Syphon assembly and actuator therefor

Abstract

A fill valve assembly (9, 109) for connection with a flushing syphon or other flushing valve. The assembly (9, 109) includes a float operated equilibrium valve (90, 190) and a branch element (92, 192) fluidly connected upstream the equilibrium valve (90, 190) and including an outlet (98) for providing fluid flow to one or more fluid pressure driven actuators (6).

Claims

1. A syphon assembly for discharging water from a cistern, the assembly comprising an inverted generally U shaped duct having an upleg and a downleg, an open-ended chamber fluidly connected to the upleg, a piston movable in the chamber, a hydraulically-driven actuator operatively connected to the piston and a piston rod with a first end connected to or formed integrally with the piston and a second end connected to or formed integrally with a prime mover of the actuator, wherein the actuator is operable, in use, to move or at least assist in the movement of the piston within the chamber to initiate a syphonic flushing action.

2. A syphon assembly as claimed in claim 1, wherein the actuator is a hydraulic actuator fluidly connected or connectable, in use, to a mains water supply.

3. A syphon assembly as claimed claim 1, wherein the actuator comprises an actuator cylinder and the prime mover comprises an actuator piston reciprocable within the actuator cylinder.

4. A syphon assembly as claimed in claim 3, wherein the actuator cylinder comprises an inlet at or adjacent a first of its ends and a vent or vents at or adjacent at a second of its ends.

5. A syphon assembly according to claim 3, wherein the actuator piston is sized and/or dimensioned such that a fluid flow entering the cylinder from the inlet forces the piston from the first end toward the second end and such that fluid is able to flow between the piston head and the cylinder.

6. A syphon assembly according to claim 1 further comprising a control valve mechanism connected to the actuator for controlling the actuator.

7. A syphon assembly according to claim 6 further comprising a control lever or button or proximity sensor or switch for operating the control valve mechanism.

8. A syphon assembly according to claim 6, wherein the control valve mechanism comprises an operating valve and a pilot valve.

9. A syphon according to claim 8, wherein the operating valve is mounted to, or remote from, the chamber.

10. A syphon assembly according to claim 8, wherein the operating valve comprises an equilibrium valve and the pilot valve comprises a bleed valve.

11. A syphon assembly according to claim 6 further comprising a fill valve assembly including a branch element fluidly connected to the control valve mechanism for supplying mains water thereto.

12. A syphon assembly according to claim 1 further comprising a dual flush mechanism for enabling a user to selectively operate the assembly to flush all or only some of the contents of a cistern to which the syphon assembly is connected in use, wherein the assembly comprises a passage extending from the interior of the chamber to the interior of a cistern in use at a position that is higher than the open end of the chamber and a seal biased to a closed position in which the passage is closed, wherein the assembly is configured such that the seal is moved from the closed position or condition to an open position or condition only when the piston is at or adjacent a fully raised or uppermost position such that a maximum volume flush can be effected by raising the piston and allowing it to drop to an intermediate position below its fully raised or uppermost position without delay, but a lesser volume flush can only be effected by holding the piston in a substantially fully raised or uppermost position until the water level drops below the passage opening allowing air to enter the chamber and interrupting the syphonic action.

13. A kit of parts for assembly into an assembly according to any one of claim 1, the kit comprising an inverted generally U shaped duct having an upleg and a downleg, an open-ended chamber fluidly connected or connectable to the upleg, a piston for movable receipt within the chamber, a hydraulically-driven actuator operatively connected to the piston and a piston rod with a first end connectable to or formed integrally with the piston and a second end connectable to or formed internally with a prime mover of the actuator.

