GB2536308A - Syphon - Google Patents

Abstract

A syphon assembly (1 fig 1) for discharging water from a cistern. The assembly includes an inverted, generally U shaped duct (2 fig 1), an open-ended chamber (3 fig 1) and a piston (4 fig 1) movable in the chamber to which a flexible diaphragm 50, 51 is mounted for initiating a syphonic action. The duct includes an upleg (20 fig 1) and a downleg (21 fig 1) and the chamber is fluidly connected to the upleg. The assembly includes a constraining means 52, 53, 54, (35 fig 2) that is configured to constrain at least a peripheral portion of the diaphragm such that it deforms in a substantially predetermined manner. A further embodiment relates to a syphon assembly comprising a diaphragm with a hinged portion. A further embodiment relates to a syphon assembly wherein a valve means comprises two pivotable flaps. A further embodiment relates to a syphon assembly comprising a diaphragm that abuts against a buttress means. A further embodiment relates to a syphon piston comprising a cross member and a plurality of beams extending between the cross member and a peripheral portion of the piston.

Description

SYPHON

This invention relates generally to a syphon and more particularly to a syphon for selectively discharging water from a cistern into a toilet pan. More specifically, although not exclusively, this invention relates to syphon assemblies, components for such assemblies and to cisterns and toilets incorporating such assemblies.

Typical cistern draining syphons include an inverted generally U shaped duct having an upleg and a downleg, the upleg being provided with an enlarged chamber having a lower end open to the interior of the cistern in use. The downleg generally forms or is connected to an outlet of the cistern for delivery of flushing water to an associated toilet pan or the like.

Within the chamber is located a vertically displaceable piston in the form of a flat plate with openings through its thickness and a flexible diaphragm of, for example, rubber or plastics material, secured at its centre. The piston is movable in the chamber to initiate a syphonic flushing action and the diaphragm acts as a one way valve that opens once the syphonic action starts, thereby discharging water from the cistern in operation.

Draining syphons of this kind are generally operated by a lever whose end is connected to a piston rod attached to the piston such that actuation of the lever raises the piston, thereby raising the level of water within the syphon over the bight of the U and priming the syphon to initiate the syphonic action.

The applicants have observed that the configuration of the piston and diaphragm can occasionally impede effective initiation of a syphonic action, requiring additional attempts and causing water wastage and/or inconvenience to users. Wearing of the diaphragm is also a well-known issue, which necessitates its replacement periodically.

It is a non-exclusive object of the invention to provide a syphon that overcomes or at least mitigates one or more issues associated with known systems. It is a more general non-exclusive object of the invention to provide an improved syphon, for example one requiring less maintenance.

Accordingly, a first aspect of the invention provides 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 and a piston movable in the chamber to which a flexible diaphragm is mounted for initiating a syphonic action, wherein the assembly comprises a constraining means configured to at least partially constrain a peripheral portion of the diaphragm such that it deforms in a substantially predetermined manner on initiation of a syphonic action.

By constraining a peripheral portion of the diaphragm such that it deforms in a predetermined manner, the restriction of water flow through the piston to the upleg and the wear on the diaphragm can both be reduced, thereby improving the efficiency of the syphon and prolonging the life of the diaphragm.

At least part of the constraining means may comprise or be provided by the diaphragm being secured at one or more, e.g. opposed, peripheral portions of the piston, for example to provide a hinge thereacross about which at least part of the diaphragm is configured to pivot, in use, on initiation of syphonic action.

Another aspect of the invention provides 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 and piston movable in the chamber to which a flexible diaphragm is mounted for initiating a syphonic action, wherein the diaphragm is secured at opposed peripheral portions of the piston to provide a hinge thereacross about which at least part of the diaphragm is configured to pivot, in use, on initiation of syphonic action, e.g. to allow water to flow through the piston.

At least one or each of the peripheral portions may comprise an outer edge, or a portion substantially at or adjacent an outer edge, of the piston. Additionally or alternatively, the portion of the diaphragm that is secured to the peripheral portion may comprise an outer or peripheral portion thereof, e.g. a portion substantially at or adjacent an outer edge thereof.

Yet another aspect of the invention provides 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 and a piston movable in the chamber and including a valve means, wherein the valve means comprises two flaps configured to pivot, in use, in the same or substantially the same direction on initiation of syphonic action, e.g. to a position in which each flap at least partially diverts a flow of water through the piston and/or toward the upleg.

