RU2824008C2 - Water reservoir with filter cartridge - Google Patents

Abstract

FIELD: technology of water and air purification.

SUBSTANCE: invention relates to a water reservoir for a household device with a connection for a filter cartridge. At the bottom of the water reservoir there is an annular sealing surface for tight connection of the filter cartridge, which surrounds the through hole of the reservoir, intended for water flow from the filter cartridge through the wall of the reservoir bottom into the household device. Water reservoir is characterized by that the shape of the sealing surface of the reservoir along its periphery has a varying radius relative to the central axis, so that the sealing surface of the reservoir has radial concavities and/or radial bulges, wherein the bulges and/or concavities have a rounded shape.

EFFECT: providing sealing and coding functions when placing a filter cartridge in a reservoir.

46 cl, 18 dwg

Description

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

In household machines that work with water and are equipped with a water tank, in particular beverage machines, coffee machines, tea makers, etc., filter cartridges are usually used to improve the quality of the water in accordance with the intended purpose. In such filter cartridges, filter media are often used to soften the water, such as ion exchange resin, or to improve the taste, such as activated carbon. In combination with filter media, it is also envisaged to dose additives, such as those that are beneficial to health or improve the taste, such as adding minerals or vitamins, etc.

Water reservoirs of such machines of the known level of technology are usually provided with connecting elements located on the bottom of the reservoir with an annular sealing surface for hermetically sealing the connecting element of the filter cartridge provided for this water reservoir, which surrounds a through hole in the bottom of the reservoir, ensuring the flow of water from the filter cartridge and the water reservoir into the household device.

Similar water tanks and filter cartridges are described, for example, in DE 10 2004 050 877 A1, EP 1 867 626 A1 and DE 197 17 056 C2.

In order to prevent the use of unsuitable filter cartridges, the connecting elements of the reservoir are provided with coding elements, as a result of which only a filter cartridge corresponding to a given coding element can be used. In certain embodiments, which are described, for example, in EP 2 433 906 B1, EP 2 065 972 B1, EP 2 050 220 B1, EP 2 050 221 B1 and EP 2 050 218 B1, a polygonal shape of the filter sealing surfaces and the reservoir sealing surfaces for coding is provided in such a way that, in addition to the actual sealing function, an additional coding function is ensured by means of the seal.

The disadvantage of these embodiments is the difficulty of ensuring a sealing function when mating an angular contour relative to a circular contour.

Thus, the objective of the invention is

improving such a water reservoir and such a filter cartridge in such a way that the implementation of the said coding function is possible without the said disadvantages.

This problem is solved in relation to a water reservoir and a filter cartridge according to the limiting part of paragraph 1 of the formula of the invention by means of distinctive features.

Further, in general, elements related to a water reservoir have in their name the end verbal component of "reservoir", and elements related to a filter cartridge have in their name the end component of "filter" and/or "filtering". The features of preferred embodiments and improvements of the invention are further described in such a way that their presence is not mandatory, but they can take place.

The filter cartridge of the water reservoir according to the invention has a filter housing, the wall of which watertightly separates the inner side of the housing from the outer side of the housing, wherein an inlet opening of the filter is provided, located in the operating position of the filter cartridge on its lower end region and open to the external environment of the filter housing, for the flow of water from the water reserve without additional connecting elements, which, accordingly, is connected to the internal space of the water reservoir, when the filter cartridge is installed in the water reservoir in the operating position. With respect to the flow direction during operation, after the inlet opening of the filter, a device is provided for feeding water into the internal space of the filter housing, which includes at least one filter chamber provided with at least one filter medium, and ends in the outlet opening of the filter for draining water from the filter cartridge. The connecting element of the filter is provided with an annular connecting nipple, having an annular sealing surface of the filter for hermetically connecting the filter cartridge with the sealing surface in the water reservoir.

The described design of the filter cartridge differs from the filter cartridges of filter devices, the body of which is hermetically connected to the water lines of the water supply network by pressure-resistant connections and, thus, is integrated into this water supply network.

The filter cartridge according to the invention has a filter sealing surface, the shape of which along the perimeter of the annular filter connecting nipple is characterized by a variable (varying) radius relative to the central axis, so that the filter sealing surface has radial convexities and/or radial concavities, wherein said convexities and/or concavities have a rounded shape, so that corners or ribs are absent.

This provides additional coding options. This shape of the filter sealing surface is combined with the corresponding shape of the sealing surface of the tank, whereby, due to the bends of the convexities or concavities alternating along the perimeter from the outside to the inside and vice versa, the pulling or pressing of the seal that does not fit the shape onto or into the rigid contact surface located on the tank side is complicated or completely eliminated. The radial convexities and/or concavities recreate the shape of an annular spring, the circumference of which can be spring-like stretched or compressed. In this case, the spring action improves the sealing action, since the spring pressure ensures a planar pressing of the filter sealing surface onto the corresponding sealing surface of the tank. The filter sealing surface and the sealing surface of the tank can also serve to fix the filter cartridge and in this case represent the filter fixing surface or the tank fixing surface. The spring action improves the fixing function in the interaction of the filter sealing surface and the tank sealing surface.

The elastic deformability of the filter sealing surface can be improved by the fact that the annular connecting nipple of the filter connecting element, provided with the filter sealing surface, has an annular wall in the area of the filter sealing surface with an inner side and an outer side that are parallel or inclined relative to each other. Depending on whether the connecting nipple is put on the fixing surface of the tank or inserted into it, either the outer side of the wall or the inner side of the annular wall forms the filter sealing surface.

Since in this configuration the side of the wall opposite the sealing surface of the filter has the same shape with, respectively, a larger or smaller circumference (perimeter), this wall is designed as a whole as an annular spring. Thus, the annular wall is an annular spring with peripheral sides parallel or inclined relative to each other.

The annular connecting nipple of the filter connecting element, provided with a filter sealing surface, at least in the area of the filter sealing surface, can be made of a polymer material characterized at the operating temperature by greater stability of shape (resistance to shape change) than the elastomer. Due to such rigidity, the filter connecting nipple of the filter cartridge can exert a pressing pressure on the sealing surface of the tank located on the tank side without any unfavorable change in shape, in order to ensure a hermetic seal.

The said dimensionally stable polymer material is more rigid (stable) than the elastomer, so that the filter connection nipple can deform the elastomer seal on the side of the water tank. In this way, a pressing pressure can be created. By deforming the elastomer seal, one or more other functions of the elastomer seal can also be realized, for example, a mechanical or hydraulic function, such as a locking function, a valve function, or the like.

This is advantageous, for example, when the sealing surface of the filter forms an outer surface facing away from the central axis of the filter outlet.

an annular connecting nipple of the filter connecting element. Despite the said alternating bends along the perimeter, such a filter connecting nipple, when installed in a seal of the water reservoir located on the side of the water reservoir with a corresponding radial inwardly facing sealing surface of the reservoir, is capable of exerting an outwardly directed pressing pressure substantially along the entire periphery in order to provide the desired sealing action and/or locking action.

