Methods and systems for a pressureless fuel tank
AssigneeFord Global Technologies, LLC
InventorAed Dudar
Life of this patent
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Abstract
Methods and systems are provided for performing a reverse purge of an evaporative emissions canister in a vehicle with a sealed variable volume fuel tank. In one example, a method may comprise in response to an ambient temperature reducing during a diurnal temperature cycle, and further in response to the EVAP canister loaded with fuel vapors above a threshold, closing a valve positioned at an atmospheric port of the fuel tank and opening a fuel tank isolation valve. In one example, the fuel tank isolation valve may be in fluid communication between the fuel tank and the EVAP canister. In this way, it is possible to convert a sealed variable volume fuel tank to a vented pressurized fuel tank and initiate a reverse purge during the cooldown hours of the diurnal temperature cycle.
Claims16
A method to perform a reverse purge of an evaporative emissions canister in a vehicle with a sealed variable volume fuel tank with bellows, comprising:
- detecting an ambient temperature is reducing during a diurnal temperature cycle, and further detecting a loading of the evaporative emissions canister with vapors is above a threshold while the ambient temperature is reduced, and
- in response to detecting the ambient temperature reducing during the diurnal temperature cycle, and further detecting the loading of the evaporative emissions canister with vapors is above the threshold while the ambient temperature is reducing, closing a valve fluidly coupled with an atmospheric port of the sealed variable volume fuel tank to reduce contraction and expansion of the bellows,
- wherein the closing of the valve is during a vehicle off condition, wherein the reverse purge draws air in from the atmosphere, then through the evaporative emissions canister, and then through a fuel tank isolation valve and into the fuel tank exterior to the bellows, and wherein during operation with the valve open, the bellows communicate fluidically with the atmosphere.
A vehicle system, comprising:
- a variable volume fuel tank, an air gap of the fuel tank sealed except for only a fuel tank isolation valve port and a fuel filler pipe, the fuel tank further comprising:
- bellows;
- a port coupling an internal volume of the bellows to atmosphere;
- and
- a valve positioned between an atmospheric port and atmosphere;
- an evaporative emissions canister;
- a fuel tank isolation valve in fluid communication between the fuel tank and the evaporative emissions canister;
- and
- a controller, the controller comprising computer readable memory with instructions stored therein configured to:
- in response to an ambient temperature reducing during a diurnal temperature cycle while a loading of the evaporative emissions canister with vapors is above a threshold, close the valve to reduce contraction and expansion of the bellows.
A vehicle system, comprising:
- a variable volume fuel tank, an air gap of the tank sealed except for only a fuel tank isolation valve port, the fuel tank further comprising:
- bellows;
- an atmospheric port coupling an internal volume of the bellows to atmosphere;
- and
- a valve positioned between the atmospheric port and atmosphere;
- an evaporative emissions canister;
- a fuel tank isolation valve in fluid communication between the fuel tank and the evaporative emissions canister;
- and
- a computer readable memory with instructions stored therein configured to carry out valve control during vehicle off conditions, including closing the valve and opening the fuel tank isolation valve during select vehicle off conditions based on ambient temperature variations and during a vehicle off condition,
- wherein the instructions are further configured to close the valve in response to the ambient temperature reducing during a diurnal temperature cycle while a loading of the canister with vapors is above a threshold.
Dependencies are inferred from the claim text.