CONTROL DEVICE OF INTERNAL COMBUSTION ENGINE

PROBLEM TO BE SOLVED: To provide a control device of an internal combustion engine capable of improving accuracy in controlling an air-fuel ratio by detecting an actual air-fuel ratio with high accuracy by properly calculating a detected air-fuel ratio under consideration of influence of intake air blowing in an overlap period, in a case when an air-fuel ratio sensor is disposed just at a downstream side of a collecting portion of exhaust branch passages.SOLUTION: A detected equivalent ratio KACT is calculated while correcting an instantaneous detected equivalent ratio KACTSTG to a rich direction by performing a weighted averaging calculation of a plurality of instantaneous detected equivalent ratios KACTSTG, as in a case of existence of a time when an overlap period in which an intake valve and an exhaust valve are simultaneously opened, the detected equivalent ratio is shifted to a lean side with respect to an actual (true) air-fuel ratio when the detected equivalent ratio KACT is calculated by simply averaging the instantaneous detected equivalent ratio KACTSTG obtained by sampling an output of an air-fuel ratio sensor by every certain crank angle.SELECTED DRAWING: Figure 5 【課題】 空燃比センサが排気分岐通路の集合部の直ぐ下流側に配置される場合に、オーバラップ期間において吹き抜ける吸気の影響を考慮した検出空燃比の算出をより適切に行うことによって、実際の空燃比を高い精度で検出し、空燃比制御の精度を向上させることができる内燃機関の制御装置を提供する。【解決手段】吸気弁と排気弁が共に開弁するオーバラップ期間がある場合には、一定クランク角度毎に空燃比センサ出力をサンプリングすることによって得られる瞬時検出当量比ＫＡＣＴＳＴＧを単純に平均化して検出当量比ＫＡＣＴを算出すると、検出当量比ＫＡＣＴが実際の（真の）空燃比よりリーン側にずれるので、複数の瞬時検出当量比ＫＡＣＴＳＴＧの重み付け平均化演算を行うことにより、瞬時検出当量比ＫＡＣＴＳＴＧをリッチ方向へ補正して検出当量比ＫＡＣＴを算出する。【選択図】 図５