GB2270528A - Dual-flush facility for syphonic flushing cistern - Google Patents

Abstract

A Siphon assembly for a W.C. flushing cistern has a venting aperture (32) at an intermediate level in a sidewall of the siphon chamber (18) to provide a reduced flush volume when open (see GB 2213846A). A closure element (34) is pivoted on the chamber wall, conveniently by a stud (36), so that it is permanently attached but can readily be moved from open to closed positions at choice. To maximise the venting effecting the aperture may have a horizontal full width upper edge, e.g. it may be shaped as an inverted triangle. <IMAGE>

Description

SIPHON ASSEMBLY FOR FLUSHING CISTERNS This invention relates to siphon assemblies for flushing cisterns, said assemblies comprising an inverted generally U shaped duct having an up leg and a down leg the up leg being provided with an enlarged chamber having a lower end open to the interior of the cistern in use and the down leg forming an outlet from the cistern in use for delivery of flushing water to an associated W.C pan or the like. A vertically displaceable piston.

commonly incorporating a flexible diaphragm of. for example, rubber or plastics material acting as a one way valve. is movable in said chamber to initiate a siphonic flushing action.discharging water from the cistern in operation in well known manner. Such a siphon assembly is hereinafter referred to as a siphon assembly of the kind described" Current practice attaches increasing importance to economy in water use, there have been substantial increases in the cost of water supply in recent years, many supply undertakings are considering metering supplies so that charges are directly related to usage, and building and other regulations are making use of economical appliances mandatory for new installations.

Modern designs of W.C. pans have been evolved which will flush efficiently with a much less volume of water than older designs and U.K. building regulations are being brought in or under active consideration imposing a requirement that all new W.C. installations shall operate with a maximum flush volume of 7*5 litres of water instead of the 9 litre volume which was common for older patterns of W.C. Siphon assemblies therefore need to be designed to deliver this lesser volume There will continue to be a substantial market for siphon assemblies for the older patterns of W.C. already installed for many years to come.For economy of manufacture and economy of stocking by builders merchants and the like there is therefore a need for a siphon assembly which can readily be adapted to deliver either a higher or a lower flush volume e.g. can be selectively changed over to deliver either 9 or 7 1/2 litres. One proposal for such an adaptable siphon assembly is described in GB-A-2213846 involving the provision of an aperture at an intermediate level in a side wall of the up leg chamber which can be selectively closed by inserting a removable snap fitting sealing plug.With the plug inserted the siphonic action will continue until the water level in the cistern falls below the open bottom of the chamber, whereas when the plug is removed the siphonic action will cease when the cistern water level falls below the level of the aperture, the latter allowing air to enter the chamber and so terminate the siphonic action when a lower volume of flushing water has been delivered The object of the present invention is to provide an adaptable siphon assembly of the kind described which is of simple construction, economical to manufacture, and in which change over between greater and lesser flush volume can be made easily and reliably.

According to the invention there is provided a siphon assembly of the kind described wherein a venting aperture is defined by a side wall of the chamber at a predetermined intermediate level to provide a reduced flush volume characterised in that said assembly further includes a closure element mounted on the chamber for selective movement between an open position at which said aperture is unobstructed and a closed position at which said element overlies the aperture to substantially prevent fluid flow therethrough.

Conveniently the closure element is a flap or shutter pivotally mounted on the chamber wall for angular movement between the open and closed positions.

Alternatively. it is contemplated that the closure element is a shutter mounted in sliding engagement with formations of the chamber wall so that it coacts with the aperture in the manner of a slide valve For some applications more than one aperture might be provided. either on a common level to enhance the effective cut-off of the siphonic action giving the lower volume flush delivery or possibly on different levels so that a selection from more than two different flush volumes can be made. A common closure element may be arranged to coact with two or more such apertures, its range of movement permitting positioning to close all or some of them, or some one or more of the apertures may be provided with individual coacting closure elements.

While circular or other shapes of aperture may be employed. it is preferred that an aperture bounded by a straight upper edge which is horizontal in the position of use, and which preferably extends the full or maximum width of the aperture, is provided to maximise the venting effect as soon as the water level drops to or below said edge, thus a rectangular aperture, or a triangular aperture base uppermost may be used.

An example of the invention with certain modifications thereof is now more particularly described with reference to the accompanying drawings. wherein: Figure 1 is a side elevation of a siphon assembly, Figure 2 is a part sectioned underneath view of a portion of the chamber and piston of said assembly; and Figures 3 and 4 are similar part sectional views of modified constructions.

A siphon assembly 10 (Figure 1) comprises a conventional inverted U-shaped duct formed as an assembly of plastics mouldings. A down leg 12 of the duct will be secured in known manner by a screw collar in the discharge opening of an associated W.C. cistern (not shown) in use, its upper end being joined to the upper end of a parallel up leg 14 by a top joint portion 16.

The lower part of leg 14 is widened to form a substantially rectangular chamber 18 having vertical side walls and a downwardly directed open mouth which will locate just above the bottom of the cistern in use.

A piston sub-assembly 20 indicated at its lowermost position in broken lines in Figure 1 and shown only in part in Figure 2 is located within chamber 18. Sub assembly 20 is of generally conventional construction including a rigid plastics support portion 22 on which rests a flexible diaphragm 24 acting as a one-way valve so that upward displacement of the piston lifts water up the up leg 14 to initiate the siphonic action but the downward return stroke is unobstructed. A rod 26 of the sub--assembly extends through a top wall of chamber 18 alongside up leg 14 and is actuated by a pull hook 28 which will be connected to a flushing lever of the cistern in the usual way.

