It is a common characteristic of most hitherto known cistern flush assemblies that between a closure member altering the flow passage of the inlet valve and moveable between end positions associated with an open and a closed valve state, respectively, and a float which moves in the cistern along with the water level at least in certain phases of the water level fluctuation, a co-acting positive mechanical coupling is provided for. A known flush assembly of the kind indicated is described, for example, in the US Patent No. 5,062,751, where a float is secured to the end of a longer arm of a single-arm lever capable of tilting around a fulcrum secured to a valve housing, and the closure member of the valve is assigned to the end of a shorter arm of the single-arm lever in a way that an upper end of the closure member is permanently biassed by the pressure of water flowing across the valve against the lever, and the lever is driven, in both directions, between its two end positions by a float. As a result, it is a major disadvantage of the known flush assembly referred to, but also that of all such types of flush assemblies, for example the one described in the US Patent No. 5,119,845, that during the re-filling of the receptacle after discharge, the movement of the closure member in the closing direction of the valve slows down gradually and proportionally with the gradually slowing rate of the rise of the float. Thus, the time period needed for filling or re-filling the flush water cistern is extremely long, and the closure member of the valve gradually narrowing the flow passage of the valve over such long periods of time as well as the co- acting valve seat are subject to rapid wear.

Published European patent application No. EP 0 704 581 A2 describes a more advanced toilet flush assembly where-when the flush valve is opened to flush the cistern-the inlet valve is also opened simultaneously through a lever and a gear machanism. In addition, in an alternative mode of operation, the toilet flush assembly is also suitable for a so-called spare flush mode of operation using a smaller volume of water than that stored in the cistern for full volume flushing. The known toilet flush assembly furthermore has a perforated float which filles up with water during the filling of the cistern and is able to discharge the water contained therein within a specified period of time. Such a float prevents the automatic refilling of a cistern from which the water escapes slowly and continuously as a result of a sealing problem. Since, however, a positive mechanical coupling is present between the closure member of the inlet valve and the float gradually rising in the course of filling up, also for the operation of this well known toilet flush assembly applies that the movement of the closure member of the inlet valve-when filling up or in the course of refilling the cistern after discharge- gradually slows down proportionally with the gradually slowing rise of the float, and so the time needed to fill up the cistern is extremely long.

Summary of the Invention An abject of the present invention is to provide a cistern assembly for flush toilets which-especially in the light of the long fill-up time characterising the known assemblies of the kind concerned-enables the refilling of the cistern in a considerably shorter time.

A further object of the invention is to provide an improved cistern assembly for flush toilets suitable for performing a spare flush mode of operation.

Another object of the present invention is to provide a cistern assembly for flush toilets which, similarly to the approach described in EP 0 704 581 A2, is capable of detecting a sealing failure present in and leading to water escaping continuously from the system, and preventing the automatic refilling of such cisterns after their being discharged, while still permitting single flushings of the toilet, if required.

A general object of the invention is to create a quiet operation, long life cistern assembly for flush toilets allowing within wide limits, the possible selection of the dynamic characteristics of the moving parts comprised therein and thus, exhibiting an improved operational reliability.

The above and further objects are accomplished by the provision of an improved cistern assembly for flush toilets having the features listed further above in the introductory paragraph of the present description, and which is characterised, according to the new and decisive characteristic feature of the invention, by having an inlet valve comprising, between the closure member and the balance lever, a toggle switch mechanism capable of moving the closure member of the inlet valve between its end positions when pre-determined threshold values of the torque exerted by the float on the balance lever are reached at, or exceeded.

The inlet valve of the cistern assembly for flush toilets of the invention having a toggle switch mechanism that moves the closure member of the inlet valve between its end positions opens the valve very quickly, practically immediately to its full flow cross section at the time when the water level starts to drop upon opening the flush valve. The inlet valve starts to fill up the cistern with the highest possible rate of flow. As a result of this quick operation, the inlet valve is able to supply already during the open position of the flush valve, additional flush water volume to the water quantity stored in the cistern, and for the single discharge of the same volume of flush water it is sufficient to store less water in the cistern than in conventional toilet flush assemblies. Alternatively, the invention renders possible to use much smaller volume cisterns than in the well known designs. On the other hand, however, after completion of the water discharge when the flush valve returns to its closed position and the water level in the cistern starts to rise rapidly, the inlet valve remains open for full flow as long as the torque exerted on the balance lever of the inlet valve by the float-which gradually loses its weight by being immersed into water and which also exerts, provided that a convenient design is applied, buoyant force on the balance lever-reaches or its decrease exceeds the threshold rate of the toggle switch mechanism required for swithing the valve back into its closed state.

Consequently, contrary to well known toilet flush assemblies, the flow section of the inlet valve is not narrowing during the time when the water level rises, but it practically remains constant until the last moment of filling, as a result of which the refilling of the cistern is completed within the shortest possible period of time.

