| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent worsening of a temporary exhaust state due to discharge of oxygen from a catalyst a worsening of a total fuel cost being suppressed when a whole of an operation region is observed, in a direct injection type engine 1 provided with catalysts 32 and 33 to provide a three-dimensional purifying function in the vicinity of at least a theoretical air-fuel ratio and switched into a stratified combustion state on the low rotation low load side and an uniform combustion state on the high rotation or high load side and brought into an uniform combustion state throughout the whole of an operation region under a non-worming state. SOLUTION: When an engine 1 is brought into a non-warming state and in a state that it is difficult for the engine to be brought into a stratified combustion state, a second operation mode is selected (S2, S3→S6). A target value of an air-fuel ratio feedback control in a coldλ=1 region forms a theoretical air-fuel ratio. During a normal operation period after warming of the engine, a first operation mode is selected (S2, S3→S4). A target value of an air fuel ratio feedback control in warmλ=1 region is set to a value slightly nearer to the rich side than that of a theoretical air-fuel ratio.</p> |
