System and methods for purging a fuel vapor canister
First Claim
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1. A method for purging a fuel vapor canister coupled to an engine intake and a vent line inlet, comprising:
- with a controller, responsive to a canister load decreasing below a first threshold, reversing a direction of air flow through the fuel vapor canister via an actuator while maintaining purge air intake at the vent line inlet and purge gas delivery to the engine intake, the fuel vapor canister load being determined from sensed conditions.
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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.
16 Citations
20 Claims
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1. A method for purging a fuel vapor canister coupled to an engine intake and a vent line inlet, comprising:
with a controller, responsive to a canister load decreasing below a first threshold, reversing a direction of air flow through the fuel vapor canister via an actuator while maintaining purge air intake at the vent line inlet and purge gas delivery to the engine intake, the fuel vapor canister load being determined from sensed conditions. - View Dependent Claims (2, 3, 4)
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5. 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, such that air flows through the fuel vapor canister in a first direction; and with a controller, responsive to a fuel vapor canister load decreasing below a first threshold, reversing a direction of airflow within the fuel vapor canister by coupling the second fuel vapor canister port to the engine intake and coupling the first fuel vapor canister port to the fresh air source with actuators, the fuel vapor canister load being determined from operating conditions determined from sensors. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13)
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14. 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, the fuel vapor canister load being determined from operating conditions; 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 (15, 16, 17, 18, 19, 20)
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Specification