In one of the improvements of the invention, the arrangement of the convexities and concavities of the filter sealing surface is performed rotationally symmetrically along the perimeter. Due to this, a uniform distribution of the return force of the ring spring along the perimeter is ensured with a more stable fixation and sealing of the filter cartridge in the mounted position. Rotational-symmetrical execution of the filter sealing surface along the perimeter is achieved when the convexities and/or concavities are formed with periodic oscillation around a circular line. Due to this, various angular positions of the filter cartridge are possible, which facilitates its attachment. In addition, other technical functions can be provided that depend on the angular position.

A more stable fixation of the filter cartridge in the built-in position is achieved by the fact that the arrangement of the convexities and concavities of the sealing surface of the tank and/or the sealing surface of the filter is performed with the same angular step along the perimeter. Consequently, the ring spring made in this way can be uniformly deformed along the perimeter both in the area of the convexities and in the area of the concavities.

The sealing effect of the filter sealing surface with the container sealing surface can be improved by the rounded shape of the convexities and/or concavities, so that corners or ribs are excluded. Due to the rounded shape without corners or ribs in the area of the sealing surfaces, for example, compared to the polygonal shapes of the prior art, the sealing function is improved. In addition, due to the variable radius, it is also possible to improve the mechanical clamping and thus the fixation, for example, compared to the round shape.

The convexities and concavities of the filter fixing surface can form a wave-like shape along a circular line, wherein the wave-like shape consists of alternating convex circular segments forming convexities and concave circular segments forming concavities. By following the circular line of motion (shape), a radially oriented spring action is provided.

The spring action of the annular spring can be further improved if the concave and convex circular segments at the inflection points during the transition between concave and convex bends are tangentially connected.

In one particular embodiment of the invention, the arc length of the convex circular segments is greater than the arc length of the concave circular segments. Thus, the described angle of the convex circular segments is also greater than the described angle of the concave circular segments. Consequently, the tangential transition between the bends is inclined relative to the average circumference of the annular spring, so that during deformation in the transitions, no radially inward or outwardly directed force arises.

In one particular embodiment of the invention, the convex and concave circular segments have the same segment radius. Due to this, when deforming within the segments, a comparable distribution of forces occurs.

The circular segments may be arranged so that the convex and concave circular segments lie inside the outer enveloping circle and outside the inner enveloping circle, with the center of the circle of the convex circular segments lying inside the inner enveloping circle, and the center of the circle of the concave circular segments lying outside the outer enveloping circle. Such a shape provides a gentle course relative to the said enveloping circles, respectively, the middle line of the circular segments passing between the enveloping circles, due to which the extension or compression of the annular spring is facilitated.

Proper operation is achieved when the radius of the inner envelope circle is between 5% and 15% of the radius of the outer envelope circle.

In addition, a variant in which the radius of the convex and/or concave circular segments is from 20% to 35% of the radius of the outer envelope circle has proven to be appropriate.

The spring action of such a spring ring is positively affected if the wall thickness between the outer side of the wall and the inner side of the wall, parallel or inclined relative to it, is from 7% to 10% of the radius of the outer enveloping circle.

In addition, a favorable course of action was found in which the inflection points between the bends of the concave and convex circular segments lay closer to the inner envelope circle than to the outer envelope circle.

The sealing surface of the filter can form an outer surface of the annular connecting nipple of the filter connecting element facing away from the central axis of the filter outlet. Despite the alternating bends along the perimeter, such a filter connecting nipple, when inserted into the opening located on the side of the water reservoir with a corresponding radially inwardly facing locking surface of the reservoir, provides an outwardly directed elastic pressing pressure substantially along the entire perimeter in order to achieve the desired sealing and/or locking effect. And vice versa, when put on a connecting nipple of a reservoir located on the side of the reservoir with a corresponding radially outwardly facing sealing surface of the reservoir, an inwardly directed elastic pressing pressure is provided by means of the radially inwardly facing sealing surface of the filter substantially along the entire perimeter in order to achieve the desired sealing and/or locking effect.

In one specific embodiment of the invention, both on the inner side and on the outer side of the filter connection nipple, a filter fixing surface is provided, of which one or both surfaces simultaneously form a filter sealing surface. Such a filter connection nipple can be inserted into an annular gap located on the tank side, the side walls of which form, respectively, a fixing surface and/or a sealing surface of the tank.

A very well functioning configuration is obtained, for example, if six convexities and six concavities are provided along a circular line that has a diameter of less than 3 cm.

The filter inlet of the filter cartridge may be formed on the outer side of the filter connection nipple as a ring-shaped mesh hole, whereby the filter cartridge is open in the water tank for the water contained therein.

The filter cartridge is improved by providing a guide structure inside the filter connection nipple to guide and receive the centering element located on the side of the water tank. Due to this, the filter cartridge can be oriented in the axial direction when installed in the corresponding water tank and fixed in this orientation in the operating position.

If the guide structure has at least one guide groove extending in the axial direction, i.e. parallel to the central axis, for receiving at least one guide rib of the centering element located on the side of the water reservoir, then due to this guide structure in interaction with the corresponding centering element located on the side of the water reservoir, the filter cartridge can be guided to at least one angular position due to axial movement when inserted into the water reservoir and additionally fixed there.

In order to provide guidance and fixation in several angular positions, the guide structure may have several guide grooves distributed around the perimeter.

The proper guidance of the filter cartridge to the desired angular position occurs when the wall of the guide grooves is rounded in such a way that the width of the groove narrows from the bottom up relative to the operating position. The guidance of the filter cartridge can be further improved by rounding the wall of the guide grooves in such a way that the width of the groove narrows radially from the inside out. In the combination of both of these tapering groove shapes, a kind of funnel effect is formed for the rib of the centering element, located on the side of the water reservoir, which enters such a groove.

The specified groove shapes can be formed, for example, by means of internal bends of the wall of the guide structure connecting the guide grooves.

The inventive shape of the filter sealing surface can also serve to improve the fixation of the filter cartridge by the fact that the filter sealing surface is simultaneously provided as a filter fixing surface. The inventive shape of the filter sealing surface, provided as a filter fixing surface, facilitates the deformation of the filter connection nipple in the region of the filter fixing surface, since the radial convexities and/or concavities form the shape of a ring spring, the perimeter of which can elastically expand or contract. Due to such a simplified deformation due to the varying radius, it is possible to improve the mechanical clamping and thus the fixation, for example, compared to a round or polygonal shape.

