Ignition system for internal combustion engines

Claim 1

Ignition system for an internal combustion engine having an ignition coil (131); a controlled switch (130) serially connected with the primary of the ignition coil (131) and controlling the commencement and interruption of current flow therethrough; a control signal source (10, 11) coupled for rotation with the engine and providing ignition control pulses to determine the opening instant of said controlled switch (130) and hence determining the ignition instant of said system; a timing circuit (12) connected to and controlling the time instant of connection of the controlled switch (130) for said current flow therethrough and through the ignition coil; connection timing control means (16, 18, 20; 17, 19, 21) responsive to the recurrence rate of ignition pulses providing a control signal representative of said recurrence rate, and hence speed of the engine, connected to and controlling the timing circuit (12) to thereby control the time instant of connection of the controlled switch (130) subsequent to a prior opening thereof as a function of engine speed including an integrator means (16, 17) integrating during the time of subsequent recurrent ignition pulses, and providing said control signal as a function of the integration time to said timing circuit, the timing circuit commanding closing after a prior opening at time instants which variably follow said prior opening as the recurrence rate of said ignition pulses changes, to maintain the closed or ON-time of said controlled switch (130) essentially constant as the speed of the engine varies; and further including a memory means connected to the integrator means and storing a signal representative of the integrated value integrated by said integrator means over the time between successive pulses, the memory being connected to said timing circuit to control timing interval thereof.