AU2006201060A1 - Cistern Regulation - Google Patents

Description

Cistern Regulation Field of Invention The present invention relates to cisterns (or flush tanks as the devices are known in the USA) and, in particular, to cisterns having a flush valve.

Background Art Cisterns can be categorized into two categories. The first are cisterns having a flush valve in the base thereof. The second are syphonic cisterns incorporating an inverted U-tube to interconnect the cistern with the toilet pan or bowl. This U-tube is normally empty and must be filled with water in order to initiate a flush. As a consequence, syphonic cisterns are inherently non-leaking.

However, cisterns of the first category are able to leak substantial volumes of water in the event that the flush valve operates less than perfectly. For example, an imperceptible leak of say, 1 millilitre per minute can result in the loss of approximately 1 litres in 24 hours.

In order to overcome this problem, various proposals gave been made. US Patents 4,843,657 (Orr), 4,965,891 (Antunez) and 5,742,951 (Wright-Caroma Industries) disclose a mechanical latch system to prevent the inlet valve refilling the cistern unless the flush actuator has been operated to initiate a flush. Thus the maximum water loss due to a leaking flush valve is limited to only the entire contents of the full cistern.

US Patent 5,287,882 (Mikel-Moen Corp) discloses the use of a combined float and weight to prevent refilling of a leaking cistern. The weight is formed by water which drains away slowly, thereby changing the buoyant force of the combined float and weight which floats in the general body of water within the cistern. A linkage interconnects the combined float and weight with the inlet valve. A slow leak results in the combined float and weight having insufficient weight to open the inlet valve.

Thus, again, only the contents of a single full cistern are wasted in the event of a leak.

5021B-AU US Patent 5,211,204 (Mikol-Moen Inc.) discloses the arrangement of 5,287,882 plus a mechanical latch in the form of arm 32 which retains the inlet valve control float 24 raised until the flush initiating mechanism is actuated.

US Patent No. 4,901,377 (Weir) discloses a mechanical arrangement which prevents loss of water in the event of catastrophic failure of the flush valve. A bellows arrangement senses that the cistern is substantially empty for a lengthy period of time and then exerts an upwards pressure on the inlet valve float so that the float and float arm rise to reduce the flow through the inlet valve. In a variation, a string tensioned into a U-shaped path is designed to lift the inlet valve float arm after the cistern has been empty for a period.

British Patent Application GB 2,162,874A discloses another arrangement in which a cylindrical inner tank with an open top is rotated within a cistern in order to initiate a flush. Once empty the inner tank is rotated back to its initial position for re-filling.

Such a cistern does not have a flush valve and therefore cannot lose water via a faulty flush valve.

To the applicant's knowledge, none of the above proposals have been used commercially.

In addition to the problem of possible loss of water, in most jurisdictions it is a requirement that the outlet of the cistern inlet valve always be above the level of water within the cistern. This requirement prevents the possibility that a transient negative pressure in the water mains connected to the inlet of the cistern's inlet valve, results in water from the cistern inadvertently re-entering the mains supply and thereby possibly contaminating that mains supply. As a consequence, the outlet of the inlet valve is above the overflow level of the cistern which is, in turn, above the intended maximum water level for the cistern.

In order to meet this requirement, it is desirable to be able to accurately set the maximum water level of the cistern. For many inlet valves, and particularly those not having a toggle-like action, this can be difficult. Especially for conventional ball cock 5021B-AU valves having a pivoted long float arm to the free end of which a float is attached, setting the maximum water level can be fraught with problems.

A typical scenario is that during the late night/early morning, water supply reservoirs are replenished, thus raising their water level and thereby increasing mains pressure.

As a consequence, many inlet valves admit water progressively into a cistern until the cistern water level has risen to provide a counter-acting float arm force which again closes the inlet valve. Often this scenario results in water rising during the night to the overflow level and thus being drained away, either into the bowl of the toilet pan or onto the floor of the bathroom. In either case, a loss of water each night is possible.

The present invention has its genesis in a realization that control of water loss can best be achieved by control of the inlet valve. In particular, instead of attempting to hold the inlet valve closed by means of a mechanical latch as in the abovementioned prior art, the present invention utilizes an auxiliary tank in which the water level can be closely controlled and in which is upwardly buoyed the normal float arrangement which opens and closes the inlet valve.

