CONTROL DEVICE OF INTERNAL COMBUSTION ENGINE, AND DETERIORATION DIAGNOSIS METHOD OF CATALYST CONVERTER

摘要

PROBLEM TO BE SOLVED: To raise a frequency of the execution of a deterioration diagnosis of a catalyst converter while preventing an erroneous diagnosis.

SOLUTION: This control device of an internal combustion engine comprises: an oxygen consumption amount calculation means M5 which calculates an oxygen consumption amount during a period that an output of an oxygen concentration sensor reaches a prescribed value or larger from a time point at which the supply of fuel is restarted after stopping the supply of the fuel to the internal combustion engine; a center A/F ratio correction means M11 which corrects a center A/F ratio on the basis of the oxygen consumption amount; a relative O2 storage amount calculation means M7 which calculates an oxygen amount supplied to the catalyst converter or consumed from the catalyst converter as a relative O2 storage amount with the corrected center A/F ratio as a reference; an air/fuel ratio control means M8 which alternately operates an air/fuel ratio to a rich side and a lean side with the corrected center A/F ratio as a reference on the basis of the relative O2 storage amount; and a catalyst deterioration determination means M6 which determines that the catalyst converter has been deteriorated when a deterioration determination parameter which is calculated by digitalizing a correlation of outputs of the air/fuel ratio sensor and the oxygen concentration sensor exceeds a reference value.

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