RU2812010C1 - Filter cartridge - Google Patents

Abstract

FIELD: filter cartridge.

SUBSTANCE: filter cartridge has a filter housing, the wall of which separates the inner side of the housing from the outer side of the housing, and a filter inlet opening is provided that is open during operation of the filter cartridge relative to the enveloping medium around the filter housing. Downstream of the filter, with respect to the direction of flow in operation, there is a device for supplying water into the filter body, which has at least one filter chamber provided with at least one filter medium, and which ends in a filter outlet for draining water from the filter cartridge. The filter-connecting element with a ring-shaped connecting fitting has a ring-shaped fixing surface of the filter for sealing the connection of the filter cartridge with the fixing surface of the water reservoir. The shape of the fixing surface along the circumference of the annular connecting piece has a variable radius relative to the central axis, so that the fixing surface of the filter has radial convexities and/or radial concavities having a rounded shape. Convexities and concavities form a wavy curve along a circle line, consisting of alternating convex circular segments and concave circular segments.

EFFECT: reliability of fixation and sealing of the cartridge increases and functionality expands.

17 cl, 18 dwg

Description

The invention relates to a filter cartridge according to the restrictive part of claim 1 of the formula.

Household appliances that provide water and are equipped with a water reservoir, in particular beverage preparation machines such as coffee makers, tea makers, etc., usually have filter cartridges to improve the quality of water in accordance with the intended purpose. These filter cartridges often use filter media to soften the water, such as ion exchange resin, or to improve taste, such as activated carbon. In combination with filter media, the dosed introduction of additives is also provided, for example, those that are beneficial to health or improve taste, for example, the addition of minerals or vitamins, etc.

The water tanks of such prior art machines are usually provided with connecting members located at the bottom of the tank with an annular sealing surface for sealing connection with the filter cartridge connecting element provided in the water tank, which surrounds a through hole in the bottom of the tank allowing water to flow from the filter cartridge and the water tank. tank into a household device.

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

To prevent the use of inappropriate filter cartridges, the connecting elements of the tank are equipped 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 documents 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 seals and sealing surface of the tank, thus, the seal itself, in addition to the sealing function, performs an additional codification function and a fixation function.

The disadvantage of these embodiments is that due to the angular contour, the locking at the corners is weakened, and it is difficult to ensure a seal when mating with a circular contour.

Thus, the object of the invention is to improve such a filter cartridge in such a way as to eliminate these disadvantages and improve the fixation of the filter cartridge.

This problem is solved in relation to the filter cartridge according to the restrictive part of claim 1 of the claims by means of characterizing features.

Further, the elements related to the water reservoir have a “reservoir” end component in their name, and the elements related to the filter cartridge have a “filter” end component in their name. Features of the preferred embodiments and improved embodiments of the invention are further described in such a way that their presence is not required, but they may occur.

The filter cartridge according to the invention has a filter housing, the wall of which separates the inner side of the housing from the outer side of the housing, wherein the open inlet of the filter, designed to receive water from a water source, does not have an additional connecting element, which, accordingly, when installed in a water tank in in working position would connect the filter cartridge with the internal space of the tank. Downstream of the filter inlet with respect to the direction of flow during operation, there is a device for supplying water to the interior of the filter housing, which includes at least one filter chamber provided with at least one filter medium, and ends with a filter outlet for discharging water. from the filter cartridge. The filter connecting member is provided with a ring-shaped connecting fitting having a ring-shaped filter fixing surface for fixing to the fixing surface on the water tank side.

The described design of the filter cartridge differs from the design of filter cartridges of devices, the housing of which provides a sealed connection to the water supply and is thus built into the water supply network.

The filter cartridge according to the invention has a filter fixing surface, the shape of which along the circumference of the annular filter connecting piece is characterized by a variable radius relative to the central axis, thus the filter fixing surface has radial convexities and/or radial concavities, while the convexities and/or concavities have a rounded shape , so there are no corners or edges.

Thanks to this, the fixation function will be improved and additional codification possibilities will appear. This shape of the filter fixing surface is combined with the corresponding fixing surface of the tank, and due to the presence of variable curvature of convexes or concavities along the circumference along the circumference, the connection with a hermetically sealed closure on or inside the contact surface of the tank in case of shape mismatch is complicated or completely eliminated.

