Pumps – Condition responsive control of pump drive motor – Plural pumps having separate drive motors – supply sources,...
Reexamination Certificate
1997-10-01
2001-06-19
Freay, Charles G. (Department: 3746)
Pumps
Condition responsive control of pump drive motor
Plural pumps having separate drive motors, supply sources,...
C417S042000, C417S045000, C165S080300, C236S0010EA
Reexamination Certificate
active
06247898
ABSTRACT:
RELATED APPLICATIONS
The subject matter of U.S. patent application Ser. No. 08/914,262 entitled “COMPUTER FAN SPEED CONTROL SYSTEM METHOD,” and having attorney Docket No. MNFRAME.035A is related to this application.
APPENDICES
Appendix A, which forms a part of this disclosure, is a list of commonly owned copending U.S. patent applications. Each one of the applications listed in Appendix A is hereby incorporated herein in its entirety by reference thereto.
COPYRIGHT RIGHTS
A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent files or records, but otherwise reserves all copyright rights whatsoever.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to computer equipment and, in particular, relates to a system and a method for sensing and controlling the speed of one or more cooling fans used to cool personal computers.
2. Description of the Related Art
As personal computers have become increasingly sophisticated, there has been an increased need for cooling devices which will remove ambient heat from the air surrounding the electronic components, of the personal computer. Specifically, as personal computers have become increasingly sophisticated, these computers are using increased numbers of electronic components each of which produce greater amounts of heat. This heat can result in damage to components within the chassis or casing of the personal computer or can also result in a decrease in the longevity of the electronic components.
Therefore, it is desirable to reduce the amount of ambient heat in and around the electronic components comprising the personal computer. Various devices are used to reduce or remove the heat. For example, heat sinks are often attached to heat generating electronic components, such as microprocessors, and fans are also used for forced air cooling of the electronic components. Specifically, fans are used to blow air over the heat generating electronic components and also to blow the accumulated hot air away from the atmosphere surrounding the components to thereby lower the air temperature and allow for more heat to be radiated out of the component.
Generally, it is desirable to operate the fans at the lowest speed possible that still provides adequate cooling. Slower speed of operation prolongs the longevity of the fan and also decreases the noise generated by the personal computer. In some applications, there can be as many fans/simultaneously operating to cool the computer. At high speed operation, the noise generated by these fans would be distracting to the computer user. Hence, there is a desire to use fans that operate at lower speeds and still provide adequate cooling.
Moreover, in many personal computers, a plurality of fans are used to cool the chassis section of the personal computer. Generally, the number of fans is selected to provide a desired amount of forced air cooling with some redundancy. The redundancy is provided so that if one or more of the fans fail, adequate cooling can still be provided by the remaining fans. This redundancy, however, increases the overall cost of the computer as more fans are installed than are actually needed for normal cooling operations. Further, it will be appreciated that when all of the fans are operating, the fans are generating an increased amount of noise.
Many personal computers are also equipped with dual or multi-speed DC fans that operate at different speeds depending upon the ambient conditions within the personal computer. This allows a controller to select the speed for the fans that provide the optimum cooling without using excessive power or causing excessive wear on the fans. Unfortunately, these multi-speed fans are more expensive and increase the overall cost of the personal computer. In the highly competitive market of personal computers, a small increase in the component cost can result in a significant effect on the overall profitability of the sale of the personal computer. Consequently, it is desirable to be able to use the least expensive components that are capable of performing the necessary functions.
Moreover, while multi-speed fans are currently available for use with personal computers, if one of these fans fail, the prior art personal computers are often unable to detect the failure and to take corrective action. While multi-speed fans can be used to provide varying cooling capacity within the personal computer chassis, these systems are not generally capable of accommodating a failure of one or more of the fans. Hence, the multi-speed fans are also generally selected so as to provide more cooling capacity than is actually required to account for the subsequent loss of one or more fans. This of course causes greater power drain on the power supply, results in noisier computers and also decreases the longevity of the fans themselves.
Hence, there is a need for an inexpensive cooling fan system which is capable of adequately cooling a personal computer. To this end, there is a need for a cooling fan system which can operate at different speeds to provide varying cooling capacity that is less expensive and simpler in construction than systems that have been previously available. There is also a need for an inexpensive cooling fan system for a computer that is capable of determining when one or more of the fans in the cooling fan system has failed and then of inducing other fans to increase their speed to account for the loss of the one or more fans.
SUMMARY IF THE INVENTION
The aforementioned needs are satisfied by the cooling system for a computer of the invention. In one aspect of the invention a cooling system for a computer is provided. The system comprises a plurality of fans adapted to provide forced air cooling of a computer wherein each of the plurality of fans operates at a speed that is related to the voltage that is applied to the fan, 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 the first position, the plurality of fans receives a first input voltage and operates at a normal speed and so that when the switch is in a second position the plurality of fans receives a second input voltage and operates at a higher speed 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
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the fans are operating at an undesired speed of operation and, upon ascertaining that at least one of the plurality of fans is operating at an undesired speed of operation, induces the switch to move to a second position so that at least one of the remaining fans in the plurality of fans operates at higher speed of operation. In one embodiment of this aspect of the invention, 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 a first voltage by a fixed voltage amount.
In another aspect of the invention, a cooling system for a computer is provided which comprises a plurality of fans adapted to provide forced-air cooling of a computer where each of the plurality of fans operates at a speed that is related to the voltage that is applied to the fans, a volt
Henderson Michael G.
Johnson Karl S.
Nguyen Ken
Freay Charles G.
Knobbe Martens Olson & Bear LLP
Micron Electronics Inc.
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