Valve timing control system for internal combustion engine

摘要

A valve timing control system for an internal combustion engine for preventing dispersion of a control amount and unexpected unlocking of a lock pin is provided. The valve timing control system is provided with actuators 15 and 16 connected to cam shafts 15C and 16C, hydraulic pressure supply units 19 and 20 for driving the actuators, and a controller 21A for controlling a hydraulic pressure for the actuators depending on operating states while changing a relative phase of the cam shafts relative to crank shafts. The actuator includes a locking mechanism for setting the relative phase to a lock-up position and unlocking mechanisms for unlocking the locking mechanism in response to a predetermined hydraulic pressure, and the controller restricts a control of valve timing within a predetermined range of said lockup position in the locking mechanism.