Thanks to the shape of the filter fixing surface according to the invention, the deformation of the filter connecting piece in the area of the fixing surface is facilitated, since the radial convexities and/or concavities recreate the shape of a ring spring, the circumference of which can be elastically stretched or compressed. Thanks to this reduced deformation due to the variable radius, it is possible to improve the mechanical clamping and thus the fixation, for example, compared to a round or polygonal shape.

Preferably, the fixing surface of the filter is also a sealing surface of the filter. In this case, the spring action of the ring spring improves the seal, since the pressure of the spring ensures plane pressing of the sealing surfaces of the filter and reservoir. Due to the fact that in the described shape of the filter fixing surface there are no corners or edges, in addition to the spring action, this shape also provides improved sealing.

The elastic deformability of the filter fixing surface can be improved by the fact that the filter connecting member ring connecting piece provided with the filter fixing surface in the area of the filter fixing surface has an annular wall with an inner side and an outer side that are parallel or inclined relative to each other. Depending on whether the connection fitting is pushed over or inserted into the tank's retaining surface, either the outer side of the wall or the inner side of the annular wall forms the retaining surface of the filter.

Since in this configuration 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 as a whole as an annular spring. Thus, the annular wall is a ring spring with peripheral sides parallel or inclined relative to each other.

In addition, the ring-shaped filter connecting piece has 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 working position of the filter cartridge. Thereby, a guide is formed that facilitates insertion of the connecting piece into the gap between two mating surfaces on the tank side, wherein the surfaces on the tank side can form, at least in part, an inner and/or outer sealing surface of the tank.

Accordingly, the beveled outer wall may have an outer filter locking surface, and/or the beveled inner wall may have an inner filter locking surface and engage with the corresponding sealing surface of the reservoir into a locking and, in known cases, sealed connection with a positive lock.

In one of the improved embodiments of the invention, the configuration of convex and concavity of the filter fixing surface is characterized by rotational symmetry around the circumference. This ensures uniform distribution of the return force of the annular spring around the circumference and reliable fixation and sealing of the filter cartridge in the working position. A rotationally symmetrical configuration of the filter's fixing surface around the circumference is formed when the convexities and/or concavities are made to periodically oscillate along the circumference. This allows different angular positions of the filter cartridge, making it easier to attach. In addition, other technical functions depending on the angular position can be provided.

Reliable fixation of the filter cartridge in the working position is achieved due to the fact that the configuration of convex and concavity of the fixing surface of the filter is characterized by identical angles along the entire circumference. Consequently, a ring spring made in this way can be uniformly deformed around the circumference both in the region of convexities and in the region of concavities.

The convexities and concavities of the filter fixing surface may form a wave-like curve along a circular line, the wave-like shape consisting of alternating convex circular segments forming the convexes and concave circular segments forming the concavities. By sequentially changing along the circle line, a radial elastic action is achieved.

The elastic effect of the annular spring can be further enhanced if the concave and convex circular segments at the inflection points during the transition between concave and convex curvature are tangentially conjugate.

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 circumscribed angle of convex circular segments is also greater than the circumscribed angle of concave circular segments. Consequently, the tangential transition between different curvatures forms an acute angle with the central circumference of the ring spring, so that when deforming at the transition points there is no radial, inward or outward force.

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

The circular segments may be arranged such that the convex and concave circular segments lie inside the outer circumference circle and outside the inner circumference circle, with the center of the circle of the convex circular segments lying inside the inner circumference circle and the center of the circle of concave circular segments lying outside the outer circumference circle. This shape ensures that the circular segments located between the enveloping circles move gently relative to the enveloping circle or the center line, thereby facilitating the expansion or compression of the annular spring.

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

In addition, it turned out to be advisable to have the radius of the convex and/or concave circular segments be from 20% to 35% of the radius of the outer envelope of the circle.

The elastic effect of such a spring ring is more pronounced when the thickness of the wall between the outer side and the inner side parallel or inclined relative to it is from 7% to 10% of the radius of the outer circumference of the circle.

In addition, such a curve path turned out to be favorable in which the inflection points between the concave and convex circular segments lie closer to the inner envelope of the circle than to the outer envelope of the circle.

