Combustion engine ignition timing system

Claim 1

Ignition timing control system for internal combustion engines, comprising: shaft position transducer means (18) providing a position signal representative of a predetermined angular position of the crankshaft of the engine; pulse transducer means (10) providing a train of sequential signals upon rotation of the shaft; a wave-shaping circuit (15) triggered by the pulse transducer means (10) and providing sequential similar pulses; a gate (16) energized by the position signal connected to pass the sequential signals upon energization by the position signal; an accumulator (9) having a pulse conversion stage (23) providing an output voltage representative of the number of pulses after energization of the gate (16), and an integrator and memory stage (24) storing the instantaneous accumulated voltage representative of the instantaneous angle of rotation of the crankshaft after energization of the gate (16) to provide a progressively increasing output voltage representative, at any instant of time, of the instantaneous position of the shaft after occurrence of said position signal; a control voltage generator (25) connected to the position transducer means (18) and, upon being triggered by said position signal, generating a time-varying command voltage having a nonlinear time-voltage relationship, and depending on at least one operating parameter of the engine, representative of a commanded ignition instant with respect to said predetermined angular crankshaft position; And a comparator (27) comparing the output voltage of the control voltage generator (25) and of the accumulated votage of the accumulator (9) and providing an output indicative of the ignition instant, as commanded by the control voltage generator (25) upon rotation of the crankshaft to the commanded position, as represented by the accumulated signal.