GB2575771A

GB2575771A - A Float Assembly For A Toilet

Info

Publication number: GB2575771A
Application number: GB1808145.5A
Authority: GB
Inventors: Craig Andrew
Original assignee: Fluidmaster GB Ltd
Current assignee: Fluidmaster GB Ltd
Priority date: 2018-05-18
Filing date: 2018-05-18
Publication date: 2020-01-29
Anticipated expiration: 2038-05-18
Also published as: GB2575771B; GB201808145D0

Abstract

The variable buoyancy float 56 has a main body 64 divided into at least two chambers 70, 74, wherein at least one of the chambers has a fluid inlet, preferably open base 69, for allowing fluid to enter the chamber and an air bleed vent 76, preferably spigot 80, for allowing air to exit the chamber as it fills with water. One chamber has a closed top providing a fixed volume of air and therefore a fixed buoyancy, while the buoyancy of the other chamber with the vent varies as water fills the cistern and the volume of air within the float varies. The float may be located within a shroud 48. The system aims to provide a delayed operation of a fill valve, and also to ensure full refilling of the cistern following a partial flush, due to the rate of water and air flowing into and out of the shroud and float during a flush cycle introducing delays into the cycle. The chamber may be located annularly around a central channel. Also claimed is an entire float assembly and fill valve including the variable float.

Description

A FLOAT ASSEMBLY FOR A TOILET

The present invention relates to a float assembly and in particular a float assembly for a toilet cistern fill valve.

A toilet cistern includes a fill valve arranged to supply water to fill the toilet cistern. The fill valve assembly requires a means of actuating the valve to open and close the valve and to control the flow of water into the cistern. Typically a fill valve assembly includes a float that is connected to the valve such that it closes the valve when the water level reaches a pre-defined maximum level, and opens the valve when the water level falls below this level to allow the flow to re-fill the cistern.

Traditional ballcock valves comprise a float attached via a lever arm to the fill valve, which controls in the incoming water supply. When the tank is empty the ballcock float is suspended at the end of the lever arm, which is pivoted downwardly. In position the fill valve is open and water enters the tank. When the water level reaches the ballcock float the float begins to rise with the water level until it eventually pivots the lever to a position where it closes the fill valve, which corresponds to a pre-set water level in the cistern. When the toilet is flushed, a flush valve is opened by the flush lever and water begins to pour out of the cistern into the toilet bowl. As soon as the float begins to fall the fill valve opens and water begins entering the cistern. This means that the toilet is emptying and filling at the same time. The rate that the water empties through the flush valve is greater than the rate of filling and the flush valve eventually closes. Nonetheless, a significant volume of the incoming water leaves the cistern in addition to the original flush volume and is wasted.

Delayed fill valves address this problem by only allowing a cistern to start refilling once the flush cycle has been completed. Delayed fill valves comprises a float chamber, otherwise referred to as a float shroud, within which the float is located. The float shroud includes a small inlet aperture in its base. As the cistern fills, the float shroud fills as water enters the shroud through the inlet aperture in the base or flowing into the upper end of the shroud. The float rises and closes the fill valve. When the toilet is flushed, the water leaves the cistern with a high flow rate. However, the size of the aperture in the base of the float shroud is significantly smaller in diameter than the flush outlet. As such, the flow rate from the shroud is far lower and the shroud takes longer to empty. As a result the water level in the shroud falls at a much slower rate than the water level in the cistern. The size of the aperture in the shroud is selected such that the float only falls to a level at which the fill valve opens once the flush volume has left the cistern and the cistern flush valve has closed.

As a further water saving measure, toilet cisterns are also provided with a 'dual flush' valve system. Dual flush valves allow a full flush, in which the full flush volume empties from the cistern, and a 'partial' flush, in which a reduced amount of water is emptied into the bowl. For example, dual flush valve assemblies are provided which use a siphon valve in which the siphoning action created in the siphon during flushing is used to control the volume of flushed water. During flushing the water falling through the cistern siphon draws water from within the cistern. The half flush setting on a dual flush valve interrupts the siphon effect by providing an air inlet aperture to the siphon that halts the siphon action once it is uncovered. The height of the aperture determines the volume of the 'half flush'. A dual flush valve can result in water savings of 2-3 liters per flush.