The filter fixing surface may define an outer surface of the annular connection fitting of the filter connecting element facing away from the central axis of the filter outlet. Despite the variable curvature along the circumference, such a filter connection fitting, installed in an opening on the side of the water reservoir with a corresponding radially inwardly facing locking surface of the reservoir, provides an outward elastic clamping pressure substantially along the entire circumference for proper locking. Conversely, when placed over a tank-side connection fitting with a corresponding radially outwardly facing tank locking surface, the radially inward-facing filter locking surface provides inward elastic clamping pressure over substantially the entire circumference for proper locking.

In one particular embodiment of the invention, both the inner side and the outer side of the filter connection piece are provided with filter fixing surfaces, one or both of which form a filter sealing surface. Such a filter connection piece can be placed in an annular slot located on the side of the reservoir, the side walls of which respectively form a fixing surface and/or a sealing surface of the reservoir.

From the point of view of the application of the elastomer seal, it is advantageous that the ring-shaped connecting piece of the filter connecting element, equipped with a filter fixing surface, is made, at least in the area of the filter fixing surface, which is also the sealing surface of the filter, of a polymeric material with a more constant shape than the elastomer during operation. temperature.

Thanks to this rigidity, the connection fitting of the filter cartridge, on the one hand, can still exert pressing pressure on the fixing surface of the tank with the fixing surface of the filter, ensuring a strong clamping fit. Such fixation can take place, for example, on the inner and/or outer side of the filter connection piece.

On the other hand, such a filter connecting piece of the filter cartridge can directly deform the elastomer seal on the water tank side so that it seals against the filter fixing surface, which is also the sealing surface of the filter. Such deformation may also occur on the inside and/or outside of the filter connection.

Depending on the embodiment, such a deformable elastomeric seal is located either internally or externally and is configured to form an annular gap into which a filter connection piece can be inserted.

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

The sealing effect of the filter sealing surface relative to the reservoir sealing surface can be improved, as described above, by having rounded convex and/or concavity shapes, eliminating the presence of corners or ridges.

Proper operation is ensured by a configuration including, for example, six convex and six concavity alternating along the line of a circle whose diameter is less than 3 cm.

The inlet of the filter cartridge may be configured on the outside of the filter connecting piece as a ring-shaped mesh hole through which water in the water tank can flow into the filter cartridge.

The improvement of the filter cartridge is achieved by providing a guide structure inside the filter connecting piece for guiding and placing the centering member located on the water tank side. Due to this, the filter cartridge, when installed in the corresponding water tank, is oriented in the axial direction and is fixed in this orientation in the operating position.

The guide structure includes at least one axially extending and parallel to the central axis guide groove for accommodating at least one centering element guide rib on the water tank side, such that the guide structure cooperates with a corresponding centering element on the side water tank provides axial movement of the filter cartridge when installed in the water tank, at least in one angular position and additional fixation in this position.

For guidance and fixation in several angular positions, the guide structure can be provided with several guide grooves distributed around the circumference.

Proper guidance of the filter cartridge to a given angular position occurs when the wall of the guide grooves is rounded in such a way that the width of the groove narrows from bottom to top relative to the operating position. The direction of the filter cartridge can be improved by having the wall of the guide grooves rounded so that the width of the groove tapers radially from the inside to the outside. In combination, these tapering groove shapes form a kind of funnel for the centering member fin to fit into the groove on the water reservoir side.

These groove shapes can be formed, for example, as internal bends of the wall of the guide structure connecting the guide grooves.

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

BRIEF DESCRIPTION OF THE DRAWINGS

In particular, the figures show:

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

Fig. 2 is a perspective view with spatial separation of the parts of the bottom of the tank with a centering element and a clamping ring,

Fig. 3 is a perspective view of the bottom of the tank according to FIG. 2 with inserted centering element and inserted clamping ring,

Fig. 4 is a top view of the bottom of the tank according to FIG. 2 and 3,

Fig. 5 is a side perspective view of the connecting area of the filter cartridge,

Fig. 6 is a perspective view of the connecting area of the filter cartridge obliquely from below,

Fig. 7 is a perspective view of the connecting fitting of the filter cartridge, cut off at a height, inserted into the bottom of the tank,

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

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

Fig. 10 is a perspective view of the centering element,

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

Fig. 11a and b are enlarged views of two parts of FIG. 11 to explain the closing bypass channel in the tank seal,

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

Fig. 12a is an enlarged view of part of FIG. 12 to explain the closed bypass channel,

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

Fig. 13a is an enlarged view of part of FIG. 13 and

Fig. 14 is a fragment showing the connecting area of the filter cartridge for explaining the guide means formed by beveling the guide rib.

