Systems and methods for improving fuel vapor canister purging operations in a PHEV
AssigneeFord Global Technologies, LLC
InventorAed Dudar
Life of this patent
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Abstract
Methods and systems are provided for rationalizing a hydrocarbon sensor in a hybrid vehicle, the hydrocarbon sensor used for feed-forward air/fuel ratio control during fuel vapor canister purging events. In one example, a method comprises routing blow-by gasses from a crankcase of an engine of the vehicle to an intake manifold of the engine and then to a fuel vapor storage canister, and indicating whether the hydrocarbon sensor is functioning as desired based on a magnitude of a response of the hydrocarbon sensor during the routing. In this way, the hydrocarbon sensor may be diagnosed under conditions when the canister is substantially free from fuel vapors, and where engine run-time is limited.
Claims20
A method comprising:
- routing blow-by gasses from a crankcase of an engine of a vehicle to an intake manifold of the engine, and then to a fuel vapor storage canister positioned in an evaporative emissions system of the vehicle;
- and
- indicating whether a hydrocarbon sensor used for feed-forward air/fuel ratio control during purging of the fuel vapor storage canister is functioning as desired based on a response of the hydrocarbon sensor during the routing.
A method comprising:
- conducting a diagnostic for a hydrocarbon sensor coupled to a purge line positioned between an intake manifold of an engine and a fuel vapor storage canister positioned in an evaporative emissions system of a vehicle driven by the engine, by rotating the engine unfueled at a key-off event to direct blow-by gasses from a crankcase of the engine to the intake manifold, and then routing the blow-by gasses through the purge line past the hydrocarbon sensor en route to the fuel vapor storage canister, where the hydrocarbon sensor is indicated to be degraded responsive to a hydrocarbon sensor response to the blow-by gasses less than a threshold hydrocarbon sensor response during the routing the blow-by gasses past the hydrocarbon sensor.
A system for a hybrid electric vehicle, comprising:
- an engine including an intake, an intake manifold, and an exhaust system;
- a throttle positioned in the intake;
- a positive crankcase ventilation system including a positive crankcase ventilation valve positioned in a positive crankcase ventilation line, for selectively fluidically coupling a crankcase of the engine to the intake manifold;
- a motor;
- an evaporative emissions system including a fuel vapor storage canister, the fuel vapor storage canister selectively fluidically coupled to atmosphere via a canister vent valve positioned in a vent line;
- a vacuum pump positioned in a vacuum pump conduit in parallel with the vent line;
- a first check valve positioned in the vacuum pump conduit between the vacuum pump and the vent line downstream of the canister vent valve;
- a second check valve positioned in the vacuum pump conduit between the vacuum pump and the vent line upstream of the canister vent valve;
- a canister purge valve, positioned in a purge line, the canister purge valve selectively fluidically coupling the intake manifold to the fuel vapor storage canister;
- a hydrocarbon sensor positioned in the purge line between the fuel vapor storage canister and the canister purge valve;
- and
- a controller storing instructions in non-transitory memory that, when executed, cause the controller to:
- at a key-off event where a canister loading state of the fuel vapor storage canister is below a threshold canister loading state and where a drive cycle just prior to the key-off event included engine operation:
- command open the throttle and command closed the canister vent valve;
- operate the motor to rotate the engine unfueled to route blow-by gasses in the crankcase to the intake manifold via the positive crankcase ventilation valve in an at least partially open position, and further operating the vacuum pump to draw the blow-by gasses past the hydrocarbon sensor via the canister purge valve commanded to an open position;
- and
- indicating the hydrocarbon sensor is degraded responsive to an output of the hydrocarbon sensor below a threshold output, while drawing the blow-by gasses past the hydrocarbon sensor.
Dependencies are inferred from the claim text.