14. A cistern comprising an assembly according to claim 1.

15. A toilet comprising a cistern according to claim 14.

16. A syphon assembly for discharging water from a cistern, the assembly comprising an inverted generally U shaped duct having an upleg and a downleg, an open-ended chamber fluidly connected to the upleg, a piston movable in the chamber, a hydraulically-driven actuator operatively connected to the piston and a dual flush mechanism for enabling a user to selectively operate the assembly to flush all or only some of the contents of a cistern to which the syphon assembly is connected in use, wherein the actuator is operable, in use, to move or at least assist in the movement of the piston within the chamber to initiate a syphonic flushing action, the assembly comprising a passage extending from the interior of the chamber to the interior of a cistern in use at a position that is higher than the open end of the chamber and a seal biased to a closed position in which the passage is closed, the assembly being configured such that the seal is moved from the closed position or condition to an open position or condition only when the piston is at or adjacent a fully raised or uppermost position such that a maximum volume flush can be effected by raising the piston and allowing it to drop to an intermediate position below its fully raised or uppermost position without delay, but a lesser volume flush can only be effected by holding the piston in a substantially fully raised or uppermost position until the water level drops below the passage opening allowing air to enter the chamber and interrupting the syphonic action.

Description

(1) Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings in which:

(2) FIG. 1 is a partially segmented perspective view of a syphon assembly according a first embodiment to the present invention;

(3) FIG. 2 is a cross sectional side view of the syphon assembly of FIG. 1;

(4) FIG. 3 is a perspective view of the flush activator for use with the syphon assembly of FIGS. 1 and 2:

(5) FIG. 4 is an exploded view of the flush activator of FIG. 3;

(6) FIG. 5 is a cross-sectional view of the flush activator of FIGS. 3 and 4 shown in an unactuated condition;

(7) FIG. 6 is a view similar to that of FIG. 5 with the flush activator shown in an actuated condition;

(8) FIG. 7 is a perspective view of a bottom entry fill valve assembly incorporating a branch element for use with the syphon assembly of FIGS. 1 and 2;

(9) FIG. 8 is a perspective view of the fill valve assembly of FIG. 7 sectioned through the fill valve and branch element;

(10) FIG. 9 is a partially exploded view of the fill valve assembly of FIGS. 7 and 8;

(11) FIG. 10 is a perspective view of a side entry fill valve assembly with a branch element in a first orientation for use with the syphon assembly of FIGS. 1 and 2;

(12) FIG. 11 is a perspective view of the fill valve assembly of FIG. 10 with the branch element in a second orientation;

(13) FIG. 12 is a perspective view of the fill valve assembly of FIG. 10 sectioned through the fill valve and branch element;

(14) FIG. 13 is a partially exploded view of the fill valve assembly of FIG. 10;

(15) FIG. 14 is a partially segmented perspective view of syphon assembly according a second embodiment;

(16) FIG. 15 is a section view of the actuation system of the syphon assembly of FIG. 14 illustrating the flush activator operatively connected to the equilibrium valve and showing the flow of mains water into the equilibrium valve;

(17) FIG. 16 is a partial perspective view of the partial flush closure element of the syphon assembly of FIG. 14 shown in an open position:

(18) FIG. 17 is a view similar to that of FIG. 16 but showing the partial flush closure element in a closed position; and

(19) FIGS. 18, 19 and 20 are partial perspective views of the adaptable flush volume feature of the syphon assembly of FIG. 14 shown with the closure element installed partially removed and fully removed positions respectively.

(20) Referring to FIGS. 1 and 2 there is shown a syphon assembly 1 for discharging water from a cistern (not shown). In this embodiment, the syphon assembly 1 includes an adjustment means 10 for adjusting the configuration of the syphon. The syphon assembly 1 includes an inverted generally U shaped duct 11 fluidly and telescopically connected to an upleg 2 and a downleg 3, an enlarged rectangular chamber 4 integral with the upleg 2 and having an open lower end 40, a piston 5 movable in the chamber 4 and a hydraulic actuator 6 connected to the piston 5 by a piston rod 7 that extends through a hole 41 in an upper wall of the chamber 4. The downleg 3 is connected, in use, to the flush pipe of a cistern (not shown) to feed flush water into a toilet pan (not shown). The hydraulic actuator 6 is operable to move the piston 5 within the chamber 4 to initiate a syphonic flushing action in use.

(21) The adjustment means 10 is provided by a releasable fastener 12 that secures the U shaped duct 11, the upleg 2 and the downleg 3 together by engaging simultaneously a respective chain of lugs 13 in the manner described in GB2486776.

