To provide an exhaust emission control system capable of efficiently purifying an exhaust emission from immediately after the start of an engine, while precisely controlling an exhaust emission flowing passage, and a method thereof.
The exhaust emission control system includes a main catalyst provided in a main passage, a bypass passage branching once from the main passage located in an upstream of the main catalyst to again join to the main passage in the upstream of the main catalyst, a bypass passage catalyst provided in the bypass passage, a flow control valve which is provided in the main passage and specifically on more downstream side than a portion where the bypass passage branches and more upstream side than a portion where the bypass passage l joins the main passage and can regulate the exhaust emission volume flowing through the main passage. Further, the exhaust emission control system includes a gas temperature estimating means (steps S2, S3, S5) for estimating exhaust emission temperature based on an engine operational status, and a valve control means (steps S8, S9) for performing opening and closing control of the flow control valve based on the estimated exhaust emission temperature.
| JPH11148340A | 1999-06-02 | |||
| JPH09317449A | 1997-12-09 | |||
| JPH0988687A | 1997-03-31 | |||
| JPH08177463A | 1996-07-09 | |||
| JPH07189668A | 1995-07-28 | |||
| JPH07189656A | 1995-07-28 | |||
| JPH06200747A | 1994-07-19 | |||
| JPH05156933A | 1993-06-22 |
Masahiro Fujii
Masaaki Iida
Yasunari Mita