Abstract: Making use of the photo-electricity sensor and 80C51 single chip microcomputer，an on-line monitor system which could monitor the hydraulic oil contamination timely and correctly was designed，and lots of experiments were accomplished.With test data collected and processed，the results indicate that the system can show a correct grade of hydraulic oil contamination and may warn once the hydraulic oil contamination exceeds the permission limits．It is one of the most valid methods of monitoring the engineering hydraulic oil contamination in time．The study results have theoretical signification and could be used in the steering system of engineering machine.

Key words: hydraulic oil contamination, on-line monitor system, microcomputer technique, photo-electricity sensor, trouble diagnose

摘要： 用光电传感器、80C51单片机等元件，设计了工程机械液压油污染度在线监测系统．通过实验室试验，进行了数 据采集、处理和分析．结果表明，该系统能够准确显示液压油污染度等级，具有超限报警功能，达到了对工程机械液 压系统油液污染进行实时监测之目的，是预防和早期诊断液压系统故障的有效方法之一．

关键词: 油液污染度, 在线监测系统, 单片机技术, 光电传感器, 故障诊断