completely confined by the filter chamber housing, and no opening is needed within the filter chamber housing to apply the compressive force generated outside the filter chamber housing to the filter medium confined within the filter housing. Therefore, the expansion movement of the compression device can be primarily directed towards one or both filter chamber sections within the filter chamber housing. Consequently, the compressive force is applied to the filter medium in a particularly locked manner, resulting in particularly strong compression of the filter medium and effectively preventing the formation of any unwanted channels within the filter medium.

[0017] Because the compressor is completely enclosed by the filter chamber housing, the filter cartridge can be designed to be completely sealed relative to the compressor. There is no need for feedthrough openings to allow the compressor element into the filter chamber housing, nor for complex sealing systems to seal these openings. Furthermore, the compressor and filter chamber housing can be manufactured separately and assembled in a particularly time- and cost-effective manner. If the compressor is installed within the filter chamber housing before it is closed, the design and installation of the compressor allow for further processing and completion of the filter chamber housing manufacturing process. Therefore, the compressor, for example, should be able to withstand ultrasonic welding of pre-separated filter chamber housing components or should be installed in a way that allows the two separate filter chamber housing components to be locked together without damage or interference with the filter chamber housing manufacturing process.

[0018] The compression device can be loosely disposed between two filter chamber sections within the filter chamber housing. During the manufacturing process of the filter cartridge, a first filter medium is filled into the filter chamber housing, thereby forming a first filter chamber section. The compression device is then placed on top of the first filter medium, separating the first filter medium from the remaining space within the filter chamber housing. The remaining space can then be filled with a second quantity of filter medium, thereby forming a segmented filter chamber section through the compression device positioned between the two filter chamber sections.

[0019] According to an alternative embodiment of the invention, the compression device is detachably connected to the filter chamber housing. For this purpose, the compression device can be inserted into the filter chamber housing via a friction connection or a form-fit connection. A friction connection can be created, for example, through a spring-like connection between the compression device and the filter chamber housing. A form-fit connection can be formed, for example, through a snap-fit ​​connection. This makes it particularly easy to separate the compression device and the filter chamber housing by type for recycling or reprocessing purposes.

[0020] To enable expansion in the direction of the filter medium, the compression device can be at least partially made of an elastically deformable material. An elastic material deforms when subjected to a deformation force generated within the filter chamber and returns to its original shape when the deformation force is removed. Inelastic or rigid materials behave in a way that, when a deformation force is applied, the material does not deform or deforms only to a negligible degree. According to one possible aspect of the invention, the elastically deformable element is positioned between opposite sides of the compression element adjacent to the respective filter chamber regions. The elastically deformable element can be inserted between the two filter chamber regions in a compressed state, which will cause an outward expansion force generated by the compressed elastically deformable element towards each of the two filter chamber regions. The elastically deformable element can be made of, for example, rubber or elastic plastic material. Preferably, the elastically deformable element is chemically inert to the liquid or coated with a material that makes it chemically inert to the liquid.

[0021] To apply compressive force to a large volume of filter media, the compression device includes a pressure element that is pressed against the filter chamber area by an expansion motion. The pressure element can be, for example, a flat plate made of a rigid material. Preferably, the pressure element can move like a piston into the interior of the filter chamber area. The compression device with the pressure element must allow fluid conduction between two filter chamber areas containing two filter media. This can be achieved, for example, through more than one separate bypass pipe or through openings within the compression device, particularly openings within the pressure element, allowing free flow of fluid through the compression device.

[0022] Food-grade plastics, such as polyethylene terephthalate (PET), polypropylene (PP), or polyamide (PA), are suitable as rigid materials for pressure components. However, metallic materials such as stainless steel or aluminum can also be used to manufacture pressure components.

[0023] Alternatively, the compression device is designed such that both the compression element and the pressure element are made of the same material, whereby the compression element is designed to generate a deformation force toward the filter chamber area, and the pressure element is designed to transfer the generated force to a large surface of the filter media facing the compression device within its respective filter chamber area. Alternatively, the surface of the pressure element is smaller than the cross-sectional area inside the filter chamber area, and a deformable membrane is liquid-tightly mounted between the outer edge of the pressure element and the inner wall of the filter chamber housing surrounding the pressure element. Alternatively, the membrane can completely cover the cross-sectional area within the filter chamber area, and a pressure plate presses against the membrane and applies pressure through the membrane to the filter media in contact with the membrane. During the expansion movement of the pressure plate, the membrane deforms due to pressure, and compressive force is applied to the filter media.

