Patent Document ID: 20140090627
Application ID: 14113300
Patent Flag: 0

Claim One:
1. A control device for internal combustion engine, the control device comprising: an air-fuel ratio detection means for detecting an air-fuel ratio of mixture gas generated in a combustion chamber; and an exhaust recirculation device introducing an exhaust gas into an intake passage, the exhaust gas being discharged from the combustion chamber to an exhaust passage, the control device being configured to: calculate an estimated air-fuel ratio of the mixture gas generated in the combustion chamber, the estimated air-fuel ratio being an estimated value of the air-fuel ratio; set a target amount of the recirculated exhaust gas so as to control a detected air-fuel ratio to match the estimated air-fuel ratio, the detected air-fuel ratio being an air-fuel ratio detected by the air-fuel detection means, the target amount being a target value of an amount of the exhaust gas introduced into the intake passage by the exhaust recirculation device; and perform an exhaust recirculation control for controlling an operation condition of the exhaust recirculation device so as to allow the exhaust gas having the target amount of the recirculated exhaust gas to be introduced into the intake passage by the exhaust recirculation device, the control device being configured to: have a function to calculate an instant correction value, the instant correction value being a correction value for correcting a current target amount of the recirculated exhaust gas so as to control an air-fuel ratio deviation to be zero, the air-fuel ratio deviation being a deviation of the detected air-fuel ratio in reference to the estimated air-fuel ratio; have a learning function to calculate a learned correction value and memorize the learned correction value, the learned correction value being an accumulated value of the instant correction values calculated successively; perform a correction to a relationship for base amount of the recirculated exhaust gas so as to allow the engine to perform with an expected property regardless of the deviation of the detected air-fuel ratio in reference to the estimated air-fuel ratio, the relationship being a relationship between a parameter for setting base amount of the recirculated exhaust gas and a base amount of the recirculated exhaust gas, the parameter being a predetermined parameter relating to the engine, the base amount being a base value regarding the target amount of the recirculated exhaust gas, the relationship being defined in advance; and set the base amount of the recirculated exhaust gas from the corrected relationship for base amount of the recirculated exhaust gas based on the parameter for setting base amount of the recirculated exhaust gas, the parameter having been corrected by the instant correction value and the learned correction value, followed by employing the set base amount of the recirculated exhaust gas as the target amount of the recirculated exhaust gas; or correct the base amount of the recirculated exhaust gas by the instant correction value and the learned correction value, the base amount having been set from the corrected relationship for base amount of the recirculated exhaust gas based on the parameter for setting base amount of the recirculated exhaust gas, followed by employing the corrected base amount of the recirculated exhaust gas as the target amount of the recirculated exhaust gas, wherein the control device being configured to forbid the performance of the learning function upon a sign of a ratio of a change amount of an actual target amount of the recirculated exhaust gas in reference to a change amount of the parameter for setting base amount of the recirculated exhaust gas being different from a sign of a ratio of a change amount of a referential target amount of the recirculated exhaust gas in reference to the change amount of the parameter for setting base amount of the recirculated exhaust gas, in the case of: the relationship for base amount of the recirculated exhaust gas before the correction to the relationship for base amount of the recirculated exhaust gas being referred to as a non-corrected relationship for base amount of the recirculated exhaust gas; the relationship for base amount of the recirculated exhaust gas after the correction to the relationship for base amount of the recirculated exhaust gas being referred to as a corrected relationship for base amount of the recirculated exhaust gas; the following target amount of the recirculated exhaust gas being referred to as the referential target amount of the recirculated exhaust gas: the target amount of the recirculated exhaust gas set based on the base amount of the recirculated exhaust gas set from the non-corrected relationship for base amount of the recirculated exhaust gas based on the parameter for setting target amount of the recirculated exhaust gas, the parameter having been corrected by the instant correction value and the learned correction value; or the target amount of the recirculated exhaust gas set based on the base amount of the recirculated exhaust gas obtained by correcting the base amount of the recirculated exhaust gas by the instant correction value and the learned correction value, the base amount having been set from the non-corrected relationship for base amount of the recirculated exhaust gas based on the parameter for setting base amount of the recirculated exhaust gas; and the following target amount of the recirculated exhaust gas being referred to as the actual target amount of the recirculated exhaust gas: the target amount of the recirculated exhaust gas set based on the base amount of the recirculated exhaust gas from the corrected relationship for base amount of the recirculated exhaust gas based on the parameter for setting target amount of the recirculated exhaust gas, the parameter having been corrected by the instant correction value and the learned correction value; or the target amount of the recirculated exhaust gas set based on the base amount of the recirculated exhaust gas obtained by correcting the base amount of the recirculated exhaust gas by the instant correction value and the learned correction value, the base amount having been set from the corrected relationship for base amount of the recirculated exhaust gas based on the parameter for setting base amount of the recirculated exhaust gas.