| 摘要 |
PROBLEM TO BE SOLVED: To provide an internal combustion engine exhaust emission control system capable of executing a purge control while suppressing degradation in the exhaust emission control system.SOLUTION: An internal combustion engine exhaust emission control system comprises: an oxidation catalyst provided in an exhaust passage of an internal combustion engine; purification means provided downstream of the oxidation catalyst; and purge control execution means increasing a temperature of exhaust gas passing through the oxidation catalyst by supplying a reducer to the oxidation catalyst and executing a purge control over the purification means. In a case of executing the purge control, the reducer is supplied to the oxidation catalyst after the oxidation catalyst is in an active range. If a detected temperature at an outlet of the oxidation catalyst does not reach a temperature at which the purification means can be regenerated, supply lapsed time of the reducer passes to be equal to or longer than time necessary to increase the temperature at which the purification means can be regenerated, and an exhaust temperature at an inlet of the purification means is increased to be equal to or higher than a temperature at which the purification means is possibly degraded, then the supply of the reducer is stopped after passage of time necessary for the purge control. |
