Capacitive particle sensor
US5668309A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 31, 1995 |
| Grant date | Sep 16, 1997 |
| Priority date | — |
| Expiry date | Aug 31, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N27/24
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An apparatus for detecting particles within a hydraulic system having a hydraulic line includes a capacitor formed by a pair of electrodes. A charging circuit produces a charging current of constant magnitude. The charging current is used to charge the capacitor to a predetermined voltage. A timing circuit measures the elapsed time between the time at which the charging circuit begins to produce the charging current and the time at which the capacitor has been charged to the predetermined voltage. The timing circuit produces a pulse width modulated signal. The magnitude of the pulse width modulated signal is indicative of the time difference. A controller receives the pulse width modulated signal and detects particles by comparing the duration of each pulse with a reference pulse.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.