NOx STORAGE QUANTITY ESTIMATING METHOD

摘要

PROBLEM TO BE SOLVED: To provide an NOx storage quantity estimating method for highly accurately estimating an NOx storage quantity, while using a polynomial of always modeling the newest catalyst state.;SOLUTION: This method estimates the NOx storage quantity of an NOx storage catalyst interposed in an exhaust passage of an engine, and comprises a process 12 of estimating the NOx storage quantity by using the polynomial of reflecting an NOx storage characteristic of the NOx storage catalyst. This process comprises a process 18 of successively correcting respective factors of the polynomial by adaptation estimating logic, and changes a value of a weighting factor of a point of not changing a value of the NOx conversion rate in response to a deterioration characteristic of the NOx storage catalyst, even if a catalyst characteristic of the NOx storage catalyst in the adaptation estimating logic changes.;COPYRIGHT: (C)2008,JPO&INPIT