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[0001]    This application is a continuation of PCT application number PCT/IL99/00616, filed Nov. 21, 1999 and published as WO 01/38656 on May 31, 2001. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates to methods and devices for releasing additives, such as disinfectants, cleaning agents, colorants, perfumes and the like into the toilet flush water, and in particular to those designed to locate within the cistern or a flush pipe of a toilet.  
         BACKGROUND OF THE INVENTION  
         [0003]    The application of additives to water flushing toilet bowls serves numerous purposes, such as cleansing, avoiding deposit of sediments, disinfecting, perfuming and even coloring of the water for aesthetic purposes. The application of such additives has long been a problem of interest in the art. An example of the efforts to solve such problems is the use of a soluble solid cake holding the required additives. The cake is immersed in the water stored in the flush water tank or cistern that is conventionally attached to the toilet bowl. The cake gradually dissolves in the water and so the additives reach the toilet bowl with every flush of the water. However, the soluble materials of the cake dissolve at a constant rate, irrespective of the frequency of the flushing of water or the duration of quiescent periods, i.e. the periods between successive flushes. Thus, the dosage of metered amount of solid additives dissolving in the water of the cistern is either impossible or requires awkward solutions. Other attempts in the prior art involve the use of liquid additives. Liquids may be rationed more easily into the water, by their manipulation within chambers, from which they are released, with the aid of means such as siphons, conduits, buoys, valves, dilution chambers and so forth. However, the viscosity of the liquid additives poses a major obstacle. Highly viscous liquids tend to clog water passages and deposit layers that cling to valves and buoys and the like and so obstruct their functioning. Low viscosity of liquids reduces dramatically the possible concentration of the additives and results with inefficient use thereof, as well as requires very large containers for the liquids. No wonder, that the user is seldom given with the capability to adjust his desired amount of additives rationed.  
           [0004]    There is thus a widely recognized need for, and it would be highly advantageous to have an in-tank dispensing device for dosing a toilet liquid additive, free of clogging problems, provides for the use of highly viscous liquid additives and that provides for user adjustable dosage capabilities.  
           [0005]    It is therefore an object of this invention to provide an in-tank dispensing device for dosing a toilet liquid additive without the disadvantages entailed with the prior art.  
           [0006]    Further objects of this invention are to provide an in-tank dispensing device for dosing a toilet liquid additive whereby the device efficiently releases rationed amounts of liquid additives into the water stored in the toilet system in each flushing cycle, irrespective of the duration of quiescent periods between flushing cycles, durable, easy to manufacture, requires mere hanging on the spot by unskilled personnel, adapted to couple to conventional toilet cisterns, allows the use of refillable container or replacement of disposable refills or provides for an entirely disposable device.  
           [0007]    These and other objects will become more apparent when viewed in light of the accompanying drawings and following detailed description.  
         SUMMARY OF THE INVENTION  
         [0008]    In its broadest aspects the present invention comprises an in-tank passive dispenser for dosing and issuing a predetermined amount of a relatively viscous, moderately soluble, having specific density heavier than water, dispensable liquid, into the cistern tank and the bowl of a flushable toilet as the flush water is draining therefrom with each flush cycle of the toilet.  
           [0009]    The dispenser is capable of varying the amount of dispensable liquid added to the toilet flush water, wherein the dispensable liquid contains additives to the flush water such as a disinfectant, a detergent, a cleaner, a stain inhibitor, a bleach, a dye, a colorant, a fragrance, a perfume, a deodorant or a compatible mixture of two or more thereof.  
           [0010]    The dispenser comprises an inverted container in which a volume of dispensable liquid is stored, the container comprises a downwardly directed discharge spout positioned on the container below the dispensable liquid level within the container and below the water level in the tank during quiescent periods intermediate flush cycles, the dispensable liquid in the container is maintained in an isolated condition from the cistern water surrounding the dispenser regardless of the depth to which the dispenser is immersed in the cistern water by the airlock created.  
