EP4313353A1

EP4313353A1 - Water tank having a filter cartridge

Info

Publication number: EP4313353A1
Application number: EP22718081.7A
Authority: EP
Inventors: Kurt Wallerstorfer
Original assignee: Aclaris Water Innovations GmbH
Current assignee: Aclaris Water Innovations GmbH
Priority date: 2021-03-22
Filing date: 2022-03-21
Publication date: 2024-02-07
Also published as: WO2022200282A1; KR20230160858A; CN116472094A; CN116456871A; DE102022106568A1; AU2022245948A1; AU2022241914A1; DE102022106508A1; EP4312681A1; CN116490254A; CN117396113A; KR20230161467A; CN117440856A; CN116472251A; WO2022200255A1; CN116600686A

Abstract

The invention relates to a water tank (1) for a domestic appliance, comprising a connection for a filter cartridge, wherein an annular tank sealing surface for tight connection of the filter cartridge is provided on the tank bottom and the tank sealing surface surrounds a tank through-opening for the flow of the water from the filter cartridge through the wall of the tank bottom to the domestic appliance. The water tank is characterized in that the tank sealing surface has, along its periphery, a varying radius with respect to a central axis, such that the tank sealing surface has radial recesses and/or radial bulges, the bulges and/or recesses having a round profile.

Description

"Water tank with filter cartridge"

The invention relates to a water tank with a filter cartridge according to the preamble of claim 1.

Filter cartridges are regularly used in water-carrying household machines with a water tank, in particular in beverage machines such as coffee machines, tea machines, etc., in order to improve the water quality in accordance with the intended application. Filter media for water softening, such as ion exchange resin, or to improve the taste, such as activated carbon, are often used in such filter cartridges. The dosed addition of additives, e.g. for health or taste improvement, such as the addition of minerals or vitamins, etc., is already provided for in combination with filter media.

Water tanks of such machines according to the prior art regularly have tank connection elements on the tank bottom with an annular tank sealing surface for the tight connection of a filter connection element of the filter cartridge provided for such a water tank, which enclose a tank passage opening in the tank bottom for the water to flow from the filter cartridge and the water tank to the household appliance.

Such water tanks and filter cartridges are described, for example, in the publications DE 102004 050 877 A1, EP 1867 626 A1 and DE 197 17 056 C2.

To prevent unsuitable filter cartridges from being used, the tank connection elements have already been included Provided coding elements, so that only to these coding elements matching filter cartridges can be used. In certain embodiments, which are disclosed for example in the publications EP 2433 906 B1, EP 2065 972 B1, EP 2050 220 B1, EP 2 050 221 B1 and EP 2 050218 B1, a polygonal shape of the filter sealing surfaces and the tank sealing surfaces is provided for coding , so that the seal itself has an additional coding function in addition to the sealing function.

These designs have the disadvantage that the angular contour makes it more difficult to implement the sealing function compared to a round contour.

The object of the invention is therefore to further develop such a water tank and such a filter cartridge in such a way that the coding function mentioned is made possible without such disadvantages.

Starting from a water tank and a filter cartridge according to the preamble of claim 1, this object is achieved by its characterizing features.

In the following, elements to be assigned to the water tank are given the beginning of the word "tank" and elements to be assigned to the filter cartridge are given the beginning of the word "filter". Features of advantageous embodiments and developments of the invention are described below in such a way that they are not mandatory, but can be present.

The filter cartridge of a water tank according to the invention is provided with a filter housing whose wall is a The inside of the housing is separated from the outside of the housing in a watertight manner, with a filter inlet opening, which is arranged on the lower end area of the filter cartridge in the operating position and is open to the outside of the filter housing, being provided for water to enter from the water supply without any further connection elements, which accordingly when used in a water tank in the operating position of the filter cartridge connected to the inside of the tank. In relation to the direction of flow during operation, downstream of the filter inlet opening, a device for water pipework is provided inside the filter housing, which comprises at least one filter chamber having at least one filter medium and ends in a filter outlet opening for sucking water out of the filter cartridge. A filter connection element is provided with an annular filter connection piece, which has an annular filter sealing surface for the tight connection of the filter cartridge to a tank sealing surface in the water tank.

Such a filter cartridge differs in this configuration from filter cartridges to filter devices whose housings are connected tightly to water pipes of a water network with pressure-resistant connections and are thus integrated into the water network.

A filter cartridge according to the invention has a filter sealing surface, the course of which along the circumference of the annular filter connection piece has a varying radius in relation to a central axis, so that the filter sealing surface comprises radial bulges and/or radial indentations, the bulges and/or indentations having a round course, so that corners or edges are avoided. As a result, there are further possibilities for coding. This shape of the filter sealing surface matches a corresponding shape of a tank sealing surface, with the curvatures changing from the outside to the inside and vice versa over the course of the circumference making it more difficult or completely impossible to clamp or press a shaped seal that is not adapted in shape onto or into a fixed tank-side contact surface . The radial bulges and/or indentations mimic the shape of an annular spring, the circumference of which can be resiliently expanded or compressed. The spring effect also improves the sealing effect, since the filter sealing surface is pressed flat against the associated tank sealing surface by the spring pressure. The filter sealing surface and the tank sealing surface can also be used to fix the filter cartridge and then form a filter fixing surface or a tank fixing surface. This fixing function in the interaction of the filter sealing surface and the tank sealing surface is improved by such a spring effect.

The resilient deformability of the filter sealing surface can be improved in that the annular filter connecting piece of the filter connecting element having the filter sealing surface has an annular wall in the region of the filter sealing surface with a wall inside and a wall outside that run parallel or inclined to one another. Depending on whether the connecting piece is pushed onto a tank fixing surface or plugged into a tank sealing surface, either the wall outside or the wall inside of the annular wall comprises or forms the filter sealing surface.

Since in this embodiment the side of the wall opposite the filter sealing surface has the same shape with a correspondingly larger or smaller circumference, this wall is designed overall as an annular spring. The Ring Wall then forms an annular spring with parallel or mutually inclined peripheral sides.

The ring-shaped filter connecting piece of the filter connecting element, which has the filter sealing surface, can consist of a plastic that is more dimensionally stable at the operating temperature than an elastomer, at least in the area of the filter sealing surface. Due to this strength, the filter connection piece of the filter cartridge is able to exert a contact pressure on a tank-side tank sealing surface in order to establish the tight connection without impairing its shape.