In preferred embodiments of the cistern assembly of the present invention the float comprises at least two space portions of different densities, where one of the space portions is of a density lower than that of the water, while the density of at least another space portion of the float is at least identical with or preferably higher than that of the water, and the space portion of lower density is located in the range above the higher density space portion of the float. The float is coupled with the balance lever of the inlet valve by a linkage suitable for transferring load in both directions. In a first commercial implementation of the invention, the inlet valves and floats of well known conventional toilet flush assemblies that are in use currently may be replaced, by retaining the cistern and the discharge valve, by a combination of an inlet valve incorporating a toggle switch mechanism and and a float having the features listed further above. In the cistern being discharged during flushing, the float will gradually become"left in the dry", and it is no longer subjected to the buoyant force. Following this, the force of gravity, i. e. the weight of the float increases gradually. When the torque exerted by the force of gravity of the float on the balance lever of the inlet valve reaches the pre-determined threshold value necessary for reversing the toggle switch mechanism of the inlet valve, the inlet valve opens to full flow, and a rapid refilling of the cistern commences. In the meantime, the flush valve of the cistern closes, and the water level of the cistern rises rapidly, while the float becomes immersed in water, gradually. At the beginning, in its floating condition the float loses its force of gravity and then the buoyant force starts to act on the float as well. As a result of the latter, the torque exerted on the balance lever of the inlet valve reaches and exceeds the threshold value again, and it moves the inlet valve into its closed valve state, whereby the flow of water therethrough is stopped, and the cistern assembly is ready again for repeated flushing.

In preferred embodiments of the cistern assembly of the invention the float or at least one of its space portions is designed so as to form a float of varying weight by being filled up, at least temporarily and at least partially, with water. The float is designed preferably as an at least partially hollow body having an inner space capable of communication with its environment through perforations. Alternatively, the float may also have the shape of an open top vessel featuring a bottom part provided with at least one perforation. Improved reliability of the reversal of the inlet valve into its closed state can be achieved by using in the cistern assembly according to the present invention a float that is designed and shaped as an at least two-part combined float comprising an upper closing float of a density lower than that of the water and a lower opening float.

The closing float is connected to the balance lever of the inlet valve in an adjustable height position relative to the cistern in a way suitable for transmitting forces in both directions, while the opening float may be connected to the same through a preferably flexible link suitable for transferring to the balance lever at least the actual weight load of the opening float. The floats representing separate component parts of the combined float well determined functions can be assigned to. The separate closing float can be freely dimensioned. On the one hand, it ensures through its buoyant force a reliable closing of the inlet valve. On the other hand, its adjustability in height provides a simple opportunity to pre-determine the prescribed water level of the cistern, and to change this when desired. The use of a separate opening float at the same time offers further wide opportunities for implementing structural approaches serving to achieve further objectives of the invention, mentioned above.

In order to avoid extensive water losses caused by leaking systems, it is an essential requirement to prevent the automatic refilling of cisterns from which the water escapes relatively slowly and continuously due to a sealing failure. This requirement can be met by using embodiments of the present invention in which the opening float is designed, e. g. as an open top vessel having a bottom part comprising at least one perforation, the opening float having optionally, at least one choking or closure member, especially a closing disc arraged in the vessel. The choking or closure member provides a check valve capable of choking or closing the perforation (s) in the outlet direction of flow from the vessel.

The opening float immersed in water in the filled up condition of the cistern and thus, filled with water, becomes"left in the dry"in the course of the rapid drop of the water level in the cistern which occurs at normal flushing. Since the float includes retained water, it has sufficient weight to drive by its force of gravity the toggle switch mechanism of the inlet valve into its open valve state, whereby the refilling of the cistern is initiated automatically. However, in case of a slow drop of the water level as a result of a sealing failure in the system, a sufficiently long period of time is provided for allowing the water to escape from the float through the drain holes of the bottom part thereof. The remaining force of gravity of the empty float will no longer be sufficient to move the toggle switch mechanism of the inlet valve to the open valve state.

Consequently, a slowly emptied cistern will not be automatically refilled. At the same time, the cistern can be refilled as necessary to a state ready for re-flushing, preferably by external actuation of the balance lever of the inlet valve. The non-performance of automatic refilling, however, warns the user or operator that in the system there is probably a sealing defect that should be eliminated.

Increased reliability of the operation of the inlet valve in both directions can be achieved by using, between the closure member of the inlet valve and the balance lever, a toggle mechanism that is designed as an energy-storing mechanism which includes at least one pre-tensioned spring member.

In preferred embodiments of the present invention the use of inlet valves has proved to be of advantage, in which the mechanism arranged between the closure member and the balance lever of the inlet valve is desioned as a toggle switch mechanism capable of driving the closure member from its end position corresponding to the closed state of the inlet valve to its other end position corresponding to the open state of the inlet valve by an increased torque only, which increased torque is to be exerted on the balance lever by an external force to be added additionally and temporarily, to the force of gravity of the float. In such embodiments, the opening of the valve only occurs upon an"external command", an additional opening force acting on the balance lever of the inlet valve and exerted preferably, simultaneously with the opening actuation of the flush valve. In such embodiments of the invention it is an advantage that the operation of the cistern assembly becomes significantly quicker because for opening the valve it is not necessary to wait for a certain drop of the water level in the cistern. The intensity of flushing is also improved, and the requirement of preventing the automatic refilling of systems having a sealing problem can also be met at the same time.

In embodiments of the cistern assembly for flush toilets of the invention in which filling up of the cistern only starts upon an"external command", for initiating the flush mode of operation of the cistern assembly by opening the flush valve the use a flush device has proved to be advantageous which flush device comprises a double-arm lever pivoted in a tiltable way around a fixed fulcrum and at least one manual actuator that is assigned to a first arm of the said double-arm lever, while a second other arm of the double-arm lever is connected to the flush valve. The first arm of the double-arm lever has a driving tongue capable of driving the balance lever and thereby the closure member of the inlet valve from its end position corresponding to the closed state of the inlet valve to its other end position corresponding to the open state of the inlet valve.

