FILTER WITH CENTERING

Description

[0001] The invention relates to a filter cartridge according to the preamble of claim 1.

[0002] Filter cartridges are regularly used in water-using household appliances with a water tank, especially in beverage machines such as coffee machines, tea makers, etc., to improve water quality according to the intended application. Such filter cartridges often contain filter media for water softening, such as ion exchange resin, or for flavor enhancement, such as activated carbon. The metered addition of additives, e.g., for health or flavor enhancement, such as the addition of minerals or vitamins, is also already provided for in combination with filter media.

[0003] State-of-the-art water tanks of such machines regularly have connection structures on the tank bottom with an annular sealing surface for the tight connection of a connection element of the filter cartridge provided for such a tank, which enclose a flow opening in the tank bottom for the flow of water from the filter cartridge and the water tank to the household appliance.

[0004] Such water tanks and filter cartridges are described, for example, in the documents DE 10 2204 049 877 A1, EP 1 867 606 A1 and DE 197 17 054 C2.

[0005] These publications describe how the filter cartridge can be fixed to the tank bottom in different ways, e.g. with a snap-on seal, a bayonet lock or a screw cap.

[0006] Screw and bayonet closures have the disadvantage that they superimpose a rotary movement with a linear movement when making the connection, which is difficult to achieve in tightly shaped water tanks and also requires correspondingly resilient, elastic seals.

[0007] Although a snap-on rim allows the filter cartridge to be inserted easily in a linear insertion movement, it is associated with limitations regarding the shape of the sealing surface.

[0008] In the prior art, EP 2 138 078 A1 discloses a water tank and a non-destructively removable filter cartridge connection element that can be connected thereto.

[0009] US 2010 / 0025317 A1 discloses a filter device with a replaceable filter cartridge and a toothed coding structure.

[0010] US 2006 / 054547 A discloses an oil filter with a toothed coding structure.

[0011] And WO 2008 / 017492 A discloses a water tank and filter cartridges that can be used therein with different coding structures, such as polygon, bayonet, and toothing.

[0012] The object of the invention is therefore to propose such a filter cartridge and an associated water tank without the aforementioned disadvantages.

[0013] This object is achieved by a filter cartridge according to the preamble of claim 1 and by a water tank according to the features of the preamble of claim 15, respectively, by their characterizing features. Advantageous and expedient developments are specified in the dependent claims.

[0014] In the following, elements generally associated with the water tank are designated with the initial word "tank," and elements associated with the filter cartridge are designated with the initial word "filter." Features of advantageous embodiments and further developments of the invention are described below in such a way that they are not mandatory, but may be present.

[0015] The filter cartridge according to the invention is provided with a filter housing whose wall separates a housing interior from a housing exterior in a watertight manner. A filter inlet opening is provided at the lower end of the filter cartridge in its operating position and is open to the outside environment of the filter housing. This distinguishes the filter cartridge from filter devices whose housings are tightly connected to water pipes of a water network with pressure-resistant connections and thus integrated into the water network.

[0016] Furthermore, a filter cartridge according to the invention comprises, in relation to the flow direction during operation, a device for conducting water inside the filter housing, adjacent to the filter inlet opening. This device comprises at least one filter chamber containing at least one filter medium and ends in a filter outlet opening for extracting water from the filter cartridge. Furthermore, an annular filter connection is provided for connecting the filter cartridge to a water tank.

[0017] Starting from such a filter cartridge and such a water tank according to the preamble of claims 1 and 11, the above-mentioned object is achieved by their characterizing features.

[0018] Accordingly, in a filter cartridge according to the invention, a filter-side guide structure is provided within the filter sealing surface of the filter connection to accommodate a tank-side centering element for securing the filter cartridge. Positioning and securing are thus easily accomplished by a centering element protruding from the tank bottom. Since the sealing surface itself can be designed independently of such a centering element, greater design freedom exists both in the design of the sealing surface or seal and the centering element.

[0019] A filter-side guide structure for accommodating the centering element when inserting the filter cartridge into the water tank can, for example, form a section of the filter cartridge's outlet line, which is located downstream of the end of the filter section in terms of flow during operation. This dual function of the filter-side guide structure, which serves not only to secure the filter cartridge but also to guide the water, results in a space-saving design.

[0020] Between the section of the outlet line having the guide structure and the end of the filter section, a further section of the outlet line, hereinafter referred to as the inner section, can be provided, which connects the section of the outlet line having the guide structure to the filter section. The section of the outlet line having the guide structure can have a larger cross-section than an inner section of the outlet line located upstream of it.

[0021] A connection piece with the filter sealing surface, which is located downstream of the guide structure in relation to the flow during operation, can in turn have a larger cross-section than the guide structure and comprise an outlet section of the outlet line. The guide structure then represents a transition section of the outlet line between the inner section and the outlet section.

