TOTAL LOSS TORQUE WAVEFORM ESTIMATION FOR A TURBOCHARGED DIESEL ENGINE.

The indicated (gas) torque is a key parameter for reciprocating engine. It reports on various aspects of the engine, such as the quality of the combustion process, the fuel combustion rate and the average effective pressure. This is a good indicator of the stability of the engine at work. The form of the instantaneous indicated torque is precious information for the control and diagnosis of the engine. The study of the simulation of crankshaft dynamics illustrates the need to know the total loss torque (i.e. the addition of friction torque, auxiliary torque and load torque) to achieve the indicated torque. To date, it has proven difficult to obtain an accurate predictive expression of the instantaneous total loss torque. This expression includes adequate simulation of friction of all moving parts of the engine (piston ring and skirt, crankshaft bearings, valve gear...), auxiliaries and load. Based on experimental results conducted on a four-cylinder turbocharged diesel engine, this work offers a simple and practical solution for estimating the total torque loss. The proposed method makes it possible to successfully estimate total torque losses under a wide range of engine operating conditions. The result prediction has been confronted to experimental data.