AIR-FUEL RATIO CONTROL DEVICE OF INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To avoid emission deterioration caused by evaporation purging as much as possible and to simply perform relatively exact purge learning. SOLUTION: A basic fuel injection quantity after correction is obtained from relation that, on the assumption that an cylinder intake air volume is constant, a product of a command fuel injection quantity and a detected air-fuel ratio becomes equal to a product of a target air-fuel ratio and a target basic fuel injection quantity for bringing an actual air-fuel ratio of an engine to the target air-fuel ratio. A correction coefficient KF for the basic fuel injection quantity is calculated from a ratio of the basic fuel injection quantity after correction and a basic fuel injection quantity before correction to correct the basic fuel injection quantity. A filter time-constant of low pass filtering for calculation of a KF value at the time of purge is set smaller than that at the time of non-purge. In the purge, in addition to a KF value using a filter of a small time-constant provided for actual air-fuel ratio control, a KF value at the time of non-purge using a filter of a large time-constant is also calculated and purge learning is conducted with use of the KF value at the time of non-purge. COPYRIGHT: (C)2006,JPO&NCIPI