Problems have been experienced where delay flush valves and dual flush valves are used in combination. During a full flush, the water within the float shroud fully empties before the water level in the cistern rises again to the level of the shroud inlet aperture. However, during a 'half flush' cycle, the water level does not fall below the level of the inlet aperture and the float shroud does not fully empty. Therefore, when the cistern begins to refill the lag between the water level in the cistern rising and the water level in the shroud rising is less, and the float rises sooner. The height of the float is closer to the height of the water within the cistern. As a result the float rises to a height where it closes the fill valve before the water level in the cistern has reached the height required for a full flush volume. Consequently, when the user attempts to operate a full flush, the water volume is not sufficient and the user will often flush for a second time, which negates the intended water saving function of the delay fill and dual flush valves.

It is therefore desirable to provide an improved float assembly which addresses the above described problems and/or which offers improvements generally.

According to the present invention there is provided a float assembly as described in the accompanying claims. According to the present invention there is also provided a toilet cistern assembly as described in the accompanying claims.

In an embodiment of the invention there is provided a variable buoyancy float for a toilet fill valve assembly. The float comprises a main body having an upper end and a lower end; and hollow buoyancy chambers located within the main body comprising at least a first and a second hollow buoyancy chamber. The second hollow buoyancy chamber is a variable buoyancy chamber including a fluid inlet arranged to permit fluid to enter the variable buoyancy chamber and an aperture defining an air bleed vent arranged to allow air to exit the variable buoyancy chamber as the chamber fills with fluid entering through the fluid inlet.

Preferably the first hollow chamber is sealed at its upper end.

The fluid inlet of the variable buoyancy chamber may be arranged at its lower end and configured to permit the ingress and egress of fluid into and out of the variable buoyancy chamber.

Preferably the aperture defining the air bleed vent is located above the fluid inlet and arranged to allow air to exit the variable buoyancy chamber as fluid enters through the fluid inlet.

The first hollow chamber is preferably a constant buoyancy chamber that is retains the air contained within in use such that the amount of air therein is constant. The first hollow chamber is preferably configured such that air it is air tight when submerged in fluid.

The location of the air bleed vent above the fluid inlet allows the ingress of water from the within the flout shroud. As the height of the water in the chamber rises it forces the air within the chamber out the through the air bleed vent. If the air bleed vent was not present air would not be able to leave the chamber and as such the air pressure within the chamber would prevent water from entering. The ability of the variably buoyancy chamber to take in water reduces the overall volume of air within the float and therefore reduces the buoyancy of the float. The lower buoyancy float responds to a rising water level in the float shroud more slowly than a more buoyant float. As such, in a partial flush event where the water is not able to drain from the float, the float rises more slowly allowing more time for the cistern to re-fill to the desired level. At the same time, the constant buoyancy chamber ensures the some buoyancy is retained within the float.

The main body preferably includes a side wall and an upper wall. The two or more hollow chambers are open at their lower ends and closed at their upper ends by the upper wall which defines the rood of each chamber. The open lower end of the variable buoyancy chamber defines the fluid inlet and the air bleed vent comprises an aperture formed at the upper end of the variable buoyancy chamber in the upper wall.

The hollow chambers are preferably open only at their lower ends. The chambers are substantially tubular with a closed upper end. The air bleed aperture in the upper end of the variable buoyancy chamber is a pin-hole aperture, the size of which is specifically selected to determine the rate at which the chamber fills and empties with water.

The at least two hollow chambers are formed by one or more partition walls located within the main body, with the walls of the chambers comprising a portion of the side wall of the main body and at least a portion of at least one of the partition walls. Preferably the partition walls and main body are integrally moulded, with the main body, the hollow chambers, the partition walls and the air bleed vent being formed in a single moulding operation. As such the float is able to be more easily manufactured.

