Patent ID: 7865979

Claim:
A toilet tank flush valve structure, for use with a toilet tank having a floor formed with an outlet hole, the flush valve structure comprising: a valve base for installation in the outlet hole formed in the floor of the toilet tank, the valve base defining a water outflow passage having an upper end and a lower end and including a first valve member at the upper end of the water outflow passage, and a float assembly that is movable relative to the valve base between a sealing position in which a second valve member at a lower end of the float assembly engages the first valve member in sealing relationship and a flushing position in which the second valve member is spaced upwardly from the first valve member, and wherein the float assembly comprises an outer shell that is open downwards and has a lower edge at which the shell is provided with said second valve member, and a closure member within the outer shell and cooperating with the outer shell to define a float chamber, and wherein the closure member is adjustable in position relative to the outer shell, whereby the float chamber is adjustable in volume.