           [0011]    The dispenser also features hanger means adapted to suspend the dispenser in the cistern water from an upper portion of the cistern and enabling adjustability of the position or level of the container in the cistern, preferably comprising an elongated portion having at an upper end, means to attach to an upper edge of a cistern side wall, the elongated portion being dimensioned to co-operate with a connection means on the dispenser, in a manner so as to permit the dispenser to be adjustable therealong.  
           [0012]    The hanger means may optionally comprise an elongated flat bar horizontally and removably attached to the inverted container and having a bent down portion at a first end adapted to attach to an upper edge of a cistern wall. The flat bar comprises a groove cut therealong, and the container comprises an upward projecting clasp located a the upper portion of the container, adjacent the cistern wall. The clasp comprises an Elongated portion adapted to be guided along the groove. The elongated portion comprises upper side flanges extending beyond the width of the groove for clinging the flat bar to the top of the container when the elongated portion is inserted in the groove. The the groove comprises a broadened aperture at the second end of the bar, through which aperture the clasp may be removably inserted.  
           [0013]    Further optionally, the hanger means may comprise a curving bar adapted for its affixing to the cistern wall, wherein the bar comprises a central portion curving toward the container, the central portion comprises a vertical slit open at its top and closed at its bottom, the container comprises a clasp projecting toward the cistern wall adjacent the top of the container, the clasp comprises an elongate portion adapted to be guided along the slit, and the elongate portion comprises external side flanges extending beyond the width of the slit for clinging the bar to the container when the elongated portion is inserted in the slit.  
           [0014]    The clasp may be mounted on a depressed section of the container wall for ensuring that the clasp does not protrude beyond the level of the other non-depressed section of the same container wall.  
           [0015]    Preferably, the inverted container comprises a substantially flat wall adapted to facilitate adjacent positioning against the cistern wall when the container is placed in the cistern.  
           [0016]    The dispenser further comprises a basin located below the discharge spout for receiving the predetermined amount of dispensable liquid from the container, the basin comprises basin attaching means for affixing the basin to the container wherein the discharge spout mouth is adjacently disposed above the basin floor, the basin floor is disposed above the water level of the cistern when the cistern is emptied during the flush cycle, upstanding basin side walls extending upwards above the dispensable liquid level of the predetermined amount of dispensable liquid (alternatively referred to as ‘metered amount’), and below the water level in the tank during quiescent periods, so that cistern water fill the basin above the predetermined amount of dispensable liquid during quiescent periods, and a siphon in the form of an inverted U-shaped conduit having a short stand pipe joined by a U shaped bend—extending above the level of the predetermined amount of dispensable liquid in the basin but below the water level during quiescent periods, to a long standpipe, the inlet mouth of the siphon is disposed at the lower end of the short standpipe and being immersed in the predetermined amount of dispensable liquid contained in the basin, and in fluid communication therewith, and the outlet mouth of the siphon is disposed at the lower end of the long standpipe below the bottom of the basin in fluid communication with the cistern water.  
           [0017]    The basin may also comprise discharge control means that provide for a restrained discharge of disposable liquid from the discharge spout, preferably the discharge spout comprises an externally threaded end compatibly receivable by rotary movement relative to, and within an internally threaded upstanding sleeve attached to the basin and encircling the threaded end, the sleeve comprises at least one aperture or cut-out area, the extent of exposure of which is defined by the vertical adjustment of the threaded end within the sleeve, and a surface tension moderator in the form of ribs mounted in the mouth of the discharge spout or in the form of an upright projecting from the basin floor and overlappingly penetrating the mouth of the discharge spout.  
           [0018]    Thus, on intake of flush, water and/or dispensable liquid is siphoned out of the siphon as the cistern flush water drops below the siphon outlet mouth so that the emptied siphon draws dispensable liquid from the basin, a further amount of dispensable liquid enters the basin as air penetrates said container via said discharge spout, until the water level in the cistern rises to its level during quiescent periods. Thus, the cyclic rise and fall of the cistern water results in the controlled discharge-by a siphoning action, of a rationed amount of dispensable liquid from the container.  