Such a dimensionally stable plastic is stronger than an elastomer, so that an elastomer seal on the water tank side can be deformed with the filter connection piece. A contact pressure can be generated as a result. Deformation of an elastomeric seal can also cause one or more additional functions of the elastomeric seal, for example a mechanical or hydraulic function such as a fixing function, a valve function or the like.

This is advantageous, for example, when the filter sealing surface forms an outer surface of the ring-shaped filter connecting piece of the filter connecting element, pointing away from a central axis of the filter outlet opening. Such a filter connection piece, despite the changing circumferential curvatures, is able to exert a contact pressure outwards essentially over the entire circumference when it is inserted into a water tank-side water tank seal with a correspondingly radially inward-facing tank sealing surface in order to achieve the desired sealing effect and/or fixing effect. In a development of the invention, the arrangement of the bulges and indentations of the filter sealing surface is rotationally symmetrical over the circumference. This results in a restoring force of the annular spring that is evenly distributed over the circumference with a more stable fixation and sealing of the filter cartridge in the installed position. A rotationally symmetrical design of the filter sealing surface over the circumference results when the bulges and/or indentations are designed to periodically oscillate around a circular line. This allows for different angular positions of the filter cartridge, making it easier to connect. In addition, other technical functions can also be provided depending on the angle.

A more stable fixation of the filter cartridge in the installation position is achieved by arranging the bulges and indentations of the tank sealing surface and/or the filter sealing surface with the same angles over the circumference Deform bulges as well as in the area of the indentations.

The sealing effect of the filter sealing surface with the tank sealing surface is improved by a round profile of the bulges and/or indentations, so that corners or edges are avoided. Due to the round shape, avoiding corners or edges in the area of the sealing surfaces, the sealing function is improved, for example compared to polygonal shapes as in the prior art. An improvement in the mechanical clamping and thus the fixation is also possible due to the varying radius, for example compared to a circular shape. The bulges and indentations of the filter fixing surface can form a waveform along a circular line, the waveform consisting of an alternating sequence of convex circle segments forming the bulges and concave circle segments forming the indentations. A radially directed spring effect results from the course following a circular line.

The spring action of the ring spring can be further improved if the concave and convex circle segments are connected tangentially at turning points at the transition between concave and convex curvatures.

In a specific embodiment of the invention, the arc length of the convex circle segments is longer than the arc length of the concave circle segments. The swept angle of the convex circle segments is therefore greater than the swept angle of the concave circle segments. As a result, the tangential transition between the curves runs obliquely in relation to a central circle of the ring spring, so that no radially inward or outward-directed force arises in the transitions during the deformation.

In a specific embodiment, the convex and the concave circle segments have the same segment radius. This results in a comparable force distribution within the segments during deformation.

The circle segments can be arranged so that the convex and concave circle segments lie within an outer enveloping circle and outside of an inner enveloping circle, with the circle centers of the convex circle segments inside the inner enveloping circle and the circle centers of the concave circle centers lie outside the outer enveloping circle.

This shape results in a flat progression in relation to the enveloping circles or circle segments running along a center line between the enveloping circles, as a result of which the widening or shrinking of the annular spring is facilitated.

A good function has been shown when the radius of the inner enveloping circle is between 5% and 15% of the radius of the outer enveloping circle.

Furthermore, it has proven to be advantageous if the radius of the convex and/or concave circle segments is between 20% and 35% of the radius of the outer enveloping circle.

The spring action of such a spring washer is also beneficial if the wall thickness between the outside of the wall and the inside of the wall running parallel or inclined thereto is between 7% and 10% of the radius of the outer enveloping circle.

In addition, a course has been shown to be advantageous when the turning points between the curvatures of the concave and convex circle segments are closer to the inner enveloping circle than to the outer enveloping circle.

The filter sealing surface can form an outer surface of the ring-shaped filter connection piece of the filter connection element pointing away from a central axis of the filter outlet opening. Such a filter connection piece, despite the changing circumferential curvatures, is able to exert a resilient contact pressure outwards essentially over the entire circumference when it is inserted into an opening on the water tank side with a correspondingly radially inward-facing tank fixing surface in order to achieve the desired sealing and/or fixing effect . Vice versa When plugging onto a tank connection on the water tank side with a correspondingly radially outward-facing tank sealing surface, a resilient contact pressure can be exerted inwards essentially over the entire circumference by a radially inward-facing filter sealing surface in order to achieve the desired sealing and/or fixing effect.

In a particular embodiment of the invention, a filter fixing surface is provided both on the inside and on the outside of the filter connection piece, one or both of which simultaneously form a filter sealing surface.

Such a filter connection piece can be inserted into an annular slot on the tank side, the side walls of which each form a tank fixing surface and/or a tank sealing surface.

A constellation that works very well has been found, for example, when six bulges and six indentations are provided along a circular line that has a diameter of less than 3 cm.

The filter inlet opening of the filter cartridge can be designed as an annular sieve opening on the outside of the filter connection piece, as a result of which the filter cartridge in the water tank is open to the water contained therein.

The filter cartridge is improved if a guide structure for guiding and receiving a centering element on the water tank side is provided within the filter connecting piece. The filter cartridge can thus be aligned in the axial direction when it is inserted into the associated water tank and fixed in this alignment in the operating position. If the guide structure has at least one guide groove running in the axial direction, i.e. running parallel to the central axis, for receiving at least one guide rib of the centering element on the water tank side, this guide structure can interact with the associated centering element on the water tank side with the axial movement of the filter cartridge when it is inserted into the Water tank out in at least one angular position and additionally fixed there.

In order to provide guidance and fixation in a number of angular positions, the guide structure can have a number of guide grooves distributed around the circumference.

Good guidance of the filter cartridge into the desired angular position results when the wall of the guide grooves is rounded in such a way that the width of the grooves tapers from bottom to top in relation to the operating position. The guidance of the filter cartridge can also be improved if the walls of the guide grooves are rounded in such a way that the width of the grooves tapers radially from the inside to the outside. The combination of the two tapering groove shapes results in a type of funnel effect for a rib of a centering element on the water tank side that enters such a groove.

