Device for detecting misfire of an internal combustion engine by comparing voltage waveforms associated with ignition system

摘要

In equipment for recognizing misfire in an internal combustion engine, a first voltage waveform is obtained at an intermediate point (A) between a high impedance element (41) and a low impedance element (42). The first voltage waveform has a capacitive discharge component and an inductive discharge component during the spark and a voltage component after completion of the spark. The first voltage waveform is inversely amplified by a comparator (51) and divided by a shunt circuit (52) to obtain a second voltage waveform. In an integration circuit (53), a condenser (C1) is electrically charged by an output voltage from the comparator (51) to obtain a third voltage waveform. The second voltage waveform and the third voltage are compared by a comparator (54) to generate an output pulse. On the basis of the behavior of relatively short and relatively wide output pulse (d2, D2) and additional short output pulses (d3, d4) from the comparator (54), it is determined whether or not a misfire has occurred in the internal combustion engine.