On-Line Determination of Available Torque in Internal Combustion Engines

The flywheel speed is recorded during snap acceleration, while operating the engine without external load and at fully open throttle. A non-contacting magnetic sensor at the engine flywheel detects the instantaneous speed. A digital circuit, which includes a microprocessor, samples and processes the speed data. The speed increment observed over a fixed number of engine cycles is a measure of the engine torque. Since the instantaneous flywheel speed exhibits significant variations, the speed increment is determined on the basis of a linear regression analysis of the speed waveform. The approach was verified experimentally on eight-cylinder Diesel engines. The results from the snap acceleration analysis were found to be consistent with dynamometer measurements within mean relative error margins below four percent.