US5197858A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Thermal control variable speed DC brushless fan
Assignee: Delta Electronics Inc
•
Filing: 1991-10-23
•
Granted: 1993-03-30
•
Expires: 2011-10-23
Abstract
Abstract A thermal control variable speed DC brushless fan, especially a DC brushless fan which may change speed in accordance with the temperature sensed, includes a fan speed control circuit and a DC brushless fan. The fan speed control circuit is composed of drive ICs, operation amplifiers, transistors, diodes, capacitors resistors, and a thermal sensor. Under normal conditions, the change in the fan's rotation speed relation to the temperature is almost linear, but when the thermal sensor is open or shorted the speed control circuit of the fan causes the fan to operate at full speed to maintain a cooling effect.
Inventors
- 👤 Rex Cheng
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 22:44
CPC Classifications
F; F04; F04D; F04D27/00; F04D27/004; Y; Y02; Y02B; Y02B30/00; Y02B30/70; Y10; Y10S; Y10S388/00; Y10S388/923; Y10S388/934
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
58 words
A variable speed fan, comprising: an impeller; a thermal sensor; means responsive to the thermal sensor for rotating the impeller at a speed which varies in response to changes in temperature sensed by the sensor; means for detecting a malfunction in the sensor; means for causing high-speed operation of the fan in response to detection of the malfunction.
Claim 2
Dependent Claim
58 words
A variable speed fan, comprising: an impeller; a thermal sensor; means responsive to the thermal sensor for rotating the impeller at a speed which varies in response to changes in temperature sensed by the sensor; means for detecting a malfunction in the sensor; means for causing high-speed operation of the fan in response to detection of the malfunction.
Claim 3
Dependent Claim
25 words
A variable speed fan as claimed in claim 1, wherein the thermal sensor is provided on the fan to thereby sense temperature adjacent the fan.
Claim 4
Dependent Claim
23 words
A variable speed fan as claimed in claim 1, wherein said thermal sensor is positioned away from the fan to sense ambient temperature.
Claim 5
Dependent Claim
58 words
A variable speed fan as claimed in claim 1, wherein said impeller rotation means comprises a pulse-driven DC brushless motor and a motor speed control circuit, the speed at which the motor is driven being varied in response to changes in a voltage drop across the thermal sensor caused by temperature-related changes in a resistance of the sensor.
Claim 6
Dependent Claim
52 words
A variable speed fan as claimed in claim 4, wherein said malfunction detection means comprises a circuit arranged to output a signal to said motor speed control circuit in response to a change in said voltage drop which indicates a malfunction, said signal causing said speed to increase to a maximum speed.
Claim 7
Dependent Claim
25 words
A variable speed fan as claimed in claim 1, further comprising means for maintaining a minimum speed when the temperature drops below a predetermined level.
Claim 8
Dependent Claim
112 words
A variable speed fan as claimed in claim 6, wherein said impeller rotation means comprises a pulse-driven DC brushless motor and a motor speed control circuit, the speed at which the motor is driven being varied in response to changes in a voltage drop across the thermal sensor caused by temperature-related changes in a resistance of the sensor, and wherein said minimum speed maintaining means comprises a circuit arranged to output a signal to said motor speed control circuit in response to a change in said voltage drop which indicates a predetermined temperature has been reached, said signal causing said speed to be maintained until the temperature rises above the minimum temperature.
References Cited (Backward Citations)
US3544236A
Cited
US4535275A
Cited
US4806832A
Cited
US4506199A
Cited
US4644238A
Cited
US4609854A
Cited
US4722669A
Cited
US4620139A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-03-29 | 1996-09-28 | 1997-03-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-03-29 | 2000-09-28 | 2001-03-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-03-29 | 2004-09-28 | 2005-03-30 | $7700.00 | Window Closed / Lapsed |