Preferred embodiments of the cistern assembly of the invention capable of performing flushing with different volumes of water, especially a spare flush with a low quantity of water and a normal flush with full water volume, are equipped with a flush device which comprises alternative manual actuators associated with the first arm of the double-arm lever. The manual actuators are acting on the first arm at different distances from the fixed fulcrum by being arranged on opposite ends of a two-arm rocker, whereby upon respective actuations, different extents of lever swivel are performed on the first arm. Alternatively, one of the manual actuators may be designed as a push button of delayed effect which when actuated, abuts on the first arm after a stroke displacement of specified extent only.

Improved reliability and lifetime of the cistern assembly according to the invention can be achieved by designing and using embodiments comprising at least one float capable of influencing the dynamic characteristics of the operation of the inlet valve, especially the acceleration and the speed of the closure member during its movement between its respective end positions. Such at least one float may comprise a surface member which increases the flow resistance of the float in the water when the float is moving or moved in vertical direction. The float may include or consist, at least partially, of vertically spaced horizontal segments.

In further preferred embodiments of the invention a filling pipe is connected to the outlet chamber of the inlet valve and the filling pipe comprises means, especially a check valve for preventing the return flow of water from the cistern through the inlet valve in case of a pressure drop, especially if vacuum appears in the water supply means.

The means for preventing the return of water from the cistern through the inlet valve, especially said check valve preferably includes a sound reducing means for reducing the noises generated by the flow of water when filling the cistern.

By appropriate and suitable design and dimensioning of the various sub- assemblies, especially the inlet valve and its toggle switch mechanism, as well as the float and the flush valve initiating the emptying of the cistern, and by chosing advantageous combinations of various characteristics, the cistern assembly for flush toilets of the invention enables a very wide variety of particular designs and applications.

Depending on actual requirements, the cistern assembly can be designed and operated as an automatically refilling device, as a device refilling upon external command only, or as a device in which the cistern is not refilled in the case of a system defect caused by leakage or a sealing failure.

Brief Description of the Drawings Other features and advantages of the cistern assembly for flush toilets according to the present invention will become apparent from the following detailed description of preferred embodiments with reference to the accompanying drawings, of which Fig. 1 is a skech depicting by way of example only the schematic design of a first embodiment of the invention, Figs. 2A and 2B are sectional and elevational views of a first embodiment of an inlet valve of the cistern assembly of the invention, Figs. 3A and 3B are elevational sketches of a second embodiment of the inlet valve of the cistern assembly of the invention, Figs. 4A and 4B are sectional and elevational views of a third embodiment the inlet valve of the cistern assembly of the invention, Figs. 5A-5C are sketches depicting by way of example only, the cistern assembly of the invention in three characteristic modes of operation, Fig. 6 is a sketch showing as a special detail and by way of example only, an alternative design of the flush device actuator, Figs. 7A-7D are a series of sketches depicting as a first example, an embodiment and the operation of a combined float, Figs. 8A-8F are a series of sketches depicting as a second example, another embodiment and the operation of a combined float, Figs. 9A-9F are sketches depicting a further embodiment and the operation of a combined float, Fig. 10 depicts an alternative design of the combined float, Fig. 11 is the sketch of a further embodiment of a float comprising segments as an example only, Figs. 12A-12C are a series of sketches depicting by way of example only, an embodiment of a check valve and its operation which prevents the return flow of water to the mains through the inlet valve, Fig. 13 depicts by way of example, an alternative embodiment of the check valve for the assembly that prevents the return flow of water to the mains through the inlet valve, while Figs. 14A and 14B are elevational sketches of a further embodiment of the inlet valve of the cistern assembly of the invention, as a further example.

Modes for Carrying Out the Invention The schematic diagram of Fig. 1 shows a cistern assembly embodying the invention, which includes a cistern 1, an inlet valve 2 controlled by a float 3, a flush valve 5 assigned to a bottom flush outlet 10 of the cistern 1, as well as flush device 6 by which the flush mode of operation of the assembly, i. e. the emptying of the cistern 1 by opening the flush valve 5 is to be initiated. The float 3 is connected to a balance lever 20 of the inlet valve 2. The flush device 6 comprises a double-arm lever 60 pivoted in a tiltable way, around a fixed fulcrum 63, and a manual actuator 65 is assigned to a first arm 61 of the double-arm lever 60, while a second arm 62 of the double-arm lever 60 is connected to the flush valve 5. The inlet valve 2 shown in Figs. 2A and 2B of the cistern assembly embodying the invention has a pressure chamber 21 and an outlet chamber 22, between which a flow passage 23 of relatively large cross section is located. A closure member 24 arranged in the pressure chamber 21 is assigned to the flow passage 23. The closure member 24 is linearly moveable between two end positions corresponding, respectively, to a closed and an open valve state of the inlet valve 2. According to a novel characteristic feature of the invention, a toggle switch mechanism 4 moving the closure member 24 from one of its end positions to its other end position in both directions is arranged between the closure member 24 and the balance lever 20. The closure member 24 is moved from one position to the other when during operation, pre- determined threshold rates of the torque exerted on the balance lever 20 by the force of gravity of the float 3 and/or the buoyant force are reached at or exceeded. The force of gravity of the float 3 changes depending on the water level WL prevailing in the cistern 1. In Fig. 2A, the float 3 is in a position above a specified water level WL of the cistern 1, and so the torque of its full weight acts on the balance lever 20. The inlet valve 2 is in its open thoroughfare state, and the water flowing across the inlet valve 2 fills up the cistern 1 (not shown), with its water level WL rising gradually. In the state of the inlet valve 2 shown in Fig. 2B, when reaching the prescribed water level WL, the float 3 has lost its weight as a result of being at least partially, immersed in water. The torque which has kept the closure member 24 of the inlet valve 2 in its end position corresponding to the open state of the valve has decreased, and the toggle switch mechanism 4 inserted between the balance lever 20 and the closure member 24 has been moved to its other end position whereby the closure member 24 has been moved into its end position in which it closes, in a water-tight manner, the flow passage 23 of the inlet valve 2. In this embodiment, the toggle switch mechanism 4 also comprises an energy storing spring member 41 which helps to facilitate the driving of the mechanism between its end positions in both directions.

