GB2336605A

GB2336605A - Cistern outlet valve

Info

Publication number: GB2336605A
Application number: GB9907783A
Authority: GB
Inventors: Douglas Robert David Frost
Original assignee: John Blackborow
Current assignee: John Blackborow
Priority date: 1998-04-21
Filing date: 1999-04-07
Publication date: 1999-10-27
Also published as: GB9907783D0; EP1073802A1; AU3340299A; WO1999054563A1

Abstract

An improved cistern valve, particularly for flushing of W. C.s, comprises a housing (1A) having a upper portion (8) and a lower portion (31A), a upwardly movable main valve assembly (30) within the housing and forming therewith a variable volume upper chamber (11) and lower chamber (32A), a first vent means (9, 42) between the upper chamber (11) and the lower chamber (32A) and an outlet (15) leading down from lower housing portion (31A), which portion (31A) contains a seat (33) for the main valve assembly (30) at the entry (1) to the outlet (15) so that in the lowered position of the main valve assembly the outlet is blocked against the ingress of fluid in which the device is immersed, a central stem (19), extending upwardly from the main valve assembly (30) and actuable remotely from the upper housing (8) to raise the main valve assembly (30) of its seat, the wall of the lower portion (31A) of the housing having apertures (31B) above the seat (33), whereby on raising the main valve assembly immersion fluid can enter the outlet (15), the net upward buoyancy force acting on the assembly (30) thereby causing it to rise to the top of the upper chamber (11) and permit full flow of immersion fluid through the outlet and, on its substantially complete discharge, the cessation of flow allowing the main valve assembly to revert to its seated position, characterised in that a second vent means (17, 23, 47) is provided in the upper chamber (11) for ejection of fluid from the upper chamber by the rising main valve assembly (30) and in that air can penetrate into the upper chamber via the first and second vent means during descent of the main valve assembly, the upper housing portion (8) having a central hollow boss (28) through which the central stem (19) extends and an annular pocket (12) being formed as a recess bound by a wall (12A) extending downwardly from the upper surface (26) of the main valve assembly and joined at its lower end to the stem (19), the boss (28) extending into this pocket which acts a water trap labyrinth.

Description

2336605 P. 1099

DESCRIPTION

CISTERN OUTLET VALVE This invention relates to an outlet valve and is primarily intended to provide a quick responding, easily operable fast flowing valve for emptying or partly emptying cistems and other types of liquid storage containers. It is particularly, although not exclusively, applicable to being used to enable the amount of water used for flushing domestic toilets or W.C.'s to be substantially reduced.

For a great many years flushing toilets have been in existence, and the W. C. in one form or another, is common place in all modem homes. With the conventional low flush or close coupled toilet cistern and pan, the means for achieving the flushing action consists either of a siphon (which at the present for the U. K. is the only device that meets the water byelaws) or one of a number of non-siphon type valves used extensively on the European continent and elsewhere in the world. The situation as regards U. K. acceptance of nonsiphon type outlet devices is presently under review and it is expected in the foreseeable future that both siphon and non-siphon type outlet devices will be used in the U. K.

These non-siphon, direct or "flapper" type valves have a valve plate or member which covers and seals the outlet to prevent water from escaping unintentionally. Both the siphon and the direct type valve have a threaded 2 outlet pipe which extends downwards through the bottom of the cistern into which it is fixed by a bulkhead fitting. It is then connected to the toilet pan either directly (close coupled) or by a short length pipe.

With the sole means of flushing or cleaning the pan being the water discharge from the cistern, the efficiency of the flush is mainly dependent upon the flow rate. Most siphons do not have a good flow rate and require a considerable amount of water to achieve a satisfactory flush. They are sensitive to changes in water level setting and most do not perforTn satisfactorily below a medium level setting. With some installations, particularly with restricted galleries and uneven distribution around the rim of the pans, the flow rate and flushing performance are so low that in some cases more than one flush is necessary.

