Research On Fault Diagnosis And Operation And Maintenance Technology Of Marine Diesel Engine Cooling System

Cooling system is one of the most important auxiliary system of diesel engine.It provides cooling water with appropriate pressure,temperature and sufficient flow to the main engine to maintain the diesel engine working in the best temperature environment,so as to ensure its best working efficiency and long-term service life.The reliability of the cooling system will have a great impact on the operation of the main engine.In practice,diesel engine faults caused by cooling system faults are common.The establishment of cooling system fault diagnosis system is particularly important to find and eliminate faults in time and ensure the normal and reliable operation of diesel engine.The fault diagnosis system needs the support of fault data.Obtaining fault data through experiments not only requires a large cost,but also some faults will cause irreversible damage to the equipment.Based on the simulation software to simulate the fault and obtain the fault data,it not only saves the cost,but also avoids the damage of the equipment.It is an important link in the development of fault diagnosis system at present.This paper taking 7G80ME-C diesel engine cooling system as the research object,according to its working principle,the diesel engine cooling system model is established in the simulation platform;The bench test scheme of diesel engine cooling system is designed from the aspects of test equipment selection,temperature sensor layout,experimental circuit design and signal acquisition system design;The experimental data are recorded to verify the accuracy of the simulation model.According to many years of working experience in following the ship,the faults of diesel engine cooling system are comprehensively summarized,and four typical faults are selected according to the frequency of faults;Five kinds of cooling system performance parameters are selected by fault tree analysis;Then,four typical faults are simulated,the variation laws of five performance parameters under different faults are analyzed,and the fault data are obtained;Using fault data as a sample set,Based on BP neural network(BPNN)establish the fault diagnosis model.The simulation model is established according to the working principle of 7G80ME-C diesel engine,and the accuracy of the model is verified based on the test data.The coupling simulation model of diesel engine working process cooling system combustion chamber is established by using the lumped parameter method.Aiming at the two typical faults of high temperature fresh water pump and dirty blockage of central cooler,the steady-state performance of diesel engine is analyzed The effects of performance and dynamic performance are studied.The results show that the fault diagnosis model can accurately diagnose four kinds of faults through the changes of five performance parameters,which proves that the fault sample set provided by the fault simulation in this paper is complete and can provide support and help for the fault diagnosis of diesel engine cooling system.When the parameters such as thermal resistance of central cooler and high temperature fresh water flow change to a certain extent,it will improve the economy of diesel engine,but also increase the mechanical load and thermal load of diesel engine;The failure of diesel engine cooling system will affect the working performance of diesel engine and turbocharger by affecting the intake temperature and wall temperature of diesel engine.The research results of this paper can provide some theoretical support for the safe and efficient operation of diesel engine.