Patent Document ID: 9644572
Application ID: 14113300
Patent Flag: 1

Claim One:
1. A control device for an internal combustion engine, comprising: at least one combustion chamber; an intake passage connected to the at least one combustion chamber; an exhaust passage connected to the at least one combustion chamber; an air-fuel ratio sensor provided in the exhaust passage for detecting an air-fuel ratio corresponding to an air-fuel ratio of mixture gas generated in the at least one combustion chamber; an EGR device having an EGR passage for recirculating exhaust gas to the intake passage, wherein the exhaust gas is discharged from the at least one combustion chamber to the exhaust passage, a relationship between (a) a predetermined parameter relating to an engine operation and (b) a base EGR amount corresponding to a base value of a target value of an amount of exhaust gas recirculated to the intake passage via the EGR passage being defined as a base relationship in advance; and an electronic control unit programmed to: (A) calculate an estimated air-fuel ratio corresponding to an estimated value of the air-fuel ratio of the mixture gas; (B) calculate an instant correction value corresponding to a correction value for correcting one of (a) the predetermined parameter and (b) the base EGR amount, such that an air-fuel ratio deviation corresponding to a deviation of the detected air-fuel ratio in reference to the estimated air-fuel ratio becomes zero; (C) perform a correction value learning to calculate a learned correction value corresponding to an accumulated value of the instant correction values calculated successively and memorize the learned correction value; (D) perform a base relationship correction to correct the base relationship regardless of the air-fuel ratio deviation to acquire a corrected base relationship so as to allow the engine to operate with an expected property; (E1) perform a correction of the predetermined parameter by the instant correction value and the learned correction value to acquire a corrected parameter, acquire the base EGR amount by applying the corrected parameter to the corrected base relationship and set the acquired base EGR amount as a target EGR amount; or (E2) acquire the base EGR amount by applying, to the corrected base relationship, a non-corrected parameter corresponding to the predetermined parameter which is not corrected by the instant and learned correction values and set, as the target EGR amount, a value acquired by correcting the base EGR amount by the instant and learned correction values; (F) perform an EGR control for controlling an operation state of a valve of the EGR device such that the target EGR amount of exhaust gas is recirculated to the intake passage via the EGR passage; (G) acquire a referential target amount corresponding to one of (a) the base EGR amount acquired by applying the corrected parameter to a non-corrected base relationship corresponding to the base relationship which is not corrected by the base relationship correction and (b) a value acquired by correcting the base EGR amount, which is acquired by applying the non-corrected parameter to the non-corrected base relationship, by the instant and learned correction values; (H) acquire an actual target amount corresponding to one of (a) the base EGR amount acquired by applying the corrected parameter to the corrected base relationship and (b) a value acquired by correcting the base EGR amount, which is acquired by applying the non-corrected parameter to the corrected base relationship, by the instant and learned correction values; and (I) forbid the performance of the correction value learning when a sign of a first ratio corresponding to a ratio of a change amount of the actual target EGR amount in reference to a change amount of the non-corrected parameter is different from a sign of a second ratio corresponding to a ratio of a change amount of the referential target EGR amount in reference to a change amount of the non-corrected parameter.