The groove shapes mentioned can be formed, for example, by means of inner curvatures in a wall of the guide structure connecting the guide grooves.

The shape of the filter sealing surface according to the invention can also be used to improve the fixation of the filter cartridge, in that the filter sealing surface is also provided as a filter fixing surface. The form of the invention as a filter fixing surface The provided filter sealing surface facilitates a deformation of the filter connecting piece in the area of the filter fixing surface, since the radial bulges and/or indentations form the shape of an annular spring, the circumference of which can be expanded or compressed in a resilient manner. Such a deformation facilitated by the varying radius makes it possible to improve the mechanical clamping and thus the fixation, for example in comparison with a circular shape or a polygonal shape.

The resilient deformability of the filter fixing surface can be improved in that the ring-shaped filter connection piece of the filter connection element that has the filter fixing surface has a ring-shaped wall in the region of the filter fixing surface with a wall inside and a wall outside that run parallel or inclined to one another. Depending on whether the connecting piece is pushed onto a tank fixing surface or plugged into a tank fixing surface, either the inner surface or the outer surface of the ring-shaped wall comprises or forms the filter fixing surface.

Since in this embodiment the side of the wall opposite the filter fixing surface has the same shape with a correspondingly larger or smaller circumference, this wall is designed overall as an annular spring. The annular wall then forms an annular spring with parallel or mutually inclined peripheral sides.

Furthermore, the ring-shaped filter connecting piece of the filter connecting element can have an outer and/or inner wall which is beveled relative to the vertical, so that the outer wall and the inner wall converge from top to bottom in relation to the operating position of the filter cartridge. Through this the result is a guide aid that facilitates the insertion of the connecting piece into a gap between two suitably shaped tank-side surfaces, wherein the tank-side surfaces can at least partially form an inner and/or outer tank sealing surface.

Accordingly, the beveled outer wall can have an outer filter sealing surface and/or the beveled inner wall can have an inner filter sealing surface in order to enter into a sealing form fit with the corresponding tank sealing surface.

The water tank for a household appliance that corresponds to the above-mentioned filter cartridge has a tank bottom, with an annular tank sealing surface being provided on the tank bottom for the tight connection of the filter cartridge, which encloses a tank passage opening for the water to flow out of the filter cartridge through the wall of the tank bottom to the household appliance. For advantageous interaction with the filter sealing surface described above, the course of the tank sealing surface also has a varying radius along its circumference relative to a central axis, so that the tank sealing surface comprises radial indentations and/or radial bulges.

This results in the coding options shown above for the filter cartridge on the water tank side. Due to this shape of the tank sealing surface, a filter cartridge with a corresponding filter sealing surface can be used in the water tank as described above. For the adaptation of the filter cartridge and tank-side connection, the selection of the materials and their arrangement can also be decisive and thus part of the coding due to this shape. Corners or edges can be avoided in the area of the sealing surfaces, which, for example, compared to polygon shapes from the State of the art, the sealing function is improved. An improvement in the mechanical clamping and thus the fixation is also possible due to the varying radius, for example compared to a circular shape.

The ring-shaped tank sealing surface and/or the ring-shaped filter sealing surface are preferably designed to be radially sealing over their entire, closed circumference. In this way, a continuous sealing ability of the respective sealing surface is achieved over the entire circumference, the size of the respective sealing surface being adaptable to the desired application over its axial extent.

The tank sealing surface is designed to match the above-mentioned filter sealing surface in such a way that the annular tank sealing surface forms an inner surface of a tank connection element pointing towards the central axis of the tank passage opening. Such a tank sealing surface matches the shape of the filter-side filter connection piece, so that it can be inserted into the tank connection element. Despite the changing circumferential curvatures when the filter connection piece is inserted into the tank connection element with the tank sealing surface pointing radially inwards, the desired sealing effect can be achieved essentially over the entire circumference.

For the use of a filter cartridge in which the indentations and/or bulges of the filter sealing surface are designed to periodically oscillate around a circular line as above, the indentations and/or bulges of the tank sealing surface are also designed to periodically oscillate around a circular line to match the filter sealing surface. Likewise, to adapt to a correspondingly shaped filter sealing surface Indentations and / or bulges of the tank sealing surface have a round course.

To adapt to a correspondingly shaped filter sealing surface, six indentations and six bulges along a circular line with a diameter of less than 3 cm can also be provided on the side of the tank sealing surface.

With the individual adaptations of the tank sealing surface to a correspondingly shaped filter sealing surface, the respective advantages that are mentioned above with regard to the filter cartridge can also be achieved.

The annular tank connection element can comprise an annular elastomeric seal in which the radial bulges and/or radial indentations are preformed. Such a tank connection element is particularly advantageous in connection with a filter cartridge whose ring-shaped filter connection piece consists of a plastic that is dimensionally stable at the operating temperature in the area of the filter sealing surface. The elastomer seal yields to the dimensionally stable plastic on the side of the filter cartridge when the filter cartridge is inserted.

The elastomer seal preferably has the tank sealing surface that seals against the filter cartridge on the inside of the radial bulges and/or radial indentations.

Furthermore, it is advantageous if the tank sealing surface of the elastomer seal has a sloping profile leading from top to bottom towards the central axis. This progression means that the elastomer seal is increasingly elastically deformed outwards during the insertion process of the filter cartridge and by the resulting restoring force creates a contact pressure that ensures the desired sealing effect.

By deforming an elastomer seal, one or more other functions can be effected in addition to the fixing function and the sealing function. This can, for example, also be a hydraulic function such as a valve function or the like.

For the use of an elastomeric seal, it is advantageous if the tank bottom comprises a fastening ring and an elastomeric seal inserted into the fastening ring. The external fastening ring then prevents the elastomer seal from expanding, so that the elastic restoring force of the elastomer is almost completely available for generating the contact pressure.

In order to avoid a flow between the fastening ring and the elastomeric seal, the elastomeric seal can have a sealing surface for the tight closure of the elastomeric seal with respect to the fastening ring. Furthermore, the elastomer seal can have a sealing surface for the tight closure of the fastening ring with respect to the tank bottom.

