Apparatus and method for monitoring liquid levels
US4859987A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 11, 1987 |
| Grant date | Aug 22, 1989 |
| Priority date | — |
| Expiry date | Dec 11, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01F23/804
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An apparatus to indicate a low level of liquid in a vessel, such as an automobile crankcase. A light-emitting diode and a phototransistor are coupled at the crankcase so that the light received by the phototransistor varies with rising or falling oil levels. The diode has a given maximum current rating. A unique pulse generating circuit applies a short duration, high-current pulse to the light-emitting diode to produce a correspondingly short but intense burst of radiant energy that is received by the phototransistor. The sensitivity of response is superior to that of a phototransistor employed with a light-emitting diode driven by low-level voltages giving rise to currents equal to or less than its steady-state rating. False readings are eliminated when the vehicle is on an incline, or when the ignition switch is improperly operated. Reliable functioning is had, even at high operating temperatures.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.