DETAILED DESCRIPTION OF THE INVENTION

In fig. 1 shows a conventional design of a water tank 1 of a beverage preparation machine such as a coffee maker, for example a coffee vending machine of the prior art. The water tank 1 includes a tank bottom 2 and a water tank wall 3 partially shown in dashed lines. A filter cartridge 4 is installed in the water tank 1, including a filter housing 5. The connection between the tank bottom 2 and the filter cartridge 4 is provided by a tank connecting element 6 on the water tank side and a filter connecting element 7 on the filter side.

The filter cartridge 4 is located in the internal space 8 of the water tank 1, that is, when the device is operating, it is completely or partially in water, the supply of which is available in the water tank 1. From below, the connecting fitting 9 of the water tank 1 filter protrudes from the water tank 1 to connect the water tank 1 to the beverage preparation machine, which is not shown in the drawing.

In fig. 2 shows a round cutout of the bottom 2 of the tank, with a clamping ring 10 and a centering element 11 inserted into the recess 12 of the bottom 2 of the tank. In fig. 2 also shows a reservoir valve body 13 with an O-ring seal 14 from which two rods 15 project upward. The clamp ring 10 is provided with an elastomeric seal 16.

In fig. 3 and 4, the clamping ring 10 and the centering element are shown inserted into the bottom 2 of the tank. It can be seen that the rods 15 can pass through the centering element and thus constitute a codification element for matching the water tank and the machine connecting element, which, when installing the water tank, can actuate the tank valve body 13. In addition, in FIG. 4 it is clearly seen that the elastomeric seal 16, forming the reservoir seal 17, is an annular seal of variable radius R relative to the central axis A, so that the inner surface of the reservoir seal 17, which forms the first sealing surface 18 of the reservoir, has radial concavities 19 and radial convexities 20. the surface 18 of the reservoir is also the fixing surface of the reservoir.

In fig. 5 shows the connecting area 21 of the filter cartridge 22. The filter connecting fitting 23 forms a ring surrounded by an outer ring 24 with axially running projections 25 and depressions 26. Between the inner ring 23 and the outer ring 24 there is an annular mesh inlet 27, through which the filter cartridge receives water. The outer surface 28 and the inner surface 68 of the filter connecting piece 23 are equipped with convex 29 and concave 30 corresponding to the sealing surface 18 of the tank. The outer surface 28 and/or the inner surface 68 of the filter connecting piece 23 can simultaneously serve as a filter fixing surface.

In the view shown in FIG. 6, in addition to the above-described parts of the connecting area 21 of the filter cartridge 22, a configuration of a guide structure 31 of the filter cartridge 22 is shown for receiving the centering member 11. The guide structure includes guide grooves 32 coaxially arranged with the faces 33 of the polyhedral ring 34, in this case, for example, six guide grooves coaxial to the six faces of the hexagon-shaped ring. As shown in FIG. 7 in the cross-sectional image, when viewed from above, the cut plane passes through the polyhedral ring 34.

From bottom to top, internal bends 35 enter the inner space of the filter cartridge, lying between the edges 33 and the guide grooves 32. The internal bends 35 form the side walls 36 of the guide grooves 32. Thanks to the curved shape, the walls 36 of the guide grooves 32 narrow in the axial direction from bottom to top (relative to the working position) and in the radial direction from the inside to the outside. As shown in FIG. 8 in the sectional view, when viewed from above, the cut plane passes at a height where the guide grooves 32 are already clearly visible. In the center, a pressure line 37 adjoins the internal space, through which the water entering the filter cartridge 22 is directed upward to the filtration section.

In fig. 9 shows the filter cartridge 22 as a whole, which is provided with a filter housing 37 having an optional side metering hole 38 and the described water connection on the bottom side. The optional dosing hole 38 is only provided in the case of a filter cartridge, also intended to introduce additives such as minerals, vitamins, etc. into the water. from the dosing chamber filter located in housing 37. Since such a metering chamber within the filter housing 37 is closed with respect to the filtration section, this aspect is not significant from a filtration point of view. The filter cartridge according to the invention can also be simply designed without a dosing chamber and a corresponding dosing opening 38. In FIG. 9, first of all, you can see the operating position, to which the information given above and below in the present description relates.

