Patent ID: 6843226

Claim:
An intake control apparatus for an internal combustion engine comprising: a variable valve operating mechanism configured and arranged to change a valve lift characteristic of a plurality of intake valves; a collector connected to a plurality of intake passages fluidly coupled to a plurality of cylinders of the internal combustion engine; a throttle valve adjustably positioned upstream of the collector to control an amount of air drawn into the collector by changing an opening degree of the throttle valve; and a control unit configured to adjust the opening degree by controlling the throttle valve and to adjust the valve lift characteristic by controlling the variable valve operating mechanism such that an intake air amount drawn into the cylinders reaches a target intake air amount that is set according to operating conditions of the internal combustion engine, the control unit being further configured to adjust the valve lift characteristic by controlling the variable valve operating mechanism to change the intake air amount while maintaining the opening degree of the throttle valve substantially at an opening degree that achieves a first prescribed negative pressure inside the collector when the internal combustion engine is operating in a valve control region including medium loads, the control unit being further configured to control the throttle valve to change the opening degree to achieve a second prescribed negative pressure that is more negative than the first prescribed negative pressure of the valve control region, and to adjust the valve lift characteristic by controlling the variable valve operating mechanism to control the intake air amount so that internal EGR is promoted with the second prescribed negative pressure when the internal combustion engine is operating in an internal EGR priority region including loads lower than the medium loads in the valve control region, the control unit being further configured to adjust the valve lift characteristic of the intake valves by controlling the variable valve operating mechanism and to adjust the pressure inside the collector closer to atmospheric pressure than the second prescribed negative pressure by controlling the opening degree of the throttle valve when the internal combustion engine is operating in the internal EGR priority region and a temperature of the internal combustion engine is lower than a prescribed temperature.