Misfire monitoring circuit for IC engine with elimination of false signals - applies voltage to firing chamber after firing to monitor ion current through burn and uses reference programme to eliminate spurious events

摘要

The ignition system for the IC engine has a voltage generator (10b) which applied a voltage to the firing chamber between the spark plug and an electrode, or between sampling electrodes. The ion current generated is measured at set intervals in the secondary of the ignition coil circuit. The signals are stored in a memory and compared with reference patterns to determine if they correspond to a burn pattern. The sampling is at set intervals during a sampling period which includes the period for maximum ignition. The decay rate of the ion current gives a measure of the type of burn, or the absence of ignition. The misfires are counted and if they exceed a set rate then corrective action is taken by the engine management system. ADVANTAGE - Accurate determination of misfires; elimination of spurious signals.