Electronic ignition control apparatus

Claim 1

An electronic igintion control apparatus for an internal combustion engine having an output shaft rotated by a piston, an ignition coil adapted to generate a spark voltage upon de-energization of the primary winding thereof, a spark plug activated by the spark voltage to ignite the air-fuel mixture metered into a combustion chamber of said engine so as to operate said piston, and an exhaust gas recirculation device to recirculate exhaust gas into the combustion chamber of said engine, the control apparatus comprising: a first signal generator for producing a first signal at a predetermined angular interval of rotation of said output shaft; a second signal generator for producing a second binary signal indicative of an instant rotation speed N of said output shaft in response to the first signal; a third signal generator for producing a third binary signal indicative of an instant amount Ga of the sucked air into the combustion chamber of said engine in response to the first signal; a fourth signal generator coupled with said exhaust gas recirculation device for producing fourth and fifth signals respectively indicative of activation and deactivation of said exhaust gas recirculation device; a single memory means for storing first data indicating an optimum spark advance angle for activation of said spark plug in relation to the instant rotation speed N and the instant amount Ga of the sucked air in consideration with exhaust gas recirculation of the combustion chamber of said engine, which optimum spark advance angle is given by a value θ ij ° which is indicated in a specific range defined by rotation speeds N i-1 and N i and amounts Ga j-1 and Ga j of the sucked air in the form of a table or map, said memory means further storing second data indicating an optimum spark advance angle for activation of said spark plug in relation to the instant rotation speed N and the instant amount Ga of the sucked air, which optimum spark advance angle is give by a value θ ij ° which is indicated in the specific range represented in said table or map, said memory means producing a sixth binary signal representing the first-named optimum spark advance angle in accordance with the second and third binary signals in response to the fourth signal and producing a seventh binary signal representing the second-named optimum spark advance angle in accordance with the second and third binary signals in response to the fifth signal; a timing signal generator for generating a timing signal in accordance with one of the sixth and seventh binary signals; and means for de-energizing the primary winding of said ignition coil in response to the timing signal.