Research On Reliability Allocation Method Of High Pressure Common Rail System Based On TOPSIS And DFTA

The worldwide energy crisis and increasingly serious environmental pollution have made the development of aviation diesel engines with obvious economic advantages and become one of the important strategies for energy conservation and emission reduction.In order to meet increasingly stringent emission regulations,the high-pressure common rail technology of aviation diesel engines has become an important development direction of current aviation diesel engines.The high-pressure common rail system is the core subsystem of the aviation diesel engine.Whether its reliability is up to standard is directly related to whether the working task of the diesel engine can be completed.In this paper,the reliability analysis of high pressure common rail system is carried out.Based on the TOPSIS and dynamic fault tree analysis,the reliability distribution model of high pressure common rail system is established to identify the weak parts and links to be improved,thus reducing the maintenance difficulty and reducing the economic losses of high pressure common rail system caused by failures have the important guiding significance for design,manufacture and use of future aviation diesel engines.The main research contents of the thesis are as follows:(1)Explain the basic theory of reliability,and introduce the general steps of FMECA and FTA,two common methods of reliability analysis.For the structural analysis and principle analysis of the high pressure common rail system,the reliability analysis block diagram of the high pressure common rail system is drawn,and the fault analysis of the high pressure common rail system is completed.(2)The basic principle of fuzzy theory is briefly presented,and the general flow and improvement process of TOPSIS method are described.The three factors of failure mode risk are assigned and weighted,and the TOPSIS method is used to evaluate the failure mode risk value to improve the accuracy of FMECA analysis results.(3)Based on FMECA,establish a dynamic fault tree of the high-pressure common rail system,and consider the correlation analysis.A reliability functional house allocation model for the high pressure common rail system was built to identify the weak parts of the system with the distribution result.The needle valve coupler of the high pressure common rail system is determined to be a weak key component,and a simple reliability design is carried out.(4)Introduced two module identification methods.Through the modular identification of dynamic fault tree,the reliability and quantitative analysis of static modules and dynamic modules were carried out,and the reliability distribution model of dynamic systems was established by combining AGREE method.