Patent Abstract:
The invention describes an apparatus for the filtration of liquids and an associated filter cartridge  100 , the correct seating of which is ensured and can be established by the user. The apparatus is characterized in that the inlet funnel  10  has at least one first fixing means  30  below the receiving opening  13 , and in that the filter cartridge  100  has at least one second fixing means  130  below and at a distance from the sealing rim  160 , which second fixing means, when the filter cartridge  100  is being fitted into the receiving opening  13 , interacts with the first fixing means  30.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application claims priority under 35 U.S.C. §120 to and is a continuation application of previously filed U.S. patent application Ser. No. 11/597,189, filed Nov. 21, 2006, the entire disclosure of which is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to an apparatus for the filtration of liquids. The invention also relates to a filter cartridge for an apparatus of this type. 
     2. Description of the Related Art 
     Filter cartridges are to be understood as meaning on the one hand cartridges which have a screen-like formation for mechanical filtration. On the other hand, filter cartridges are also to be understood as meaning cartridges which, in addition to a screen-like formation, contain at least one filter medium, e.g. in granule form, which is used for the chemical and/or mechanical removal of organic and/or inorganic contaminants and/or to lower the levels of such contaminants. Filter cartridges equipped in this way therefore allow non-mechanical filtration, which may be combined with mechanical filtration. These filter cartridges are used to optimize water, the term optimization being understood as meaning mechanical and/or non-mechanical filtration. This includes, for example, softening and decalcification of drinking water. 
     A very wide range of embodiments of apparatuses for the filtration of liquids are known. 
     By way of example, there are filter apparatuses with spherical filter cartridges, which are screwed onto the inlet funnel from below by means of a bayonet catch, as described in WO 2004/014519 A2. 
     DE 199 05 601 A1 has disclosed an apparatus for the treatment of liquids, having an inlet funnel which has a receiving opening with a sealing rim. The filter cartridge is likewise fitted into the receiving opening from below and is pressed into the receiving opening by means of a separate securing ring. For this purpose, the filter cartridge is provided with a groove on the cartridge upper part below the sealing rim; the lower portion of the securing ring engages in this groove. The upper portion of the securing ring is guided in a groove of a connection piece formed integrally on the funnel base. The filter cartridge is complex to install and remove, requiring particular skill on the part of the operator. 
     Other embodiments provide for the inlet funnel to have, in its base wall, a receiving opening, into which the filter cartridge is fitted from above. The filter cartridge generally has a conical sealing rim, which bears against the edge of the receiving opening. The filter cartridge may become tilted during insertion, so that the intended sealing position is not adopted. 
     DE 199 158 29 A1 has disclosed a filter cartridge and an apparatus for treating liquids, in which the sealing rim has additional latching means, which interact with corresponding latching means in the region of the opening in the base of the inlet funnel. The latching means are brought into engagement with one another by a rotational movement. 
     In this embodiment, the filter cartridge is held only at the edge and is located in the filtrate space. If the apparatus is a kettle, therefore, the filter cartridge is also in the boiling space, which means that the filter cartridge could be damaged during the heating of the filtered liquid. Therefore, it is desirable for the filter cartridge to be arranged such that it is shielded from the filtrate space or boiling space. 
     Inlet funnels with a receiving chamber for the filter cartridge are used to remedy this problem. In this design too, the conical sealing rim of the filter cartridge bears against the rim of the receiving opening in the base wall of the inlet funnel. 
     The peripheral and base wall of the filter cartridge is arranged at a distance from the peripheral and base wall of the receiving chamber, so that during filtration, although filtered liquid can collect in this intermediate space, this liquid does not limit the quantitative flow through the apparatus. An outflow opening provided with a closure element is located in the base wall of the receiving chamber. 
     DE 198 46 583 A1 has disclosed a water filter device of this type, with a collection can and a heating element. The inlet funnel has a receiving chamber, into which the filter cartridge is fitted from above. The receiving chamber is formed by a filter insert, which may be fixedly connected to the inlet funnel or can be fitted into the receiving opening. The filter insert is matched to the conical shape of the filter cartridge and forms a guide element for the filter cartridge. Since the peripheral wall of the filter cartridge bears against the filter insert over its full surface, the two components can only be separated from one another with difficulty, in particular if the user pushes the filter cartridge too deep into the filter insert. On account of the fact that two conical surfaces are sliding along one another, it is not clear to the user when he has reached the limit position which is required for optimum seating of the filter cartridge and defines the sealing position of the filter cartridge. 