The provision of two flaps that pivot in the same direction to divert the water flow toward the upleg also enables the water to flow more freely, thereby mitigating the aforementioned issues with known designs. The upleg is generally offset to one side of the chamber in most syphons and this feature has been found by the applicants to be particularly advantageous in such arrangements.

At least one or each flap may be pivotally mounted or secured to the piston by a hinge, e.g. a respective hinge. At least one or each flap may comprise a flexible member or material o or sheet material or diaphragm. One of the flaps may comprise the flexible diaphragm described above, while the second flap may comprise a second flexible diaphragm. At least one of the flaps or diaphragms may comprise or be formed of a flexible member or material or sheet material. Additionally or alternatively, at least one or each flap may be substantially rigid or comprise substantially rigid material.

The assembly may comprise two diaphragms, for example wherein the diaphragm comprises a first diaphragm and the assembly comprises a further, e.g. a second, diaphragm. The further or second diaphragm may be secured at opposed peripheral portions of the piston, e.g. to provide a hinge about which at least part of the further diaphragm is configured to pivot in use and/or on initiation of a syphonic action.

At least one of the hinges may extend across or substantially across the width or length of the piston. At least one of the hinges may extend across an intermediate portion of the piston. At least one of the hinges may extend across an end or side or peripheral portion of the piston. In some embodiments, the first flap or diaphragm is hinged across an intermediate portion of the piston and the second flap or diaphragm is hinged across an end or side or peripheral portion of the piston, or vice versa. The first and second flaps or diaphragms may be separate or connected together, for example formed in a common sheet of material that may be mounted to or secured to the piston.

At least one of the diaphragms or flaps may be secured to the piston by a strip or rail, for example wherein the flexible member or material or sheet material or diaphragm is received or secured or clamped between the strip or rail and the piston.

At least part of the constraining means may comprise or be provided by a buttress means, for example against which at least a portion of at least one or each flap or flexible diaphragm may be configured to abut or deform, e.g. in use and/or on initiation of syphonic action.

A yet further aspect of the invention provides 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 and a buttress means, wherein the piston comprises a flexible diaphragm configured to deform, in use, on initiation of syphonic action such that at least part thereof to abuts or braces against the butress means.

The syphonic action may be initiated by moving the piston from a first position, e.g. at or adjacent the open end of the chamber, to a second position, e.g. spaced therefrom and/or adjacent the upleg, or by raising the piston from a lowered position to a raised position. The or each flap or diaphragm may be configured to abut the buttress means when, e.g. only when, the piston is in the second or a raised position.

The buttress means may comprise a first bracing surface against which the first flap or diaphragm abuts and/or a second bracing surface against which the second flap or diaphragm abuts. At least one of the bracing surfaces, e.g. the first bracing surface, may comprise a curved or rounded surface, for example to cause or encourage a flap or diaphragm abutting thereagainst to assume a curved configuration. Additionally or alternatively, at least one of the bracing surfaces, e.g. the second bracing surface, may comprise an flat and/or angled surface, for example to cause or encourage a flap or diaphragm abutting thereagainst to assume a flat configuration and/or to extend at an angle, e.g. an acute or right or obtuse angle, relative to the piston.

The chamber and/or buttress means may comprise one or more, e.g. two or more, for example a plurality of, projections that may project into the chamber and/or from a wall or internal surface of the chamber. At least one of the projections may comprise a rib, fin or vane that may be configured to define at least in part a flow channel, e.g. for water to flow, in use, from or through the piston and/or toward the upleg. Preferably, the buttress means comprises a plurality of ribs, fins or vanes defining flow channels therebetween.

One of the projections may comprise the first bracing surface and/or another projection may comprise the second bracing surface. In some embodiments, at least one projection comprises at least part of the first bracing surface and at least part of the second bracing surface. One, e.g. the first, flap or diaphragm may be configured to brace against the one or more ribs, fins or vanes, for example to allow water to flow, in use, through the piston and/or across the other, e.g. second, flap or diaphragm and/or through the one or more flow channels to the upleg.

The chamber may comprise a plurality of ribs between which flow channels are defined, for io example wherein the first diaphragm is configured to brace, in use, against the ribs to allow water to flow across the second diaphragm and/or through the flow channels and/or to the upleg, e.g. when the piston is in a raised position. The ribs may together provide or define a rounded bracing surface, which may be interrupted, against which the first diaphragm may abut, e.g. to cause it to assume a curved configuration. Additionally or alternatively, the ribs may together provide or define an angled bracing surface, which may be interrupted, against which the second diaphragm may abut, e.g. to cause it to extend at an angle relative to the piston and/or to direct a flow of water thereacross and/or toward the upleg.

