초록

A refueling shut-off system is provided for use with a vehicle fuel system including a fuel tank, a fuel tank filler neck, and a fuel vapor recovery canister. The system includes a fill-limit vent valve and a flow-control valve.

대표청구항 ▼

The invention claimed is: 1. A refueling shut-off system for use with a fuel vapor recovery canister and a fuel tank formed to include an interior region for containing fuel vapor and liquid fuel, the system comprising a filler neck adapted to be coupled to fuel tank at a first end, the filler neck

The invention claimed is: 1. A refueling shut-off system for use with a fuel vapor recovery canister and a fuel tank formed to include an interior region for containing fuel vapor and liquid fuel, the system comprising a filler neck adapted to be coupled to fuel tank at a first end, the filler neck being formed to include an open mouth at an opposite second end and a fuel-conducting passageway extending between the first and second ends and communicating with an interior region of the fuel tank, a fuel vapor discharge conduit formed to include an outlet end adapted to mate with the fuel vapor recovery canister to discharge fuel vapor flowing in the fuel vapor discharge conduit into the fuel vapor recovery canister, a vent unit adapted to be coupled to the fuel tank and configured to receive and regulate flow of fuel vapor discharged from the interior region of the fuel tank to the fuel vapor discharge conduit for delivery to the fuel vapor recovery canister, the vent unit including a vent line formed to include an inlet and an outlet, a vent channel formed to include an outlet coupled to the fuel vapor discharge conduit to discharge any fuel vapor flowing in the vent channel into the fuel vapor discharge conduit, a normally closed flow-control valve formed to include an inlet port coupled to the outlet of the vent line and an outlet port coupled to an inlet end of the fuel vapor discharge conduit to allow fuel vapor discharged from the normally closed flow-control valve to flow into the fuel vapor discharge conduit and toward a fuel vapor recovery canister coupled to the outlet end of the fuel vapor discharge conduit, a normally opened fill-limit vent valve formed to include an inlet port adapted to be exposed to fuel vapor extant in the interior region of the fuel tank and an outlet port coupled to the inlet of the vent line to allow fuel vapor discharged from the normally opened fill-limit vent valve to reach the normally closed flow-control valve, and a normally opened first rollover valve formed to include an inlet port adapted to be exposed to fuel vapor extant in the interior region of the fuel tank and an outlet port coupled to an inlet formed in the vent channel to allow fuel vapor discharged from the normally opened first rollover valve to flow into the fuel vapor discharge conduit and toward a fuel vapor recovery canister coupled to the outlet end of the fuel vapor discharge outlet, and a fuel vapor recirculation conduit configured to interconnect the vent line and the fuel-conducting passageway formed in the filler neck in fluid communication, the fuel vapor recirculation conduit including a one-way liquid-fuel check valve configured to allow flow of fuel vapor discharged from the vent line through the fuel vapor recirculation conduit into the fuel-conducting passageway formed in the filler neck and to block flow of liquid fuel passing from the fuel-conducting passageway into the fuel vapor recirculation conduit into the vent line. 2. The system of claim 1, wherein the normally closed flow-control valve includes a valve stopper housing having an interior region receiving the outlet end of the vent line therein, a stopper mounted for movement in the interior region of the valve stopper housing between a closed position mating with the outlet end of the vent line to block flow of fuel vapor from the vent line into the fuel vapor discharge conduit and an opened position disengaging the outlet end of the vent line to allow fuel vapor discharged from the outlet end of the vent line to flow into the fuel vapor discharge conduit, and spring means for yieldably urging the stopper normally to the closed position and allowing the stopper to move from the closed position to the opened position in response to discharge of pressurized fuel vapor having a pressure magnitude in excess of a predetermined minimum from the normally opened fill-limit vent valve into the vent line during fuel tank refueling so that the pressurized fuel vapor exiting the fuel tank through the normally opened fill-limit vent valve is discharged into the fuel vapor discharge conduit via the normally closed flow-control valve while the stopper is moved to the opened position. 3. The system of claim 2, wherein the normally opened fill-limit vent valve includes a valve closure housing formed to include the inlet and outlet ports, a closure arranged to move in the valve closure housing between an opened position allowing flow of fuel vapor exiting the interior region of the fuel tank into the vent line and a closed position blocking flow of fuel vapor extant in the interior region of the fuel tank into the vent line, and means for moving the closure from a normally opened position to the closed position in response to accumulation of liquid fuel in the interior region of the fuel tank to a first predetermined amount defining a fill-limit vent valve closure level in the fuel tank to block flow of pressurized fuel vapor from a vapor space provided in the interior region of the fuel tank into the vent line included in the vent unit. 4. The system of claim 3, wherein the fuel vapor recirculation conduit is configured to provide vacuum generator means for applying a mid-level aspiration-induced vacuum to the vent line while the closure of the normally opened fill-limit vent valve is located in the closed position upon accumulation of liquid fuel in the interior region of the fuel tank to a second predetermined amount greater than the first predetermined amount and