System and method including a fuel tank isolation valve

A fuel tank isolation valve consisting essentially of:

• a housing defining a chamber, the housing including a first port adapted to be connected in fluid communication with a fuel vapor collection canister, a second port adapted to be connected in fluid communication with a fuel tank, and an interior partition defining an aperture, the interior partition separating the housing into first and second sections;
• a diaphragm movable with respect to the housing, the diaphragm dividing the second section of the housing into first and second segments;
• and
• a resilient element biasing the diaphragm toward a first configuration dividing the chamber into three sub-chambers and substantially preventing fluid flow between the first and second ports;
• wherein the chamber at the first configuration comprises a first sub-chamber, a second sub-chamber, and a third sub-chamber, the first sub-chamber extending from the first port to the aperture and being defined by the interior partition, the diaphragm, and the first section of the housing, the second sub-chamber extending from the aperture to the second and being defined by the interior partition, the diaphragm, and the second segment of the second section of the housing, and the third sub chamber enclosing the resilient element and being defined by the diaphragm and the first segment of the second section of the housing.

A fuel tank isolation valve comprising:

• a housing defining a chamber, the housing including a first port adapted to be connected in fluid communication with a fuel vapor collection canister, a second port adapted to be connected in fluid communication with a fuel tank, and an interior partition defining an aperture, the interior partition separating the housing into first and second sections, and the interior partition including a check valve providing unidirectional fluid communication from the first sub-chamber to the second sub-chamber;
• a diaphragm movable with respect to the housing, the diaphragm dividing the second section of the housing into first and second segments;
• and
• a resilient element biasing the diaphragm toward a first configuration dividing the chamber into three sub-chambers and substantially preventing fluid flow between the first and second ports:
• wherein the chamber at the first configuration comprises a first sub-chamber, a second sub-chamber, and a third sub-chamber, the first sub-chamber extending from the first port to the aperture and being defined by the interior partition, the diaphragm, and the first section of the housing, the second sub-chamber extending from the aperture to the second port and being defined by the interior partition, the diaphragm, and the second segment of the second section of the housing, and the third sub chamber enclosing the resilient element and being defined by the diaphragm and the first segment of the second section of the housing.

A method of controlling fuel vapor flow between an evaporative emission space of a fuel tank and a fuel vapor collection canister, the method comprising:

• providing a fuel tank isolation valve consisting essentially of:
• a housing defining a chamber, the housing including a first port being adapted for the fuel vapor communication with the evaporative emission space of the fuel tank and including a second port being adapted for fuel vapor communication with the fuel vapor collection canister;
• a diaphragm including a central portion, a peripheral portion being fixed with respect to the housing, and an intermediate portion extending between the central and peripheral portions, the diaphragm movable with respect to the housing between a first configuration and a second configuration, the first configuration dividing the chamber into three sub-chambers and substantially preventing fluid flow between the first and second ports, and the second configuration dividing the chamber into two sub-chambers and permitting generally unrestricted fluid flow between the first and second ports;
• and
• a resilient element biasing the diaphragm toward the first configuration;
• moving the diaphragm to the first configuration in response to a second pressure level at the second port acting on the central portion of the diaphragm, the second pressure level being below atmospheric pressure;
• and
• moving the diaphragm to the second configuration in response to a first pressure level at the first port acting on the intermediate portion of the diaphragm, the first pressure level being above atmospheric pressure.

The method of controlling fuel vapor flow between an evaporative emission space of a fuel tank and a fuel vapor collection canister, the method comprising:

• providing a fuel tank isolation valve including:
• a housing defining a chamber, the housing including a first port being adapted for fuel vapor communication with the evaporative emission space of the fuel tank and including a second port being adapted for fuel vapor communication with the fuel vapor collection canister;
• a diaphragm including a central portion, a peripheral portion being fixed with respect to the housing, and an intermediate portion extending between the central and peripheral portions, the diaphragm movable with respect to the housing between a first configuration and a second configuration, the first configuration dividing the chamber into three sub-chambers and substantially preventing fluid flow between the first and second ports, and the second configuration dividing the chamber into two sub-chambers and permitting generally unrestricted fluid flow between the first and second ports, and
• a resilient element biasing the diaphragm toward the first configuration:
• moving the diaphragm to the first configuration in response to a second pressure level at the second port acting on the central portion of the diaphragm, the second pressure level being below atmospheric pressure;
• moving the diaphragm to the second configuration in response to a first pressure level at the first port acting on the intermediate portion of the diaphragm, the first pressure level being above atmospheric pressure;
• and
• equalizing pressure at the first and second ports in response to a third pressure level at the first port, the third pressure level being below atmospheric pressure.

A method of controlling fuel vapor flow between an evaporative emission space of a fuel tank and a fuel vapor collection canister, the method comprising:

• providing a fuel tank isolation valve including:
• a housing defining a chamber, the housing including a first port being adapted for fuel vapor communication with the evaporative emission space of the fuel tank and including a second port being adapted for fuel vapor communication with the fuel vapor collection canister;
• a diaphragm movable with respect to the housing between a first configuration and a second configuration, the first configuration dividing the chamber into three sub-chambers and substantially preventing fluid flow between the first and second ports, and the second configuration dividing the chamber into two sub-chambers and permitting generally unrestricted fluid flow between the first and second ports;
• and
• a resilient element biasing the diaphragm toward the first configuration;
• moving the diaphragm to the first configuration in response to a second pressure level at the second port, the second pressure level being below atmospheric pressure;
• moving the diaphragm to the second configuration in response to a first pressure level at the first port, the first pressure level being above atmospheric pressure;
• and
• equalizing pressure at the first and second ports in response to a third pressure level at the first port, the third pressure level being below atmospheric pressure
• wherein the first pressure level is at least one inch of water above atmospheric pressure, and the third pressure level is at least six inches of water below atmospheric pressure.

A method of controlling fuel vapor flow between an evaporative emission space of a fuel tank and a fuel vapor collection canister, the method comprising:

• providing a fuel tank isolation valve including:
• a housing defining a chamber, the housing including a first port being adapted for fuel vapor communication with the evaporative emission space of the fuel tank and including a second port being adapted for fuel vapor communication with the fuel vapor collection canister;
• a diaphragm including a central portion, a peripheral portion being fixed with respect to the housing, and an intermediate portion extending between the central and peripheral portions, the diaphragm movable with respect to the housing between a first configuration and a second configuration, the first configuration dividing the chamber into three sub-chambers and substantially preventing fluid flow between the first and second ports, and the second configuration dividing the chamber into damping and fuel vapor flow, sub-chambers and permitting generally unrestricted fluid flow between the first and second ports;
• and
• a resilient element biasing the diaphragm toward the first configuration;
• moving the diaphragm to the first configuration in response to a second pressure level at the second port acting on the central portion of the diaphragm, the second pressure level being below atmospheric pressure;
• moving the diaphragm to the second configuration in response to a first pressure level at the first port acting on the intermediate portion of the diaphragm, the first pressure level being above atmospheric pressure;
• and
• damping the moving of the diaphragm, the damping being in response to rapid increases in the first pressure level and providing a flow restrictor regulating fluid communication between the damping sub-chamber and ambient conditions exterior to the housing.