Computer fan speed control system

• US 6,247,898 B1
• Filed: 10/01/1997
• Issued: 06/19/2001
• Est. Priority Date: 05/13/1997
• Status: Expired due to Term

• Current Assignee: Round Rock Research LLC
• Original Assignee: Micro Electronics Incorporated
• Inventors: Nguyen, Ken, Johnson, Karl S., Henderson, Michael G.
• Primary Examiner(s): FREAY, CHARLES GRANT
• Application Number:
  US08/940,301
• Time in Patent Office: 1,357 Days
• Field of Search: 417/2, 417/3, 417/42, 417/45, 417/425, 165/80.3, 361/278, 361/690, 361/695, 622/592, 236/1.E
• US Class Current: 417/3
• CPC Class Codes: F04D 25/166 using fans
• CPC Class Codes: F04D 27/004 by varying driving speed
• CPC Class Codes: G06F 1/20 Cooling means
• CPC Class Codes: G06F 1/206 comprising thermal management
• CPC Class Codes: G06F 1/26 Power supply means, e.g. regulation thereof for memories G11C
• CPC Class Codes: G06F 11/0748 in a remote unit communicating with a single-box computer node experiencing an error/fault remote testing G06F11/2294
• CPC Class Codes: G06F 11/0772 Means for error signaling, e.g. using interrupts, exception flags, dedicated error registers
• CPC Class Codes: G06F 11/0793 Remedial or corrective actions recovery from an exception in an instruction pipeline G06F9/3861; by retry G06F11/1402; for recovering from a failure of a protocol instance or entity H04L69/40
• CPC Class Codes: G06F 11/3058 Monitoring arrangements for monitoring environmental properties or parameters of the computing system or of the computing system component, e.g. monitoring of power, currents, temperature, humidity, position, vibrations thermal management in cooling arrangements of a computing system G06F1/206
• CPC Class Codes: G06F 11/3072 where the reporting involves data filtering, e.g. pattern matching, time or event triggered, adaptive or policy-based reporting
• CPC Class Codes: G06F 11/3093 Configuration details thereof, e.g. installation, enabling, spatial arrangement of the probes
• CPC Class Codes: G06F 11/328 Computer systems status display G06F11/327 takes precedence
• CPC Class Codes: G06F 11/3466 Performance evaluation by tracing or monitoring
• CPC Class Codes: G06F 13/4027 using bus bridges G06F13/4022 takes precedence
• CPC Class Codes: G06F 21/305 by remotely controlling device operation
• CPC Class Codes: G06F 2201/86 Event-based monitoring
• CPC Class Codes: G06F 3/0601 Interfaces specially adapted for storage systems
• CPC Class Codes: G06F 3/0673 Single storage device
• CPC Class Codes: G06F 9/4411 Configuring for operating with peripheral devices; Loading of device drivers
• CPC Class Codes: H04L 12/12 Arrangements for remote connection or disconnection of substations or of equipment thereof
• CPC Class Codes: H05K 7/20209 : Thermal management, e.g. fan control
• CPC Class Codes: Y02B 30/70 : Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating
• CPC Class Codes: Y02D 30/50 : in wire-line communication networks, e.g. low power modes or reduced link rate

Abstract

A cooling system for cooling components of a computer is provided. The cooling system includes a DC fan which operates at a speed which is substantially proportional to the voltage that is applied to the fan. A zener diode voltage divider is connected in series between a voltage source and a first input of the fan. The second input of the fan is connected to a reference voltage source. A switch is also connected in series between the voltage source and the first voltage input of the fan so as to be connected in parallel with the zener diode voltage divider. When the switch is in a first position, the voltage produced by the voltage source is applied directly to the fan allowing the fan to operate at a first speed. When the switch is in a second position, the voltage from the voltage source is applied to the first input of the fan through the zener diode such that the first input of the fan receives a second voltage that is less than the first voltage thereby causing the fan to operate at a second speed. The zener diode voltage divider is substantially current independent such that the voltage drop across the zener diode is substantially independent of the current that is drawn by the fan.