In fig. 10 is a perspective view of the centering element 11. The centering element is provided with a support plate 39, which, when mounted, lies in the receiving seat of the elastomeric seal and rests against it on its sides. Projecting upward from the support plate 39 is a centering core 40 having an annular outer surface 41 which forms a second locking surface of the reservoir. The outer surface 41 has a variable radius along its circumference relative to the central axis A, thus the outer surface 41 has radial concavities 42 and convexes 43. Therefore, the outer surface 41 is consistent with the corresponding shape of the filter connecting piece 9.

To better coordinate the concavity 42 and convexity 43 of the outer surface 41, circles are made periodically oscillating along the line of the circle and have a rounded shape. In the illustrated embodiment, according to the illustrated embodiment, the filter cartridge 22 is provided with six concavities 42 and six convexes 43 on the line of the circle with a diameter of less than 3 cm. To match with the other filter cartridge, the outer surface 41 or the second fixing surface of the reservoir should be modified accordingly.

As a result of such matching of the shape of the outer surface 41 of the centering core 11 in the mounted state, only the annular gap between the outer surface 41 and the elastomeric seal 16 remains open for the introduction of the connecting fitting 23 of the filter. This provides an additional codification that prevents the use of an incorrect filter cartridge. In addition, it is thus possible to support the filter connecting piece 23 with its inner side on the outer surface 41 of the centering core. Therefore, the pressing pressure of the filter connecting piece on the elastomer seal 16 along the variable shape can be uniformly increased over the entire circumference.

Above the annular outer surface there is at least one protruding upward tooth 44. One or more teeth 44 are made on the stage 45 of the centering core 40. In addition, in accordance with the shape of the outer surface 41 at some distance from the teeth 44, the elevation 46 relative to the stage 45 designed in such a way that there is a free space 47 between the teeth and elevations 46. The tooth or teeth 44 and/or elevations 46 may prevent the application of the seal in violation of the codification. There is also a through hole 48 above the outer surface 41, which, when the centering element 11 is mounted, leads into the through hole of the reservoir. Through the through hole 48, the water filtered in the filter cartridge 22 can be drained from the water reservoir.

The support plate 39 has one or more through-bottom holes 49 under the outer surface 41. Unfiltered water can be drained from the water reservoir through the bottom holes. Under the elevations 46 inside the wall with the outer surface 41 there is a free space 50 for housing the reservoir valve housing 13.

Above the annular outer surface 41 there are guide ribs 51, which, as in the illustrated embodiment, can be beveled at the top. The guide bevels 52 thus formed facilitate the insertion of the guide ribs 51 into the guide grooves 32 of the filter cartridge 22. In the sectional view of FIG. 4, the guide bevels 52 of the guide ribs 51 in the mounted filter cartridge 22 are clearly visible.

In fig. 11, 11a, 11b, 12 and 12a, the parts of the water tank 1 intended for attaching a filter cartridge are shown assembled without a filter cartridge 22 or with a filter cartridge 22. The clamping ring 10 is equipped with a locking protrusion 53, which ensures its fastening to the bottom 2 of the tank and with which it rests against the edge 54 of the bottom of the water reservoir. The elastomeric seal 16 has a bottom portion 55 that engages with a clamp ring 10, causing the elastomeric seal 16 to be held by the clamp ring 10 at the bottom 2 of the tank.

The elastomeric seal 16 has a sealing surface designed to seal against the bottom 2 of the tank, which in this case is implemented as a sealing boss 56. To seal the seal between the elastomeric seal 16 and the clamp ring 10, the enveloping sealing surface can be provided at different locations. In the exemplary embodiment shown, there is an O-ring 57 above the elastomeric seal 16 that is sealed in the seal groove 58 of the clamp ring.

