Vibration monitoring system for marine diesel engine

Vibration signal analysis is generally regarded as one of the most effective methods used in mechanical condition monitoring and fault diagnosis and has been successfully utilized in condition monitoring for various of rotating machinery. Structure faults of diesel engine usually affect exciting forces or propagation behavior of local vibration signals and induce different vibration responses on engine surface. Compared to other symptomatic parameters vibration signal possesses advantages of easy data acquisition, strong monitor directionality, high detection precision, early condition prediction and is especially sensitive to mechanical conditions of significant components such as piston-liner, valve mechanism, fuel oil injector, turbocharger bearing, main journal bearing, etc. Experimental research and theoretical analysis carried out during author's doctoral and post-doctoral research period has made more clear the excitation and propagation of superficial local vibration signals, revealed the relationship between internal exciting forces, external local vibrations, engine performance conditions and mechanical faults of diesel engine, explored a new method to get over the difficulties of present vibration analysis method in practical use of diesel engine fault diagnosis. This paper briefly summarizes vibrational diagnosis mechanisms of worn-out piston-liner, abnormal valve clearance, exhaust valve leakage and worn-out main journal bearing, introduces the hardware design and software interfaces of vibration monitoring system for marine diesel engine.