| abstract |
A drain valve device (110) allowing operability and drainage performance to co-exist with each other, wherein a through-hole (128) in a cover body (126) is closed by a float (122) floating to the lower surface of the cover body (126), the state is maintained by using the buoyancy of the float, and the opening of a valve element (112) is also maintained, though the level of water in a tank is lowered since washing water in the tank flows through a drain port (108), the closed state of the through-hole (128) is maintained in a sleeve (124), when the level of water in the tank lowers to an air inlet hole (134) at the lower end of the sleeve, and air flows into the sleeve and washing water filling up the inside of the sleeve falls from the inside of the sleeve, whereby the float (122) loses the buoyancy and falls to close the valve element (112). |