Patent ID: 8965662
Filing Date: 2015-02-24
Classification: F02D

Abstract:
1. An abnormality determining apparatus comprising: an air-fuel ratio controller configured to control an air-fuel mixture air-fuel ratio which is an air-fuel ratio of an air-fuel mixture of an internal combustion engine to be selectively either one of an output change period parameter calculator configured to calculate, after the air-fuel ratio controller performs at least one of first switching of the air-fuel mixture air-fuel ratio from the predetermined rich air-fuel ratio to the predetermined lean air-fuel ratio and second switching of the air-fuel mixture air-fuel ratio from the predetermined lean air-fuel ratio to the predetermined rich air-fuel ratio, an output change period parameter representing a period from a timing at which an amount of change of output of an air-fuel ratio sensor reaches a predetermined amount of change to a timing at which the amount of change of output of the air-fuel ratio sensor returns to the predetermined amount of change, the output of the air-fuel ratio sensor being to change due to at least one of the first switching and the second switching, the air-fuel ratio sensor being disposed in an exhaust gas passage of the internal combustion engine to detect an exhaust gas air-fuel ratio which is an air-fuel ratio of exhaust gas from the internal combustion engine; an output change amount extremum calculator configured to calculate an output change amount extremum obtained within the period represented by the output change period parameter calculated by the output change period parameter calculator, the output change amount extremum including an extremum of the amount of change of output of the air-fuel ratio sensor; and an abnormality determining device configured to determine an abnormality of the air-fuel ratio sensor based on a relationship between the output change period parameter and the output change amount extremum.