The main body preferably includes a vertical axis extending between the upper and lower ends and a tubular inner wall defining a central channel axially extending through the main body that is open at its upper and lower ends and is fluidly isolated from the two or more hollow chambers within the main body. The two or more hollow chambers are preferably arranged annularly around the central channel. The central channel allows the float to be located about the fill tube of a fill valve assembly is use with the fill tube acting as a vertical guide for the float.

The float preferably includes an axially extending channel formed in a side wall configured to axially receive and laterally retain a push rod actuator of a fill valve assembly. The channel includes a threaded portion configured to engage with a threaded surface on the push rod to vary the position of the float along the length of the push rod and is preferably integrally moulded with the float.

The variable buoyancy chamber has a cross sectional area, and the area of the air bleed vent aperture is preferably less than the cross sectional area of the variable buoyancy chamber. Preferably the air bleed vent aperture has a diameter of less than 2mm. More preferably the air bleed vent aperture has a diameter of less than 1mm, although the diameter ultimately depends on the buoyancy performance required of the float and any suitable diameter may be used.

In another aspect of the invention there is provide a float assembly for a toilet fill valve comprising a variable buoyancy flout as described above. A flout shroud is provided comprising a base and side walls defining a hollow enclosure within which the float is contained. A fill valve actuator is connected to the float;

The float shroud preferably includes a fluid aperture formed in the base arranged to permit fluid ingress and egress into and out of the chamber. The float and float shroud are arranged such the float is vertically movable within the float shroud to enable the float to rise and fall within the float shroud in response to a rise or fall of the water level within the float shroud, and the inlet aperture and air bleed aperture of the float are arranged such the variable buoyancy chamber fills with fluid as the fluid level within the float shroud rises. The float shroud is preferably includes an opening at its upper end.

The fill valve actuator comprises a rigid elongate member that is operatively connected to the valve such that vertical actuation of the actuator cooperates the valve.

The float is configured to travel within the float shroud in use between an uppermost position at which the valve actuator closes the fill valve and a lowermost position. The float is preferably spaced from the base of the float shroud at the lowermost position which allows water in the variable buoyancy chamber to fully drain into the float shroud to empty the variable buoyancy chamber of water when the water level in the float shroud is below the water inlet at the lower edge of the variable buoyancy chamber.

The valve actuator is preferably movable between an uppermost position in which it closes the valve and a lowermost position and the float is connected to the valve actuator such that the relative change in height of the float between its uppermost and lowermost positions is determined by the change in height of the valve actuator between its uppermost and lowermost positions. As the float is rigidly connected to the valve actuator, any change in height of the valve actuator causes a corresponding change in height of the float.

The position of the float along the length of the valve actuator is adjustable to vary the uppermost and lowermost positions of the float relative to the uppermost and lowermost positions of the valve actuator. In use this varies the height at which the float causes the valve actuator to close the valve, and therefore enable the maximum water level in the cistern to be set.

The main body of the float preferably includes a vertical axis extending between the upper and lower ends and a cylindrical or tubular inner wall defining a channel axially extending through the main body that is open at its upper and lower ends and is fluidly isolated from the two or more hollow chambers within the main body. The float shroud includes a cylindrical inner wall defining a tube axially extending through the float shroud that is open at its upper and lower ends, and the float is slidingly arranged around the tube of the float shroud with the tube extending through the central channel of the float. As such the filling tube is integrated with the float shroud, providing a compact arrangement that minimizes parts and materials.

The float assembly preferably further comprises a fill valve assembly having an outlet arranged to supply fluid to a toilet cistern. The fill valve outlet is arranged to supply fluid into the tube of the float shroud such that in use the tube of the float shroud functions as a filling tube channeling fluid into the toilet cistern from the fluid outlet of the valve assembly.

