Abstract:
A pump or DC fan used to cool an electronic system is monitored for speed. When the pump or fan encounters an unexpected increase in impedance, such as an obstruction or a bearing anomaly, the controller temporarily increases the power to the pump or fan to overcome the impedance, and optionally notifies the user of the pump or fan problem. Also, when the pump or fan impedance returns to a normal range, the controller returns the power to the pump or fan to normal levels. In some embodiments, the controller may supply more power to the pump or fan than specified by the manufacturer to temporarily over come the increased impedance or pending failure of the pump or fan. This increased power allows the fan or pump to operate at a speed necessary for cooling an electronic system during a temporary increase in impedance, or during a slow degradation of the efficiency of the fan or pump.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates generally to the field of cooling technologies and more specifically to the field of cooling technologies within a device enclosure including cooling fans or pumps.  
       BACKGROUND OF THE INVENTION  
       [0002]     As technology advances, more and more heat-generating electronic devices are packed into smaller and smaller enclosures. With most electronic devices, there is a critical temperature above, which the device or devices will no longer operate correctly. Currently there are a wide variety of methods used to cool electronic device enclosures including fans for air-cooling devices and liquid cooling techniques where a cooling liquid is pumped through the enclosure. As with most moving mechanical devices, these fans and pumps are subject to wear, causing their operating characteristics to change. Also, a fan or pump may be temporarily blocked by an obstruction, reducing the efficiency of the fan or pump. When these events occur, the cooling system may no longer operate sufficiently to keep the electronic devices being cooled within their operating temperature range. At this point the device may fail, causing expensive downtime for repairs to the fan or pump, and possibly expensive repairs to the electronic devices themselves.  
         [0003]     Many DC fans are capable of operation for short times above their maximum rated voltage. While exceeding the maximum rated voltage may shorten the lifetime of a fan, it may be desirable to sacrifice fan lifetime in exchange for the prevention of unscheduled down time. In most electronic systems, fan cost is a small fraction of the cost of the rest of the system. Typically fan cost is also small relative to the cost of unscheduled downtime for the system. Thus, in some situations, it is desirable to have the ability to apply higher voltages to a fan or pump to temporarily maintain necessary system cooling capability, while allowing a user to schedule time for repairing or replacing the fan or pump (if necessary) at a time convenient to the user. This would allow the system to avoid sudden unexpected system failures, and allows the system user more flexibility in scheduling repairs to the cooling system.  
       SUMMARY OF THE INVENTION  
       [0004]     A pump or DC fan used to cool an electronic system is monitored for speed. When the pump or fan encounters an unexpected increase in impedance, such as an obstruction or a bearing anomaly, the controller temporarily increases the power to the pump or fan to overcome the impedance, and optionally notifies the user of the pump or fan problem. Also, when the pump or fan impedance returns to a normal range, the controller returns the power to the pump or fan to normal levels. In some embodiments, the controller may supply more power to the pump or fan than specified by the manufacturer to temporarily over come the increased impedance or pending failure of the pump or fan. This increased power allows the fan or pump to operate at a speed necessary for cooling an electronic system during a temporary increase in impedance, or during a slow degradation of the efficiency of the fan or pump.  
         [0005]     Other aspects and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]      FIG. 1  is a graph of fan speed of two different fans, one of which has an increase in impedance.  
         [0007]      FIG. 2  is a graph showing the reaction of the controller to a fan, which has an increase in impedance according to an example embodiment of the present invention.  
         [0008]      FIG. 3  is a view of a DC fan and controller according to an example embodiment of the present invention.  
         [0009]      FIG. 4  is a view of a pump and controller according to an example embodiment of the present invention.  
         [0010]      FIG. 5  is a flowchart of an example embodiment of the control of fan speed according to the present invention.  
         [0011]      FIG. 6  is a flowchart of an example embodiment of the control of pump speed according to the present invention.  
