Abstract: A method for a vehicle, comprising: depressurizing a fuel tank while restricting access to a fuel fill line responsive to receiving a refueling request from a refueling request module located external to a vehicle cabin; and allowing access to the fuel fill line responsive to the fuel tank pressure decreasing below a threshold. In this way, all of the steps of a refueling procedure can be carried out entirely outside of a vehicle.

Abstract: An evaporative emission control system for a plug-in hybrid electric vehicle that indicates the level of loading of a carbon canister of the system. The system has multiple thermocouples positioned space apart from each other along a vapor flow path within the carbon canister. A controller is connected to each thermocouple, which monitors the temperature of the thermocouples. The controller indicates the level of saturation of the carbon canister based on certain pre-determined temperature criteria.

Abstract: Methods and systems are provided for improving canister purging during the limited engine operation time in a hybrid electric vehicle. Prior to a transition into an engine-on mode, a canister heater is operated to heat the canister to an optimum temperature based on vehicle operating conditions. Upon transition into the engine-on mode, fuel vapors released from the heated canister are purged to an engine intake.

Abstract: Methods and systems for fuel system leak detection in a hybrid electric vehicle using a fuel reservoir are disclosed. In one example approach, a method comprises, during an engine off condition, delivering fuel from a fuel tank into a reservoir while the fuel tank is vented to atmosphere, discontinuing delivering fuel into the reservoir, sealing the fuel tank from atmosphere, and following the sealing, indicating a leak based on a pressure increase in the fuel tank from a pressure when sealed from venting.

Abstract: Methods and systems are provided for identifying leaks on each of a fuel tank and a canister side of a fuel system using a single leak check module. A position of a switching valve coupled in the vapor line of the fuel system is adjusted to selectively couple the leak check module to either the fuel tank or the canister. Leak is detected based on a change in pressure at a reference orifice of the leak check module following applying of vacuum from a vacuum pump.

Abstract: Systems and methods are described for a canister purge valve. A method comprises rotating an armature within a valve body in the canister purge valve as the canister purge valve opens and closes during a purge operation. The armature is encircled at a first end by an elastomer seal with multiple angled wings that enable rotation of the armature about a central longitudinal axis during the purge operation.

Abstract: Embodiments for detecting fuel events are presented. In an embodiment, a method comprises performing an action responsive to a fuel event indicated based on output from a hydrocarbon sensor positioned between a fuel tank and a fuel vapor canister. In this way, the hydrocarbon sensor may be used to detect fuel events and engine operation may be adjusted accordingly.

Abstract: A method for a fuel system, comprising: during a first condition, purging fuel vapor from a fuel vapor canister to a fuel vapor accumulator; and then during a second condition, evacuating fuel vapor from the fuel vapor accumulator to a fuel tank. The fuel vapor accumulator increases the volume of the fuel system, providing a temporary storage for desorbed fuel vapor. In this way, canister breakthrough of hydrocarbons can be mitigated, thereby reducing bleed emissions.

Abstract: A system for a vehicle, comprising: a tank pressure control valve coupled in a first conduit between a fuel tank and a fuel vapor canister; a refueling valve coupled in a second, different, conduit between the fuel tank and the fuel vapor canister, the second conduit in parallel to the first conduit. In this way, two smaller, less complex valves may be utilized to control fuel tank vapor purging and fuel tank depressurization during refueling. This in turn may lower system cost and increase system functionality.

Abstract: Methods and systems for detecting a leak in a canister purge valve are disclosed. In one example approach, a method comprises indicating a leak in response to a temperature change in a fuel vapor canister coupled to a fuel tank in an emission control system while the engine is in operation and a purge valve is closed.

Abstract: A method for a fuel system coupled to an engine comprising: under vacuum conditions, opening the fuel vapor canister purge valve, and generating pressure pulsations in a conduit coupled to the fuel vapor canister purge valve by opening and closing a fuel vapor canister vent valve one or more times while maintaining the fuel vapor canister purge valve open. In this way, contaminants and/or debris that may prevent the canister purge valve from closing completely may be dislodged and evacuated to the intake manifold.

