【作者】 迟媛；

【导师】 金英子；

【作者基本信息】 东北农业大学 ， 农业机械化工程， 2002， 硕士

【摘要】 随着液压技术的发展，液压系统及液压设备越来越复杂，液压技术在农机上的应用也变得广泛而复杂，农机液压系统的故障诊断也越来越困难，液压系统的故障诊断不象机械设备那样直观，也不象电气设备那样通过万用表等仪器测得，液压系统的工作介质和工作部件都在密闭的容腔内，流量计、压力表等测量仪器远远不能满足故障诊断的需求。而由于操作者使用不当、过载、环境恶劣、老化等因素的影响极易造成农机液压设备故障。目前我国农机液压系统的管理和维护工作十分薄弱，不重视系统的原始记录和故障史的积累，不重视诊断经验的理论性总结，多数经验未形成系统资料，使诊断维护的系统性和科学性较差。所以，如何挖掘、组织、利用专家经验进行有效的故障诊断已成为当务之急。 专家系统产生于60年代中期，故障诊断专家系统从七十年代末开始研究，液压系统故障诊断专家系统近几年才有研究，都是针对某一系统进行了各种各样的探索和研究，农机液压系统故障诊断专家系统方面的研究更是寥寥无几，不能够满足农业生产的实际需要，所以建立起具有完善的推理机和庞大知识库的农机液压系统故障诊断专家系统是非常必要的。 本文总结了主要液压元件、常见农机液压系统的故障史，建立了故障诊断知识库，并针对农机液压系统故障诊断的特点研究了故障诊断专家系统，首次应用Visual BASIC6.0程序界面语言制作了故障诊断专家系统，包括系统诊断、元件诊断、专家系统诊断。其中系统诊断和元件诊断能够根据所需诊断系统(或元件)的故障现象诊断出可能的故障原因或部位，再根据找到的部位查得故障的排除方法；专家系统诊断采用了人机交互式界面、产生式规则表示法、故障树的诊断模型、深度优先搜索法和正向推理策略。农机液压设备的使用者可根据观察的故障现象，通过本软件的诊断达到排除故障的目的。本系统搜集了大量的农机液压系统的故障信息，具有很高的使用价值，首次实现了专家系统在多种农机液压系统及其元件故障诊断中的应用。 本文对农机液压系统故障诊断专家系统的进一步研究提供了基础，并提高了农机液压系统的故障诊断的效率和准确性，对于提高农机液压设备的使用率具有重要的现实意义。更多还原

【Abstract】 With the deveIopment of hydraulic technology, hydraulic system and hydraulicequipment are more complicated, hydraulic technology is more widely and morecomp1icatedly used in agricultural machine and their malfunction is more difficu1t to bedetected. Fault diagnosis of hydraulic system is not as apt to be observed as that of themechanical equipmeflt or is not as easy to be detected as that of electric equipmeflt bymu1tipurpose meter or other meters. Flux meter gage and pressure gage can’t meet the needof fault diagnosis for hydraulic system because its working medium and workingcomponents are hiding inside the sealed vessel. At the same time hydraulic system inagricultural machine is apt to have malfunction because the users operate by mistake,overloading, bad working environment or aging. At present, the administration andmaintenance of hydraulic system in agricultural machine are very weak. The accumulationof the original fauIt record and the historicaI fault record is neglected. The theoreticalsummary of the diagnostic experience is neglected. Most of the experience is not tUrnedinto systematic written materials that make the diagnosis and maintenance have littlesystematic science in them. How to excavate, arrange and take the advantage of theexperience of the experts to make efficieflt diagnosis is imperative fOr us now.This thesis summarizes the fault histories of major hydraulic components and commonagricultural mechanical hydraulic system, builds knowledge database, stUdies on theoff line expert system for fault diagnosis of hydraulic system in agricultUral machine andmakes a expert system compiled in Visual BASIC fOr hydraulic fault including systemdiagnosis, components diagnosis and expert diagnosis. System diagnosis and componentSdiagnosis can query the fault cause or fault place according to the visible fault phenomenaand can query the solving methods according to the cause and the place. Expert systemdiagnosis adopts man-computer dialog pIatform, producing method, fault tree analysis andfOrward chaining. The user of hydrauIic equipment can eliminate the malfunction by thediagnosis of the software according to the visible phenomena. Because this systemaccumulates a good deal of fault message of hydraulic system in agricultUral machine, it hashighly value for users. It begins to realize that expert system is used in many hydrauiicsystem and components.This thesis provides the base for the further stUdying on expert system of hydraulic faultdiagnosis and enhances the efficiency and accuracy for hydraulic fault diagnosis inagricultural machine. It is significant to improve the efficiency of using hydraulic system in1lagricultural machine.Master Candidate: Chi Yuan Major: Agricultural Mechanization Supervisor: Associate Prof. Jin Yingzi更多还原