Misfire detector with crankshaft tachometer for combustion engine - invalidates alarm signals from conventional detector when engine speed exceeds or load falls below predetermined value

摘要

A conventional sensor (1) of pulses synchronised with rotation of the crankshaft feeds a circuit (2) which evaluates the angular velocities at two predetermined positions, before and after TDC. A speed deviation calculator (3) drives a misfire detector (4) emitting a signal (9) when the deviation is within a given limit. A crankshaft tachometer (10) is added with an engine load sensor (11) enabling a misfiring-range detector (12) to recognise failures of ignition and to authorise or inhibit (16) signals from the detector (4). ADVANTAGE - More reliable detection of misfiring is guaranteed without false alarms in particularly unfavourable operating conditions.