           [0019]    Further features and advantages of the invention will be apparent from the description below, given by way of example only. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]    The present invention will be further understood and appreciated from the following detailed description, taken in conjunction with the following enclosed drawings in which like numerals designate correspondingly analogous elements or sections throughout, and in which:  
         [0021]    [0021]FIG. 1 is a schematic side cross sectional view of one preferable embodiment constructed and operative according to the invention;  
         [0022]    [0022]FIG. 2 is a top view of a dosage basin of the embodiment shown in FIG. 1;  
         [0023]    [0023]FIG. 3 is a bottom view of an attaching means to the toilet cistern wall, of the embodiment shown in FIG. 1;  
         [0024]    [0024]FIG. 4 is a side view of a liquid container of embodiment shown in FIG. 1;  
         [0025]    [0025]FIG. 5 is a cross sectional side view of the dosage basin of FIG. 2;  
         [0026]    [0026]FIG. 6 is a cross sectional top view of a dosage basin of another preferable embodiment constructed and operative according to the invention;  
         [0027]    [0027]FIG. 7 is a cross sectional detailed side view of the embodiment of FIG. 6;  
         [0028]    [0028]FIGS. 8 a  and  8   b  are top view and side view, respectively, of an enclosure cap of the dosage basin of FIG. 6;  
         [0029]    [0029]FIG. 9 illustrates an optional surface tension moderator that may be used in conjunction with a liquid container constructed and operative in accordance with the invention;  
         [0030]    [0030]FIG. 10 is a side view of a liquid container of a further preferable embodiment constructed and operative according to the invention;  
         [0031]    [0031]FIG. 11 is a top view of the liquid container of FIG. 10;  
         [0032]    [0032]FIG. 12 is a top view of one preferable embodiment of hanger means that may be used in conjunction with the liquid container of FIG. 10;  
         [0033]    [0033]FIG. 13 is a side view of the hanging means of FIG. 12;  
         [0034]    [0034]FIG. 14 is a side view of another preferable embodiment of hanger means that may be used in conjunction with the liquid container of FIG. 10;  
         [0035]    [0035]FIG. 15 is a top view of the hanging means of FIG. 14;  
         [0036]    [0036]FIG. 16 is a partial top view of the liquid container of FIG. 10 assembled with the hanging means of FIG. 14; and  
         [0037]    [0037]FIGS. 17 a - 17   c  illustrate, in registration, a side view of a liquid container, a partially cross-sectional side view of a dosage basin, and a top cross-sectional view of the same dosage basin, of a further preferable embodiment constructed and operative according to the invention.  
         [0038]    [0038]FIGS. 18 a - 18   b ,  19   a - 19   b  depicts different views of portions of the preferred embodiment of the invention, better suited for production, but operating according to similar principles. FIG. 18 a  is a top perspective view, and FIG. 18 b  is bottom perspective view of a top portion, cooperating with a bottom portion shown in top view in FIG. 19 a  and in a cutout side view in FIG. 19 b.   
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0039]    In general, the present invention is of an in-tank passive dispenser for dosing and issuing a predetermined amount of a dispensable liquid. The term “in-tank” refers to devices that are designed to locate in the cistern tank. By the term “dispensable” reference is made to the dispensing capability of the liquid with the flush water, namely, its being soluble within water, whether as a solution or in an emulsified manner. “Dispensable” also refers to the possibility of refilling the dispenser with fresh supply of liquid, or the disposable nature of the dispenser or a container thereof that holds the liquid.  
         [0040]    The dispensable liquid is preferably relatively viscous—as characterizes a concentrated liquid for adequate effectiveness of a small amount. The dispensable liquid contains additives to the flush water such as a disinfectant, a detergent, a cleaner, a stain inhibitor, a bleach, a dye, a colorant, a fragrance, a perfume, a deodorant or a compatible mixture of two or more thereof. Preferably, the dispensable liquid is only moderately soluble and having a specific density heavier than that of water, for allowing its manipulation in the manner described below. Such requirements are not difficult to meet as most such liquids already inherently acquire the required qualities.  
