| 摘要 |
PROBLEM TO BE SOLVED: To enhance the reliability of the variable valve-timing control by reducing the rate of occurrence of failed unlocking operation in a locking mechanism of a variable valve-timing device. SOLUTION: Unlocking control is conducted for a locking mechanism of a variable valve timing device, followed by a determination as to whether unlocking is generated correctly, and if it is a no, the failure relief control for a hydraulic control valve is conducted, and the motions to reciprocate the valve element of the control valve in prescribed strokes are repeated (steps 101-103). Thereby the control valve can be restituted to the normally operable condition by the failure relief control in the case the failed operation is of temporary type, for example originating from foreign matters biting into the control valve. Determination is made whether the control valve is in normal operation until the failure relief control is finished (step 104), and if the valve operation is normal, the unlocking control is re-conducted (step 106). If at this time, the locking mechanism is normal, unlocking can be generated by re- conducting the unlocking control. |