[0022] In special embodiments, the filter-side guide structure has one or more transition surfaces arranged diagonally relative to the mounting direction of the filter cartridge in the transition section. Such diagonally arranged transition surfaces are suitable for facilitating the positioning of the filter cartridge during assembly by accommodating a tank-side centering element.

[0023] The aforementioned sections of the outlet line are preferably arranged coaxially with a central axis (A) of the outlet line. The one or more inclined transition surfaces can connect the transition section to the inner section of the outlet line in a radially outer-to-inner direction and axially from bottom to top relative to the operating position of the filter cartridge.

[0024] Preferably, the transition surfaces form a stop surface so that the guide structure can abut against a correspondingly designed tank-side centering element with one or more inclined guide surfaces when plugged into the final position.

[0025] The filter-side guide structure can be designed and arranged coaxially with a filter sealing surface surrounding the guide structure. This central arrangement enables the even distribution of the open flow cross-section for the water through the filter-side guide structure.

[0026] The filter-side guide structure may further comprise one or more guides running parallel to a central axis A.

[0027] As already mentioned, the tank-side centering element preferably has one or more inclined guide surfaces. A filter cartridge can initially be centered on the inclined guide surface(s) of the tank-side centering element when the guide structure is attached to a tank-side centering element. It can then be further axially displaced centrally using the axially parallel guide surface(s), for example, to create a sealing and / or securing positive connection with a sealing and / or securing surface. Depending on the design, one or more tank-side guide surfaces may or may not come into contact with one or more filter-side transition surfaces.

[0028] Advantageously, retaining or locking elements are also mounted in the filter-side guide structure. This allows for designs that are fully or partially held internally, eliminating or at least reducing the need for external fixing devices.

[0029] The outlet section of the outlet line advantageously has a larger cross-section than the transition section of the outlet line comprising the guide structure. The transition section can be connected to the outlet section by a connecting wall extending transversely to the central axis (A). This connecting wall can further comprise axial recesses and / or axial projections.

[0030] In this connecting wall, the axial recesses and / or axial projections can be arranged in the area of ​​radial bulges of the filter sealing surface.

[0031] By angularly aligning the guide structure, e.g., by angularly aligning guide grooves or guide edges of the guide structure, relative to these axial recesses and / or projections, a mechanical coding or key / lock function can be created to ensure that only a filter cartridge suitable for the respective application can be used.

[0032] In addition, the axial recesses and / or axial projections may have an elongated shape with an angular orientation relative to a radius extending from the central axis, whereby this angular orientation may also have an additional function.

[0033] For example, the axial recesses and / or axial projections can form elements for additional coding of the filter cartridge due to their position and / or angular orientation.

[0034] Advantageously, the filter-side guide structure also includes a receptacle for a plug-in element of a tank valve, which extends through the tank-side centering element. Such a plug-in element must be movably accommodated in the guide structure of the filter cartridge and must not be fixed during assembly of the filter cartridge, as otherwise the tank valve will not function. Such a plug-in element thus represents additional coding to prevent the use of an unsuitable filter cartridge.

[0035] Furthermore, it is advantageous if the tank-side centering element and the tank valve are adapted to each other in such a way that the tank valve is coded with the centering element. A tank with a tank valve designed in this way can therefore only be operated in conjunction with a matching centering element. In a special embodiment of the invention, the plug-in element of the tank valve engages a passage of the centering element.

[0036] The guide structure of the filter cartridge can have one or more guide grooves for accommodating tank-side structures. This creates a tongue-and-groove structure for filter centering and fixation, thus also fixing the angular position of the filter cartridge. This also opens up additional coding options.

[0037] The one or more inclined transition surfaces of the filter-side guide structure can be mounted in one or more guide grooves for receiving tank-side structures.

[0038] A water tank for a household appliance that fits a filter cartridge described above is provided with a tank base, as mentioned in the introduction. An annular tank sealing surface is provided on the tank base for tightly connecting the filter cartridge. This sealing surface encloses a tank passage opening for the flow of water from the filter cartridge through the wall of the tank base to the household appliance. Furthermore, a centering element protruding from the tank base in the direction of the filter cartridge mounting position is provided within the tank sealing surface for insertion into the guide structure of the filter cartridge.

[0039] At least one water passage for water from the filter cartridge through the guide structure of an attached filter cartridge to the tank passage opening can be provided on the centering element. This allows the centering element to at least partially rest against the inner wall of the filter-side guide structure without impeding the water flow.

[0040] The tank sealing surface is advantageously designed and arranged separately from the centering element, whereby these two elements can be designed largely independently of each other and do not influence each other.

[0041] One possibility for providing one or more flow openings for the water is, for example, for the centering element to comprise ribs extending in the direction of water flow during operation, the space between which forms a water passage. The ribs can then act as guide ribs, abutting the filter-side guide structure in a radial direction.

[0042] The centering element can, for example, have a centering base from which the guide ribs can extend upwards relative to the operating position of the water tank and which has an outer surface on the outside circumference, which can possibly also form a tank sealing surface.