The chamber may be fluidly connected to the upleg at or on or adjacent a first of its sides, for example wherein one or more of the projections, ribs, fins or vanes and/or the flow channel or channels defined thereby or therebetween may extend from a second side of the chamber to the first side thereof. The chamber may comprise a top wall connected to the upleg, e.g. from which projections may extend into the chamber.

The piston may comprise a substantially planar member, for example a plate, which may comprise one or more openings through its thickness. The piston may comprise a frame including a periphery or peripheral portion and/or at least one cross member. The or each cross member may extend across the periphery or peripheral portion or between two sides thereof. The or at least one diaphragm may be secured along the cross member and/or at or adjacent one or each of its ends. The frame member may further comprise one or more or a plurality or series of beams or ribs that may extend between the cross member and the peripheral portion and/or orthogonal to the cross member, e.g. along at least part of the length of the piston. One or more of the periphery or peripheral portion and/or the one or more cross members and/or the one or more beams or ribs may comprise a wedge shape and/or taper from a narrower side, e.g. on a first side of the piston, to a wider side, e.g. on a second side of the piston. The first side of the piston may comprise the side thereof on which the diaphragm or the flaps are located or mounted or secured and/or the second side of the piston may be the lowermost side thereof. The first side of the piston may comprise the downstream side thereof and/or the second side of the piston may comprise the upstream side thereof.

At least one of the flexible diaphragms and/or the flexible material or sheet material may comprise a flexible and/or resilient plastics material. One or more of the piston, chamber, upleg and/or downleg may comprise a plastics material, for example a rigid plastics material. The assembly may comprise an actuation means, which may comprise a piston rod that may be operatively connected to a lever or a power-driven actuator, such as that which is described in W02015036767 filed by the present applicants, the entire contents of which are incorporated herein by reference.

Another aspect of the invention provides a kit of parts for assembly into an assembly as described above. The kit may comprise one or more of the piston, the diaphragm, which may be provided separately or mounted to the piston and/or one or more components or mouldings incorporating one or more of the chamber, the upleg and/or the downleg.

Another aspect of the invention provides a syphon chamber, e.g. for incorporation into an assembly as described above. The syphon chamber may comprise at least part of the constraining means, for example the buttress means. In one embodiment, the chamber comprises an open bottom, an outlet at or adjacent a first side thereof for fluid connection with an upleg and a plurality of ribs defining flow channels therebetween that extend between the first side and a second side of the chamber.

Another aspect of the invention provides a syphon piston, e.g. for incorporation into an assembly as described above. The piston may comprise at least part of the constraining means, for example a securement at or adjacent its periphery for securing a peripheral portion of the diaphragm thereto. In one embodiment, the piston comprises a frame with a peripheral portion, a cross member extending between two sides of the peripheral portion for secure mounting of a diaphragm therealong and a plurality of beams extending between the cross member and the peripheral portion and orthogonal to the cross member.

Additionally or alternatively, the piston may comprise the diaphragm.

Other aspects of the invention provide a cistern comprising a syphon assembly as described above, a toilet comprising a syphon assembly as described above and a water closet comprising such a toilet and/or cistern.

A yet further aspect of the invention provides a method of flushing or discharging water from the cistern, e.g. using a syphon assembly as described above. The method may comprise initiating a syphonic flush action by moving or raising a piston in a syphon assembly such that a peripheral portion of a flexible diaphragm mounted to the piston is at least partially o constrained to deform in a substantially predetermined manner. Additionally or alternatively, the method may comprise initiating a syphonic flush action by moving or raising a piston in a syphon assembly such that at least a portion of a flexible diaphragm secured at opposed peripheral portions of the piston pivots about a hinge, e.g. to allow water to flow through the piston. Additionally or alternatively the method may comprise initiating a syphonic flush action by raising a piston in a syphon assembly such that two flaps of or mounted to the piston pivot in the same or substantially the same direction, e.g. to a position in which each flap at least partially diverts a flow of water through the piston and/or toward the upleg. Additionally or alternatively, the method may comprise initiating a syphonic flush action by raising a piston in a syphon assembly such that a flexible diaphragm of or mounted to the piston deforms so that at least part thereof abuts or braces against a butress means.

For the avoidance of doubt, any of the features described herein apply equally to any aspect of the invention. For example, the syphon assembly of any of the aforementioned aspects may comprise any one or more features of one or each of the syphon assemblies of any other aspect and/or the method may comprise any one or more features or steps relevant to one or more features of any of the syphon assemblies.

