Abstract:
A computer system comprising a computer chassis supporting at least one electronic component, a rack chassis supporting the computer chassis, a heat sink disposed between said computer chassis and said rack chassis, and wherein said heat sink is thermally coupled to said computer chassis and to said rack chassis such that heat is conducted between said computer chassis, said heat sink, and said rack chassis.

Description:
BACKGROUND 
       [0001]    Computer systems include numerous electrical components that draw electrical current to perform their intended functions. For example, a computer&#39;s microprocessor or central processing unit (“CPU”) requires electrical current to perform many functions such as controlling the overall operations of the computer system and performing various numerical calculations. Generally, any electrical device through which electrical current flows produces heat. The amount of heat any one device generates generally is a function of the amount of current flowing through the device. 
         [0002]    Typically, an electrical device is designed to operate correctly within a predetermined temperature range. If the temperature exceeds the predetermined range (i.e., the device becomes too hot or too cold), the device may not function correctly, thereby potentially degrading the overall performance of the computer system. Thus, many computer systems include cooling systems to regulate the temperature of their electrical components. Air-cooled systems often utilize an array of fans to move air from the environment, through a computer enclosure, and back to the environment. As the air passes through the enclosure it comes in thermal contact with, and absorbs heat from, the heat-generating components within the enclosure. The heat transfer rate that can be achieved by an air-cooled system is a function of the volume of air that can be moved through the enclosure and the temperature of that air. 
         [0003]    Many computer systems and components, such as servers, routers, and storage arrays, are configured for mounting in rack enclosures that allow for efficient storage of multiple components. Many rack enclosures are essentially large cabinets into which a plurality of components are mounted. These racks are often designed for densely storing a multitude of components while allowing for easy access to the components for upgrading and maintenance. It is not unusual to find a number of racks co-located in a server farm, or other large grouping of components. 
         [0004]    Computer system designs, such as rack-mounted servers, that seek to increase computational power while reducing the size of computer equipment create many challenges with controlling the temperature within these ‘dense’ computer systems. Increasing the computational power of computer systems often results in the utilization of high power components that generate high levels of heat. Also, increasing the computational power of computer systems results in increasing the footprint of the heat-generating components while maintaining the same storage volume and air flow heat transfer capacity. Reducing the size of the computer system often involves packaging components in close proximity to each other, therefore restricting airflow through the systems. The combination of high power, high heat-generating components and compact design is pushing the limits of current air-cooled systems. 
       SUMMARY 
       [0005]    A computer system comprising a computer chassis supporting at least one electronic component, a rack chassis supporting the computer chassis, a heat sink disposed between said computer chassis and said rack chassis, and wherein said heat sink is thermally coupled to said computer chassis and to said rack chassis such that heat is conducted between said computer chassis, said heat sink, and said rack chassis. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    For a detailed description of exemplary embodiments of the invention, reference will now be made to the accompanying drawings in which: 
           [0007]      FIG. 1  shows an array of computer systems and rack constructed in accordance with embodiments of the invention; 
           [0008]      FIG. 2  shows a computer system and rack; 
           [0009]      FIG. 3  shows a computer system and rack constructed in accordance with embodiments of the invention; 
           [0010]      FIG. 4  shows a partial top view of the computer system and rack of  FIG. 3 ; 
           [0011]      FIG. 5  shows thermal couplings constructed in accordance with embodiments of the invention; 
           [0012]      FIG. 6  shows thermal couplings constructed in accordance with embodiments of the invention; 
           [0013]      FIG. 7  shows a side view of thermal couplings constructed in accordance with embodiments of the invention; 
           [0014]      FIG. 8  shows a side view of thermal couplings constructed in accordance with embodiments of the invention; 
           [0015]      FIG. 9  shows a side view of thermal couplings constructed in accordance with embodiments of the invention; and 
           [0016]      FIG. 10  shows a side view of thermal couplings constructed in accordance with embodiments of the invention. 
       
    
    
