Accelerometer Signal for Combustion Diagnosis in Diesel Engines

The combustion development in a Diesel engine is strictly dependent on the injection parameters like the number of injections, the fuel quantity, the injection timing and pressure. The combustion ignition and development, on the other hand, affects the engine block vibration response, in a peculiar way, discernible by the vibration due to the rotation of the engine. The idea of the present work is to show the monitoring capability of an accelerometer signal installed on the engine block. A series of tests, varying the injected fuel quantity, the injection pressure and the number of injections have been performed measuring the in-cylinder pressure and the vibration signal. Classical Fourier transform and time frequency methods have been applied to the engine block vibration and to the pressure signals, in order to show their correlation.