Patent ID: 6729280
Filing Date: 2004-05-04
Classification: F01L

Abstract:
A reference position learning apparatus of a variable valve-timing controlling system, which changes a rotational phase of a camshaft relative to a crankshaft of an engine to control valve timing of the engine, comprising:a crank angle sensor that generates a rotation-detection signal of the crankshaft; a cam sensor that detects a plurality of detection subjects provided for the camshaft so as to be arranged in a rotating direction of the camshaft, to generate a rotation-detection signal for each of the plurality of detection subjects; and a control unit for determining a rotational phase for use during learning of said camshaft reference position based on a detected current rotational phase and at least a detected previous rotational phase, wherein a degree of smoothening of said current rotational phase applied during determination of said rotational phase being dependent on at least one of the number of previous rotational phases taken into account and a weighing factor assigned to said previous rotational phase and wherein the degree of smoothening of said current rotational phase being larger during learning of said camshaft reference position compared to a smoothening degree applied to a current rotational phase in determining a camshaft rotational phase during a valve timing control.