GB2329398A - Syphon assembly for flushing cistern - Google Patents

Abstract

Syphon assembly has conventional U-shaped duct with up leg 10 carrying an open-bottomed syphon chamber 14 and down leg 12 leading from the associated cistern, with a known piston assembly 18 operated by a vertical pull rod 20 being operable to initiate syphonic discharge. Air break passages 32 in the top of chamber 14 and partly surrounding rod 20 are sealed when the piston is at its lowermost position by a seal washer 40 carried on the rod. The arrangement provides a dual volume flush facility, if the piston is dropped immediately a maximum volume flush is provided, this being the default condition, whereas if the piston is deliberately held raised the syphonic action will cease after discharge of a lower volume as soon as the water level drops to that of the passages 32 as air will then enter the chamber to break the syphon.

Description

SYPHON ASSEMBLY FOR FLUSHING CISTERNS This invention relates to syphon assemblies for flushing cisterns, said assemblies comprising an inverted generally U-shaped duct having an up leg and a down leg. The up leg is provided with an enlarged chamber having a lower end open to the interior of the cistern in use and the down leg forms an outlet from the cistern in use for delivery of flushing water to an associated WC pan or other sanitary facility. A vertically displaceable piston, commonly incorporating a flexible diaphragm acting as a one-way valve, is moveable in said chamber to initial syphonic flushing action in well known manner. Such a syphon assembly is hereinafter referred to as "a syphon assembly of the kind described".

Economy in the use of water is assuming ever increasing importance and requirements for efficiency and minimum water consumption in sanitary installations is becoming mandatory in many countries including regulations regarding the volume of water consumed for each flushing cycle. Modern designs of WC pan and the like have been evolved which will flush efficiently with a much less volume of water than older designs, and there is now a call for provision of dual flushing whereby the user can select either a full flush or a flush of lesser volume as required and with a view to maximum water economy. Various forms of syphon assemblies of the kind described incorporating provision for dual flushing are known.

Regulations are now in contemplation, at least in the UK, requiring dual flush systems to default to the maximum volume full flush, some special operation having to be carried out to consciously select low volume flush. If a low volume flush is initiated inadvertently or by default, it may not clear the pan or the like so that the user, or the next person to use the facility carries out a repeat flush, often at full volume, resulting in extra wastage of water rather than any saving.

The object of the invention is to provide a syphon assembly of the kind described with a dual flush facility in which the full flush is the default condition in a particularly simple and economic manner and which is durable and reliable in use.

According to the invention there is provided a syphon assembly of the kind described characterised in that there is a passage between the chamber and the interior of the cistern in use at a predetermined level substantially above that of the lower end of the up leg but substantially below the water level in the cistern when full, and a pull rod for operating the piston and which passes through the chamber wall carries a sealing formation which co-acts with said passage to close it when the piston is at its lowermost position, whereby in use a maximum volume flush can be effected by raising the piston and allowing it to return to the lowermost position without delay, but a lesser volume flush can only be effected by holding the piston in a raised position until the water level drops below the passage opening allowing air to enter the chamber and so causing the syphonic action to end.

Conveniently, said passage is defined in wall structure of the chamber in part surrounding relationship or in close proximity to the pull rod, the sealing formation seating in or against a surrounding face of said passage opening at said lowermost position.

Preferably a spring or other resilient means, for example a compression spring located on the piston rod within the chamber urges the piston and pull rod to said lowermost position for fluid tight sealing of the passage.

An example of the invention is now more particularly described with reference to the accompanying drawings wherein: FIG. 1 is a perspective view of a syphon assembly incorporating the invention.

FIG.2 is a vertical section thereof with a piston and pull rod in a lowermost position, and FIG.3 is a like section showing the piston and pull rod in a raised position.

The assembly comprises a generally conventional inverted U-shaped duct assembled from plastics mouldings to have an up leg 10 and a down leg 12. Up leg 10 has a substantially enlarged lower portion forming a syphon chamber 14, the bottom of which is open to the interior of a cistern (not shown) in use in close spaced relationship to the cistern bottom wall 16 (Figs.2 and 3).