(22) In this embodiment, the chamber 4 includes an adaptable flush volume feature 42 similar to the arrangement disclosed in GB2338723. More specifically, one of the wider, side walls of the chamber 4 is provided with a vertically extending venting aperture in the form of a generally rectangular slot 43 closed at its upper end, open at its lower end and having a raised bridging portion 44 across the lower end. The slot 43 also includes an edge profile that slidably receives and releasably and sealingly engages a correspondingly shaped closure element 45. The closure element 45 includes two removable plugs 46 for varying the flush volume, a lower flange 47 and a pair of locking lugs 48. The closure element 45 is inserted into and/or removed from the slot 43 through the open lower end and is secured in place by captivating the bridging portion 44 of the chamber 4 between the flange 47 and locking lugs 48.

(23) The piston 5 includes a plate 50 with a coextensive diaphragm 51 and a weight 52 each of which is secured at its centre to the centre of the upper major surface of the plate 50. The plate 50 is formed of a rigid or semi-rigid plastics material in this embodiment and incorporates a plurality of apertures 52 through its thickness and a central engaging hole 53 with a counterbore on the opposite side of the piston 5 to the diaphragm 51 and weight 52. The diaphragm 51 is formed of a sheet of flexible plastics material in this embodiment such that a flow of water from beneath the piston 5 through the apertures 52 causes the diaphragm 51 to raise and allow water to flow, but prevents flow in the opposite direction, thereby operating as a one-way valve.

(24) The actuator 6 includes an actuator piston 60 reciprocable within an actuator cylinder 61. The actuator piston 60 includes a threaded hole 62 for securement with an upper end of the piston rod 7 and the piston rod 7 extends through a first end of the actuator cylinder 61. The actuator cylinder 61 includes a radial inlet 63 adjacent its first end and four peripheral vents or slots 64 adjacent a second end thereof. The actuator cylinder 61 also includes an anti-splash cap 65, which covers the second end and surrounds the peripheral vents or slots 64, but is spaced therefrom to provide a gap for water and/or air to pass. The inlet 63 is connected to an equilibrium valve (not shown) by a flexible hose 66.

(25) In this embodiment, the actuator piston 60 is sized and dimensioned such that a fluid flow entering the actuator cylinder 61 from the inlet 63 forces the actuator piston 60 from the first end of the actuator cylinder 61 toward the second end thereof. The actuator piston 60 is also sized and dimensioned such that the clearance between the actuator piston 60 and the cylinder 61 permits some fluid to flow therebetween. In this embodiment, the piston 60 is formed of a plastics material having a relatively low weight.

(26) The piston rod 7 is substantially cylindrical in shape with an undersized first portion 70, which is an upper portion in this embodiment, and a second portion 71, which is a lower portion in this embodiment. In this embodiment, the first portion 70 is sized and dimensioned to provide clearance between the hole 41 in the chamber 4 to allow air to pass therebetween, while the second portion 71 is sized and dimensioned to prevent the passage of air when received within the hole 41. The piston rod 7 also includes a threaded end 72 at the end of the first portion 70 and an engaging head 73 at the end of the second portion 71. The threaded end 72 is received within and engages the threaded hole 62 of the actuator piston 60 to secure the piston rod 7 to the actuator piston 60. The engaging head 73 is an enlarged portion that is received within the correspondingly shaped engaging hole 53 of the piston plate 50.

(27) The supply of mains water is controlled by a control assembly that includes the equilibrium valve (not shown), which is fluidly connected to a flush activator 8 that incorporates a bleed valve 80 operated by an integral a pushbutton 81 (shown in FIGS. 3 to 5). The bleed valve 80 includes an inlet housing 82, an outlet housing 83 and a valve member 84. The flush activator 8 also includes a push fit fitting 85 for securely receiving a tube 85a, a compression spring 87 and a circular mounting flange 86 with an internally threaded hollow body 86a with a hexagonal circumference 86b.

(28) The pushbutton 81 includes a body 81a with an internally threaded blind hole 81b extending from a first end thereof and an enlarged head 81c at a second end thereof. The head 81c includes a convex actuation surface 81d on a first side thereof and an annular recess 81e on a second side thereof.