Advantageously, a bypass channel for unfiltered water can also be provided in the tank bottom, which runs out of the water tank interior through the fastening ring and through the elastomer seal. This allows drainage from the water tank if no filter cartridge is used. Such a drain may be required when no filter cartridge is available or operation without a filter cartridge is required, for example in a maintenance operation such as cleaning or descaling the associated machine. The cleaning or descaling agents used in such cases should not get into a filter cartridge.

The bypass channel can, for example, comprise an annular gap in the elastomer seal, so that water flows into the outlet line, distributed over the circumference.

The elastomeric seal preferably includes a closure element, by means of which the bypass channel can be closed, in particular by inserting the filter cartridge into the elastomeric seal. As a result, the bypass can be closed without further measures when using a suitable filter cartridge.

The elastomeric seal can be formed, for example, in such a way that the closure element comprises two opposite annular sealing surfaces in the annular gap, through which the annular gap can be closed when the elastomeric seal is deformed. If the inner sealing surface of the two ring-shaped sealing surfaces is widened when a filter cartridge is inserted into the elastomer seal, then a form fit with the outer ring-shaped sealing surface is to be effected, with the bypass channel being closed.

For easy attachment of the attachment ring and/or the elastomeric seal to the tank bottom, the attachment ring can include a latching element for latching to the tank bottom.

Furthermore, a centering element for insertion into the filter cartridge can be provided on the tank bottom. Such a centering element can be used to guide the insertion of a filter cartridge into the correct operating position. In addition, the shape of the centering element can also be used for further coding to ensure that only suitable filter cartridges are used. In addition, a fixing function can also be exercised with such a centering element, for example against twisting or tilting of the filter cartridge. The unintentional loosening of the filter cartridge can also be prevented by appropriate friction surfaces, so that a corresponding frictional force has to be overcome when the filter cartridge is removed. Additional fixing elements can also be attached to the centering element.

To connect the centering element to the elastomeric seal, the centering element can have a base plate that lies in a receptacle in the elastomeric seal and engages behind it at the edge. The centering element is thus attached to the tank bottom by the elastomer seal.

If a bypass of unfiltered water is provided, the centering element can have a bypass opening, for example in the base plate, which is open to the central drain.

The centering element preferably comprises a centering mandrel which protrudes upwards from the base plate of the centering element and has an annular outer surface which has a varying radius with respect to the central axis, so that the outer surface comprises radial indentations and/or radial bulges. Such a centering mandrel is adapted to the outer contour of the elastomer seal and the filter connection piece of the associated filter cartridge.

In a preferred embodiment of the invention, the indentations and/or bulges of the outer surface of the centering mandrel periodically oscillate around a circular line educated. This design corresponds to the shape of a corresponding elastomer seal and thus only leaves an annular gap with the indentations and/or bulges free for inserting a suitable filter cartridge. This configuration therefore prevents the use of a connection geometry of a different shape within the elastomer seal and thus improves the coding. In addition, on the inside of the filter connection piece along its bulges and/or indentations, the

Filter connection nozzle to reliably deform the elastomer seal when inserting the filter cartridge on the opposite outside.

The indentations and/or bulges of the outer surface of the centering mandrel can have a round profile to adapt to the shape of the elastomer seal and/or the filter connection piece.

If the elastomer seal and/or the filter connection piece are positioned accordingly, six indentations and six indentations along a circular line with a diameter of less than 3 cm are provided on the outer surface of the centering mandrel to adjust it.

In an advantageous embodiment, above the outer surface with the indentations and/or bulges, there is a step and an inwardly offset projection which is inserted further into the filter cartridge and thus offers a greater axial guide length.

To prevent an axial seal on this gradation by an unsuitable filter cartridge above the annular outer surface at least one in the extension of the peripheral surface upstanding tooth can be arranged.

At least one passage opening leading to the tank passage opening can be provided in the centering element above the annular outer surface, which passage opening connects the water inlet into the filter cartridge with the water outlet and is closed only by a filter cartridge sealing according to the invention.

The axial guidance and centering can be improved in that at least one guide rib is provided in the centering element above the annular wall. A water flow is possible next to this guide rib or, in the case of several guide ribs, between them. These guide ribs can be guided in the above-mentioned guide grooves when attaching a filter cartridge.

A further guidance aid for the centered insertion of the filter cartridge results from the fact that the guide rib or guide ribs are bevelled at the top towards the central axis. The filter connection piece can slide along these bevels when it is attached until it reaches the centered position.

The elastomeric seal can also have a sealing surface for the tight closure of the fastening ring with respect to the tank bottom in order to ensure that no unwanted water from the water tank flows past the filter cartridge via the fastening ring.

The fastening ring can also include a latching element for latching the fastening ring to the insert or to the tank bottom. This completes the assembly of the fastening ring relieved. If the centering element is also held by the fastening ring, as above, its assembly and possibly also the assembly of the water tank valve located underneath is simplified.

The design of the water tank is simplified if an insert part belonging to the tank bottom is provided on the tank bottom, which insert includes the parts provided on the water tank side for connecting the filter cartridge. With one insert, different port structures can be easily manufactured in the same water tank design by using different inserts. In addition, different requirements for the production tolerance of the water tank and the respective insert can be selected.

Such an insert can advantageously contain the elastomeric seal and/or the fastening ring and/or the centering element and/or at least partially the bypass channel. All the essential tank connection structures can be provided on the insert, so that the water tank can only be adapted to a specific filter cartridge by selecting the appropriate insert.

An embodiment of the invention is shown in the drawing and is explained in more detail with reference to the following figures»

show in detail

Fig.l is a perspective view of a tank bottom with inserted filter cartridge according to the prior art, 2 shows a perspective exploded view of a tank bottom with centering element and fastening ring,

3 shows a perspective view of the tank bottom according to FIG. 2 with installed centering element and installed fastening ring,

4 shows a top view of the tank bottom according to FIGS

3,

5 is a perspective view of the connection area of the filter cartridge viewed from the side,

6 shows a perspective representation of the connection area of the filter cartridge viewed obliquely from below,

7 shows a perspective view of a filter cartridge cut open at the level of the filter connection piece, inserted in a tank bottom,

8 shows a perspective view of a filter cartridge cut open at the level of the guide grooves, inserted in a tank bottom,

9 is a perspective view of a filter cartridge inserted into a tank bottom,

10 is a perspective view of the centering element,

11 shows a sectional view of a tank bottom without a filter cartridge with the water tank valve open, 11a and b two enlarged sections from FIG. 11 to illustrate a closable bypass line in the tank seal,

FIG. 12 shows a sectional view of a tank bottom according to FIG. 11 with a filter cartridge inserted,

Fig. 12a an enlarged detail from FIG. 12 to illustrate the closed bypass line,

13 shows a schematic end view of a filter connecting piece according to the invention,

FIG. 13a shows an enlargement of a detail from FIG. 13 and

14 shows a section of the filter cartridge showing the connection area to illustrate a guiding aid by bevels on the connecting piece.