[0024] According to an advantageous embodiment of the invention, the compression device includes one or more compression elements, each comprising a rigid portion and an elastically deformable portion, wherein the elastically deformable portion generates a force to move or pivot the rigid portion, thereby applying pressure to the filter medium. Thus, the elastically deformable portion can be small and located at a distance from the filter medium, while the rigid portion transfers the force to the filter medium. Several compression elements can be configured to be spaced apart from each other and distributed over a cross-sectional area within the filter chamber housing.

[0025] According to an advantageous embodiment of the invention, the compression device includes a spring device through which a pressure element is pressed into the filter chamber region, the spring device generating a compressive force acting on the filter medium. The spring device allows for the generation of spring pressure in a particularly simple manner, which in turn generates pressure acting on the filter medium. Depending on the position and arrangement of the spring device within the filter chamber housing, the spring device can be designed as, for example, a helical compression spring, a disc spring, a spiral spring, a parabolic spring, a membrane spring, or a leaf spring. Such springs are typically made of metallic materials. However, non-metallic springs, such as rubber springs or springs made of elastic plastic, are also suitable for use with the compression device. Furthermore, air springs or air springs can be integrated into the filter cartridge. Combinations of the above types of springs are also possible.

[0026] To apply a particularly uniform pressure to the pressure element in the direction of the filter medium, and according to embodiments of the invention, the spring device may include more than one spring element. The spring elements may be evenly distributed across the cross-sectional area of ​​the filter chamber. The spring elements may be designed as one of the spring types mentioned above.

[0027] To easily adapt the spring force to different filter media, methods of manufacturing filter cartridges may include arranging multiple spring elements in parallel or in series, such that the spring travel or spring force, or both, can be adjusted to suit the characteristics of the respective filter media filled into the filter chamber area. Parallel arrangement of multiple similar spring elements results in an increase in spring force. For example, arranging multiple helical compression springs in parallel results in an increased spring compression force. On the other hand, series connection of spring elements increases the spring travel. In the case of disc springs, parallel connection of spring elements is achieved by stacking disc spring elements in the same direction. Series connection of spring elements is achieved by alternately stacking individual disc springs. This makes adjusting the spring force and spring travel particularly easy.

[0028] The compression device forms a separation device by which two filter media in two filter chamber zones are separated from each other. According to the invention, the shape of the separation device matches the shape of the filter chamber housing, such that the first filter chamber zone can be completely isolated from the second filter chamber zone relative to the filter media contained in its respective first and second filter chamber zones. However, the separation device allows for fluid-conducting connections, or connections bypassed by fluid-conducting connections, such as more than one pipe or through-hole. Therefore, spatial separation of the two filter media is possible, which facilitates the subsequent recycling and reuse of the respective filter media made of different materials. Thus, several different filter media can be used in a single filter cartridge, with different filter media filling their respective filter chamber zones. Alternatively, a filter media containing activated carbon can be disposed in the first filter chamber zone, and a filter media containing ion exchange resin can be disposed in the second filter chamber zone. The two filter chamber zones are configured relative to each other such that liquid first flows through the filter media disposed in the first filter chamber zone and then through the filter media disposed in the second filter chamber zone. This results in particularly effective liquid filtration and a significant reduction in undesirable tastes and contaminating particles.

[0029] In another embodiment of the invention, the separating device includes two separating elements, with at least one spring device disposed between the two separating elements such that each of the two separating elements is pressed outward relative to the other. The volume between the two separating elements can be used to arrange or mount one or more spring elements of the spring device between the two separating elements made of a rigid material.