[0043] Axial projections and / or axial recesses can be provided in the centering base in order to insert or fit the axial recesses and / or axial projections of the filter cartridge.

[0044] The axial projections and / or axial recesses on the centering base can be conveniently arranged in the region of the radial bulges of the outer surface of the centering base.

[0045] By angularly aligning these axial projections and / or axial recesses on the centering base relative to the centering element, in particular relative to the centering base or ribs attached thereto, the coding or key / lock function suitable for a guide structure with corresponding axial recesses and / or axial projections can be created. This angular relationship can be permanently established during the formation of the respective axial projections and / or axial recesses, or it can be provided in an adjustable manner via one or more adjustable additional elements supporting the respective axial projections and / or axial recesses.

[0046] The axial projections and / or axial recesses on the centering base may also have an elongated shape with an angular orientation relative to a radius emanating from the central axis, whereby this angular orientation may have an additional function.

[0047] For example, the axial recesses and / or axial projections of the centering element can form elements for additional coding with the guide structure of the filter cartridge by means of a position and / or angular alignment that matches the guide structure of the filter cartridge.

[0048] If the centering element is designed with ribs arranged in a star shape, this results in a uniform distribution of the open flow cross-section for the water and, at the same time, a uniform circumferential arrangement and thus fixation of the filter-side guide structure of the filter cartridge.

[0049] At least one, preferably several or all, ribs of the centering element are provided with an upper inclined guide surface for guiding the filter-side guide structure during assembly of the filter cartridge. This inclined guide surface or inclined guide surfaces can then interact with the corresponding inclined transition surface(s) of the guide structure of the filter cartridge. In addition, at least one guide surface of the centering element running parallel to the central axis can be provided for axially aligned guidance of the filter cartridge after centering during further insertion and / or insertion.

[0050] Furthermore, holding or locking elements can be attached to the centering element, which are adapted to corresponding holding or locking elements of the guide structure of the filter cartridge.

[0051] It is also advantageous if the centering element is attached to a mounting ring for attachment to the tank base. This allows different mounting rings with specific centering elements to be used for similarly designed water tanks, which can then be specified for different household appliances such as beverage machines, etc.

[0052] An embodiment of the invention is shown in the drawing and is explained in more detail below with reference to the figures.

[0053] Show in detail Fig.1 a perspective view of a tank bottom with inserted filter cartridge according to the state of the art, Fig.2 a perspective exploded view of a tank bottom with centering element and fastening ring, Fig.3 a perspective view of the tank bottom according to Fig. 2 with built-in centering element and built-in mounting ring, Fig.4 a plan view of the tank bottom according to the Figuren 2 and 3 , Fig.5 a perspective view of the connection area of ​​the filter cartridge viewed from the side, Fig.6 a perspective view of the connection area of ​​the filter cartridge viewed diagonally from below, Fig.7 a perspective view of a filter cartridge cut open at the level of the filter connection nozzle, inserted into a tank bottom, Fig.8 a perspective view of a filter cartridge cut open at the level of the guide grooves, inserted into a tank bottom, Fig. 9 a perspective view of a filter cartridge inserted into a tank bottom, Fig. 10 a perspective view of the centering element, Fig. 11 a sectional view of a tank bottom without a filter cartridge with the water tank valve open, Fig. 11a and b two enlarged sections Fig. 11 to illustrate a closable bypass line in the tank seal, Fig. 12 a sectional view of a tank bottom according to Fig. 11 with inserted filter cartridge, Fig. 12a a detail enlargement Fig. 12 to illustrate the closed bypass line, Fig. 13 a schematic front view of a filter connection piece according to the invention, Fig. 13a a detail enlargement Fig. 13 , Fig. 14 a section of the filter cartridge showing the connection area to illustrate a guide aid through bevels of the connection piece, Fig. 15 a perspective view of the centering element with additional axial projections on the centering base and Fig. 16 a perspective view of a matching filter cartridge with guide structure.

[0054] Fig. 1 illustrates the usual design of a water tank 1 of a beverage machine, such as a coffee machine, e.g., a fully automatic coffee machine, according to the prior art. The water tank 1 comprises a tank base 2 and water tank side walls 3, partially shown by dashed lines. A filter cartridge 4 with a filter housing 5 is inserted into the water tank 1. The connection between the tank base 2 and the filter cartridge 4 is realized via tank connection elements 6 on the water tank side and filter connection elements 7 on the filter side.

[0055] The filter cartridge 4 is located in the interior 8 of the water tank 1, i.e., during operation, it is completely or partially immersed in the water stored in the water tank 1. A filter connection piece 9 of the water tank 1 for connecting the water tank 1 to the beverage machine (not shown) protrudes from the underside of the water tank 1.

[0056] In Fig. 2 a round section of the tank bottom 2 is shown, wherein a fastening ring 10 and a centering element 11 are provided for insertion into a recess 12 of the tank bottom 2. A tank valve body 13 with a seal 14 designed as an O-ring, from which two pins 15 protrude upwards, is also shown in Fig. 2 The fastening ring 10 also carries an elastomer seal 16.

