Ignition timing control system for two-cycle internal combustion engines

摘要

An ignition timing control system for a two-cycle internal combustion engine compares a first reference signal which rises to a predetermined level as a first pulse signal is generated corresponding to a predetermined crank angle and which thereafter decays at a predetermined slope, and a second reference signal of generally trapezoidal shape and having a pulse width corresponding to the pulse width of a second pulse signal corresponding to a predetermined crank angle. When the signal level of the second reference signal rises above that of the first reference signal, an ignition signal is generated. A first reference signal control circuit generates a triangular signal in synchronism with the second pulse signal, which triangular signal rises at a predetermined slope, and controls the first reference signal in such a manner that the first reference signal decays at a slope gentler than the predetermined slope from an instant in time at which the signal level of the triangular signal exceeds a predetermined level.