[0030] To allow liquid to flow through the separation element, the separation element includes one or more flow openings through which liquid can pass. The size of the flow openings is chosen such that particles of the particulate filter media cannot pass through them. This allows different filter media to be separated through the separation element, even though liquid can pass through it. In one embodiment, the separation element includes several flow openings that are uniformly or non-uniformly distributed across the cross-section of the filter chamber housing, so that the entire cross-section is utilized to allow fluid to flow from one filter chamber zone to another, which enables better and more efficient utilization of the filter media in each filter chamber zone.

[0031] According to one aspect of the invention, the pressure element is formed from a separating element, which allows for a very small and compact design of the compression device, and consequently, the filter cartridge design. Flow openings can be formed within the pressure element. Thus, pressure can be transmitted from the pressure element to the filter medium, and separation of the filter medium can also be achieved.

[0032] To achieve exceptionally simple installation of the filter cartridge, the compressor unit can be manufactured as a single piece. Only minimal assembly work is required to insert the single-piece compressor unit. Furthermore, the elimination of the need for pre-assembly of compressor units consisting of multiple individual components avoids the time-consuming and costly process of pre-assembly.

[0033] In another embodiment of the invention, the compression device is made of plastic. The compression device can be made as a single piece and can be designed so that it can be manufactured by a plastic injection molding process. Plastic parts can be manufactured cost-effectively by a plastic injection molding process, especially for mass production.

[0034] According to another embodiment of the invention, an intermediate layer is disposed between the separation element and the filter medium. The intermediate layer can be made of a non-woven or woven material. This non-woven or woven layer can retain small-sized particulate filter media so that it does not escape through the flow openings provided in the separation element. Simultaneously, the non-woven or woven layer is permeable to liquid, allowing filtered water to pass through. Thus, the formation of channels within the filter medium can be prevented without excessively interfering with the flow of liquid through the filter cartridge. Because such an intermediate layer can retain very small particles in the particulate filter medium, the flow openings can be designed to be very large in diameter and total cross-sectional area, which facilitates liquid flow. Therefore, a large volumetric flow rate of liquid can be achieved, which reduces the filtration time required for liquid filtration.

[0035] The intermediate layer can be inserted in a simple manner, for example, by loosely placing it between the separating element and the filter media in the filter cartridge. This makes it particularly easy to separate the filter cartridge components by type for recycling. To prevent undesirable displacement or shifting of the intermediate layer, the invention may optionally provide that the intermediate layer is connected to the separating element via ultrasonic welding or an adhesive process. The welded or adhesive connection can be designed so that, after the filter cartridge reaches the end of its service life, the non-woven layer can be easily removed from the separating element in a simple manner with virtually no residue. This facilitates the separation of the different components of the filter cartridge for subsequent recycling processes.

[0036] According to another embodiment of the invention, the intermediate layer may be composed of or contain filter media. As a result, the intermediate layer produces an additional filtration effect, which improves the filtration efficiency of the filter cartridge without significantly increasing its size. Furthermore, the additional filtration effect of the intermediate layer allows for a reduction in the total amount of filter media contained within the filter chamber area. Therefore, particularly small filter cartridges can be produced using a small amount of granular filter media.

[0037] To support the expansion motion, the intermediate layer can be made of an expansion medium, the volume of which increases due to contact with the liquid. This generates an additional compressive force acting on the filter medium. Therefore, the compression and spring mechanisms can be designed to be particularly small.

[0038] The intermediate layer can also be made of an elastic material that can be compressed in the event of filter media expansion. For some applications, the volume of the filter media may increase during the lifespan of the filter cartridge. An intermediate layer made of an elastic material can compensate for at least a small amount of expansion of the filter media.

[0039] According to a single state sample, which may also be combined with any feature of a filter cartridge according to the first state sample described above, the present invention provides a filter cartridge for filtering liquids, wherein the filter cartridge has a filter chamber housing having an inlet opening and an outlet opening for allowing liquid to flow through the filter chamber housing; wherein at least one filter medium for filtering the flowing liquid is disposed within a filter chamber volume surrounded by the filter chamber housing; and wherein the filter cartridge includes a compression device containing at least one compression element through which a compressive force can be applied to the filter medium to compress it; wherein the filter cartridge has two filter chamber zones that can be filled with particulate filter medium, and the compression device is disposed between the two filter chamber zones; wherein the compression device is designed such that the compression device can perform an expansion movement, and the compressive force is thus applied to the filter medium in each of the two filter chamber zones; and wherein the compression element is balloon-shaped.

