| 摘要 |
PROBLEM TO BE SOLVED: To obtain high NOx conversion rate without excessive temperature rise when the exhaust air fuel ratio is made rich to eliminate NOx trapped in an NOx trap catalyst for purification. SOLUTION: A first combustion system (separate retard combustion) is selected when the carrier temperature of catalyst is low, during low speed rotation and in low-load. In the first combustion system, main combustion for generating main torque and at least one time preliminary combustion prior to the main combustion are performed. The fuel injection to an engine is controlled so that at least one preliminary combustion is caused near the top dead center of compression and the main combustion is started after the end of the preliminary combustion. A second combustion system (ordinary combustion) in which the exhaust temperature rise effect is smaller than that in the first combustion system is seleted when the carrier temperature of catalyst is high, during high speed rotation and in high-load. COPYRIGHT: (C)2005,JPO&NCIPI
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