Adaptive method for detecting misfire in an internal combustion engines using an engine-mounted accelerometer

摘要

A method for detecting misfire in an internal combustion engine comprising the steps of measuring instantaneous angular velocity of the engine crankshaft during combustion in the combustion chamber of a piston and cylinder assembly, determining if combustion has occurred using crankshaft acceleration data, measuring engine block combustion energy vibrations by means of an accelerometer, determining whether combustion has occurred using the accelerometer data, identifying the cylinder where the acceleration data originates, comparing the results of the crankshaft acceleration information with the accelerometer information to detect whether each set of data detects misfire, decreasing the threshold for detecting a misfire using accelerometer data if a misfire is detected only by the crankshaft acceleration data whereby a reliable misfire signal can be obtained during those instances when the crankshaft acceleration data is unreliable and increasing the threshold for the accelerometer when the crankshaft acceleration data indicates no misfire but a misfire is detected by the accelerometer information.