| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent an air-fuel ratio from staying in an exhaust gas deterioration air-fuel ratio region in changing between a lean combustion mode and a stoichiometric combustion mode and to prevent a torque step. Ž<P>SOLUTION: The change from the lean combustion mode to the stoichiometric combustion mode is required when a requested torque reaches a specific change torque T0 and a throttle valve 10 opening is controlled to A1 as a target. The amount of fresh air flowing into an actual cylinder changes with a response delay followed(the solid line A2). In accordance with the change (the solid line A2) of the actual fresh air amount, compressed air is directly supplied (the solid line E) into a cylinder so that the air-fuel ratio in the lean combustion mode is maintained (the solid line D2). A fuel injection quantity and ignition timing show characteristics satisfying the solid line B2 and the solid line C2, respectively. When the amount of fresh air (the solid line A2) flowing into the cylinder through an intake valve 8 is reduced (the time t2) to a requested fresh air amount in the stoichiometric combustion mode after the change, the supply of compressed air is stopped and the mode is completely changed to the stoichiometric combustion mode. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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