The elastic deformation capability of the filter fixing surface can be improved by the fact that the annular connecting nipple of the filter connecting element facing the filter fixing surface in the region of the filter fixing surface has an annular wall with an inner side and an outer side that run parallel to or inclined relative to each other. Depending on whether the connecting nipple is put on the fixing surface of the reservoir or inserted into it, either the outer or the inner surface of the annular wall includes the filter fixing surface or forms it.

Since in this configuration the side of the wall opposite the filter fixing surface has the same shape with a correspondingly larger or smaller perimeter, this wall is designed as a whole as a ring spring. Thus, the ring wall forms a ring spring with peripheral sides parallel or inclined relative to each other.

In addition, the annular connecting nipple of the filter connecting element can have an outer and/or inner wall that is beveled relative to the vertical, so that the outer wall and the inner wall converge from top to bottom relative to the operating position of the filter cartridge. This forms a guiding aid that facilitates the insertion of the connecting nipple into the gap between two surfaces molded to fit each other and located on the tank side, wherein the surfaces located on the tank side can form at least partially the inner and/or outer sealing surface of the tank.

Accordingly, the beveled outer wall may have an outer filter sealing surface and/or the beveled inner wall may have an inner filter sealing surface in order to enter into a hermetically sealed connection with a corresponding sealing surface of the tank with a geometric lock.

In the water tank for the household appliance corresponding to the above-described filter cartridge, there is a tank bottom, wherein the tank bottom is provided with an annular sealing surface of the tank for hermetically sealing the filter cartridge, which covers the through hole of the tank for the passage of water from the filter cartridge through the wall of the tank bottom into the household appliance. For effective interaction with the above-described sealing surface of the filter, the shape of the sealing surface of the tank along its perimeter has a varying radius relative to the central axis, so that the sealing surface of the tank has radial concavities and/or radial convexities.

This results in the above-described possibilities for coding the filter cartridge on the side of the water tank. Due to this shape of the sealing surface of the tank, a filter cartridge with a corresponding filter sealing surface can be used in the water tank, as described above. Thus, for the adaptation of the filter cartridge and the connection arranged on the side of the tank, the choice of materials and their arrangement can be decisive in view of this design and can therefore be a component of the coding. In this case, the presence of corners or ribs in the region of the sealing surfaces can be eliminated, as a result of which the sealing function is improved, for example, compared to the polygonal shapes of the known art. Due to the variable radius, it is also possible to improve the mechanical clamping and thus the fixation, for example, compared to the round shape.

The annular sealing surface of the tank and/or the annular sealing surface of the filter,

preferably, are designed with the possibility of radial sealing over their entire closed perimeter. In this way, continuous tightness of the corresponding sealing surface is achieved over the entire perimeter, wherein the size of the corresponding sealing surface along its axial extension is adaptable to the desired application.

The sealing surface of the tank is designed to correspond to the above-described sealing surface of the filter in such a way that the annular sealing surface of the tank forms an inner surface of the connecting element of the tank facing the central axis of the through opening of the tank. Such a sealing surface of the tank corresponds to the shape of the connecting nipple located on the side of the filter, so that it can be inserted into the connecting element of the tank. Despite the alternating bends along the perimeter, when inserting the connecting nipple of the filter into the connecting element of the tank with the sealing surface of the tank facing radially inward, the desired sealing effect should be achieved essentially along the entire perimeter.

For the use of a filter cartridge on which the convexities and/or concavities of the filter sealing surface, as described above, are designed with periodic oscillation around a circular line, the concavities and/or convexities of the sealing surface of the reservoir are also designed with periodic oscillation around a circular line, respectively, of the filter sealing surface. Likewise, for the purpose of matching the correspondingly designed filter sealing surface, the concavities and/or convexities of the filter sealing surface may have a rounded shape (stroke).

To match the appropriately formed sealing surface of the filter, the sides of the sealing surface of the tank may include six concavities and six convexities along a circular line with a diameter of less than 3 cm.

By means of the mentioned individual adaptations of the sealing surface of the tank to the correspondingly formed sealing surface of the filter, the advantages described above with respect to the filter cartridge can be achieved.

The annular connecting element of the tank may include an annular elastomer seal in which radial protrusions and/or radial concavities are pre-formed. Such a connecting element of the tank is particularly advantageously used, in particular, in combination with a filter cartridge, in which the annular connecting nipple of the filter in the region of the sealing surface of the filter consists of a polymer material that is stable in shape at the operating temperature. When the filter cartridge is inserted, the elastomer seal yields to the pressure of the polymer material that is stable in shape on the side of the filter cartridge.

Preferably, on the inner side of the radial convexities and/or radial concavities, the elastomer seal has a sealing surface of the reservoir, which performs sealing relative to the filter cartridge.

In addition, it is advantageous if the sealing surface of the elastomer seal reservoir has an inclined stroke (shape) leading from top to bottom toward the central axis. Due to this stroke, the elastomer seal is subjected to increasing elastic deformation outward during the insertion of the filter cartridge and, by means of the resulting return force, a pressing pressure is generated, ensuring the desired sealing effect.

By deforming the elastomer seal, in addition to the locking function and the sealing function, one or more additional functions can be performed. For example, this can be a hydraulic function, such as a valve function, etc.

From the point of view of the application of the elastomer seal, it is advantageous for the bottom of the tank to have a fastening ring and an elastomer seal inserted into the fastening ring. In this case, the outer fastening ring prevents the expansion of the elastomer seal, so that the elastic return force of the elastomer is almost entirely used to create the pressing pressure.

In order to prevent leakage between the retaining ring and the elastomer seal, the elastomer seal may have a sealing surface for hermetically sealing the elastomer seal relative to the retaining ring. In addition, the elastomer seal may have a sealing surface for hermetically sealing relative to the bottom of the tank.

Preferably, a bypass channel for unfiltered water may be provided in the bottom of the tank, which passes from the interior of the water tank through the fastening ring and the elastomer seal. This allows drainage from the water tank when the filter cartridge is missing. Such drainage may be required when there is no filter cartridge at hand, or operation without a filter cartridge is required, for example during maintenance, such as cleaning or descaling of the corresponding equipment. The cleaning or descaling agents used in such cases must not get into the filter cartridge.

The bypass channel may include, for example, an annular gap in the elastomer seal, allowing a distributed flow of water around the perimeter into the outlet pipeline.

Preferably, the elastomer seal includes a shut-off element by means of which the bypass channel can be closed, in particular by inserting a filter cartridge into the elastomer seal. As a result, when using a corresponding filter cartridge, the bypass channel can be closed without any further action.

The elastomer seal can be formed, for example, so that the shut-off element includes two opposing annular sealing surfaces in the annular gap, by means of which the annular gap can be closed when the elastomer seal is deformed. If the inner sealing surface of these two annular sealing surfaces expands when the filter cartridge is inserted into the elastomer seal, then a geometric locking with the outer annular sealing surface occurs, whereby the bypass channel is closed.

