| 摘要 |
PROBLEM TO BE SOLVED: To perform sure emission control of the unburned gas component, and to lower the power consumption of the catalyst for heater by providing an absorbing and removing means in a plurality of exhaust passages connected to a multistage internal combustion engine, and making the timing of the arrival of the unburned gas component removed from each absorbing and removing means to the exhaust emission control catalyst coincide with each other. SOLUTION: During the operation of an engine, an ECU 15 corrects the fuel quantity to be injected into each cylinder of cylinder groups 1a, 1b, and performs the feedback control so that the air-fuel ratio of the exhaust gas coincides with the theoretical air-fuel ratio. At the time of cold starting of an internal combustion engine 1, in the case where temperature of way catalysts 7, 8 are less then the predetermined temperature, the exhaust gas from the engine 1 is flowed into each of the three way catalysts 7, 8 so as to absorb the unburned gas component in the exhaust gas. Continuously, the exhaust gas is let flowed into a three way catalyst 9 inside of a joint exhaust passage. thereafter, when temperature of each of the three way catalysts 7, 8 is raised by the exhaust gas, exhaust temperature or the like is controlled so that the timing of the arrival of the unburned gas removed from each of the three way catalysts 7, 8 to the three way catalyst 9 coincide with the predetermined timing.
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