Apparatus for detecting the rotational position of the crankshaft of an internal combustion engine

Claim 1

Apparatus for detecting the rotational position of the crank shaft in an internal combustion engine having a plurality of cylinders, comprising: trigger wheel means mounted for rotation at a speed proportional to the rotation of said crank shaft; a plurality of marker means and an additional reference means respectively associated with one of said cylinders and provided on said trigger wheel means at predetermined spacings from each other for movement therewith, each of said marker means being of a first length and said reference means being of a second length greater than said first length, said first and second lengths relating to predetermined angular displacements of said crank shaft; first sensing means responsive to said marker means and said reference means during movement of said trigger means for providing first marker means signals and first reference means signals; second sensing means positioned from said first sensing means by a distance less than said predetermined spacings and less than said second length and responsive to said marker means and said reference means during movement of said trigger wheel means for providing second marker means signals and second reference means signals identical to but out of phase with said first marker means signals and reference means signals; and signal processing means comprising first and second input terminals connected to said first and second sensing means, respectively, a first output terminal for passing said first marker means signal from said first sensing means, means for combining said first and second reference means signals, and a second output terminal for passing said combined reference means signal from said combining means.