| 摘要 |
In an intake-air quantity control apparatus for an internal combustion engine equipped with a variable valve timing system associated with at least an intake valve, a throttle valve located upstream of the intake valve, a throttle actuator variably adjusting a throttle opening of the throttle valve, sensors detecting engine operating conditions, an electronic control unit is connected electrically to the sensors, the variable valve timing system, and the throttle actuator, for automatically controlling an intake-air quantity of air entering the engine depending on the engine operating conditions. The control unit calculates a desired intake-air quantity based on the engine operating conditions, and calculates a threshold limit value that corresponds to a lower limit intake-air quantity above which valve timing control of the intake valve enables the intake-air quantity to be brought closer to the desired intake-air quantity. The control unit calculates a first intake valve timing corresponding to the desired intake-air quantity, and calculates a second intake valve timing substantially corresponding to the threshold limit value. The control units sets a desired valve timing of the intake valve to the second intake valve timing and estimates a desired throttle opening that realizes the desired intake-air quantity by throttle opening control of the throttle valve, when the desired intake-air quantity is below the threshold limit value.
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