The present invention will now be described by way of example only with reference to the following illustrative figures in which:

Figure 1 shows a toilet cistern including a float assembly according to an embodiment of the invention; and

Figure 2 is shows a section view of a fill valve and float assembly according to an embodiment of the invention;

Figure 3 shows a toilet cistern including a fill valve and float assembly according to an embodiment of the invention with the cistern containing a full flush volume;

Figure 4 shows a section view of a fill valve and float assembly according to another embodiment of the invention;

Figure 5 shows a view from below of a float according to an embodiment of the invention; and

Figure 6 shows an isometric view of the float of Figure 5.

Referring to Figure 1, a toilet cistern assembly 1 comprises a cistern 2 having side walls 4 and a base 6 forming a liquid containing tank. A side entry inlet pipe 8 extends horizontally through the side wall 4 of the cistern 2, which is connected to the domestic water supply. The inlet pipe 8 has a threaded outer surface 10. Locking nuts 12 are provided on the threaded inlet pipe 8 on opposing sides of the side wall 4. A first locking nut 12a is located on the external side of the cistern side wall 4, and a second locking nut 12b is located on the internal side of the side wall 4. The locking nuts 12 are tightened in opposing axial directions to clamp against the side wall 2 and secure the inlet pipe 10 to the cistern 2. In an alternative embodiment described below the inlet pipe 8 may extend through the base 6 of the cistern 2.

A fill valve assembly 14 is connected to the inlet pipe 8 for controlling the flow of water from the inlet pipe 8 into the cistern 2. The fill valve assembly 14 comprises a valve 16, a valve actuator 18, and an outlet 20. The fill valve assembly further includes a float shroud 22 and a filling tube 24.

As shown in Figure 2, the valve 16 comprises a housing 26 having an inlet 28 connected to the inlet pipe 8. The housing 26 includes a main body 30 and a cap 32. The main body 30 includes a connector pipe 34 having the inlet 28 at one end, which connects to the inlet pipe 8. An inlet chamber 36 is located at the opposing end of the connector pipe 34 and is arranged vertically at 90 degrees to the connector pipe 34. The connector pipe 34 is in open connection with the inlet chamber 36 and enters the inlet chamber 36 proximate its base 38. An outlet connector 40 is located on the opposing side of the inlet chamber 36 to the connector pipe 34. The outlet connector 40 is not in open connection with the base of the inlet chamber 36, and is partitioned from the inlet chamber 36 by the side wall 42 of the inlet chamber 36. A diaphragm seal 44 is located at the upper end of the inlet chamber 36. The diaphragm 44 includes a sealing portion 46 that is configured and arranged to seat against the upper edge 48 of the inlet chamber to close the inlet chamber 36 and prevent fluid flow therethrough.

As shown in Figure 3, the float shroud 22 comprises an elongate hollow chamber having side walls 48 and a base 50. The chamber is open at its upper end 52. An aperture 54 is provided in the base 50 of the shroud 48 to allow fluid to enter the chamber of the float shroud 22, as indicated by arrow A. As such the interior of the float shroud 22 is in fluid communication with the body of water in the cistern 2 and the water level within the flout shroud 22 reaches an equilibrium with the water level in the tank. A float 56 is housed within the float shroud 22. The float 56 and the float shroud 22 are configured such that the float 56 is received within the float shroud 22 with a close sliding fit. The float 56 is configured to slide axially in the vertical direction within the float shroud 22, with the side walls 48 of the float shroud 22 acting as a guide for the float 56.

The float 56 is connected to the vertical push rod 58 which forms part of the valve actuating assembly 18. The float 56 is formed of a moulded plastic and includes a threaded channel or a channel including at least a threaded portion that is integrally moulded into a side edge of the float 56. The channel receives the threaded push rod 58 and the threaded engagement between the threaded portion of the channel and the push rod 58 fixes the float 56 to the push rod 58. Rotation of the threaded push rod 58 relative to the float 56 enables the height of the float 56 along the length of the push rod 58 to be adjusted, to vary the height at which the float causes the push rod 58 to close the valve 14, an hence vary the full flush volume of the cistern.

