Electronic ignition system for IC engines - uses computer accepting engine data for use as pointer to look-up table held in ROM giving correct advance

摘要

The ignition system has an ignition triggering circuit (1) comprising a computer (2) and a read only memory (3) in which are stored look-up tables for ignition advance. The vacuum in the inlet manifold is converted to a variable (analog) voltage (V1) by a transducer. This voltage is applied to an analog-to-digital converter (5) in the computer unit via an operational amplifier circuit (20) which mixes in data on engine speed and temperature, and accepts a switched input (138) derived from the position of the throttle butterfly (139). The resulting output signal (V3) is converted to digital representation (5) and the computer uses this data to access the ignition advance look-up table, obtaining the correct advance value and using it to control the instant of generation of the ignition pulse.