Patent ID: 6073073
Filing Date: 2000-06-06
Classification: F02D

Abstract:
A system for controlling an air/fuel ratio of an internal combustion engine, comprising:an air/fuel ratio detecting means for detecting an air/fuel ratio of exhaust gas generated by the engine at least based upon an output of an air/fuel ratio sensor located in an exhaust system of the engine;engine operating condition detecting means for detecting engine operating conditions including at least engine speed and engine load;basic fuel supply amount calculating means for calculating a basic amount of fuel supply to be supplied to the engine based upon at least the detected engine operating conditions;desired value predetermining means for predetermining a desired value as a fixed value;controlled variable determining means for determining a controlled variable based upon the detected air/fuel ratio and a desired air/fuel ratio as at least one of a) a ratio between the detected air/fuel ratio and the desired air/fuel ratio and b) a difference between the detected air/fuel ratio and the desired air/fuel ratio such that the desired value is the fixed value;feedback correction coefficient calculating means operatively coupled to said air/fuel ratio detecting means and having an adaptive controller which receives as inputs the desired value and the controlled variable and an adaptation mechanism which estimates adaptive parameters, said feedback correction coefficient calculating means for calculating a feedback correction coefficient as an output based upon at least the adaptive parameters for correcting the basic amount of fuel supply calculated by said basic fuel supply amount calculating means such that the controlled variable converges to the desired value;output fuel amount determining means, operatively coupled to said basic fuel amount calculating means and feedback correction coefficient calculating means, for correcting the basic amount of fuel supply calculated by said basic fuel supply amount calculating means by the feedback correction coefficient to determine an output amount of fuel supply; andfuel supplying means, operatively coupled to said output fuel amount determining means, for supplying the output amount of fuel supply to the engine.