RECONSTRUCTION OF DIESEL ENGINE CYLINDER PRESSURE USING A TIME DOMAIN SMOOTHING TECHNIQUE

The time waveform of engine cylinder pressures is the most useful parameter in evaluating cylinder working procedures, such as compression, combustion and expansion in a diesel engine cylinder. Unfortunately, direct measurement of cylinder pressure signals is impractical because installing pressure transducers is difficult as well as uneconomical for general use. Therefore, indirect derivation or reconstruction of such signals from externally measured engine vibration is desired. Different procedures have been developed to reconstruct cylinder pressures from externally measured vibration responses. In this paper, the theories of existing procedures are reviewed. Also the Laplace transform (LT) is used to design a time-domain smoothing technique. The properties of this technique were investigated theoretically. Then it was applied to reconstruct cylinder pressures from response vibrations measured externally on a single-cylinder diesel engine, and the results obtained corresponded well with the measured pressure waveforms.