     U.S. Pat. No. 4,020,350 describes a filter system which is connected to a water pipe via two connections. The filter system comprises a housing upper part and a housing lower part, which are screwed together after the filter cartridge has been fitted. The cover and base wall of the filter cartridge have cup-shaped indentations, in which correspondingly shaped connection pieces of the housing parts for supplying the unfiltered liquid and removing the filtered liquid, engage. To change the filter cartridge, the two housing parts have to be unscrewed. 
     In all the known filter apparatuses, it is necessary for the filter cartridge to be matched to the desired quantitative flow. 
     BRIEF SUMMARY OF THE INVENTION 
     It is an object of the invention to provide a filter cartridge and an apparatus for the filtration of liquids with which correct seating of the filter cartridge is ensured and can be established by the user. 
     This object is achieved by an apparatus in which the inlet funnel has at least one first fixing means below the receiving opening, and the filter cartridge has at least one second fixing means below and at a distance from the sealing rim; when the filter cartridge is being fitted into the receiving opening, the at least one second fixing means interacts with the first fixing means. 
     The filter cartridge can preferably be fitted into the receiving opening in its axial direction. 
     The fixing means are arranged in such a manner that during interaction they define the sealing position of the filter cartridge, i.e. when the fixing means interact, the sealing rim of the filter cartridge in its intended position bears against the edge of the receiving opening. 
     The interaction of the fixing means is associated with a resistance, which is perceptible to the user when he is fitting the filter cartridge and indicates to the user that the intended position of the filter cartridge has been reached. 
     Since the fixing means define the sealing position of the filter cartridge, it is advantageous if the distance between sealing rim and fixing means is selected to be as great as possible. This prevents the filter cartridge from tilting or being incorrectly positioned. 
     Therefore, the second fixing means are preferably arranged on the lower half, preferably in the bottom third, of the filter cartridge, in particular in the region of the base wall of the filter cartridge. 
     The first and/or second fixing means may be spacer elements and/or guide elements and/or latching elements. This means that a fixing means can perform one or more functions, and that it is also possible for a plurality of fixing means of different configurations to be realized in an apparatus. 
     The fixing means are preferably projections or recesses. The projections or recesses may be cylindrical, conical or frustoconical in form. These forms also include, for example, indentations and protuberances or beads. 
     In the case of latching elements, latching bosses, latching recesses or annular beads are preferred. 
     In the simplest case, the fixing means may be spacer elements. By way of example, at least one outwardly facing projection may preferably be formed integrally on the base wall of the filter cartridge as second fixing means, which projection, during fitting of the filter cartridge, is seated on a holding element which is arranged on the inlet funnel and forms the first fixing means. 
     The first fixing means may, for example, also be the base wall of a receiving chamber arranged at the inlet funnel. 
     Conversely, by way of example, it is also possible for the holding element, which may form the base wall of the receiving chamber, to have at least one inwardly facing projection, which interacts with the base wall of the filter cartridge, which in this case forms the second fixing means. 
     The fixing means may also be guide elements, which means that the filter cartridge is guided into its intended position when it is being fitted. By way of example, projections and recesses, in particular indentations on the filter cartridge and on the holding element which, by way of example, may be cylindrical, conical or frustoconical in form, are suitable for this purpose. 
     According to a further embodiment, the fixing means may also be latching elements which engage in one another as they interact. The latching or snapping into place is generally associated with a noise which indicates to the user that the filter cartridge has reached its intended position. 
     The fixing means are preferably matched to one another in such a manner that fitting the filter cartridge in the axial direction is sufficient to bring the fixing means together. Therefore, there is no need either for rotary, tilting or other movements of the filter cartridge or for additional components, such as securing rings or the like, which overall makes insertion of the filter cartridge user-friendly. 
     Furthermore, the fixing means are matched to one another in such a manner that they can be detached from one another without particular effort when the filter cartridge is being exchanged. 
     This is achieved, inter alia, by the contacting surfaces of the fixing means being kept small in the case of guide elements, in order to prevent the filter cartridge from jamming or sticking in place. 
     If the fixing means are designed as latching elements, the latching or clamping forces are kept low, in such a manner that the filter cartridge can be removed by simply being pulled out of the receiving opening in the axial direction. The latching elements are therefore preferably designed in such a manner that an axial movement of the filter cartridge is sufficient to fit or remove it. 
     It is preferable for the first fixing means to be arranged on a holding element arranged at the underside of the funnel base wall. A holding element of this type may be designed in various ways. A holding element in the form of a holding bracket which spans the receiving opening below the latter is preferred. 