Another aspect of the invention provides a computer program element comprising and/or describing and/or defining a three-dimensional design for use with a three-dimensional printing means or printer or additive manufacturing means or device, the three-dimensional design comprising one or more components of an embodiment of the syphon assembly described above.

A further aspect of the invention provides the computer program element embodied on a computer readable medium.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. For the avoidance of doubt, the terms "may", "and/or", "e.g.", o "for example" and any similar term as used herein should be interpreted as non-limiting such that any feature so-described need not be present. Indeed, any combination of optional features is expressly envisaged without departing from the scope of the invention, whether or not these are expressly claimed. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 is a side view of a syphon assembly according to an embodiment of the invention; Figure 2 is a partial perspective view of the underside of the syphon assembly of Figure 1 shown prior to the initiation of a flush; Figure 3 is a perspective view of the piston of the syphon assembly of Figures 1 and 2 shown prior to the initiation of a flush; Figure 4 is a partial perspective view of the syphon assembly of Figure 1 shown after the initiation of a flush; and Figure 5 is a perspective view similar to that of Figure 3 showing the piston after the initiation of a flush.

Referring now to Figures 1 to 3, there is shown a syphon assembly 1 according to an embodiment of the invention for discharging water from a cistern (not shown). The assembly 1 incorporates an inverted generally U shaped duct 2 having an upleg 20 and a downleg 21, a chamber 3 and a piston 4 movable in the chamber 3. The downleg 21 includes a threaded end 22 and a mounting flange 23 immediately thereabove for mounting to the base of a cistern (not shown) in the normal way.

The chamber 3 is substantially cuboidal in shape with an open bottom 30, a substantially frusto-conical outlet 31 adjacent a first side wall 32 thereof and a top wall 33 that slopes to from a second side wall 34 to the outlet 31. As shown more clearly in Figure 2, the first side wall 32 includes rounded vertical corners 32a and the chamber 3 includes a plurality of ribs 35 projecting from the top wall 33 that define flow channels 36 between them. The ribs 35 and flow channels 36 extend from the second side wall 34 to the outlet 31.

Each of the ribs 35 includes a rounded portion 35a adjacent the outlet 31 that together define a first, rounded but interrupted bracing face 35a. Each of the ribs also includes a triangular cutout adjacent its centre, between the second side wall 34 and the outlet 31, that defines a sloped portion 35b. The sloped portions 35b together define a second, angled bracing face 35b. The portion of the ribs 35 adjacent the outlet 31 also include extension portions 35c that extend from the top wall 33 toward the first side wall 32 to define an end of the flow channels 36 at the entrance the outlet 31.

The piston 4 in this embodiment comprises a substantially planar frame 40 that matches substantially the horizontal cross-section of the chamber 3. Specifically, the frame 40 has a substantially rectangular shape in plan having an end with two rounded corners 40a to match the rounded corners 32a of the first side wall 32 of the chamber 3. The frame 40 is made up of a peripheral portion 41 with a cross member 42 extending across its width and five beam members 43 extending along its length. The peripheral portion 41 defines the periphery of the piston 4 and includes first and second ends 41a, 41b and first and second sides 41c, 41d. The first end 41a of the peripheral portion 41 is joined to the first and second sides 41c, 41d by the rounded corners 40a.

The cross member 42 extends between and is formed integrally with the sides 41c, 41d of the peripheral portion 41 at a position intermediate its ends 41a, 41b, but offset toward the 35 second end 41b. The beam members 43 extend orthogonal to the cross member 42 and are formed integrally therewith and with each end 41a, 41b of the peripheral portion 41. The frame 40 therefore defines a first series of longitudinal slots 44a extending between the cross member 42 and the first end 41a of the peripheral portion 41 and a second series of shorter longitudinal slots 44b extending between the cross member 42 and the second end 41b of the peripheral portion 41. Each of the peripheral portion 41, the cross member 42 and the beam members 43 have a wedge shaped cross-section. More specifically, the peripheral portion 41 has a flat upper surface tapering to a lowermost edge with a cross-section substantially in the form of a right-angled triangle having a straight outer side and a tapered inner side such that an apex of the triangle is lowermost. However, the cross io member 42 and the beam members 43 each have sides that both taper toward a lowermost edge, thereby to form slots 44a, 44b that provide narrowing inlet channels from the cistern into the chamber 3.