Fig. 1 illustrates the usual configuration of a water tank 1 of a beverage machine, such as a coffee machine, e.g. The water tank 1 comprises a tank bottom 2 and water tank side walls 3 partially shown with dashed lines. A filter cartridge 4 with a filter housing 5 is inserted into the water tank 1 . The connection between the tank bottom 2 and the filter cartridge 4 is realized via tank connection elements 6 on the side of the water tank and filter connection elements 7 on the filter side.

The filter cartridge 4 is located in the interior 8 of the water tank 1, ie it is fully or partially in operation in the Water tank 1 stored water. 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 .

2 shows a round section of the tank bottom 2, with a fastening ring 10 and a centering element 11 for insertion into a recess 12 in the tank bottom 2 being provided. A tank valve body 13 with a seal 14 designed as an O-ring, from which two pins 15 protrude upwards, can also be seen in FIG. The fastening ring 10 also carries an elastomeric seal 16.

In FIGS. 3 and 4, the fastening ring 10 and the centering element 11 are installed in the tank bottom 2. It can be seen here that the pins 15 can pass through the centering element and thus form coding elements for coding the water tank in relation to the associated machine connection, from which the tank valve body 13 must be actuated when the water tank is inserted. It is also clearly visible in Fig. 4 that the elastomeric seal 16 forming the water tank seal 17 is an annular seal which has 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 has radial indentations 19 and radial bulges 20. The first tank sealing surface 18 is designed to be radially sealing over its entire, closed circumference and at the same time serves as the first tank fixing surface.

In Fig. 5 the connection area 21 of a suitable filter cartridge 22 is shown. A filter connection piece 23 forms an inner ring 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 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 forms, at least partially over a certain axial extent, a filter sealing surface 28 which is designed to be radially sealing over its entire, closed circumference. The outer surface, in particular in its area designed as a filter sealing surface 28, and/or the inner surface 68 of the filter connecting piece 23 can at least partially serve as a filter fixing surface at the same time.

In addition to the parts of the connection area 21 of the filter cartridge 22 described above, the view in FIG. 6 shows the special configuration of a guide structure 31 of the filter cartridge 22 for receiving the centering element 11 . The guide structure has guide grooves 32 which are aligned with the edges 33 of a polygonal ring 34, in the present example with six guide grooves which are aligned with six edges of a hexagonal ring. In the sectional view with a view from above according to Fig. 7, the sectional plane goes through this polygonal ring 34.

Inner curves 35 which lie between the edges 33 and the guide grooves 32 adjoin upwards into the interior of the filter cartridge. The inner curves 35 form the side walls 36 of the guide grooves 32 . Due to this arched 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 sectional plane runs at a height at which the guide grooves 32 are clearly formed. A riser pipe 37 is connected centrally on the inside, through which the water entering the filter cartridge 22 is directed upwards to the filter section.

In Fig. 9 the entire filter cartridge 22 is shown. In a filter housing 37, which has an optional lateral dosing opening 38 and the water connection on the bottom described.

The optional dosing opening 38 is only provided in the case of an embodiment of the filter cartridge that is used for dispensing additives, e.g. B. minerals, vitamins or the like., Is formed from a housed in the filter housing 37 dosing chamber in the water supply. Since such a dosing chamber is closed within the filter housing 37 with respect to the filter section, it has no further significance with regard to the filtration. A filter cartridge according to the invention can therefore also be constructed without further ado without this dosing chamber and its dosing opening 38 . In particular, the operating position can be seen in FIG. 9, to which the statements above and below in this description relate.

A perspective representation of the centering element 11 can be seen in FIG. The centering element is provided with a base plate 39 which, in the mounted state, lies in a receptacle of the elastomer seal and engages behind the edge of the latter. A centering mandrel 40 protrudes upwards from the bottom 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 has radial indentations 42 and bulges 43 . The outer surface 41 is thus adapted to a corresponding shape of the filter connection piece 9 . For further adjustment, the indentations 42 and bulges 43 of this outer surface 41 are also designed to periodically oscillate around a circular line and have a round shape. In the illustrated embodiment, six indentations 42 and six bulges 43 are provided along a circular line with a diameter of less than 3 cm, corresponding to the design of the illustrated embodiment of the filter cartridge 22 . With a different filter cartridge, the adaptation of the outer surface 41 or the second tank fixing surface must be modified accordingly.

All adjustments to the outer surface 41 of the centering mandrel 11 result in only an annular slot between the outer surface 41 and the elastomeric seal 16 for inserting the filter connecting piece 23 being open when installed. This results in a further coding against the use of an unsuitable filter cartridge. In addition, in this way it is possible to support the filter connecting piece 23 on its inside on the outer surface 41 of the centering mandrel 11 . In this way, the contact pressure of the filter connection piece on the elastomer seal 16 can be increased uniformly over the varying shape along the entire peripheral shape.

At least one upwardly projecting tooth 44 is provided above the annular outer surface. The one or more teeth 44 are mounted on a step 45 of the centering mandrel 40 . Further, the shape of the outer surface 41 following increases 46 over the gradation 45 are attached at a distance from the teeth 44, so that between the teeth and the increases 46 a gap 47 remains. The tooth or teeth 44 and/or ridges 46 may prevent the use of an axial seal to bypass the key. Above the outer surface 41 there is also a passage opening 48 provided, which leads to a tank passage opening in the assembled state of the centering element 11 . The filtered water of a filter cartridge 22 can be discharged from the water tank through this passage opening 48 .