[0040] The expansion movement can be achieved, for example, by a compression device that extends at least partially into the filter chamber housing and by a balloon-shaped compression element, whose volume increases as internal pressure is applied to the balloon-shaped compression element.

[0041] To allow liquid flowing through the filter chamber housing from one filter chamber section to another, the filter cartridge includes fluid channels for bypassing a compression device disposed between the two filter chamber sections. Such channels can be formed, for example, by pipes, along the inner wall of the filter chamber housing surrounding the balloon, providing fluid conduction between the two filter chamber sections, as the compression device is formed by a balloon. Each end of each pipe can be covered with a sieve to prevent the filter media from being carried through the pipes by the fluid. Alternatively, a toroidal balloon providing a channel through the open center of the toroidal balloon can also be used.

[0042] In one embodiment, the balloon-shaped compression element is a balloon made of an elastic and pressure-resistant material filled with compressed air.

[0043] The compressed air inside the balloon generates an outward force, causing the balloon to inflate and preventing the formation of cavities or channels in the filter material confined between two adjacent filter chambers. Simple Explanation of the Diagram

[0044] The invention will be more fully understood upon reference to the following detailed description and accompanying drawings, and further features will become apparent. The drawings are merely representative and are not intended to limit the scope of the claims. In fact, those skilled in the art will understand upon reading the following specification and reviewing the drawings that various modifications and variations can be made without departing from the innovative concept of the invention. The same components depicted in the drawings are denoted by the same reference numerals. Figure 1 illustrates a cross-sectional schematic diagram of a filter cartridge having a balloon-shaped compression device according to the present invention; Figure 2 illustrates a cross-sectional schematic diagram of another embodiment of the filter cartridge according to the present invention; Figure 3 illustrates a cross-sectional schematic diagram of another embodiment of the filter cartridge according to the present invention; and Figure 4 illustrates a perspective view of the compression device of the filter cartridge according to the present invention. Implementation

[0045] Figure 1 illustrates a filter cartridge 1 according to the present invention, in which a compression device 2 is disposed. The filter cartridge 1 and the filter chamber housing 3 of the filter cartridge 1 are designed to be cylindrical and elongated. Two granular filter media 4 are disposed within a filter chamber volume 5 surrounded by the filter chamber housing 3. The filter chamber housing 3 has two filter chamber areas 6, in which the filter media 4 is disposed. Liquid flowing into the filter cartridge 1 through the inlet opening 7 is filtered by the filter media 4 and flows out of the filter cartridge 1 through the outlet opening 8.

[0046] A compression device 2 is disposed between two filter chamber zones 6. The compression element 9 of the compression device 2 is a balloon containing compressed air. By applying internal pressure to the balloon-shaped compression element 9, the balloon attempts to increase its volume and inflate. The compression device 2 also includes two pressure elements 10, each formed by a pressure plate. The two pressure elements 10 are disposed on opposite sides of the compression element 9, i.e., for each filter chamber zone 6, the corresponding pressure plate of the compression device 2 faces its respective filter chamber zone 6. Both pressure elements 10 can be pushed in the direction of the filter medium 4 contained within their respective filter chamber zones 6. If the compression device 2 produces an expansion movement, each pressure element 10 displaces in the direction of its corresponding filter chamber zone 6 and applies a compressive force to the filter medium 4 contained therein. The pressure acting on the filter medium 4 compresses the filter medium 4, thereby preventing the formation of unwanted channels within the filter medium 4 due to liquid flowing through it.

[0047] One or more pipes 11 are arranged along the inner wall of the filter chamber housing 3, which surrounds the balloon-shaped compression element 9. The pipes 11 provide fluid conduction connections between two filter chamber areas 6 on opposite sides of the compression element 9.

[0048] The compression device 2, especially the compression element 9, allows for flexible compensation of volume changes of the filter media in one or both filter chamber zones 6.

