Method for improved air-fuel ratio control in engines
AssigneeFord Global Technologies, LLC
InventorsGopichandra Surnilla, David Karl Bidner
Life of this patent
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Abstract
An engine control system of an internal combustion engine coupled to a NOx trap uses a measured air-fuel ratio downstream of the NOx trap to control engine air-fuel ratio. The measured air-fuel is only used for feedback when it indicates a value away from stoichiometry. Thus, NOx and oxygen storage effects that cause inlet air-fuel ratio to be different from exit air-fuel ratio do not cause degraded feedback air-fuel ratio control.
Claims19
An article of manufacture comprising:
- a computer storage medium having a computer program encoded therein for an emission control device coupled to an internal combustion engine with a sensor coupled to an exhaust gas of the engine downstream of the emission control device, said computer storage medium comprising:
- code for providing a first output signal of the sensor indicative of a first quantity of the exhaust gas and a second output of the sensor indicative of a second quantity of the exhaust gas;
- code for determining a desired engine air-fuel ratio based on the second output signal;
- code for indicating whether said desired air-fuel ratio has changed;
- code for adjusting a fuel injection amount into the engine to provide said desired engine air-fuel ratio based on the first output signal;
- and
- code for suspending said adjusting for a predetermined duration after said indication, wherein said predetermined duration is based on an oxygen storage amount of the emission control device when said desired air-fuel ratio is changed from rich to lean of stoichiometry, and said predetermined duration is based on said oxygen storage amount and a NOx storage amount of the emission control device when said desired air-fuel ratio is changed from lean to rich of stoichiometry.
A method for an emission control device coupled to an internal combustion engine with a sensor coupled to an exhaust gas of the engine downstream of the emission control device, the method comprising:
- providing a first output signal of the sensor indicative of a first quantity of the exhaust gas and a second output of the sensor indicative of a second quantity of the exhaust gas;
- determining a desired engine air-fuel ratio based on the second output signal;
- and
- adjusting a fuel injection amount into the engine to provide said desired engine air-fuel ratio based on the first output signal when the first output signal indicates an exhaust air-fuel ratio away from stoichiometry.
A method for an emission control device coupled to an internal combustion engine with a sensor coupled to an exhaust gas of the engine downstream of the emission control device, the method comprising:
- providing a first output signal of the sensor indicative of a first quantity of the exhaust gas and a second output of the sensor indicative of a second quantity of the exhaust gas;
- determining a desired engine air-fuel ratio based on the second output signal;
- indicating whether said desired air-fuel ratio has changed;
- adjusting a fuel injection amount into the engine to provide said desired engine air-fuel ratio based on the first output signal;
- and
- suspending said adjusting for a predetermined duration after said indication.
Dependencies are inferred from the claim text.