One or more bottom vents 49 are provided in bottom panel 39 below outer surface 41 . Unfiltered water can be routed out of the water tank through these openings in the bottom. Below the elevations 46 and within the wall bearing the outer surface 41 there is a cavity 50 for receiving the tank valve body 13.

Provided above the annular outer surface 41 are guide ribs 51 which can be beveled on their upper side as in the exemplary embodiment shown. The guide bevels 52 formed in this way help when inserting the guide ribs 51 into the guide grooves 32 of a filter cartridge 22. In the sectional representation according to FIG.

11, 11a, 11b, 12 and 12a the assembled components of the water tank 1 for the connection of a filter cartridge with and without a filter cartridge 22 are shown. The fastening ring 10 is provided with a latching projection 53 with which it can latch on the tank bottom 2 by engaging behind a bottom rib 54 of the water tank. The elastomeric seal 16 has a bottom section 55 which engages under the fastening ring 10 and thus holds the elastomeric seal 16 with the fastening ring 10 on the tank bottom 2 .

For the seal against the tank bottom 2, the elastomeric seal 16 has a sealing surface that is present through a sealing bead 56 is realized. A circumferential sealing surface can be provided at various points for the tight closure of the elastomer seal 16 in relation to the fastening ring 10 . In the exemplary embodiment shown, a ring seal 57 is provided which is formed on top of the elastomer seal 16 and seals with the latter in a sealing groove 58 of the fastening ring.

The elastomeric seal 16 includes an outer ring 59 and an inner ring 60 which are integrally molded and bonded together. Outer ring 59 and inner ring 60 both follow in shape circumferentially the varying radius of mounting ring 10, filter port 23 and elastomeric seal 16 and the indentations and bulges formed thereby. The outer ring 59 is stepped and carries the ring seal 57 and the sealing bead 56. The outer ring 59 is also provided with one or more bypass openings 61 through which unfiltered water can enter the annular gap 62 between the outer ring 59 and the inner ring 60 in the flow direction PI. In the installed state, the bypass opening 61 of the elastomeric seal 16 is located directly after a bypass opening 63 in the fastening ring 11, which can also be seen in FIGS. 1 and 3, for example. Through the bypass opening 63, unfiltered water can flow out of the annular gap 62 from the water tank 1 in the direction P2 into the corresponding beverage machine.

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 can be seen in FIG. 11, so that the unfiltered water guided in the bypass can flow out of the annular gap 62 in flow direction P2. In this state, the inside 66 of the Inner ring 60, which forms the water tank seal 17, chamfered in the course down inwards. The configuration of the bypass is emphasized in the enlargements according to FIGS. 11a and b.

When inserting a filter cartridge 22 with the filter connection piece 23, the elastomer seal 16 is deformed so that the inside 66 is pressed outwards and runs essentially perpendicularly along the filter connection piece. The sealing lip 64 is pressed onto the opposite sealing surface 65 and thus the annular gap 62 and thus also the bypass through the bypass openings 61, 63 are closed. The deformation generates a contact pressure that presses the tank sealing surface 17 against the filter sealing surface 28 and at the same time the sealing lip 64 against the sealing surface 65 . This condition is shown in Figures 12 and 12a.

The tank valve body 13 is shown both in Fig. 11 and in Fig.

12 is raised by a stop (not shown) of the associated machine against a return spring 67 into the cavity 50 and is thus in the open position, which corresponds to the water tank used. If the water tank is removed from the machine, the tank valve body 13 closes under the pressure of the return spring 67.

The tank sealing surface 18 is formed by the inside 66 of the elastomeric seal 16 and at the same time represents a first tank fixing surface 18. As mentioned above, a first filter fixing surface 28 formed by the filter sealing surface 28 rests on this side when the filter cartridge 5, 22 is in the inserted state, under a contact pressure. which deforms the elastomeric seal 16 in such a way that a fixing and sealing form fit is achieved. A second filter fixing surface 68 (see FIG. 5), which is formed by the inner surface of the filter connecting piece 23, is in contact with the outer surface 41 forming the second tank fixing surface. This form fit is also formed under contact pressure. Due to the shape of the filter connection piece 23 according to the invention, this forms an annular wall 69 which can be widened in a resilient manner if required.

This results in the possibility of tolerance compensation with a good fixation, which is caused by the corresponding tension. Due to the parallel or mutually inclined shape of the first filter fixing surface 28 and a second filter fixing surface 68, the ring-shaped, corrugated wall 69 of the connecting 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.

The filter connector according to the end view Fig. 13 and the enlarged detail according to Fig. 13a shows the described wave shape with bulges 29 and indentations 30. The annular wall 69 of the filter connector 23 with a wall thickness W has the first filter fixing surface 28 on the wall outside 71 and the first filter fixing surface 28 on the wall inside 72 the second filter fixing surface 68 on. The wall outside 71 and the wall inside 72 run parallel in the view shown, but are beveled towards one another in the axial direction, which will be explained further below. The waveform is therefore further illustrated by means of a center line 73 shown in broken lines.

The center line 73 undulates between an outer enveloping circle 74 whose radius has the greatest value of the varying radius, and an inner enveloping circle 75 whose radius is 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 circle segments 76 and wave troughs in the form of concave circle segments 77. In the illustrated embodiment, all circle segments 76, 77 have the same segment radius S. The centers 78, 79 of the circle segments 76, 77 are for the convex circle segments 76 within the inner enveloping circle 75 and for the concave circle segments 77 outside of the outer enveloping circle 74. The convex circle segments 76 and the concave circle segments 77 merge tangentially and are evenly distributed over the circumference, so that a rotationally symmetrical form. In the illustrated

In the exemplary embodiment, six convex circle segments 76 and six concave circle segments 77 are provided, which alternately lie at an angular distance of 30°, i.e. the convex circle segments 76 lie at an angle a of 60° apart from one another and the concave circle segments 77 likewise.

Due to the selection of the segment radius and the associated position of the associated center points 78, 79, the center line runs in a comparatively flat, curved, wavy manner 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 bulges 29 is significantly longer than the arc length of the indentations 30, as a result of which the angle g swept out by the segment arc of the bulges 29 is significantly greater than the angle d swept out by the indentations 30. This shape improves the spring effect of the filter connection piece 23.

