Method and apparatus for detecting the angular position of a variable position camshaft

In combination,

• an internal combustion engine comprising a plurality of cylinders, each firing in a predetermined sequence,
• a variable position cam shaft comprising a plurality of cam lobes, said camshaft rotating in a variable angular relationship to an engine crankshaft,
• a pulsewheel positioned on said cam shaft comprising a plurality of teeth,
• a cam position sensor, responsive to the angular rotation of said pulsewheel, for generating a first pulsetrain comprising a series of pulses indicative of the angular positions of said camshaft;
• an engine position sensor generating a second pulsetrain comprising a series of pulses indicative of the rotational speed of said engine;
• and
• a variable cam sensing system comprising,
• means, responsive to exactly said first and said second pulsetrains, for identifying a first firing cylinder in a predetermined firing sequence,
• means, responsive to said first and said second pulsetrains, for determining the time duration between certain pulses of said first and said second pulsetrains, and
• means, responsive to said time duration, to the rotational speed of the engine and to a value indicative of the number of cylinders in the engine, for determining the angular position of said camshaft in relation to the crankshaft.

In an internal combustion engine comprising a variable position camshaft which is movable in a variable angular position in relation to an engine crankshaft, a method for determining the angular position of the camshaft in relation to the crankshaft, comprising the steps of:

• generating an engine position signal comprising a first series of pulses indicative of the rotational speed of said engine crankshaft;
• generating a cam sensor signal comprising a second series of pulses indicative of the rotation of said camshaft by a predetermined angle;
• and
• calculating the angular position of said camshaft in relation to the crankshaft as a function of the relationship between certain pulses of said first series of pulses and certain pulses of said second series of pulses, and as a function of the rotational speed of the engine and as a function of a value indicative of the number of cylinders in the engine.