飞机发动机的异常摩擦、磨损会在滑油中产生大量的磨粒，对滑油磨粒的有效检测可以为发动机的故障诊断提供可靠信息。设计了一个弧状极板式电容传感器，但传感器中电容变化量非常小，传统方法难以检测，采用交流电桥式电容检测方法。系统以AD9833为DDS信号发生器给交流电桥施加激励信号，经C/V转换、差分放大、相敏解调以及低通滤波等处理后得到实时电压变化。可实现弱信号的精确检测，且能有效克服杂散电容和寄生电容的影响。多次实验结果均表明：该检测系统具有灵敏度高，稳定性好等特点。%The abnormal friction and abrasion of aircraft engine will produce a large amount of abrasive particles in lubricating oil,effective detection of lubricating oil abrasive particles can provide reliable information for engine fault diagnosis. An arc plate capacitance sensor is designed,but the capacitance change of sensor is very small,it is difficult to detect with traditional method,alternating current bridge capacitance detection method is used here. The system takes the AD9833 as DDS signal generator to exert pumping signal on alternating current bridge,by C/V conversion,differential amplifier,phase sensitive demodulation and low pass filtering obtain real time change of voltage. The design can realize accurate detection of weak signal,and it can overcome influence of stray capacitance and parasitic capacitance effectively. Multiple experimental results show that the system has characteristics of high sensitivity and good stability.
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