| 摘要 |
PROBLEM TO BE SOLVED: To fix a VVT actuator at most stable position by estimating the driving force of a valve timing variable mechanism (VVT) actuator according to supply oil pressure, and controlling the opening and closing timing of an intake and exhaust valve when the estimated value is below the valve timing variable control limit boundary value. SOLUTION: A variable control limit means learns the driving force (ACT driving force) of a VVT actuator which satisfies a designated response time as a valve timing variable control limit boundary value (VVT control limit boundary value) FL during valve timing variable control. The VVT control limit boundary value FL is updated according to the actual spark-advance amount (actual spark-advance amount)θa to a valve timing variable control spark-advance command, and the updated amount is determined by the time change rate of the actual spark-advance amountθa. When the ACT driving force is remarkably lowered, that is, even in the case of below the VVT control limit boundary value, the control of the valve timing control means is limited so that the VVT actuator is fixed in a most stable position so as to stabilize the operating condition.
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