Summary of the Invention In accordance with a first aspect of the present invention there is disclosed a method of regulating a cistern having a main flush valve and an inlet valve which is opened and closed by motion of a float in response to a falling and a rising level respectively of water in the cistern, said method comprising the steps of: providing an auxiliary tank for said float, (ii) introducing water via said inlet valve into said cistern but not into said auxiliary tank, (iii) allowing water above a predetermined height in said cistern to flow into said auxiliary tank, (iv) providing said auxiliary tank with an auxiliary flush valve to drain said auxiliary tank into said cistern, opening said auxiliary flush valve when said main flush valve is opened, and (vi) closing said auxiliary flush valve in response to a dropping water level in said auxiliary tank.

5021B-AU In accordance with a second aspect of the present invention there is disclosed a cistern having a main flush valve and an inlet valve which is opened and closed by falling and rising respectively of a float, wherein said cistern includes an auxiliary tank which houses said float and includes an auxiliary flush valve which drains said auxiliary tank into said cistern, said inlet introduces water into said cistern but not into said auxiliary tank, said auxiliary tank is supplied with water by water reaching a predetermined height within said cistern, at least one flush actuator which opens both said main flush valve and said auxiliary flush valve, and closing means to close said auxiliary flush valve in response to a dropping water level in said auxiliary tank.

Brief Description of the Drawings A preferred embodiment of the present invention will now be described with reference to the drawings in which: Fig. 1 is a schematic transverse vertical cross-sectional view through a cistern incorporating the arrangements of the preferred embodiment, Fig. 2 is a similar view of a part only of the cistern of Fig. 1 showing the inlet valve and flush actuation arrangement prior to a flush being actuated, Fig. 3 is a view similar to Fig. 2 but showing the position after initiation of a flush, and Fig. 4 is a view similar to Figs 2 and 3 but showing the position at the conclusion of the flush.

Detailed Description As seen in Fig. 1, a cistern 1 has a base 2 and sidewalls 3. A spigot 4 which connects to a flush pipe and thence to a toilet bowl (both not illustrated) extends from the base 2. A main flush valve 5 is atop the spigot 4. Located above the main flush valve 5 is a flush valve lifting mechanism 7 which incorporates an overflow pipe (not illustrated but conventional) thereby setting an overflow level 8.

Also located within the cistern 1 is an inlet tube 10 atop of which is located an inlet valve 11. Thus far the components are substantially conventional and substantially as illustrated in the present applicant's abovementioned US Patent No. 5,742,951.

Pivoted to the inlet valve 11 is a float arm 12, the free end 13 of which abuts a float 14. An auxiliary tank 16 which is secured to the inlet tube 10 houses the float 14.

5021B-AU The auxiliary tank 16 has an open top having a lower lip 17 which (as will be explained hereafter) sets a maximum water level 18 for the cistern. This is well below the height 19 of the outlet of the inlet valve 11.

The float 14 can be provided with one or more chambers which can be closed (ie air and water tight), drainable (ie able to be filled with water and then slowly drained), an inverted cup (and thus only buoyant after water has occluded the downwardly facing opening) or a bucket (and thus be fillable with water). By means of combining such features, the buoyant force and/or weight of the float 14 under various circumstances can be adjusted as desired.

As best seen in Fig. 3, adjacent the base 26 of the auxiliary tank 16, and preferably let into the base 26 itself, is an auxiliary flush valve 25 which is provided with a sealing O-ring 22. The auxiliary flush valve 25 is also provided with an over-centre toggle spring 23 fabricated from stainless steel.

Located below the auxiliary flush valve 25 is an actuating lever 27 which is pivoted at one end 28 to the inlet tube 10. The actuating lever 27 is connected at its free end 29 via a linkage 31 to a flush lever 32 pivotally mounted on the flush valve lifting mechanism 7. The flush lever 32 is able to be pivoted anti-clockwise as seen in Fig. 3 by pressing of either one of the flush actuators 6 (one for low volume flush and one for high volume flush respectively), thereby pivoting the actuating level 27 clockwise about its pivot 28. The linkage 31 interconnecting the actuating lever 27 and flush lever 32 can be a flexible chain or cable, or a rod with a pivot at each end, or similar.

