Process and device for measuring the torque of an internal combustion heat engine

Device for producing a digital value Cg representative of an average gas torque produced by each combustion of a gas mixture in cylinders of an internal combustion heat engine operating at low speed, the engine having t periods per operating cycle and k cylinders, said device comprising:

• a number n of real or virtual measuring reference points integrally rotating with one of an inertial flywheel or a crankshaft of the engine;
• means for defining at least one indexing reference of the reference points;
• a stationary sensor sensing advancement of the reference points, mounted in the vicinity of the reference points;
• first calculating means for producing a primary digital value d.sub.i representative of an instantaneous period of advancement in front of sensor of each of the reference points;
• second calculating means for producing from n.sub.c primary digital values d.sub.i, a first secondary digital value T.sub.k representative of a total period of advancement in front of the sensor of each series of n.sub.c reference points, relating to the angular period of a combustion in the engine, ##EQU17## third calculating means for producing, from the primary digital value d.sub.i and a weighting factor cos (i.multidot.2.pi./n.sub.c) stored in a permanent memory, a second secondary digital value D.sub.k cos .phi.'.sub.k representative of a projection, on a phase reference line of the reference points corresponding to an origin of the angular periods of the combustions, of the amplitude of an alternating component of the instantaneous periods d.sub.i of advancement of the measuring reference points in front of the sensor, at the frequency of the combustions in the engine, with ##EQU18## fourth calculating means for producing a desired digital value Cg, defined by the equation
• Cg=A.multidot.(D.sub.k cos .phi.'.sub.k)/T.sup.3.sub.k +B/T.sup.2.sub.k =A.multidot.D'.sub.k /T.sup.3.sub.k +B/T.sup.2.sub.k
• from two secondary digital values D.sub.k cos .phi.'.sub.k and T.sub.k and two constants A and B experimentally determined and stored in permanent memories.

Process for producing a value representative of average gas torque Cg produced by each combustion of a gas mixture in cylinders of an internal combustion heat engine including measuring reference points rotating with one of an inertial flywheel and a crankshaft of the engine, means for defining an indexing reference of the reference points, and a stationary sensor for sensing advancement of the reference points, mounted in the vicinity of the measuring reference points, the process comprising the steps of:

• (a) producing a primary value representative of a period d.sub.i of advancement of each of the reference points in front of the sensor;
• (b) processing said primary value d.sub.i for producing two secondary values respectively representative of average angular velocity .OMEGA..sub.m on the reference points during a period of the combustions in the engine and representative of a projection E cos .phi. on a phase reference line of the reference points with respect to the angular combustion periods, E being an alternating component of an instantaneous angular velocity .OMEGA..sub.i of the reference points, at the frequency of the combustions in the engine;
• and
• (c) combining said two secondary values according to an equation:
• Cg=-a.multidot..OMEGA..sub.m .multidot.E cos .phi.+b.multidot..OMEGA..sup.2.sub.m,
• a and b being constants determined experimentally.