Some New Diagnostic Parameters for Reciprocating Engines

Condition monitoring through signal analysis is not as well established for reciprocating engines as it is for rotating machines. One of the reason is that it has to deal with non-stationary vibrations. In this paper, some new statistical indicators are defined for the detection and separation of close transient events. They can also be used for diagnostic purposes, for instance for valve mechanics or for combustion rises. Their performances are compared on real vibrations of a small 4 cylinder diesel engine and it is finally verified that they allow the reconstruction of the engine cycle.