VALVE OVERLAP CONTROL METHOD OF INITIAL STAGE OF ENGINE STAGING IN RELATION TO METHOD FOR CONTROLLING VALVE OVERLAP TO REDUCE EXHAUST GAS PRODUCED IN INITIAL STAGE OF ENGINE

摘要

PURPOSE: A valve overlap control method of the initial stage of engine starting is provided to effectively reduce exhaust gas produced in the initial stage of the engine starting by controlling the valve overlap at the initial stage of the engine starting in the real time. CONSTITUTION: A valve overlap control method of the initial stage of engine starting comprises steps of determining the starting state of an engine on the basis of a sensing signal of a starting sensing switch(S1); determining whether exhaust gas flows backward to a surge tank on the basis of a sensing signal of an intake manifold-absolute pressure sensor if the engine is started(S2); gradually increasing a valve overlap angle by operating an actuator if the exhaust gas does not flow backward to the surge tank(S3); determining whether the exhaust gas flows backward to the part between the surge tank and an air cleaner on the sensing signal of the intake manifold-absolute pressure sensor and a sensing signal of a mass air flow sensor if the exhaust gas flows backward to the surge tank(S4); gradually decreasing the valve overlap angle by operating the actuator(S5); determining whether predetermined time has passes after starting the engine through a timer(S6); maintaining an initial setting value of the valve overlap(S7); and determining whether the exhaust gas flows backward to the air cleaner on the basis of the sensing signal of the intake manifold-absolute pressure sensor and the sensing signal of the mass air flow sensor(S8).