Shaft rotation monitoring apparatus
US5103213A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 25, 1990 |
| Grant date | Apr 7, 1992 |
| Priority date | — |
| Expiry date | Jun 25, 2010 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01P1/106
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A photo-optical coupler is connected to a shaft to provide a series of electronic pulses at a frequency corresponding to rotational velocity of the shaft. Apparatus electronics is responsive to frequency of such pulses for indicating a low speed alarm condition when such frequency is below a preselected threshold. The apparatus electronics includes a digital counter that is set to a first preselected count upon occurrence of each of the shaft rotation pulses, and which is thereafter decremented between the shaft rotation pulses. A low speed alarm condition is indicated if the counter reaches a count of zero prior to a succeeding shaft rotation pulse. In the preferred embodiment, the counter is decremented by an oscillator having a clock frequency coordinated with the first preselected count so as to activate the alarm when rotational velocity of the shaft decreases to a predetermined threshold percentage of a nominal rotational velocity of the shaft.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.