Patent Document ID: 9664096
Application ID: 14831191
Patent Flag: 1

Claim One:
1. A control apparatus for an internal combustion engine, the control apparatus comprising: a plurality of cylinders; fuel injection valves configured to inject fuel to each of the plurality of cylinders; a catalyst that is provided in an exhaust passage, the catalyst being configured to purify gas that is emitted from the internal combustion engine; an upstream-side sensor that is arranged upstream of the catalyst, the upstream-side sensor being configured to output an output value corresponding to an actual air-fuel ratio of gas that is emitted from the internal combustion engine; a downstream-side sensor that is arranged downstream of the catalyst, the downstream-side sensor being configured to output an output value corresponding to an actual air-fuel ratio of gas that is emitted from the catalyst; and an electronic control unit configured to: (i) execute air-fuel ratio control including main feedback correction and sub-feedback correction, the main feedback correction being correction for a fuel injection amount that is injected from the fuel injection valves such that the output value of the upstream-side sensor becomes an output value corresponding to a target air-fuel ratio, the sub-feedback correction being correction for the fuel injection amount that is corrected through the main feedback correction such that the output value of the downstream-side sensor becomes an output value corresponding to the target air-fuel ratio, the sub-feedback correction including a calculation of a sub-correction value including a learning value that compensates for a steady deviation between the output value of the downstream-side sensor and the output value corresponding to the target air-fuel ratio, (ii) when there are cylinder-to-cylinder variations in the fuel injection amount that is injected from the fuel injection valves, execute a process of correcting the fuel injection amount that is corrected in the air-fuel ratio control, (iii) each time the electronic control unit determines that a degree of the cylinder-to-cylinder variations is lower than or equal to a normal determination value, store the learning value at that point in time as a normal value, and (iv) when the degree of the cylinder-to-cylinder variations is higher than or equal to an abnormal determination value, change the learning value at that point in time to the normal value, the abnormal determination value being greater than the normal determination value.