“间接”的含义是:机器转速、工作温度和其它因素(如载荷、驾驶模式、道路状况等)决定着油液降解程度或换油期,根据机器工作参数与油液质量状态之间的统计关系(或计算机模型),通过监控机器工作参数可以判定油液降解状态,确定是否需要更换油液。通用汽车公司(GM)开发的“油液寿命系统(Oil Life System)”和克勒斯莱汽车公司(DaimlerChrysler AG)与壳牌石油公司(Shell)联合开发的“主动服务系统(ASSYST system或Flexible Service System)”是间接灵活型换油期技术的典型代表。
MOA是一种机器状态监控概念和维修工具。与传统油液分析信息反映新油液(静态)质量属性不同,机器油液分析信息反映在用油液(动态)质量水平。MOA包含两个功能层次:(1)机器油液状态诊断,即确定油液的“洁净、干燥和健康(clean,dry,healthy)”状态或其“质量、碎片或元素(quality,debris or elemental)”,执行此功能需要实施三维机器油液分析:机器磨损,系统污染和油液化学。(2)机器油液状态预报,即根据机器油液状态的数字化信息与目标极限或老化极限(主动性维修),变化极限或统计极限(预防性维修)的比较分析,提出实施机器维修管理和油液维护管理的行动建议。
嵌入式和在线式机器油液分析仪器或系统具有实时(real-time,包括true real time和near real time,真实时系统直接置于系统油路中进行连续实时诊断,近实时系统实际上是将机器油液分析实验室程序移至现场进行快速分析)功能,使用便携式分析仪器(portable kit)的机器油液分析是在设备现场(on-site)或车间(in-shop)进行的,分析精度和准确度低于非现场机器油液分析实验室,主要用于现场快速判定机器油液质量状态,确定“临界”油液样品并将其送至基本配置(通常包括原子光谱仪、红外光谱仪、粘度计和黑色金属密度测定仪或铁谱仪)或完全配置(基本配置仪器和油液理化性质分析仪器,如TAN/TBN滴定仪,KF水分析仪)的非现场机器油液分析实验室进行全面和准确分析。
美国国防部陆军油液分析计划(AOAP)通过对油液进行定期分析,致力于检测机器零件的潜在失效和确定油液的质量状态,是陆军在编全部航空和非航空设备的必须的维修服务手段。便携式或随行式油液状态监控技术能够提高AOAP的能力,快速为用户提供分析结果,因此能够达到AOAP“强化系统管理,减少维修停工,避免发动机、传动和液压系统重大失效”的目标。为了确定是否存在商品化或处于开发状态的便携式和在线式油液分析技术与仪器,美军陆军坦克汽车司令部(US Army TACOM)坦克汽车研究开发与工程中心(TARDEC)所属的石油与水质量技术小组(PWQTT)对美国34家油液分析技术开发/仪器制造商的44种油液分析技术与仪器进行了市场调研,于1999年5月发表了题为“油液分析仪器市场调研”的报告”。
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Concepts and Techniques of Smart Machine System
Based on Machinery Oil Diagnostics and Prognostics
Li Shenghua Jin Yuansheng Chen Darong
State Key Laboratory of Tribology, Beijing 100084, China
Email: lish@pim.tsinghua.edu.cn
Abstract A concept of Smart Machine System Based on Oil Diagnostics and Prognostics has been suggested based on the progress of machinery condition monitoring and instrument manufacturing technologies, as well as the development of installations and orientations of both commercial and military oil analysis laboratories. The technological features of the system are embodied in: (1) the hardware system either consists of an integrated assembly of independently operated and function-specific smart sensors (Future technology of MOA), or is itself an on-board machinery oil diagnostics and prognostics combined from function-specific analysis modular (Current technology of MOA). The system performs comprehensive analysis of three-dimensional machinery oil vectors ---- machinery wear, oil chemistry and system contamination for real time monitoring of machinery operation and oil condition, and (2) the software system is an expert system with fuzzy logics and artificial neural network as its algorithm and reasoning for coordinated management of machinery operation and oil application. Smart machinery oil diagnostic and prognostic systems distinguish themselves with traditional oil analysis laboratories in the following of their features: (1) smaller size, lower weight, easier operability, and more executable capabilities of data analysis and maintenance strategy, which can thus best meet the technical needs of both commercial real-time MOA and military on-board MOA, and (2) more real-time without sampling, delivering and wasted oil disposal, and both machine operators and oil users can, in direct manners and at any moment, acquire oil condition information and take managerial measures and maintenance actions with the expert recommendations yielded from the MOA software. Specifically all analysis results can be uploaded via network systems to remote addresses. The commercial and military potentials of such a system can be well expected in: (1) establishing smart machinery system based on on-board machinery oil diagnostics and prognostics, and (2) developing e-machinery oil diagnostic and prognostic systems characteristic of digital machinery oil analysis and based on network technologies.
Keywords: Machinery oil diagnostics and prognostics, Smart machinery system, Machinery condition monitoring, Machinery maintenance, Oil application and management.