         [0041]    The dispenser is designed for dosing and issuing a predetermined amount of a dispensable liquid into the cistern tank and the bowl of a flushable toilet as the flush water is draining therefrom with each flush cycle of the toilet. As will be apparent from the following description the dispenser is capable of varying the amount of dispensable liquid added to the toilet flush water.  
         [0042]    Reference is now made to FIGS.  1  to  5  in which a first embodiment of the invention is illustrated, with particular reference to a second embodiment of FIGS.  6  to  8   b , in describing the differences with respect to the first embodiment.  
         [0043]    Dispenser  1  comprises an inverted container  3  in which a volume of dispensable liquid is stored. Container  3  comprises a downwardly directed discharge spout  5  positioned on container  3  below the dispensable liquid level, such as illustrated by level  7 , within container  3 —which may vary from the top to the bottom of container  3  as more liquid is consumed therefrom. Discharge spout  5  must also be located below the water level in the tank during quiescent periods intermediate flush cycles, such as represented by level  9 -which may vary from well over the top to the bottom of container  3 , depending on its position within the cistern. The dispensable liquid in container  3  is maintained in an isolated condition from the cistern water surrounding the dispenser, regardless of the depth to which the dispenser is immersed in the cistern water by the airlock created. As will be appreciated by those skilled in the art, the air above level  7  prevents gravitational flow of the dispensable liquid from container  3 , as long as discharge spout  5  is immersed in water and thus prevents penetration of air into container  3 . Container  3  may be either refillable when emptied, or be disposable and replaceable by a full container—with or without the other parts that form dispenser  1 . Plug  10  is therefore an optional feature that seals container  3 , and is removed prior to the attachment of container  3  to the other parts of dispenser  1 .  
         [0044]    Dispenser  1  further comprises hanger means  11  adapted to suspend dispenser  1  in the cistern water from an upper portion of the cistern and preferably enabling adjusting the position or level of container  3  in the cistern. Hanger means  11  preferably comprises an elongated portion  13  having at an upper end  15  that comprises means to attach to an upper edge of a cistern side wall such as a hook or a bent edge  17 . Elongated portion  13  is dimensioned to co-operate with a connection means on the dispenser, such as open ring  19  in a manner so as to permit dispenser  1  to be adjustable therealong. Such manner may be easily achieved, for example, by a friction tight or a snap-fit engagement between ring  19  and container  3 . An optional broadened portion  21  of container may also serve as a stop means for preventing excessive sliding of container  3  from ring  19 .  
         [0045]    Dispenser  1  also comprises a deck or basin  23  located below discharge spout  5  for receiving a predetermined amount of dispensable liquid from container  3 . Basin  23  comprises basin attaching means for affixing basin  23  to container  3 , wherein discharge spout mouth  25  is adjacently disposed above the basin floor  27 . Basin floor  27  is disposed above the water level of the cistern when the cistern is emptied during the flush cycle. Preferably, discharge spout  5  comprises an externally threaded end  29  compatibly receivable by rotary movement relative to, and within an internally threaded upstanding sleeve  31  attached to basin  23  and encircling threaded end  29 . In order to provide for fine tuning capabilities of the amount of liquid discharged each flush cycle, threaded end  29  and sleeve  31  preferably comprise, in registration, relatively fine threading—allowing fine adjustment of threaded end  29  within sleeve  31 .  
         [0046]    For those skilled in the art wishing to implement the invention, it was found that the following dimensions of discharge spout  5  provide for excellent performance: height—7 mm; internal diameter—8 mm; diameter of its external threaded end—{fraction (7/16)}″.  
         [0047]    Basin  23  further comprises upstanding basin side walls  33  extending upwards above the dispensable liquid level  35  of the predetermined amount of dispensable liquid, and below the water level in the tank during quiescent periods, so that cistern water fill the basin above level  35  of the predetermined amount of dispensable liquid during quiescent periods. Since the dispensable liquid is relatively viscous, moderately soluble, and having specific density heavier than water it will remain as a lower layer in the bottom of basin  23 , with negligible amounts mixing in the surrounding water.  
