Vacuum-actuated vapor recovery system

Claim 1

A system for recovering fuel vapors discharged from a vehicle fuel system during refueling, the vehicle fuel system including a fuel tank, a filler neck having a mouth and communicating with the fuel tank, and canister means for processing fuel vapor, the system comprising delivery means for conducting fuel vapor between the fuel tank and the canister means, valve means for normally blocking flow of fuel vapor through the delivery means, the valve means including one portion exposed to fuel vapor conducted by the delivery means and a remaining portion, the valve means being movable relative to the delivery means between a flow-blocking position and flow-delivering positions in response to exposure of the valve means to a differential pressure created by differing magnitudes of pressure communicated to the one portion and the remaining portion and exposure of the one portion to pressure having a magnitude in excess of a predetermined threshold level, partition means for dividing the filler neck into an outer chamber communicable with the atmosphere through the filler neck mouth and an inner chamber in fluid communication with the fuel tank, the partition means including means for sealingly admitting a fuel-dispensing nozzle into the inner chamber without coupling the inner and outer chambers in fluid communication during refueling to preserve any negative pressure which develops in the inner chamber in response to introduction of liquid fuel into the inner chamber through a fuel-dispensing nozzle during refueling, and a negative pressure-transmission conduit for communicating negative pressure in the inner chamber to the remaining portion of the valve means so that vacuum developed in the inner chamber during refueling is applied to the remaining portion of the valve means to lower the magnitude of pressure communicated to the remaining portion of the valve means by the negative pressure-transmission conduit relative to the magnitude of pressure communicated to the one portion of the valve means by the delivery means to establish the differential pressure so that a movement-inducing load resulting from the pressure communicated to the one portion having a magnitude in excess of the predetermined threshold level is applied to move the valve means to a flow-delivering position.

Claim 2

A system for recovering fuel vapors discharged from a vehicle fuel system during refueling, the vehicle fuel system including a fuel tank, a filler neck having a mouth and communicating with the fuel tank, and canister means for processing fuel vapor, the system comprising delivery means for conducting fuel vapor between the fuel tank and the canister means, valve means for normally blocking flow of fuel vapor through the delivery means, the valve means including one portion exposed to fuel vapor conducted by the delivery means and a remaining portion, the valve means being movable relative to the delivery means between a flow-blocking position and flow-delivering positions in response to exposure of the valve means to a differential pressure created by differing magnitudes of pressure communicated to the one portion and the remaining portion and exposure of the one portion to pressure having a magnitude in excess of a predetermined threshold level, partition means for dividing the filler neck into an outer chamber communicable with the atmosphere through the filler neck mouth and an inner chamber in fluid communication with the fuel tank, the partition means including means for sealingly admitting a fuel-dispensing nozzle into the inner chamber without coupling the inner and outer chambers in fluid communication during refueling to preserve any negative pressure which develops in the inner chamber in response to introduction of liquid fuel into the inner chamber through a fuel-dispensing nozzle during refueling, and a negative pressure-transmission conduit for communicating negative pressure in the inner chamber to the remaining portion of the valve means so that vacuum developed in the inner chamber during refueling is applied to the remaining portion of the valve means to lower the magnitude of pressure communicated to the remaining portion of the valve means by the negative pressure-transmission conduit relative to the magnitude of pressure communicated to the one portion of the valve means by the delivery means to establish the differential pressure so that a movement-inducing load resulting from the pressure communicated to the one portion having a magnitude in excess of the predetermined threshold level is applied to move the valve means to a flow-delivering position.

Claim 5

A system for recovering fuel vapors discharged from a vehicle fuel system during refueling, the vehicle fuel system including a fuel tank and canister means for processing fuel vapor, the system comprising delivery means for conducting fuel vapor between the fuel tank and the canister means, valve means for selectively blocking flow of fuel vapor through the delivery means, the valve means being movable between a flow-blocking position and flow-delivery positions, venting control chamber means for containing fuel vapor in a predetermined region communicating with the valve means and permitting fuel vapor to exert a closing force on the valve means causing the valve means to move to its flow-blocking position, thereby blocking discharge of fuel vapor in the fuel tank to the canister means via the delivery means, partition means for dividing the filler neck into an outer chamber communicable with the atmosphere through the filler neck mouth and an inner chamber in fluid communication with the fuel tank, the partition means including means for sealingly admitting a fuel-dispensing nozzle into the inner chamber without coupling the inner and outer chambers in fluid communication during refueling to preserve any negative pressure developed in the inner chamber caused by introduction of liquid fuel into the inner chamber using a fuel-dispensing nozzle during refueling, and means for communicating negative pressure in the inner chamber to the predetermined region during introduction of liquid fuel into the inner chamber.

Claim 6

A system for recovering fuel vapors discharged from a vehicle fuel system during refueling, the vehicle fuel system including a fuel tank and canister means for processing fuel vapor, the system comprising delivery means for conducting fuel vapor between the fuel tank and the canister means, valve means for selectively blocking flow of fuel vapor through the delivery means, the valve means being movable between a flow-blocking position and flow-delivery positions, venting control chamber means for containing fuel vapor in a predetermined region communicating with the valve means and permitting fuel vapor to exert a closing force on the valve means causing the valve means to move to its flow-blocking position, thereby blocking discharge of fuel vapor in the fuel tank to the canister means via the delivery means, partition means for dividing the filler neck into an outer chamber communicable with the atmosphere through the filler neck mouth and an inner chamber in fluid communication with the fuel tank, the partition means including means for sealingly admitting a fuel-dispensing nozzle into the inner chamber without coupling the inner and outer chambers in fluid communication during refueling to preserve any negative pressure developed in the inner chamber caused by introduction of liquid fuel into the inner chamber using a fuel-dispensing nozzle during refueling, and means for communicating negative pressure in the inner chamber to the predetermined region during introduction of liquid fuel into the inner chamber.