| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device for an internal combustion engine capable of accurately estimating oxygen occlusion quantity or the like of a catalyst even if blow-by occurs. <P>SOLUTION: This device stores a detected air-fuel ratio abyfs1 by an upstream air-fuel ratio sensor in an upstream of a first catalyst, a detected air-fuel ratio abyfs2 by a downstream air-fuel ratio sensor in a downstream of the first catalyst, and total fuel injection quantity mfr in an operation cycle every operation cycle, and calculates oxygen occlusion quantity change value ΔO2 (Ncat is a value equivalent to oxygen passing time in the first catalyst, Ncyl is a value equivalent to fuel transportation time from fuel injection to arrival of exhaust gas based on the injected fuel to the upstream air-fuel ratio sensor) based on difference between the upstream air-fuel ratio sensor detected air-fuel ratio Ncat time before abyfs1(i-Ncat) and the current downstream air fuel ratio sensor detected air-fuel ratio abyfs2(i), and the total fuel injection quantity (Ncat+Ncyl) time before mfr(i-Ncat-Ncyl). The oxygen occlusion quantity change valueΔO2 is added every operation cycle to estimate oxygen occlusion quantity OSA of the first catalyst. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
