Patent Document ID: 5562071
Application ID: 08512397
Patent Flag: 1

Claim One:
1. An engine valve operation timing control apparatus, comprising: a phase control mechanism, provided within a path for transmitting rotations from a crankshaft to a camshaft within an engine, for varying a rotational phase difference between the shafts; driving means for driving said phase control mechanism; operating condition detecting means for detecting a plurality of operating conditions representing operating conditions of said engine; rotational phase difference detecting means for finding an actual phase difference angle between said shafts based on the operating conditions detected by said operating condition detecting means; target value deciding means for deciding a target value of the rotational phase difference based on the operating conditions detected by the operating condition detecting means; and control means for generating a control value for causing said actual phase difference angle to coincide with said target value of the rotational phase difference and for outputting said control value to said driving means; wherein said control means includes first determining means for determining whether said actual phase difference angle is almost constant for a predetermined time, learning means for learning said control value when said actual phase difference angle becomes almost constant for the predetermined time, and a controller for finding a control value thereafter based on the learned value.