| 摘要 |
PROBLEM TO BE SOLVED: To promptly detect an abnormal condition such that a lock pin is not normally projected, in a variable valve timing apparatus with an intermediate lock mechanism.SOLUTION: If a lock request occurs in a period before learning of a reference phase (for example intermediate lock phase) is completed, a change amount in a VCT phase (valve timing) is monitored, and it is determined that the VCT phase has passed through the intermediate lock phase when the change amount in the VCT phase becomes greater than a "determination value". Here, the "determination value" is set to a value greater than a design value of a phase difference between the most retarded phase (or most advanced phase) and the intermediate lock phase by a range of a product variation of the phase difference or greater. Consequently, it is accurately determined whether the VCT phase has passed through the intermediate lock phase during lock control, by determining whether the change amount in the VCT phase becomes greater than the "determination value", and the abnormal condition such that the lock pin 58 is not normally projected can be detected promptly. |
