Patent ID: 8099228

Claim:
A control apparatus for an internal combustion engine, the control apparatus comprising: a variable valve mechanism which makes variable a valve overlap period, in which an intake valve open period overlaps with an exhaust valve open period; overlap period control means for controlling the variable valve mechanism to control the valve overlap period; a turbocharger which includes a turbine driven by exhaust energy of the internal combustion engine, and a variable nozzle for adjusting an flow rate of exhaust gas supplied to the turbine; nozzle opening degree control means for controlling an opening degree of the variable nozzle; pulsation generation request detection means for detecting existence or nonexistence of a request to enhance exhaust pressure pulsation; exhaust volume adjustment means for adjusting an exhaust system volume; and pulsation generation state acquisition means for acquiring a judgment time point at which exhaust pressure pulsation is judged to have been enhanced, or a prediction time point at which exhaust pressure pulsation is predicted to have been enhanced; wherein the nozzle opening degree control means includes nozzle closing control execution means for controlling the opening degree of the variable nozzle to be a first predetermined opening degree, which is on a closing side with respect to the opening degree of the variable nozzle at a detection time point at which a request to enhance exhaust pressure pulsation is detected, for a duration from the detection time point to the judgment time point or the prediction time point; wherein the overlap period control means includes: overlap period limiting means for controlling the valve overlap period to be shorter than the valve overlap period at the detection time point, for the duration from the detection time point to the judgment time point or the prediction time point; and overlap period setting means for setting a valve overlap period so as to overlap with a timing at which a trough of exhaust pressure pulsation comes, after the judgment time point or the prediction time point is passed; and wherein the exhaust volume adjustment means temporarily expands the exhaust system volume over a predetermined time period of which a starting point or an ending point is the starting time point to set a valve overlap period by the overlap period setting means, or a predetermined time period which includes the starting time point of the setting.