dual flush valve

Abstract

A dual flush valve ( 1 ) comprises a housing ( 10 ) having an outlet ( 2, 36 ) and a main valve assembly ( 34 ) movable within the housing between a raised position in which the valve is open and a lowered position in which the valve is closed. An operating system ( 14 ) is actable in response to an input to raise the main valve assembly ( 34 ) off its seat ( 2 A) so that it is subjected to an upwards force by immersion fluid entering the outlet. In response to a first actuation input, the operating system exerts a first downward force on the main valve assembly ( 34 ) so that the main valve assembly is caused to descend when the fluid in the cistern reaches a first predetermined intermediate fluid level ( 31 ) to provide a partial flush. In response to a second actuation input the operating system exerts a second downward force on the main valve assembly ( 34 ) which is lower than the first downward force so that main valve assembly is caused to descend when the fluid in the cistern reaches a second predetermined intermediate fluid level ( 32 ) lower than the first intermediate fluid level to provide a full flush.

1 . A dual flush valve for immersion in a fluid in a cistern, the valve comprising: a main valve assembly, an outlet having a valve seat for the main valve assembly, a guide structure for positioning and guiding the main valve assembly relative to the outlet for movement between a lowered position in which the main valve assembly locates on the valve seat to seal the outlet to prevent immersion fluid flowing from the cistern through the outlet and a raised position in which the outlet is not sealed; an operating system actuable in response to an input to raise the main valve assembly off its seat so that on raising the main valve assembly the main valve assembly is subjected to an upwards force by immersion fluid entering the outlet, thereby causing it to rise to permit full flow of immersion fluid through the outlet, the operating system having a mechanism for subsequently exerting a downward force on the main valve assembly sufficient to exceed any buoyancy force and fluid level dependent flow reaction and pressure forces acting upwards on the main valve assembly so that the main valve assembly descends and reverts to its lowered seated position when the fluid in the cistern reaches a pre- determined level; characterised in that the operating system is operative in response to a first actuation input to exert a first downward force on the main valve assembly so that the main valve assembly is caused to descend and revert to its lowered, seated position when the fluid in the cistern reaches a first predetermined intermediate fluid level and is operative in response to a second actuation input to exert a second downward force on the main valve assembly which is lower than the first downward force so that the main valve assembly is caused to descend and revert to its lowered, seated position when the fluid in the cistern reaches a second predetermined intermediate fluid level lower than the first intermediate fluid level. 
     
     
         2 . A dual flush valve as claimed in  claim 1 , in which the guide structure comprises a housing within which the main valve assembly is movable between lowered and raised positions, the housing having a lower housing portion in which the valve seat is provided, a wall of the lower housing portion having openings through which immersion fluid can flow to the outlet when the main valve assembly is raised off the valve seat. 
     
     
         3 . A dual flush valve as claimed in  claim 2 , in which the a housing has an upper portion separated from the lower portion by a partition plate to define upper and lower chambers, the valve including a first vent means through which fluid may pass between the upper and lower chambers, a second vent means within the upper chamber between the main valve assembly and a wall of the upper housing portion through which fluid may flow from one end of the upper chamber to the other, a third vent means towards the upper end of the upper housing portion through which immersion fluid can flow between the upper chamber and the surrounding cistern, the main valve assembly including a central stem which projects upwardly beyond the upper end of the housing for co-operation with the operating system. 
     
     
         4 . A dual flush valve as claimed in  claim 1 , in which the first and second downward forces exerted by the operating system are applied to the main valve assembly by direct means, e.g. a catch mechanism or a latching device engaging with a detent, e.g. a flange or similar feature on the raised main valve assembly via a spring or other force producing means. 
     
     
         5 . A dual flush valve as claimed in  claim 1 , in which actuation of the operating system is via a single cable or similar type of control with two distinct positions to define the first and second actuation inputs. 
     