When in operation, in the cistern assembly of the invention comprising an inlet valve 2 associated with a toggle switch mechanism 4 driving the closure member 24 of the inlet valve 2 between its end positions, the inlet valve 2 opens very quickly, in fact immediately to its total flow section when as a result of opening the flush valve 5, the drop of the water level commences, and the pre-determined threshold value of the torque necessary for opening of the valve is exceeded. Thus, the refilling of the cistern 1 is started with the highest possible supply flow of water. As a result of this, the inlet valve 2 is able to replenish the water stored in the cistern 1 with additional flush water volume even while the flush valve 5 is still open. Consequently, for a single delivery of a prescribed volume of flush water it is sufficient to store a lower water volume in the cistern 1 than with conventional toilet flushing assemblies, or is possible to use a much smaller volume cistern 1. When flushing of the toilet is completed, that is when the flush valve 5 returns to its closed position and the water level WL in the cistern I starts to rise rapidly, in the course of its becoming immersed in water the float 3 will gradually lose its weight. The inlet valve 2 is however, kept open for the full flow rate of water flow as long as the torque exerted on the balance lever 20 by the float 3 reaches, or its reduction exceeds the pre-determined threshold value necessary for the toggle switch mechanism 4 to be reversed. Consequently, and contrary to known toilet flush assemblies, the thoroughfare cross section of the inlet valve 2 will not decrease gradually while the water level WL in the cistern 1 rises, but it remains constant until the last moment of fill-up.

As a result of this, the refilling of the cistern 1 is completed within the shortest possible time.

Especially in the field of precision engineering, toggle switch mechanisms are well known in numerous designs, and the most diverse actual embodiments of the same can be adapted to and used in the inlet valve 2 of the cistern assembly according to the invention. By way of example only, Figs. 2A and 2B show a toggle switch mechanism 4 comprising a coupling link 40 and a pre-tensioned spring member 41 as already referred to further above. It is important to note, however, that it is not absolutely necessary to use a spring member 41 in the toggle switch mechanism 4, because the water pressure acting against the closure member 24 of the inlet valve 2 provided that the latter is appropriately dimensioned and coupled, as an option, with a so-called combined float 3, may be sufficient on its own, to perform the role of an energy-storing member of the toggle switch mechanism 4.

Figs. 3A and 3B show as an elevation and in the open and closed state of the valve, respectively, an inlet valve 2 having a different design of the toggle switch mechanism 4. In this embodiment, a combined float 3 is arranged on a sleeve 28 that is slidably guided along a filling pipe 25 of the inlet valve 2. An upper portion of the combined float 3 is of a density which is lower than that of the water. When immersed in water, said upper portion of the combined float 3 acts with its buoyant force via a coupling rod 29 against the balance lever 20 of the inlet valve 2 and the latter is moved into its closed valve state when the pre-determined threshold value of the torque exercised thereby on said balance lever 20 is exceeded. A lower portion of the combined float 3 is of higher density than that of the water. When upon flushing, i. e. emptying the cistern it becomes no longer immersed in water, its full force of gravity will act on the balance lever 20 and the torque generated thereby will be sufficient to initiate the movement of the inlet valve 2 into its open state of operation.

As a further example, Figs. 4A and 4B of the attached drawing depict in its respective thoroughfare and closed valve state again, an inlet valve 2 comprising in addition to the spring member 41 assigned to the closure member 24, another additional spring member 42. This embodiment of the inlet valve 2 is at least within a certain range, capable of detecting and compensating changes in the mains water pressure, and in the open valve state the actual position of the closure member 24 will depend on the current, actual water pressure. Thereby, the flow of water passing the inlet valve 2 will remain substantially constant, at least between determined limits of varying means pressure.

By suitably designing and dimensioning the toggle switch mechanism 4 and the float 3 connected to the balance lever 20 of the inlet valve 2, advantageous and optimum operating conditions and modes of operation of the cistern assembly embodying the invention can be performed. In Fig. 1 of the attached drawing a very simple cistern assembly embodying the invention is shown. In this embodiment, the inlet valve of a conventional toilet flush assembly has simply been replaced by an inlet valve 2 comprising a toggle switch mechanism 4. The assembly shows the already mentioned significant benefit of an extremely short time period needed for refilling the cistern 1. In this embodiment, the inlet valve 2 and the associated float 3 are designed and dimensioned so that subject to the changes in water level, the float 3 is on its own able to initiate the movement of the toggle switch mechanism 4 of the inlet valve 2 in both directions.