     According to a further embodiment, the holding element may be a receiving chamber which is arranged in the funnel base wall, has at least one outflow opening and has a base wall and a peripheral wall. 
     Preferably, the base wall of the receiving chamber has at least one first indentation, and the base wall of the filter cartridge has at least one second indentation, which engages over the first indentation. These two indentations may interact in a sliding manner and thereby form guide elements. Moreover, these indentations may also be provided with latching elements which engage in one another when the filter cartridge is being fitted. 
     Preferably, the first indentation is a cylindrical or frustoconical hollow body, which is formed integrally on the base wall of the receiving chamber, faces inwards and has at least one inwardly facing first bead, which is in the shape of an arc of a circle and leaves clear at least one outflow opening, arranged on its free edge, wherein an outwardly facing mandrel, which engages in the cylindrical or frustoconical hollow body when fitting the filter cartridge, is arranged in the second indentation. 
     In this embodiment, the first guide element is formed by the at least one bead, which is in the form of an arc of a circle and slides along the outer side of the mandrel when the filter cartridge is being inserted. The bead does not extend over the entire inner periphery of the hollow body, and consequently a free space remains which, after fitting of the mandrel, which represents the second guide element, forms the outflow opening. A plurality of arcuate beads or bead segments may be arranged at a distance from one another in the peripheral direction, so that a plurality of outflow openings are created. 
     According to a further embodiment, the mandrel has at least one second bead in the shape of an arc of a circle on its outer side, which second bead engages behind the first bead during fitting of the filter cartridge. In this case, the first and second beads form latching elements. 
     It is preferable for the hollow body and the mandrel each to be arranged centrally. This arrangement has the advantage that in each case only one fixing means is required, and as a result the space required for the fixing means can be kept small, and consequently more volume is available for the filter medium. 
     It is preferable for the receiving chamber to have the first indentation in the region of base and peripheral wall and for the filter cartridge to have the second indentation likewise in the base and peripheral wall. 
     The first and second indentations may preferably be cuboidal in form, so that the two indentations each have two side walls, one end wall and one covering wall. The two indentations may be in the form of guide elements which engage in one another or slide into one another. 
     It is advantageous if the first indentation has first latching means on two side walls and the second indentation has second latching means on two side walls. This embodiment has the advantage that it is possible to realize greater latching forces, for example in devices in which water is heated. The two indentations may have different dimensions, which brings the advantage that there is only one possible position for the filter cartridge. 
     The fixing means allow accurate positioning of the filter cartridge, so that not only is the optimum position of the sealing rim at the receiving opening ensured, but also a defined distance can be set between the filter cartridge and the wall of the receiving chamber. The cross section of the flow passage between outlet opening of the filter cartridge and outflow opening of the receiving chamber can thus likewise be set in a targeted way. 
     This also enables a throttling device to be arranged between the outlet opening in the filter cartridge and the outflow opening in the receiving chamber. 
     The quantitative flow through the filter cartridge substantially depends on the type of filter medium and the size of the outlet opening(s) in the filter cartridge. Depending on the particular application, for example in filter systems of which a high performance is demanded of the filter medium, it may be necessary to reduce the quantitative flow which is predetermined by the filter cartridge. To achieve this, hitherto the cartridge has been modified, i.e. suitable filter cartridges had to be produced and kept in stock for every desired quantitative flow. The advantage of the throttling device is firstly that only one type of filter cartridge is required, and the quantitative flow can be set by selecting a suitable receiving chamber or a suitable inlet funnel. 
     Secondly, it is advantageous with this configuration that if the cartridge is not present the appliance can be operated without any flow restrictions. 
     It is preferable for the throttling device to be designed in such a manner that the quantitative flow delivered by the filter cartridge can be reduced by more than 0 up to 95%, in particular by 10 to 80%, particularly preferably by 20 to 70%. 
     It is preferable for the filter cartridge to be arranged in the region between outlet opening and outflow opening, at a distance from the peripheral wall and/or base wall of the receiving chamber, thereby forming a flow passage. The minimum cross section of the flow passage then forms the throttling device. 
     The cross section of the flow passage can be accurately set by the fixing means. 
     A preferred embodiment provides for at least one fixing means to form the throttling device. By way of example, if a spacer element formed integrally on the filter cartridge or the receiving chamber is arranged in the flow passage, the cross section is reduced at this location. The action of the throttling device can easily be set by means of the dimensions of one or more spacer elements of this type. 