[0049] Figure 2 illustrates a preferred embodiment of the filter cartridge 1 according to the invention. The compression device 2 has a spring device 12 mounted between two pressure plates of the pressure element 10. The spring force generated by the spring device 12 attempts to move each pressure element 10 into the corresponding filter chamber region 6, resulting in a compressive force acting on the filter medium 4 contained in each filter chamber region 6. The spring pressure can be generated in a particularly simple form through the spring device 12. The spring device 12 includes a plurality of spring elements 13 designed as compression springs. In Figure 2, the spring elements 13 are illustrated as being in a compressed state, wherein the spring device 12 generates a compressive force in the direction of the two filter chamber regions 6. Between each pressure element 10 and the closed inner wall of the filter chamber housing 3, a thin film 14 is configured in a liquid-sealed manner. The thin film 14 is made of an elastic material. During the expansion movement of the compression device 2, the pressure element 10 presses against the elastically deformed thin film 14 under force, thus applying a compressive force to the filter medium 4. The pressure acting on the filter medium 4 compresses the filter medium 4, thus preventing the formation of channels within the filter medium 4.

[0050] The compression device 2 forms a separation device 15 with separation elements 16, whereby the separation elements 16 are formed by the respective pressure plates of the corresponding pressure elements 10. Each separation element 16 includes a plurality of flow openings 17 through which the fluid to be filtered can pass. The diameter or cross-sectional area of ​​the flow openings 17 is preset such that particles of the granular filter media 4 cannot pass through the flow openings 17. This separates the two filter media 4 from each other. The two filter media 4 can be made of different filter materials. Thus, one filter media 4 may contain activated carbon material, while the other filter media 4 may contain ion exchange resin or other materials, such as those affecting the hardness of the water in the filter cartridge.

[0051] Figure 3 illustrates another embodiment of the filter cartridge 1 according to the invention. On each side of the compression device 2, an intermediate layer 18 is inserted between the separation element 16 and the filter medium 4. The intermediate layer 18 is made of a non-woven fabric layer. This non-woven material retains the particulate filter medium 4, preventing it from escaping through the flow opening 17 provided in the separation element 16. The intermediate layer 18 may be made of or contain filter material, thereby achieving additional filtration effects. This allows for very efficient filtration of liquids within the small volume of the filter cartridge 1.

[0052] Figure 4 illustrates a preferred embodiment of the compression device 2 according to the invention. The spring device 12 has a plurality of spring elements 13 connected to each other via elastically deformable connecting portions. The spring elements 13 are of the coil spring type. The plurality of spring elements 13 are arranged in series and in parallel, which allows for easy modification and preset of desired spring travel and spring force. The compression device 2 includes two pressure plates located on opposite sides of the spring device 12. The pressure plates are designed as separating elements 16 and include flow openings 17 to provide fluid conduction connection between the two filter chamber zones 6. Additional components, such as inserts, plates, sealing elements, or fluid-permeable material layers, such as woven or non-woven materials, may be disposed outside or inside the spring-type compression device 2 to provide more effective separation and individual compression of the filter media 4, and to provide fluid conduction connection between the two filter chamber zones 6 within the filter chamber housing 3 on both sides of the compression device 2.

[0053] The pressure element 10 applies compression force to the filter medium 4 and also separates or retains the filter medium 4. The compression device 2 illustrated in Figure 4 can be made of metal, plastic or composite material, or it can be manufactured as a single component, for example, made of suitable metal or plastic material.

[0054] In addition, the compression device 2 also allows for compensation for volume changes of the filter medium 4 that may occur during the service life of the filter cartridge 1, for example, due to chemical or mechanical changes of the filter medium 4.