Non-siphon type valves generally achieve greater flow rates and with the kinetic energy of the water entering the pan approximately doubling for a 50% increase in flow rate, less water is required for achieving an effective flush. In fact the performance of most U. K. toilet pans could be appreciably improved by replacing the siphon with a direct type flush valve and also some existing installations elsewhere could accommodate even higher flow rates than are generally available with existing flush valves. For new installations, by designing the galleries and contours of the pan to accommodate the higher flow rate and performance of outlet valves of this type, the quantity of water required for effective flushing can be substantially reduced. Moreover the higher efficiency of the valve will enable simplification of the pan design e.g. open rim instead of box rim enables wider moulding tolerance and allows considerable cost savings to be achieved in manufacture.

3 An objective of the invention is to enable the amount of water required for effectively flushing W.C.s to be substantially reduced (e.g. for U. K. , from 7 to 4 to 4.5 litres full flush.).

It is also an object of this invention to provide an easily operable, high performance, low cost fluid discharge valve with excellent reliability and high sealing integrity to increase and enhance the performance of both new and existing W.C.s.

It is a further objective of this invention to provide a full or a variable flusk a so called interruptible or partial flush valve (typically on an interrupted or partial flush, only using 2 to 2.5 litres instead of 7 litres - a saving of 4.5 to 5 litres on every short flush. (Nine out of ten flushes require only short or partial flushes.). Also it is an objective to provide a convenient overflow means through the valve, a so-called integral overflow.

Accordingly, the invention provides a device for immersion in a fluid in a cistern, which comprises a housing having an upper portion and a lower portion, an upwardly movable main valve assembly within the housing and forming therewith a variable volume upper chamber and lower chamber, a first vent means between the upper chamber and the lower chamber and an outlet leading down from lower housing portion, which portion contains a seat for the main valve assembly at the entry to the outlet so that in the lowered position of the main valve assembly the outlet is blocked against the ingress of fluid in which the device is immersed, a central stem, extending upwardly from the main valve assembly and actuable remotely from the upper housing to raise the main valve assembly of its seat, the wall of the lower 4 portion of the housing having apertures above the seat, whereby on raising the main valve assembly immersion fluid can enter the outlet, the net upward buoyancy force acting on the assembly thereby causing it to rise to the top of the upper chamber and permit full flow of immersion fluid through the outlet and, on its substantially complete discharge, the cessation of flow allowing the main valve assembly to revert to its seated position, characterised in that a second vent means is provided in the upper chamber for ejection of fluid from the upper chamber by the rising main valve assembly and in that air can penetrate into the upper chamber via the first and second vent means during descent of the main valve assembly, the upper housing portion having a central hollow boss through which the central stem extends and an annular pocket being formed as a recess bound by a wall extending downwardly from the upper surface of the main valve assembly and joined at its lower end to the stem, the boss extending into this pocket which acts as a water trap labyrinth.

It will be appreciated that on replenishment of the immersing fluid an additional downward force acts on the main valve assembly, mostly due to pressure on top of the main valve assembly, thus providing additional seating force.

The central upwardly extending stem is preferably a hollow stem protruding above the normal full level of the fluid in the cistern and so provides a convenient and efficient discharge route for fluid to the outlet, should the fluid level rise above the desired normal full level. Thus an overflow route is provided through the outlet. The invention is more specifically described below with reference to a hollow stem although it will be appreciated that this is not essential.

The first vent means may conveniently be a restricted passage or pressure balance aperture between the upper and lower chambers.

The second vent means through which the fluid is ejected from the upper chamber as the main valve assembly rises may be, for example, an annular ejection port or siphon duct and may additionally include a pressure balance aperture, non-return valve or vent hole to assist fluid flow back into the upper chamber on refilling of the cistern.

To provide an interruptible flush facility, the actuating device can be made to engage with the hollow stem to enable it and the main valve assembly with which it forms an integral part to move downward sufficiently to cause re-seating or closing of the valve at any level below the full level.