(29) The inlet housing 82 is hollow and substantially cylindrical with a longitudinal bore that narrows at its centre to provide an inlet port 82a. The push fit fitting 85 is securedly received within a first end 82b of the inlet housing 82 by an interference fit with an O-ring seal 85b captivated between the push fit fitting 85 and an adjacent internal surface of the inlet housing 82. The inlet housing 82 also includes an internally threaded second end 82c.

(30) The outlet housing 83 is also hollow and substantially cylindrical with four radial outlets 83a fluidly connected to and extending from a longitudinal bore 83a, which receives and guides the valve member 84. The outlet housing 83 includes an undersized, externally threaded first end 83b for threaded engagement with the second end 82c of the inlet housing 82 and an O-ring seal 83c received within a circumferential groove to provide a sealing engagement therebetween. The outlet housing 83 also includes a flange 83d at a second end thereof and an external thread 83e between the outlets 83a and the flange 83d for engagement with the mounting flange 86 in order to captivate a wall portion (not shown) of a cistern (not shown) or water closet furniture (not shown) therebetween in the normal way.

(31) The valve member 84 includes a first, tapered end 84a, a snap ring 84b received within a first circumferential groove 84c adjacent the first end 84a, a first O-ring seal 84d received within a second circumferential groove 84e, a second O-ring seal 84f received within a third circumferential groove 84g and a second, externally threaded end 84h for engagement with the blind hole 81d of the pushbutton 81. The valve member 84 also includes a circumferential undercut 84i between the O-ring seals 84d, 84f.

(32) As shown more clearly in FIG. 5, the compression spring 87 is located around the valve member 84 and pushbutton body 81a with one of its ends received within the annular 81e of the pushbutton 81. The compression spring 87 is captivated between the pushbutton head 81c and an internal annular recess 83f of the outlet housing 83 and biases the valve member 84 toward a closed position in which the snap ring 84b abuts the first end 83b of the outlet housing 83. With the valve member 84 in the closed position, the first O-ring seal 84d seals against the bore 83a of the outlet housing 83 to close fluid communication between the inlet port 82a and the outlets 83a.

(33) Depression of the pushbutton 81 moves the valve member 84 from the position illustrated in FIG. 5 to that shown in FIG. 6, which moves the O-ring seal 84d out of engagement with the bore 83a, thereby allowing pressurised water from the bleed port of the equilibrium valve (not shown) to exit through the outlets 83a via the undercut 84i. This releases pressure from a pressure chamber of the equilibrium valve (not shown), thereby opening the equilibrium valve (not shown).

(34) The equilibrium valve (now shown) in this embodiment mounted remotely from the syphon assembly 1 and is fluidly connected to a domestic mains water system (not shown) via a fill valve assembly 9, 109 to selectively provide a flow of water at mains pressure to the actuator cylinder 61 through the inlet 63. The use of a bottom entry fill valve assembly 9 or a side entry fill valve assembly 109 depends upon the cistern (not shown) into which the syphon assembly 1 is incorporated in use.

(35) As shown in 7 to 9, the bottom entry fill valve assembly 9 includes a float controlled diaphragm valve 90 of the kind described in GB2332731, the contents of which are incorporated herein by reference, in which water pressure on opposite sides of the diaphragm is kept substantially in equilibrium so that when a lever mounted float 91 drops, a bleed aperture is exposed and unseats the diaphragm by a small change in pressure differential. The fill valve assembly 9 according to this embodiment differs from the aforementioned design in that there is provided a branch element 92 that cooperates with the valve 90 to feed the actuator 6 of the syphon assembly 1. Specifically, the filter chamber 90a that houses the conical inlet filter 90b of the valve 90, which is fed by the vertical feed pipe 90c, includes a pair of side openings 90d, 90e in addition to the upper outlet 90f extending horizontally from the filter chamber 90a, wherein the branch element 92 is receivable in either one of the openings 90d, 90e and secured to the valve 90 by a clamp element 93.

