Method for controlling of valve timing of continuous variable valve duration engine

A system for controlling valve timing of a continuous variable valve duration engine provided with a turbo charger, the system comprising:

• a data detector configured to detect data related to a running state of a vehicle;
• a camshaft position sensor configured to detect a position of a camshaft;
• an intake continuous variable valve duration (CVVD) device configured to control an opening time of an intake valve of an engine;
• an exhaust two stage variable valve duration (VVD) device configured to control an opening time of an exhaust valve of the engine by two different durations;
• an exhaust continuously variable valve timing (CVVT) device configured to control an opening and closing timing of the exhaust valve of the engine;
• and
• a controller configured to classify a plurality of control regions depending on an engine speed and an engine load based on signals from the data detector and camshaft position sensor, and configured to control the intake CVVD device, the exhaust two stage VVD device and the exhaust CVVT device according to the control regions,
• wherein the plurality of control regions includes:
• a first control region determined by the controller when the engine load is less than a first predetermined load,
• a second control region determined by the controller when the engine load is greater than or equal to the first predetermined load and less than a second predetermined load,
• a third control region determined by the controller when the engine load is greater than or equal to the second predetermined load and less than a third predetermined load,
• a fourth control region determined by the controller when the engine load is greater than or equal to the second predetermined load and the engine speed is greater than or equal to a first predetermined speed and less than a second predetermined speed, and
• a fifth control region determined by the controller when the engine load is greater than or equal to the third predetermined load and the engine speed is less than the first predetermined speed, and
• wherein the controller retards an intake valve closing (IVC) timing by a predetermined angle and controls the exhaust valve to limit a valve overlap by applying a long duration in the first control region, applies a maximum duration to the intake valve and applies the long duration to the exhaust valve to maintain the valve overlap as a maximum value in the second control region, applies the long duration to the exhaust valve and advances the IVC timing according to an increase of the engine load in the third control region, controls a throttle valve to be fully opened and applies a short duration to the exhaust valve and retards an exhaust valve opening (EVO) timing by a predetermined angle in the fourth control region, and controls the throttle valve to be fully opened and applies the long duration to the exhaust valve and retards the IVC timing according to an increase of the engine speed in the fifth control region.