System and methods for controlling air fuel ratio
AssigneeFord Global Technologies, LLC
InventorsEric Krengel, Steven Schwochert
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Abstract
Methods and system for controlling air-fuel ratios in an internal combustion engine are disclosed. One embodiment comprises, adjusting a sensor calibration correction value of an exhaust sensor upstream of a catalyst based on an exhaust sensor downstream of the catalyst. The adjustment of the sensor calibration correction value takes advantage of the fact that certain aromatic hydrocarbons causing errors in the reading of the upstream sensor are not present at the downstream sensor due to sufficient catalytic activity of a catalyst positioned between the sensors.
Claims11
A method for adjusting a fuel injection amount to one or more cylinders of an engine, comprising:
- operating the engine in steady-state conditions with engine temperature below a threshold while catalyst activity is above a threshold,
- responsive to operating the engine in the steady-state conditions with the engine temperature below the threshold while the catalyst activity is above the threshold, determining a calibration error of a first oxygen sensor within an exhaust system of the engine based on information from a second oxygen sensor within the exhaust system, the first oxygen sensor positioned upstream of a catalyst, and the second oxygen sensor positioned downstream of the catalyst, where both sensors measure exhaust gas with a same actual air-fuel ratio;
- adjusting a determined air-fuel ratio based on the calibration error;
- and
- adjusting the fuel injection amount to the one or more cylinders based on the adjusted air-fuel ratio.
A system for controlling air-fuel ratio of an engine, comprising:
- a fuel injection system configured to deliver fuel to one or more cylinders of the engine;
- an exhaust system coupled to the one or more cylinders;
- a catalyst coupled to the exhaust system;
- a first oxygen sensor coupled upstream of the catalyst;
- a second oxygen sensor coupled downstream of the catalyst;
- and
- a control system including a computer readable storage medium, the medium including non-transitory instructions thereon, the control system receiving communication from the first and second exhaust gas oxygen sensors, the medium comprising instructions for:
- responsive to selected engine operating conditions, determining a sensor calibration correction value and adjusting an air-fuel ratio based on the sensor calibration correction value, where the sensor calibration correction value is determined based on a difference between an output of the first oxygen sensor and an output of the second oxygen sensor, the outputs concurrently read from the respective sensors;
- and
- adjusting a fuel injection amount to the one or more cylinders in response to the adjusted air-fuel ratio, wherein the selected engine operating conditions comprise the catalyst being in an active state while the engine is operating at a temperature below a threshold temperature.
Dependencies are inferred from the claim text.