Diagnosis of valve-slap of diesel engine with EEMD-EMD-AGST approach

A hybrid of ensemble empirical mode decomposition and empirical mode decomposition (EEMD-EMD) is introduced to diagnose the valve-slap vibration signal, which is relative to the dominant combustion knock vibration signal given out by a diesel engine around the top dead center (TDC). The time-frequency representations of intrinsic mode functions (IMFs) decomposed by EEMD-EMD are obtained by adaptive generalized S transform (AGST). A type 493 diesel engine was used for the experiment, and the result indicates that the valve-slap of the diesel engine is serious, and the vibration frequencies are higher than the combustion knock. With EEMD-EMD-AGST approach, the valve-slap can be identified by the vibration analysis of the diesel engine.