Any arrangement which results in the actuating lever 27 being pivoted in a clockwise direction when either one (or both) of the flush actuators 6 are depressed, will suffice.

In operation, the situation prior to a flush is illustrated in Fig. 2. The cistern 1 has water filled to the maximum water level 18 and the auxiliary tank 16 is filled to its operational depth 36 at which height the float arm 12, being substantially horizontal, has closed the inlet valve 11.

When either one of the flush actuators 6 is pressed, as illustrated in Fig. 3, the flush valve lifting mechanism 7 lifts the main flush valve 5 to initiate the flush. At the 5021lB-AU same time the actuating lever 27 pivots clockwise to open the auxiliary flush valve The toggle spring 23 maintains the auxiliary flush valve 25 open. Thus, as water flows from the cistern 1 through the main flush valve 5, so too does water flow from the auxiliary tank 16 through auxiliary flush valve 25, in order to contribute to the flushing volume.

As seen in Fig. 4, this naturally lowers the level 36 of water within the auxiliary tank 16. Eventually, the descending float 14 hits the top of the auxiliary flush valve with sufficient force to overcome the action of toggle spring 23 and thereby close the auxiliary flush valve 25. Meanwhile, the anticlockwise motion of the float arm 12 opens the inlet valve 11 thereby causing the cistern 1 (but not the auxiliary tank 16) to begin refilling. This is the situation illustrated in Fig. 4.

The cistern 1 continues refilling with the inlet valve 11 open to a maximum extent until the water level in the cistern I reaches the height of the lip 17. Then water cascades over the lip 17 in order to commence filling the auxiliary tank 16. As the water in the auxiliary tank 16 approaches the operational depth 36 illustrated in Fig. 2, the inlet valve 10 is quickly progressively closed. In this way, the cistern 1 (but not the tank 16) has been refilled to the desired maximum water level 18.

A number of important consequences flow from the above operation. Firstly, in the event of the main flush valve 5 leaking, there is no prolonged leak and only the water having access to the main flush valve 5 can leak away. In particular, the water within the auxiliary tank 16 will not be lost because the auxiliary flush valve 25 is unlikely to also leak.

A more important consequence of the above described operation concerns the improved operation of the inlet valve 11. Firstly, when the auxiliary tank 16 drains with the main flush valve 5 open, the auxiliary flush valve 25 is almost immediately thereafter closed by the float 14, so little or no water enters the auxiliary tank 16 via the auxiliary flush valve 25. Thus the inlet valve 11 opens, and remains wide open until the water in the cistern 1 reaches the maximum water level 18. Only thereafter is the inlet valve 11 reduced from its maximum open position as the tank 16 begins to fill. The consequence of this is that the cistern 1 refills quickly. This advantage is 5021lB-AU maximised by making the volume of the auxiliary tank 16 small relative to the remainder of the cistern 1.

Secondly, the inlet valve 11 will close when the water in the auxiliary tank 16 reaches the operational depth 36 indicated in Fig. 2. Should the inlet pressure now rise at night (as explained above), although more water may be let into the cistern 1 via the inlet valve 11, this water flows over the lip 17 and so does not increase the depth of water in the cistern 1. Instead, the operational depth 36 rises slightly and the inlet valve 11 is more firmly urged closed. Most importantly, no water is lost via the overflow pipe included in the flush valve lifting mechanism 7.

As a consequence of the above described operation, the maximum water level 18 can be accurately set by selecting the height of the lip 17 of the auxiliary tank 16 which is secured to the inlet tube. This selection can be made by adjusting the position of the tank 16 on the inlet pipe 10, or by changing the height of the lip 17 relative to the base 26 of the tank 16.

A significant advantage is achieved by controlling the inlet valve using the water level in the auxiliary tank. In particular, the upwards buoyant force exerted by the float 14 is much larger than that able to be generated by a mechanical latch. The latch arrangement involves a lever being lifted to, or above, a predetermined latch setting level by refilling of the cistern level. Thereafter the lever is merely held up at that level as the water in the cistern drains away. By keeping the float 14 buoyed by the level of water in the auxiliary tank 16, the maximum upwards (and thus closing) force is applied to the inlet valve.