[0057] In the Fig. 3 und 4 The fastening ring 10 and the centering element 11 are installed in the tank base 2. Here, it can be seen that the pins 15 can penetrate the centering element and thus form coding elements for the coding of the water tank relative to the associated machine connection, from which the tank valve body 13 must be actuated when inserting the water tank. Furthermore, Fig.4 It is clearly visible that the elastomer seal 16 forming the water tank seal 17 is an annular seal having a varying radius R along its circumference relative to a central axis A, so that the inner surface of the water tank seal 17 forming a tank sealing surface 18 comprises radial indentations 19 and radial protrusions 20. The first tank sealing surface 18 also serves as the first tank fixing surface.

[0058] In Fig. 5 The connection area 21 of a matching filter cartridge 22 is shown. A filter connection piece 23 forms an inner ring which is surrounded by an outer ring 24 with axially extending projections 25 and recesses 26. Between the inner ring 23 and the outer ring 24 is an annular inlet screen 27 through which water enters the filter cartridge. The outer surface 28 and the inner surface 68 of the filter connection piece 23 are also provided with bulges 29 and indentations 30 to match the tank sealing surface 18. The outer surface 28 and / or the inner surface 68 of the filter connection piece 23 can also serve as a filter fixing surface.

[0059] In the view of Fig. 6 In addition to the above-described parts of the connection area 21 of the filter cartridge 22, the special design of a guide structure 31 of the filter cartridge 22 for receiving the centering element 11 is shown. The guide structure has guide grooves 32, which are aligned with the edges 33 of a polygonal ring 34, in this case, for example, with six guide grooves aligned with six edges of a hexagonal ring. In the sectional view looking from above to Fig. 7 the cutting plane passes through this polygon ring 34.

[0060] Towards the top of the interior of the filter cartridge, inner curvatures 35 are located between the edges 33 and the guide grooves 32. The inner curvatures 35 form the lateral walls 36 of the guide grooves 32. Due to this curved shape, the walls 36 of the guide grooves 32 taper both in the axial direction upwards (relative to the operating position) and in the radial direction from the inside to the outside. In the interface, viewed from above according to Fig. 8 The cutting plane runs at a height where the guide grooves 32 are clearly visible. A riser pipe 37 is located centrally inside, through which the water entering the filter cartridge 22 is directed upwards to the filter section.

[0061] In Fig. 9 The entire filter cartridge 22 is shown in a filter housing 37, which has an optional lateral metering opening 38 and the described bottom-side water connection. The optional metering opening 38 is only provided in the case of a filter cartridge design that is designed for the release of additives, e.g., minerals, vitamins, or the like, from a metering chamber accommodated in the filter housing 37 into the water supply. Since such a metering chamber within the filter housing 37 is closed off from the filter section, it has no further significance with regard to filtration. A filter cartridge according to the invention can therefore easily be designed without this metering chamber and its metering opening 38. Fig. 9 In particular, the operating position to which the information above and below in this description refers is recognizable.

[0062] In Fig. 10 A perspective view of the centering element 11 can be seen. The centering element is provided with a base plate 39 which, when mounted, engages behind the edge of the elastomer seal in a receptacle. A centering base 40 protrudes upward from the base plate 39 and has an annular outer surface 41, which also forms a second tank fixing surface. This outer surface 41 has a radius that varies along the circumference relative to the central axis A, so that this outer surface 41 also includes radial indentations 42 and protrusions 43. The outer surface 41 is thus adapted to a corresponding shape of the filter connection piece 9.

[0063] For further adaptation, the indentations 42 and protrusions 43 of this outer surface 41 are also designed to oscillate periodically around a circular line and have a rounded shape. In the illustrated embodiment, corresponding to the design of the illustrated embodiment of the filter cartridge 22, six indentations 42 and six protrusions 43 are provided along a circular line with a diameter of less than 3 cm. For a different filter cartridge, the adaptation of the outer surface 41 or the second tank fixing surface must be modified accordingly.

[0064] All adjustments to the outer surface 41 of the centering base 11 result in only an annular slot between the outer surface 41 and the elastomer seal 16 being open for the insertion of the filter connection piece 23 when installed. This provides further protection against the use of an unsuitable filter cartridge. Furthermore, this allows the filter connection piece 23 to be supported on its inner side against the outer surface 41 of the centering base 11. This allows the contact pressure of the filter connection piece on the elastomer seal 16 to be increased evenly along the entire circumferential shape by varying the shape.

[0065] Above the annular outer surface, at least one upwardly projecting tooth 44 is provided. The one or more teeth 44 are mounted on a step 45 of the centering base 40. Further elevations 46, following the shape of the outer surface 41, opposite the step 45 are mounted at a distance from the teeth 44 such that a gap 47 remains between the teeth and the elevations 46. The tooth or teeth 44 and / or the elevations 46 can prevent the use of an axial seal to circumvent the coding. Furthermore, a passage opening 48 is provided above the outer surface 41, which, when the centering element 11 is mounted, leads to a tank passage opening. The filtered water from a filter cartridge 22 can be drained from the water tank through this passage opening 48.

