基于环状电极的电容式润滑油磨粒检测系统设计

摩擦副非正常磨损时将产生直径为几十微米的大金属磨粒。采用阻抗类方法检测磨粒时,要求传感器具有较高的灵敏度。为此,设计了差分结构的环状极板电容式传感器。应用电容/数字转换芯片AD7746将传感器的输出直接转换为数字信号,省去了前端复杂的信号调理电路,简化了设计,并且有效地降低了寄生电容和杂散电容的影响。实验表明:系统分辨率可以达到0.125 fF,极大提高了系统灵敏度。

Design of capacitance lubricating oil grains detecting system based on ring electrode

In abnormal operation, friction pair will produce large metal wear debris about tens of micron in size. When the impedance method is used to detect grains, very high sensitivity is necessary. So, a ring electrode capacitive sensor with a differential structure is designed. By replacing the complex signal processing circuit, capacitance-to-digital converter AD7746 is used to convert capacitance sensor output into digital signal directly, simplifying the electronics, and minimizing the interference of distributed and parasitic capacitance. Experiment result shows that the system has high sensitivity with resolution of 0. 125 fF.