System and method of controlling fuel delivery during positive valve overlap operation of an engine start
AssigneeFord Global Technologies, LLC
InventorsSteve Magner, Xiaoying Zhang, John Rollinger, Mrdjan Jankovic, Sue Wagers
Life of this patent
Estimating the term…
Abstract
An approach is provided for compensating engine fueling during starting conditions in which positive valve overlap is enabled early in the start. In one example, the valve timing is adjusted to increase positive overlap during cold starting conditions, and fuel adjustments are provided to compensate for the evaporation effects of the increased residual push-back.
Claims15
A method for controlling fuel injection into an engine of a vehicle, the engine having at least a variable intake valve timing system, the method comprising:
- cold starting the engine with the variable valve timing system at a default position;
- before the engine warms to a warm-up temperature, adjusting the variable intake valve timing system to generate an increase in positive valve overlap of at least one cylinder;
- adjusting a fuel injection amount in response to said increase in positive valve overlap, where said adjusting the fuel injection amount provides a decrease in injected fuel to account for an increase in fuel evaporating from the intake valve and/or the intake port as engine temperature warms;
- and
- adjusting spark timing in response to said adjusting of the variable intake valve timing system and further to maintain engine idle speed.
A method for controlling fuel injection into an engine of a vehicle, the engine having a variable valve timing system, the method comprising:
- starting engine with the variable valve timing system at a default position;
- before the engine warms to a warm-up temperature, adjusting the variable valve timing system to increase positive valve overlap of at least one cylinder;
- and
- adjusting a fuel injection amount in response to said increase in positive valve overlap, said adjustment of fuel providing a decrease in injected fuel to account for an increase in fuel evaporating from the intake valve, said fuel adjustment based on an amount of pushback residual flow due to said positive valve overlap, where said residual flow is proportional to a square of an amount of overlap between intake and exhaust valves, and then later further decreasing injected fuel to account for transient fuel evaporating from the intake port as the engine temperature warms.
A method for controlling fuel injection into an engine of a vehicle, the engine having a variable valve timing system, the method comprising:
- starting engine with the variable valve timing system at a default position and with a fuel film accumulated on an intake valve of the variable valve timing system;
- before the engine warms to a warm-up temperature, adjusting the variable valve timing system to increase positive valve overlap of at least one cylinder;
- pushing back combusted cylinder gasses past the intake valve into an intake manifold to heat the intake valve;
- evaporating the fuel film via said heating of the intake valve;
- inducting at least some evaporated fuel from the film into the cylinder;
- and
- adjusting a fuel injection amount in response to said increase in positive valve overlap, said adjustment of fuel providing a decrease in injected fuel to account for an increase in fuel evaporating from the intake valve as the engine temperature warms.
Dependencies are inferred from the claim text.