Capacitive Oil Sensor Design Based On Dielectric Constant

Lubricating oil with lubrication, cooling effect, etc, is widely used in vehicles and other large machinery and equipment. Its quality directly determined the performance and service life of industrial equipment. Therefore, it is necessary to develop a real-time monitoring system to understand the lubricating oil usage, to judge its quality is qualified or not.If it is not qualified, we should change it in time.The technology of oil research at home and abroad has been analyzed, designed the real-time monitoring system of oil with CAN bus. First of all, according to the requirement of design of a cylindrical capacitance sensor, analysis and probe suitable electrode materialand insulation material selection, structure size to edge effect for probe was determined by theoretical analysis and key points of the ANS YS magnetic field simulation of two kinds of means. And then it analyzes and compares several commonly used capacitance detection circuit, the final choice of CDC technology based on integrated chip AD7745 as the core components of capacitance acquisition module. The hardware circuit module selects the enhanced 51 MCU STC12C2052 as the control chip, design the circuit and CAN communication circuit capacitance acquisition conversion based on AD7745. Next, I2C communication, SPI communication, CAN communication and the interface of LabVIEW software programming realization based on the hardware circuit. Capacitance sensor and the standard oil was prepared in the end, an experimental platform is built to do the calibration, sensor, and the test system has done a comprehensive experiment. The results show that, the system can be realized on the oil dielectric constant and temperature at the same time monitoring, measurement of the dielectric constant is 1-6.