         [0048]    It will be appreciated by those skilled in the art that as long as discharge spout mouth  25  is immersed in dispensable liquid in basin  35 , and as long as the dispensable liquid in basin  35  can not escape from basin  35 , no further liquid will evacuate from container  3 ; The forces of the water column above level  35  during quiescent periods, the atmospheric pressure above the water and within sealed container  3  (approximately) and the qualities of the dispensable liquid, namely—being relatively viscous, moderately soluble, and having specific density heavier than water, and the relatively narrow passage via discharge spout  25  and the gap to basin  23 , overcome the gravitational force that draws down dispensable liquid from container  3 ; The latter can provide for the drawing only during such time when such counter forces are temporarily nullified, as is achieved by the processes described below.  
         [0049]    Basin  23  further comprises a siphon  37  in the form of an inverted U-shaped conduit having a short stand pipe  39  joined by a U shaped bend  41  extending above metered amount of dispensable liquid level  35  but below the water level  9  during quiescent periods, to a long standpipe  41 . The inlet mouth  45  of siphon  37  is disposed at the lower end of short standpipe  39  and being immersed in the predetermined amount of dispensable liquid contained in the basin floor (below level  35 ) and in fluid communication therewith. The outlet mouth  47  of siphon  37  is disposed at the lower end of long standpipe  43  below the bottom  27  of basin  23  in fluid communication with the cistern water. The affixing of siphon  37  to basin  23  may be achieved by means such as clasp  44 . On intake of flush, the cistern empties rapidly, and water and/or dispensable liquid that is within siphon  37  is siphoned out of the siphon as the cistern flush water drops below the siphon outlet mouth. Thence, the pressure within emptied siphon  37  drops dramatically and thus siphon  37  draws dispensable liquid from basin  23 , in the amount predetermined according to the structure and size of siphon  37  or the amount present in basin  23 , as well as the small amount of water still in the basin  23 . Once the basin is emptied, air can freely penetrated into container  3  via discharge spout  5  and further dispensable liquid will flow into basin  23 , until the flush cycle is over and the water level therein rises again to flood basin  23 . It will be appreciated that the cyclic rise and fall of the cistern water thus results in the controlled discharge—by a siphoning action, of a rationed amount of dispensable liquid from container  3 .  
         [0050]    Preferably, basin  23  further comprises discharge control means that provide for a restrained discharge of disposable liquid from discharge spout  5 . Such control means preferably may use an externally threaded end  29  of discharge spout  5  that is compatibly receivable by rotary movement relative to, and within an internally threaded upstanding sleeve  31  that is attached to basin  23  and encircles threaded end  29 , as already explained above. Sleeve  31  preferably comprises at least one aperture or cut-out area  49 , the extent of exposure of which is defined by the vertical adjustment of threaded end  29  within sleeve  31 .  
         [0051]    Due to excessive viscosity the smooth streaming of dispensable liquid through discharge spout  5  and area  49  may be hampered. An optional surface tension moderator in the form of an upright  51  that projects from basin floor  27  and overlappingly penetrates the mouth  25  of discharge spout  5  can relieve such hindrance.  
         [0052]    Another example of surface tension moderator may be in the form of ribs mounted on the mouth of discharge spout  5 , such as ribs  53  illustrated in FIG. 9. Ribs  53  preferably comprise upper sharp edges  55  for facing the dispensable liquid when incoming from container  3 . Sharp edges enhance the tension moderating character of the ribs. Ribs  53  may be in the form of a cross shaped moderator, as in FIG. 9, but it will be appreciated that many variations of such form may be well suited for this function.  