[0066] One or more bottom openings 49 are provided below the outer surface 41 in the base plate 39. Unfiltered water from the water tank can be directed through these bottom openings. Below the raised portions 46 and within the wall supporting the outer surface 41, a cavity 50 is formed for accommodating the tank valve body 13.

[0067] Above the annular outer surface 41, guide ribs 51 are provided, which may be beveled on their upper side as in the illustrated embodiment. The thus formed beveled guide surfaces 52 assist in the insertion of the guide ribs 51 into the guide grooves 32 of a filter cartridge 22. In the sectional view according to Fig. 4 the inclined guide surfaces 52 of the guide ribs 51 in the attached filter cartridge 22 can be clearly seen.

[0068] In the Fig. 11 , 11a , 11b , 12 and 12aThe assembled components of the water tank 1 are shown for connecting a filter cartridge with and without a filter cartridge 22. The fastening ring 10 is provided with a locking projection 53, with which it can lock onto the tank bottom 2 by engaging behind a bottom rib 54 of the water tank. The elastomer seal 16 has a bottom section 55 that engages under the fastening ring 10 and thus holds the elastomer seal 16 with the fastening ring 10 to the tank bottom 2.

[0069] To seal against the tank bottom 2, the elastomer seal 16 has a sealing surface, which in this case is implemented by a sealing bead 56. To ensure a tight seal between the elastomer seal 16 and the fastening ring 10, a circumferential sealing surface can be provided at various locations. In the illustrated embodiment, an annular seal 57 is provided, which is molded onto the top of the elastomer seal 16 and seals with the fastening ring in a sealing groove 58 of the fastening ring.

[0070] The elastomer seal 16 comprises an outer ring 59 and an inner ring 60, which are formed and connected to one another in one piece. The outer ring 59 and the inner ring 60 both follow in their shape along the circumference the varying radius of the fastening ring 10, the filter connection piece 23 and the elastomer seal 16 and the indentations and bulges formed thereby. The outer ring 59 is stepped and carries the annular seal 57 and the sealing bead 56. The outer ring 59 is further provided with one or more bypass openings 61 through which unfiltered water can reach the annular gap 62 between the outer ring 59 and the inner ring 60 in the flow direction P1. The bypass opening 61 of the elastomer seal 16, in the assembled state, is located directly adjacent to a bypass opening 63 in the fastening ring 11, which, for example, can also be found in the Fig. 1 and 3can be seen. Unfiltered water from the annular gap 62 in the water tank 1 can flow through the bypass opening 63 in the direction of P2 into the corresponding beverage machine.

[0071] The inner ring 60 has a sealing lip 64 on its underside, which is opposite a sealing surface 65 on the outer ring 59. In the relaxed state of the elastomer seal 16, the annular gap 62 between the outer ring 59 and the inner ring 60 is open at the bottom, as shown in Fig. 11 can be seen, so that the unfiltered water guided in the bypass can flow out of the annular gap 62 in the flow direction P2. In this state, the inner side 66 of the inner ring 60, which forms the water tank seal 17, is beveled inwards in its downward direction. The design of the bypass is shown in the enlargements according to the Fig. 11a and b highlighted.

[0072] When inserting a filter cartridge 22 with the filter connection piece 23, the elastomer seal 16 is deformed so that the inner side 66 is pressed outward and runs essentially vertically along the filter connection piece. In doing so, the sealing lip 64 is pressed onto the opposite sealing surface 65, thus closing the annular gap 62 and thus also the bypass through the bypass openings 61, 63. The deformation generates a contact pressure that presses the tank sealing surface 17 against the filter sealing surface 28 and simultaneously presses the sealing lip 64 onto the sealing surface 65. This state is Fig. 12 and Fig. 12a shown.

[0073] The tank valve body 13 is in both Fig. 11 as well as in Fig. 12 By means of a stop (not shown in detail) of the associated machine, it is lifted into the cavity 50 against a return spring 67, thus remaining in the open position corresponding to the inserted water tank. If the water tank is removed from the machine, the tank valve body 13 closes under the pressure of the return spring 67.

[0074] The tank sealing surface 18 is formed by the inner side 66 of the elastomer seal 16 and at the same time represents a first tank fixing surface 18. As already mentioned above, a first filter fixing surface 28 formed by the filter sealing surface 28 rests on this side in the inserted state of the filter cartridge 5, 22 under a contact pressure which deforms the elastomer seal 16 in such a way that a fixing and sealing form fit is achieved.