The bottom end of down leg 12 is operatively secured in a bottom opening of wall 16 to form an outlet from the cistern connected to a WC pan or the like in known manner.

A piston assembly 18 of known kind is located for vertical displacement within chamber 14 by means of a pull rod 20 extending through a guide formation 22 in roof part 24 of chamber 14. Rod 20 is operatively linked to a flushing lever or other manual operating member of the cistern (not shown) in conventional manner by means of a coupling 26 alongside the upper part of up leg 10.

Piston assembly 18 includes a lowermost diaphragm support frame 28 secured to rod 20, and a flexible sheet rubber, plastics or similar diaphragm 30 located against the upper face of frame 28 with its edges in sealing engagement against the inner walls of chamber 14 but deflectable upwardly on downward motion of the piston assembly to act as a one-way valve in conventional manner for initiating syphonic action when the piston is raised.

Moulded into said roof part 24 co-axially with guide formation 22 is a pair of part circular air break through passages 32, their lower ends opening into the upper part of chamber 14 and their upper ends opening through a horizontal face of the chamber structure to the interior of the cistern in use at an intermediate level indicated at 34 in FIGS.2 & 3, substantially above the level of the bottom edge of chamber 14 but substantially below the normal maximum water level in the cistern, indicated eg at 36 in those figures.

The exposed upper end of pull rod 20 carries a collar 38 below which is a rubber or similar sealing washer 40 which seats in fluid tight engagement against the chamber wall face to close passages 32 when piston assembly 18 is at its lowermost position shown in FIG.2.

A compression spring 42 is located on rod 20 within chamber 14 between piston assembly 18 and guide formation 22 urging the piston and rod downwardly to their lowermost position.

In operation depression of the operating lever or the like to raise piston assembly 18 and so initiate syphonic flushing flow in known manner with release of the lever as soon as or shortly after flushing has commenced will return the piston assembly and rod 20 to their lowermost position aided by the action of spring 42 so that passages 32 are shut off before the water level in the cistern has dropped past level 34. A full flush will occur because the syphonic action will continue until the cistern is substantially emptied and air can enter the bottom of chamber 14.

For lower volume flushing the user must consciously decide to hold the operating lever or the like to keep piston assembly 18 and rod 20 raised in the conditions shown in FIG.3 or at least partly raised as shown in FIG.1 until the water in the cistern drops past level 34. When this occurs, air can enter chamber 14 through the open passages 32, breaking the vacuum and terminating the syphonic action at or near that level providing a lower volume flush with the cistern only partly emptied.

For some applications a passage or passages might be incorporated in pull rod 20 eg it could be a tubular rod having a lower opening into chamber 14 above piston assembly 18 and an upper opening only exposed when the rod is raised and co-acting with a sealing formation on the top of the chamber when the rod is at the lowermost position.

Claims (6)

1. A syphon assembly of the kind described characterised in that there is a vertically extending passage opening into the chamber at its lower end and into the interior of the cistern in use at its upper end at a predetermined level substantially above that of the lower end of the up leg but substantially below the water level in the cistern when full, a pull rod for operating the piston and which passes through the chamber wall, and a sealing formation associated with the pull rod which co-acts with said passage to close it when the piston is at its lowermost position, whereby in use a maximum volume flush can be effected by raising the piston and allowing it to return to the lowermost position without delay, but a lesser volume flush can only be effected by holding the piston in a raised position until the water level drops below the passage opening allowing air to enter the chamber and so causing the syphonic action to end.

2. An assembly as in Claim I wherein said passage is defined in wall structure of the top of the chamber in part surrounding relationship or in close proximity to the pull rod, the sealing formation seating in or against a face of said wall structure surrounding said passage opening at said lowermost position.

3. An assembly as in Claim 1 wherein said passage is defined within the pull rod, said sealing formation being located by the chamber wall to close the upper end of the passage at said lowermost position of the piston.

4. An assembly as in Claim 1, 2 or 3 including resilient means urging the piston and pull rod to said lowermost position for fluid tight sealing of the passage.

5. An assembly as in Claim 4 wherein the resilient means is a compression spring located on the piston rod within the chamber.

6. A syphon assembly substantially as hereinbefore described with reference to or as shown in the accompanying drawings.