CONTROL METHOD OF INTERNAL COMBUSTION ENGINE AND CONTROL DEVICE OF INTERNAL COMBUSTION ENGINE

PROBLEM TO BE SOLVED: To provide a control method of an internal combustion engine which can sufficiently utilize the performance of a turbocharger by making compatible both the improvement of the responsiveness of supercharging, and the prevention of an overshoot of a turbine fore-and-aft pressure ratio, and can further safely use the proper-sized turbocharger, and a control device of the internal combustion engine.SOLUTION: A control method of an internal combustion engine has: a turbine fore-and-aft pressure ratio calculation step for acquiring a ratio of turbine upstream-side synchronized pressure which is obtained by adding turbine upstream-side exhaust pressure with respect to turbine downstream-side synchronized pressure which is obtained by adding turbine downstream-side exhaust pressure and atmospheric pressure, and the atmospheric pressure; a turbine fore-and-aft pressure ratio rise rate calculation step for acquiring a pressure ratio rise rate being a rise ratio of the turbine fore-and-aft pressure ratio; a turbine fore-and-aft pressure ratio prediction step for predicting whether or not the turbine fore-and-aft pressure ratio exceeds a preset pressure ratio allowable maximum value; and a turbine fore-and-aft pressure ratio forcible lowering step for controlling a variable nozzle to a side at which a flow speed of an exhaust gas introduced to a turbine is lowered when predicting that the turbine fore-and-aft pressure ratio exceeds the pressure ratio allowable maximum value.SELECTED DRAWING: Figure 3 【課題】過給の応答性の向上とタービン前後圧力比のオーバーシュートの防止とを両立してターボ過給機の性能を充分に利用することが可能であり、適切なサイズのターボ過給機をより安全に使用することができる、内燃機関の制御方法及び内燃機関の制御装置を提供する。【解決手段】タービン下流排気圧力と大気圧とを加算したタービン下流合成圧力に対するタービン上流排気圧力と大気圧とを加算したタービン上流合成圧力の比を求めるタービン前後圧力比算出ステップと、タービン前後圧力比の上昇割合である圧力比上昇率を求めるタービン前後圧力比上昇率算出ステップと、タービン前後圧力比が予め設定された圧力比許容最大値を超えるか否かを予測するタービン前後圧力比予測ステップと、圧力比許容最大値を超えると予測した場合は、タービンへ導く排気ガスの流速を低下させる側に可変ノズルを制御する、タービン前後圧力比強制低下ステップと、を有する。【選択図】図３