Detecting and quantifying misfire's in I.C. engine - employing crankshaft speed sensor and paired counters for discriminating between genuine and apparent combustion irregularities.

摘要

The method for detecting and quantifying ignition irregularities, i.e. misfires, in a multicylinder IC engine involves using a crankshaft (1,2,3) sensor (4) to register an instantaneous fall in angular velocity during an expansion stroke as evidence of misfire. The misfires are counted (15) during an interval of 200 to 1000 revolutions, and on detection of an untypical increase in the number of apparent misfires a second counter (29) is triggered. Such apparent misfires are caused by dynamic change in driving conditions e.g. acceleration, road surface, ice etc. registered by the second counter (29) via a suitable sensor (31) for subtraction from the first counter total. The net total is referenced to a preset threshold for visual warning (22). USE/ADVANTAGE - Reliable indication of genuine misfires corrected for driver induced or random changes in dynamics of vehicle. Gives warning of possible damage due to overheating of catalytic converter etc..