| 摘要 |
<p>PROBLEM TO BE SOLVED: To enable ventilation while opening under small negative pressure, and surely close a valve without mechanical excessive load at the time of overpressure by controlling a valve member through a film on which pressure in a fuel tank is acted. SOLUTION: Reciprocating motion of a valve tappet 5 is linked to a vibration of a film 6 through a valve lever 10. When negative pressure to an atmosphere exists in a control chamber 7, in a film 6, a capacity of the control chamber 7 is reduced, a position is vibrated, and the valve lever 10 is pushed down against return force of a coil spring by a film disk 9 mounted on the valve lever 10. In this time, the valve tappet 5 is separated from a valve seat 12 through the valve lever 10, and fluid connection between a ventilation conduit 8 and a fuel tank 2 is released. When pressure between the control chamber 7 and a circumferential pressure is balanced by ventilation of the fuel tank 2, the valve tappet 5 is pushed to a closing position by the coil spring 13, and a closing member 11 is pushed on the valve seat 12. It is thus possible to carry out ventilation having a good condition with pressure of the fuel tank 2.</p> |