On cessation of flow of the immersing fluid into the outlet following either emptying of the cistern or the discharge halted at an intermediate level, air or immersing fluid and mainly air enter the upper chamber mainly via the second vent means, e.g. a siphon duct or an annular channel between the upper housing boss and central stem and/or to a lesser extent the air/immersing fluid enters via the first vent means. At the end of the full flush mode, the main valve and a hollow stem assembly descend to the seated position (the valve closed) under gravity. In the case of discharge being interrupted, on the other hand, at any intermediate level, the main valve and hollow stem assembly has to be pressed down to the seated position.

6 With the valve reseated either following a full flush or an interrupted flush, as refilling takes place, some immersing fluid penetrates the upper chamber via, e.g. the pressure balance aperture and immersing fluid then either totally or partly fills the upper chamber. In any case whether the upper chamber contains air, immersing fluid or a combination of both, pressure due to the head of immersing fluid presses down on top of the main valve assembly (piston) thereby increasing the seating force.

The immersing fluid for W. C. outlet valves is of course water and the invention will here after be described with reference to water for convenience.

For a better understanding of the invention, the main embodiments will be described, by way of example only, with reference to the accompanying drawings, wherein:

Figure 1 shows a part sectional arrangement of a device according to one embodiment of the invention, being a first single flush valve with an interruptible discharge, the valve being in the closed position; Figure 2 shows a variation of Figure 1 of a single flush valve with interruptible discharge, again the valve being in the closed position; Figure 3 shows a sectional arrangement of a third device of the invention, being a single flush valve in the open position; and j 1 1 7 Figure 4 shows a sectional arrangement of a fourth single flush discharge valve embodiment of the invention, with provision for interruptible discharge, the valve being in the closed position.

Figure 1 shows a cistern outlet/flush valve indicated generally at IA and sealed by a seal 3 and nut 2 into an outlet at the bottom of a cistern 14. The valve IA is immersed in water to a set level 25 and the valve is closed with a main seal 5 sealing its outlet base 1 against a seat 33 in a lower portion of the valve housing to prevent the ingress of water from the cistern. The valve housing has an upper chamber 11, which is filled with water and is in free communication with the water in the cistern via a port 17 and siphon ejection duct 16. In the closed position the main valve assembly 30, which comprises a piston body 6 and a hollow stem 19, is kept in place by the weight of the assembly and the pressure of water on top of the piston 26.

Spaces 31B between the supporting pillars 31A above the seat 33 provide communication between the cistern water and water in the lower annular region 32A inside the lower valve housing. As seal 5 is lifted off seat 33, cistern water can therefore discharge through outlet 1, 15.

The upper chamber 11 is defined between the extension wall 1 IA of the upper part of the valve housing, a hollow central boss 28 and the upper surface 26 of the movable valve or piston assembly 30. The main valve assembly 30 moves up and down inside the upper chamber and is sealed by means of seal 7 which remains in contact with the interior of wall 11 A.

8 The hollow body 6 of the main valve or piston assembly 30 defines from its upper central region a downwardly extending annular wall 12A which is joined at its lower end to a hollow central stem 19. Stem 19 extends fully through the housing from its lower outlet end 1 to above the water level 25 in the cistern. Between wall 12A and stem 19 is defined an annular pocket 12, whose finiction is described later.

Operation of the valve is achieved initially by lifting the main valve assembly (piston) 30 including its hollow stem off its seat 5, 33. This is carried out by either a lever or pull up knob engaging with a collar 10 attached to hollow stem 19 and raising the said assembly above the valve seat sufficient to allow water to enter and fill the entrance to the outlet 15. When this has taken place, the pressure on the underside of the lower surface of the piston assembly achieves sufficient upward force to overcome the downward forces on the piston and for the piston to start to rise, whilst at the same time ejecting and pushing water from the upper chamber via the tube/duct 16. With the tube containing water, pressure on top of the piston 26 is at the same pressure as the pressure at the depth of water below the surface 25 and therefore does not increase to the pressure at a depth level with the bottom edge 27 of the siphon/ejection duct (as would be the case if the upper chamber contained air).