     It is preferable for the indentations of filter cartridge and receiving chamber to be arranged at a distance from one another at least in subregions, so that a reduced cross section of flow, which forms the throttling device, is set between the indentations. 
     Alternatively, the outflow opening or outflow openings may form the throttling device, in which case the cross section of the outflow opening/openings is smaller than the cross section of the outlet opening/outlet openings in the filter cartridge. 
     A preferred embodiment provides for the cross section of the outflow opening/outflow openings defined by the bead or beads on the cylindrical or frustoconical hollow body to be selected in such a way that this/these outflow opening(s) has/have a throttling action. 
     For a predetermined filter cartridge, the throttling device may be adjustable by selecting a receiving chamber of suitable dimensions or with a suitable cross section of the outflow opening. 
     The desired quantitative flow can therefore be set by means of the inlet funnel, which is advantageous in that the inflow funnel, unlike the filter cartridge, does not represent a consumable item. The consumable item formed by the filter cartridge only has to be produced and kept in stock in one design, and the quantitative flow can be defined by the selection of inlet funnel. This makes it possible to significantly reduce the manufacturing costs of the apparatus and the costs of spares. 
     It is preferable for the outflow opening in the receiving chamber to be arranged above the outlet opening in the filter cartridge, so as to create a siphon-like arrangement. A siphon-like arrangement of this type has the advantage, in particular in conjunction with the throttling device, that the filter medium is kept moist even in the event of breaks in filtration, and therefore its full operational readiness is ensured even without renewed conditioning. 
     The presence of fixing means also allows a new type of configuration of the sealing rim of the filter cartridge, allowing the correct seating of the filter cartridge and the sealing position to be improved further. 
     For this purpose, provision is made for the sealing rim to be a snap-action rim which is connected to one of the two cartridge parts via an integral hinge, it being possible for the snap-action rim to be flipped from a first, lower snap-action position into an upper, second snap-action position and vice versa, and for the funnel base wall to have a sealing seat, which surrounds the receiving opening and into which the snap-action rim snaps in its second position. 
     With the snap-action rim in its lower snap-action position, the filter cartridge is fitted into the receiving opening from above and pressed downwards until the snap-action rim flips upwards and in the process snaps into the sealing seat. The sealing seat is matched to the snap-action rim in such a manner that when the snap-action rim has snapped into place, the filter cartridge bears in a sealing manner against the edge of the receiving opening and is fixed in place. 
     The snap-action indicates to the user that the filter cartridge has adopted its predetermined sealing position. This prevents both incorrect positioning by the user and slipping of the filter cartridge during transport. 
     To remove the filter cartridge, it is simply pulled out upwards, during which operation the snap-action rim flips into its lower snap-action position. 
     The snap-action rim is preferably formed by a flat edge strip which extends outwards in the radial direction. 
     In this embodiment, fixing means in the form of guide elements are sufficient. Here, fixing means in the form of latching elements could be disadvantageous since in the event of what is known as double latching at the sealing rim and, for example, in the region of the base, the tolerances which have to be observed make production costs correspondingly high. 
     In the case of a filter cartridge in which the cartridge upper part has an outwardly facing first securing flange and the cartridge lower part has an outwardly facing second securing flange, via which the two cartridge parts are connected to one another, the snap-action rim is preferably connected to one of the two securing flanges by way of the integral hinge. 
     The sealing seat at the inlet funnel is matched to this snap-action rim. It is preferable for the sealing seat to merge into a conically protruding rim section with an inwardly open abutment section, on which the outer edge of the snap-action rim engages. 
     The abutment section may be a groove or a step with at least one inclined surface. 
     The filter cartridge, which can be fitted into the inlet funnel and has a cartridge upper part with at least one inlet opening, a cartridge lower part with at least one outlet opening and a sealing rim, is characterized by least one fixing means arranged below and at a distance from the sealing rim. 
     The fixing means at the filter cartridge is preferably a spacer element and/or guide element and/or latching element. The fixing means may be recesses and projections, the projections or recesses preferably being cylindrical, conical or frustoconical in form. The latching element may be a latching boss, a latching recess or an annular bead. 
     The fixing means is preferably arranged in the region of the lower half of the filter cartridge, preferably in the region of the bottom third and in particular in the region of the base wall of the filter cartridge. 
     The cartridge lower part has at least one indentation, with an outwardly facing mandrel preferably being arranged in the indentation. 
