Diagnosis of internal combustion engine through vibration and acoustic pressure no – intrusive measurements

The present study proposes a diagnosis methodology for internal combustion engines (I.C.E.) working conditions, by means of non-invasive measurements on the cylinder head, such as acoustic and vibration, related to the internal indicated mean effective pressure. The experimental campaign was carried out on the internal combustion engine of the cogeneration plant at the Faculty of Engineering – University of Perugia (Italy), for different values of the engine load. Results show that both the vibration and acoustic signals measured on the cylinder head are strictly related to the phenomena inside the cylinder, depending on the engine load and the combustion frequency. Some vibration and acoustic indexes were introduced, in order to evaluate the working regimen of the engine. Their values, obtained for different engine loads, constitute the reference values; when the methodology was implemented, the evaluation of such indexes allows to estimate the combustion quality, comparing measured and reference values.