To facilitate securing the mounting ring and/or elastomeric seal to the bottom of the tank, the mounting ring may include a retainer for securing to the bottom of the tank.

In addition, a centering element for insertion into the filter cartridge can be provided at the bottom of the tank. By means of such a centering element, guidance can be provided when inserting the cartridge into the correct operating position. In addition, by means of the centering element, additional coding is provided by giving it a corresponding shape, in order to ensure that only the correct filter cartridge is installed. In addition, the centering element can also perform a locking function, for example against twisting or tilting of the filter cartridge. Unintentional separation of the filter cartridge can be prevented by means of corresponding friction surfaces, so that when removing the filter cartridge, a corresponding frictional force must be overcome. Additional locking elements can be located on the centering element.

To connect the centering element to the elastomer seal, the centering element may have a support plate located in the receiving element of the elastomer seal and enveloping it at the rear along the edge. Due to this, the centering element is fixed to the bottom of the tank by means of the elastomer seal.

If a bypass for unfiltered water is provided, the centering element may have a bypass hole, for example in the support plate, which is open to the central drain.

Preferably, the centering element includes a centering pin projecting upward from the support plate of the centering element and having an annular outer surface that has a varying radius relative to the central axis, so that the outer surface has radial convexities and/or radial concavities. Such a centering pin is adjusted to the outer contour of the elastomer seal and the filter connecting nipple of the corresponding filter cartridge.

In one preferred embodiment of the invention, the concavities and/or convexities of the outer surface of the centering pin are designed with a periodic oscillation around a circular line. This design corresponds to the shape of the corresponding elastomer seal and thus leaves only the annular gap with the concavities and/or convexities free for inserting a suitable filter cartridge. With this design, the use of otherwise shaped connecting elements inside the elastomer seal is also prevented and the coding function is thus improved. In addition, on the inside of the filter connection nipple along its convexities and/or concavities, the filter connection nipple can be supported in order to reliably deform the elastomer seal on the opposite outer side when inserting the filter cartridge.

The concavities and/or convexities of the outer surface of the centering pin may have a rounded shape in order to match the shape of the elastomer seal and/or the filter connecting nipple.

With the appropriate shape of the elastomer seal and/or the filter connecting nipple, in order to adjust the centering pin, six concavities and six convexities are provided in its outer surface along a circular line with a diameter of less than 3 cm.

In one of the preferred embodiments of the invention, above the outer surface with concavities and/or convexities, a step and a protrusion located with an inward offset are provided, which further enters the filter cartridge and, thus, has a greater axial guide length.

To prevent axial compaction at this stage due to an unsuitable filter cartridge, at least one tooth protruding upward in continuation of the peripheral surface may be located above the annular outer surface.

Above the annular outer surface in the centering element, at least one through hole leading to the through opening of the reservoir can be provided, which connects the water inlet into the filter cartridge with the water outlet and which is closed only by the filter cartridge sealing according to the invention.

The axial direction and centering can be improved by providing at least one guide rib in the centering element above the annular wall. Water can flow next to this rib or, in the case of several guide ribs, between them. These guide ribs can be guided in the guide grooves described above when the filter cartridge is put on.

Another guiding aid for the centered insertion of the filter cartridge is provided by the fact that the guide rib or guide ribs on the upper side are beveled toward the central axis. The filter connection nipple, when inserted, can slide along the aforementioned bevels until it occupies a centered position.

The elastomer seal may also have a sealing surface to seal the mounting ring against the bottom of the tank to ensure that unwanted water from the water tank does not leak through the mounting ring past the filter cartridge.

In addition, the fastening ring can be provided with a lock for fixing the fastening ring to the embedded part or to the bottom of the tank. This simplifies the installation of the fastening ring. If the centering element, as described above, is also fixed with a fastening ring, then its installation is simplified and, under certain conditions, also the installation of the water tank valve located underneath it.

The execution of the water tank is simplified if a bottom-mounted embedded part is provided on the bottom of the tank, which includes parts intended for connecting the filter cartridge from the side of the water tank. With the help of the embedded part, different connecting structures can be easily created with the same execution of the water tank, due to the fact that different embedded parts are used. In addition, different requirements can be selected with respect to the processing tolerance of the water tank and the corresponding embedded part.

In this case, such an embedded part can preferably include an elastomer seal and/or a fastening ring and/or a centering element and/or at least partially a bypass channel. All essential connecting structures of the reservoir can be provided on the embedded part, so that the adaptation of the water reservoir to specific filter cartridges can be carried out only by selecting a suitable embedded part.

Examples of the invention are shown in the drawings and are further explained in more detail with reference to the figures. Shown:

Fig. 1 - perspective view of the bottom of the tank with a filter cartridge installed according to the known prior art,

Fig. 2 - exploded perspective view of the bottom of the tank with a centering element and a fastening ring,

Fig. 3 - perspective view of the bottom of the tank according to Fig. 2 with the installed centering element and the installed fastening ring,

Fig. 4 - top view of the bottom of the tank according to Figs. 2 and 3,

Fig. 5 - perspective view of the connecting area of the filter cartridge when viewed from the side,

Fig. 6 - perspective view of the connecting area of the filter cartridge when viewed diagonally from below,

Fig. 7 - perspective view of the cut-off height of the connecting nipple of the filter cartridge inserted into the bottom of the tank,

Fig. 8 - perspective view of a filter cartridge cut at the height of the guide grooves, inserted into the bottom of the tank,

Fig. 9 - perspective view of the filter cartridge inserted into the bottom of the tank,

Fig. 10 - perspective view of the centering element,

Fig. 11 - sectional view of the bottom of the tank without a filter cartridge with the water tank valve open,

Fig. 11a and b are two enlarged fragments from Fig. 11 to illustrate the closable bypass channel in the tank seal,

Fig. 12 - sectional view of the bottom of the tank according to Fig. 11 with the filter cartridge inserted,

Fig. 12a is an enlarged fragment from Fig. 12 to illustrate the closed bypass channel,

Fig. 13 - schematic front view of a filter connection fitting according to the invention,

Fig. 13a is an enlarged fragment from Fig. 13, and

Fig. 14 is a fragment showing the connecting area of the filter cartridge, for explaining the guiding auxiliary means formed by the bevels of the connecting nipple.

Fig. 1 shows a conventional design of a water tank 1 of a beverage preparation machine, such as a coffee machine, for example a coffee machine according to the state of the art. The water tank 1 includes a tank bottom 2 and side walls 3 of the water tank, partially shown in dashed lines. A filter cartridge 4 with a filter housing 5 is mounted in the water tank 1. The connection between the tank bottom 2 and the filter cartridge 4 is ensured by means of a tank connecting element 6 on the side of the water tank and a filter connecting element 7 located on the filter side.

