Patent ID: 6502543
Filing Date: 2003-01-07
Classification: F01L,F02B,F02D,Y02T

Abstract:
An intake-air quantity control apparatus for an internal combustion engine comprising: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; and a control unit configured to be 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; said control unit comprising a data processing section programmed to perform the following, calculating a desired intake-air quantity based on the engine operating conditions; calculating a first intake valve timing corresponding to the desired intake-air quantity; determining, responsively to the engine operating conditions, whether the desired intake-air quantity is below 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 of the engine to be brought closer to the desired intake-air quantity; calculating a second intake valve timing substantially corresponding to the threshold limit value; setting a desired valve timing of the intake valve to the second intake valve timing when the desired intake-air quantity is below the threshold limit value; and calculating 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.