METHOD FOR CARRYING OUT AN IONIC CURRENT MEASUREMENT IN A COMBUSTION ENGINE USING A LEAN FUEL MIXTURE

摘要

PCT No. PCT/SE96/00406 Sec. 371 Date Oct. 3, 1997 Sec. 102(e) Date Oct. 3, 1997 PCT Filed Mar. 28, 1996 PCT Pub. No. WO96/31695 PCT Pub. Date Oct. 10, 1996A method of carrying out ionic current measurement in an internal combustion engine, using a lean fuel mixture which requires an increased burning duration, comprises the steps of (a) generating an ignition spark, (b) detecting initiation of combustion of the lean fuel mixture by the ignition spark, (c) cutting off the ignition spark within 20 microseconds after the initiation of combustion and (d) thereafter performing the ionic current measurement. The combustion start can be detected by measuring the change in the burning potential and/or the burning current, detected at the low-tension side of the secondary coil of the ignition system, using leak capacitances of the ignition coil, or by using a separate winding of the ignition coil. The ignition spark is cut off by a controllable ignition magneto.