JPS57157061A - Ignition timing control system - Google Patents

Abstract

PURPOSE:To enable to move a motorcar in case the trouble or the like of a microcomputer by a method wherein an ignition signal having a proper ignition timing based on the standard position pulse of the rotation of an engine and a crank angle detecting pulse is outputted from the microcomputer automatically. CONSTITUTION:The standard position detecting pulse So is outputted at a time when the protruded part of a magnetic disc on a crank shaft is passing a standard position sensor and it is offeringly inputted into the microcomputor 4. On the other hand, at every time when 180 pieces of protuberances of another magnetic disc on the same shaft is passing a crank angle sensor, the crank angle detecting pulse S1 is outputted, then, the frequency of the pulse S1 is multiplied two times and is turned to the pulse S2 while the pulse S2 is inputted into an input terminal T1 at every time when the crank shaft is rotated once. In the microcomputor 4, a control pulse S5, making an energy accumulating time for an ignition coil 14 constant, is outputted by the detecting pulse So and the multiplied pulse S2 and thereby determining the ignition timing. Further, when the microcomputor or the like is abnormal, the ignition timing is determined based on a pulse S3 determined by a counter 7 counting the frequency multiplied pulse S2 and a decoder 8.