Patent Document

CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of co-pending U.S. patent application Ser. No. 13/231,739, filed Sep. 13, 2011, which is a continuation of U.S. patent application Ser. No. 12/372,660, filed Feb. 17, 2009, issued as U.S. Pat. No. 8,016,023, which is a continuation of U.S. patent application Ser. No. 11/395,900, filed Mar. 30, 2006, issued as U.S. Pat. No. 7,490,656, and which is a continuation of U.S. patent application Ser. No. 09/607,871, filed Jun. 30, 2000, issued U.S. Pat. No. 7,086,452. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to electronic devices and more particularly to the dissipation of heat generated by a microprocessor. 
     BACKGROUND 
     In operation, microprocessors and other electronic devices generate heat. Excess heat can damage a device if it is not dissipated. Therefore, generally, microprocessors and other heat-generating electronic devices utilize heat dissipating structures to dissipate excess heat. 
       FIG. 1  illustrates computer system  10  of the prior art. Microprocessor  40  or other heat-generating electronic devices generally are affixed to a printed circuit board (“PCB”)  20  that is coupled to spreader plate  30 . In the case of microprocessor  40 , a heat exchange system is usually affixed to the PCB through bolts or screws with an established gap or bond line thickness between a cooling plate or heat sink and microprocessor  40 . Heat pipe  55  is coupled to heat exchanger  50  which allows air to pass through air inlet  70  and exit air outlet  80 . Fan  60  generally continuously operates to cause air to pass through air inlet  70  and out air outlet  80  in order to cool computer system  10 . One disadvantage to a conventional computer system such as that shown in  FIG. 1  is due to the size of heat exchanger  50  and the limited capability of the heat pipe  55  to move heat to small air cooled heat exchanger  50  to cool a heat-generating source such as the microprocessor  40  that is shown in  FIG. 1 . What is needed is a configuration of a computer system whereby the heat-generating source is cooled at an enhanced rate. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. In the drawings, 
         FIG. 1  is a schematic angled view of a computer system of the prior art; 
         FIG. 2  illustrates a top angled view of a computer system in accordance with one embodiment of the invention; 
         FIG. 3  illustrates the path of fluid flow when an external source of fluid is used; 
         FIG. 4  illustrates a bi-directional tube coupled to an external chilled source in accordance with one embodiment of the invention; 
         FIG. 5  illustrates a bi-directional tube coupled to an external chilled source in accordance with one embodiment of the invention; 
         FIG. 6  illustrates a cross-sectional view of the first heat transfer plate in accordance with one embodiment of the invention; 
         FIG. 7  illustrates a top view of the first heat transfer plate in accordance with one embodiment of the invention; 
         FIG. 8  illustrates a top view of the second heat transfer plate in accordance with one embodiment of the invention; 
         FIG. 9  illustrates a cross-sectional view of the second heat transfer plate in accordance with one embodiment of the invention; 
         FIG. 10  illustrates a flow diagram in which fluid flows through a first and a second part of computing device in accordance with one embodiment of the invention one embodiment of the invention; and 
         FIG. 11  illustrates a flow diagram in which chilled fluid is supplied to the computing device. 
     
    
    
     DETAILED DESCRIPTION 
     The invention relates to a cooling system that improves the cooling capacity of a computer system and thereby improves the computing performance of the computer system. The computer system may include a notebook computer or other suitable portable computer systems. The computer system comprises a tube that is coupled to a first heat transfer plate and to a heat-generating element. The tube contains a fluid that removes heat from a heat source transferring it to a heat transfer plate. A second heat transfer plate is also used to transfer the waste heat from the cooling liquid to the ambient cooling air. In addition to cooling the computer system, techniques of the invention are also able to reduce noise about in the range of 35 to 45 decibels compared to conventional systems that use fans. An apparatus incorporating such a cooling system is described. 