Figs. 5A-5C of the attached drawing show by way of example another embodiment of the cistern assembly of the invention where the toggle switch mechanism 4 will move the inlet valve 2 from its closed valve state to the open valve position only if an additional external force exerted on balance lever 20 is added to the force of gravity of the float 3. To this end, the first arm 61 of the double-arm lever 60 of the flush device 6 has a driving tongue 64 for helping to initiate the movement of the balance lever 20 of the inlet valve 2 from its closed valve state end position into its other end position corresponding to the open state of the inlet valve 2. This embodiment is also suitable for implementing a so-called spare flush mode of operation of the cistern assembly, because the flush device 6 comprises two actuators 65,66 associated both with the first arm 61 of the double-arm lever 60. Said actuators 65 and 66 provide for alternative swivels of the double-arm lever 60 of different extent. The actuators 65 and 66 are arranged at opposite ends of a double-arm rocker 67. When actuated, said ends act at locations of different distances from the fulcrum 63 on the first arm 61. In a first state of operation shown in Fig. 5A, the cistern 1 is filled up with water to the prescribed, desired extent, while both the inlet valve 2 and the flush valve 5 are in their closed positions. For implementing the spare flush mode of operation of the cistern assembly using just a low volume of water, the actuator 66 on the left hand side end of the rocker 67 is depressed as shown in Fig.

5B. In this case the double-arm lever 60 is swivelled to a small extent only, the driving tongue 64 has hit against the balance lever 20 of the inlet valve 2 whereby it has been duly helped to switch over to its open valve state position, and a bell shaped member 50 <BR> <BR> <BR> of the flush valve 5 has been raised by a small stroke h. Thereby, a low flow rate of flushing water has been allowed for which is unable to maintain this only slightly raised stroke position of the flush valve 5. Thus, when releasing the actuator 66, the flush valve 5 returns to its closed position, and the low volume flushing is completed. For flushing with the total water quantity, in the way shown in Fig. 5C, the actuator 65 on the right hand side end of the rocker 67 is depressed. As a result of this, the double-arm lever 60 performs a larger angular swivel, at the beginning of which the driving tongue 64 hits the balance lever 20, driving over and opening the inlet valve 2. The bell shaped member 50 of the flush valve 5 opens, however, to its full stroke H. The differential pressure arising as a result of the high rate of water flow leaving the cistern 1 through the flush outlet 10, combined with the buoyant force of a float (not shown in the drawing) associated with the bell shaped member 50 will maintain the open state of the flush valve 5 until the full volume of water leaves the cistern 1. Then, the flush valve 5 closes, and since the inlet valve 2 has already been moved to ist open state, the water level WL in the cistern 1 will rise rapidly. The float 3 will immerse in the water and lose its weight, gradually. The torque acting on the balance lever will follow the reduction of weight of the float 3, and when the pre-determined threshold value of the torque is reached at, the toggle switch mechanism 4 returns the closure member 24 of the inlet valve 2 to its valve closing position, whereby the cistern assembly is reset to its normal position shown in Fig. 5A, in which the assembly is again ready for both, its spare and full flush mode of operation.

Fig. 6 depicts as an elevation, an alternative design for manually operating the flush device 6. In this case the actuator initiating the spare flush mode of operation is designed as a push button 68 acting on the first arm 61 of the double-arm lever 60 with some delay, i. e. after a stroke displacement of a certain extent only. If flushing is initiated by depressing the push button 68, the push button 68 initially carries out an "idle"stroke and is displaced against a soft reset spring 69 only. Its further displacement swivels the double arm lever 60 slightly, which in turn opens the flush valve 5 by raising the bell shaped member 50 of the flush valve 5 by the slight stroke h only, as described above with reference to Fig. 5B. Consequently, the cistern assembly of the invention carries out a spare flush using a small volume of water. For flushing with the total volume of water stored in the cistern 1, the actuator 65 acting on the first arm 61 of the double-arm lever 60 as indicated by an arrow in Fig. 6, is to be depressed, as a result of which the double-arm lever 60 carries out a full stoke swivel, the bell shaped member 50 of the flush valve 5 opens to full stroke H, after the driving tongue 64 initiated the switch-over of the toggle switch mechanism 4 to the open valve state of the inlet valve 2 by having hit the balance lever 20. For the rest of the full flush mode of operation and the resetting of the assembly to its condition ready for consecutive flushings, reference is made to what has already been described with reference to Fig. 5C further above.

It has already been mentioned earlier that the inlet valve 2 comprising a toggle switch mechanism 4 according to the invention will only switch over from one valve position to the other when pre-determined threshold values of the torque acting on the balance lever 20 are reached at or exceeded. One decisive component of the torque acting on the balance lever 20 is the weight of the float 3, which changes depending on whether the float 3 is partly or fully in or out of the water. In addition to this however, the change of weight can largely be influenced by appropriately selecting the structural materials of, and by designing the float 3 in a proper way. On the basis of and by making use of this recognition, by using at least one float of varying weight, embodiments of the cistern assembly of the present invention can be developed by which an empty cistern 1 is not re-filled automatically, if the water escaped from the cistern 1 slowly and on an ongoing basis due to failure or contamination of the flush valve 5 or other reason, whereby continuous loss of water would arise even when the assembly is not used. Such embodiments of the cistern assembly of the invention can be implemented, for example, by using appropriate and advantageous designs of the float 3 to be described by way of example only, further below.

