Ignition system for internal combustion engines

Ignition system for an internal combustion engine including an ignition coil, in the primary circuit of which an electronic switch and in the secondary circuit of which at least one spark gap is connected, apparatus for controlling the dwell angle for control of the switching times of said electronic switch in dependence on the signals of an ignition timing sensor, said sensor providing only a single signal per ignition event, and a counting apparatus in which speed dependent counting values are determined periodically and are counted down, each value under control of one edge of a signal from said sensor, the electronic switch being closed upon reaching of a settable triggering counting value, said system further comprising:

• means for simultaneously initiating the count-down of said speed dependent counting value and the opening of the electronic switch (21) in response to said one edge of a signal from said sensor, and
• means for setting said triggering counting value by periodic up and down counting processes, the upwards count in processes being constant in time and the downwards counting processes being determined by the length of time of current flow of current in excess of a presettable current value through the ignition coil (23).