         [0053]    Referring now to FIGS.  6  to  8   b , another embodiment of the present invention is shown. This embodiment is a compact, easy to manufacture, variation of the embodiment of FIGS.  1  to  5 . Discharge spout  5  is inserted in a similar manner into ring  131  that features an opening  149  through which dispensable liquid flows on basin floor  127  of basin  123 . Basin  123  comprises two conduits—a short conduit  139  with a closed bottom, and a long conduit  143  extending through basin floor  127  and having its outlet mouth  147  below basin floor  127 . Conduits  139  and  143  may be drilled in a solid portion of basin  123  for ease of manufacture. An upper passage  141  connects the upper portions of conduits  139  and  143 . A passage  155  connects the inner hollow parts of basin  123  to conduit  139 . An enclosure and sealing element  157  completes the structure of basin  123 . Element  157  has an L-shaped cross-section and comprises a roofing portion  159  and a side potion  161 . Portion  159  conceals, in a substantially water tight manner the upper portion of chunk  153  and thus forms an upper roof to passages  141  and  155 , and conduits  139  and  143 . Portion  161  partially covers passage  155 , but its main function is to hold portion  159  in place. Element  157  is disposed in place by inserting portion  161  through guiding rails  163  that are carved on walls  133  between chunk  153  and projections  165 .  
         [0054]    Reference is now made to FIGS.  10  to  16  in which further alternate embodiments of container  3  and hanger means are presented. Hanger means in FIGS.  10 - 13  comprise an elongated flat bar  201  removably horizontally attachable to inverted container  3  and having a downward bent portion  203  at its first end  205 , adapted to attach to an upper edge  207  of a cistern wall. Flat bar  201  comprises a groove  209  cut therealong. Container  3  comprises a clasp  211  projecting upwards on the top portion of the container, adjacent the cistern wall  207 . Clasp  211  comprises an elongate portion  213  adapted to be guided along groove  209 . Elongated portion  213  comprises upper side flanges  215  extending beyond the width of groove  209  for clinging flat bar  201  to the top of container  3  when elongated portion  213  is inserted in groove  209 . Groove  209  comprises a broadened aperture  217  at the second end  219  of bar  201 , through which aperture  217  clasp  211  may be removably inserted. Bar  201  may be adjusted along elongated portion  213  in a friction tight manner to firmly grip cistern wall  207 , and released whenever removal of container  3  is desired.  
         [0055]    A further alternate embodiment of hanger means  11  is shown in FIGS.  10  to  11  and  14  to  16 . Hanger means  11  further comprise a curving bar  221  adapted to be fixed to cistern wall  207 , by any known manner, such as by the permanent bonding, riveting or fastening of lateral ears  222  to the cistern wall  207 . Bar  221  comprises a central portion  223  curving toward container  3 , and central portion  223  comprises a vertical slit  225  open at the top  227  and closed at the bottom  229 . Container  3  comprises a clasp  231  projecting toward cistern wall  207  adjacent the top of container  3 . Clasp  231  comprises an elongated portion  233  adapted to be guided along slit  225 . Elongated Portion  233  comprises external side flanges  227  extending beyond the width of slit  225  in curving bar  221  to support container  3  when elongated portion  233  is inserted in slit  225 .  
         [0056]    Preferably, clasps  211  or  231  are mounted on a depressed section  235  or  237 , correspondingly, of the wall of container  3  to ensure that clasp  211  or  231  does not protrude beyond the level of the other non-depressed section  239  or  241 , correspondingly, of the same wall of container  3 . Such configuration ensures that clasps  211  and  231  do not interfere with the contiguous attachment of container  3  to cistern wall  207  or its juxtaposing to upper cover of the cistern (not shown). Container  3  further preferably comprises a substantially flat wall  241  adapted to be contiguously positioned against cistern wall  207  when container  3  is placed the cistern, to eliminate movement and to stabilize container  3  while the cistern water turmoil.  
