| 摘要 |
PROBLEM TO BE SOLVED: To prevent occurrence of flame-out and torque shock at the time of changing-over an excess air ratio. SOLUTION: Demand engine torque Ty is found in accordance with accelerator opening degree, etc., (step 101), and target fuel injection quantity Fuel and a target excess air ratioλ0 are found in accordance with the demand engine torque Ty (step 102). Thereafter, an upper limit value Fmax and a lower limit value Fmin of a fuel injection quantity range in which air-fuel mixture stably burns are found (step 103) in accordance with a range of an excess air ratio at which air fuel mixture stably burns and actual suction air quantity, and when Fuel>Fmax, fuel injection timing IJT is set as timing Thomo for homogeneous combustion (air intake process) (step 104-106) by guard-treating the fuel injection quantity Fuel by the upper limit value Fmax. Additionally, when Fuel< Fmin, the fuel injection timing IJT is set as timing Tstr for stratified combustion Tstr (compression process) (step 107-109) by guard-treating the fuel injection quantity Fuel by the lower limit value Fmin.
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