| 摘要 |
PROBLEM TO BE SOLVED: To sharply reduce the discharge quantity of unburned HC while securing the stable operation of an engine by nearly fully closing an exhaust control valve, burning the main fuel witch excessive air, and additionally injecting the auxiliary fuel in an expansion stroke or in an exhaust stroke during the operation for reducing the discharge quantity of the unburned HC into the atmosphere. SOLUTION: An exhaust control valve 24 is provided in an exhaust pipe 22 extending from a common exhaust pipe 21 connected with two exhaust manifolds 19, 20 in this four-cylinder diesel engine, and fuels are fed to fuel injection valves 6 provided in individual cylinders via a common rail 27. Whether the discharge quantity of the unburned HC into the atmosphere should be reduced or not is judged during the warmup operation of the engine. If this judgment is YES, the exhaust control valve 24 is nearly fully closed, and the main fuel injected from the fuel injection valves 6 is burned with excessive air. The auxiliary fuel is additionally injected at the predetermined timing in an expansion stroke or in an exhaust stroke, thereby the discharge of the unburned HC is suppressed. |
