| 摘要 |
PROBLEM TO BE SOLVED: To satisfactorily recover the function of exhaust emission controlling catalyst as an internal combustion engine is operated by estimating the adhesion quantity of a purifying performance deteriorating material adhered to the exhaust emission purifying catalyst, and executing the flow velocity control of exhaust gas when the estimated adhesion quantity reaches a prescribed adhesion quantity to raise the temperature of the exhaust emission controlling catalyst. SOLUTION: An exhaust emission controlling catalyst 13 is set in the exhaust pipe 14 of an engine body 1, and it is formed of a NOx adsorbent catalyst 13a and a catalytic converter rhodium 13b. According to the adhesion of a deposit other than NOx to the NOx adsorbent catalyst 13a, an ECU 23 reads the traveling distance of a vehicle from a distance meter 25 and estimates the quantity of the deposit. When the traveling distance is a prescribed value or more, it is judged whether the operating state of the engine 1 is suitable to refresh operation or not on the basis of the detection signal from a crank angle sensor 18. When the suitability to refresh operation is consequently judged, the ignition timing of the engine body 1 is delayed, and the temperature of the exhaust gas is raised to raise the temperature of the NOx adsorbent catalyst 13a. |