[0075] On the outer surface 41 forming the second tank fixing surface there is a second filter fixing surface 68 (see Fig. 5 ) which is formed by the inner surface of the filter connection piece 23. This positive connection is also created under contact pressure. Due to the inventive shape of the filter connection piece 23, it forms an annular wall 69 which can be elastically expanded if necessary. This results in the possibility of tolerance compensation with good fixing, which is brought about by the corresponding bracing. Due to the mutually parallel or mutually inclined shape of the first filter fixing surface 28 and a second filter fixing surface 68, the annular, corrugated wall 69 of the connection piece 23 lying between them forms a corrugated annular spring 70. The second filter fixing surface 68 can also act as a second filter sealing surface.

[0076] The filter connection piece according to the front view Fig. 13 and the detail enlargement according to Fig. 13a shows the described waveform with bulges 29 and indentations 30. The annular wall 69 of the filter connection piece 23, with a wall thickness W, has the first filter fixing surface 28 on the outer wall side 71 and the second filter fixing surface 68 on the inner wall side 72. The outer wall side 71 and the inner wall side 72 run parallel in the illustrated view, but are beveled towards each other in the axial direction, which will be explained further below. The waveform is therefore further illustrated by a dashed center line 73.

[0077] The center line 73 runs in a wave-like manner between an outer enveloping circle 74 whose radius has the largest value of the varying radius, and an inner enveloping circle 75 whose radius has the smallest radius of the varying radius of the waveform. The bulges 29 and indentations 30 of the center line 73 form wave crests in the form of convex circular segments 76 and wave troughs in the form of concave circular segments 77. In the embodiment shown, all circular segments 76, 77 have the same segment radius S. The centers 78, 79 of the circular segments 76, 77 lie within the inner enveloping circle 75 for the convex circular segments 76 and outside the outer enveloping circle 74 for the concave circular segments 77. The convex circular segments 76 and the concave circular segments 77 merge tangentially into one another and are evenly distributed over the circumference, resulting in a rotationally symmetrical shape.In the illustrated embodiment, six convex circle segments 76 and six concave circle segments 77 are provided, which are alternately spaced at an angular distance of 30°, ie the convex circle segments 76 are spaced from one another by an angle α of 60° and the concave circle segments 77 are spaced likewise.

[0078] By selecting the segment radius and the associated position of the corresponding center points 78, 79, the center line runs with a comparatively flat, wave-like curve around the center circle line 80. The center line 73 intersects the center circle line 80 at an obtuse angle β. As a result, the arc length of the protrusions 29 is significantly longer than the arc length of the indentations 30, whereby the angle γ subtended by the segment arc of the protrusions 29 is significantly larger than the angle δ subtended by the indentations 30. This shape improves the spring action of the filter connection piece 23.

[0079] For comparison, the drawing also shows circular segments 81 whose segment centers 82 lie directly on the center line 73. This course, which is not realized in this embodiment, has significantly smaller segment radii and a substantially perpendicular course to the center line 73.

[0080] A good spring effect has been demonstrated for radii and wall thicknesses where the radius of the inner enveloping circle 75 is between 5% and 15% of the radius of the outer enveloping circle 74 and the radius of the convex and / or concave circular segments is between 20% and 35% of the radius of the outer enveloping circle 74. The wall thickness W between the outer wall surface 71 and the inner wall surface 72, which runs parallel or inclined thereto (relative to the operating position), is preferably between 5% and 15% of the radius of the outer enveloping circle 74.

[0081] In the example shown, the outer enveloping circle 74 has a radius of approximately 11 mm, and the inner enveloping circle 75 has a radius of approximately 9.75 mm. The segment radius of the convex and concave circular segments is approximately 3.08 mm, and the wall thickness between the outer wall side 71 and the inner wall side 72, which runs parallel or inclined thereto, is approximately 0.9 mm.

[0082] In Fig. 14 It can be seen that the outer wall 71 and / or the inner wall 72 of the filter connection piece 23, which, depending on the embodiment, also form one or two filter sealing surfaces 28, are beveled relative to the vertical by the angles ω1 or ω2, so that they converge from top to bottom relative to the operating position of the filter cartridge 4, 22. This bevel or bevels by the angle(s) ω1 and / or ω2 form an insertion aid when inserting the connection piece 23 into the annular gap between the elastomer seal 16 and the outer surface 41 of the water tank 1.

[0083] Fig. 15 shows a centering element 11, which is fixed to the tank bottom 2 by a fastening ring 10. In this embodiment, the centering base 40 is provided with axial projections 85, which are arranged in an angle characterized angular relationship to the guide ribs 51. By rotating the arrangement of the axial projections 85 relative to the guide ribs 51, as indicated by the double arrow V, a coding for a key / lock function can be generated.

[0084] The axial projections are on the centering base 11 in the area of ​​the radial bulges 43 of the outer surface 41, where there is sufficient space on the centering base of this design.

[0085] The axial projections 85 have an elongated shape in the illustrated embodiment, so that by their angular orientation in the angle an additional function, for example a coding function, can be realized with respect to a radius R extending from the central axis A.