Once the valve has been raised above the seat by an amount sufficient to overcome the forces acting down on the main valve and hollow stem assembly 6, 19, the said assembly 30 rises to the top of the upper housing 8 displacing the water which is discharged from the bottom edge 27 of duct 16 into the cistern. With the valve fully open, water is discharged through the 9 outlet 1, 15 and into the toilet pan. The main valve assembly (piston) remains in the fully opened position during discharge mainly due to the water pressure underneath the piston being greater than the pressure on top of it.

During the early stages of discharge, the piston remains on top of the upper housing 8 and the water level in the cistern falls rapidly from its filling level 25. At the point when the level has fallen level with a vent hole 13 near the top of duct 16, air begins to enter the ejection duct 16, slowly displacing water from it. This initially does not affect the assembly (piston) 30, since there is sufficient buoyancy keeping it at the top of the housing 8 and even when the level has fallen below the lower flange 31 of the upper housing, the ingress of air does not significantly increase since it is only as the level is approaching the empty position that the weight of the piston exceeds the buoyancy force and the only additional path for the ingress of air is via a pressure balance hole 9 between the upper and lower chambers inside the housing. No air can enter through the clearance gap between the hollow stem 19 and the bore of the upper housing boss 28 as the annular pocket 12 in the piston contains water and in the raised position forms a simple labyrinth which acts as a very effective water trap. Accordingly only when the water level has fallen below the bottom edge 27 of ejection duct 16 is there a rapid in-rush of air to the upper chamber to release the piston, allowing it to descend and reseat.

With the valve just having reseated, the upper chamber 11 and ejection duct 16 initially contain air, and refilling commences. As the water level rises and becomes level with the bottom edge 27 of the ejection duct, water in the cistern rises at a slightly greater rate than inside the ejection tube due to the air inside being slightly compressed by restriction to the flow of air out through the vent hole 13. As refilling continues, the level reaches the bottom flange 31 and water enters the space between the upper housing 8 and the piston body 6 with air above the water being displaced through the pressure balance hole 9 into upper chamber 11 and vented through vent hole 13. Some air will of course leak through the very small gap in the piston ring 7, but this is negligible compared to the pressure balance hole.

Refilling continues, the water level rises in the gap between the piston and bore of the upper housing and penetrates the upper chamber 11 via the pressure balance hole. Water continues to flow into the upper housing until it is full, the air being displaced and vented through vent hole 13. Filling continues and the water level rises above the upper housing and up until the filling level 25 is reached - this being the point at which a conventional control float (not shown) shuts off the water inlet into the cistern.

With the cistern filled the valve is ready for use and on lifting the collar 10 to provide the initial part of the opening stroke, the valve will automatically then fully open in the manner described in the foregoing. If it is decided that the full flush is not required, the discharge can be stopped, i.e. interrupted, by closing the valve. This interruption may be achieved by pressing down on the collar 10 and stem 19 to cause the valve to reseat bringing the main seal 5 down onto the valve seat 33. The full downward stroke may be required to achieve this and in the process water readily flows through the ejection duct 16 into the upper chamber 11. With operation of the valve being either a pull up knob or conventional lever, interruption involves 11 the reverse of the action required to open the valve, i.e. fully pressing down on the knob, or rotating the lever in the opposite direction.

In the event of the inlet valve not shutting off when the cistern has filled to the set water level, the water level will continue to rise until it reaches the top edge 34 of the hollow stem 19 and from then on downwards through the hollow stem and into the toilet pan. The hollow stem (overflow) can be made capable of handling the full flow of a failed water inlet valve.

Figure 2 shows an arrangement functionally and configurationally similar to Figure 1, in which the ejection duct 16 has a non return valve 18 instead of the vent hole 13. With this arrangement, the non return valve gives flinctionally marginally improved ease of opening and quicker filling of the upper chamber 11 during refilling of the cistern.