Abstract: Methods and systems are provided for accurately confirming fuel tank depressurization before unlocking a fuel door to enable refueling. Following a refueling request, a fuel system may be sealed from the atmosphere while one or more fuel system valves are adjusted to divert fuel tank pressure or vacuum to an engine intake. Depressurization may be inferred based on the presence of air or vapor flow into the intake as sensed by a manifold airflow sensor.

Abstract: A system for an engine, comprising: a fuel vapor canister coupled to a fuel tank; a thermal jacket comprising a phase-change material, the thermal jacket spatially sheathing the fuel vapor canister; and an engine coolant passage positioned to transfer thermal energy between engine coolant and the phase-change material. In this way, the phase-change material may buffer the temperature of the fuel vapor canister by absorbing heat generated during hydrocarbon adsorption, and returning the heat to the vapor canister during hydrocarbon desorption. By coupling the phase-change material to engine coolant, the thermal capacity of the thermal jacket can be increased, as heated coolant can thus transfer thermal energy to the phase-change material to replace the thermal energy transferred to the canister during hydrocarbon desorption.

Abstract: A system for an engine, comprising: a fuel tank; a thermal regulator comprising a phase-change material, the thermal regulator coupled to the fuel tank; and an engine coolant passage positioned to transfer thermal energy between engine coolant and the phase-change material. In this way, the temperature of the fuel tank may be managed passively by the phase-change material, and actively by engine coolant, thereby allowing heat energy to be shunted away from the fuel tank, cooling the fuel within the fuel tank, and reducing fuel vapor concentration, thus enabling a fuel vapor canister with a reduced size.

Abstract: Systems and methods for operating an engine with a fuel vapor recovery system are disclosed. In one example approach, a method for an engine with a fuel vapor recovery system including a multi-tubular fuel vapor canister comprises directing air through a first set of adsorbent passages in the fuel vapor canister to purge fuel vapor therefrom while not directing air through a second set of adsorbent passages in the fuel vapor canister; and directing air through the second set of adsorbent passages to purge fuel vapor therefrom while not directing air through the first set of adsorbent passages.

Abstract: A method for a vehicle, comprising: depressurizing a fuel tank while restricting access to a fuel fill line responsive to receiving a refueling request from a refueling request module located external to a vehicle cabin; and allowing access to the fuel fill line responsive to the fuel tank pressure decreasing below a threshold. In this way, all of the steps of a refueling procedure can be carried out entirely outside of a vehicle.

Abstract: Methods and systems are provided for improving air intake system hydrocarbon trap purging during engine-off time in a hybrid electric vehicle. One method includes opening the throttle during vehicle motion under battery operation and allowing airflow through the trap to purge its contents into the fuel canister via the canister purge valve. Upon transition into the engine-on mode, fuel vapors are released from the canister into the engine intake.

Abstract: A method for a fuel system, comprising: indicating a leak in a fuel tank following applying a vacuum to the fuel tank by running a vacuum pump in a first direction; then purging a fuel vapor canister to the fuel tank by running the vacuum pump in a second direction, opposite the first direction. In this way, the fuel vapor canister may be purged of its contents following a fuel system leak check. This may reduce bleed emissions while increasing the efficiency of the vehicle, as the engine does not need to be turned on in order to purge the canister.

Abstract: A method for a plug-in hybrid electric vehicle, comprising: during a first condition, including an engine-off condition and the plug-in hybrid electric vehicle coupled to an external power source; heating a fuel vapor canister based on a fuel tank vacuum; and opening a fuel tank isolation valve to draw heated vapors into a fuel tank. In this way, a passive purge operation may be executed, thereby purging the fuel vapor canister without forcing the engine to turn on. Thus, the vehicle may be operated at peak fuel economy without increasing emissions.

Abstract: A method for a vehicle fuel system, comprising: during an engine-off condition, including an ambient temperature within a threshold range, operating a cooling fan to increase a fuel tank vacuum; and indicating leaks in the vehicle fuel system based on the increased vacuum. In this way, an EONV test may be run at mild ambient temperatures which would not otherwise result in the development of adequate fuel tank vacuum to pass the EONV test.