Patent ID: 8033097

Claim:
An exhaust control device for an internal combustion engine, comprising: a NOx purifying catalyst disposed in an exhaust system; and a rich control means for calculating a fuel injection amount based on a difference between a target exhaust air fuel ratio and an actual exhaust air fuel ratio to feedback-control the actual exhaust air fuel ratio so that a reducing atmosphere is created in the exhaust system to thereby reduce NOx trapped by the NOx purifying catalyst, wherein the rich control means includes a learning means for calculating and updating a control correction value of the fuel injection amount based on an actual control value of the fuel injection amount during the feedback control, wherein the fuel injection amount is calculated during the feedback control by using the control correction value, wherein the rich control means has a combustion rich mode for controlling an amount of main fuel injection and a post rich mode for controlling an amount of post fuel injection that is conducted after combustion, wherein the learning means comprises a control correction value storing means for storing the control correction value for each of the combustion rich mode and the post rich mode.