Theory And Its Application Based On The Diesel Engine Shaft Torsional Vibration Fault Diagnosis

Using mechanical fault diagnosis technique,we can reduce unexpected accidents and save maintenance cost. Diesel engine has rather complex structure, so different methods and theories should be used to diagnose its faults.Due to its advantages of easy data acquisition,comparatively mature vibration theories and measuring instruments,high detection precision,abundant signals and strong monitor directionality, vibration diagnosis is applied to mechanical condition monitoring and fault diagnosis extensively. As a vibration diagnosis,the shaft system torsion vibration diagnosis for diesel engine is a new technique.When a diesel engine runs,its shaft system might move aternately and cyclically and produce corresponding deformation with both the effect of its own inertia and elasticity and the action of exciting forces,as is called torsion vibration.The exciting forces are caused by the changes of the air pressure in cylinders,inertia forces of the crankshaft and the connecting rods etc.These exciting forces can be made simple harmonic analyses.Under normal condition of a diesel engine,the torsion vibration characteristics of shaft system have good regularity. When the working process faults takes place,the exciting forces changes,the torsion vibration characteristics also changes.So the characteristic states parameters can be picked up from the torsion vibration characteristics to diagnose the working process faults of a diesel engine.as long as suitable methods are adopted. This dissertation mainly applys the theory above to practice and makes a practical application research.Using a ANZT torsion vibration measuring instrument made in china, author measures torsion vibration of 6121Z1 diesel engine. The state parameters of normal state and No.1,No.3,No.4 cylinder ie out?states are obtained. From these parameters,twenty characteristic parameters per state are picked up.Combining the characteristic parameters with a pattern recognition method based on fuzzy grey incidence,this dissertation diagnoses the diesel engine faults. Result shows that the diagnosis effect is good. So this dissertation concludes that the pattern recognition method based on fuzzy grey incidence is effective,the practical application of the torsion vibration diagnosis theory is successful. These conclusions are highly significant for developing condition monitoring and fault diagnosis. This dissertation proposes a little torsion vibration condition monitoring and fault diagnosis system,briefly introduces its four components and its application to ocean ship. This dissertation divides all the contents above into six parts: the summary of fault diagnosis of marine diesel engine,the theoretical analysis of torsion vibration diagnosis, the diagnosis model of recognition method based on fuzzy grey incidence, practical application research, the conclusions and further research contents. Wang Jiahong (Fault Diagnosis for Marine Diesel Engine) Directed by Prof.Ying Qiguang...