At its upper end the push rod 58 is connected to a linkage 60. The linkage 60 is arranged such that upwards movement of the push rod 58 causes an actuating portion of the linkage 60 to pivot downwardly. This causes the sealing portion 46 of the diaphragm 44 to move into sealing engagement with the upper end of the inlet chamber 36, which closes the inlet chamber 36 and prevents flow to the outlet 20. Conversely, movement of the push rod 58 in the downward direction pulls the linkage 60 downwards and causes the diaphragm 44 to move out of sealing engagement with the inlet chamber 36 and allows flow to the outlet 20.

The float 56 includes a main body 64 having side walls 66 and an upper wall 68. The float 56 is open at its base 69. A plurality of chambers 70 are formed within the body 64 of the float 56 which are defined by partition walls 72 within the main body 64. The chambers 70 are open at the base end 69 and closed at the upper end by the upper wall 68. Therefore, the air pressure within the chambers 70 prevents water from entering the chambers 70 and maintains the buoyancy of the float 60. One of the chambers 74 is provided with an aperture 76 formed in the upper wall 68 which defines an air bleed aperture 78 allowing air to enter and exit the chamber 74. The air bleed aperture 78 includes a spigot 80 formed on and extending upwardly from the upper wall 68 having the aperture 76 extending therethrough. The presence of the air bleed aperture 78 in the chamber 74 means that air is able to exit the chamber 74, which allows water to enter the chamber 74 during filling while the remaining chambers 70 remain filled with air.

Figure 4 shows an arrangement in which the cistern 2 is filled to the full flush volume and the water inlet has been closed by the valve 14. The float shroud 22 has filled with water to the same level as the water level within the cistern. The chamber 70 contains no water due to the air pressure within the chamber 70 and the fact that the chamber 70 is closed at its upper end. The chamber 74 has filled with water up to the same level as the float shroud 22 and the cistern 2. This occurs as the water level in the float shroud 22 rises and water reaches the base 69 of the chamber 74 and begins to enter the chamber 74 and force the air within the chamber 74 out through the air bleed aperture 78. Due to the size of the aperture 76 there is a lag between the water level in the chamber 74 and the water level in the shroud 22, but the two levels eventually equilibrate. The volume of air evacuated from the chamber 74 reduces the overall volume of the air within the float 56. Consequently the buoyancy of the float 56 decreases.

During a partial flush operation the water level in the cistern falls, as does the water level in the shroud 22. At its lowest level the water level remains above the lower edge 69 of the float 56. In addition, the size of the aperture 76 limits the rate at which air is able to re-enter the chamber 74 as the water level in the shroud 22 and cistern falls. As such, a lag is introduced between the rate at which the water level in the cistern 2 falls and the rate at which the water level in the chamber 74 is able to fall, with the majority of the water being retained with the chamber 74 during the time the partial flush volume takes to exit the cistern. Therefore, due to the water remaining within the chamber 74, the buoyancy of the float 56 continues to be reduced. Consequently, as the cistern 2 begins to refill and the water level within the shroud 22 rises, the reduced buoyancy of the float 56 means it does not rise as quickly as when fully buoyant. This introduces a lag between the rising water level in the cistern 2 and the height of the float 56. As the float 56 does not rise as quickly as when fully buoyant, the water level in the cistern is able to reach the full flush volume before the float 56 rises to the level where it closes the valve 14.

When the full flush operation is selected, the water level in the cistern falls to a level below the lower edge 50 of the float shroud 22 and below the lower edge 69 of the float 56. Once the water level falls below the lower edge 69 of the float 56 the water in the chamber 74 begins to drain out. The rate at which the water drains is limited by the flow of air into the aperture 76 but the period between the water level falling below the lower edge 69 of the float and then rising to this level again during filling is more than sufficient for the chamber 74 to empty fully. The float shroud 22 also empties fully in this period. Therefore, as the water level reaches the level of the aperture 54 in the shroud 22 the shroud 22 begins to fill with normal lag behind the cistern level. When the water level in the shroud 22 reaches the float 56 the float 56 is fully buoyant and rises at the quicker rate accordingly. Although some water may enter the chamber 74 as the float 56 rises the float 56 remains substantially fully buoyant as it rises to the valve shut off position. Once the float 56 reaches this position and stops rising the water level continues to rise within the chamber 74 due to the lag cause by the small diameter of the aperture 76. The chamber 74 fills to the same level as the shroud 22 and cistern 56 and the float 56 is then ready to accommodate a full or partial-flush and return the water level to the same full-flush volume which ever flush operation is selected.

