Vane-type variable valve timing control apparatus and control method

A vane type variable valve timing control apparatus for changing a rotation phase of a cam shaft relative to a cam sprocket comprising:

• a vane secured to the cam shaft;
• a housing provided integral with the cam sprocket, and housing said vane so as to be relatively rotatable thereto to thereby form an advance angle side hydraulic chamber and a delay angle side hydraulic chamber on rotation direction front and rear sides of said vane;
• a valve for controlling supply/discharge of oil with respect to said advance angle side hydraulic chamber and said delay angle side hydraulic chamber;
• a resilient member for urging said vane toward an initial position;
• basic gain operation means for operating a basic gain in a feedback control of said valve;
• target value operation means for operating a target value of a rotation phase between said cam shaft and said cam sprocket;
• rotation phase detecting means for detecting said rotation phase;
• control direction judging means for judging whether a direction in which the rotation phase is changed for bringing said rotation phase close to said target value is a delay angle direction or is an advance angle direction;
• correction coefficient operation means for operating a correction coefficient for correcting said basic gain based on the result of judging the direction in which the rotation phase is changed and the target value of said rotation phase;
• feedback gain operation means for operating a feedback gain based on said basic gain and said correction coefficient;
• feedback correction value operation means for operating a feedback correction value based on said feedback gain and a deviation between the target value of said rotation phase and the rotation phase;
• and
• feedback control means for controlling said valve based on said feedback correction value.

A method of controlling a vane type variable valve timing control apparatus for changing a rotation phase of a cam shaft relative to a cam sprocket comprising:

• a vane secured to the cam shaft;
• a housing provided integral with the cam sprocket, and housing said vane so as to be relatively rotatable thereto to thereby form an advance angle side hydraulic chamber and a delay angle side hydraulic chamber on rotation direction front and rear sides of said vane;
• a valve for controlling supply/discharge of oil with respect to said advance angle side hydraulic chamber and said delay angle side hydraulic chamber;
• and
• a resilient member for urging said vane toward an initial position,
• said method comprising the step of:
• changing over a gain in a feedback control for bringing said rotation phase into agreement with a target according to a control condition.