The filter cartridge 4 is located in the internal space 8 of the water reservoir 1, i.e., during operation of the device it is completely or partially in the water stored in the water reservoir 1. From the lower side of the water reservoir 1 there protrudes a connecting nipple 9 of the filter of the water reservoir 1 for connecting the water reservoir 1 to a not shown machine for preparing beverages.

Fig. 2 shows a circular cutout of the bottom 2 of the tank, wherein there is a fastening ring 10 and a centering element 11 for insertion into a recess 12 of the bottom 2 of the tank. Fig. 2 also shows the body 13 of the tank valve with a seal 14 made in the form of a ring of circular cross-section, from which two rods 15 protrude upward. The fastening ring 10 carries an elastomer seal 16.

In Fig. 3 and 4, the fastening ring 10 and the centering element 11 are shown installed in the bottom 2 of the tank. It can be seen that the rods 15 can pass through the centering element and thus represent a coding element for coding the water tank relative to the corresponding connecting element of the machine, which, when the water tank is inserted, is to activate the valve body 13 of the tank. In addition, in Fig. 4 it can be clearly seen that the elastomer seal 16, which forms the seal 17 of the tank, is an annular seal, which has a variable radius R along its periphery with respect to the central axis A, so that the inner surface of the seal 17 of the tank, which forms the sealing surface 18 of the tank, has radial concavities 19 and radial convexities 20. The first sealing surface 18 of the tank is designed with the possibility of radial sealing along its entire closed perimeter and at the same time is the locking surface of the tank.

Fig. 5 shows a connecting area 21 of a suitable filter cartridge 22. The connecting nipple 23 of the filter forms an inner ring surrounded by an outer ring 24 with axially extending projections 25 and depressions 26. Between the inner ring 23 and the outer ring 24 there is an annular mesh opening 27 (mesh inlet) through which water enters the filter cartridge. The outer surface 28 and the inner surface 68 of the connecting nipple 23 of the filter are provided with convexities 29 and concavities 30 suitable for the sealing surface 18 of the reservoir. The outer surface forms, over a certain axial extent, at least partially, a sealing surface 28 of the filter, designed with the possibility of radial sealing along its entire closed periphery. The outer surface, in particular in its region designed as a sealing surface 28 of the filter, and/or the inner surface 68 of the connecting nipple 23 of the filter can simultaneously perform at least partially the function of a fixing surface of the filter.

In the view shown in Fig. 6, in addition to the above-described parts of the connecting region 21 of the filter cartridge 22, the configuration of the guide structure 31 of the filter cartridge 22 for receiving the centering element 11 is shown. The guide structure has guide grooves 32 located coaxially with the faces 33 of the polyhedral ring 34, in this case, for example, six guide grooves coaxial with the six faces of the ring in the form of a hexagon. In the sectional image shown in Fig. 7, when viewed from above, the plane of the section passes through the polyhedral ring 34.

The inner bends 35, lying between the edges 33 and the guide grooves 32, enter upwards into the inner space of the filter cartridge. The inner bends 35 form the side walls 3 6 of the guide grooves 32. Due to the curved shape of the walls 36 of the guide grooves 32, they narrow both in the axial direction upwards (relative to the operating position) and in the radial direction from the inside out. In the cross-sectional image shown in Fig. 8, viewed from above, the plane of the section passes at a height at which the guide grooves 32 are already clearly formed. A pressure line adjoins the inner space in the center, along which the water entering the filter cartridge 22 is directed upwards to the filtration section.

In Fig. 9 the filter cartridge 22 is shown as a whole. In the filter housing 37 there is an optional lateral metering opening 38 and the described bottom-side water connection. The optional metering opening 38 is provided only in the case of a filter cartridge which is designed to introduce additives, such as minerals, vitamins, etc., into the water supply from a metering chamber provided in the filter housing 37. Since such a metering chamber is closed within the filter housing 37 with respect to the filtration section, this aspect is not significant from the point of view of filtration. The filter cartridge according to the invention can also be designed simply without a metering chamber and a corresponding metering opening 38. In Fig. 9, in particular, the operating position can be seen, to which the information given above and below in this description refers.

Fig. 10 shows a perspective view of the centering element 11. The centering element is provided with a support plate 39, which in the mounted state, being located in the receiving element of the elastomer seal, embraces it from behind along the edge. From the support plate 39, a centering pin 40 projects upwards, having an annular outer surface 41, which forms a second fixing surface of the reservoir. The outer surface 41 has a varying radius along its perimeter relative to the central axis A, so that the outer surface 41 also has radial concavities 42 and convexities 43. Consequently, the outer surface 41 is adjusted to the corresponding shape of the connecting nipple 9 of the filter.

For further adjustment, the concavities 42 and convexities 43 of the outer surface 41 are also made with periodic oscillation around a circular line and have a rounded shape. In the illustrated embodiment, in accordance with the presented embodiment of the filter cartridge 22, six concavities 42 and six convexities 43 are provided along a circular line with a diameter of less than 3 cm. In the case of another filter cartridge, the adjustment of the outer surface 41, respectively, the second fixing surface of the reservoir should be changed accordingly.

All adjustments of the outer surface 41 of the centering pin 11 result in the fact that in the mounted state only the annular gap between the outer surface 41 and the elastomer seal 16 is open for the introduction of the filter connection nipple 23. As a result, additional coding is achieved against the use of an unsuitable filter cartridge. In addition, it is thus possible to support the filter connection nipple 23 on its inner side with the outer surface 41 of the centering pin 11. Consequently, the pressing pressure of the filter connection nipple on the elastomer seal 16 along the changing shape over the entire shape of the periphery can be uniformly increased.

Above the annular outer surface there is at least one upwardly projecting tooth 44. The mentioned one or more teeth 44 are formed on the step 45 of the centering pin 40. In addition, the elevations 46, following the shape of the outer surface 41, relative to the step 45 are arranged at a certain distance from the teeth 44, so that between the teeth and the elevations 46 there remains a free space 47. The tooth or teeth 44 and/or the elevations 46 can prevent the use of an axial seal in violation of the coding. Above the outer surface 41 there is also a through hole 48, which in the mounted state of the centering element 11 leads to the through hole of the reservoir. Through the through hole 48, the filtered water of the filter cartridge 22 can be drained from the water reservoir.

In the support plate 39 under the outer surface 41 there are one or more through bottom openings 49. Unfiltered water can be removed from the water reservoir through these bottom openings. Under the elevations 4 6 and inside the wall supporting the outer surface 41 there is a hollow space 50 for receiving the body 13 of the reservoir valve.

