To provide a float-valve device of a fuel tank in which characteristic of stability of a float valve is improved by raising a restoring pressure of the valve without throttling the flow-path area of a valve-seal surface.
The float-valve device includes a float valve 4 which is installed at a vapor discharge port 10a of the fuel tank 10 so as to open/close a valve-seal face 3 by buoyancy of fuel in the tank 10. Direction of pressure exerted by the float valve 4 on the valve-seal face 3 can be slanted relative to the direction of gravity Fw of the float valve 4 by inclining the valve-seal surface 3 by a specified angle θ relative to the direction of the gravity Fw acting on the float valve 4. Thus, the restoring pressure Pr of the float valve 4 is raised to increase the valve-closing force, and the characteristic of stability of the float valve 4 is improved to close the valve in a state in which the pressure in the tank 10 is higher than it is conventionally is.
Iwa Saki Kokuni
Akira Kurihara
Kawamata Sumio
Masakazu Ito
Shunichi Takahashi
Toshio Takamatsu