| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide an air-fuel ratio control device capable of improving both of the NOx reduction efficiency and the fuel consumption performance in an engine of the Miller cycle operation. <P>SOLUTION: The air-fuel ratio control device for an engine 100 of the Miller cycle operation, comprising a catalyst 33 with an oxygen storage function includes an acceleration determining means S102 for determining whether or not the vehicle should accelerate based on the acceleration pedal operation amount after the catalyst atmosphere of the catalyst 33 becomes continuously in a state leaner than the stoichiometry, an air-fuel ratio controlling means S103 for rich spike control by adjusting the fuel injection amount of a fuel injection device 25 so as to achieve a target air-fuel ratio set on the rich side rather than the stoichiometry based on the oxygen storage amount of the catalyst 33 at the vehicle acceleration, and a valve timing controlling means S104 for controlling an air inlet valve 7 to an acceleration valve timing by a valve timing changing device 73 at the time of the vehicle acceleration so that the effective compression ratio becomes higher than that at the time of the Miller cycle operation. <P>COPYRIGHT: (C)2009,JPO&INPIT</p> |
