Early Fault Diagnosis Of Diesel Engine Based On Acoustic Emission

Due to their advantages,diesel engines have been widely used in engineering machineries,heavy-duty vehicles,large-scale generating units and warships in the field,which are closely related to the national production and the defense industry.But before the formal "retire",the diesel engine may experience many failures.Before the failure occurs,there will be some weak signs.If early detection and preventive measures can be implemented,cost savings can be achieved.In this paper,acoustic emission detection technology is used to diagnose and analyze the early fault diagnosis of diesel engine by collecting acoustic emission signals from diesel engine body surface and then using advanced acoustic emission signal processing technology.The acoustic emission signal of diesel engine body surface contains comprehensive state information,which can fully characterize the health state of diesel engine and early defects and hidden trouble.This paper's innovation: non-stop,do not disintegrate the state detection of diesel engine early weak fault.Its main work is based on acoustic emission signal analysis of diesel engine early fault diagnosis,the specific work is as follows:1)In order to diagnosis and analyse of abnormal acoustic emission signal of a single cylinder diesel engine,the vibration sensor and the acoustic emission sensor are mounted in the diesel engine cylinderblock,using wavelet multiresolution algorithm comparison analysis of the two sensor signals.Firstly through the geometry estimate abnormal signals may correspond to the two faults is proposed.Then according to the teardown inspection,confirm the acoustic emission signal of fault feature from piston assembly between the abnormal friction events.Diagnostic results shown that: due to the unreasonable design of the structure and size of the types of single cylinder diesel engine piston assembly,in the normal work of the diesel engine,small head of the connecting rod and piston internal occurred friction events,and led to the acoustic emission signal in fixed crankshaft angle appear abnormal peak response.Acoustic emission technique provides a more accurate diagnosis method for the effective monitoring of the friction and wear of the piston assembly in the future.2)In order to diagnose and analyze the abnormal acoustic emission signal sources of a single-cylinder diesel engine,acoustic emission sensors are arranged in different parts of the engine body,and the abnormal response of different parts of the acoustic emission peaks is analyzed by wavelet analysis to realize the fault location and recognition of diesel engine oil pressure abnormality.It is first determined that the abnormal acoustic emission peak response of the sensor arranged between the oil pump and the oil filter is maximum and then the structure around the acoustic emission sensor which may generate an abnormal signal is analyzed and inspected to confirm the fault characteristics in the acoustic emission signal from the pressure limiting valve seat event caused by high oil pressure.The diagnostic results show that the oil pressure of the single cylinder diesel engine was set too high by the manufacturer,which not only lead to additional power consumption but also cause high mechanical impacts due to the strong landing of the valve core.These diagnostics show that the AE technology provides a non-intrusive and yet sufficiently accurate for the monitoring and early fault diagnosis of internal combustion engine lubrication system.