     According to a further embodiment, the indentation may also be cuboidal in form. 
     The sealing rim is preferably a snap-action rim which is connected to one of the two cartridge parts via an integral hinge, it being possible for the snap-action rim to be flipped from a first, lower snap-action position into an upper, second snap-action position and vice versa. 
     If the filter cartridge has a sealing flange on its upper and lower parts, the snap-action rim is preferably connected to one of the two securing flanges by way of the integral hinge. 
     The snap-action rim is preferably formed by a flat edge strip which is directed radially outwards. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       Exemplary embodiments of the invention are explained in more detail below with reference to the drawings, in which: 
         FIGS. 1   a, b  show vertical sections through an inlet funnel with fitted filter cartridge in accordance with two embodiments, 
         FIG. 2  shows a perspective view, partially in section, of an inlet funnel in accordance with a further embodiment, 
         FIG. 3  shows a vertical section through an inlet funnel with fitted filter cartridge in accordance with a further embodiment, before the filter cartridge has reached its limit position, 
         FIG. 4  shows a section on line F-F through the apparatus shown in  FIG. 3 , 
         FIG. 5  shows an enlarged sectional illustration of the region of the two indentations in accordance with  FIG. 3 , 
         FIG. 6  shows an enlarged sectional illustration of the region of the two indentations after the filter cartridge has been fitted and positioned, 
         FIG. 7   a  shows a plan view of the frustoconical hollow body in accordance with  FIG. 3 , 
         FIG. 7   b  shows a plan view of a frustoconical hollow body in accordance with the a further embodiment, 
         FIG. 8  shows a vertical section through the frustoconical hollow body on line H-H in  FIG. 7   b,    
         FIG. 9  shows an enlarged sectional illustration of the lower region of the two indentations in accordance with a further embodiment, on line G-G through the frustoconical hollow body in  FIG. 7   a,    
         FIG. 10  shows a vertical section through a filter cartridge, 
         FIG. 11  shows a plan view of the filter cartridge shown in  FIG. 10 , 
         FIG. 12  shows an enlarged sectional illustration of an edge region of the filter cartridge illustrated in  FIGS. 10 and 11 , 
         FIG. 13  shows an enlarged sectional illustration of a region of the receiving opening in the inlet funnel, 
         FIG. 14  shows an enlarged sectional illustration of the region of the receiving opening in the inlet funnel with initially positioned snap-action rim of a filter cartridge, 
         FIG. 15  shows an enlarged illustration of the region of the receiving opening of an inlet funnel with the snap-action rim of the filter cartridge snapped into position, 
         FIG. 16  shows a vertical section through the region of the receiving opening in the inlet funnel in accordance with a further embodiment, 
         FIG. 17  shows a vertical section through an inlet funnel with a fitted filter cartridge in accordance with a further embodiment, 
         FIG. 18  shows a section on line B-B through the apparatus shown in  FIG. 17 , 
         FIG. 19  shows an enlarged sectional illustration of the region of the outflow opening of the apparatus shown in  FIG. 17 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1   a  illustrates a vertical section through an inlet funnel  10  with fitted filter cartridge  100 . The inlet funnel  10  has a peripheral wall  11 , which merges into a funnel base wall  12  which has a receiving opening  13 . A receiving chamber  14 , which once again has a peripheral wall  15  and a base wall  16 , extends downwards from the receiving opening  13  as holding element  20 . 
     The filter cartridge  100  is fitted into this receiving chamber  14  axially from above; the filter cartridge  100  comprises a cartridge upper part  101  and a cartridge lower part  110 . The cartridge upper part  101  is configured in the shape of a roof and has inlet openings  102 . A sealing rim  160 , which bears against the sealing seat  60  of the inlet funnel  10  in the region of the receiving opening  13 , is provided in the connection region of cartridge upper part  101  and cartridge lower part  110 . 
     The cartridge lower part  110  of the filter cartridge  100  has a peripheral wall  111  and a base wall  112 , in which outflow openings  113  are arranged. 
     The receiving chamber  14  is configured in such a manner that the peripheral wall  111  of the filter cartridge  100  is arranged at a distance from the peripheral wall  15  and from the base wall  16 . Consequently, the filtered liquid collects in the lower region of the receiving chamber  14  and flows away via the outflow openings  17  shown to the right and left in the figure. 
     The receiving chamber  14  with the peripheral wall  15  and the base wall  16  forms a holding element  20  for the filter cartridge  100 . A second fixing means  130 , which in the embodiment shown here forms a spacer element, is formed integrally in the centre of the base wall  112  of the filter cartridge  100 . This second fixing element  130  bears against the inner side of the base wall  16 , which therefore performs the function of a first fixing element  30 . 
     The filter cartridge  100  is fitted into and removed from the receiving chamber  14  of the inlet funnel  10  in the axial direction, as indicated by the double arrow. When the limit position provided during fitting is reached, the second fixing means  130  bears against the first fixing means  30 , i.e. the base wall  16  of the receiving chamber  14 . The operator notices this as a result of the resistance which then occurs, which indicates to the operator that the limit position has been reached. In this limit position, the sealing rim  160  bears in a sealing manner against the sealing seat  60  of the receiving opening  13 . As a result, the optimum position of the filter cartridge  100  has been reached. 