Above the annular outer surface 41 there are guide ribs 51 which, as in the illustrated embodiment, can be chamfered on their upper side. The guide chamfers 52 formed in this way facilitate the insertion of the guide ribs 51 into the guide grooves 32 of the filter cartridge 22. In the sectional view according to Fig. 4, the guide chamfers 52 of the guide ribs 51 in the mounted filter cartridge 22 are clearly visible.

In Fig. 11, 11a, 11b, 12 and 12a, assembled parts of the water tank 1 for attaching the filter cartridge are shown without the filter cartridge 22 and with the filter cartridge 22. The fastening ring 10 is provided with a locking protrusion 53, which ensures its fixation on the bottom 2 of the tank due to the fact that it embraces the rib 54 of the bottom of the water tank from behind. The elastomer seal 16 has a bottom section 55, which embraces the fastening ring 10 from below and thus holds the elastomer seal 16 with the fastening ring 10 on the bottom 2 of the tank.

The elastomer seal 16 has a sealing surface intended for sealing relative to the bottom 2 of the tank and implemented in this case as a sealing thickening 56. For hermetically sealing the elastomer seal 16 relative to the fastening ring 10, the enveloping sealing surface can be provided in different places. In the presented exemplary embodiment, an annular seal 57 is provided molded at the top of the elastomer seal 16, which in the sealing groove 58 of the fastening ring ensures sealing with it.

The elastomer seal 16 includes an outer ring 59 and an inner ring 60, connected and made as a single unit with each other. The outer ring 59 and the inner ring 60 both follow in their shape along the perimeter the variable radius of the fastening ring 10, the connecting nipple 23 of the filter and the elastomer seal 16 and the concavities and convexities formed by them. The outer ring 59 is stepped and carries an annular seal 57 and a sealing bead 56. The outer ring 59 is also provided with one or more bypass openings 61, through which unfiltered water in the direction of flow P1 can flow into the annular gap 62 between the outer ring 59 and the inner ring 60. The bypass opening 61 of the elastomer seal 16 in the mounted state is located directly after the bypass opening 63 in the fastening ring 11, which (opening) can be seen, for example, also in Fig. 1 and 3. Through the bypass opening 63, unfiltered water can flow in the direction P2 from the annular gap 62 from the water reservoir 1 into the corresponding beverage preparation machine.

On the lower side of the inner ring 60 there is a working lip 64 of the seal, lying opposite the sealing surface 65 of the outer ring 59. In the unstressed state of the elastomer seal 16, the annular gap 62 between the outer ring 59 and the inner ring 60 is open from below, as shown in Fig. 11, so that unfiltered water directed 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, forming the seal 17 of the water reservoir, is beveled downwardly inwardly. This shape of the bypass is clearly shown in the enlarged images of Fig. 11a and b.

When the filter cartridge with the filter connection nipple 23 is inserted, the elastomer seal 16 is deformed so that the inner side 66 is pressed outward and extends essentially vertically along the filter connection nipple. In this case, the sealing edge 64 is pressed against the opposite sealing surface 65 and thus closes the annular gap 62 and, consequently, the bypass through the bypass openings 61, 63. When deformed, a pressing pressure is generated, which ensures that the sealing surface 17 of the reservoir is pressed against the sealing surface 28 of the filter and, at the same time, the sealing edge 64 is pressed against the sealing surface 65. This state is shown in Fig. 12 and Fig. 12a.

In Fig. 11 and Fig. 12, the body 13 of the reservoir valve is raised by a stop of the corresponding machine, not shown in detail, towards the return spring 67 in the hollow space 50 and is in the open state, which occurs when the water reservoir is inserted. When the water reservoir is removed, the body 13 of the reservoir valve closes under the action of the return spring 67.

The sealing surface 18 of the reservoir is formed by the inner side 66 of the elastomer seal and is at the same time the first fixing surface 18 of the reservoir. As already described above, in the inserted state of the filter cartridge 5, 22, the first fixing surface 28 of the filter, formed by the sealing surface 28 of the filter, adjoins this side under the action of the pressing pressure, which deforms the elastomer seal 16 in such a way that a fixing and sealing geometric closure occurs.

In this case, a second filter fixing surface 68 (see Fig. 5) is adjacent to the outer surface 41 forming the second filter fixing surface, which is formed by the inner surface of the filter connection nipple 23. Such a geometric closure is also formed by the action of the pressing pressure. According to the shape of the filter connection nipple 23 according to the invention, it forms an annular wall, which, if necessary, can be elastically stretched. As a result, it is possible to compensate for the permissible deviations with good fixation, which is created by means of a corresponding tension. Due to the parallel or inclined relative to each other formation of the first fixing surface 28 and the second fixing surface 68, the annular wavy wall of the connection nipple 23 lying between them forms a wavy annular spring 70. The second filter fixing surface 68 can also act as a second sealing surface of the filter.

The filter connection nipple corresponding to the front view shown in Fig. 13 and the enlarged fragment shown in Fig. 13a has the described wave-like shape with convexities 29 and concavities 30. The annular wall of the filter connection nipple 23 with a thickness W has a first filter fixing surface 28 on the outer side 71 and has a second filter fixing surface 68 on the inner side 72. The outer side 71 and the inner side 72 of the wall are parallel in the shown view, but are inclined to each other in the axial direction, which is further explained below. The wave-like shape is clearly shown by the dashed middle line 73.

The middle line 73 passes in a wave-like manner between the outer enveloping circle 74, the radius of which has the largest value of the varying radius, and the inner enveloping circle 75, the radius of which has the smallest value of the varying radius of the wave form. The convexities 29 and concavities 30 of the middle 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 illustrated embodiment, all circular segments 76, 77 have the same segment radius S. The midpoints 78, 79 of the circular segments 76, 77 in the case of convex circular segments 76 lie inside the inner enveloping circle 75, and in the case of concave circular segments 77 lie outside the outer enveloping circle 74. The convex circular segments 76 and the concave circular segments 77 transition into each other tangentially and are uniformly distributed around the circumference, so that a rotationally symmetrical shape is formed. In the illustrated embodiment, there are six convex circular segments 76 and six concave circular segments 77, alternating with an angular step of 30°, i.e. the convex circular segments 76, like the concave circular segments 77, are spaced from each other at an angle of 60°.

By means of the selection of the radius of the segments and the resulting position of the corresponding middle points 78, 79, the middle line runs comparatively gently curved, wavy around the middle circular line 80. The middle line 73 intersects the middle circular line 80 at an obtuse angle p. Due to this, the length of the arc of the convexities 29 is significantly greater than the length of the arc of the concavities 30, as a result of which the angle y described by the arc of the segment of convexities 29 is significantly greater than the angle 5 described by the concavities 30. Due to this shape, the elastic (spring) action of the connecting nipple 23 of the filter is improved.

For comparison, a drawing of a circular segment 81 is also presented, the midpoint of which lies directly on the midline 73. This move, not implemented in this embodiment, has significantly smaller segment radii and an essentially perpendicular move relative to the midline 73.

