Control device for internal combustion engine

Abstract

A control device for an internal combustion engine provided by the present invention is a control device which can satisfy both a requirement relating to exhaust gas performance of the internal combustion engine and a requirement relating to operation performance by properly regulating a change speed of a required air-fuel ratio, in the internal combustion engine which uses torque and an air-fuel ratio as control variables. The control device receives the requirement relating to the exhaust gas performance of the internal combustion engine, and calculates an air-fuel ratio which satisfies the requirement as a required air-fuel ratio. When a predetermined reduction condition is not satisfied, an original required air-fuel ratio is directly determined as a final required air-fuel ratio. However, when the reduction condition is satisfied, the change speed is reduced by processing the signal of the original required air-fuel ratio, and determines the required air-fuel ratio with the change speed reduced as the final required air-fuel ration. The reduction condition includes a condition that the change amount of the original required air-fuel ratio, in more detail, a change amount per calculation period is larger than a predetermined air-fuel ratio change determination value.