Capacitive liquid level sensor with integrated pollutant film detection
US6073488A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 10, 1998 |
| Grant date | Jun 13, 2000 |
| Priority date | — |
| Expiry date | Dec 10, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01F23/268
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The subject matter of the present invention is a method and a device for capacitive liquid level measurement which are particularly suitable for determining liquid level between adhesive media 10, 11 of different conductivity. The known sensor principle is based on the fact that the environmentally dependent capacitance is measured between neighboring electrodes 13, 4; 4, 5; 5, 6 of a rod-shaped probe 1. According to the invention, the probe 1 has electrodes 4, 5, 6, 13 with covers 7 of different thicknesses d.sub.i. The effective thickness d.sub.s /.epsilon..sub.s of an insulating pollutant film 14 can then be determined by capacitance measurements between at least two pairs of electrodes 4, 5, 6, 13. The influence of a conductive pollutant film 14 on the capacitance signal can be eliminated by selection of at least one suitable measuring frequency. Furthermore, by optimizing the electrode height h, a large capacitance jump is achieved for a digital liquid level display, and/or a largely continuous increase in capacitance is achieved for an analog liquid level display. The sensor is preferably used to determine the location of an interface 12 between water 10 and oil 11 in a separ…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.