EGR ESTIMATION DEVICE FOR INTERNAL COMBUSTION ENGINE AND EGR ESTIMATION METHOD FOR INTERNAL COMBUSTION ENGINE

PROBLEM TO BE SOLVED: To provide an EGR estimation device for an internal combustion engine and an EGR estimation method for the internal combustion engine capable of estimating an EGR rate by using an intake oxygen concentration sensor while absorbing effects of a deterioration degree and an individual difference.SOLUTION: An estimation device 100 includes an internal combustion engine 1, an intake passage 11, an exhaust passage 21, a supercharger 30, an EGR device 40, an intake oxygen concentration sensor 16 and a controller 80. When the operating state of the internal combustion engine 1 is in a first operating region, the controller 80 acquires output from the intake oxygen concentration sensor 16. When the operating state of the internal combustion engine 1 is in a second operating region, the acquired output from the intake oxygen concentration sensor 16 is used as a reference, and an EGR rate α is estimated based on the output from the intake oxygen concentration sensor 16.SELECTED DRAWING: Figure 1 【課題】劣化度合いや個体差の影響を吸収しつつ、吸気酸素濃度センサでＥＧＲ率を推定することが可能な内燃機関のＥＧＲ推定装置及び内燃機関のＥＧＲ推定方法を提供する。【解決手段】推定装置１００は、内燃機関１と、吸気通路１１と、排気通路２１と、過給機３０と、ＥＧＲ装置４０と、吸気酸素濃度センサ１６と、コントローラ８０と、を備える。コントローラ８０は、内燃機関１の運転状態が第１の運転領域にある場合に、吸気酸素濃度センサ１６の出力を取得する。また、内燃機関１の運転状態が第２の運転領域にある場合に、取得した吸気酸素濃度センサ１６の出力を基準として、吸気酸素濃度センサ１６の出力に基づきＥＧＲ率αを推定する。【選択図】図１