Abstract:
A method and apparatus for cooling heat-producing equipment, the method comprising the steps of directing heat from the heat producing equipment to a cooling loop and, circulating liquid through said cooling loop from a liquid reservoir to a radiator structure. In a first exemplary embodiment, the apparatus comprises a liquid reservoir, a pump, a radiator and a plurality of interface members. In a second exemplary embodiment, the apparatus comprises a liquid reservoir, a pump, a radiator and an air-to-liquid heat exchanger.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to a method and apparatus for removing heat from electronic equipment, and in particular, a method and apparatus for removing heat from a plurality of circuit cards disposed in an electronics cabinet.  
         BACKGROUND OF THE INVENTION  
         [0002]    Cooling systems for electronics are well known. Devices such as heat pipes, thermal fins, and pumped cooling systems have been used to provide cooling for electronic equipment such as processors, circuit cards and integrated circuits. For example, U.S. Pat. No. 5,343,940 describes a flexible heat transfer device for cooling electronic elements disposed on circuit boards. Similarly, U.S. Pat. Nos. 5,884,693 and 6,076,595 to Austin et al. teach a heat pipe enclosure which is used to cool electronics disposed within the enclosure. Finally, U.S. Pat. No. 5,890,371 discloses a hybrid air conditioning system for cooling heat-producing equipment such as electronics.  
           [0003]    U.S. Pat. No. 6,208,510 describes a cooling system for cooling an integrated test cell  10 . The test cell  10  includes a plurality of electronic circuit boards  18  disposed in card cages  14 ,  16 . In order to keep these circuit boards  18  cool, a liquid-liquid heat exchanger  46  is disposed above the circuit boards. The heat exchanger  46  takes heated air produced by the circuit boards  18  and heats liquid disposed therein. This heated liquid is then passed to a thermal controller  52  (basically a housing filled with chilled liquid) through liquid line  50 . The heated liquid is cooled at the thermal controller  52  and is passed back to the heat exchanger  46  through liquid line  48 . In this way, liquid is continually circulated from the heat exchanger  46  to the thermal controller  52  and back again. Cooled air which passes out of the heat exchanger  46  reaches a circulation unit  58  (e.g., fan) which forces the cooled air to be re-circulated back to a bottom side of the circuit boards  18 .  
           [0004]    However, all of the above-described patented systems fail to adequately cool electronics with speed and efficiency. In particular, the cooling system described in the &#39;510 patent fails to adequately cool the circuit cards  18  due at least in part to the inefficient placement of-the circulation unit  58  and the heat exchanger  46 . Further, the fact that the heat exchanger  46  comprises an air-liquid to liquid-liquid unit, significantly reduces the cooling properties of the cooling system.  
           [0005]    Thus, there is presently a need for a cooling system which quickly and efficiently cools electronic equipment.  
         SUMMARY OF THE INVENTION  
         [0006]    The present invention is method and apparatus for cooling heat-producing equipment, the method comprising the steps of directing heat from the heat producing equipment to a cooling loop and, circulating liquid through said cooling loop from a liquid reservoir to a radiator structure.  
           [0007]    The above and other advantages and features of the present invention will be better understood from the following detailed description of the exemplary embodiments of the invention which is provided in connection with the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    [0008]FIG. 1 is a block diagram showing an electronics cabinet and cooling system according to a first exemplary embodiment of the present invention.  
         [0009]    [0009]FIG. 2 is a block diagram showing an electronics cabinet and cooling system according to a second exemplary embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0010]    Referring to FIG. 1, there is shown a cooling system  100  according to a first exemplary embodiment of the present invention. The cooling system  100  includes a housing  110  containing heat-producing equipment  115 . In the first exemplary embodiment, the heat-producing equipment  115  comprises circuit boards  116  with heat-producing circuits disposed thereon, however, the heat-producing equipment  115  may comprise many different kinds of equipment, as will be understood by those skilled in the art. The cooling system  100  also may include a solar shield  111  which at least partially surrounds the housing  110 , and which protects the housing from the heating rays of the sun.  
         [0011]    The cooling system  100  also includes a reservoir  120  of liquid, a pump  125 , a radiator structure  130 , interface members  135 , and tubing  140  coupling the reservoir to the interface members. The reservoir  120 , pump  125 , radiator structure  130  and tubing  140  combine to form a ‘cooling loop’  160 . In the first exemplary embodiment, the interface members  135  also form part of the cooling loop  160 . The tubing  140  may be made of any suitable material, but is preferably made of plastic or Copper (Cu). Moreover, the liquid disposed in the reservoir  120  may be any type of liquid, but is preferably chilled water or anti-freeze.  
         [0012]    The interface members  135  preferably comprise laminates of heat conducting material (e.g., Copper) with liquid flow channels disposed therein. The liquid flow channels are preferably coupled to the tubing  140 , so that liquid from the reservoir  120  may be pumped therethrough. The liquid present in the flow channels of the interface members  135  is heated by the circuit boards  116 , and is transferred through the cooling loop  160  by the pump  125 . In this manner, the interface members  135  conduct heat generated by the circuit boards  116  away from the circuit boards and into the cooling loop  160 . The heated liquid is then moved to the radiator structure  130  where the heat is dissipated into the ambient air by convection. The interface members  135  may be customized and sized to fit the circuits, circuit boards, or other heat-producing equipment  115  to which they are attached. The interface members  135  may be attached to the respective heat-producing equipment  115  via a strap or tie, mechanical fasteners, and/or pressure sensitive adhesive (PSA).  
