DC fan speed control
US4856078A · kind A · utility
1,197Cited by
19References
3Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Mar 23, 1988 |
| Grant date | Aug 8, 1989 |
| Priority date | — |
| Expiry date | Mar 23, 2008 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S388/934
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A simple pulse width modulator speed control for a brushless DC "pancake" type fan motor utilizes a type 555 timer for driving a transistor switch, connected in series between the DC voltage supply and the fan motor, at about a 10 Hz rate. The duty cycle of the pulsed output of the timer is controllable by a variable resistor, which in the preferred embodiment comprises a thermistor for controlling the fan speed as a function of temperature. The fan motor is restarted on each cycle of full voltage amplitude pulses and consequently will start under all operating conditions.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.