Study On Maintenance Policy Of City Bus Based On Reliability And Economy

Taking the optimization of city bus maintenance policy as research object and aiming at minimizing the upkeep of bus corporation, the thesis studies the national rule of law,industry standard and corporation criteria related with bus maintenance, and researches the data statistic and coding of field fault of bus, the identfication way of key subassembly,key assembly or key system, field reliabity modeling, maintenance model and maintenance characteristic, the reliability- baseed bus maintenan modeling, the optimization scheme and arithmetic of bus maintenance policy as well as the validity analysis of the reliability- based bus maintenan modeling and the optimization scheme and arithmetic.The thesis briefs the corporation criteria of city bus maintenance, and make the data pretreat of bus field failure, the fault harm sort and fault coding. The equivalent failure rate statistics and comparison of subassembly and assembly of 22 giant gas passenger bus and 25 giant diesel bus are done. The equivalent failure rate is used to quantify the hazard degree and to identify the key subassembly, key assembly or key system. These work laid the foundation of field reliability modeling, reliability-centered maintenance modeling and maintenance policy optimization.It is studied that how to set up the statistical distribution model of field reliability based on the data statistic of field fault of city buses. In this paper, the basic reliability functions and their relations, the graph of failure rate function are studied,and 6 types of Weibull distribution models often used in the analysis of reliability are introduced, and the way to set up the statistical distribution model of field reliability, the calculation of goodness of fit indicator and the comparison of fit goodness of different distribution functions, theχ2 fit checkup are studied as well. For the first time, it is done to entirely set up the statistical distribution model of field reliability of 41 key subassemblies or key assemblies of gas bus. The shape characteristics and classifying of graphes of failure rate functiones of 41 key subassemblies or key assemblies of gas bus are analysed and discussed. And the corresponding maintenance policy is analysed and discussed, too. They are the groundwork of the research on reliability and maintenance policy optimization of city bus.In this paper, the technical characteristics and application scopes of all kinds of maintenance wayes are studied. And the change rules of field reliability, the related upkeep models and usability models in all kinds of maintenance models are analized, too. The existence condition of the most economical maintenance policy, the maintenance characteristics, the equivalent between the usability restriction and economical efficiency restriction are researched as well. The thesis gives a particular description of reliability-based maintenance model, the way of bus maintenance policy optimization and the programming process of preventible maintenance (i.e. PM). For the first time, field reliability-based maintenance model is set up. And for the first time, the model of city bus maintenance policy optimization based on field reliability maintenance model is built up. And it is also for the first time that, based on field reliability maintenance model, the maintenance policy optimization of main subassemblies or key parts of city bus is done. At last, the validity and feasibility of the reliability-centered maintenance model and the way of maintenance policy optimization being put forward are studied at some length.On the premise of ensuring vehicle reliability, taking the optimization of bus maintenance policy as research object, the thesis integrates the maximization of vehicle usability with the minimum of total upkeep. The research results are of great importance in tems of theoretical significance, academic worth and engineering practical value, and they are of certain significance to improve maintenance management level and increase maintenance cost efficiency. The reliability-centered maintenance model and the method of maintenance policy optimization are provided with wider popularization worth, and can be used in the analysis of maintenance policy optimization of general mechanical parts.