| 摘要 |
PROBLEM TO BE SOLVED: To prevent the deterioration in combustion stability caused when a valve lift changes at low vehicle speed time such as an idle state in an internal combustion engine having a variable valve lift mechanism. SOLUTION: When a vehicle speed SP is low, a target shaft position Lt is restricted by processing of Steps S160, S180, S190. Thus, since the valve lift of an intake valve does not largely changes even if a throttle valve opens, even if throttle opening rapidly reduces thereafter, a change is not wholly required in the valve lift, and even if there is a change, it is only a little change. Thus, a large change in the valve lift by the variable valve lift mechanism is not performed to thereby prevent temporary generation of an improper valve lift such as an excessive valve overlap quantity caused by response delay in the intake valve. Thus, when the vehicle speed SP is low, even if the throttle valve is rapidly closed, the combution stability of an engine can be maintained.
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