SYSTEM AND METHODS FOR PURGING A FUEL VAPOR CANISTER
First Claim
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1. A method for purging a fuel vapor canister, comprising:
- responsive to a canister load decreasing below a first threshold, reversing a direction of air flow through the fuel vapor canister while maintaining purge air intake at a vent line inlet.
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Abstract
A method for purging a fuel vapor canister, comprising: responsive to a canister load decreasing below a first threshold, reversing a direction of air flow through the fuel vapor canister while maintaining purge air intake at a vent line inlet. By reversing the direction of air flow through the fuel vapor canister, canister regions that would normally retain fuel vapor during a purge event may realize increased desorption when the air flow direction is reversed. In this way, the efficiency of a purge event may be increased and bleed emissions may be reduced.
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Citations
20 Claims
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1. A method for purging a fuel vapor canister, comprising:
responsive to a canister load decreasing below a first threshold, reversing a direction of air flow through the fuel vapor canister while maintaining purge air intake at a vent line inlet. - View Dependent Claims (2, 3, 4, 5)
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6. A method for purging a fuel vapor canister, comprising:
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coupling a first fuel vapor canister port to an engine intake; coupling a second fuel vapor canister port to a fresh air source; opening a canister purge valve coupled between the first fuel vapor canister port and the engine intake; and responsive to a fuel vapor canister load decreasing below a first threshold, coupling the second fuel vapor canister port to the engine intake and coupling the first fuel vapor canister port to the fresh air source. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14)
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15. A system for an engine, comprising:
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a fuel vapor canister comprising a fuel vapor canister buffer; a purge line coupling the fuel vapor canister to an engine intake via a canister purge valve; a vent line coupling the fuel vapor canister to a fresh air source; a canister vent valve coupled between the fuel vapor canister and the vent line, the canister vent valve operable between a first conformation and a second conformation; a reversing valve coupled between the fuel vapor canister buffer and the purge line, the reversing valve operable between a first conformation and a second conformation; and a controller comprising instructions stored in non-transitory memory, that when executed, cause the controller to; draw air through the fuel vapor canister with the canister vent valve in the first conformation and with the reversing valve in the first conformation; responsive to a fuel vapor canister load decreasing below a first threshold, draw air through the fuel vapor canister with the canister vent valve in the second conformation and with the reversing valve in the second conformation; and responsive to the fuel vapor canister load decreasing below a second threshold, lower than the first threshold, ceasing drawing air through the fuel vapor canister. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification