| 摘要 |
PROBLEM TO BE SOLVED: To prevent an unstable state of a control and implement good drivability, even if a feedback control is executed at the time of transition in a fuel priority type engine. SOLUTION: In an actual equivalent ratio calculation means 19 in cylinders, an actual equivalent ratio in cylinders FAIcl is calculated based on an absorbed air amount in cylinders and an inflow fuel injection amount in the cylinders. In a control deviation calculation means 21, control deviation e of which target equivalent ratio is the actual equivalent ratio in cylinders FAIcl is calculated from a difference between the actual equivalent ratio in cylinders FAIcl and an exhaust equivalent ratio FAIex that is calculated based on an exhaust air- fuel ratio obtained by an air-fuel ratio sensor 6. In a controller 22, feedback control of a fuel injection amount of an injector 4 is executed so that the control deviation e converges at zero. Since the control deviation e is calculated from the difference between the actual equivalent ratio in cylinders FAIcl and an exhaust equivalent ratio FAIex, the air-fuel ratio feedback control can be executed in a good follow-up property at the time of transition.
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