[0086] Fig. 16 shows the connecting piece 9 with the filter sealing surface 28 of a matching filter cartridge 4. The guide structure 31, like the previously described embodiment, has a polygonal ring 34, which, however, in this embodiment runs in the axial direction with flat side walls 86 without the inner curvatures 35 and the guide grooves 32 formed thereby. In this embodiment, the inclined transition surface 87, together with the side walls 86, forms a transition section 88 to an inner section 89 of an outlet line 90 of the filter cartridge 4 and connects this to a first section 88 of the outlet line 90 arranged upstream of this during operation.

[0087] The connecting piece 9 represents on the inside an outlet section 91 of the outlet line 90 and is connected via a connecting wall 92 to the transition section 88 or the polygon ring 34 of the guide structure 31.

[0088] Axial recesses 93 are provided in this connecting wall 91. The recesses 93 are in their angular position relative to the edges 33 of the polygon ring (see angle ) are adapted to the angular position of the projections 85 of the centering element relative to the guide ribs 51, thereby realizing the key / lock function. The recesses 93 have an elongated shape corresponding to the projections 85 and are angularly aligned (see angle ) is adapted to the angular orientation of the projections 85 of the centering element relative to the radius R extending from the axis A, whereby the additional coding function described is realized. List of reference symbols:

[0089] 1Water tank 2Tank base 3Water tank side wall 4Filter cartridge 5Filter housing 6Tank connection element 7Filter connection 8Interior 9Filter connection nozzle 10Fastening ring 11Centering element 12Recess 13Tank valve body 14Seal 15Pin 16Elastomer seal 17Water tank seal / ring seal 18Tank sealing surface 19Recess 20Bulge 21Connection area 22Filter cartridge 23Filter connection nozzle / inner ring 24Outer ring 25Protrusion 26Recess 27Inlet screen 28Filter sealing surface / outer surface 29Bulge 30Bulge 31Guide structure 32Guide groove 33Edge 34Polygon ring 35Inner curvature 36Wall 37Filter housing 38Dosing opening 39Base plate 40Centering base 41Outer surface 42Indentation 43Bulge 44Tooth 45Step 46Elevation 47Gap 48Passage opening 49Bottom passage opening 50Cavity 51Guide rib 52Inclined guide surface 53Locking projection 54Bottom rib 55Bottom section 56Sealing bead 57Ring seal 58Sealing groove 59Inner ring 60Outer ring 61Bypass opening 62Annular gap 63Bypass opening64Sealing lip 65Sealing surface 66Inside 67Return spring 68Second filter fixing surface / inner surface 69Wall 70Ring spring 71Outside wall 72Inside wall 73Center line 74Outer enveloping circle 75Inner enveloping circle 76Convex circle segment 77Concave circle segment 78Center point 79Center point 80Center circle line 81Circular segment 82Segment center point 83Turning point 84Tank passage opening 85Axial projection 86Side wall 87Sloped transition surface 88Transition section 89Inner section 90Outlet line 91Exit section 92Connecting wall 93Recess AAxis WWall thickness SSegment radius P1Flow direction P2Flow direction RRadius VTwist

Claims

1. Filter cartridge (4) for the use in the interior of a water tank of a domestic appliance such as a beverage machine, in particular coffee machine, etc., having a filter housing (5) of which the wall separates in a watertight manner a housing internal side from a housing external side, wherein a filter inlet opening (27) which in the operating position of the filter cartridge (4) is disposed on the lower end region of the latter and is open in relation to the external environment of the filter housing (5) is provided, wherein provided downstream of the filter inlet opening (27) in terms of the flow direction of water during operation, in the interior of the filter housing (5), is a device for water conduction which comprises at least one filter chamber having at least one filter medium and terminates in a filter outlet line for suctioning water from the filter cartridge (4); and wherein a filter connector (9) having an annular filter sealing face (28) for connecting the filter cartridge (4) in a water tank is provided, characterized in that provided within the filter sealing face (28) is a guide structure (31), disposed separately from this filter sealing face (28), for receiving a centering element (11) for centering the filter cartridge (4), wherein the filter-proximal guide structure (31) in the transition portion to an inner portion (89) of the outlet line (90) has one or a plurality of oblique transition faces (87) which are disposed obliquely in relation to the assembling direction of the filter cartridge (4).

2. Filter cartridge according to Claim 1, characterized in that the filter-proximal guide structure (31) forms a portion (88) of an outlet line (90) of the filter cartridge (4), which in terms of the flow direction during operation is disposed downstream at the end of the filter section.

3. Filter cartridge according to one of the preceding claims, characterized in that the portion (88) of the outlet line (90) that has the guide structure (31) has a larger cross section than an inner portion (89) of the outlet line (90) that lies upstream in terms of the flow direction during operation.

4. Filter cartridge according to one of the preceding claims characterized in that the filter connector (9) that has the filter sealing face comprises an exit portion (91) of the outlet line (90) of the filter cartridge (4), the portion (88) that has the guide structure (31) forms a transition portion (88) of the outlet line (90), and the exit portion (90) has a larger cross section than the transition portion (88).

