Fault Identification in SI Engines Using the TDA - Time Domain Average

Although regular visual inspections and the preventive maintenance can help in fault reduction in SI Engines, the cost and the time required to execute such procedures has made them economically unviable. To avoid this problem, several methodologies using vibratory signals signatures analysis have been developed to examine the conditions of these systems. The objective of this work is to show how the TDA (Time Domain Average) can be used, together with the Cepstrum analysis, as a powerful tool in the faults identification in SI Engines. The signals are originated from external measurements done in the FIAT-Automóveis' test workbench, localized in Betim/MG. In the first part of this work is shown the basic concepts and formulations for the TDA and for the Cepstrum analysis. Finally, a practical example, in which is introduced a known fault - valves chatter in the engine, is then fully described to illustrate the advantages of the use of TDA in the SI Engines fault identification.