For comparison, circle segments 81 are shown in the drawing, the segment centers 82 directly on the center line 73 lie. This course, which is not realized in this embodiment, has significantly smaller segment radii and a course that is essentially perpendicular to the center line 73 .

A good spring effect has been shown with radii and wall thicknesses in which 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 circle segments is between 20% and 35% of the radius of the outer enveloping circle 74 is located. The wall thickness W between the outside of the wall 71 and the inside of the wall 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.

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 circle segments is about 3.08 mm and the wall thickness between the outside of the wall 71 and the inside of the wall 72 running parallel or inclined thereto is about 0.9 mm.

In Fig. 14 it can be seen that the outer 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 by the angle col or ω2 relative to the vertical, so that they based on the operating position of the filter cartridge 4, 22 converge from top to bottom.

This bevel or bevels by the angle wΐ and/or ω2 form an insertion aid when inserting the connecting piece 23 into the annular gap between the elastomer seal 16 and the outer surface 41 of the water tank 1. Reference list:

1 water tank

2 tank bottom

3 water tank side wall

4 filter cartridge

5 filter housing

6 tank connection element

7 filter connection

8 interior

9 filter connectors

10 mounting ring

11 centering element

12 deepening

13 tank valve body

14 seal

15 pins

16 elastomer seal

17 Water tank seal/ring seal

18 tank sealing surface

19 indentation

20 bulge

21 connection area

22 filter cartridge

23 Filter Fittings/Inner Ring

24 Outer ring

25 lead

26 return

27 inlet screen

28 Filter sealing surface / outer surface

29 bulge

30 indentation 31 Management Structure

32 guide groove

33 edge

34 polygon ring

35 inner curvature

36 wall

37 filter housing

38 dosing opening

39 bottom plate

40 centering mandrel

41 outer surface

42 indentation

43 bulge

44 teeth

45 gradation

46 increase

47 gap

48 passage opening

49 floor passage opening

50 cavity

51 guide rib

52 guide slope

53 locking projection

54 bottom rib

55 floor section

56 sealing bead

57 ring seal

58 sealing groove

59 inner ring

60 outer ring

61 bypass opening

62 annular gap

63 bypass opening 64 sealing lip

65 sealing surface

66 inside

67 return spring

68 Second filter fixing surface/inner surface

69 wall

70 ring spring

71 wall outside

72 wall inside

73 center line

74 Outer enveloping circle

75 Inner enveloping circle

76 Convex circle segment

77 Concave circle segment

78 midpoint

79 midpoint

80 center circle line

81 circle segment

82 segment center

83 turning point

84 tank passage opening

A axis W wall thickness S segment radius P1 flow direction P2 flow direction

Claims

Patent Claims:

1. Water tank (1) for a household machine with a connection for a filter cartridge (22), with an annular tank sealing surface being provided on the tank bottom for the tight connection of the filter cartridge (22) and the tank sealing surface having a tank passage opening for the water to flow out of the filter cartridge (22 ) surrounded by the wall of the tank bottom to the household appliance, characterized in that the tank sealing surface (18) has a varying radius along its circumference relative to a central axis, so that the tank sealing surface (18) has radial indentations (19) and/or radial bulges (20 ) Includes, wherein the bulges (29) and / or indentations (30) have a round profile.

2. Water tank (1) for a household appliance according to claim 1, characterized in that the water tank (1) has a filter cartridge (22) with a filter housing

(37), the wall of which separates the inside of the housing from the outside of the housing in a watertight manner, with a filter inlet opening (27) which is arranged in the operating position of the filter cartridge (4) at its lower end area and is open to the outside of the filter housing (5), being related to the direction of flow during operation, downstream of the filter inlet opening (27), a device for water conduction is provided inside the filter housing (37), which comprises at least one filter chamber having at least one filter medium and in a filter outlet opening for sucking water out of the filter cartridge (22 ) ends, and wherein a filter connection element with an annular Filter connection piece (23) is provided, which has an annular filter sealing surface (28) for the tight connection of the filter cartridge (22) to a tank sealing surface in the water tank, the course of the filter sealing surface

(28) along the circumference of the annular filter connection piece (23) has a varying radius with respect to a central axis, so that the filter sealing surface (28) comprises radial bulges (29) and/or radial indentations (30), the bulges

(29) and/or indentations (30) have a round course.

3. Water tank (1) according to claim 1, characterized in that the annular tank sealing surface (18) and/or the annular filter sealing surface (28) are designed to be radially sealing over their entire, closed circumference.

4. Water tank (1) according to one of the preceding claims, characterized in that the annular filter connecting piece (23) of the filter connecting element, which has the filter sealing surface (28), consists of a plastic which is dimensionally stable at the operating temperature and is in particular stronger than a elastomer is.

5.Water tank (1) according to one of the preceding claims, characterized in that the filter sealing surface (28) forms an outer surface of the annular filter connecting piece (23) of the filter connecting element pointing away from the central axis (A) of the filter outlet opening.

6. Water tank (1) according to one of the preceding claims, characterized in that the arrangement of the bulges (29) and indentations (30) of the filter sealing surface (28) are formed rotationally symmetrically over the circumference.

7. Water tank (1) according to any one of the preceding claims, characterized in that the bulges (29) and / or indentations (30) are designed to oscillate periodically about a circular line.

8. Water tank (1) according to one of the preceding claims, characterized in that the arrangement of the bulges (29) and indentations (30) of the filter sealing surface (28) is formed with the same angles over the circumference.

9. Water tank (1) according to any one of the preceding claims, characterized in that the bulges (29) and / or indentations (30) have a round course.

10. Water tank (1) according to one of the preceding claims, characterized in that six bulges (29) and six indentations (30) are provided along a circular line which has a diameter of less than 3 cm.

11. Water tank (1) according to one of the preceding claims, characterized in that a guide structure for guiding and receiving a tank-side centering element (11) is provided within the filter connection piece (23).

12. Water tank (1) according to one of the preceding claims, characterized in that the guide structure (31) has at least one guide groove (32) for receiving at least one guide rib (51) of the tank-side centering element (11).

13. Water tank (1) according to one of the preceding claims, characterized in that the guide structure (31) has a plurality of guide grooves (32) distributed around the circumference.