       FIG. 2  illustrates an angled top side view of computer system  100  in accordance with one embodiment of the invention. In  FIG. 2 , microprocessor  130  is mounted on a printed circuit board (“PCB”) (not shown). Tube  115  provides cooling fluid to heat transfer plate  125  (also referred to herein as the first heat transfer plate). The fluid in tube  115  includes any fluid that may be used for cooling. For instance, water may be used. Water is the preferred fluid to use because water is easily replaceable when a portion of the water has dissipated and water causes less scaling in the heat transfer plate  125 . Additionally, if the water is accidentally released from computer system  100 , there are no environmental regulations that are triggered for the clean up of water as opposed to other fluids that may be regulated. Other fluids that may be used in tube  115  include various oils, fluorinert which is commercially available from 3M located in St. Paul, Minn., FC75, Coolanol 25, Coolanol 45, and liquid refrigerants. 
     Tube  115 , may comprise rubber, plastic such as polyvinyl chloride, aluminum, copper, stainless steel or other suitable material. Preferably, tube  115  in second part  120  of computing device  100  is comprised of metal such as stainless steel, aluminum, copper or any other suitable metal. Tube  115  located in first part  110  and second part  120  of computing device  100  may be made of the same or different material. In one embodiment, computer device  100  is a notebook or portable computer and first part  110  houses the motherboard, power supply and the like (not shown) as is well known in the art and second part  120  houses a liquid crystal display (not shown) or the like. Tube  115  has a diameter in the range of about 2 mm to 15 mm and a length that ranges from 500 mm to 5000 mm depending on the heat removal requirement. Tube  115  is secured to first part  110  and second part  120  of computer system  100 . There are a variety of ways that tube  115  may be secured to computer system  100 . Mechanical means may be used such as welding or soldering the tube to various heat spreaders and heat transfer plate, a stand off and clamps, or clips that surround tube  115  and attach to the base of computer system  110 . 
     There are also numerous ways in which tube  115  may be arranged relative to heat transfer plate  125  in first part  110  and heat transfer plate  210  (also referred to herein as the second heat transfer plate) in second part  120  of computing system  100  to remove heat generated by computer system  100  in the range of 10 watts to 50 watts.  FIG. 2  illustrates one such arrangement. Tube  115  is coupled to fluid container  140  which contains the fluid that is pumped by pump  150  at a rate of about 1 milliliter per second (“ml/sec”) to 10 ml/sec through tube  115 . Fluid container  140  generally has a volume that ranges from about 10 cubic centimeters (“cm 3 ”) to 25 cm 3 . The fluid contained within tube  115  may range from 25 ml to 250 ml. The thermal cooling capability is directly proportional to the mass flow rate of the cooling medium removing heat from the heat generation source to a heat rejection point such as a heat transfer plate. As a result, the amount of fluid pumped through tube  115  may increase or decrease the amount of cooling that occurs to microprocessor  130 . One skilled in the art, therefore, may adjust the mass flow rate by modifying the design parameters such as the length or the diameter of tube  115  in order to increase or decrease the rate of cooling. 
     Temperature sensor  180  is coupled to fluid container  140 , pump  150 , and to power management system  132 . Temperature sensor  180  is able to sense the temperature of microprocessor  130  when microprocessor  130  reaches a threshold level such as in the range of 70 to 100 Celsius that requires the cooling system to be activated in order to cool computer system  100 . The cooling system is activated when temperature sensor  180  sends a signal to power management system  132  indicating that a threshold temperature has been reached by microprocessor  130 . Power management system  132  controls operating conditions of the cooling system for computing device  100  such as the cooling fluid pumping rate. Power management system  132  may include memory or be coupled to a memory device. Memory may include read only memory (“ROM”), random access memory (“RAM”), magnetic disk storage media, optical storage media, flash memory devices, and/or other machine-readable media. Using program instructions stored within power management system  132  or in any other suitable location such as the chip set (not shown) of computer system  100 , power management system  132  controls the cooling system by then sending a signal to pump  150  to start pumping fluid from fluid container  140 . Once the temperature of microprocessor  130  is below the threshold temperature, power management system  132  sends another signal to pump  150  to stop pumping fluid from fluid container  150 . 