A thin-wall float 3 of in the given case spherical shape and of varying weight is shown in its various operating conditions in Figs. 7A-7D of the attached drawing. The float 3 fixed in a way adjustable in vertical direction to a substantially rigid rod 38 suitable for transmitting force in both directions. In the bottom range of its spherical wall, the float 3 has perforations 32 and at least one perforation 32 is also provided in the upper range of the spherical wall, in order to let the inner space of the float 3 communicate with the surrounding environment. The float 3 is coupled to the rod 38 by means of a drawn-in upper neck portion 33, which protrudes into the inner space of the float 3 virtually as a siphon, up to the height of the upper perforation (s) 32. In the state of operation shown in Fig. 7A, the float 3 is staying in the space above the water level of cistern 1 (not shown in the drawing) and its inner space is filled up with air. While the water level WL of the cistern 1 rises, the float 3 gradually immerses in water (Fig. 7B), and the inner space of the float 3 gradually filles up with water through the lower perforations 32 until the water reaches the upper perforation (s) 32 (Fig. 7C). When the water level WL further rises above the latter, air is trapped in the space portion 39 confined by the siphon-like neck portion 33 in the inner space. In this state of operation of the float 3, in addition to the reduction of weight resulting from the loss of weight, a buoyant force will act on the float 3, too. Such a design of a float is called a combined float. When the water level WL of the cistern 1 quickly drops as a result of normal flushing, water will be retained in the inner space of the float 3, since the cross section choke effect of the bottom perforations 32 allows for a slow escape of the water only.

Therefore, the weight of the float 3 which is still filled up, at least partially, with water and staying above the water level WL, is sufficiently large to exert on the balance lever 20 of the inlet valve 2 a torque exceeding the threshold value, necessary for driving the toggle switch mechanism 4 into its open valve position and thus, the cistern 1 will be re- filled with water automatically.

However, when as a result of a sealing failure the water level WL of the cistern 1 decreases slowly, the float 3 is emptied simultaneously with the dropping of the water level WL. The low weight of the empty, thin-wall float 3 exerts a torque on the balance lever 20 of the inlet valve 2 that is lower than the threshold value of the torque needed for opening the inlet valve 2. Consequently, no automatic refilling of the cistern 1 will occur, and a continuous loss of water is prevented. Such embodiments of the cistern assembly of the invention do, however, not prevent the flushing of the toilet as necessary, because the driving tongue 64 of the double-arm lever 60 of the flush device 6 designed in a way already described above in association with Figs. 5A-SC will, when actuated, hit the balance lever 20 of the inlet valve 2, whereby the inlet valve 2 is driven into its thoroughfare open state, and the refilling of the cistern 1 will occur within a very short period of time so that the toilet bowl can be flushed. However, the omitting of automatic refilling will warn the user or operator of the toilet that there is a sealing defect in the system which must be eliminated.

Fig. 7A depicts in a dotted line, a closing float 30 that can be used in preferred embodiments of the assembly as an additional component part of the float 3. Such a closing float 30 can be arranged above the float 3 of varying weight on the same suspending rod 38 which carries the float 3. The closing float 30 has a density lower than that of the water, and so in the course of the water level WL rising, and the cloasing float 30 immersing in the water, it is subjected to a buoyant force acting in upward direction whereby the torque which drives the inlet valve 2 into its closed position is substantially increased which contributes to an improved reliability of valve closing. In addition to this, by using a separate closing float 30, it is sufficient to design only the closing float 30 so as to be capable of possible height adjustment in order to determine the desired water level WL of the cistern 1, while the lower float 3 (which can be of a varying weight as applicable) controlling the opening of the valve can be rigidly fixed to the rod 38 without providing for its height adjustment. Using the above approach duly facilitates the adjustment of the desired water level WL in the cistern 1.

Figs. 8A-8F of the attached drawing show in combination with an additional closing float 30 of adjustable height on the rod 38, an opening float 31 of a design similar to that of the float 3 shown in Figs. 7A-7D. The closing float 31 has a density lower than that of the water. The hollow opening float 31 is arranged in a fixed way on <BR> <BR> <BR> the rod 38, it has bottom perforations 32, and at least one perforation 32 is provided at its top part at the highest point of its spherical body. When in operation, when the water level WL rises (Fig. 8B), the water flowing into the opening float 31 through the bottom perforations 32 totally fills in the inner space of the opening float 31 once the float is fully immersed into water (Fig. 8C). With the water level WL reaching its desired, prescribed level (Fig. 8D), a torque sufficient for driving the inlet valve 2 into its closed valve state is exerted by the light closing float 30 on the balance lever 20 of the inlet valve 2 of the assembly whereby the inlet valve is moved into its closed valve state in which no further water is supplied to the cistern 1 (Fig. 8E). After flushing, the <BR> <BR> <BR> automatic reopening of the inlet valve 2 is controlled by the opening float 31 of varying weight. Refilling of the cistern 1 only occurs if the water level WL of the cistern 1 rapidly drops as required for intensive emptying, i. e. flushing, because during the short period of time while the water escapes from the cistern 1, most of the water contained therein previously will still remain in the opening float 31 (Fig. 8F). The torque exerted on the balance lever 20 of the inlet valve 2 by the increased weight of the opening float 31 still containing a sufficient volume of water will be sufficient for actuating the toggle switch mechanism 4 of the inlet valve 2 and thus, the inlet valve 2 will be opened for automatic refilling. In the case of a slow water level drop in the cistern 1 as a result of a sealing failure, the cistern 1 will not be automatically refilled because for this mode of operation of the embodiment of the assembly comprising a combined float as shown in Figs. 8A to 8F, the operation is identical with what has already been described with reference to Figs. 7A-7D further above.

