Systems and methods for improving vehicle engine stability
AssigneeFord Global Technologies, LLC
InventorAed Dudar
Life of this patent
Estimating the term…
Abstract
Methods and systems are provided for depressurizing a fuel tank of a vehicle by routing fuel tank vapors to an engine for combustion. In one example, a method may include reducing a pressure in the fuel tank by routing vapors from the fuel tank through a portion of a fuel vapor storage canister and, in response to an indication of a condition of degraded engine stability, re-routing the vapors from the fuel tank through an entirety of the fuel vapor storage canister. In this way, under conditions of degraded engine stability, a rate at which fuel tank vapors are directed to the engine may be reduced, which may thus mitigate the condition of degraded engine stability without aborting the operation to reduce the fuel tank pressure.
Claims20
A method comprising:
- reducing a pressure in a fuel tank by routing vapors from the fuel tank through a portion of a fuel vapor canister positioned in an evaporative emissions system of a vehicle and not through an entirety of the fuel vapor canister;
- and
- in response to an indication of a condition of degraded stability of an engine, re-routing the vapors from the fuel tank through the entirety of the fuel vapor canister.
A method comprising:
- reducing a pressure in a fuel tank by duty cycling a fuel tank isolation valve positioned in a conduit coupling the fuel tank to a fuel vapor canister between a first position and a second position;
- and
- in response to an indication of a condition of degraded stability of an engine, continuing to reduce the pressure by duty cycling the fuel tank isolation valve between the first position and a third position.
A system for a hybrid vehicle, comprising:
- a fuel tank that is selectively fluidically coupled to an evaporative emissions system that includes a fuel vapor canister via a three-way fuel tank isolation valve, the fuel vapor canister further selectively fluidically coupled to an engine via a canister purge valve;
- and
- a controller with computer readable instructions stored on non-transitory memory that when executed while the engine is operating to combust air and fuel, cause the controller to:
- reduce a pressure in the fuel tank by controlling the fuel tank isolation valve to direct fuel tank vapors through a portion of the fuel vapor canister and then to the engine under conditions of an absence of degraded stability of the engine;
- and
- reduce the pressure in the fuel tank by controlling the fuel tank isolation valve to direct the fuel tank vapors through an entirety of the fuel vapor canister and then to the engine under conditions of a presence of degraded stability of the engine.
Dependencies are inferred from the claim text.