Patent ID: 8186372

Claim:
A fuel shut-off valve being disposed on the top of fuel tank, and opening and closing connector passage connecting the inside of the fuel tank to the outside, thereby communicating the inside of the fuel tank with the outside and shutting off the connector passage, the fuel shut-off valve comprising: a casing comprising a valve chamber communicating the inside of the fuel tank with the connector passage, and a first sealing portion surrounding the connector passage; a float being accommodated in the valve chamber of the casing, having a second sealing portion, and being exerted to increasing and decreasing buoyant force depending on liquid level within the valve chamber, thereby ascending and descending within the valve chamber; and an upper valve element being disposed on the top of the float, and being actuated by the float, which ascends and descends, to open and close the connector passage; the upper valve element comprising a valve body, and a ring-shaped seat member, the ring-shaped seat member being made from elastomer, being fixed to the valve body and making a connector bore therein, the connector bore having a top opening and a bottom opening; the ring-shaped seat member comprising a base, a holding portion which holds the valve body of the upper valve element between itself and the base, a seating portion which opens and closes the connector passage, and which defines the top opening of the connector bore of the ring-shaped seat member, a lip-shaped portion which seats on and separates away from the second sealing portion of the float, which protrudes down below beyond the bottom surface of the base and which defines the bottom opening of the connector bore of the ring-shaped seat member, and a thin-film-shaped portion which is disposed between the base and the lip-shaped portion, and which is deformable elastically upon being pressed by the second sealing portion of the float when the second sealing portion seats on the lip-shaped portion, wherein the bottom surface of the ring-shaped seat member's base makes a stopper surface, which defines the topmost position to which the float ascends by means of the buoyant force fully within the valve chamber of the casing, wherein the ring-shaped seat member further comprises a ring-shaped groove, which is disposed between the bottom surface of the base and the lip-shaped portion, wherein the thickness of the thin-film-shaped portion is smaller than that of the lip-shaped portion, and wherein the thin-film-shaped portion is disposed above the stopper surface.