Dual threshold low coil signal conditioner

Abstract

The end of the dwell period of a spark ignition engine is recognized by a high voltage, spark-creating swing in the low coil signal determined from comparison with a first, fixed threshold voltage which is above the current limited voltage variation of modern electronic high voltage ignition systems and a low peak primary voltage normally achieved with ignition defeat used in other diagnostic procedures. The beginning of the dwell period is sensed by comparing the low coil signal to the actual battery voltage of the engine under test; the comparison is against a substantial fraction of battery voltage which will always exceed any low coil voltage which could exist during the dwell period. False sensing of the beginning of dwell during the spark ringing time is avoided by delay circuitry which senses only those low voltage swings which exist for longer than a period of time greater than the duration of any of the low voltage excursions of the low coil ringing voltage; this delay may be subtracted with logic or by digital numeric subtraction, thereby to provide a reliable, square, conditioned low coil manifestation of vehicle low coil signals for vehicles with modern electronic high voltage ignitions as well as vehicles using the older, traditional breaker point ignition system, at high speed or slow crank, with good or bad battery and/or alternator.

Dependencies are inferred from the claim text.