     Fluid sensor  190  is also coupled to fluid container  140  and to power management system  132 . Fluid sensor  190  is configured in such a manner to detect when the fluid contained in fluid container  140  reaches a level that requires fluid to be added to fluid container  140 . If the fluid in fluid container  140  is low, fluid sensor  190  sends a signal to power management system  132 . This indicates to power management system  132  that pump  150  should stop pumping. Power management system  132  may also send a signal to the graphic user interface of computer system  100  that the fluid is low in fluid container  140 . 
     Tube  115  is also coupled to coupling disconnect  170  which allows a user to detach tube  115  and couple tube  115  to an externally supplied chilled fluid or a fluid that is capable of reducing heat generated from microprocessor  130 . This externally supplied fluid is stored and pumped by the external cooling loop inside container  200 . Coupling disconnect  170  may be used to either augment the existing cooling system or disable a portion of the closed loop system formed by tube  115 .  FIG. 3  illustrates one such path of the fluid when the coupling disconnect  170  is used in conjunction with externally supplied fluid stored in container  200 . 
     Thereafter, tube  115  is connected to heat transfer plate  125  such as a plate-fin type liquid heat transfer plate that is located near microprocessor  130  in the first part  110  of computer system  100 . Plate-fin type liquid heat transfer plates utilize plates or fins that serve as heat-transfer surfaces and a frame to support the plates or fins. Heat-transfer plates generally comprise copper, aluminum, or stainless steel, but titanium, nickel, monel, Incoloy 825, Hastelloy C, phosphor bronze and cupronickel may also be used. Heat transfer plates or fins induce turbulence in the fluids and assure more efficient heat transfer and complete flow distribution. The cooling fluid passes through tube  115  and into one side of the heat transfer plate  125 . As the cooler fluid passes through heat transfer plate  125  and through a plurality of heat transfer fins  360  shown in  FIGS. 6 and 7 , heat is exchanged from the metal surfaces of the heat transfer plate to the cooling fluid. 
     After the heat is exchanged through heat transfer plate  125  which results in cooling microprocessor  130 , the fluid in tube  115  travels through the remainder of first part  110  and enters second part  120  of computing device  100 . The fluid follows the path of tube  115  in a vertical direction relative to first part  110  of computing device  100 . In the top portion of second part  120 , the fluid travels in a generally horizontal direction and then in a downward direction of second part  120  of computing device  100 . The fluid then exits second part  120  and enters coupling disconnect  170  and passes back into fluid container  140 . The cycle then repeats until microprocessor  130  is properly cooled to a temperature that is generally designated by the manufacturer of the computer system such as in the range of 70 to 100 Celsius. Alternatively, the fluid may be pumped in the reverse direction of the path described above. 
     In yet another embodiment of the invention, a different path of the fluid flow is shown in  FIG. 3 . Coupling disconnect  170  is connected to an externally chilled fluid source such as container  200 . The externally chilled fluid provides another route for the fluid to flow through computing device  100 . The fluid passes through fluid container  140  and travels beneath or around microprocessor  130  and through heat transfer plate  125 . The fluid exits tube  115  returning the fluid to container  200  through tube  198 .  FIGS. 4-5  illustrate cross-sectional views of bi-directional tube  198  shown in  FIG. 3  that allows cooling fluid to be transported to computing device  100  through a portion of tube  198  connected to container  200  and the fluid that has completed its path through the cooling system is returned to container  200  through another portion of bi-directional tube  198 . For example,  FIG. 4  illustrates a cross-sectional view of bi-directional tube  198  in which cooling fluid travels toward computing device through inner tube  117  and the fluid is returned to container  200  for chilling through tube  118 . Alternatively,  FIG. 5  illustrates dual tubes  119  in tandem. One tube is for allowing chilled fluid to be transported to the computing device  100  and the other tube allows the fluid to be returned to container  200 . In another embodiment, some other container (not shown) may be used to store the fluid that has been used to cool computing device  100 . 
