REAL-TIME DETERMINATION OF THE IN-CYCLE EVOLUTION OF THE TURBOCHARGER SPEED IN INTERNAL COMBUSTION ENGINES

Most of the internal combustion engine phenomena (scavenging process, injection, combustion, expansion, etc.) are repeated during an engine cycle as many times as cylinders are present in the engine. This cyclic behavior influences the instantaneous angular speed n = dtheta/dt (IAS) of the turbocharger. By measuring IAS, it can be possible to diagnose the correct performance of the engine and, in some cases, to correct deviations of the engine's operation from the expected behavior. The influence of the engine behavior on the turbogroup can be seen as small variations in the order of tens of revolutions per minute. If we take into account that a turbogroup on a commercial vehicle can rotate at speeds up to 250,000 r.p.m., then an IAS measurement method proposal should provide high resolution and a bounded absolute error. In addition, it is required to know nt(theta) of the turbogroup, where theta represents the cycle of the engine, in order to analyze the engine's cycle.