Contactless ignition system for internal combustion engine

Abstract

A contactless ignition system of current interruption type for an internal combustion engine comprising at least one pulser device sensing a predetermined maximum advance position and a predetermined minimum advance position of the ignition timing to generate an output signal indicative of such advance positions. On the basis of the output signal of the pulser, a first ramp signal having a first gradient and a second ramp signal having a second gradient are produced, and a signal representing the sum of a reference signal of a constant level and the second ramp signal is compared in a comparator with the first ramp signal. When level coincidence is reached between these two signals, the comparator generates a control signal controlling the turn-on position of a semiconductor switch which controls the ignition timing, so that the duration of current supply for ignition can be maintained substantially constant throughout the rotation speed ranges of the engine.