Convection heating assisted engine-off natural vacuum test
First Claim
1. A method comprising:
- routing fuel vapors from a fuel tank to an evaporative emission system which is coupled to atmosphere, the fuel tank supplying fuel to an engine which propels a vehicle; and
during an engine-off condition and responsive to predetermined test conditions, sealing the fuel tank and the evaporative emission system from atmosphere, and routing engine heat through a passenger cabin of the vehicle to the fuel tank via a heater core to raise pressure in the fuel tank and the evaporative emission system.
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Accused Products
Abstract
Methods and systems are provided for conducting an engine off natural vacuum test in a vehicle in order to indicate the presence or absence of undesired evaporative emissions. In one example, a vehicle fuel system and evaporative emissions system are sealed from atmosphere, and responsive to a pressure increase below an expected threshold, the fuel system and evaporative emissions system are actively pressurized via circulating hot engine coolant to a heater core and blowing hot air through the vehicle cabin to the fuel system via a three way ventilation valve in the rear of the vehicle. In this way, false failures of EONV test procedures due to environmental factors and vehicle operator drive habits may be reduced, and unnecessary engine service may be avoided.
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Citations
20 Claims
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1. A method comprising:
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routing fuel vapors from a fuel tank to an evaporative emission system which is coupled to atmosphere, the fuel tank supplying fuel to an engine which propels a vehicle; and during an engine-off condition and responsive to predetermined test conditions, sealing the fuel tank and the evaporative emission system from atmosphere, and routing engine heat through a passenger cabin of the vehicle to the fuel tank via a heater core to raise pressure in the fuel tank and the evaporative emission system. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method comprising:
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routing fuel vapors from a fuel tank in a fuel system to an evaporative emission system which is coupled to atmosphere, the fuel tank supplying fuel to an engine which propels a vehicle; and following a vehicle-off event, in a first condition, sealing the fuel system and the evaporative emission system of the vehicle and monitoring pressure in the fuel system and the evaporative emission system; in a second condition, sealing the fuel system and the evaporative emission system, routing heated air via a heater core through a vehicle passenger cabin to the fuel tank to increase the pressure in the fuel system and the evaporative emission system, and monitoring the pressure in the fuel system and the evaporative emission system; wherein a pressure increase above an expected pressure threshold in both the first condition and the second condition indicates an absence of undesired evaporative emissions. - View Dependent Claims (14, 15, 16, 17)
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18. A system for a vehicle powered by at least an internal combustion engine comprising:
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a fuel tank configured within a fuel system; a fuel vapor canister, configured within an evaporative emission system, coupled to the fuel tank, further coupled to an engine intake via a canister purge valve, and further coupled to atmosphere via a canister vent valve; a fuel tank pressure transducer; an electric auxiliary pump; a heater core; a cabin blower; a vehicle passenger cabin; a ventilation duct coupled to a three-way ventilation valve, the three-way ventilation valve coupled to an air space surrounding the fuel tank in a first position, and coupled to atmosphere in a second position; a controller storing instructions in non-transitory memory that, when executed, cause the controller to; in a first condition, seal the fuel system and the evaporative emission system of the vehicle by commanding closed the canister vent valve and monitor pressure in the fuel system and the evaporative emission system; and in a second condition, seal the fuel system and the evaporative emission system by commanding closed the canister vent valve, route heated air through the vehicle passenger cabin to the fuel tank to increase the pressure in the fuel system and the evaporative emissions system, and monitor the pressure in the fuel system and the evaporative emission system; wherein a pressure increase above an expected pressure threshold in both the first condition and the second condition indicates an absence of undesired evaporative emissions; wherein both the first condition and the second condition comprise an engine-off event; and wherein routing heated air through the vehicle passenger cabin to the fuel tank comprises activating the electric auxiliary pump to circulate engine coolant to the heater core, activating the cabin blower to direct hot air emanating from the heater core to the vehicle passenger cabin, and configuring the three-way ventilation valve in the first position such that heated air flows from the heater core to the fuel tank, via the vehicle passenger cabin. - View Dependent Claims (19, 20)
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Specification