14. Water tank (1) according to any one of the preceding claims, characterized in that the wall of the guide grooves (32) is rounded in such a way that the width of the grooves tapers from bottom to top in relation to the operating position.

15. Water tank (1) according to one of the preceding claims, characterized in that the wall of the guide grooves (32) is rounded in such a way that the groove width tapers from the inside to the outside.

16. Water tank (1) according to one of the preceding claims, characterized in that the tapering shape of the guide grooves is formed as an inner curvature (35) in a wall (36) connecting the guide grooves.

17. Water tank (1) according to one of the preceding claims, characterized in that the filter outlet opening (28) of the filter cartridge (22) (4) is designed as an annular screen opening (27).

18. Water tank (1) according to one of the preceding claims, characterized in that the annular filter connecting piece (23) of the filter connecting element having the filter sealing surface (28) has a wall (69) with a wall parallel or inclined to the inner side of the wall, at least in the region of the filter sealing surface (28). (72) running, the filter sealing surface (28) enclosing or forming wall outside (71).

19. Water tank (1) according to one of the preceding claims, characterized in that the annular filter connection piece (23) of the filter connection element has an outer (71) and/or an inner wall (72) which, in relation to the operating position of the filter cartridge, is opposite the vertical is beveled at an angle wΐ and/or w2, so that the outer wall (71) and the inner wall (72) of the filter cartridge converge from top to bottom.

20. Water tank (1) according to one of the preceding claims, characterized in that the beveled outer wall 71 has an outer (28) and/or the beveled inner wall 72 has an inner filter sealing surface.

21. Water tank (1) according to one of the preceding claims, characterized in that the tank sealing surface (18) forms an inner surface of an annular tank connection element pointing towards the central axis of the tank passage opening.

22. Water tank (1) according to one of the preceding claims, characterized in that the indentations (19) and/or bulges (20) are designed to oscillate periodically about a circular line.

23. Water tank (1) according to any one of the preceding claims, characterized in that the indentations (19) and / or bulges (20) have a round course.

24. Water tank (1) according to any one of the preceding claims, characterized in that six indentations (19) and six bulges (20) are provided along a circular line with a diameter of less than 3 cm.

25. Water tank (1) according to one of the preceding claims, characterized in that the annular tank connection element comprises an annular elastomeric seal (16) in which the radial bulges (19) and/or radial indentations (20) are preformed.

26. Water tank (1) according to one of the preceding claims, characterized in that the tank sealing surface (18) is arranged on the inside of the radial bulges (19) and/or radial indentations (20) of the elastomer seal (16).

27. Water tank (1) according to any one of the preceding claims, characterized in that the tank sealing surface (18) has a sloping profile leading from top to bottom towards the central axis (A).

28. Water tank (1) according to one of the preceding claims, characterized in that the tank bottom (2) comprises a fastening ring (10) and an elastomeric seal (16) inserted in the fastening ring (10).

29. Water tank (1) according to one of the preceding claims, characterized in that the elastomeric seal (16) has a sealing surface (57) for the tight closure of the elastomeric seal (16) relative to the fastening ring (10).

30. Water tank (1) according to one of the preceding claims, characterized in that the elastomer seal (16) has a sealing surface (56) for the tight closure of the fastening ring (10) relative to the tank bottom (2).

31. Water tank (1) according to one of the preceding claims, characterized in that a bypass channel for unfiltered water from the water tank (1) is provided in the tank bottom, which runs from the water tank interior through the fastening ring and through the elastomeric seal.

32. Water tank (1) according to any one of the preceding claims, characterized in that the bypass channel comprises an annular gap (62) in the elastomeric seal (16).

33. Water tank (1) according to any one of the preceding claims, characterized in that the elastomeric seal (16) comprises a closure element by means of which the bypass channel can be closed.

34. Water tank (1) according to one of the preceding claims, characterized in that the closure element comprises two opposite annular sealing surfaces (64, 65) in the annular gap (62), through which the annular gap (62) can be closed by deforming the elastomeric seal (16).

35. Water tank (1) according to one of the preceding claims, characterized in that the fastening ring (10) comprises a latching element (53) for latching the fastening ring (10) to the tank bottom (2).

36. Water tank (1) according to any one of the preceding claims, characterized in that a tank bottom Centering element (11) is provided for insertion into the filter cartridge (22).

37. Water tank (1) according to one of the preceding claims, characterized in that the centering element (11) has a base plate (39) which lies in a receptacle of the elastomeric seal (16) and engages behind it at the edge.

38. Water tank (1) according to one of the preceding claims, characterized in that a centering mandrel (40) protrudes upwards from the base plate (39) of the centering element (11) and has an annular outer surface (41) which has a varying radius compared to the central axis (A), so that the outer surface (41) comprises radial indentations (42) and/or radial bulges (43).

39. Water tank (1) according to one of the preceding claims, characterized in that the indentations (42) and/or bulges (43) of the outer surface (41) of the centering mandrel

(40) are designed to periodically oscillate around a circular line.

40. Water tank (1) according to any one of the preceding claims, characterized in that the indentations

(42) and/or bulges (43) of the outer surface (41) of the centering mandrel (40) have a round shape.

41. Water tank (1) according to any one of the preceding claims, characterized in that in the outer surface (41) of the centering mandrel (40) has six indentations (42) and six Bulges (43) are provided along a circular line with a diameter of less than 3cm.

42. Water tank (1) according to any one of the preceding claims, characterized in that above the annular outer surface (41) at least one upstanding tooth (44) is arranged.

43. Water tank (1) according to one of the preceding claims, characterized in that at least one passage opening (48) leading to the tank passage opening is provided in the centering element (11) above the annular outer surface (41).

44. Water tank (1) according to one of the preceding claims, characterized in that at least one guide rib (51) is provided in the centering element (11) above the annular outer surface (41) bearing wall.

45. Water tank (1) according to any one of the preceding claims, characterized in that the guide rib (51) or the guide ribs (51) are beveled at the top towards the central axis.

46. Water tank (1) according to one of the preceding claims, characterized in that an insert part belonging to the tank bottom is provided on the tank bottom and comprises the parts provided on the tank side for connecting the filter cartridge (22).

47. Filter cartridge for a water tank according to one of the preceding claims, characterized in that it is designed according to one of claims 2 to 19.