5. Filter cartridge according to one of the preceding claims, characterized in that der inner portion (89) and the exit portion (91) of the outlet line are disposed so as to be coaxial with a central axis (A) of the outlet line, and the transition portion (88) by means of one or a plurality of transition faces (87) that run obliquely from the exit portion (91) to the inner portion (89) and radially from the outside to the inside and axially from top to bottom in terms of the operation position of the filter cartridge, connects the exit portion (91) to the inner portion (89).

6. Filter cartridge according to one of the preceding claims, characterized in that the filter-proximal guide structure (31) is configured and disposed so as to be coaxial with the filter sealing face (28).

7. Filter cartridge according to one of the preceding claims, characterized in that the filter-proximal guide structure (31) has one or a plurality of guide faces which run parallel to the central axis (A), and / or one or a plurality of transition faces (87) which are disposed obliquely thereto.

8. Filter cartridge according to one of the preceding claims, characterized in that holding or latching elements are affixed in the filter-proximal guide structure (31).

9. Filter cartridge according to one of the preceding claims, characterized in that the exit portion (91) of the outlet line (90) of the filter cartridge (4) by way of a connection wall (92) that runs transversely to the central axis (A) is connected to the transition portion (88), wherein the connection wall (92) has axial depressions (93) and / or axial projections.

10. Filter cartridge according to one of the preceding claims, characterized in that the axial depressions (93) and / or axial projections are disposed in the region of radial convexities (29) of the filter sealing face (28).

11. Filter cartridge according to one of the preceding claims, characterized in that the axial depressions (93) and / or axial projections have an elongate shape with an angular alignment in relation to a radius emanating from the central axis.

12. Filter cartridge according to one of the preceding claims, characterized in that the axial depressions (93) and / or axial projections as a result of their position and / or angular alignment for coding the filter cartridge (4) are in an angular relationship with the guide structure (31)13. Filter cartridge according to one of the preceding claims, characterized in that filter-proximal guide structure (31) has one or a plurality of guide grooves (32) for receiving tank-proximal structures.

14. Filter cartridge according to one of the preceding claims, characterized in that one or a plurality of oblique transition faces (87) of the filter-proximal guide structure (31) are disposed in one or a plurality of guide grooves (32) for receiving tank-proximal structures.

15. Water tank (1) for a domestic appliance having a filter cartridge (4) according to one of the preceding claims and a tank bottom (2), wherein an annular tank sealing face (18), which encloses a tank passage opening for the flow of water from the filter cartridge (4) through the wall of the tank bottom (2) to the domestic appliance, for tightly connecting the filter cartridge (4) is provided on the tank bottom (2), characterized in that a centering element (11), which within the tank sealing face (18) projects from the tank bottom in the direction of the assembled position of the filter cartridge (4), for plugging into the filter-proximal guide structure of the filter cartridge is provided, wherein a tank valve which has a plug element that is movable by a tank valve body (13) and is able to be inserted through a passage of the centering element (11) is provided.

16. Water tank according to one of the preceding claims, characterized in that the centering element (11) is provided with at least one water passage for water from the filter cartridge (4) through the filter-proximal guide structure (31) of an attached filter cartridge to the tank passage opening.

17. Water tank according to one of the preceding claims, characterized in that the tank sealing face (18) is configured and disposed separately from the centering element (11).

18. Water tank according to one of the preceding claims, characterized in that the centering element (11) comprises guide ribs (51) which extend in the flow direction of the water during operation, the intermediate space of said guide ribs (51) forming a water passage.

19. Water tank according to one of the preceding claims, characterized in that the centering element (11) has a centering plinth (40) as a plinth element from which the guide ribs (51) extend upward in terms of the operating position of the water tank.

20. Water tank according to one of the preceding claims, characterized in that axial projections (85) and / or axial depressions for attaching or inserting the axial depressions (93) and / or axial projections of the filter cartridge (4) are affixed to the centering plinth (40).

21. Water tank according to one of the preceding claims, characterized in that the axial projections (85) and / or axial depressions on the centering plinth (11) are disposed in the region of the radial convexities (43) of the external face (41).

22. Water tank according to one of the preceding claims, characterized in that the centering element (11) comprises ribs (51) disposed in a star-shaped manner.

23. Water tank according to one of the preceding claims, characterized in that at least one rib (51) has an upper oblique guide face (52) and / or at least one guide face running parallel to the central axis for guiding the filter-proximal guide structure (31) when assembling the filter cartridge.

24. Water tank according to one of the preceding claims, characterized in that at least one rib (51) has an upper oblique guide face (52) for interacting in a guiding manner with at least one oblique guide face of at least one guide groove (32) of the filter-proximal guide structure (31) when assembling the filter cartridge.

25. Water tank according to one of the preceding claims, characterized in that holding or latching elements are affixed to the centering element (11).

26. Water tank according to one of the preceding claims, characterized in that the centering element (11) is affixed to a fastening ring (10) for the tank bottom (2).