| 摘要 |
PURPOSE:To precisely maintain the storage value of oxygen in ternary catalyst at a predetermined value, and to rapidly converge the mixture to a stoichiometric air-fuel ratio by controlling the fuel injection volume so as to simultaneously converge both difference between an estimated fuel volume and a desired fuel volume, and time integration thereof to zero. CONSTITUTION:Engine cylinder air volume estimating means 31 estimates an air volume in an engine cylinder, desired fuel volume setting means 33 determines a desired air fuel volume so as to obtain a stoichiometric air-fuel ratio in accordance with an air volume estimated by the engine cylinder air volume estimating means 31. Further, fuel volume estimating means estimates a fuel volume which is actually fed into the engine cylinder in accordance with the air volume estimated by the engine cylinder air volume estimating means 31 and an output from an air-fuel ratio sensor located in an engine exhaust system upstream of ternary catalyst. Further, fuel injection volume setting means 35 determines a fuel injection volume so as to simultaneously converge both deviation between the fuel volume estimated by the fuel volume estimating means 32 and a desired fuel volume, and the time integration of the deviation which is a precise variation value of oxygen stored in the ternary catalyst in consideration with an exhaust gas volume, to a zero.
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