| 摘要 |
PROBLEM TO BE SOLVED: To achieve both drastic delay of ignition timing and combustion stability, increase the temperature of exhaust gas when an engine is cold and reduce HC emission amount. SOLUTION: At the time of completion of warming up, normal stratified combustion operation and homogeneous combustion operation are performed. When the engine is cold, to promote activation of a catalyst converter and reduction of HC emission amount, in a top dead center injection operation mode, fuel injection is performed astride a top dead center such that injection start timing IT is before the compression top dead center and injection completion timing ITe is after the top dead center. Ignition timing ADV is after the top dead center. At the compression top dead center, swirls and tumbles are damped, minute turbulence is activated, and position change of a piston is small. Therefore, stable combustion can be achieved. When engine speed is transiently reduced during idle operation, the ignition timing ADV is corrected to be advanced and second ignition is added, as indicated in (c). Since the ignition timing ADV approaches the MBT point, torque is increased with good responsiveness without waiting for increase in intake air amount. COPYRIGHT: (C)2007,JPO&INPIT
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