It is intended to, when abnormality in either one of two rotation detection sections with different detection frequencies occurs, quickly and highly accurately detect the abnormality to favorably deal with abnormality occurring during low engine rotation. It is determined that abnormality is present in the rotation phase detection section, when an absolute value of difference between an actual VTC angle detected by a rotation phase detection section and an integrated value of a VTC change angle detected by motor rotation sensor 201 with the higher detection frequency than the frequency of detection of the actual VTC angle by the rotation phase detection section is equal to or greater than a predetermined value.

A method for controlling valve timing is provided for a turbo engine provided with a continuous variable valve duration (CVVD) device, a two stage variable valve duration device (VVD) and a continuous variable valve timing (CVVT) device. The method includes: classifying control regions; retarding an intake valve closing (IVC) timing and controlling an exhaust valve to limit a valve overlap in a first region; applying a maximum duration to an intake valve and applying a long duration to the exhaust valve in a second region; applying the long duration to the exhaust valve and advancing the IVC timing in a third region; controlling a throttle valve to be fully opened, applying a short duration to the exhaust valve and retarding an exhaust valve opening (EVO) timing in a fourth region; and controlling the throttle valve to be fully, applying the long duration to the exhaust valve and retarding the IVC timing in a fifth region.

A method for controlling continuously variable valve timing (CVVT), may include determining whether a CVVT control is started, detecting a position of a cam and a position of a crankshaft when the CVVT control is started, determining whether the cam is positioned at a locking position based on the positions of the cam and crankshaft, determining whether the cam is controlled to be positioned from the locking position to an advancing position or a holding position, when the cam is positioned at the locking position, and when the cam is controlled to be positioned from the locking position to the advancing position or the holding position and when a condition for performing the CVVT control is satisfied, determining whether a cam torque is negative and performing predetermined CVVT control after waiting a predetermined time when the cam torque is negative.

It is intended to, when abnormality in either one of two rotation detection sections with different detection frequencies occurs, quickly and highly accurately detect the abnormality to favorably deal with abnormality occurring during low engine rotation. It is determined that abnormality is present in the rotation phase detection section, when an absolute value of difference between an actual VTC angle detected by a rotation phase detection section and an integrated value of a VTC change angle detected by motor rotation sensor 201 with the higher detection frequency than the frequency of detection of the actual VTC angle by the rotation phase detection section is equal to or greater than a predetermined value.

A method for diagnosing a variable valve timing system configured for enhancing precision of diagnosis regarding a variable valve timing system by precisely diagnosing whether an oil pressure detecting device of the variable valve timing system normally operates, may include a normal operation time determining operation of determining a normal operation time of an oil pressure detecting device to determine whether the oil pressure detecting device is normal after an engine starts, and a diagnosing operation of diagnosing whether the oil pressure detecting device is normal according to whether the oil pressure detecting device of the VVT system is turned off within the normal operation time or whether oil pressure reaches reference pressure.

A variable valve system including a crank angle sensor that measures a rotation angle of a crankshaft, a cam angle sensor that measures a rotation angle of a camshaft coupled to the crankshaft and which opens and closes valves, and a controller that controls the internal combustion engine. At least one of the crank angle sensor or the cam angle sensor is configured as an absolute angle sensor that measures an absolute rotation angle and outputs a voltage signal corresponding to this rotation angle. The controller is configured to perform a correction operation that corrects a rotation angle value calculated based on the voltage signal.

A method for detecting malfunction of a fastening bolt in a continuous variable valve timing (CVVT) includes: deciding whether a camshaft position sensor is operating normally; learning the most retarded angle position of the camshaft using the camshaft position sensor; deciding whether the learning of the most retarded angle position of the camshaft is normal; and comparing a PWM duty value used in the learning with a set first reference value when the learning of the most retarded angle position of the camshaft is normal.

A system and a method for controlling valve timing of a continuous variable valve duration engine including classifying control regions depending on engine speed and load; applying a maximum duration to an intake valve and a long duration to an exhaust valve and limiting an overlap; applying the maximum duration to the intake valve and the long duration to the exhaust valve, and adjusting the overlap according to the engine load; applying the long duration to the exhaust valve, fixing an exhaust valve open timing and an exhaust valve close timing, and advancing an intake valve close timing according to an increase of engine load; controlling a wide open throttle valve and applying a short duration to the exhaust valve; and controlling a wide open throttle valve, applying the long duration to the exhaust valve, delaying the intake valve close timing according to an increased engine speed.

A method for controlling valve timing of an engine includes: classifying control regions depending on an engine speed and an engine load, and applying a maximum duration to an intake valve and controlling a valve overlap in the first control region; advancing an intake valve closing (IVC) timing and applying the maximum duration to the exhaust valve in the second control region; advancing both the IVC timing and an exhaust valve closing (EVC) timing in the third control region; fixing an exhaust valve opening (EVO) timing and approaching the EVC timing to a top dead center (TDC) in the fourth control region; controlling a wide open throttle valve (WOT) and retarding the EVO timing in the fifth control region; and controlling the WOT, advancing the EVO timing, and approaching the EVC timing to the TDC in the sixth control region.

A valve train device includes a shaft having one or more actuation contours for actuating at least one actuation element of a valve of a combustion engine, and the actuation contours being arranged on the shaft so as to rotate therewith. A sensor unit including one or more sensors is provided, and each of the one or more sensors has a spatial sensing area for sensing a physical variable. In at least one axial position, an actuation contour of the one or more actuation contours is arranged at least partially in the spatial sensing area of a sensor of the one or more sensors.