Direct current motor speed controller
US5313548A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 22, 1993 |
| Grant date | May 17, 1994 |
| Priority date | — |
| Expiry date | Apr 22, 2013 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S261/26
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A fire-fighting system in which a liquid chemical foamant is introduced into the water stream in varying amounts so as to maintain a predetermined percentage mixture irrespective of variations in the water flow includes a motor-driven pump where the motor is controlled over a first speed range by pulse width modulating the drive to the motor and over a second speed range, producing intermittent motion, by burst width modulating the drive signal when it is operating at its minimum pulse width modulated duty cycle. Using this technique the range of available motor speeds is extended well beyond that which can be achieved using pulse width modulation of the motor drive signal alone.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.