System and methods for engine-off natural vacuum tests
First Claim
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1. A method for a vehicle, comprising:
- during a first condition;
receiving an indication of a first engine-off event;
receiving an indication that retaining heat during the first engine-off event will increase a likelihood of an engine-off natural vacuum test executing successfully;
following the first engine-off event, closing a canister vent valve based on the heat retention indication without initiating the engine-off natural vacuum test;
receiving an indication of an engine-on event; and
opening the canister vent valve following the engine-on event; and
during a second condition, following the first condition;
receiving an indication of a vehicle-off event, including a second engine-off event;
following the vehicle-off event, closing the canister vent valve based on the vehicle-off event; and
theninitiating the engine-off natural vacuum test.
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Abstract
A method for a vehicle, comprising: during a first condition, closing a canister vent valve responsive to an engine-off event without initiating an engine-off natural vacuum test; during a second condition, following the first condition, closing the canister vent valve responsive to a vehicle-off event; and then initiating an engine-off natural vacuum test. In this way, the completion percentage of the engine-off natural vacuum test will increase.
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Citations
17 Claims
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1. A method for a vehicle, comprising:
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during a first condition; receiving an indication of a first engine-off event; receiving an indication that retaining heat during the first engine-off event will increase a likelihood of an engine-off natural vacuum test executing successfully; following the first engine-off event, closing a canister vent valve based on the heat retention indication without initiating the engine-off natural vacuum test; receiving an indication of an engine-on event; and opening the canister vent valve following the engine-on event; and during a second condition, following the first condition; receiving an indication of a vehicle-off event, including a second engine-off event; following the vehicle-off event, closing the canister vent valve based on the vehicle-off event; and
theninitiating the engine-off natural vacuum test. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for a vehicle, comprising:
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at a first vehicle-off event, determining a likelihood of a next vehicle-on event during a predetermined window; closing a canister vent valve at the first vehicle-off event if the determined likelihood is above a threshold; and maintaining a status of a fuel system at the first vehicle-off event if the determined likelihood is below the threshold. - View Dependent Claims (11, 12, 13, 14)
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15. A method, comprising:
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during vehicle-on, engine-off operation where a hybrid vehicle is en route to a destination and responsive to an indication to perform an engine-off natural vacuum test at a subsequent vehicle-off event, closing a canister vent valve and maintaining a canister purge valve closed; responsive to vehicle-on, engine-on operation, opening the canister vent valve; and responsive to the subsequent vehicle-off event, closing the canister vent valve and executing the engine-off natural vacuum test. - View Dependent Claims (16, 17)
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Specification