With the cistern filled to the set level 25, the valve is operated as before by the actuation device (lever or knob) engaging with the collar 10 and hollow stem 19 to raise the main valve and stem assembly (piston) 30, sufficiently for the force due to water pressure underneath the piston to raise the said assembly to the top of the upper housing. Water displaced from the upper chamber 11 both during the initiating lift and due to the buoyancy of the piston during the remainder of the upward stroke is again pushed into the ejection duct 16, but this time some of the water flows through the non return valve 18 and the rest of the water is discharged into the cistern from the bottom of the duct 27 as for Figure 1. As before when the level has fallen to just below the ejection duct outlet 27, air enters the upper chamber and the piston rapidly descends and reseats. At an earlier stage during emptying, 12 unlike with the vent hole at Figure 1, no air enters the ejection duct 16 (there is no flow through non return valve 18) until the bottom of the duct 27 is uncovered. Up to this point the leg of water in the duct applies a suction helping to further assist with keeping the piston at the top of the upper housing.

After the valve has reseated and refilling commenced, the sequence of water entering the ejection duct and upper chamber is similar to Figure 1 but instead of air being vented through a vent hole it vents through the non return valve 18 and again water penetrates and fills the upper chamber via the pressure balance hole 9.

As regards the interruptible flush facility, this is identical in function to Figure 1.

An alternative arrangement of Figure 2 would consist of non return valve 18 being positioned at the base of siphon/ejection duct 16 or a combined siphon ejection duct and non return valve such that the bottom edge of the non return valve was marginally below the piston top 26. With this arrangement and the valve seated the upper chamber 11 would contain air so that on opening the valve (i.e. raising the piston 30) air would be displaced from the upper chamber via port 17, through the siphon/ejection duct and through the non return valve into the water.

Reseating of the valve would be different since air could only enter the upper chamber via the pressure balance hole 9, which would be larger than for Figure 2 to enable the piston to descend at an acceptable rate.

13 Refilling would again be similar to that of the valve depicted in Figure 2 except that the water level in the space between the piston and upper housing bore would only rise to a position level with the non return valve which would of course be slightly below the piston top 26, with the piston in the seated position.

Figure 3 shows a single flush valve in the fully opened position, which is functionally similar to Figure 1 except that an ejection duct 23 forming an integral part of the upper housing 8 is used instead of the separate ejection duct 16 of Figure 1. Moreover, since the lower edge of the ejection duct 23 is level with the housing flange 31, the piston in the fully raised position overlaps the upper end 24 of the ejection duct 23.

With the cistern filled and the valve seated, the upper chamber 11 contains water and there exists a free communication between the upper chamber and the surrounding cistern via ejection duct 23.

Operating the valve is achieved in the same way as before by the actuating device engaging with the lift collar 10 and raising the piston assembly 30 sufficiently for it to continue upwards to the top of the housing 8. With this valve, water is ejected from the upper chamber via the ejection duct 23 and this continues until the top of the piston 26 and the piston ring 7 approach the narrower upper end 24 of the ejection duct, where upon reaching this point the piston slows down due to throttling action imposed by the restricted path for the water being ejected during the final stages of the upward stroke. Water is ejected through the pressure balance hole 9 and vent 14 hole 35. This cushioning action occurs over the last 10 to 20% of the opening of the valve.

With the valve fully opened as shown in Figure 3, the cistern discharges through the outlet 1, 15 and the piston remains at the top of the upper housing until the buoyancy forces acting underneath the piston become less than the weight of the piston. At this stage the water level will have fallen below the lower flange 31 and air will penetrate the upper chamber via the pressure balance hole 9 and vent hole 35, followed by air entering duct 23. It is expected that the piston will reseat approximately one second after the cistern has emptied.

With the valve closed, i.e. main seal 5 seated on rim 33, refilling commences. The water level rises and when it reaches the lower flange 31 water enters the ejection duct 23 and flows into the upper chamber 11 displacing the air through the vent hole 35 which is in the upper housing wall higher than the upper end 24 of duct 23. Water continues to fill the upper chamber and thereafter the cistern until the set level 25 has been reached, i.e. the water inlet valve is closed by a float arm.

