| 摘要 |
PROBLEM TO BE SOLVED: To provide a system for suppressing exhaust of unburnt HC, by increasing an exhaust temperature in cold engine with simple structure, and warming up a catalyst early. SOLUTION: The exhaust temperature can be increased by increasing an amount of fuel for after burning, while ignition timing is set from 5°before the top dead center to 36°after the top dead center to suppress effective torque of a shaft of an engine in a suitable amount. By deflection spray, fuel is carried near a plug without collision of the fuel with a crown face of a piston or a cylinder wall. The fuel injected in a second half of a compression stroke is not diffused to prevent the fuel or air-fuel mixture entering into a quench layer near the cylinder wall and thereby to reduce an unburnt HC amount. At this time, an air-fuel ratio is made to be a stoichiometric air-fuel ratio or in a slight lean state, and the exhaust temperature is kept to be high, so as to make the after burning be likely to occur. When a temperature of the catalyst is sufficiently increased and it is determined that HC and NOx are sufficiently reduced even if normal combustion is performed, the control is returned to a normal control after the warm-up. COPYRIGHT: (C)2005,JPO&NCIPI
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