Method and system for detecting the misfire of a reciprocating internal combustion engine utilizing a misfire index model

摘要

A misfire index model-based method and system for detecting misfire in a reciprocating internal combustion engine having an engine cycle frequency in the frequency domain from crankshaft angular velocity. The misfire index model is a function of engine operating condition such as engine load and RPM. Crankshaft angular position is sensed to develop an electrical signal which is a function of the crankshaft angular velocity. The electrical signal contains data which is sampled. The sampled data is transformed to an equivalent frequency domain spectrum including frequency components of the engine cycle frequency and harmonics thereof. A load signal such as mass airflow and an RPM signal are generated. The magnitudes and/or phases of the frequency components and the load and RPM signals are supplied to the misfire index model in an appropriately programmed computer to distinguish between a true misfire and normal cyclic variability which characterizes the combustion process.