In an alternative embodiment shown in Figure 5 the float 156, includes a main body 164 having an outer side wall 166, an upper wall 168 and an inner wall 171. The float 156 is open at its base 169. The inner wall 171 defines a central channel 173 extending axially through the float 156 that is open at both ends. The central channel 173 is configured to receive the fill tube 124 to locate the float 156 around the fill tube 124. A plurality of chambers 170 are formed within the body 164 of the float 156 which are defined by partition walls 172 which segregate the internal volume of the main body 164. The chambers 170 are open at the base end 169 and closed at the upper end by the upper wall 168.

The float 156 includes a channel 180 integrally moulded into the side wall 164. The channel 180 is substantially circular in cross section and has an open channel 182 extending along its outer edge 184 configured such that the channel 180 is substantially C-shaped. A threaded portion 186 is located at the upper edge of the channel 180. The channel 180 is configured to axially receive the push rod 158, which threading engages with the threaded portion 186. The c-shape of the channel allows it to extend around a substantial portion of the circumference of the push rod 158, and more than 180 degrees, which enables it to retain the push rob within the channel 180which acts as a guide. A concave scalloped channel 190 extends axially along the length of the opposing side. The float shroud 122 includes a corresponding convex axially extending internal ridge and the ridge and the scalloped section 190 cooperate to guide the float during axial movement within the shroud 122.

The buoyancy variation chamber 174 is provided with an aperture 176 formed in the upper wall 168 which defines an air bleed aperture 178 allowing air to enter and exit the chamber 174. As shown in Figure 6 the air bleed aperture 178 includes a spigot 180 formed on and extending upwardly from the upper wall 168 having the aperture 176 extending therethrough.

As shown in Figure 4, the float shroud 122 has an inner axially extending central wall 192 which is tubular in shape. The tube shaped cylindrical wall 192 is open at its lower end and at its upper end is also open and stops short of the upper edge 152 of the outer wall 156 of the shroud 122. The central tube 192 forms the main body of the filling tube 124. The filling tube 124 is therefore integrally formed with the float shroud 122. The float shroud 122 includes an annular base 150 surrounding the outlet of the filing tube 124. An enlarged diameter upper filling section 182 is secured to the upper end of the central tube 192. The enlarged diameter filing section 182 has vertical side walls and a tapered lower section tapering to the diameter of the tube 192. The enlarged diameter filing section 182 functions as a funnel providing an enlarged opening to the filling tube 124 and channeling liquid into the filling central tube 192.

The main central tube body 192 of the filling tube 124 extends through the central channel 173 of the float 156 such that the float is located radially outwards of the tube body 192, extending around the circumference thereof with a substantially toroidal form. The tube body 192 therefore acts as a guide for the float 156 which slides up and down about the central tube 192 within the float shroud 122.

Claims

1. A variable buoyancy float for a toilet fill valve assembly, the float comprising:

a main body having an upper end and a lower end; and two or more hollow buoyancy chambers located within the main body comprising at least a first and a second hollow buoyancy chamber;

wherein the second hollow buoyancy chamber is a variable buoyancy chamber including a fluid inlet arranged to permit fluid to enter the variable buoyancy chamber and an aperture defining an air bleed vent arranged to allow air to exit the variable buoyancy chamber as the chamber fills with fluid entering through the fluid inlet.

2. A variable buoyancy float according to claim 1 wherein the air inlet of the variable buoyancy float is located at the lower end of the chamber and the air bleed vent is located above the fluid inlet.

3. A variable buoyancy float according to claim 1 or 2 wherein the main body includes a side wall and upper wall and the two or more hollow chambers are open at their lower ends and closed at their upper ends by the upper wall, the open lower end of the variable buoyancy chamber defines the fluid inlet.