(36) The branch element 92 in this embodiment includes a twin barrel housing 94 with an open end 94a, a first side that includes an undersized inlet spigot 95 opposite the open end 94a and feeding into an inlet chamber 96 and a second side that includes a filter chamber 97 feeding into a radial outlet 98 extending perpendicularly from the filter chamber 97. The inlet spigot 95 includes an inlet passage 95a that feeds into a the inlet chamber 96, which is open at the open end 94a of the housing 94. The filter chamber 97 is also open at the open end 94a of the housing 94. The branch element further includes a closure element 99 for closing the open end 94a of the housing 94, which has a facing internal surface shaped to provide fluid communication between the open ends of the inlet chamber 96 and the filter chamber 97.

(37) The inlet spigot 95 includes an outer circumferential groove 95b that receives an O-ring seal 95c and an external circumferential securing flange 95d. The inlet chamber 96 receives pair of non-return valves 96a, 96b to prevent backflow and having respective O-ring seals, the non-return valves 96a, 96b being separated by a spacer 96c received and captivated therebetween to enable independent operation.

(38) The filter chamber 97 extends parallel with respect to the inlet chamber 96 and is also open at the same end of the housing 94, but it includes a hemispherical base 97a and feeds into the outlet 98 radially. The filter chamber 97 houses a conical inlet filter 97b.

(39) The outlet 98 is hollow and substantially cylindrical in shape with two steps, providing three internal diameters, wherein a push fit fitting 98a is received within the largest diameter, free end of the outlet portion 98 and abuts one of the steps, while an O-ring seal 98b is received within the intermediate diameter and abuts a second of the steps for sealing with a tube 98c that is received within the smallest diameter and feeds the inlet of the equilibrium valve (not shown).

(40) The closure element 99 includes a pair of inwardly extending flanges 99a that cooperate with a pair of opposed external flanges 94b projecting outwardly from the open end 94a of the housing 94 to secure the closure element 99 to the housing 94 and to seal the open end 94a thereof. The closure element 99 also includes an O-ring seal 99b received within a circumferential groove of a spigot portion 99c thereof, which O-ring seal 99b sealingly cooperates with an internal surface of the second end of the housing 94.

(41) The clamp element 93 is shaped to match the contours of the portion of the valve 90 that houses the valve filter chamber 90a, but also includes inwardly extending radial flanges 93a adjacent the openings 90d, 90e for cooperation with the securing flange 95d of the inlet spigot 95. Each radial flange 93a extends inwardly from a respective hollow, part cylindrical portion 93b of the clamp element 93, circumscribes more than 180 to provide a C-shaped receptacle and includes a lead-in to facilitate insertion. In use, one of the C-shaped receptacles receives by a snap fit the portion of the inlet spigot 95 between the securing flange 95d and the outer surface of the inlet chamber 96 of the housing 94 such that the flange 93a is captivated therebetween.

(42) The branch element 92 in this embodiment is reversible in that it may be inserted into either of the valve openings 90d, 90e depending upon the space constraints within the cistern (not shown). The fill valve assembly 9 also includes a plug 93c for closing off the unused opening 90d, 90e, which cooperates with the other of the C-shaped receptacles of the clamp element 93. The plug 93c includes similar features to the spigot portion 95, namely an outer circumferential groove 93d that receives an O-ring seal 93e, an external circumferential securing flange 93f and an oversized head 93g between which flange 93f and head 93g is received the other flange 93a of the clamp element 93 to seal off the other of the valve openings 90d, 90e.

(43) Turning now to FIGS. 10 to 13, the side entry fill valve assembly 109 is similar to the bottom entry fill valve assembly 9, wherein like references depict like features that will not be described further. The side entry fill valve assembly 109 differs from the bottom entry fill valve assembly 9 in that the vertical feed pipe 90c is replaced with a threaded extension 190c of the filter chamber housing 190a, the side openings 190d, 190e thereof are recessed within the valve 190 and are in fluid communication with one another via an annular recess 190f and the inlet spigot 95 is replaced with an annular inlet member 195 of the branch element 192. The valve 190 also includes a pair of O-rings 190g each received within a respective groove 190h on either side of the annular recess 190f.

