| abstract |
Problem of the invention is, in possessing oxidation catalyst and being configured in the emission control system of the internal combustion engine of the SCR catalyst compared with oxidation catalyst downstream, NO when improving SCR catalyst in unactivated state X Purifying rate.In order to solve the problem, the present invention uses such a way, i.e., in the gas extraction system of the internal combustion engine for supplying the feedway of unburned fuel to oxidation catalyst in the oxidation catalyst in possessing the exhaust passage for being configured in internal combustion engine, the SCR catalyst being configured in the exhaust passage compared with oxidation catalyst downstream and when SCR catalyst is unactivated, by reducing the quantity delivered of unburned fuel when internal combustion engine carries out underrun, so that flowing to the NO of SCR catalyst 2 Amount increase. |