Claims

1. A cooling system for a computer comprising:

a plurality of fans adapted to provide forced air cooling of a computer wherein each of the plurality of fans operate at a speed that is related to the voltage that is applied to the fans;

a voltage source that provides a first voltage;

at least one voltage divider connected to the voltage source and the plurality of fans so as to be interposed between the plurality of fans and the voltage source;

at least one switch connected to the voltage source and to the plurality of fans so as to be interposed between the plurality of fans and the voltage source, so that when the switch is in a first position, the plurality of fans receive a first input voltage and operate at a normal speed and so that when the switch is in a second position the plurality of fans receive a second input voltage and operate at a higher speed of operation which is more than the normal speed of operation;

a speed monitoring system which provides an indication of the speed of operation of the plurality of fans; and

a controller that receives signals from the speed monitoring system and ascertains if at least one of the plurality of fans are operating at an undesired speed of operation and, upon ascertaining that at least one of the plurality of fans are operating at an undesired speed of operation, induces the switch to move to the second position so that at least one of the remaining fans in the plurality of fans operate at the higher speed of operation.

2. The system of claim 1, wherein the plurality of fans are two input DC fans that operate at a speed of operation that is proportional to the voltage that is applied to the fans.

3. The system of claim 1, wherein the at least one voltage divider is comprised of a zener diode voltage divider that is interposed between the voltage source and the input for the plurality of fans such that when the switch is in the second position, the voltage from the voltage source is provided to the plurality of fans via the zener diode voltage divider such that the input voltage received by the plurality of fans is reduced from the first voltage by a fixed voltage amount.

4. The system of claim 1, wherein the at least one switch is a transistor having a gate that receives an input signal from the controller on the gate, wherein the transistor is connected in parallel with the voltage divider such that when the transistor is turned on, the first voltage produced by the voltage supply is applied directly to the plurality of fans.

5. The system of claim 4, wherein the at least one switch is comprised of a P-channel MOSFET.

6. The system of claim 1, wherein the speed monitoring system is comprised of:

a plurality of tachometers that are integrally connected to each of the fans and provide a digital output signal indicative of the speed of operation of the fan; and

a sampling system that sequentially samples each of the plurality of tachometer outputs.

7. The system of claim 6, wherein the sampling system includes a multiplexer that receives an input signal from the controller inducing the multiplexer to sequentially sample each of the tachometer outputs.

8. The system of claim 1, wherein the controller, upon determining that at least one of the fans is not operating at a desired speed of operation, creates a record indicating that the at least one fan is not operating at the desired speed and induces the switch to close to thereby induce the remaining fans to increase their speed of operation.

9. The system of claim 8, wherein the controller upon subsequently determining that the at least one fan operating at an undesired speed is operating at a desired speed, induces the switch into the first position thereby reducing the speed of operation of the fans to the normal speed.

10. The system of claim 1, wherein the voltage produced by the voltage source comprises 12 volts DC and approximately 12 volts DC is applied to the plurality of fans to induce the plurality of fans to operate at the higher speed and wherein the voltage divider reduces the voltage applied to the fans to approximately 9 volts DC to induce the fans to operate at the normal speed of operation.

11. A cooling system for a computer comprising:

a plurality of fans adapted to provide forced air cooling of a computer wherein each of the plurality of fans operate at a speed that is related to the voltage that is applied to the fans;

a voltage source that provides a first voltage;

at least one zener diode voltage divider connected to the voltage source and the plurality of fans so as to be interposed between the plurality of fans and the voltage source;

at least one switch connected to the voltage source and to the plurality of fans so as to be interposed between the plurality of fans and the voltage source, so that when the switch is in a first position, the plurality of fans receive a first input voltage and operate at a normal speed and so that when the switch is in a second position the plurality of fans receive a second input voltage and operate at a higher speed of operation which is more than the normal speed of operation;

a speed monitoring system which provides an indication of the speed of operation of the plurality of fans; and

a controller that receives signals from the speed monitoring system and ascertains if at least one of the plurality of fans are operating at an undesired speed of operation and, upon ascertaining that at least one of the plurality of fans are operating at an undesired speed of operation, induces the switch to move to the second position so that at least one of the remaining fans in the plurality of fans operate at the higher speed of operation.

12. The system of claim 11, wherein the plurality of fans are two input DC fans that operate at a speed of operation that is proportional to the voltage that is applied to the fans.

13. The system of claim 11, wherein the at least one zener diode voltage divider that is interposed between the voltage source and the input for the plurality of fans such that when the switch is in the second position, the voltage from the voltage source is provided to the plurality of fans via the zener diode voltage divider such that the input voltage received by the plurality of fans is reduced from the first voltage by a fixed voltage amount.

