Method and system for determining and controlling a/f ratio in lean engines
AssigneeFord Global Technologies, LLC
InventorsGarth M. Meyer, Joseph R. Asik
Life of this patent
Estimating the term…
Abstract
A method and system for determining and controlling air/fuel ratio during lean engine operation relies on applying a small fuel pulse width modulation to the engine and synchronously measuring the effect of the modulation on related engine event periods. This effect is utilized in estimating air/fuel ratio, which is then compared to the desired air/fuel ratio. The difference between the estimated air/fuel ratio and the desired air/fuel ratio is used in controlling the air/fuel ratio to the desired air/fuel ratio.
Claims18
A method for determining air/fuel ratio of an internal combustion engine having a fuel injector and controlling the engine accordingly, the method comprising:
- sensing an engine coolant temperature and generating a corresponding temperature signal;
- sensing a cylinder air mass and generating a corresponding air mass signal;
- modulating a base fuel pulse width to the fuel injector according to a predetermined event schedule including a rich fuel pulse width relative to the base fuel pulse width and a lean fuel pulse width relative to the base fuel pulse width based on the temperature signal and the air mass signal;
- determining a rich event time in response to the rich fuel pulse width and a lean event time in response to the lean fuel pulse width;
- determining a metric based on the rich event time and the lean event time;
- determining the air/fuel ratio based on the metric, the temperature signal and the air mass signal;
- and
- controlling the engine based on the determined air/fuel ratio.
A system for determining air/fuel ratio of an internal combustion engine having a fuel injector and controlling the engine accordingly, the system comprising:
- a temperature sensor for sensing an engine coolant temperature and generating a corresponding temperature signal;
- an air mass sensor for sensing a cylinder air mass and generating a corresponding air mass signal;
- and
- control logic operative to modulate a base fuel pulse width to the fuel injector according to a predetermined event schedule including a rich fuel pulse width relative to the base fuel pulse width and a lean fuel pulse width relative to the base fuel pulse width based on the temperature signal and the air mass signal, determine a rich event time in response to the rich fuel pulse width and a lean event time in response to the lean fuel pulse width, determine a metric based on the rich event time and the lean event time, determine the air/fuel ratio based on the metric, the temperature signal and the air mass signal, and control the engine based on the determined air/fuel ratio.
An article of manufacture for an automotive vehicle having an internal combustion engine, a fuel injector for injecting fuel into the engine, a temperature sensor for sensing an engine coolant temperature and generating a corresponding temperature signal, and an air mass sensor for sensing a cylinder air mass and generating a corresponding air mass signal, the article comprising:
- a computer storage medium having a computer program encoded therein for modulating a base fuel pulse width to the fuel injector according to a predetermined event schedule including a rich fuel pulse width relative to the base fuel pulse width and a lean fuel pulse width relative to the base fuel pulse width based on the temperature signal and the air mass signal, determining a rich event time in response to the rich fuel pulse width and a lean event time in response to the lean fuel pulse width, determining a metric based on the rich event time and the lean event time, determining the air/fuel ratio based on the metric, the temperature signal and the air mass signal, and controlling the engine based on the determined air/fuel ratio.
Dependencies are inferred from the claim text.