The piston 4 also includes a piston rod 45 and a one-way valve means 5, which is in the form of two diaphragms 50, 51 in this embodiment. A first diaphragm 50 is coextensive with the portion of the piston frame 40 extending from and including the cross member 42 to the first end 41a of the peripheral portion 41. The second diaphragm 51 is coextensive with the remainder of the piston frame 40. The first diaphragm 50 is secured along the cross member 42 by a first rail 52 and the second diaphragm 51 is secured along the second end 41b of the peripheral portion 41 by a second rail 53. The first rail 52 has a lower clamping surface that is substantially coextensive with the upper surface of the cross member 42, a rounded upper surface and a hollow cylindrical turret portion 52a extending from the centre of the rounded upper surface. The second rail 53 has a lower clamping surface that is substantially coextensive with the upper surface of the second end 41b of the peripheral portion 41 and a rounded upper surface. Each of the rails 52, 53 includes a pair of resilient clips 54 that releasably engage respective receptacles 46 in each of the cross member 42 and the second end 41b of the peripheral portion 41 of the piston frame 40.

The piston rod 45 is received within the turret portion 52a of the first rail 52 and is secured to a hole 42a in the cross member 42 of the piston frame 40. The piston rod 45 is secured to a lever (not shown) by a C-link 47 to enable the piston 4 to be raised for initiating the syphonic action. Although not shown, the syphon assembly 1 includes a biasing means to urge the piston 4 toward its lowermost position, shown in Figures 1 and 2. The biasing means may be in the form of a compression spring, a weight or any other suitable biasing means.

In use and with the piston 4 is in its lowermost position as shown in Figures 1 and 2, a user operates the lever (not shown) to raise the piston 4. Raising of the piston 4 raises the volume of water within the chamber 3 and upleg 20 over the bight of the U-shaped duct 2, which initiates a syphonic action. Water from within the cistern (not shown) passes through the slots 44a, 44b, urging the diaphragms 50, 51 away from the piston frame 40 and against the bracing faces 35a, 35b of the ribs 35 as shown in Figure 4, which act as a buttress means. As a result, the first diaphragm 50 assumes a curved configuration as shown in both Figures 4 and 5 by virtue of its bracing against the rounded bracing face 35a. The second diaphragm 51 braces against the angled bracing face 35b and assumes an angled configuration, which is also shown in Figures 4 and 5.

Water is therefore able to flow through the first slots 44a across the first diaphragm 50 and out through the outlet 31 to the upleg 20 and out through the downleg 21. Water is also able to flow through the second slots 44b across the second diaphragm 51, through the flow channels 36 between the ribs 35 and into the outlet 31. It will be appreciated that the extension portions 35c of the ribs 35 prevent the first diaphragm 50 from occluding the flow channels 36, thereby enabling an unimpeded flow path for water to flow across the second diaphragm 51 and into the outlet 31. It will be appreciated that if the piston 4 is returned to its lowermost position, the diaphragms 50, 51 will assume a relatively vertical orientation by virtue of the water flow across them. When the water level (not shown) reaches the level of the open bottom 30, the syphonic action is broken in the normal way.

It has been observed that the predetermined deformation of the diaphragms 50, 51 results in less flow restriction than known flushing syphons. This deformation is achieved in this particular embodiment by a combination of securing each diaphragm 50, 51 across the piston 4 and by the ribs 35 against which each diaphragm 50, 51 braces in use. It will be appreciated that each of these features partially constrains the deformation of each diaphragm 50, 51 and contributes to the aforementioned advantages. It has also been observed that the provision of two diaphragms 50, 51 that open in a common direction to divert water flow toward the outlet 31 provides further advantages as described above. It is therefore envisaged that certain embodiments might include rigid flaps (not shown) in place of the flexible diaphragms. It is also envisaged that the diaphragms could be formed in a single sheet, for example secured to the periphery of the piston 4. Other configurations may also be advantageous.

It will be appreciated by those skilled in the art that several variations to the aforementioned embodiments are envisaged without departing from the scope of the invention. For example, the diaphragms 50, 51 need not be secured across the piston 4 by rails 52, 53. It is envisaged that they may instead be secured at two or more locations. The valve means 5 need not include two diaphragms, for example it may include a single diaphragm secured across an intermediate or central part of the piston 4 to provide two flaps opening in io opposite directions. Other arrangements are also envisaged.

It will also 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.

Claims (1)

1. CLAIMSA 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 and a piston movable in the chamber to which a flexible diaphragm is mounted for initiating a syphonic action, wherein the assembly comprises a constraining means configured to at least partially constrain a peripheral portion of the diaphragm such that it deforms in a substantially predetermined manner on initiation of a syphonic action.