(44) The annular inlet member 195 includes a cylindrical body 195a with a radial passageway 195b that feeds into the inlet chamber 96 and a square flange 195c with a square shaped recess 195d for receiving a correspondingly shaped locating flange 190f of the valve 190. The side entry fill valve assembly 109 also includes a pair of locking nuts 193a, 193b for securing the annular inlet member 195 to the valve 190 such that it is aligned with the side openings 190d, 190e. The branch element 192 in this embodiment is also reversible by rotating it through 180 degrees prior to locating the flange 190f of the valve 190a into the recess 195d of the branch element 195 and securing them together with the locking nuts 193a, 193b.

(45) In use, when a user depresses the pushbutton 81, the equilibrium valve (not shown) opens, fluid flows into the cylinder 61 through the inlet 63, driving the actuator piston 60 upward, pulling the piston rod 7 to drive the piston 5 upward within the chamber 4 to initiate a syphonic flushing action. In this embodiment, a full flush may be initiated by pressing and holding the push button 81 so that the equilibrium valve (not shown) stays open, thereby ensuring that the second, lower portion 71 of the piston rod 7 closes the hole 41 in the chamber 4. The flushing action continues until the water level reaches the base of the chamber 4, at which point the syphonic effect is broken and the cistern (not shown) refills in the known manner by the float operated fill valve 9, 109. A partial flush may be initiated by pressing and releasing the push button 81 so that the equilibrium valve (not shown) closes after the flush is initiated, with the weight 52 forcing the piston 5 downward such that the first portion 70 of the piston rod 50 fits loosely within the hole 41 of the chamber 4, thereby providing a vertical passage therebetween to break the siphonic action when the water level drops below the hole 41.

(46) Clearly, the reverse of the partial flush arrangement described above is also envisaged. This may be achieved, for example, by configuring the syphon assembly 1 as described in GB2329398, the entire contents of which are incorporated herein by reference.

(47) Turning now to FIG. 14, there is shown a syphon assembly 100 according to a second embodiment, which is similar to the syphon assembly 1 according to the first embodiment, wherein like references depict like features that will not be described further. The syphon assembly 100 according to this embodiment differs from that of the first embodiment in that the equilibrium valve 101 is mounted directly to the hydraulic actuator 6, the means by which a partial flush is achieved has been reconfigured, the weight 52 is incorporated within the actuator piston 160 and piston rod 107 and the adaptable flush volume feature 142 has been reconfigured for improved access and strength.

(48) The equilibrium valve 101 in this embodiment functions in a manner that is similar in principle to the diaphragm valves 90, 190 of the fill valve assemblies 9, 109 described above. Specifically, the equilibrium valve 101 includes a diaphragm 110 with a peripheral flange 111 captivated between opposed housing portions 112a, 112b, a central valve portion 113 with a central hole incorporating a flow regulation pin 114 and a flexible bridging portion 115 joining the peripheral flange 111 to the valve portion 113. As shown in FIGS. 14 and 15, the downstream side of the diaphragm 110 has a larger surface area exposed to fluid pressure than the upstream side thereof. The upstream housing portion 112a includes a valve seat 112c and a plurality of radial outlets 112d fluidly connected to the inlet 63 of the actuator 6. The downstream housing portion 112b includes a central outlet 112e that feeds the tube 85a connected to the flush activator 8 at one end and to a push fit fitting 112f mounted to the actuator 6 at the other end. The mains water inlet tube 98c is connected to the equilibrium valve 101 by a push fit fitting 116.

(49) In use and with the activator 8 in the position shown in FIGS. 5 and 15, water pressure on opposite sides of the diaphragm 110 is kept substantially in equilibrium, which causes the valve portion 113 of the diaphragm 110 to be biased against the valve seat 112c on the upstream housing portion 112a. When the pushbutton 81 of the activator 8 is depressed, the passage between the outlet 112e of the downstream housing portion 112b and the radial outlets 83a of the activator 8 is open, which reduces the pressure on the downstream side of the diaphragm 110, owing to the restricted flow of pressurised water passed the flow regulation pin 114. This in turn, unseats the diaphragm 110 and opens fluid flow between the mains water inlet tube 98c and the radial outlets 112d of the equilibrium valve 101 and drives the piston 160 to raise the piston rod 107 in order to initiate the flush.