The elastomeric seal 16 includes an outer ring 59 and an inner ring 60 connected and formed as a single unit. The shape of the outer ring 59 and the inner ring 60 follows the shape of the variable-radius circle of the clamping ring 10, the filter connecting fitting 23 and the elastomeric seal 16 and the concavities and convexities formed by them. The outer ring 59 is stepped and includes an o-ring 57 and a sealing boss 56. The outer ring 59 is also provided with one or more bypass holes 61 through which unfiltered water in the flow direction P1 can enter the annular gap 62 between the outer ring 59 and the inner ring 60. The bypass hole 61 of the elastomer seal 16 in the assembled state is located immediately after the bypass hole 63 of the clamping ring 11, which can be seen, for example, also in FIG. 1 and 3. Through the bypass hole 63, unfiltered water can flow in the direction P2 through the annular gap 62 from the water tank 1 to the corresponding beverage machine.

On the underside of the inner ring 60 there is a seal lip 64 lying against the sealing surface 65 of the outer ring 59. In the relaxed state of the elastomeric seal 16, the annular gap 62 between the outer ring 59 and the inner ring 60 is open at the bottom, as shown in FIG. 11, and the unfiltered water directed to 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 water reservoir seal 17 is slanted downward. This bypass form is clearly shown in the enlarged views of Figs. 11a and b.

When installing the filter cartridge with the filter connection piece 23, the elastomeric seal 16 is deformed, the inner side 66 is deflected outward and runs essentially vertically along the filter connection piece. In this case, the working edge 64 of the seal is pressed against the opposing sealing surface 65 and, thus, closes the annular gap 62 and, consequently, the bypass flow through the bypass holes 61, 63. When deformed, a clamping pressure occurs, ensuring that the sealing surface 17 of the tank is pressed against the sealing surface 28 filter and, at the same time, the sealing lip 64 to the sealing surface 65. This condition is shown in FIG. 12 and fig. 12a.

In fig. 11 and fig. 12, the reservoir valve body 13 is raised, not shown in detail, by the stop of the corresponding machine towards the return spring 67 into the free space 50 and is in the open state that occurs when the water reservoir is installed on this machine. When the water reservoir is removed, the valve body 13 closes downward under the action of the return spring 67.

The sealing surface 18 of the reservoir is formed by the inner side 66 of the elastomeric seal and is also the first locking surface 18 of the reservoir. As already described above, on this side, under the action of pressing pressure, when the filter cartridge 5, 22 is in place, a first filter fixing surface 28 formed by the filter sealing surface 28 is adjacent, which deforms the elastomeric seal 16 in such a way that a positive connection occurs, providing fixation and sealing.

In this case, the outer surface 41 forming the second fixing surface of the filter is adjacent to the second fixing surface 68 of the filter (see Fig. 5), formed by the inner surface of the connecting fitting 23 of the filter. This form-fitting connection is also established under the action of clamping pressure. According to the form of the filter connection piece 23 according to the invention, it has an annular wall 69, which can be elastically stretched if necessary. In this way, the permissible deviations can be balanced and, through appropriate deformation, a secure fixation can be ensured. Parallel or inclined relative to each other, the first fixing surface 28 and the second fixing surface 68 form an annular wavy wall 69 of the connecting fitting 23 lying between them, which is a ring spring 70. The second filter fixing surface 68 can also serve as a second filter sealing surface.

The filter connection fitting corresponding to the front view shown in FIG. 13, as well as an enlarged image of its part shown in FIG. 13a, has the indicated wave-like shape with convexities 29 and concavities 30. The annular wall 69 of the filter connecting piece 23 of thickness W on the outer side 71 has a first fixing surface 28 and on the inner side 72 has a second fixing surface 68. The outer side 71 and the inner side 72 of the wall in the presented view they are parallel, but in the axial direction they are inclined to each other, which is further explained below. The wave-like shape is clearly represented by the dotted center line 73.

The center line 73 extends in a wave-like manner between the outer circumference 74, whose variable wave radius is characterized by larger values, and the inner circumference 75, the variable wave radius of which is characterized by smaller values. The convexities 29 and concavities 30 of the centerline 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 a convex circular segment 76 lie inside the inner enveloping circle 75, and in the case of a concave circular segment 77 lie outside the outer enveloping circle 74. The convex circular segments 76 and the concave circular segments 77 merge into each other tangentially and uniformly distributed around the circumference, so that a shape characterized by rotational symmetry is formed. In the illustrated embodiment, there are six convex circular segments 76 and six concave circular segments 77 alternating at an angular pitch of 30°, that is, the convex circular segments 76, like the concave circular segments 77, are spaced apart from each other by an angle α of 60°.