defining a flow-control valve closure level and in response to downward flow of liquid fuel in the fuel-conducting passageway of the filler neck toward the first end thereof to cause the stopper to move from the opened position to assume the closed position before a relatively higher high-level aspiration-induced vacuum is generated in the fuel-conducting passageway by continued downward flow of liquid fuel in the fuel-conducting passageway of the filler neck to activate a vacuum-sensitive nozzle shut-off mechanism associated with a fuel-dispensing pump nozzle inserted into the fuel-conducting passageway through the open mouth of the filler neck and used to establish the downward flow of liquid fuel in the fuel-conducting passageway of the filler neck. 5. The system of claim 4, wherein the fuel vapor recirculation conduit is configured to provide high-level vacuum generator means for applying a high-level aspiration-induced vacuum that is greater than the mid-level aspiration-induced vacuum to the vent line while the closure of the normally opened fill-limit vent valve is located in the closed position upon accumulation of liquid fuel in the interior region of the fuel tank to a third predetermined amount greater than the second predetermined amount and in response to continued downward flow of liquid fuel in the fuel-conducting passageway of the filler neck to generate a vacuum in the fuel-conducting passageway sufficient to activate a vacuum-sensitive nozzle shut-off mechanism associated with a fuel-dispensing pump nozzle inserted into the fuel-conducting passageway through the open mouth of the filler neck and used to establish the downward flow of liquid fuel in the fuel-conducting passageway of the filler neck. 6. The system of claim 4, wherein the filler neck is formed to include at the first end an inlet check valve and at the open mouth a sealed nozzle admission port configured to admit a fuel-discharge outlet of a fuel-dispensing pump nozzle into the fuel-conducting passageway of the filler neck to establish a sealed connection therebetween so as to establish a sealed fuel-transfer conduit located in the fuel-conducting passageway between the inlet check valve and the sealed nozzle admission port and arranged to receive a vacuum-sensitive nozzle shut-off mechanism associated with a fuel-dispensing pump nozzle inserted into the fuel-conducting passageway through the sealed nozzle admission port and wherein the fuel vapor recirculation conduit is arranged to open into the sealed fuel transfer conduit established in the fuel-conducting passageway of the filler neck. 7. The system of claim 3, wherein the valve stopper housing of the normally closed flow-control valve includes a ceiling and a side wall arranged to extend downwardly from the ceiling and arranged to extend around the outlet end of the vent line, the stopper is a diaphragm made of a sealing material and having a peripheral edge coupled to the side wall to locate the stopper in a position under the ceiling of the valve stopper housing and above the outlet end of the vent line and to define a spring chamber located between the ceiling and the stopper, and the spring means is located in the spring chamber, and wherein the normally closed flow-control valve further includes passageway means for placing the spring chamber and the fuel vapor discharge conduit in fluid communication to allow fuel vapor extant in the spring chamber to be expelled to the fuel vapor discharge conduit during movement of the stopper from the closed position to the opened position. 8. The system of claim 7, wherein the normally opened fill-limit vent valve is adapted to be coupled to the fuel tank to extend into the interior region of the fuel tank and is arranged to underlie the normally closed flow-control valve. 9. The system of claim 1, further comprising an exhaust conduit formed to include an outlet coupled to the fuel vapor discharge conduit and a normally opened second rollover valve formed to include an inlet port adapted to be exposed to fuel vapor extant in the interior region of the fuel tank and an outlet port coupled to an inlet of the exhaust conduit to allow fuel vapor discharged from the vapor space provided in the interior region of the fuel tank to flow into the fuel vapor discharge conduit toward a fuel vapor recovery canister coupled to the outlet end of the fuel vapor discharge outlet. 10. A refueling shut-off system for use with a fuel vapor recovery canister and a fuel tank formed to include an interior region for containing fuel vapor and liquid fuel, the system comprising a filler neck adapted to be coupled to fuel tank at a first end, the filler neck being formed to include an open mouth at an opposite second end and a fuel-conducting passageway extending between the first and second ends and communicating with an interior region of the fuel tank, a fuel vapor discharge conduit formed to include an outlet end adapted to mate with the fuel vapor recovery canister to discharge fuel vapor flowing in the fuel vapor discharge conduit into the fuel vapor recovery canister, a vent unit adapted to be coupled to the fuel tank and configured to receive and regulate flow of fuel vapor discharged from the interior region of the fuel tank to the fuel vapor discharge conduit for delivery to the fuel vapor recovery canister, the vent unit including a vent line formed to include an inlet and an outlet, a normally closed flow-control valve formed to include an inlet port coupled to the outlet of the vent line and an outlet port coupled to an inlet end of the fuel vapor discharge conduit to allow fuel vapor discharged from the normally closed flow-control valve to flow into the fuel vapor discharge conduit and toward a fuel vapor recovery canister coupled to the outlet end of the fuel vapor discharge conduit, and a normally opened fill-limit vent valve formed to include an inlet port adapted to be exposed to fuel vapor extant in the interior region of the fuel tank and an outlet port coupled to the inlet of the vent line to allow fuel vapor discharged from the normally opened fill-limit vent valve to reach the normally closed flow-control valve, and a fuel vapor recirculation conduit configured to interconnect the vent line and the fuel-conducting passageway formed in the filler neck in fluid communication to communicate an aspiration-induced vacuum generated in the fuel-conducting passageway during fuel tank refueling to the normally closed flow-control valve. 