(50) The piston rod 107 in this embodiment has a constant diameter and is received within a spigot 152 connected to the syphon piston 5. An interrupted annular vent 141 surrounds the hole 41 in this embodiment, which vent 141 provides a vertical passageway joining the interior of the chamber 104 of the syphon assembly 100 to the inside of the cistern (not shown). The syphon assembly 100 includes a sealing element 171 in the form of a washer 172 with a hollow, cylindrical portion 173 depending therefrom and compression spring 174 all surrounding the piston rod 107. The washer 172 and spring 174 are captivated between the base of the actuator cylinder 61 and the top of the vent 141 such that the spring 174 urges the washer 172 against the top of the chamber 104 to seal the vent 141.

(51) In use, when the piston rod 107 is raised to its uppermost position, the spigot 152 urges the cylindrical portion 173, raising sealing washer 172 against the bias of the spring 174, thereby exposing the vent 141. If the pushbutton 81 is held in a depressed position as shown in FIG. 6, the flush continues until the water level reaches the vent 141, at which point the syphonic action is interrupted to provide a partial flush. If the pushbutton 81 is depressed and released, the syphon piston 5 drops as the water in the actuator cylinder 61 flows around the piston 160 and the sealing washer 172 is urged against the vent 141 under the influence of the biasing spring 174. The use of a compression spring 174 is particularly advantageous because it ensures that the vent 141 is sealed before the water level drops to the level of the vent 141, which could inadvertently result in a partial flush where a full flush is requested. In this embodiment, the piston 160 and rod 107 are both formed of a heavier material than that of the first embodiment, for example a brass material, in order to obviate the need for a separate weight 52 as in the syphon assembly 1 according to the first embodiment.

(52) The adaptable flush volume feature 142 in this embodiment is incorporated with the outer, short side 140 of the chamber 104, as shown more clearly in FIGS. 19 and 20. In this embodiment, chamber 104 includes a plurality of horizontal reinforcing ribs 141 spaced vertically along its height. The chamber 104 includes an elongate opening 143 extending vertically with an open bottom and a closed top similar to the slot 43 of the syphon 1 of the first embodiment. However, engagement between the opening 143 and the closure element 145 in this embodiment is provided by respective cutouts 141a in each reinforcing rib 141 extending through its thickness on the side thereof adjacent the opening 143, thereby providing an interrupted vertical slot that is open at its upper end.

(53) Each cutout 141a is substantially rectangular with an enlarged central portion to permit the removable plugs 146 of the closure element to pass therethrough. In this embodiment, there is provision for up to five removable plugs 146 only four of which are shown. The closure element 145 includes an upper flange 147 with a curved recess 147a, wherein the outer portions of the flange 147 abut the region of the uppermost reinforcing rib 141 surrounding the cutout 141a when the closure element 145 is received therein in order to hold it in place. Thus, the closure element 145 can be removed from above by simply placing a finger within the recess 147a and lifting the closure element 145, which is particularly advantageous as this can be done with the syphon 100 located in situ within the cistern (not shown).

(54) It will be appreciated by those skilled in the art that several variations are envisaged without departing from the scope of the invention. For example, the hydraulic actuator 6 may be replaced with a pneumatic, electromagnetic or any other power-driven actuator. Accordingly, the source of power that drives the actuator may be provided by any other suitable means. Furthermore, the weight 52 may be replaced by any suitable biasing means, such as a spring or other such arrangement. The partial flush means need not be provided by an undersized portion of the piston rod 7 or even a vertical passage as described. Any other partial flush means may be provided. The syphon assembly 1 need not include an adjustment means 10 or may incorporate some other adjustment means.

(55) It will be appreciated by those skilled in the art that any number of combinations of the aforementioned features and/or those shown in the appended drawings provide clear advantages over the prior art and are therefore within the scope of the invention described herein.