[0055] 1: Filter Cartridge 2: Compression device 3: Filter chamber housing 4: Filter media 5: Filter chamber volume 6: Filtration Chamber Area 7: Entrance opening 8: Exit opening 9: Compression element 10: Pressure Components 11: Pipeline 12: Spring device 13: Spring element 14:Thin film 15: Separation device 16: Separating element 17: Flow opening 18: Intermediate Layer

Claims

1. A filter cartridge (1) for filtering liquid, wherein the filter cartridge (1) has a filter chamber housing (3) having an inlet opening (7) and an outlet opening (8) for allowing liquid to flow through the filter chamber housing (3); wherein at least one filter medium (4) for filtering the flowing liquid is disposed within a filter chamber volume (5) surrounded by the filter chamber housing (3); wherein the filter cartridge (1) includes a compression device (2) containing at least one compression element (9), through which a compression force can be applied to the filter medium (4) to compress the filter medium (4); wherein the filter cartridge (1) has two filter chamber regions (6), each filter chamber region being filled with a granular filter medium (4), and the compression device (2) is disposed between the two filter chamber regions; The compression device (2) forms a separation device (15) through which the two filter media (4) in the two filter chamber regions (6) are separated from each other, the separation device (15) allowing a fluid connection between the filter chamber regions (6) or being bypassed by a fluid connection; and wherein the compression device (2) is designed such that the compression device (2) can perform an expansion movement and a compressive force is thus applied to the filter media (4) in each of the two filter chamber regions (6), characterized in that at least one compression element (9) is disposed between two pressure elements (10), each of the two pressure elements being pressed into its respective filter chamber region (6) by the expansion movement, and the separation device (15) includes two separation elements (16) formed by the respective pressure elements of the pressure elements (10). An intermediate layer (18) is provided between the two separating elements (16) and the filter medium (4), wherein the intermediate layer (18) is made of an expanding medium whose volume increases when in contact with a liquid or of an elastic material that can be compressed when the filter medium (4) expands.

2. The filter cartridge of claim 1, wherein the pressure element (10) can move like a piston into the interior of the respective filter chamber area (6).

3. The filter cartridge of claim 1 or 2, wherein the compression device (2) is configured to contract as the volume of the filter medium (4) increases during the service life of the filter cartridge.

4. The filter cartridge of claim 1, wherein the compression device (2) is completely surrounded by the filter chamber housing (3).

5. The filter cartridge of claim 1, wherein the compression device (2) is at least partially made of an elastically deformable material.

6. The filter cartridge of claim 1, wherein the pressure element (10) is made of a non-elastic material.

7. The filter cartridge of claim 1, wherein the at least one compression element (9) includes a spring device (12), and wherein the pressure element (10) is pressed into a filter chamber region (6) through the spring device (12) to generate a compressive force acting on the filter medium (4).

8. The filter cartridge of claim 7, wherein the spring device (12) includes one or more spring elements (13).

9. The filter cartridge as requested in item 7 or 8, wherein the spring device (12) is disposed between the two separating elements (16) such that the two separating elements (16) are each pressed outward relative to each other.

10. The filter cartridge of claim 9, wherein the separating element (16) includes one or more flow openings (17) through which liquid can pass.

11. As in request item 1, the filter box, wherein, The compression device (2) is made as a single piece; and / or the compression device (2) is made of plastic.

12. The filter cartridge of claim 1, wherein the intermediate layer (18) contains filter material to retain particles of the granular filter medium (4).

13. The filter cartridge of claim 1, wherein the compression element (9) is balloon-shaped; preferably, the balloon-shaped compression element (9) is a balloon made of an elastic and pressure-resistant material filled with compressed air.

14. The filter cartridge of claim 1, wherein the compression device (2) is loosely disposed between two filter chamber areas (6) within the filter chamber housing (3).

15. The filter cartridge of claim 1 is provided with one or more bypass pipes separate from the compression device (2), or is provided in the compression device (2) with a plurality of openings that allow fluid to flow freely through the compression device (2).

16. The filter cartridge of claim 1, wherein one surface of the pressure element (10) is smaller than the cross-sectional area inside the filter chamber region (6), and a deformable membrane is installed in a liquid-tight manner between the outer edge of the pressure element (10) and the inner wall of the filter chamber housing (3) surrounding the pressure element (10).

17. The filter cartridge of claim 1, wherein a thin film (14) completely covering the internal cross-sectional area of ​​the filter chamber housing (3) is disposed in the filter chamber area (6), the pressure element (10) presses against the thin film (14) and the pressure element (10) applies pressure through the thin film.

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