As a further preferred example, the design and certain characteristic phases of the operation of another combined float of varying weight is depicted in Figs. 9A-9F of the attached drawing. In this embodiment, the opening float 31 of the combined float is designed and shaped as an open top vessel, with a bottom part 34 featuring perforations 32. The opening float 31 of lower arrangement comprises a closing disc 36 which is vertically moveable relative to the rod 38, and the closing disc 36 functions as a choke or closing check valve that can close the perforations 32 in the outlet direction both ways, in a sealed manner and partially whereby a flow choke is effected. The upper closing float 30 of the combined float has a shape of a body of rotation. It is of lower density than that of the water, and it can be adjusted in height along the rod 38. Fig. 9A depicts the combined float when it is"in the dry"prior to the first filling up of the cistern 1. Fig.

9B shows the initial phase of filling up the cistern 1, when the water level WL rises, so does the closing disc 36, and through the perforations 32 of the bottom part 34, water flows into the opening float 31 as well. In the state depicted in Fig. 9C, the water level WL of the cistern 1 has reached the height of the closing float 30, the buoyant force acting on it drives the inlet valve 2 into its closed valve state, and the rising of the water level of the cistern 1 is stopped. Fig. 9D shows the closing disc 36 resting on the bottom part 34 of the opening float 31, closing thereby, at least partially, the perforations 32 in the bottom part 34. In the flushing phase of operation shown in Fig. 9E, the water level WL of the cistern 1 drops rapidly, whereby water is retained in the opening float 31, the weight of which after a further reduction of the water level WL (Fig. 9F) is sufficient to open the inlet valve 2 and the repeated automatic filling of the cistern 1 is started. If no closing disc 36 is used in the opening float 31 or a closing disc 36 not providing a sealed closing of the perforations 32 of the bottom part 34 is applied, the embodiment of the combined float shown in Figs. 9A-9F becomes in function closely similar to those shown in and described with reference to Figs. 7A-7D and 8A-8F above. With the changes mentioned above, due to the simultaneous emptying and loss of weight the opening float 31 will become unable to re-open the inlet valve 2 when a slow decrease of the water level WL of the cistern 1 occurs, and so the re-filling of cisterns 1 of assemblies with a sealing failure will not performed automatically. Instead of the closing disc 36, the perforations 32 may also be influenced by choking or closing elements of any other known design, for example by plugs or ball type check valves. It is important to note that due to the necessary transfer of the buoyant force to the balance lever 20 of the inlet valve 2 for closing, any connecting linkage between the closing float 30 and the balance lever 20 must be suitable for transferring forces in both directions such as the rod 38, while the opening float 31 may be connected by to the balance lever 20 directly or indirectly, by using a flexible suspension member only.

It is shown in Fig. 10 that in a combined float arrangement, the closing float 30 of a density lower than that of the water can also be designed as a bell shaped component part facing down and thus, open at the bottom. Also in such embodiments the closing float is arranged on the rod 38 in an adjustable height position relative to the rod 38.

When in operation with the water level WL rising gradually in the cistern 1, air is retained in the bell shaped closing float 30, and so a buoyant force of sufficient extent will be generated to act on the balance lever 20 of the inlet valve 2 for moving the latter into its closed position.

Because of mechanical loads arising during operation, noise effects resulting from fast flowing water as well as of aspects of lifetime and durability it has proved to be useful and necessary to find efficient means and measures for influencing and thus, improving the dynamic characteristics of the operation of the cistern assembly of the invention. It has been found e. g. that by applying at least one braking member to and/or by an appropriate selection of the shape of the float 3, the dynamic characteristics can be influenced very efficiently. For such reasons and for example only, in Fig. 11 a float 3 consisting of vertically spaced horizontal segments 37 is shown. Other different multi- disc designs of floats have proved to be advantageous as well.

Hygienic specifications render it necessary to ensure that in the case of a pressure drop in the water mains which may occur and cause a temporary vacuum in the delivery line of water, the water stored in the cistern 1 is prevented from flowing back into the delivery mains through the open inlet valve 2. Figs. 12A-12C of the attached drawing show an arrangement whereby the above requirement can fully be met. Herein, a filling pipe 25 is connected to the outlet chamber 22 of the inlet valve 2 of the cistern assembly of the invention. A check valve 7 duly preventing the flow of water to the inlet valve 2 from the cistern 1 is arranged the filling pipe 25. With the check valve 7 design shown by way of example in Figs 12A-12C, the upper entrance end of the filling pipe 25 has a narrowed entrance aperture forming a valve seat 26. The filling pipe 25 comprises an open bottom bell shaped valve member 70 which is lighter than the water and is arranged in a vertically moveable way within the filling pipe 25. The valve member 70 comprises a rubber seal 71 located at its upper end. The outer diameter of the valve member 70 is smaller than the inner diameter of the filling pipe 25, and at its bottom end position, the valve member 70 is held by a limiter 74. Fig. 12A depicts the phase of operation when the inlet valve 2 opens, and the mains water pressure also opens the check valve 7. Fig.