         [0012]      FIG. 7  is a flowchart of an example embodiment of the control of liquid flow speed according to the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0013]      FIG. 1  is a graph of fan speed of two different fans, one of which has an increase in impedance. In this graph, the vertical axis  100  represents fan speed in revolutions per minute (rpm) increasing from bottom to top, and the horizontal axis  102  represents time increasing from left to right. The long dashed line  104  represents fan speed data for a normally operating fan. This normal fan operates near a fan speed of S 1   110 . The short dashed line  106  represents fan speed data for a fan that has an increase in impedance at time T 1   108 . This increase in impedance manifests itself in a reduction in fan speed from speed S 1   110  to speed S 2   112  at time T 1   108 . In this example, the increase in impedance is permanent. The fan speed never recovers back to the normal speed S 1   110  but remains indefinitely at a slower speed S 2   112 . This type of failure may signal a bearing problem with the fan that will require the fan to be replaced. However, the problem is that the slower fan speed S 2   112  may not be sufficient to cool the electronic system it is associated with. Thus, the system may fail unexpectedly due to this inadequate cooling. By increasing the power to the fan, the system may be adequately cooled until it is convenient for the user to shut down the system and replace the fan instead of being faced with an unexpected system failure. Even if the increased power shortens the lifespan of the fan, it is to the user&#39;s benefit since the fan needed to be replaced anyway. Any extra time provided the user to gracefully shut down the system is invaluable.  
         [0014]      FIG. 2  is a graph showing the reaction of the controller to a fan, which has an increase in impedance according to an example embodiment of the present invention. This graph is similar to that of the failing fan from  FIG. 1 , and includes the voltage applied to the failing fan along with the resulting corrected fan speed. Like  FIG. 1  this graph has a left vertical axis  100  representing fan speed in rpm increasing from bottom to top, and a horizontal axis representing time increasing from left to right. In addition, this graph has a right vertical axis  214  representing fan voltage in volts (V) increasing from bottom to top. There are three lines plotted on this graph. First the fan speed of the failing fan as shown in  FIG. 1  is represented by the short dashed line  106 . The voltage supplied by the controller to the failing fan is represented by the solid line  200  which is measured by the right vertical axis  214 . Finally the long dashed line  202  represents the fan speed of the failing fan as corrected by the present invention. This long dashed line  202  is measured by the fan speed left vertical axis  100 . As in  FIG. 1  the fan speed of the failing fan decreases from a first speed S 1   206  to a second speed S 2   208  at a time T 1   204  representing an increase in impedance occurring at time T 1   204 . However, in this example embodiment of the present invention, the fan speed data is sent to a controller that responds to the decrease in fan speed by increasing the voltage supplied to the fan. Thus, at time T 1   204  the voltage supplied to the fan represented by the solid line  200  increases from a first voltage V 1   210  to a second voltage V 2   212 . In some embodiments of the present invention, this second voltage V 2   212  may be higher than the maximum rated voltage of the fan, thus shortening the lifespan of the fan, but allowing the user time to schedule maintenance of the system when convenient. Those of skill in the art will recognize that this technique also applies to cases where the control of pump speed is critical, and that similar techniques may be used to monitor pump speed and vary pump power in response to increases in pump impedance.  
         [0015]      FIG. 3  is a view of a DC fan and controller according to an example embodiment of the present invention. In this example embodiment of the present invention a DC cooling fan  300  including a motor  302 , fan blades  304  and power input connection  308  is configured to allow the capture of fan speed data. In some configurations the fan motor  302  itself supplies fan speed data  310  to a controller  314 . In other configurations a fan speed sensor  306 , such as an optical counter is used to send fan speed data  312  to the controller  314 . When an increased impedance manifests itself as a slower fan speed the controller  314  determines a voltage necessary to supply to the fan to return the fan speed to a normal speed and sends a control signal  316  to the power supply  318  that in turn, sends increased power through power conductors  320  to the fan  300 . Those of skill in the art will recognize that a wide variety of algorithms may be used within the controller  314  to actively control the fan speed to a normal speed within the scope of the present invention. In some example embodiments of the present invention the controller  314  may also send a warning  322  to a user when the controller  314  increases fan voltage above a certain level.  
