Importance

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Abstract

An electronic ignition system is disclosed for controlling as a function of a selected engine parameter the ignition instant of an internal combustion engine having at least one cylinder and a piston disposed therein and coupled to a rotatable crankshaft of the engine to define a first reference position with respect to the crankshaft. The ignition instant occurs upon the termination of an arc of crankshaft rotation at a second variable position with respect to the first reference position. The arc of crankshaft rotation is initiated at a third reference position fixedly disposed before said first reference position considering the rotational direction of the crankshaft. More specifically, the electronic ignition system comprises a first sensor responsive to crankshaft rotation for providing a first train of signals of a first frequency, each first signal occurring in time when the crankshaft rotates past its third reference position, and a second sensor responsive to crankshaft rotation for providing a second train of signals of a second frequency greater than the first frequency and proportional to the speed of angular rotation of the crankshaft. A counter is coupled to receive the first and second trains of signals and actuated upon the occurrence of each signal of the first train for integrating the second train of signals to obtain an indication of the present crankshaft position with respect to said first variable position. The present crankshaft position is used to determine the ignition instant.

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First Claim