A good elastic action was achieved with radii and wall thicknesses in which the radius of the inner enveloping circle 75 is from 5% to 15% of the radius of the outer enveloping circle 74, and the radius of the convex and/or concave circular segments is from 20% to 35% of the radius of the outer enveloping circle 74. The thickness W of the wall between the outer side 71 of the wall and (relative to the operating position) the inner side 72 of the wall parallel or inclined relative to it is preferably from 5% to 15% of the radius of the outer enveloping circle 74.

The presented example is characterized by the radius of the outer enveloping circle 7 4 of about 11 mm and the radius of the inner enveloping circle 75 of about 9.75 mm. In this case, the radius of the convex and concave circular segments is 3.08 mm, and the wall thickness between the outer side 71 of the wall and the inner side 72 of the wall parallel or inclined relative to it is about 0.9 mm.

As shown in Fig. 14, the outer 71 and/or inner 72 wall of the filter connection nipple 23, which, depending on the embodiment, also form one or two sealing surfaces 28 of the filter, are beveled relative to the vertical at an angle ω1 or ω2, so that they converge from top to bottom relative to the operating position of the filter cartridge 4, 22. Such a bevel or bevels at an angle ω1 and/or ω2 form an input aid for introducing the connection nipple 23 into the annular gap between the elastomer seal 16 and the outer surface 41 of the water reservoir 1.

List of reference positions:

1 Water tank

2 Bottom of the water tank

3 Side wall of the water tank

4 Filter cartridge

5 Filter housing

6 Tank connecting element

7 Filter connecting element

8 Interior space

9 Filter connection nipple

10 Fastening ring

11 Centering element

12 Deepening

13 Tank valve body

14 Seal

15 Rod

16 Elastomeric seal

17 Water tank seal/O-ring

18 Sealing surface of the tank

19 Concavity 2 0 Convexity

21 Connecting area

22 Filter cartridge

23 Filter connection nipple/inner ring 2 4 Outer ring

25 Protrusion 2 6 Recess

27 Mesh hole

28 Filter sealing surface/outer surface

29 Bulge

30 Concavity

31 Guide structure

32 Guide groove

33 Edge

34 Polyhedral Ring

35 Inner bend

36 Wall

37 Filter housing

38 Metering hole

39 Support plate

40 Centering pin

41 Outer surface

42 Concavity 4 3 Convexity 4 4 Tooth

45 Step

46 Rise

47 Free space

48 Through hole

49 Through hole in the bottom

50 Hollow space

51 Guide rib

52 Guide bevel

53 Locking lug

54 Bottom rib

55 Bottom section

56 Sealing thickening

57 O-ring seal

58 Sealing groove 5 9 Inner ring

60 Outer ring

61 Bypass hole

62 Annular gap

63 Bypass hole

64 Working lip of the seal

65 Sealing surface

66 Inner side

67 Return spring

68 Second fixing surface/inner surface 7 0 Ring spring

71 Outer side of the wall

72 Inner side of the wall

73 Middle line

74 Outer Envelope Circle

75 Inner Envelope Circle

76 Convex circular segment

77 Concave circular segment

78 Midpoint

79 Midpoint

80 Middle Circle Line

81 Circular Segment

84 Through hole of the tank

A Axis

W Wall thickness

S Segment radius

P1 Flow direction

P2 Flow direction.

Claims (46)

