Toilet cistern dual flush valve

Abstract

The invention provides a toilet cistern dual flush valve ( 10 ) operable selectively in a full flush mode in which a relatively large volume of water is discharged from the cistern or a partial flush mode in which a relatively small volume of water is discharged from the cistern. The dual flush valve ( 10 ) comprises a stem ( 36 ) carrying a valve closure ( 38 ) seatable on an outlet from the cistern, means to raise the stem ( 70, 72,74 ), buoyant means ( 50 ) attached to the stem ( 36 ) which in the full flush mode maintains the stem ( 36 ) in the open position until the relatively large volume of water has been discharged and the buoyant means ( 50 ) loses buoyancy whereafter the stem ( 36 ) descends under gravity to the closed position, and means ( 54 ) which operates in the partial flush mode to add sufficient mass to the stem when the relatively small volume of water has been discharged causing the stem ( 36 ) to descend to the closed position.

1 . A toilet cistern dual flush valve operable selectively in a full flush mode in which a relatively large volume of water is discharged from the cistern or a partial flush mode in which a relatively small volume of water is discharged from the cistern, the valve comprising: 
 a valve stem carrying a valve closure seatable on an outlet from the cistern and movable between a raised, open position in which the closure is spaced from the outlet and a lowered, closed position in which the closure seats on the outlet,    means operable in both full and partial flush modes to raise the stem,    operatively buoyant means attached to the stem which in the full flush mode maintains the stem in the open position until the relatively large volume of water has been discharged and the buoyant means loses buoyancy whereafter the stem descends under gravity to the closed position, and    means which operates in the partial flush mode to add sufficient further mass to the stem when the relatively small volume of water has been discharged, to cause the stem to descend to the closed position.    
     
     
         2 . A toilet cistern dual flush valve according to  claim 1  wherein the means operable to raise the stem includes actuators that are selectively, manually operable to initiate the full or the partial flush mode.  
     
     
         3 . A toilet cistern dual flush valve according to  claim 2  wherein the actuators are actuating handles.  
     
     
         4 . A toilet cistern dual flush valve according to  claim 2  wherein the actuators are actuating buttons.  
     
     
         5 . A toilet cistern dual flush valve according to any one of  claims 1  to  4  wherein the operatively buoyant means includes a main float.  
     
     
         6 . A toilet cistern dual flush valve according to any one of  claims 1  to  5  wherein the means which operate in the partial flush mode to add further mass to the stem includes an upper float unit.  
     
     
         7 . A toilet cistern dual flush valve according to any one of  claims 1  to  6  wherein the valve stem includes upper and lower collars.  
     
     
         8 . A toilet cistern dual flush valve according to any one of claims  2  to  claim 7  including linkages extending between the actuators and the upper float unit such that operation of either actuator raises the upper float unit into abutment with an upper collar on the stem thereby raising the stem to the open position.  
     
     
         9 . A toilet cistern dual flush valve according to  claim 8  wherein the linkages include a toggle attachable pivotally to the upper float unit, the toggle including a detent such that operation of the relevant actuator to initiate a partial flush causes the toggle to pivot to a position in which the detent engages the lower collar and adds the mass of the upper float unit to the valve stem when water in the cistern has dropped to a level at which the upper float unit loses buoyancy.  
     
     
         10 . A toilet cistern dual flush valve according to  claim 9  wherein the upper float unit includes a water reservoir to accommodate a volume of water to provide gravitational mass.  
     
     
         11 . A toilet cistern dual flush valve according to any one of  claims 5  to  10  wherein the main float and/or the upper float unit include inverted cup shapes to accommodate air.  
     
     
         12 . A toilet cistern dual flush valve according to any one of  claims 5  to  10  wherein the inverted cup shapes of the main float and/or the upper float unit include closed cell foam.  
     
     
         13 . A toilet cistern dual flush valve according to any one of  claims 7  to  12  wherein each linkage includes a telescopic construction to lengthen or shorten the linkage.  
     
     
         14 . A toilet cistern dual flush valve according to  claim 13  wherein the telescopic construction includes a catch and a ratchet.  
     
     
         15 . A toilet cistern dual flush valve substantially as herein described and illustrated in the drawings.