Research On Diesel Engine Reliability Allocation On The Cost Function

In recent years,China’s economic and social development has been sustained and rapid development.,the number of car owners in China has maintained a rapid growth in recent years.By the end of 2017,the number of vehicle owners in China has increased by 217 million,up 11.85%from the same period last year.But the resulting consumer complaints are also increasing,and the quality of the engine is particularly serious,so the reliability level of the engine must be improved.The reliability allocation of diesel engine is studied in this paper.By establishing and perfecting the engine reliability database system,the reliability evaluation and quality assurance system of diesel engine are constructed to improve the reliability level of diesel engine.The failure mode,influence and cause analysis(FMEA)module and interface of the reliability database system are compiled,and the results of reliability analysis are displayed intuitively by optimizing the failure mode,influence and cause analysis of the reliability database system.The logical relationship between the key steps of the reliability design of the diesel engine is analyzed.The reliability block diagram model is put forward and established,and the subsystem level and the component level of the engine are designed.It provides a basis for FMECA and reliability allocation of diesel engines.Through the reliability management system of the project group,the failure mode,influence and hazard analysis(FMECA)of the diesel engine are analyzed,and through the whole machine FMECA,the fault location,mode and cause of engine were analyzed emphatically,and the ranking of risk priority numbers was made.The reliability analysis of engine parts is carried out,the fault distribution model is established,the reliability index is determined,and the reliability level is evaluated comprehensively.Aiming at the parts with fewer fault data,the Bayesian method is proposed to estimate the model parameters.Taking exhaust pipe as an example,the reliability index of the mean time between faults(MTBF)is 48316.0891 kilometers.Based on the diesel engine reliability block diagram(RBD)modeling and the related conclusions of FMECA,the reliability allocation is carried out,and a diesel engine reliability allocation model with the minimum cost as the objective function is proposed.Genetic algorithm is used to solve the model,and the reliability increments of each subsystem are determined.A hierarchical reliability allocation model for engine components is established.A case study of lubrication system shows that the method can effectively determine the selection of relevant parts and the reliability increments of each component.It provides a basis for diesel engine design improvement,parts selection and logistics distribution.