Series fan speed control system

• US 6,396,688 B1
• Filed: 03/29/2000
• Issued: 05/28/2002
• Est. Priority Date: 03/29/2000
• Status: Expired due to Term

• Current Assignee: Dell Products LP (Dell Technologies Inc.)
• Original Assignee: Dell Products LP (Dell Technologies Inc.)
• Inventors: Davies, Stephen J., Bobbitt, Jil M., Tunnell, Jason D.
• Primary Examiner(s): Han, Jessica
• Assistant Examiner(s): TIBBITS, PIA FLORENCE
• Application Number:
  US09/537,159
• Time in Patent Office: 790 Days
• Field of Search: 361/687,51
• US Class Current: 361/679.48
• CPC Class Codes: G06F 1/20 Cooling means
• CPC Class Codes: G06F 1/206 comprising thermal management
• CPC Class Codes: H05K 7/20836 Thermal management, e.g. server temperature control

Abstract

A redundant fan system includes an in-series configuration of adjustable speed fans. A speed controller coupled to the fan system includes a first fan operated at a constant operating speed and a second fan operated at an adjusted operating speed to maintain a speed differential between the first and second fan speeds. A sensing device is connected to the first and second fans and to the speed controller for maintaining the speed differential constant.

Claims

1. A cooling system for an electronic device, comprising:

a first fan for moving a stream of air;

a second fan mounted adjacent the first fan for moving the stream of air;

a constant speed controller electrically connected to one of the first and second fans;

an adjustable speed controller including a first speed sensing device and a voltage controller electrically connected to one of the first and second fans, and a second speed sensing device electrically connected to the other of the first and second fans; and

a speed differential between the first and second fans being maintained in response to adjusting voltage supplied to one of the first and second fans such that one of the fans, being in an upstream position relative to the stream of air, is speed adjusted to a speed level higher than the other of the fans.

2. The system of claim 1 wherein the first fan is in an upstream position and the second fan is in a downstream position relative to the stream of air.

3. The system of claim 2 wherein the constant speed controller is connected to the second fan.

4. The system of claim 2 wherein the first fan is adjusted to operate at a second substantially constant operating speed in response to the second fan becoming inoperable, the second constant operating speed being a higher speed than a first constant operating speed.

5. The system of claim 4 wherein the first constant operating speed is approximately one-half of the second constant operating speed.

6. The system of claim 3 wherein the first speed sensing device and the voltage controller are connected to the first fan, and the second speed sensing device is connected to the second fan.

7. The system of claim 6 wherein the first fan is speed adjusted to a speed level higher than the constant speed of the second fan.

8. The system in claim 1 wherein the first fan is in a downstream position and the second fan is in an upstream position relative to the stream of air.

9. The system of claim 8 wherein the constant speed controller is connected to the first fan.

10. The system of claim 8 wherein the second fan is adjusted to operate at a second substantially constant operating speed in response to the first fan becoming inoperable, the second constant operating speed being higher than the first constant operating speed.

11. The system of claim 10, wherein the first constant operating speed is approximately one-half of the second constant operating speed.

12. The system of claim 9 wherein the first speed sensing device and the voltage controller are connected to the second fan, and the second speed sensing device is connected to the first fan.

13. The system of claim 12 wherein the second fan speed is adjusted to a speed level higher than the constant speed of the first fan.

14. The system of claim 1 wherein the speed differential is approximately 3%.

15. The system of claim 1 wherein the speed differential is between about 2% and about 10%.

16. The system of claim 1 wherein the first fan and the second fan are positioned to direct the stream of air in a common air flow direction along a common airflow axis.

17. The system of claim 1, further comprising:

a fan housing having the fans removably mounted in a side-by-side series configuration therein.

18. A computer system comprising:

a chassis;

a microprocessor mounted on the chassis;

a system memory coupled to provide storage to facilitate execution of computer programs by the microprocessor;

an input coupled to provide input to the microprocessor;

a display coupled to a video controller;

a mass storage coupled to the microprocessor;

a first fan mounted in the chassis for moving a stream of air;

a second fan mounted adjacent the first fan for moving the stream of air;

a constant speed controller electrically connected to one of the first and second fans;

an adjustable speed controller including a first speed sensing device and a voltage controller electrically connected to one of the first and second fans, and a second speed sensing device electrically connected to the other of the first and second fans; and

a speed differential between the first and second fans being maintained in response to adjusting voltage supplied to one of the first and second fans such that one of the fans, being in an upstream position relative to the stream of air, is speed adjusted to a speed level higher than the other of the fans.

19. A method of operating a plurality of series mounted fans, comprising:

mounting a first in a chassis for moving a stream of air;

mounting a second fan adjacent the first fan for moving the stream of air;

electrically connecting a constant speed controller to one of the first and second fans;

electrically connecting an adjustable speed controller including a first speed sensing device and a voltage controller to one of the first and second fans, and electrically connecting a second speed sensing device to the other of the first and second fans; and

maintaining a speed differential between the first and second fans in response to adjusting voltage supplied to one of the first and second fans so that one of the fans, being in an upstream position relative to the stream of air, is speed adjusted to a speed level higher than the other of the fans.