Fuel shut-off device

A fuel shut-off device for controlling an internal pressure of a fuel tank and preventing effusion of fuel liquid from the fuel tank, said fuel shut-off device comprising:

• a casing having a connection port adapted to be coupled with an external apparatus;
• a partition wall for dividing a space in said casing into an upper chamber having said connection port and a lower chamber, said lower chamber having a first opening for introducing fuel vapor and fuel liquid from the fuel tank, said partition wall having a connection hole to connect said upper chamber with said lower chamber;
• an upper chamber division plate disposed in said upper chamber to be vertically movable therein for dividing said upper chamber into a first upper section and a second upper section arranged below said first upper section, said upper chamber division plate having a second opening which allows flow of said fuel vapor between said first upper section and said second upper section, said upper chamber division plate further including a conduit penetrating through said connection hole, said conduit connecting said first upper section and said lower chamber;
• first force applying means disposed in said first upper section of said upper chamber for applying a first pressing force to said upper chamber division plate toward said partition wall;
• a first valve mechanism disposed in said first upper section for decreasing the internal pressure of the fuel tank, said first valve mechanism having a first valve plug for opening and closing a top of said conduit responsive to the internal pressure of the fuel tank;
• a float valve disposed in said lower chamber for closing a bottom of said conduit in response to a flow of fuel liquid into said lower chamber;
• and
• a second valve mechanism disposed in said second upper section for decreasing the internal pressure of the fuel tank, said second valve mechanism having a second valve plug for opening and closing a path between said conduit and said connection hole responsive to the internal pressure of the fuel tank,
• wherein said first valve plug is seated on an upper surface of said upper chamber division plate, said first valve plug receiving an internal pressure of said upper chamber and said first pressing force of said first force applying means toward said upper chamber division plate, said first valve plug having a first pressure receiving area for receiving internal pressure of said lower chamber through said conduit in a direction to separate said first valve plug from said upper surface of said upper chamber division plate;
• said second valve plug moving with said conduit to seat on an upper surface of said partition wall, said second valve plug receiving the internal pressure of said upper chamber and said first pressing force of said first force applying means transmitted via said first valve plug and said upper chamber division plate to press said second valve plug against said upper surface of said partition wall, said second valve plug having a second pressure receiving area for receiving the internal pressure of said lower chamber through said path in a direction to separate said second valve plug from said upper surface of said partition wall, said second pressure receiving area of said second valve plug being smaller than said first pressure receiving area of said first valve plug,
• said first and second valve mechanism being constructed and arranged to receive substantially the same pressing force.