     In yet another embodiment, the fluid does not bypass heat transfer plate  210 . Instead, after the fluid travels beneath or around microprocessor  130 , the fluid exits the first part  110  and enters the second part  120  of computing system  100 . The fluid then travels through heat transfer plate  210  of second part  120  of computing device  100 . Thereafter, the fluid exits tube  115  and enters container  200  or some other container (not shown). 
     In another embodiment, the fluid may flow in the reverse path. For example, the fluid may be pumped from container  200  to coupling disconnect  170 . From coupling disconnect  170 , the fluid enters tube  115  and begins to travel through second part  120  of computing device  100  following the path defined by tube  115 . The fluid exits second part  120  of computing device  100  and enters first part  110  of computing device  100 . The fluid travels beneath or near microprocessor  130  and then enters fluid container  140 . The fluid exits fluid container  140  and then enters container  200 . This external cooling system may be located in a variety of places such as a docking station, an alternating current battery charger brick, or some other suitable location. 
       FIGS. 6-8  show enlarged views of the first and second heat transfer plates ( 125 ,  210 ).  FIG. 6  illustrates a cross-sectional view of the heat transfer system for first heat transfer plate  125 . Solder balls  310  are connected to integrated circuit package  320  which is further coupled to integrated circuit  330 . Thermal bond line  340  acts as a conductive adhesive between integrated circuit  330  and first heat transfer plate  125 . Thermal bond line  340  may include materials such as grease, epoxy, elastomeric material, graphite, or any other suitable material. First heat transfer plate  125  is connected to a plurality of heat sink pin fins  360 . 
       FIG. 7  illustrates a top view of first heat transfer plate  125 . The heat generated from integrated circuit  330  is transferred through thermal bond line  340  to first heat transfer plate  125  and heat sink pin fins  360 . Fluid from tube  115  enters inlet  410  and passes over first heat transfer plate  125  and into heat sink pin fins  360 . The fluid has a turbulent flow through heat sink pin fins  360  which causes the fluid to have longer contact with first heat transfer plate  125  and heat sink pin fins  360 . The heat is transferred from first heat transfer plate  125  and heat sink pin fins  360  to the fluid which exits first heat transfer plate  125  through outlet  420  and reenters tube  115 . 
       FIG. 8  illustrates a top view of second heat transfer plate  210  that is located in second part  120  of computing device  100 . Second heat transfer plate  210  has a large surface area that allows heat to be transferred to ambient air through conduction and convection. Tube  115  is arranged to have a plurality of passes in second part  120  of computing device  100  in order to take advantage of the large surface area of second heat transfer plate  210 . Fluid enters inlet  410  and follows the path of tube  115  and exits outlet  420 . In addition, air passes through air inlet  440 , travels across heat transfer plate  115  and exits air outlet  450  which also serves to cool computer system  100 . 
       FIG. 9  illustrates a cross-sectional view of second heat transfer plate  210 . A plurality of fins  430  are located perpendicular to display  444 . Fins  430  are air cooled as described above which provides greater heat transfer from tube  115  and the ambient air. 
       FIG. 10  illustrates a flow diagram of one embodiment of the invention. At block  500 , a first heat transfer plate is located near or underneath an electronic component in a first part of a computing device. At block  510 , at least one tube is coupled to a first heat transfer plate and a second heat transfer plate. The tube that is connected to the first transfer plate may be made of one material such as plastic whereas the tube connected to the second heat transfer plate may comprise another material such as metal. Alternatively, the tube may be made of the same material. At block  520 , fluid is circulated through the tube coupled to the first heat transfer plate and to the second heat transfer plate. At block  530 , heat is removed from the electronic component. 
       FIG. 11  illustrates a flow diagram in which chilled fluid is supplied to the computing device. At block  600 , a tube having chilled fluid is coupled to a coupling disconnect. At block  610 , the tube is located near an electronic component such as microprocessor. At block  620 , the tube is coupled to a first heat transfer plate and a second heat transfer plate. At block  630 , fluid is circulated through the tube coupled to the first and second heat transfer plates. At block  640 , heat is removed from the electronic component. 
     In the preceding detailed description, the invention is described with reference to specific embodiments thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the invention as set forth in the claims. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.

Technology Category: g