By selecting the radius of the segments and the resulting position of the corresponding midpoints 78, 79, a relatively flat centerline is obtained, undulating along the central circle 80. The center line 73 intersects the central circle 80 at an obtuse angle β. Due to this, the arc length of the convexes 29 is significantly greater than the arc length of the concavities 30, and the angle γ described by the arc of the convex segment 29 is significantly greater than the described angle δ of the concavities 30. Thanks to this shape, the elastic effect of the filter connecting piece 23 is improved.

For comparison, a drawing of a circular segment 81 is also shown, the midpoint 82 of which lies directly on the center line 73. This curve path, not implemented in this embodiment, is characterized by significantly smaller segment radii and a substantially perpendicular course of the center line 73.

Sufficient elastic force was achieved at a wall thickness such that the radius of the inner circumference 75 is between 5% and 15% of the radius of the outer circumference 74, and the radius of the convex and/or concave circular segments is between 20% and 35% of the radius of the outer circumference. 74. The thickness W of the wall between the outer side 71 and the parallel (relative to the operating position) or inclined relative to the inner wall side 72 is preferably from 5% to 15% of the radius of the outer circumference of the circle 74.

The example presented is characterized by a radius of the outer enveloping circle 74 of about 11 mm and a 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 thickness of the wall between the outer side 71 and the parallel or inclined relative to the inner wall side 72 is about 0.9 mm.

As shown in FIG. 14, the outer 71 and/or inner 72 wall of the filter connecting piece 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 and converge from top to bottom relative to the working position of the filter cartridge 4, 22. Such bevel or bevels at an angle ω1 and/or ω2 form a guide means for introducing the connecting fitting 23 into the annular gap between the elastomeric seal 16 and the outer surface 41 of the water tank 1.

List of positions in the drawings:

1 Water tank

2 Bottom of the water tank

3 Side wall of water tank

4 Filter cartridge

5 Filter housing

6 Tank connection

7 Filter connection element

8 Interior space

9 Filter connection fitting

10 Clamping ring

11 Centering element

12 Recess

13 Tank valve body

14 Seal

15 Rod

16 Elastomeric seal

17 Water tank seal/O-ring

18 Tank sealing surface

19 Concavity

20 Bulge

21 Connecting area

22 Filter cartridge

23 Filter connection fitting/inner ring

24 Outer ring

25 Ledge

26 Depression

27 Mesh inlet

28 Filter sealing surface/outer surface

29 Bulge

30 Concavity

31 Guide structure

32 Guide groove

33 Edge

34 Polyhedral ring

35 Internal bend

36 Wall

37 Filter housing

38 Dosing hole

39 Support plate

40 Centering core

41 Outer surface

42 Concavity

43 Bulge

44 Prong

45 Stage

46 Rise

47 Free space

48 Through hole

49 Through hole in the bottom

50 Free space

51 Guide rib

52 Guide bevel

53 Locking lug

54 Bottom rib

55 Bottom section

56 Sealing thickening

57 O-ring

58 Sealing groove

59 Inner ring

60 Outer ring

61 Bypass hole

62 Annular gap

63 Bypass hole

64 Seal lip

65 Sealing surface

66 Inner side

67 Return spring

68 Second fixing surface/inner surface

69 Wall

70 Ring spring

71 Outer side of the wall

72 Inner side of the wall

73 Centerline

74 Outer circumference circle

75 Inner circumference circle

76 Convex circular segment

77 Concave circular segment

78 Midpoint

79 Midpoint

80 Central circle

81 Circular segment

82 Segment midpoint

83 Inflection point

84 Tank through hole

A Axis

W Wall thickness

S Segment radius

P1 Flow direction

P2 Flow direction

Claims (21)

