Patent ID: 6880504
Filing Date: 2005-04-19
Classification: F01L

Abstract:
1. A valve timing control apparatus for an internal combustion engine comprising: sensor means for detecting operating conditions of said internal combustion engine; a crank angle sensor for generating a crank angle signal including a train of pulses which correspond respectively to rotational angles of a crankshaft of said internal combustion engine; an intake camshaft and an exhaust camshaft for driving intake and exhaust valves, respectively, of said internal combustion engine in synchronization with the rotation of said crankshaft; cam angle changing means mounted on at least one of said intake and exhaust camshafts for changing the phase of said at least one of said camshafts relative to said crankshaft; a cam angle sensor mounted on said at least one camshaft whose phase relative to said crankshaft is changed by said cam angle changing means, for generating a cam angle signal for identifying respective cylinders of said internal combustion engine and for detecting a cam angle of said at least one camshaft whose relative phase to said crankshaft is changed by said cam angle changing means; reference crank angle position calculation means for calculating reference crank angle positions based on said crank angle position signal; cam angle calculation means for calculating said cam angle based on said crank angle signal and said cam angle signal; and cam angle control means for controlling said cam angle changing means based on the operating conditions of said internal combustion engine and said cam angle calculated by said cam angle calculation means in such a manner that the phase of said camshaft relative to said crankshaft is controlled so as to coincide with a target cam angle which corresponds to the operating conditions of said internal combustion engine; wherein said cam angle calculation means calculates said cam angle by counting the number of pulses of said crank angle signal; and wherein said cam angle control means comprises cam angle learning means for learning reference positions of said cam angle, wherein when said cam angle changing means is out of operation, said cam angle learning means learns an angular deviation between said cam angle calculated by said cam angle calculation means and a designed value of said crank angle position.