The arrangement according to Figure 3 has been described in relation to the upper chamber containing water and as such a collar of the same type as that used for Figures 1 and 2 could be flitted to provide an interruptible flush.

As an alternative to the valve shown in Figure 3 with water in the upper chamber, hole 35 could be eliminated. To enable adequate venting during the final stages of opening with the piston approaching the top of the upper housing, the pressure balance hole 9 could be made larger to relieve the cushion effect of the air compressed at the top of the housing. Also the height of the ejection duct could be increased to reduce the overlap between the runout of the upper end 24 of duct 23 and piston ring 7. With the upper chamber filled with air, there would be no provision for an interruptible flush. Generally only water filled upper chamber embodiments can be provided with interruptible flush, i.e. Figures 1 and 2.

It can be seen that all embodiments have a hollow stem 19 for providing an integral overflow, the function of which is self explanatory, although this has been described in the foregoing.

In all the embodiments of the invention as an alternative to the piston ring 7 and possibly to the pressure balance hole 9, the clearance between the bore of the upper housing and the plain cylindrical piston body could suffice provided that tolerances in manufacturing would enable the equivalent performance to be achieved.

Referring to Figure 4, the view again shows a cistern discharge/flush valve fitted at the bottom of a cistern 14 and immersed in water to a set level 25 and the valve closed with the main seal 5, scaling the raised seat rim 33 of outlet 1, 15 to prevent the ingress of water into the outlet. The upper chamber 11 is filled with air and is free to communicate with water in the cistern via the annular pocket or well 12, annular tapered channels/segments 48 (to be described below) and via a more restrictive passage, pressure balance aperture 42 (piston ring gap). Well 12 corresponds to annular pocket 12 of Figure 1 but tapers to a narrower bottom 53 from its wider upper end. Tapered channel 16 segments 48 are provided inside boss 28 which differs from the corresponding boss in Figure 1 in that in this embodiment the boss tapers inwardly to provide a wider opening 49 between the top of the boss and central stem 19, the opening proceeding via tapering channels 48 to a lower narrow throat 47 above annular opening 46. In the closed position the piston body 6 and hollow stem 19 assembly are kept in place (i.e. seated) by the weight of the said assembly and the pressure of the water on the piston top 26 and at the bottom 53 of the well 12.

The valve is opened by the operating device (either a pull up knob or lever) engaging with trunnion/yoke 44 to raise the main valve assembly 30 (piston 6, hollow stem 19), off the valve seat 33. At the point of opening the valve, the well 12 contains water and the level of water in the upper housing 8 is approximately level with the piston top 26. As the valve opens, the raising of the piston pushes initially water from the well 12 into the rounded opening 46 at the bottom of the boss 28 and into the narrow annulus (throat) 47. The water then flows through the tapered annular channels 48 and into an annular cup 50 defined by hollow boss 51 at the top of the housing. Soon after the flow of water from the well 12, air from the upper chamber 11 flows via the same passage upwards into the cup 50, where on emerging from the end 49 of the tapered channels, the air expands and erupts upwards through the water.

On opening the valve, as with the other embodiments, water from the cistem discharges through the apertures 3 1 B between supporting pillars 3 1 A and into the outlet 1, 15.

17 The tapering of the channel 48 enables the effort required to raise the piston to be reduced and the valve to open rapidly. Moreover the venturi ejector type action, once air is flowing from the upper chamber and the piston is raised sufficiently to provide a substantial upward force, will achieve a pressure at the rounded opening 46 less than the surrounding external water pressure due to head of water and thus the net upward force on the piston/hollow stem assembly 30 is marginally increased.

With the valve in the fully open position, i.e. the said assembly 30 at the top of the upper housing, sufficient water which was retained by the cup (annular well) 50 within boss 51 will have drained into the well 12 to form a labyrinth/trap seal. The valve will remain at the top of the upper housing during discharge and only when the level in the cistern has fallen to a level in the vicinity of the upper housing flange 3 1, will the weight of the said assembly be greater than the upward hydrostatic forces on the underside 4 of the piston. When this stage is reached the labyrinth seal comes into play and applies a slight vacuum in the upper chamber to keep the valve in the raised position. The only ingress initially is water at a very slow rate through the pressure balance aperture 42 (piston ring gap).