       FIG. 1   b  illustrates a further embodiment of the apparatus, which differs from the apparatus shown in  FIG. 1   a  by virtue of the fact that two first fixing means  30 , in the form of indentations  31  designed as spacer elements, are formed integrally on the inner side of the base wall  16 . The base wall  112  of the filter cartridge  100  bears against these two spacer elements  30 . 
     In this embodiment, the base wall  112  performs the function of the second fixing means  130 . 
     The two first fixing means  30  are arranged in the flow passage  201  between the outlet openings  113  and the outflow openings  17  and at this location reduce the cross section of flow. Depending on the particular configuration and dimensions, the fixing elements  30  in each case form a throttling device  200 . 
       FIG. 2  illustrates a further embodiment of an inlet funnel  10 , which does not have a receiving chamber  14 , but rather instead, as holding element  20 , has a holding bracket  21  which comprises the two substantially vertical limbs  22   a, b  and a cross-bar  23 . This holding bracket  21  spans the receiving opening  13  below the receiving opening  13 , so that a filter cartridge (not shown) can be fitted. The dimensions of the holding bracket  21  are matched to the dimensions of the filter cartridge  100  to be fitted. 
     In the central region, the cross-bar  23  has a first fixing element  30  in the form of a first indentation  31 . This indentation  31  is conical in form and extends vertically upwards. The associated filter cartridge  100  (not shown), in the region of its base wall, has a corresponding conical or frustoconical indentation (second indentation  130 ), so that the two fixing elements interact during fitting of the filter cartridge  100  in the axial direction, in such a way as to guide the filter cartridge. In this configuration, the fixing elements  30 ,  130  serve as spacer elements and guide elements. 
       FIG. 3  illustrates a vertical section through a further embodiment of the apparatus. The inlet funnel  10 , of which the upper part has been omitted for the sake of clarity, has a first indentation  31 , which is designed a frustoconical hollow body  32 , arranged in the centre of its base wall  16 . A bead  34  in the form of an arc of a circle is formed integrally on the inner side of the free edge  33  of the hollow body  32 , which bead  34 , as illustrated in  FIG. 7   a , does not form a continuous ring, but rather has a free space  18  which forms the outflow opening  17  after the filter cartridge has been fitted. 
     In its base wall  112 , the filter cartridge  100  likewise has an indentation  131  in which a mandrel  132 , which extends vertically downwards, is formed integrally. When the filter cartridge  100  is being fitted into the receiving chamber  14 , the mandrel  132  engages in the frustoconical hollow body  32 , with the outer surface  133  of the mandrel  132  sliding along the bead  34 . In this embodiment, the mandrel  132  and the bead  34  form first and second fixing means  30 ,  130  which serve as guide elements. The outflow opening  17  is formed between the outer surface  133  of the mandrel  132  and the wall  35  of the hollow body  32 . 
       FIG. 3  illustrates the filter cartridge  100  at the start of the fitting operation. The sealing rim  160 , which in the embodiment shown here is designed as a snap-action rim  161 , is therefore not yet in its limit position. The snap-action rim  161  will be described separately below. 
       FIG. 4  illustrates a section on line F-F through the apparatus shown in  FIG. 3 . It can be seen from this figure that the mandrel  132  bears against the bead  34  in the form of an arc of a circle and at this location also forms a seal apart from the outflow opening  17  (which is not visible in  FIG. 4 ). 
       FIG. 5  illustrates an enlarged view of the lower region of filter cartridge  100  and receiving chamber  14 , illustrating the fitting state in accordance with  FIG. 3 . The second indentation  131  has a base wall  134   a  and an annular wall  134   b , which extends upwards from the base wall  112 . Spacer ribs  139  are formed integrally on the underside of the base wall  134   a.    
     In  FIG. 6 , the filter cartridge  100  has reached its limit position and therefore its sealing position. A flow passage  201  is formed between the base wall  112  of the filter cartridge  100  and the base wall  16  of the receiving chamber  14  and merges, in the region of the two indentations  31 ,  131 , into a rising annular passage  202  which is formed between wall  35  of the hollow body  32  and the annular wall  134   b . The cross section of the annular passage  202  is smaller than that of the flow passage  201 , so that a throttling device  200 ′ is formed. 
     However, the annular passage  202  only forms the throttling device  200 ′ if the outflow opening  17  has a significantly larger cross section. In the embodiment shown here, there is only a single outflow opening  17 , which has a smaller cross section of flow than the cross section of the annular passage  202 , and consequently the outflow opening  17  can be equated to the throttling device  200 ′. The two fixing elements  30 ,  130  in the form of the annular bead  34  and in the form of the mandrel  132  therefore form the throttling device  200  in the assembled state. The spacer ribs  139  bear against the end face  39  of the hollow body  32  and therefore, as spacer elements, form second fixing means  130 . 
