To restrain filter temperature from dropping when the operation condition of an internal combustion engine is in a transitional state during a filter-regeneration control in an exhaust emission control system of the internal combustion engine provided with a filter in the exhaust passage in order to collect PM in the exhaust gas.
In the filter regeneration control, filter temperature is raised to a command temperature by supplying unburned fuel to a catalyst having function of oxidation. If the engine operation condition is in a transitional state in the filter-regeneration control, the amount of unburned fuel to be supplied to the catalyst is corrected to be increased more than a reference supply amount. In this case, if the engine operation condition is in a transitional state to raise the engine-load, the amount of increase correction of unburned fuel is determined on the basis of the rate of increase in the intake air-flow of the engine (S105, S106). If the engine operation condition is in a transitional state in which the engine-load is reduced, the amount of increase correction of the unburned fuel is determined on the basis of temperature of the catalyst (S110, S111).
WATANABE TADASHI
Hidemi Matsukura
Mayuko Wakuda
Kazunobu Sera
Tsutomu Toyama
Next Patent: STARTER OF ENGINE