1. A water tank (1) for a household appliance with a connection for a filter cartridge (22), wherein on the bottom of the tank there is an annular sealing surface of the tank for hermetically sealing the filter cartridge (22), and this sealing surface of the tank surrounds a through hole of the tank intended for water to flow from the filter cartridge (22) through the wall of the bottom of the tank to the household appliance, characterized in that the sealing surface (18) of the tank along its periphery has a varying radius relative to the central axis, so that this sealing surface (18) of the tank has radial concavities (19) and/or radial convexities (20), wherein the convexities (20) and/or concavities (19) have a rounded shape. 2. A water reservoir (1) according to claim 1, characterized in that the water reservoir (1) has a filter cartridge (22) which is provided with a filter housing (37), the wall of which waterproofly separates the inner side of the housing from the outer side of the housing, and a filter inlet opening is provided, located in the operating position of the filter cartridge (4) at its lower end region and open with respect to the external environment of the filter housing (5), and relative to the flow direction during operation, after the filter inlet opening, a device is provided for feeding water into the filter housing (37), which includes at least one filter chamber having at least one filter medium and which ends in the filter outlet opening for draining water from the filter cartridge (22), and wherein a filter connecting element is provided with an annular connecting nipple (23) having an annular sealing surface (28) of the filter for hermetically connecting the filter cartridge (22) to the sealing surface of the reservoir in the water tank, wherein the shape of the sealing surface (28) of the filter along the periphery of the annular connecting nipple (23) of the filter has a varying radius relative to the central axis, so that the sealing surface (28) of the filter has radial convexities (29) and/or radial concavities (30), wherein the convexities (29) and/or concavities (30) have a rounded shape. 3. A water reservoir (1) according to claim 1 or 2, characterized in that the annular sealing surface (18) of the reservoir and/or the annular sealing surface (28) of the filter are designed with the possibility of radial sealing along their entire closed perimeter. 4. A water reservoir (1) according to claim 2 or 3, characterized in that the annular connecting nipple (23) of the filter connecting element, having a sealing surface (28) of the filter, at least in the area of the sealing surface (28) of the filter, is made of a polymeric material characterized by shape stability at the operating temperature, which, in particular, is more rigid than an elastomer. 5. A water reservoir (1) according to one of paragraphs 2-4, characterized in that the sealing surface (28) of the filter forms the outer surface of the annular connecting nipple (23) of the connecting element of the filter facing away from the central axis (A) of the outlet opening of the filter. 6. A water reservoir (1) according to one of paragraphs 2-5, characterized in that the arrangement of the convexities (29) and concavities (30) of the sealing surface (28) of the filter is formed rotationally symmetrically along the perimeter. 7. A water reservoir (1) according to one of paragraphs 2-6, characterized in that the convexities (29) and/or concavities (30) are made with periodic oscillation around a circular line. 8. A water reservoir (1) according to one of paragraphs 2-7, characterized in that the arrangement of the convexities (29) and concavities (30) of the sealing surface (28) of the filter is made with the same angles along the perimeter. 9. A water reservoir (1) according to one of paragraphs 2-8, characterized in that the convexities (29) and/or concavities (30) have a rounded shape. 10. A water reservoir (1) according to one of paragraphs 2-9, characterized in that along the circular line there are six convexities (29) and six concavities (30), which have a diameter of less than 3 cm. 11. A water reservoir (1) according to one of paragraphs 2-10, characterized in that a guide structure is provided inside the connecting nipple (23) of the filter for guiding and receiving the centering element (11) located on the side of the reservoir. 12. A water reservoir (1) according to claim 11, characterized in that the guide structure (31) has at least one guide groove (32) for receiving at least one guide rib (51) of the said centering element (11) located on the side of the reservoir. 13. A water reservoir (1) according to claim 11 or 12, characterized in that the guide structure (31) has guide grooves (32) distributed around the perimeter. 14. A water tank (1) according to claim 13, characterized in that the wall of the guide grooves (32) is rounded in such a way that, relative to the operating position, the width of the groove narrows from bottom to top. 15. A water reservoir (1) according to claim 13 or 14, characterized in that the wall of the guide grooves (32) is rounded in such a way that the width of the groove narrows from the inside out. 16. A water reservoir (1) according to claim 14 or 15, characterized in that the tapering shape of the guide grooves is formed as an internal bend (35) in the wall (36) connecting the guide grooves. 17. A water reservoir (1) according to one of paragraphs 2-16, characterized in that the said inlet opening of the filter cartridge filter is designed as an annular mesh opening (27). 18. A water reservoir (1) according to one of claims 2-17, characterized in that the annular connecting nipple (23) of the filter connecting element, having a sealing surface (28) of the filter, at least in the area of the sealing surface (28) of the filter, has a wall with an outer side (71) of the wall that runs parallel to or inclined relative to the inner side (72) of the wall and that includes or forms the sealing surface (28) of the filter. 19. A water reservoir (1) according to one of paragraphs 2-18, characterized in that the annular connecting nipple (23) of the filter connecting element has an outer (71) and/or inner (72) wall, which, in relation to the operating position of the filter cartridge, are beveled relative to the vertical by an angle ω1 and/or ω2, so that the outer wall (71) and the inner wall (72) of the filter cartridge converge from top to bottom. 20. A water tank (1) according to claim 18 or 19, characterized in that the beveled outer wall (71) has an outer sealing surface (28) of the filter and/or the beveled inner wall (72) has an inner sealing surface of the filter. 21. A water tank (1) according to one of the preceding claims, characterized in that the sealing surface (18) of the tank forms an internal surface of the annular connecting element of the tank facing the central axis of the through opening of the tank. 22. A water reservoir (1) according to one of the preceding claims, characterized in that the concavities (19) and/or convexities (20) are made with periodic oscillation around a circular line. 23. A water reservoir (1) according to one of the preceding claims, characterized in that along the circular line there are six concavities (19) and six convexities (20) with a diameter of less than 3 cm. 24. A water tank (1) according to one of the preceding claims, characterized in that the annular connecting element of the tank includes an annular elastomer seal (16) in which radial protrusions (19) and/or radial concavities (20) are pre-formed. 25. A water tank (1) according to claim 24, characterized in that on the inner side of the radial convexities (19) and/or radial concavities (20) of the elastomer seal (16) there is a sealing surface (18) of the tank. 26. A water tank (1) according to one of the preceding claims, characterized in that the sealing surface (18) of the tank has a beveled shape, converging from top to bottom towards the central axis (A). 27. A water tank (1) according to one of the preceding claims, characterized in that the bottom (2) of the tank is provided with a fastening ring (10) and an elastomer seal (16) inserted into the fastening ring (10). 28. A water tank (1) according to one of paragraphs 24-27, characterized in that the elastomer seal (16) has a sealing surface (57) for hermetically sealing the elastomer seal (16) relative to the fastening ring (10). 29. A water tank (1) according to one of paragraphs 24-28, characterized in that the elastomer seal (16) has a sealing surface (56) for hermetically sealing the fastening ring (10) relative to the bottom (2) of the tank. 30. A water tank (1) according to one of the preceding claims, characterized in that a bypass channel for unfiltered water from the water tank is provided in the bottom of the water tank (1), passing from the internal space of the water tank through a fastening ring and an elastomer seal. 31. A water reservoir (1) according to claim 30, characterized in that the bypass channel includes an annular gap (62) in the elastomer seal (16). 32. A water reservoir (1) according to one of paragraphs 24-31, characterized in that the elastomer seal (16) includes a shut-off element, by means of which the possibility of closing the bypass channel is ensured. 33. A water reservoir (1) according to claim 32, characterized in that the shut-off element includes two opposing annular sealing surfaces (64, 65) in the annular gap (62), by means of which the possibility of closing the annular gap (62) is ensured by deformation of the elastomer seal (16). 34. A water tank (1) according to one of paragraphs 27-33, characterized in that the clamping ring (10) includes a retainer (53) for fixing the fastening ring (10) to the bottom (2) of the tank. 35. A water reservoir (1) according to one of the preceding claims, characterized in that a centering element (11) is provided at the bottom of the reservoir for insertion into a filter cartridge (22). 36. A water tank (1) according to claim 35, characterized in that the centering element (11) has a support plate (39) lying in the receiving element of the elastomer seal (16) and encircling it from behind along the edge. 37. A water reservoir (1) according to claim 36, characterized in that a centering pin (40) protrudes upward from the support plate (39) of the centering element (11), having an annular outer surface (41) which has a varying radius relative to the central axis (A), so that the outer surface (41) includes radial convexities (42) and/or radial concavities (43). 38. A water reservoir (1) according to claim 37, characterized in that the concavities (42) and/or convexities (43) of the outer surface (41) of the centering pin (40) are made with periodic oscillation around a circular line. 39. A water reservoir (1) according to claim 37 or 38, characterized in that the concavities (42) and/or convexities (43) of the outer surface (41) of the centering pin (40) have a rounded shape. 40. A water reservoir (1) according to one of paragraphs 37-39, characterized in that the outer surface (41) of the centering pin (40) is provided with six concavities (42) and six convexities (43) along a circular line with a diameter of less than 3 cm. 41. A water reservoir (1) according to one of paragraphs 37-40, characterized in that at least one upwardly protruding tooth (44) is located above the annular outer surface (41). 42. A water reservoir (1) according to one of paragraphs 37-41, characterized in that at least one through hole (48) is provided above the annular outer surface (41) in the centering element (11), leading to the through hole of the reservoir. 43. A water reservoir (1) according to one of paragraphs 37-42, characterized in that above the wall bearing the annular outer surface (41), at least one guide rib (51) is provided in the centering element (11). 44. A water tank (1) according to claim 43, characterized in that the guide rib (51) or guide ribs (51) on the upper side are beveled toward the central axis. 45. A water tank (1) according to one of the preceding claims, characterized in that a bottom-mounted part belonging to the bottom of the tank is provided on the bottom of the tank, which includes parts provided on the side of the tank for attaching a filter cartridge (22). 46. A filter cartridge for a water reservoir according to one of the preceding paragraphs, characterized in that it is made in accordance with one of paragraphs 2-19.