METHOD FOR CONTROLLING CONTINUOUSLY VARIABLE VALVE TIMING UNIT BY USING ENGINE ROUGHNESS

摘要

PURPOSE: A control method of a continuously variable valve timing unit by using engine roughness is provided to improve fuel efficiency, and to minimize exhaust gas regardless of deviation of the engine by increasing and decreasing overlap of the continuously variable valve timing unit through closed loop control with using the engine roughness. CONSTITUTION: Coolant temperature is compared with the predetermined value(S1), and condition satisfaction for controlling the continuously variable valve timing unit by engine roughness is decided in case of coolant temperature to be over the predetermined value(S2). Engine roughness is compared with the critical value(S3), and the valve overlap is decreased in case of engine roughness to be over the critical value(S4). The valve overlap is compared with the maximum value(S5), and the valve overlap is increased in case of the valve overlap to be less than the maximum valve overlap(S6). The valve overlap is fixed to the maximum valve overlap in case of the valve overlap to be over the maximum valve overlap(S7).