Low oil detector with automatic reset
US5765994A · kind A · utility
Inventor
Key dates
| Filing date | Jul 14, 1995 |
| Grant date | Jun 16, 1998 |
| Priority date | — |
| Expiry date | Jul 14, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/552
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An optical liquid level sensor for distinguishing between the presence of oil and vapor within a compressor crankcase. The sensor has a light transmitting window positioned to interface the crankcase interior and a planar side facing the crankcase exterior. A light source and a light sensor are both positioned adjacent the exterior face of the window. The sensor has a first condition when the prismatic face is immersed in oil and a second condition when the prismatic face is immersed in vapor. An electronic circuit having a dual MOSFET switch for alternating current is mounted adjacent the light source and sensor. The circuit provides power to the source and monitors the sensor. When the sensor is in the first condition, the circuit closes the switch. When the sensor detects the second condition, the circuit starts a timer and continuously tests the condition of the sensor. If the first condition is detected, the timer resets to its initial value. If the second condition continues for the full time period, the circuit opens the switch. On the opening of the switch, the circuit continuously tests for the condition of the sensor. If the sensor returns to the first condition, the circ…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.