4. A variable buoyancy float according to claim 3 wherein the air bleed vent comprises an aperture formed in the upper wall within the variable buoyancy chamber.

5. A variable buoyancy float according to claim 3 or 4 wherein the at least two hollow chambers are formed by one or more partition walls located within the main body.

6. A variable buoyancy float according to claim 5 wherein the partition walls and main body are integrally moulded.

7. A variable buoyancy float according to any preceding claim wherein the main body includes a vertical axis extending between the upper and lower ends and a cylindrical inner wall defining a central channel axially extending through the main body that is open at its upper and lower ends and is fluidly isolated from the two or more hollow chambers within the main body.

8. A variable buoyancy float according to claim 7 wherein the two or more hollow chambers are arranged annularly around the central channel.

9. A variable buoyancy floaty according to claim 8 wherein the float includes an axially extending channel formed in a side wall configured to axially receive and laterally retain a push rod actuator of a fill valve assembly.

10. A variable buoyancy floaty according to claim 9 wherein the channel includes a threaded portion configured to engage with a threaded surface on the push rod to vary the position of the float along the length of the push rod.

11. A variable buoyancy float according to any preceding claim wherein the variable buoyancy chamber has a cross sectional area, and the area of the air bleed vent aperture is less than the cross sectional area of the variable buoyancy chamber.

12. A variable buoyancy float according to claim 11 wherein the air bleed vent aperture has a diameter of less 2mm.

13. A variable buoyancy float according to claim 11 wherein the air bleed vent aperture has a diameter of less than 1mm.

14. A variable buoyancy float according to any preceding claim wherein the at least first one hollow chamber is configured such that the chamber is air tight when the chamber is submerged in fluid.

15. A float assembly for a toilet fill valve comprising:

a variable buoyancy flout according to any preceding claim;

a flout shroud comprising a base and side walls defining a hollow enclosure within which the float is contained;

a fill valve actuator connected to the float;

wherein the float shroud includes a fluid aperture formed in the base arranged to permit fluid ingress and egress into and out of the chamber and the float and float shroud are arranged such the float is vertically movable within the float shroud to enable the float to rise and fall within the float shroud in response to a rise or fall of the water level within the float shroud, and the inlet aperture of the variable buoyancy chamber of the float is arranged such the variable buoyancy chamber fills with fluid as the fluid level within the float shroud rises.

16. A float assembly according to claim 15 wherein the float is configured to travel within the float shroud in use between an uppermost position at which the valve actuator closes the fill valve and a lowermost position in which the float is spaced from the base of the float shroud to allow fluid in the variable buoyancy chamber to drain into the float shroud when the fluid level in the float shroud is below the fluid inlet at the lower edge of the variable buoyancy chamber.

17. A float assembly according to claim 16 wherein the valve actuator is movable between an uppermost position in which it closes the valve and a lowermost position and the float is connected to the valve actuator such that the relative change in height of the float between its uppermost and lowermost positions is controlled by the change in height of the valve actuator between its uppermost and lowermost positions.

18. A float assembly according to claim 17 wherein the position of the float along the length of the valve actuator is adjustable to vary the uppermost and lowermost positions of the float relative to the uppermost and lowermost positions of the valve actuator.

19. A float assembly according to claim 18 wherein the main body of the float includes a vertical axis extending between the upper and lower ends and a cylindrical inner wall

5 defining a channel axially extending through the main body that is open at its upper and lower ends and is fluidly isolated from the two or more hollow chambers within the main body, and the float shroud includes a cylindrical inner wall defining a tube axially extending through the float shroud that is open at its upper and lower ends, and the float is slidingly arranged around the tube of the float shroud with the tube extending through 10 the central channel of the float.

20. A float assembly according to claim 19 further comprising a fill valve assembly having an outlet arranged to supply fluid to a toilet cistern, wherein the fill valve outlet is arranged to supply fluid into the tube of the float shroud such that in use the tube of the float shroud functions as a filling tube channeling fluid into the toilet cistern from the fluid 15 outlet of the valve assembly.