   Assembly according to claim 1, wherein at least one peripheral portion of the diaphragm is secured to the piston to provide at least part of the constraining means.

   3. Assembly according to claim 1 or claim 2, wherein the constraining means comprises a buttress means against which at least a portion of the flexible diaphragm is configured to deform when the piston is in a raised position.

   4. Assembly according to any preceding claim, wherein the diaphragm is secured at opposed peripheral portions of the piston to provide a hinge thereacross about which at least part of the diaphragm is configured to pivot, in use, on initiation of syphonic action.

   Assembly according to claim 4, wherein the hinge extends across an intermediate portion the piston.

   6. Assembly according to claim 5, wherein the diaphragm comprises a first diaphragm and the assembly comprises a second diaphragm secured across a peripheral side or end of the piston to provide a further hinge thereacross about which at least part of the further diaphragm is configured to pivot, in use, on initiation of a syphonic action.

   7. Assembly according to claim 6, wherein the diaphragms are configured to pivot, in use, in the same or substantially the same direction on initiation of syphonic action to a position in which each diaphragm at least partially diverts a flow of water through the piston and/or toward the upleg.

   Assembly according to claim 6 or claim 7, wherein the chamber comprises a plurality of ribs between which flow channels are defined, wherein the first diaphragm is configured to brace, in use, against the ribs to allow water to flow across the second diaphragm and through the flow channels to the upleg when the piston is in a raised position.

   Assembly according to claim 8, wherein the ribs together provide a rounded bracing surface against which the first diaphragm abuts to cause it to assume a curved configuration.

   Assembly according to claim 8 or claim 9, wherein the ribs together provide an angled bracing surface against which the second diaphragm abuts to cause it to extend at an angle relative to the piston, thereby to direct a flow of water thereacross toward the upleg.

   Assembly according to any one of claims 4 to 7, wherein the or each diaphragm is secured to the piston by a rail.

   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 and a piston movable in the chamber and including a valve means, wherein the valve means comprises a flexible diaphragm secured at opposed peripheral portions of the piston to provide a hinge thereacross about which at least part of the diaphragm is configured to pivot, in use, on initiation of syphonic action to allow water to flow through the piston.

   13. 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 and a piston movable in the chamber and including a valve means, wherein the valve means comprises two flaps configured to pivot, in use, in the same or substantially the same direction on initiation of syphonic action to a position in which each flap at least partially diverts a flow of water through the piston and/or toward the upleg. 9. to 10. 11. 12.

   14. 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 and a buttress means, wherein the piston comprises a flexible diaphragm configured to deform, in use, on initiation of syphonic action such that at least part thereof abuts or braces against the butress means.

   15. A syphon assembly for discharging water from a cistern substantially as described herein and/or as shown in the accompanying drawings.

   16. A toilet cistern comprising a syphon assembly as claimed in any preceding claim.

   17. A toilet comprising a toilet cistern as claimed in claim 14.

   18. A syphon chamber for incorporation into an assembly according to any preceding claim, the chamber comprising an open bottom, an outlet at or adjacent a first side thereof for fluid connection with an upleg and a plurality of ribs defining flow channels therebetween that extend between the first side and a second side of the chamber.

   19. A computer program element comprising and/or describing and/or defining a three-dimensional design for use with a three-dimensional printing means or printer or additive manufacturing means or device, the three-dimensional design comprising an embodiment of the syphon chamber according to claim 14.

   20. A syphon piston for incorporation into an assembly according to any preceding claim, the piston comprising a frame with a peripheral portion, a cross member extending between two sides of the peripheral portion for secure mounting of a diaphragm therealong and a plurality of beams extending between the cross member and the peripheral portion and orthogonal to the cross member.

   21. A computer program element comprising and/or describing and/or defining a three-dimensional design for use with a three-dimensional printing means or printer or additive manufacturing means or device, the three-dimensional design comprising an embodiment of the syphon piston according to claim 16.

   22. A method of flushing or discharging water from the cistern, the method comprising initiating a syphonic flush action by moving or raising a piston in a syphon assembly such that a peripheral portion of a flexible diaphragm mounted to the piston is at least partially constrained to deform in a substantially predetermined manner.

   23. Method according to claim 20, wherein the syphon assembly comprises an assembly according to any one of claims 1 to 13.

   24. A method of flushing or discharging water from the cistern substantially as described io herein and/or as shown in the accompanying drawings.