Of course it is also possible for the auxiliary flush valve 25 to leak. However, this is unlikely for two reasons. Firstly, the grit and miscellaneous debris inevitably introduced into the cistern 1 via the mains supply and inlet valve 11, are not introduced into the auxiliary tank 16. Therefore leaking of the auxiliary valve 25 due to such grit or debris is impossible. Secondly, the auxiliary flush valve 25 is subject to different design constraints than those to which the main flush valve 5 is subject (for example, the valve 25 can be in the vertical side wall of the auxiliary tank 16 adjacent the base thereof, can be provided with a toggle spring 23, etc.).

5021B-AU Further, if the auxiliary flush valve 25 should happen to leak and the main flush valve not leak, then water will enter the auxiliary tank 16 via the valve 25. As a consequence, the water level 36 in the auxiliary tank 16 will rise and the float 14 will be submerged to a greater extent, but no more water will enter the cistern 1 via the inlet valve 11, nor will any water be lost via the main flush valve 5. So no harm is caused by this condition.

The foregoing describes only one embodiment of the present invention and modifications, obvious to those skilled in the sanitary ware arts, can be made thereto without departing from the scope of the present invention.

The term "comprising" (and its grammatical variations) as used herein is used in the inclusive sense of "including" or "having" and not in the exclusive sense of "consisting only of'.

5021B-AU

Claims (11)

1. A method of regulating a cistern having a main flush valve and an inlet valve which is opened and closed by motion of a float in response to a falling and a rising level respectively of water in the cistern, said method comprising the steps of: providing an auxiliary tank for said float, (ii) introducing water via said inlet valve into said cistern but not into said auxiliary tank, (iii) allowing water above a predetermined height in said cistern to flow into said auxiliary tank, (iv) providing said auxiliary tank with an auxiliary flush valve to drain said auxiliary tank into said cistern, opening said auxiliary flush valve when said main flush valve is opened, and (vi) closing said auxiliary flush valve in response to a dropping water level in said auxiliary tank.

2. The method as claimed in claim 1 including the further step of: (vii) using contact between said float and said auxiliary valve to close said auxiliary flush valve in step (vi).

3. The method as claimed in claim 1 or 2 including the further step of: (viii) providing a linkage between said auxiliary flush valve and at least one actuator for said main flush valve to thereby substantially simultaneously open both said flush valves when carrying out step

4. The method as claimed in any one of claims 1-3 including the further step of: (ix) setting a rim of said auxiliary tank at said predetermined height in carrying out step (iii). The method as claimed in any one of claims 1-4 including the further step of: locating said auxiliary tank within said cistern adjacent said inlet.

6. A cistern having a main flush valve and an inlet valve which is opened and closed by falling and rising respectively of a float, wherein said cistern includes an auxiliary tank which houses said float and includes an auxiliary flush valve which drains said auxiliary tank into said cistern, said inlet introduces water into said cistern but not into said auxiliary tank, said auxiliary tank is supplied with water by water reaching a predetermined height within 5021B-AU said cistern, at least one flush actuator which opens both said main flush valve and said auxiliary flush valve, and closing means to close said auxiliary flush valve in response to a dropping water level in said auxiliary tank.

7. The cistern as claimed in claim 6 wherein said closing means comprises said float coming into contact with said auxiliary flush valve.

8. The cistern as claimed in claim 6 or 7 wherein said flush actuator(s) include a linkage to said auxiliary flush valve whereby said main flush valve and said auxiliary flush valve are opened substantially simultaneously.

9. The cistern as claimed in any one of claims 6-8 wherein said auxiliary tank is supplied with water via a rim thereof and said rim is set at said predetermined height. The cistern as claimed in any one of claims 6-9 wherein said auxiliary tank is located within said cistern.

11. The cistern as claimed in claim 10 wherein said auxiliary tank is adjacent said inlet.

12. A cistern substantially as herein described with reference to the drawings.

13. A method of regulating a cistern, said method being substantially as herein described with reference to the drawings. Dated this 14 th day of March 2006 CAROMA INDUSTRIES LIMITED By FRASER OLD SOHN Patent Attorneys for the Applicant 5021B-AU