CAPACITIVE OIL DETERIORATION AND CONTAMINATION SENSOR

摘要

An oil deterioration and contamination sensor (10) includes a housing (14), a substrate (24) with a first capacitive plate (30) mounted within the housing (14), a second capacitive plate (34) mounted to the housi ng (14) close to the first capacitive plate (30), and a total reference capacitor which includes an external fixed reference capacitor (58 ). The second capacitive plate (34) is mounted to the housing (14) such that a mixed fluid including oil freely circulates within a gap (4 0) between the first and second capacitive plates (30, 34) thereby defining an oil deterioration and contamination sensor capacitor. The respective capacitances of the oil deterioration and contamination capacitor and the total reference capacitor provide an indication of a dielectric constant of the mixed fluid including oil within the gap (40). The sensor (10) includes circuitry to indicate when dielectric constant exceeds a predetermined value or exceeds a predetermined value at a rate of dielectric constant change in excess of a maximum ordinary rate of oil dielectric constant change.