         [0057]    In reference to FIGS. 17 a  to  17   c , a further embodiment of the present invention is shown. This embodiment is a further variation of the embodiment of FIGS.  1  to  5  and is particularly similar to that shown in FIGS.  6  to  8   b . The main difference being in the addition of an intermediate conduit, such as a flexible plastic pipe  301 , between liquid container  3  and basin  323 . The addition of pipe  301  allows the mounting of liquid container  3  remotely from basin  323 . The separation between container  3  and basin  323  provides, among others, for positioning container  3  outside the cistern. This configuration saves the need to hang dispenser  1  in its entirety within the cistern. Some flushing tanks may pose a difficulty for the insertion, placing or hanging of container  3  there within. This is the case when there is lack of sufficient clearance from the flushing mechanism inside the tank or when opening and closing of the tank-cover is inconvenient. Moreover, basin  323  may be made small enough to permit installation in the flushing conduits rather than in the tank itself. In such a case the specific weight or density of the dispensing liquid need not be heavier than that of water.  
         [0058]    Discharge spout  5  is inserted in a similar manner into adapter ring  310  that features an extended conduit  311  that can be water-tightly inserted into the end of pipe  301 .  
         [0059]    The other end of pipe  301  is similarly tightened to an extended conduit  335  of ring  330  that is in fluid communication with opening  349 , through which dispensable liquid flows on basin floor  327 . Ring  330  may preferably feature adjusting capabilities allowing adjustment of its height above basin floor  327 . Such capabilities allow calibrating the degree of exposure of opening  349 , thence regulating the rate of flow and eventually the amount of dispensable liquid released therefrom with each flush cycle.  
         [0060]    For example, extended conduit  335  may comprise an externally threaded portion  329  compatibly receivable by rotary movement relative to, and within an internally threaded ring  330  encircling threaded portion  329 . In order to provide for fine tuning capabilities of the amount of liquid discharged each flush cycle, threaded end  29  and sleeve  31  preferably comprise, in registration, relatively fine threading allowing fine adjustment of threaded end  329  within ring  31 . An alternate flow calibration control may be provided by an externally threaded end  329 ′ of conduit  335  that is compatibly receivable by rotary movement relative to and within an internally threaded upstanding apertured sleeve  331 . Sleeve  331  is attached to basin  23  and encircles threaded end  329 ′, save its cut out aperture  349 . The operation of such structure is corresponding to what has been explained above.  
         [0061]    Basin  323  comprises two conduits—a short conduit  339  with a closed bottom, and a long conduit  343  extending through basin floor  127  and having its outlet mouth  147  below basin floor  327 . Conduits  339  and  343  may be drilled in a solid portion of basin  323  for ease of manufacture. An upper passage  341  connects the upper portions of conduits  339  and  343 . A passage  363  connects the inner hollow parts of basin  323  to conduit  339 . An enclosure and sealing element  357  completes the structure of basin  323 . Element  357  has an L-shaped cross-section and comprises a roofing portion  359  and a side potion  361 . Portion  359  conceals, and substantially makes watertight, the upper side of passages  341 , and conduits  339  and  343 . Portion  361  partially covers passage  363  but its main finction is to hold portion  359  intact in place. Element  357  is held in place by inserting portion  361  through guiding rails  363  that are carved on walls  333 .  
         [0062]    While the invention has been described with respect to specific embodiments, it will be appreciated that many variations, modifications and other applications of the invention may be made.  
         [0063]    With the foregoing description, it is believed apparent that the present invention enables the attainment of the objects initially set forth herein.  
         [0064]    It should be understood, however, that the invention is not intended to be limited to the specifics of the illustrated embodiment, but rather is defined by the accompanying claims.

Summary:
A dispenser for dispensing metered amount of liquid into a toilet cistern, comprising a basin adapted to receive a metered amount of dispensable liquid received from a container via a discharge spout. An airlock prevents further discharge of a liquid above a predetermined amount in the basin when the discharge spout is covered vy the dispensable liquid. A siphon inlet is in liquid communication with the metered amount in the basin, and the siphon outlet is in liquid communications with the cistern water at quiescent times. Upon flush, the siphon siphons out the dispensable liquid in the basin, breaking the airlock, and allowing a new metered amount of dispensable liquid to flow to the basin, ready for the next flush.