       FIG. 7   b  illustrates a further embodiment of the hollow body  32 , which differs from the embodiment illustrated in  FIG. 7   a  by virtue of the fact that a total of four beads  34  in the form of arcs of a circle are arranged spaced apart from one another, so that free spaces  18  for the outflow openings  17  in each case remain between the beads  34 . Whether the combination of these outflow openings form a throttling device  200  depends on the cross-sectional dimensions of the flow passage, in particular of the annular passage  202  in the region of the frustoconical hollow body  32 . 
       FIG. 8  illustrates the hollow body  32  in vertical section on line H-H in  FIG. 7   b . The triangular shape of the arcuate beads  34  has the advantage of minimizing the surface area of the contact surface with the mandrel that is to be introduced, so that the frictional forces are correspondingly low and the filter cartridge can be fitted and removed without difficulty. 
       FIG. 9  illustrates a further embodiment, in which the mandrel  132  is likewise provided with a bead (second bead)  135  on its outer surface. In this case, the section through the frustoconical hollow body  32  is taken on line G-G from  FIG. 7   a . When the filter cartridge  100  is being fitted, the mandrel  132  engages in the hollow body  32 , with the annular bead  135  engaging behind the bead  34  when the spacer ribs  139  are bearing against the end face  39 . Free spaces (not visible in this figure) are provided between the spacer ribs  139 , so that the liquid can flow to the outflow opening  17 . In this embodiment, the beads  34  and  135  form latching elements, and the spacer ribs  139  form spacer elements, with the end face  39  of the hollow body  32 , as first fixing means  30 , forming a stop. 
       FIG. 10  illustrates a vertical section through a filter cartridge  100  in order to explain the function of the sealing rim  160  in conjunction with the following figures. The cartridge upper part  101  has a securing flange  120 , which is joined to the securing flange  121  of the cartridge lower part  110 , preferably by welding. The securing flange  120  extends radially outwards and has an integral hinge  162 , via which the snap-action rim  161  is attached in jointed fashion. The snap-action rim  161  is formed by a flat edge strip directed radially outwards. 
       FIG. 10  illustrates the snap-action rim  161  in its lower position. As illustrated in  FIG. 11 , the snap-action rim  161  is designed to run continuously all the way around, as is the integral hinge  162 . A dead centre has to be overcome when the snap-action rim is being flipped from a lower snap-action position into an upper snap-action position. 
       FIG. 12  illustrates the snap-action rim  161  on an enlarged scale. The integral hinge  162  is formed as an encircling groove  163  on the underside of the securing flange  120 . 
       FIG. 13  illustrates the corresponding receiving opening  13  in section and on an enlarged scale. The sealing seat  60  with which the snap-action rim  161  interacts during fitting of the filter cartridge has a conically protruding edge section  61 , which merges into the abutment section  62 , which in the embodiment shown in  FIG. 13  is designed as a groove  63 . The groove  63  is open on the radially inner side, so that the snap-action rim  161  can engage therein, as can be seen in the following  FIGS. 14 and 15 . 
       FIG. 14  illustrates the start of the snap-action process. The snap-action rim  161  is still in its lower position and is engaging against the conically protruding edge section  61 . 
     As the filter cartridge  100  continues to be lowered, the snap-action rim  161  is moved into its upper position, with the outer edge  164  of the snap-action rim  161  engaging in the groove  63 , as illustrated in  FIG. 15 . There is no need for the whole of the surface of the snap-action rim  161  to bear against the surface  61 . Sealing is effected in the region of the groove  63 . 
       FIG. 16  illustrates an alternative to the groove  63 . The abutment section  62  comprises a step  64  which has a substantially horizontal surface  66  and an inwardly inclined surface  65 . 
       FIG. 17  illustrates a vertical section through an inlet funnel  10  with fitted cartridge  100  in accordance with a further embodiment. The filter cartridge  100  has a conventional sealing rim  160 , which bears against the sealing seat  60  in the region of the receiving opening  13 . Two cuboidal indentations  36  and  37  are formed integrally in the peripheral wall  15  and the base wall  16  of the receiving chamber  14 . These indentations  36 ,  37  each have two side walls  40 ,  41  (not visible), an end wall  42  and a covering wall  43 . The outflow opening  17  is located in the end wall  42 . 
     The cartridge  100  also has corresponding indentations  136  and  137 , which are likewise cuboidal in design, with side walls  140 ,  141  (not visible in  FIG. 17 ), end wall  142  and covering wall  143 , with the mutually corresponding walls of cartridge and receiving chamber being arranged at a distance from one another, so that flow passages  201  are formed between the walls. 
       FIG. 18  illustrates a section on line B-B. Fixing means  30 ,  130  in the form of latching elements are provided in the two side walls  40 ,  41 ,  140 ,  141  of the cuboidal indentations  36 ,  136 . The latching elements are latching bosses  38  which engage in corresponding latching recesses  138 . 
     This configuration of the latching elements is to be found on both cuboidal indentations  36 ,  37 ,  136 ,  137 . 
       FIG. 19  shows an enlarged illustration of the cuboidal indentations  37 ,  137 . 
     