11. The system of claim 10, wherein the normally closed flow-control valve includes a valve stopper housing having an interior region receiving the outlet end of the vent line therein, a stopper mounted for movement in the interior region of the valve stopper housing between a closed position mating with the outlet end of the vent line to block flow of fuel vapor from the vent line into the fuel vapor discharge conduit and an opened position disengaging the outlet end of the vent line to allow fuel vapor discharged from the outlet end of the vent line to flow into the fuel vapor discharge conduit, and spring means for yieldably urging the stopper normally to the closed position and allowing the stopper to move from the closed position to the opened position in response to discharge of pressurized fuel vapor having a pressure magnitude in excess of a predetermined minimum from the normally opened fill-limit vent valve into the vent line during fuel tank refueling so that the pressurized fuel vapor exiting the fuel tank through the normally opened fill-limit vent valve is discharged into the fuel vapor discharge conduit via the normally closed flow-control valve while the stopper is moved to the opened position. 12. The system of claim 11, wherein the normally opened fill-limit vent valve includes a valve closure housing formed to include the inlet and outlet ports, a closure arranged to move in the valve closure housing between an opened position allowing flow of fuel vapor exiting the interior region of the fuel tank into the vent line and a closed position blocking flow of fuel vapor extant in the interior region of the fuel tank into the vent line, and means for moving the closure from a normally opened position to the closed position in response to accumulation of liquid fuel in the interior region of the fuel tank to a first predetermined amount defining a fill-limit valve closure level in the fuel tank to block flow of pressurized fuel vapor from a vapor space provided in the interior region of the fuel tank into the vent line included in the vent unit. 13. The system of claim 12, wherein the fuel vapor recirculation conduit is configured to provide means for applying a mid-level vacuum to the vent line while the closure of the normally opened fill-limit valve is located in the closed position in response to downward flow of liquid fuel in the fuel-conducting passageway of the filler neck toward the first end thereof to cause the stopper to move from the opened position to assume the closed position before a relatively higher high-level vacuum is generated in the fuel-conducting passageway by continued downward flow of liquid fuel in the fuel-conducting passageway of the filler neck to activate a vacuum-sensitive nozzle shut-off mechanism associated with a fuel-dispensing pump nozzle inserted into the fuel-conducting passageway through the open mouth of the filler neck and used to establish the downward flow of liquid fuel in the fuel-conducting passageway of the filler neck. 14. The system of claim 11, wherein the valve stopper housing of the normally closed flow-control valve includes a ceiling and a side wall arranged to extend downwardly from the ceiling and arranged to extend around the outlet end of the vent line, the stopper is a diaphragm made of a sealing material and having a peripheral edge coupled to the side wall to locate the stopper in a position under the ceiling of the valve stopper housing and above the outlet end of the vent line and to define a spring chamber located between the ceiling and the stopper, the spring means is located in the spring chamber, and wherein the normally closed flow control valve further includes passageway means for placing the spring chamber and the fuel vapor discharge conduit in fluid communication to allow fuel vapor extant in the spring chamber to be expelled to the fuel vapor discharge conduit during movement of the stopper from the closed position to the opened position. 15. A process for operating a vehicle fuel system including a fuel tank, a filler neck coupled to the tank, a fuel vapor recovery canister, and a fuel vapor conductor communicating fuel vapor from the fuel tank to the fuel vapor recovery canister, in series, first through a normally opened fill-limit vent valve and second through, when opened, a normally closed flow-control valve, the process comprising the steps of opening the normally closed flow-control valve to allow pressurized fuel vapor to flow from the fuel tank through the fill-limit vent valve, the flow-control valve, and the fuel vapor conductor to the fuel vapor recovery canister during discharge of liquid fuel from a fuel-dispensing pump nozzle into the fuel tank through the filler neck as long as liquid fuel extant in the fuel tank remains below a fill-limit vent valve closure level in the fuel tank associated with a first volume of liquid fuel in the fuel tank, closing the normally opened fill-limit vent valve in response to accumulation of liquid fuel in the fuel tank to an amount equal to the first volume of liquid fuel once liquid fuel rises to the fill-limit vent valve closure level, and using a vacuum of a first magnitude generated in the filler neck to close the normally closed flow-control valve that had been opened during the opening step to allow the vacuum generated in the filler neck to rise to a higher second magnitude sufficient to activate a vacuum-sensitive nozzle shut-off mechanism associated with the fuel-dispensing pump nozzle to halt further discharge of liquid fuel into the fuel tank through the filler neck.