Device for refining the adjustment of the ignition advance of a controlled-ignition internal combustion engine

A device for regulating ignition advance of a controlled-ignition system internal combustion engine having a crankshaft, a plurality of cylinders each having a combustion chamber, a piston in each cylinder, and means for directing a combustible fuel-air mixture to said cylinders, said device comprising an electronic circuit, a first sensor means disposed in the combustion chamber of at least one cylinder and connected to said electronic circuit for producing a first start-of-combustion signal, a second sensor means for detecting the position of the piston of said one cylinder when at top dead center, said second sensor means being connected to said electronic circuit for providing a second signal, a third sensor means disposed in a zone very far from the said first sensor means inside the combustion chamber of the same cylinder and connected to said electronic circuit for producing a third end-of-combustion signal, first processing means for generating from said first and second signals a fourth signal corresponding to the angle .alpha. through which the crankshaft rotates from the moment of the start of combustion in said combustion chamber to the position corresponding to the top dead center of the piston in said one cylinder of the engine, and second processing means for generating from said second and third signals a fifth signal corresponding to the angle .beta. through which the crankshaft rotates from said top dead center position up to the moment when the combustion of the combustible mixture in said one cylinder is practically terminated;

• said electronic circuit comprising comparator means for comparing the signals corresponding to the angles .alpha. and .beta. to determine whether a .alpha./.beta. ratio is lesser or greater than a pre-established value K which corresponds to a preselected optimal ignition advance angle, said comparator means including means for sending positive or negative command signals to the engine ignition system for increasing or decreasing the ignition advance angle in accordance with the relation of the detected .alpha./.beta. ratio to the value K.