12B depicts the arrangement showing its state during the filling of cistern 1, when the water is allowed to unobstructed flow into the cistern 1 through the open check valve 7, via a channel 72 of annular cylindric shape between the external mantle of the valve member 70 and the inner mantle of the filling pipe 25. In Fig. 12C, a dotted arrow depicts the operating condition when as a result of a pressure drop vacuum is present in the delivery mains line. In such a case, the valve member 70 which is lighter than the water is forced to rise and the rubber seal 71 is pressed in a sealed way, against the valve seat 26 of the filling pipe 25 by the suction effect of the vacuum. Thereby the check valve 7 is in its closed position and blocks the return flow of water from the cistern 1 to the mains. Fig. 13 shows another design of the check valve 7, wherein a check ball 73 made of a material lighter than water and co-acting with a valve seat 26 of the filling pipe 25 of similar design is used as a moving closure member in the valve. When in operation as shown in the Fig. 13 of the drawing, the water flowing in through the inlet valve 2 keeps the check ball 73 pressed against a grating or sieve type limiter 74 whereby the filling water is allowed to freely flowing into the cistern 1. If vacuum occurs in the delivery water mains, its suction effect draws the check ball 73 against the valve seat 26 of the filling pipe 25, whereby the check valve 7 closes and the return flow of water from the cistern 1 to the delivery mains is prevented with high reliability.

Finally, in Figs. 14A and 14B of the attached drawing another preferred design of the float controlled inlet valve 2 of the cistern assembly of the invention similar to that shown in Figs. 3A and 3B is shown in elevation. Here, a closing float 30 as component part of a combined float is arranged in a way adjustable in hight on a sleeve 28 that is slideably guided along the filling pipe 25 of the inlet valve 2. An opening float 31 having a conically shaped end portion at the top is also fixed to the sleeve 28. The sleeve 28 is connected to the end of the balance lever 20 of the inlet valve 2 via a coupling rod 29 having a forked end at the top. The closing float 30 and the opening float 31 are arranged in an open bottom external pipe surrounding coaxially, the filling pipe 25. The inner diameter of the external pipe is slightly larger than the external diameter of the opening float 31. In the external pipe, below the closing float 30 there is a fixed braking member 27 having an inner opening which is suitable for receiving the upper conical end of the opening float 31. In the open valve state of the inlet valve 2 (Fig. 14A), the water flowing in fills up the cistern 1 and the water level rises therein. The closing float 30 and the opening float 31 are rising simultaneously. When reaching the prescribed, desired water level, the closing float 30 causes the toggle switch mechanism 4 to move, the balance lever 20 is tilted to its upper end position and the closure member (not shown) of the inlet valve 2 is driven into its closing end position. This closing movement is attenuated, however, because during the simultaneous upwards movement of the opening float 31, the water volume contained in the external pipe in the space between the braking member 27 and the conical top end of the opening float 31 must be forced to leave the space (Fig. 14B). This causes a significant braking effect which becomes increasingly intensive by the fact that during the rising movement of the opening float 31, its upper conically shaped end portion gradually moves into the inner opening of the braking member 27, increasingly reducing thereby the free cross section of the opening through which the water is being forced out. With such a design, in addition to or instead of the above mentioned other means and measures such as the use of brake discs or at least one float consisting of segments etc., the dinamic characteristics of the inlet valve can also be enhanced very efficiently.

The inlet valve of the cistern assembly of the present invention allows for a high rate of water flow therethrough resulting in a rapid filling of the cistern. The flush assembly of the invention is especially suitable for serving high turnover public toilets.

Its quiet operation is a highly valued benefit when it is used, for example, in hotels or in residential houses. Certain embodiments of the inlet valve are able to fill up the cistern with a substantially controlled flow of water by self-regulating, at least between certain limits, the actual flow aperture through the valve, depending on the current mains pressure. Embodiments of the inlet valve capable of automatic opening and closing can also be arranged as replacement units into cisterns of already existing conventional toilet flush assemblies. The cistern assembly of the invention is less sensitive to contamination and limescale. The assembly requires little if no maintenance, closes rapidly and reliably, and is of substantially leakproof design. It can be operated in a spare flush mode using a limited volume of water only. Toilet flush assemblies preventing any unnecessary (excess) use of water by not refilling cisterns that have been emptied slowly due to leakage in the system can also be designed by making use of the invention. In toilet flush assemblies according to the present invention as compared to those of known assemblies, a cistern of substantially smaller size can be used, and as a result of this, the entire cistern assembly could be more compact and of enhanced aesthetic appearance.

List of Reference Signs used in the Drawings cistern 1 flush outlet 10 inlet valve 2 balance lever 20 pressure chamber 21 outlet chamber 22 flow passage 23 closure member 24 filling pipe 25 valve seat 26 braking member 27 sleeve 28 coupling rod 29 float 3 closing float 30 opening float 31 perforation 32 neck portion 33 bottom part 34 holder 35 closing disc 36 segment 37 rod 38 space portion 39 toggle switch mechanism 4 coupling link 40 spring member 41,42 flush valve 5 bell shaped member 50 flush device 6 double arm lever 60 arm 61,62 fulcrum 63 driving tongue 64 actuator 65,66 rocker 67 push button 68 spring 69 check valve 7 valve member 70 rubber seal 71 channel 72 check ball 73 limiter 74 water level WL stroke, H