Once the water level has fallen below the flange 3 1, air then can vent, again at a slow rate, through the pressure balance aperture and into the upper chamber to cause the piston to descend at a rate slower than the rate at which the water level in the cistern is falling as it is approaching empty so that the cistern is empty before the piston has descended to the closed position (i.e. reseated with the main seal 5 on seat rim 33).

18 With the valve closed, refilling commences and the water level in the cistern rises. When the water level reaches the bottom of the upperhousing flange 31, air between the piston body 6 and the housing bore is pushed through the pressure balance aperture 42 into the upper chamber and into the tapered channel 48 and to atmosphere. As the level continues to rise water flows through the pressure balance aperture and into the upper chamber and into the well 12. Once the well 12 is filled, water then enters the rounded opening 46 and rises up the tapered channels 48 and onwards at the same level as the water in the surrounding cistern. The upper chamber forms an air lock and the air it contains is at a pressure equal to the pressure of water at the depth level with the piston top 26.

The water level continues to rise until the set level is reached and then the valve is ready for the next use.

Interrupting the flush to limit the amount of water discharged can be carried out at any part of the discharge by using the operating device to press down on the trunnion/yoke 44 which causes the piston/hollow stem assembly 30 to move downwards until the valve reseats i.e. main seal 5 seats on rim 33. If the interruption is made almost immediately after opening the valve, as the piston descends it would draw water into the upper chamber 11 via the annular and tapered channels/segments 48 and cup 50. If the level in the cistern falls below the slot 52 before the interruption is carried out, then mainly air is drawn into the upper chamber.

Following an interruption of the flow, with the valve reseated (closed) refilling takes place in the normal way as previously described except that the 19 amount of water required only being that to bring the cistern up to the set level 25.

The valve as with the other embodiments is provided with an integral overflow. If the water level in the cistern rises above the set level 25 - this being generally due to a leaking inlet valve - the maximum level is limited by the height of the hollow stem/overflow tube. Water reaches the top of the stem 34 and flows down the centre of the stem and into the outlet 1 and into the toilet pan.

There are a number of possible variations to Figure 4. For instance to enable the upper chamber 11 to fill with water, a port 17 and a non return valve 18, similar to those shown in Figure 2, could be incorporated in the top of the upper housing 8. The purpose of the non return valve would be solely for venting the upper chamber; discharging of the chamber during opening of the valve would of course still be substantially through the annular tapered channels 48.

Other possible variations would include parallel annular channels, instead of the tapered annular channels. At the top of the channels, a plate type non return valve could be fitted over the exit 49. For enabling a M150% air to water ratio or any other proportion, in the upper chamber 11, the boss 28 would contain a slot projecting up from its lower end so that on filling, the water level would rise above the piston top 26 until the upper end of the slot was reached.

Finally, to enable the upper chamber 11 to fill more quickly with water, a side pocket configurationally similar to the duct 23 of Figure 3, although much smaller, could be incorporated into the side wall of the upper housing 8. This pocket or slot could again extend upwards from the bottom flange 3 1, but would finish just beyond the outside rim of the piston body containing the piston ring 7 and thus on filling, both air and water would more readily flow via the slot into the upper chamber and thereby partially bypass the pressure balance aperture 42.