     
         6 . A dual flush valve as claimed in  claim 1 , in which the operating system includes first and second mechanisms for applying downward forces to the main valve assembly, movement of the operating system to a first position in response to the first actuation input causing the first mechanism for applying the first downward force to engage with the main valve assembly, whilst moving the operating system to a second position in response to the second actuation input causes the first mechanism to be disengaged or not to be selected and results in engagement of the second mechanism with the main valve assembly for applying the second downward force. 
     
     
         7 . A dual flush valve as claimed in  claim 1 , in which the mechanism for applying downward forces to the main valve assembly includes adjustment means configured to allow for independent adjustment of the first and second downward forces. 
     
     
         8 . A dual flush valve as claimed in  claim 1 , in which the operating system comprises sliding carrier movable from a lower, retracted position to first and second raised positions in response to the first and second actuation inputs respectively, the carrier being biased to the retracted position by a resilient member and carrying a lifting flange for contact with an abutment member on the main valve assembly to lift the main valve assembly off the valve seat as the carrier is moved from the retracted position to either one of the first and second raised positions. 
     
     
         9 . A dual flush valve as claimed in  claim 8 , in which the carrier also comprises a catch moveable between an engagement position, in which the catch is able to contact the main valve assembly to apply a first downward force on the main valve assembly as the carrier descends towards the retracted position under the bias of the resilient member when the actuation input is removed, and at least one retracted position, in which the catch member is unable to contact the main valve assembly, the operating system including a first lug for contact with the catch to move the catch to the engagement position as the carrier moves from the retracted position to the first raised position, and a second lug for contact with the catch as the carrier approaches its retracted position from a raised position to move the catch to a retracted position. 
     
     
         10 . A dual flush valve as claimed in  claim 9 , in which the second raised position is above the first raised position, the operating system having a third lug for contacting the catch as the carrier moves from the first raised position to the second raised position to move the catch to a retracted position. 
     
     
         11 . A dual flush valve as claimed in  claim 9 , in which the second raised position is lower than the first raised position such that during movement of the carrier to the second raised position, the first lug is not operative on the catch which remains in a retracted position. 
     
     
         12 . A dual flush valve as claimed in  claim 10 , in which the sliding carrier has a further abutment for contact with the valve member to apply a downward force on the main valve assembly as the carrier descends towards the retracted position from the second raised position under the bias of the resilient member when the actuation input is removed. 
     
     
         13 . A dual flush valve as claimed in  claim 12 , in which the operating system is configured such that on descent of the sliding carrier from the first raised position, the catch engages the main valve assembly at a first intermediate position of the carrier and that on descent of the sliding carrier from the second raised position, the further abutment contacts the raised main valve assembly at a second intermediate position of the carrier which is lower than the first intermediate position. 
     
     
         14 . A dual flush valve as claimed in  claim 13 , in which the guide structure comprises a housing within which the main valve assembly is movable between lowered and raised positions, the housing having a lower housing portion in which the valve seat is provided, a wall of the lower housing portion having openings through which immersion fluid can flow to the outlet when the main valve assembly is raised off the valve seat and the housing has an upper portion separated from the lower portion by a partition plate to define upper and lower chambers, the valve including a first vent means through which fluid may pass between the upper and lower chambers, a second vent means within the upper chamber between the main valve assembly and a wall of the upper housing portion through which fluid may flow from one end of the upper chamber to the other, a third vent means towards the upper end of the upper housing portion through which immersion fluid can flow between the upper chamber and the surrounding cistern, the main valve assembly including a central stem which projects upwardly be and the upper end of the housing for co-operation with the operating system, and wherein the central stem carries an abutment for contact with the catch when in the engaged position and the further abutment on the sliding carrier. 
     
     
         15 . A dual flush valve as claimed in  claim 12 , in which the further abutment is an adjustment screw. 
     
     
         16 . A dual flush valve as claimed in  claim 8 , in which the resilient member is a compression spring. 
     
     
         17 . (canceled)