         [0016]      FIG. 4  is a view of a pump and controller according to an example embodiment of the present invention.  FIG. 4  is similar to  FIG. 3  except that the example embodiment of the present invention is used to control the speed of a pump. In this example embodiment of the present invention a rotary pump  400  is used to drive a liquid through a tube  402 . The speed of the pump  400  or the liquid within the tube  402  may be measured to determine the cooling efficiency of the system. In some example embodiments of the present invention pump speed data  410  may be sent from the pump  400  to a controller  412 . In other example embodiments of the present invention a flow detector  406  may send flow speed data  408  to the controller  412 . Still other example embodiments of the present invention may use both pump speed data  410  and flow speed data  408  to determine the proper power to supply to the pump  400 . The controller  412  determines a proper voltage or power level to supply to the pump  400  and sends a control signal  414  to the pump power supply  416 . When an increased impedance manifests itself as a slower pump speed or flow speed the controller  412  determines a voltage or power necessary to supply to the pump to return the pump speed or flow speed to a normal speed and sends a control signal  414  to the power supply  416  that in turn, sends increased power through power conductors  420  to the pump  400 . Those of skill in the art will recognize that a wide variety of algorithms may be used within the controller  412  to actively control the pump speed to a normal speed within the scope of the present invention. In some example embodiments of the present invention the controller  412  may send a warning  422  to a user when the controller  412  increases pump power above a certain level. Those of skill in the art will recognize that this pump may be a compressor pump used in a cooling system where the compressor pump compresses a refrigerant. Pump speed may be monitored to detect any variations in impedance.  
         [0017]      FIG. 5  is a flowchart of an example embodiment of the control of fan speed according to the present invention. In a step  500 , the speed of a fan is monitored. In a decision step  502  if the fan speed is at a normal speed, control is passed back to step  500  to continue monitoring. If the fan speed is not at a normal speed, control is passed to a decision step  504 . In a decision step  504 , if the fan speed is below the normal speed, control is passed to step  506 . If the fan speed is above the normal speed, control is passed to step  510 . In step  510  the power supplied to the fan is decreased and control is passed back to step  500  to continue monitoring. In step  506  the power supplied to the fan is increased and in an optional step  508  a warning is sent to a user. Then control is passed pack to step  500  to continue monitoring.  
         [0018]      FIG. 6  is a flowchart of an example embodiment of the control of pump speed according to the present invention. In a step  600 , the speed of a pump is monitored. In a decision step  602  if the pump speed is at a normal speed, control is passed back to step  600  to continue monitoring. If the pump speed is not at a normal speed, control is passed to a decision step  604 . In a decision step  604 , if the pump speed is below the normal speed, control is passed to step  606 . If the pump speed is above the normal speed, control is passed to step  610 . In step  610  the power supplied to the pump is decreased and control is passed back to step  600  to continue monitoring. In step  606  the power supplied to the pump is increased and in an optional step  608  a warning is sent to a user. Then control is passed pack to step  600  to continue monitoring.  
         [0019]      FIG. 7  is a flowchart of an example embodiment of the control of liquid flow speed according to the present invention. In a step  700 , the flow speed of a liquid is monitored. In a decision step  702  if the flow speed is at a normal speed, control is passed back to step  700  to continue monitoring. If the flow speed is not at a normal speed, control is passed to a decision step  704 . In a decision step  704 , if the flow speed is below the normal speed, control is passed to step  706 . If the flow speed is above the normal speed, control is passed to step  710 . In step  710  the power supplied to the pump is decreased and control is passed back to step  700  to continue monitoring. In step  706  the power supplied to the pump is increased and in an optional step  708  a warning is sent to a user. Then control is passed pack to step  700  to continue monitoring.  
         [0020]     The foregoing description of the present invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and other modifications and variations may be possible in light of the above teachings. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and various modifications as are suited to the particular use contemplated. It is intended that the appended claims be construed to include other alternative embodiments of the invention except insofar as limited by the prior art.