Research On Application Of Fuzzy-Parameter Optimization In Contamination Control For Hydraulic Systems

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.