Liquid level sensor
US4924702A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 10, 1989 |
| Grant date | May 15, 1990 |
| Priority date | — |
| Expiry date | Mar 10, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01F23/268
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A capacitive sensor is constructed to eliminate electrical conduction through a liquid being measured. The electrical conduction in the liquid occurs between the plates of the reference and measuring capacitors. The capacitive plates which are spaced from the common capacitive plate to form the reference and measuring capacitors are of unitary construction and formed from anodized aluminum. The anodization forms an insulated surface which prevents conduction between the electrodes through the liquid. A ratio taken between the measuring capacitor and reference capacitor is therefore indicative of the level of the liquid within the gap of the measuring capacitor and is independent of the conductance of the liquid and its dielectric constant. Such a probe is particularly useful in applications where the liquid undergoes indeterminable changes in conductivity such as a lubricant which becomes contaminated by metallic particulates.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.