1. A filter cartridge (22) for a household device, having a filter housing (37), the wall of which separates the inner side of the housing from the outer side of the housing, while an inlet is provided that is open during operation of the filter cartridge (22) relative to the external environment around the filter housing (37). filter opening (27), wherein relative to the direction of flow during operation, after the filter inlet opening (27), a device is provided for supplying water inside the filter housing (37), in which there is at least one filter chamber equipped with at least one filter medium, and which ends with a filter outlet for draining water from the filter cartridge (22), and is provided with a filter connecting element with an annular connecting fitting (23) having an annular filter fixing surface (28) for sealing the filter cartridge (22) with the fixing surface water tank, characterized in that the shape of the filter fixing surface (28) along the circumference of the annular filter connecting piece (23) has a variable radius about the central axis, so that the filter fixing surface (28) has radial convexities (29) and/or radial concavities (30), while the convexities (29) and/or concavities (30) have a rounded shape, and the convexities (29) and concavities (30) form a wavy curve along the circle line (80), the wavy shape consisting of alternating convex circular segments (76) forming the convexes and concave circular segments (77) forming the concavities. 2. Filter cartridge according to claim 1, characterized in that the fixing surface (28) of the filter is also the sealing surface of the filter. 3. The filter cartridge according to one of the previous paragraphs, characterized in that, equipped with a filter fixing surface (28), the annular connecting fitting (23) of the filter connecting element at least in the area of the filter fixing surface (28) has a wall (69) with an outer side ( 71) wall including or forming a filter fixing surface (28) extending parallel to the inner side (72) of the wall. 4. The filter cartridge according to one of the previous paragraphs, characterized in that the arrangement of radial convexities (29) and radial concavities (30) of the filter fixing surface (28) around the circumference is rotationally symmetrical. 5. The filter cartridge according to one of the previous paragraphs, characterized in that the arrangement of convexes (29) and concavities (30) of the filter fixing surface (28) around the circumference is made with the same angles. 6. The filter cartridge according to one of the preceding claims, characterized in that the convexities (29) and concavities (30) of the sealing surface of the filter form a wavy curve along a line (80) of a circle, wherein the wavy shape consists of alternating convex circular segments (76), forming convexities, and concave circular segments (77) forming concavities. 7. Filter cartridge according to one of the previous paragraphs, characterized in that the concave and convex circular segments (76, 77) at the inflection points during the transition between concave and convex curvature are tangentially conjugate. 8. The filter cartridge according to one of the preceding claims, characterized in that the arc length of the convex circular segments (76) is greater than the arc length of the concave circular segments (77). 9. Filter cartridge according to one of the previous paragraphs, characterized in that the convex and concave circular segments (76, 77) have the same segment radius S. 10. The filter cartridge according to one of the previous paragraphs, characterized in that the convex and concave circular segments (76, 77) lie inside the outer enveloping circle (74) and outside the inner enveloping circle (75), while the center of the circle (78) of the convex circular segments (76) lies inside the inner enveloping circle (75), and the center of the circle of concave circular segments (77) lies outside the outer enveloping surface (74). 11. Filter cartridge according to one of the previous paragraphs, characterized in that the radius of the inner envelope circle (75) is from 5% to 15% of the radius of the outer envelope circle (74). 12. Filter cartridge according to one of the previous paragraphs, characterized in that the radius of the convex and/or concave circular segments (76, 77) is from 20% to 35% of the radius of the outer envelope of the circle (74). 13. The filter cartridge according to one of the previous paragraphs, characterized in that the thickness (W) of the wall between the inner side (72) and the outer side (71) extending parallel to it is from 5% to 15% of the radius of the outer envelope circle (74). 14. The filter cartridge according to one of the previous paragraphs, characterized in that the inflection points (83) between the concave and convex circular segments (76, 77) lie closer to the inner envelope circle (75) than to the outer envelope circle (74). 15. The filter cartridge according to one of the previous claims, characterized in that the ring-shaped connecting piece (23) of the filter connecting element is equipped with a filter fixing surface (28) at least in the area of the filter fixing surface (28), which at least is also the sealing surface of the filter , is made of a polymer material with a more constant shape than elastomer at operating temperature. 16. Filter cartridge (22) according to claim 1 or 2, characterized in that the ring-shaped connecting fitting (23) of the filter connecting element has an outer (71) and/or inner (72) wall, which in the operating position of the filter cartridge is inclined relative to the vertical at an angle ω1 and/or ω2 so that the outer wall (71) and the inner wall (72) converge from top to bottom. 17. Filter cartridge (22) according to one of the preceding claims, characterized in that the beveled outer wall (71) has an outer filter sealing surface (28) and/or the beveled inner wall (72) has an inner filter fixing surface.