       
         
               
             
               
               
               
             
           
               
                   
               
               
                 List of designations 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 10 
                 Inlet funnel 
               
               
                   
                 11 
                 Peripheral wall 
               
               
                   
                 12 
                 Funnel base wall 
               
               
                   
                 13 
                 Receiving opening 
               
               
                   
                 14 
                 Receiving chamber 
               
               
                   
                 15 
                 Peripheral wall 
               
               
                   
                 16 
                 Base wall 
               
               
                   
                 17 
                 Outflow opening 
               
               
                   
                 18 
                 Free space 
               
               
                   
                 20 
                 Holding element 
               
               
                   
                 21 
                 Holding bracket 
               
               
                   
                 22a, b 
                 Limb 
               
               
                   
                 23 
                 Cross-bar 
               
               
                   
                 30 
                 First fixing means 
               
               
                   
                 31 
                 First indentation 
               
               
                   
                 32 
                 Frustoconical hollow body 
               
               
                   
                 33 
                 Free edge 
               
               
                   
                 34 
                 Bead in the form of an arc of a circle 
               
               
                   
                 35 
                 Wall of the hollow body 
               
               
                   
                 36 
                 Cuboidal indentation 
               
               
                   
                 37 
                 Cuboidal indentation 
               
               
                   
                 38 
                 Latching boss 
               
               
                   
                 39 
                 End face 
               
               
                   
                 40 
                 Side wall 
               
               
                   
                 41 
                 Side wall 
               
               
                   
                 42 
                 End wall 
               
               
                   
                 43 
                 Covering wall 
               
               
                   
                 60 
                 Sealing seat 
               
               
                   
                 61 
                 Conically protruding edge section 
               
               
                   
                 62 
                 Abutment section 
               
               
                   
                 63 
                 Groove 
               
               
                   
                 64 
                 Step 
               
               
                   
                 65 
                 Inclined surface 
               
               
                   
                 66 
                 Horizontal surface 
               
               
                   
                 100 
                 Filter cartridge 
               
               
                   
                 101 
                 Cartridge upper part 
               
               
                   
                 102 
                 Inlet opening 
               
               
                   
                 110 
                 Cartridge lower part 
               
               
                   
                 111 
                 Peripheral wall 
               
               
                   
                 112 
                 Base wall 
               
               
                   
                 113 
                 Outlet opening 
               
               
                   
                 120 
                 Securing flange on upper part 
               
               
                   
                 121 
                 Securing flange on lower part 
               
               
                   
                 130 
                 Second fixing means 
               
               
                   
                 131 
                 Second indentation 
               
               
                   
                 132 
                 Mandrel 
               
               
                   
                 133 
                 Outer surface 
               
               
                   
                 134a 
                 Base wall 
               
               
                   
                 134b 
                 Annular wall 
               
               
                   
                 135 
                 Second bead 
               
               
                   
                 136 
                 Cuboidal indentation 
               
               
                   
                 137 
                 Cuboidal indentation 
               
               
                   
                 138 
                 Latching recess 
               
               
                   
                 139 
                 Spacer rib 
               
               
                   
                 140 
                 Side wall 
               
               
                   
                 141 
                 Side wall 
               
               
                   
                 142 
                 End wall 
               
               
                   
                 143 
                 Covering wall 
               
               
                   
                 160 
                 Sealing rim 
               
               
                   
                 161 
                 Snap-action rim 
               
               
                   
                 162 
                 Integral hinge 
               
               
                   
                 163 
                 Encircling groove 
               
               
                   
                 164 
                 Outer edge 
               
               
                   
                 200, 200′ 
                 Throttling device 
               
               
                   
                 201 
                 Flow passage 
               
               
                   
                 202 
                 Annular passage

Technology Classification (CPC): 2