14. The system of claim 11, wherein the at least one switch is a transistor having a gate that receives an input signal from the controller on the gate, wherein the transistor is connected in parallel with the voltage divider such that when the transistor is turned on, the first voltage produced by the voltage supply is applied directly to the plurality of fans.

15. The system of claim 14, wherein the at least one switch is comprised of a P-channel MOSFET.

16. The system of claim 11, wherein the speed monitoring system is comprised of:

a plurality of tachometers that are integrally connected to each of the fans and provide a digital output signal indicative of the speed of operation of the fan; and

a sampling system that sequentially samples each of the plurality of tachometer outputs.

17. The system of claim 16, wherein the sampling system includes a multiplexer that receives an input signal from the controller inducing the multiplexer to sequentially sample each of the tachometer outputs.

18. The system of claim 11, wherein the controller, upon determining that at least one of the fans is not operating at a desired speed of operation, creates a record indicating that the at least one fan is not operating at the desired speed and induces the switch to close to thereby induce the remaining fans to increase their speed of operation.

19. The system of claim 18, wherein the controller upon subsequently determining that the at least one fan operating at an undesired speed is operating at a desired speed, induces the switch into the first position thereby reducing the speed of operation of the fans to the normal speed.

20. The system of claim 11, wherein the voltage produced by the voltage source comprises 12 volts DC and approximately 12 volts DC is applied to the plurality of fans to induce the plurality of fans to operate at the higher speed and wherein the voltage divider reduces the voltage applied to the fans to approximately 9 volts DC to induce the fans to operate at the normal speed of operation.

21. A cooling system for a computer comprising:

a plurality of fans adapted to provide forced air cooling of a computer wherein each of the plurality of fans operate at a speed that is related to the voltage that is applied to the fans;

a voltage source that provides a first voltage;

at least one zener diode voltage divider connected to the voltage source and the plurality of fans so as to be interposed between the plurality of fans and the voltage source;

at least one switch connected to the voltage source and to the plurality of fans so as to be interposed between the plurality of fans and the voltage source, so that when the switch is in a first position, the plurality of fans receive a first input voltage and operate at a normal speed and so that when the switch is in a second position the plurality of fans receive a second input voltage and operate at a higher speed of operation which is more than the normal speed of operation;

a speed monitoring system which provides an indication of the speed of operation of the plurality of fans; and

a controller that receives signals from the speed monitoring system and ascertains if at least one of the plurality of fans are operating at an undesired speed of operation and, upon ascertaining that at least one of the plurality of fans are operating at an undesired speed of operation, induces the switch to move to the second position so that at least one of the remaining fans in the plurality of fans operate at the higher speed of operation wherein the controller, upon determining that at least one of the fans is not operating at a desired speed of operation, creates a record indicating that the at least one fan is not operating at the desired speed and wherein the controller upon subsequently determining that the at least one fan operating at an undesired speed is operating at a desired speed, induces the switch into the first position thereby reducing the speed of operation of the at least one of the remaining fans to the normal speed.

22. The system of claim 21, wherein the plurality of fans are two input DC fans that operate at a speed of operation that is proportional to the voltage that is applied to the fans.

23. The system of claim 21, wherein the at least one zener diode voltage divider that is interposed between the voltage source and the input for the plurality of fans such that when the switch is in the second position, the voltage from the voltage source is provided to the plurality of fans via the zener diode voltage divider such that the input voltage received by the plurality of fans is reduced from the first voltage by a fixed voltage amount.

24. The system of claim 21, wherein the at least one switch is a transistor having a gate that receives an input signal from the controller on the gate, wherein the transistor is connected in parallel with the voltage divider such that when the transistor is turned on, the first voltage produced by the voltage supply is applied directly to the plurality of fans.

25. The system of claim 24, wherein the at least one switch is comprised of a P-channel MOSFET.

26. The system of claim 21, wherein the speed monitoring system is comprised of:

a plurality of tachometers that are integrally connected to each of the fans and provide a digital output signal indicative of the speed of operation of the fan, and

a sampling system that sequentially samples each of the plurality of tachometer outputs.

27. The system of claim 26, wherein the sampling system includes a multiplexer that receives an input signal from the controller inducing the multiplexer to sequentially sample each of the tachometer outputs.