Differential oil pressure control apparatus and method
US6237420A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 14, 1999 |
| Grant date | May 29, 2001 |
| Priority date | — |
| Expiry date | Apr 14, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG05B9/02
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A microprocessor based control for monitoring oil pressure of compressors can use a normally open or a normally closed pressure switch (S1, S2) and LED indicator (LED1) having a diode isolated power supply (VDD.sub.- SENSOR) separate from the power supply (VDD) of the microprocessor (U1). Timing of the microprocessor is derived from the frequency of the line (60 Hz). The microprocessor is normally in a sleep mode and is awakened by each 60 Hz interrupt to check the condition of the pressure switch, the accumulated time that inadequate pressure has occurred and whether the relay needs to be energized and then returns to the sleep mode. The resulting reduced power requirement enables extended retention of accumulated "bad" oil time. Since oil pressure does not build-up to a satisfactory level for the first eight seconds or so upon start-up, the microprocessor senses whether the oil pressure indicates good oil immediately upon start-up which indicates a fault condition and if so will shut the system down but only after approximately four seconds which allows the compressor to be jogged, or momentarily energized, to force refrigerant out of the compressor and into the system, which is …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.