Control apparatus for an internal combustion engine

A control apparatus for an internal combustion engine which hydraulically drives a variable mechanism for continuously causing a rotational phase of a camshaft with respect to a crankshaft of the internal combustion engine to be variable by dint of a hydraulic pressure control solenoid valve to change timings for opening/closing at least one of an intake valve and an exhaust valve, the control apparatus comprising:

• a crank angle sensor for detecting a reference rotational position of the crankshaft;
• a cam angle sensor for detecting a reference rotational position of the camshaft;
• means for detecting an actual phase angle of the camshaft based on detection signals from the crank angle sensor and the cam angle sensor;
• means for detecting an operational state of the internal combustion engine;
• means for setting a target phase angle of the camshaft based on an operational state detected by the operational state detecting means;
• and
• means for performing phase angle feedback control calculation so that the actual phase angle coincides with the target phase angle, to calculate an amount of operation for the hydraulic pressure control solenoid valve, wherein:
• the phase angle feedback control calculation is started for a first time after a KEY is turned ON with an initial value of an integral term set to a predetermined value;
• the phase angle feedback control calculation is performed using a control gain obtained by multiplying a control gain at a time of normal control when a control difference is equal to or larger than a preset value during the phase angle feedback control;
• and
• the phase angle feedback control calculation is performed using the control gain at the time of normal control when the control difference is smaller than the preset value during the phase angle feedback control.