Patent ID: 8918922

Claim:
A water discharge valve device for a flush water tank, the flush water tank being configured to store therein flush water for flushing a toilet bowl, comprising: a water discharge valve which includes a valve element for opening and closing a discharge port provided in a bottom wall of the flush water tank, and a control casing for controlling an up-down movement of the valve element; a casing module which includes a peripheral wall extending upwardly from the bottom wall of the flush water tank while surrounding peripheries of the discharge port and the control casing of the water discharge valve, to define an upwardly open space therebetween, a flushing mode-switching opening formed to penetrate through the peripheral wall, and a switching valve attached to the peripheral wall and adapted to open and close the flushing mode-switching opening, the switching valve being operatable on the basis of the flushing mode, wherein the casing module is used irrespective of when a toilet is a siphon type flush toilet or a wash-down type toilet, wherein the casing module is configured so that when the switching valve moves in the direction for closing the flushing mode-switching opening, water discharge is performed in a partial flushing mode and wherein the casing module is configured so that when the switching valve moves in a direction for opening the flushing mode-switching opening, water discharge is performed in a full flushing mode in which the amount of flush water to be discharged from the discharge port is increased as compared to the partial flushing mode by an amount of flush water in a region of the flush water tank outside the casing module flowing into an inside of the casing module through the flushing mode-switching opening and then being discharged from the discharge port; and a communication port formed in a peripheral plane extending from the control casing of the water discharge valve to the discharge port, to provide fluid communication between the casing module and the discharge port, wherein the flushing mode-switching opening of the casing module is provided at a height position equal to or lower than that of an upper end of the communication port.