         [0013]    The radiator structure  130  preferably comprises a laminate of heat conducting material (e.g., Copper). The radiator structure  130  may also include a plurality of fins  131  as shown in FIG. 1, for further assisting in conducting heat away from the housing  110 . The fins  131  increase the surface area of the radiator structure  130 , thereby permitting more heat to be dissipated. The radiator structure  130  is preferably disposed between the solar shield  111  and an exterior wall of the housing  110 . The radiator structure  130  may be attached to the exterior wall of the housing  110  or suspended from the exterior wall by fastening means (e.g., mechanical fasteners, PSA, etc.). Connecting the radiator structure in this manner allows the wall of the housing  110  to become a heat transfer surface under natural or forced convection conditions.  
         [0014]    The system  100  pumps liquid from the reservoir  120  via tubing  140  to the interface members  135 . Liquid passes through the interface members  135 , thus absorbing the heat generated by the circuit boards  116 . The fluid continues to be pumped to the radiator structure 130 , where the heat is released to the outside environment by convection.  
         [0015]    Referring to FIG. 2, there is shown a cooling system  200  according to a second exemplary embodiment of the present invention. The cooling system  200  includes a housing  210  containing heat-producing equipment  215 . In the second exemplary embodiment, the heat-producing equipment  215  comprises circuit boards  216 , with heat-producing circuits disposed thereon, however, the heat-producing equipment  215  may comprise many different kinds of equipment, as will be understood by those skilled in the art.  
         [0016]    The cooling system  200  also includes a reservoir  220  of liquid, a pump  225 , a radiator structure 230 , an air-to-liquid heat exchanger  235 , a circulation unit  236 , and tubing  240  coupling the reservoir to the other portions. The reservoir  220 , pump  225 , radiator structure  230  and tubing  240  combine to form a ‘cooling loop’  260 . In the second exemplary embodiment, the air-to-liquid heat exchanger  235  also forms part of the cooling loop  260 . The tubing  240  may be made of any suitable material, but is preferably made of plastic or Copper (Cu). Moreover, the liquid disposed in the reservoir  220  may be any type of liquid, but is preferably chilled water or anti-freeze.  
         [0017]    The air-to-liquid heat exchanger  235  preferably comprises a mechanism for accepting heated air and transferring heat from such heated air to liquid through a heat exchanger core. Accordingly, the air-to-liquid heat exchanger  235  may comprise a heat pipe or other equivalent structure. The circulation unit  236  (e.g. fan) disposed adjacent to the air-to-liquid heat exchanger  235  serves to transmit heat from the heated air produced by the heat producing equipment  115  to the air-to-liquid heat exchanger.  
         [0018]    The radiator structure  230  preferably comprises a laminate of heat conducting material (e.g., Copper). The radiator structure  230  may also include a plurality of fins  231  as shown in FIG. 2, for further assisting in conducting heat away from the housing  210 . The radiator structure  230  is preferably disposed between the solar shield  211  and an exterior wall of the housing  210 . The radiator structure  230  may be attached to the exterior wall of the housing  210  or suspended from the exterior wall by fastening means (e.g., mechanical fasteners, PSA, etc.). Connecting the radiator structure in this manner allows the wall of the housing  210  to become a heat transfer surface under natural or forced convection conditions.  
         [0019]    The radiator structure  230 , along with air-to-liquid heat exchanger  235 , creates an air-to-liquid, liquid-to-air (AL/LA) heat transfer path which is superior to most conventional heat transfer systems. This AL/LA transfer path quickly and efficiently transfers heat away from the housing  210 . The AL/LA transfer path provides significant advantages over conventional heat transfer systems (e.g., the air-to-liquid, liquid-to-liquid (AL/LL) transfer path proposed in U.S. Pat. No. 6,208,510 discussed above), as it allows more flexibility in the packaging of the cooling system  200 . In particular, separating the air-to-liquid (AL) unit from the liquid-to-air (LA) unit, and connecting those units through a tubing loop, allows the separate units to be placed virtually anywhere within the cooling system  200 , thus greatly expanding the design possibilities for the cooling system (i.e., the design is not limited to particular placements of the air-to-liquid and liquid-to-air units).  
         [0020]    Moreover, the specific placement of the circulation unit  236  between the heat producing equipment  215  (e.g., circuit boards  216 ) and the air-to-liquid heat exchanger  235  permits the second exemplary embodiment to transfer heat away from the heat producing equipment with more speed and efficiency than in conventional designs. For example, in U.S. Pat. No. 6,208,510, the heat exchanger ( 46 ) is disposed between the circulation unit ( 56 ) and the circuit cards ( 18 ), thus substantially limiting airflow from the circuit cards to the heat exchanger. In other words, heated air from the circuit cards ( 18 ) must travel around the heat exchanger ( 46 ) in order for the circulation unit ( 56 ) to be effective. In the second exemplary embodiment, there is nothing to block the airflow from the circuit boards  216  to the heat exchanger  235 , and thus, heat can be transferred more quickly and efficiently.  
         [0021]    The system  200  pumps liquid from the reservoir  220  via tubing  240  to the air-to-liquid heat exchanger  235 . Liquid passes through the air-to-liquid heat exchanger  235 , thus absorbing the heat generated by the circuit boards  216 . The fluid continues to be pumped to the radiator structure  230 , where the heat is released to the outside environment by convection.  
         [0022]    Although the above discussion refers to interface members  135  which preferably comprise laminates of Copper, it will be noted by those skilled in the art that such interface members may be formed of laminates of plastic and/or other polymers.  
         [0023]    Although the invention has been described in terms of exemplary embodiments, it is not limited thereto. Rather, the appended claims should be construed broadly, to include other variants and embodiments of the invention which may be made by those skilled in the art without departing from the scope and range of equivalents of the invention