Control Method of Valve Opening and Closing

A control method for opening and closing an intake valve and an exhaust valve of an engine, the engine including an intake continuous variable valve duration (CVVD) apparatus that is disposed at an intake side of the engine, an intake continuous variable valve timing (CVVT) apparatus disposed at the intake side of the engine, an exhaust CVVD apparatus that is disposed at an exhaust side of the engine, and an exhaust CVVT apparatus disposed at the exhaust side of the engine, the control method comprising:

• determining, by a controller, a driving condition region among a predetermined plurality of driving condition regions that are defined by a speed of the engine and a torque of the engine;
• and
• controlling, by the controller, an opening timing and a closing timing of each of the intake valve and the exhaust valve based on the driving condition region of the engine by controlling of operations of the intake CVVD apparatus, the intake CVVT apparatus, the exhaust CVVD apparatus, and the exhaust CVVT apparatus,
• wherein controlling the opening timing and the closing timing of each of the intake valve and the exhaust valve comprises:
• based on the driving condition region corresponding to a predetermined low torque region, outputting, by the controller, a control signal to provide (i) an intake valve closing (IVC) timing to be before a bottom dead center (BDC) of a stroke of the engine and (ii) an exhaust valve opening (EVO) timing to be before the BDC.