21 P. 1099 GB

Claims

1. A device for immersion in a fluid in a cistern (14), which comprises a housing (IA) having an upper portion (8) and a lower portion (31A), an upwardly movable main valve assembly (30) within the housing and forming therewith a variable volume upper chamber (11) and lower chamber (32A), a first vent means (9, 42) between the upper chamber (11) and the lower chamber (32A) and an outlet (15) leading down from lower housing portion (3 1 A), which portion (3 1 A) contains a seat (3 3) for the main valve assembly (30) at the entry (1) to the outlet (15) so that in the lowered position of the main valve assembly the outlet is blocked against the ingress of fluid in which the device is immersed, a central stem (19), extending upwardly from the main valve assembly (30) and actuable remotely from the upper housing (8) to raise the main valve assembly (30) of its seat, the wall of the lower portion (3 1 A) of the housing having apertures (3 1 B) above the seat (3 3), whereby on raising the main valve assembly immersion fluid can enter the outlet (15), the net upward buoyancy force acting on the assembly (30) thereby causing it to rise to the top of the upper chamber (11) and permit full flow of immersion fluid through the outlet and, on its substantially complete discharge, the cessation of flow allowing the main valve assembly to revert to its seated position, characterised in that a second vent means (17, 23, 47) is provided in the upper chamber (11) for ejection of fluid from the upper chamber by the rising main valve assembly (30) and in that air can penetrate into the upper chamber via the first and second vent means during descent of the main valve assembly, the upper housing portion (8) having a central hollow boss (28) 22 through which the central stem (19) extends and an annular pocket (12) being formed as a recess bound by a wall (12A) extending downwardly from the upper surface (26) of the main valve assembly and joined at its lower end to the stem (19), the boss (28) extending into this pocket which acts a water trap labyrinth.

2. A device according to Claim 1, characterised in that the first vent means is a pressure balance aperture (9) in a wall of the main valve assembly (30) adjacent its upper end.

3. A device according to Claim 1, characterised in that the first vent means is a gap (42) in a seal (7) between the main valve assembly (30) and the inner wall of the upper chamber (11).

4. A device according to Claim 1, 2 or 3, characterised in that the central stem (19) is hollow and extends above the normal full level (25) of fluid in the cistern (14).

5. A device according to any preceding claim, characterised in that the second vent means is a duct (16) extending downwardly from an outlet (17) adjacent the top of the upper chamber (1).

6. A device according to Claim 5, characterised in that the duct (16) has a vent hole (13) adjacent its upper end.

7. A device according to Claim 5, characterised in that the duct (16) has a non-return outlet valve (18) adjacent its upper end.

23

8. A device according to Claim 5, in which the duct (16) has a non-return valve (18) adjacent its lower end (27).

9. A device according to Claim 5, in which the duct (16) has a non-return valve (18) extending to just below the top (26) of the main valve assembly (30).

10. A device according to any one of Claims 1 to 4, characterised in that the second vent means is a duct (23) extending downwardly from a position a little below the top of the upper chamber (11) and defined between an integral outer wall of the upper housing (8) and the body (6) of the main valve assembly (30) in the raised position, the upper surface of the main valve assembly being above the uppermost entrance (24) to the duct in the fully raised position.

11. A device according to Claim 10, characterised in that upperTnost entrance (24) to the duct (23) is narrower than the remainder of the duct to provide a throttling effect.

12. A device according to any one of Claims 1 to 4, characterised in that the second vent means is upwardly through an annular passage (48) provided between the boss (28) and the central stem (19).

13. A device according to Claim 12, characterised in that the boss (28) tapers to provide a tapered annular passageway (48) which increases in crosssectional area from its lower end (47) to its upper end (49).

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14. A device according to Claim 13, characterised in that the 'lower end (47) of the tapered passageway leads to an opening (46) defined by a rounded lower edge of the boss (28).

15. A device according to Claim 12, 13 or 14, characterised in that the upper housing (11) has at its upper end a hollow boss (5 1) defining a well (50) communicating with the passageway (48).

16. A device according to Claim 15, in which a slot (52) is provided in the wall of the boss (5 1).

17. A device according to any one of Claims 11 to 16, characterised in that a non-return valve (18) is positioned in an outlet (17) adjacent the top of the upper chamber (11) to assist venting of the upper chamber.

18. A device according to any preceding claim, characterised in that it is provided with an interruptible flush facility.

19. A device according to Claim 1, substantially as hereinbefore described with reference to and as shown in Figure 1, 2, 3 or 4 of the accompanying drawings.