Process and device for measuring the torque of an internal combustion heat engine taking into consideration, in particular, the recirculation of exhaust gases and residual burnt gases and excess oxidant

Claim 1

System for measuring digital value Cg, representative of an average gas torque per combustion of a gas mixture in k cylinders of an internal combustion engine having t periods per operating cycle, said system comprising: a number n of measuring reference points integrally rotating with one of an inertial flywheel and an crankshaft of the engine; means for defining at least one indexing reference of the reference points; a stationary advancement sensor for the reference points, mounted in the vicinity of the reference points; first calculating means for producing a primary digital value d i , representative of an instantaneous advancement period in front of sensor, of each of the reference points; second calculating means for producing from the primary digital value d i a first secondary digital value T k representative of a total period of advancement in front of the sensor of each series of n c reference points, relating to the angular period of a combustion in the engine, ##EQU10## third calculating means for producing, from the primary digital value d, and weighing factor cos(i.2π/n c ) stored in a permanent memory, a second secondary digital value D k cosφ' i representative of a projection, on a phase reference line of the reference points corresponding to an original of the angular periods of the combustion, of the amplitude of an alternating component of the instantaneous periods d i of advancement of the measuring reference points in front of the sensor, at the frequency of the combustion in the engine, with ##EQU11## fourth calculating means for producing desired digital value Cg, defined by the equation Cg=A.(D.sub.k cosφ'.sub.k)/T.sup.3.sub.k +B/T.sup.2.sub.k =A.D'.sub.k /T.sup.3.sub.k +B/T.sup.2.sub.k from two secondary digital values D k cosφ' k and T k and two constants A and B experimentally determined and stored in permanent memories; a device for correcting digital value Cg as a function of a total rate q of recirculation of exhaust gases (RGE) and residual burnt gases (GBR), said correcting device comprising fifth calculating means for producing a correction factor Q 2 =(1-p 1 .q), in which p 2 is an experimentally determined constant close to 0.50 and q is a value of said total rate, and for applying Q 2 to value Cg, corrected as a function of richness r of the gas mixture, for providing a corrected digital value (Cg) q or (Cg) r ,q.