【作者】 石学园；

【导师】 聂松林；

【作者基本信息】 华中科技大学 ， 机械电子工程， 2007， 硕士

【摘要】 与其他传动方式相比,液压传动具有独特的技术优势,其应用领域几乎囊括了国民经济各工业部门。液压系统在长期工作过程中不可避免会受到污染,各种污染物造成系统和元件工作不稳定、性能恶化,甚至于发生灾难性后果。因此,应主动采取有效措施控制液压系统污染,以降低系统的故障率和维修时间,满足国民经济各行各业对液压系统安全可靠运行的迫切要求。控制液压系统污染的首要问题是合理地设计和维护过滤系统,降低各关键点的污染度,以保证敏感元件良好的工作性能,但同时又增加了成本,因此应引入优化的思想,在性能和成本之间折衷,做出最优决策。由于在优化建模中存在许多不确定参数,因此有必要采用先进的不确定性优化理论和方法,对过滤器进行优化配置研究。本文首先总结了国内外液压系统污染控制和不确定性优化方面的最新研究成果,指出了目前研究有待解决的问题,阐述了采用优化思想和不确定性优化方法对过滤器进行配置的必要性。其次,以典型单回路液压系统为研究对象,在深入探讨污染物迁移规律和污染传递方程的基础上,以过滤系统总的设计和维护运行成本为目标函数,以敏感元件污染耐受度和过滤器纳污容量为约束条件,建立了过滤器配置的优化决策模型,并通过对假想事例的分析,阐述了模型的具体应用方法。仿真研究表明,通过多阶段混合整数非线性规划(MMINLP)方法求解模型,可以获得液压系统污染度的状态信息与过滤系统运行成本等的关系,从而对吸油路、压力油路以及回油路是否需要安装过滤器以及何时更换(清洗)滤芯做出最优决策。最后,考虑到污染物侵入/产生率、污染度、污染耐受度、过滤器纳污容量、成本参数等不确定性因素,将其表示成区间数的形式,建立了液压系统过滤器配置的不确定性优化决策模型,并提出了一种新的优化方法——含区间参数的多阶段随机混合整数线性规划(IMMILP)方法对其求解,得到了不确定情况下过滤器的优化配置方案。假想事例结果分析表明,降低污染物侵入/产生率是控制系统维护运行成本的根本措施,而过滤器优化配置是控制系统维护运行成本的重要手段。更多还原

【Abstract】 Compared with other transmission mode, hydraulic transmission has unique technical superiorities and its application fields almost include all the industrial departments of our national economy. Contamination of hydraulic system is inevitable in long-term process, and various contaminants lead to instability or performance deterioration, even disastrous consequences of hydraulic components and systems. Consequently, effective measures should be actively taken to control contamination of hydraulic system, which can reduce malfunction rate and maintenance time, satisfy the urgent request for safe and reliable operation of hydraulic systems in all departments of our national economy.The chief problem of contamination control is to design and maintain filtration system, reduce the contamination level of key points as low as possible, so as to ensure that sensitive components operate at excellent performance levels, but those also increase the cost at the same time. So ideas of optimization are introduced, compromise between performance and cost, and make optimum decision. Moreover, there are lots of uncertain parameters in optimization modeling, so the adoption of advanced optimization theory and method under uncertainty is essential to allocate filters.Firstly, the latest research results on contamination control for hydraulic system and uncertainty optimization are summarized, the problem remained to solve at present is pointed out, and the necessity of adopting optimum ideas and optimization theory under uncertainty to allocate filters is expounded. Secondly, based on throughly investigating the migration characteristics of the contaminants and contamination transfer equation in representative single-circuit hydraulic system, optimum decision-making model for allocation of the filters is established, regarding the total design and operation cost of filtration system as objective function, the contamination sensitivity of sensitive components and the dirt-holding capacity of filters as constraint conditions. Furthermore, application method of the optimization model is introduced by the analyses of hypothesis case study. Simulation results show that, the relationship between the status information of hydraulic contamination and the total operation cost of filtration system is obtained through the solution of the optimization model by multi-stage mixed integer non-linear programming (MMINLP) method, and then the optimization decisions are made on whether the filters are allocated in suction, pressure or return lines and when those filter elements should be replaced or cleaned in hydraulic system.Finally, considering uncertain factors such as contaminants intruded/generated rate, contamination level, contamination sensitivity, dirt-holding capacity of filters, parameters related to cost, integrated optimum decision-making model under uncertainty for allocation of the filters is set up in hydraulic system by expressing those uncertain factors as interval-parameter. Then a new optimization method, named interval-parameter multi-stage stochastic mixed integer linear programming (IMMILP) is employed to solve the optimized model, and the allocating schedule of hydraulic filters under uncertainty is obtained. Analyses results of hypothesis case show that, reducing contaminants intruded/generated rate is the fundamental measure to control the total operation cost of filtration system, and optimum allocation of hydraulic filters is the important means to control the total operation cost.更多还原