AIR-FUEL RATIO FEEDBACK CONTROL DEVICE FOR INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To improve converging responsiveness to a target air-fuel ratio in a device for performing a feedback control for an air-fuel ratio by calculating a linear item and a nonlinear item to be integrated by a sliding mode control. SOLUTION: The nonlinear item UNL is calculated as UNL=(gain 1)×(target air-fuel ratio - actual air-fuel ratio)/(|target air-fuel ratio - actual air-fuel ratio|)+UNL(OLD). The linear item UL is calculated as UL=(gain 2)×(target air-fuel ratio - actual air-fuel ratio)/actual air-fuel ratio. By the addition values, the feedback control is performed for the air-fuel ratio. The value of the nonlinear item UNL when the air-fuel ratio is converted in the vicinity of the target air-fuel ratio is initialized to an initial value for every target air fuel ratio.