【作者】 胡滨；

【导师】 聂松林；

【作者基本信息】 华中科技大学 ， 机械电子工程， 2008， 硕士

【摘要】 控制液压系统污染的关键问题之一是合理地设计和维护过滤系统,降低各关键点的污染度,但势必会增加系统成本。通过引入优化的思想,达到系统性能和成本之间的折衷,从而制定最优决策是非常必要的。由于在优化建模中存在许多模糊、不确定的参数,采用模糊的不确定性优化理论和方法对过滤器进行优化配置研究具有十分重要的意义。本文首先总结了国内外液压系统污染控制和模糊优化方法方面的研究成果,阐述了采用优化思想和模糊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,在考虑诸多模糊参数的情况下,建立了基于模糊参数的整数线性规划(FPILP)方法的液压系统过滤器配置决策模型,并将FPILP方法所求得的结果与确定性及区间参数规划方法进行了对比和分析。本文将诸多不确定性参数表示成区间模糊数的形式,建立了基于区间模糊整数线性规划(IFILP)和区间模糊二次整数线性规划(IFQILP)方法的液压系统过滤器配置决策模型。将FPILP、IFILP和IFQILP方法分别求得的最优解从理论上进行了对比和分析研究。研究结果表明(a)在污染物侵入/产生率水平为重度时模糊优化能够有效降低系统成本最优值;(b)同时设置吸油路和回油路过滤器能够以最低的成本降低系统污染度,但当污染物侵入/产生率水平为重度时有较大的风险性;相比较而言,此时同时设置吸油路和压力油路过滤器能够有效降低液压系统污染度,取得更好的过滤效果;(c)虽然IFILP方法使系统成本最优值较低,但区间模糊因子为1,即各过滤器的纳垢容量约束为紧约束,故IFILP方法的经济性是以牺牲设计风险为代价的;虽然IFQILP方法增大了系统成本最优值,缩短了过滤器滤芯更换周期,但各关键点区间模糊因子均为零,即在系统成本和设计风险间达到了良好的折衷。最后,考虑到实际问题的需要,设计了一套典型单回路液压污染采样测试主系统、液压污染采样测试系统采样设备和液压污染采样测试注入系统,并制定了液压污染采样测试系统的试验步骤和方法。该系统能够达到有效控制液压系统内部污染循环、测定液压系统污染度的要求。更多还原

【Abstract】 One of the key problems of hydraulic contamination control is to design and maintain filtration system reasonably reducing the contamination level of key points as low as possible. However, those measures also will increase the system cost at the same time. It is essential that optimization theory should be employed to help making a compromise between system performance and cost, and then the optimum decision will be obtained. Owing to the existence of fuzzy, uncertain parameters in optimization model, it is of importance that planning research would be conducted on the allocation of system filters by means of advanced fuzzy optimization theory and method under uncertainty.Firstly, the latest research on contamination control for hydraulic system and fuzzy optimization are summarized and the necessity of adopting optimum ideas and fuzzy optimization theory to allocate filters is expounded. Secondly, considering lots of fuzzy factors in representative single-circuit hydraulic system,optimum decision-making model for allocation of the filters is established including lots of fuzzy factors by fuzzy-parameter integer linear programming (FPILP). Furthermore, comparison results are made among fuzzy, certain and interval methods.Considering many interval fuzzy parameters,optimum decision-making model for allocation of the filters is established by interval-fuzzy integer linear programming(IFILP)and interval-fuzzy quadratic integer linear programming(IFQILP), and comparisons for the optimized solutions are made among FPILP, IFILP and IFQILP. The results show that (a) fuzzy optimization method can reduce the total design and operation cost of filtration system effectively when contaminants intruded/generated rate is high; (b) Allocating both suction and replace filters can reduce contamination level with the lowest cost, however, may take more risk when contaminants intruded/generated rate is high; Instead, allocating both suction and pressure filters can reduce contamination level and take favorable filtration effect; (c) Although IFILP reduces the total design and operation cost of filtration system, but interval fuzzy factor amount to one, in other words, each filter’s contaminant retaining capacity constraint is tight, so good economy performance of IFILP is at the expense of high failure risk; correspondingly, although IFQILP increases the total design and operation cost of filtration system, shortens the replacing periods of filters, but interval fuzzy factor in each key position amount to mothing, in other words, IFQILP can make a satisfying balance between the system cost and risk.Finally, considering the demand for real-world problems, a main sampling examination system, sampling device and contamination injecting system for contamination control in the typical single-circuit hydraulic system are designed, and examination step and criterion are also constituted. And this system can be employed to control the contamination level in the inner circulation of the hydraulic system and helps to measure the value of the contamination level accurately.更多还原