The front side wall of chamber 18 is provided with a vertically extending planar portion 30 in which is formed an aperture 32 shaped as an equilateral triangle, base uppermost so that the upper bounding edge of aperture 32 extends horizontally across its maximum width. Aperture 32 is at an intermediate height, in this example it is positioned with said upper edge approximately halfway up the chamber 18 A closure element in the form of a generally rectangular shutter 34 is mounted by means of a pivot stud 36 in face-to face relationship with the outer surface of flat wall portion 30 immediately below aperture 32 so that it can be swung from the open position shown in full lines in Figure 1 in which it is clear of aperture 32 to a closed position shown by broken lines in which it overlies and shuts off the aperture.

Shutter 34 is preferably formed from resilient plastics material and may be moulded to include a continuous edge rim or lip (as seen better in Figure 3) for sealing abutment with the chamber side wall surface so that it has substantially fluid tight engagement around the aperture in the closed position. A modified form of shutter 34a is shown in Figure 4 having a dished cross section so that it is outwardly convex to urge its edges resiliently into sealing contact with said wall surface.

With the closure element or shutter 34 in the closed position the siphonic action initiated by operation of the piston sub-assembly 20 will continue until the water level in the cistern drops to the level A (Figure 1) at which air will be admitted through the open bottom of chamber 18, thus the maximum flushing volume, e.g. 9 litres, will be delivered.

If the closure element or shutter 34 is turned to the open position the flushing action will terminate when the water falls to the higher level B of the upper part of aperture 32, air entering through the latter terminating the siphonic action: thus a lesser volume of flushing water, e.g. 7.5 litres, will be delivered.

As the closure element is permanently attached to the assembly there are no loose plugs or stoppers to be dislodged. lost or mislaid and the change over to select the desired flush volume is very easy to make without involving use of any tools and can even be easily done when the siphon assembly is mounted in the cistern.

A common siphon assembly can therefore be stocked and supplied for use with older installations requiring the maximum flush volume or newer installations which will operate with the lesser volume and the change over can be made on site in a few seconds according to requirements. Moreover the facility for change over is.

as it were, built in to the assembly in a permanent manner so that it is always available; thus, even with the older installations, a user can experiment with the two different settings and, if he finds that the lesser volume flush is effective, can leave the aperture 32 open accordingly to gain the benefits of the consequent water economy. There is also the possibility of changing over to the lower flush volume in times of drought or other water shortage which is much more satisfactory than resorting to such practices as placing a brick in the cistern.

To facilitate the moulding of the chamber 18 in To facilitate the moulding of the chamber 18 in plastics it is preferred that the surface of the wall portion 30 surrounding the aperture is co-planar with the remaining parts of the associated chamber side wall which will mean that the inner head of the securing stud 36 may project somewhat into the chamber. To accommodate this the piston support portion 22 and diaphragm 20 may be formed with a small notch or cut-out as indicated at 40 in Figure 2 so that the stud does not obstruct the reciprocal movement of the piston sub-assembly.

Conveniently each of the two side edges of portion 22 and diaphragm 20 will have the notch or cut-out so that the piston sub-assembly cannot be inserted wrong way round in the chamber.

In the modified construction shown in Figures 3 and 4 said wall portion 30 is formed to project outwardly of the remaining part of the associated side wall so that the stud 36 does not project into the path of the piston sub-assembly.

Other forms of closure element are contemplated, for example a flap hinged along one edge to be swung about an axis coincident with or parallel to the outer face of the chamber side wall between open and closed positions possibly with some kind of snap-engaging or other catch to retain it securely when closed. Alternatively a sliding shutter might be used movable in guide rails or other formations of the chamber side wall for nonpivoting movement between the open and closed positions.

Claims (13)

1. A siphon assembly of the kind described wherein a venting aperture is defined by a side wall of the chamber at a predetermined intermediate level to provide a reduced flush volume characterised in that said assembly further includes a closure element mounted on the chamber for selective movement between an open position at which said aperture is unobstructed and a closed position at which said element overlies the aperture to substantially prevent fluid flow therethrough.

2. An assembly as in Claim 1 wherein the closure element is a flap or shutter pivotally mounted on the chamber wall for angular movement between the open and closed positions.

3. An assembly as in Claim 1 wherein the closure element is a shutter mounted in sliding engagement with formations of the chamber wall so that it coacts with the aperture.

4. An assembly as in Claim 1, 2 or 3 including more than one said aperture.

5. An assembly as in Claim 4 wherein the apertures are on a common level to enhance the effective cut-off of the siphonic action giving the lower volume flush delivery.

6. An assembly as in Claim 4 wherein the apertures are on different levels so that a selection from more than two different flush volumes can be made.

7. An assembly as in Claim 4, 5 or 6 wherein a common said closure element is arranged to coact with two or more of said apertures, its range of movement permitting positioning to close all or one or more of them.

8. An assembly as in Claim 4, 5 or 6 wherein one or more of said apertures are provided with individual coacting closure elements.

9. An assembly as in any preceding claim wherein the or one of the said apertures is bounded by a straight upper edge which is horizontal in the position of use, and which extends the full or maximum width of that aperture to maximise the venting effect as soon as the water level drops to or below said edge.

10. An assembly as in Claim 9 wherein said aperture is rectangular.

11. An assembly as in Claim 9 wherein said aperture is triangular with its base uppermost.

12. An assembly as in any preceding claim wherein the closure element includes an edge rim or lip for resilient sealing contact with a wall surface surrounding the related aperture.

13. A siphon assembly substantially as hereinbefore described with reference to and as shown in the accompanying drawings.