| 摘要 |
PURPOSE:To obtain an alarm device of oil contamination having no malfunction, by immersing an electrostatic capacity sensor provided with electrodes opposing at the center of an insulating member shielded electrostatically each other in a lubricating oil of an engine and detecting an increase of the electrostatic capacity. CONSTITUTION:A sensor for electrostatic capacity detection 1 is formed by electrostatically shielding the circumference of a cylindrical insulating material 2 by a shielding material 3 and a crevice 4 in a diameter direction is formed at the center. Electrode plates 5a, 5b are buried on both sides of the crevice 4 and lead wires 6a, 6b are connected with the plates 5a, 5b. The sensor 1 made by said process is immersed in oil to be detected the contamination and the oil having a fixed thickness is circulated in the crevice 4. The wires 6a, 6b of the sensor 1 are connected with e.g. an oscillator 7 and the variation of the electrostatic capacity of the sensor 1 more than a fixed value is outputted from a comparator 9 through an LPF8 by varying the frequency of an oscillation signal and then, an alarm of oil contamination having no malfunction can be given. |