     NOTATION AND NOMENCLATURE 
       [0017]    Certain terms are used throughout the following description and claims to refer to particular system components. As one skilled in the art will appreciate, computer companies may refer to a component by different names. This document does not intend to distinguish between components that differ in name but not function. In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . .” Also, the term “couple” or “couples” is intended to mean either an indirect or direct connection. Thus, if a first device couples to a second device, that connection may be through a direct connection or through an indirect connection via other devices and connections., 
       DETAILED DESCRIPTION 
       [0018]    The following discussion is directed to various embodiments of the invention. Although one or more of these embodiments may be preferred, the embodiments disclosed should not be interpreted, or otherwise used, as limiting the scope of the disclosure, including the claims. In addition, one skilled in the art will understand that the following description has broad application, and the discussion of any embodiment is meant only to be exemplary of that embodiment, and not intended to intimate that the scope of the disclosure, including the claims, is limited to that embodiment. 
         [0019]    Referring to  FIG. 1 , a computer system  10  comprises rack chassis or frame  20  having top end  22 , bottom end  24 , front end  26 , and back end  28 . Rack chassis  20  supports a plurality of computer components  30 . In an exemplary air flow configuration, air  32  from the environment is drawn into each computer component  30 . The air removes heat from electronic components within computer component and exhausts air  34  back to the environment. 
         [0020]    Computer component  30  may be any number of devices, including a computer or server. Referring to  FIG. 2 , a server system  50  comprises rack  52  supporting computer system  54 . Computer system  54  comprises chassis  56  having front end  58 , back end  62 , and sides  60 ,  64 . Inlet  66  is disposed through front end  58  and outlet  70  is disposed through back end  62 . Computer system  54  comprises numerous electronic components including hard drives  74 , power supplies  76 , memory modules  78 , and processors  80 . By way of example, computer system  54  of  FIG. 2  further comprises air movers  82 , but air movers are not necessary to all embodiments in accordance with the invention. Chassis  56  is slidingly engaged with rack  52  via sliding means such as rails disposed adjacent sides  60 ,  64 . 
         [0021]    Referring now to  FIG. 3 , another view of server system  50  is shown. Rail assemblies  86  mounted to the inside of rack  52  allow computer system  54  to be removed and replaced by a sliding action; rail assemblies  86  support computer system  54  adjacent sides  60 ,  64  when computer  54  is in position in rack  52 . Computer chassis  56  further comprises thermal coupling  90  mounted to sides  60 ,  64  just below rail assemblies  86 . A counterpart thermal coupling  92  is mounted to the inside of rack  52  such that couplings  90 ,  92  are in thermal communication when computer chassis  56  slides into place. In alternative embodiments of the invention, couplings  90 ,  92  may be mounted in other locations such that they engage each other for thermal contact when computer  54  is installed. Fluid conduits  94  are supported by rack chassis  52  and extend through coupling  92  such that fluid conduits thermally communicate with coupling  92 . Fluid conduits  94  may carry water, for example, or refrigerant, or any other liquid coolant. 
         [0022]    Coupling faces  96 ,  98  of couplings  90 ,  92 , respectively, are shown as flat surfaces in  FIG. 3 . Coupling faces  96 ,  98  create a flat surface on flat surface thermal conduction relationship between couplings  90 ,  92 . The thermal conduction relationship between couplings  90 ,  92  is not limited to flat surfaces, and other exemplary embodiments of thermal conduction relationships will be described herein. 
         [0023]    Couplings  90 ,  92  are constructed such that they operate as heat sinks. For example, couplings  90 ,  92  comprise aluminum, copper, alloys thereof or any other lightweight material having significant thermal conductivity. They are also constructed with appropriate dimensions for appreciable heat conduction. Thus, the heat sinks of couplings  90 ,  92  conduct significant amounts of heat, as opposed to other components of computer  54  which conduct only limited or negligible quantities of heat. Other components of computer  54 , such as internal metallic components, chassis  56 , or rail assemblies  86 , may include conductive metals, but do not function as heat sinks because they are not capable of conducting significant amounts of heat necessary for computer system cooling. When mated, couplings  90 ,  92  combine to form a larger heat sink than the individual heat sinks of couplings  90 ,  92 . 
         [0024]    Still referring to  FIG. 3 , heat that is collected in thermal coupling  92  is carried away by water flowing through fluid conduits  94 . Fluid conduits  94  communicate with a fluid delivery system in rack  52  (not shown). Referring briefly to  FIG. 1 , cooled water from source  42  is brought into rack  22  through inlet  40  at the bottom of rack  22  and delivered to the various thermal couplings in rack  22 . Heat is transferred from the couplings to the water, and the heated water is exhausted from rack  22  through outlet  44  to a cooling system  46 . 
         [0025]    Referring to  FIG. 4 , computer chassis  56  and rack chassis  52  are thermally connected by couplings  100 ,  102 . Unlike the flat surface to flat surface relationship of thermal couplings  90 ,  92 , couplings  100 ,  102  comprise an alternative interlocking, overlapping, or mating relationship. The interlocking, mating relationship of couplings  100 ,  102  is further shown in  FIGS. 5-7 . As shown in  FIG. 5 , coupling  100  comprises top end  103 , sides  111 ,  115 , and a plurality of ridges or teeth  105  on face  104 . Each of ridges  105  comprises reduced or curved portion  108 . Coupling  102  comprises top end  109 , sides  113 ,  117 , and a plurality of ridges or teeth  107  on face  106 . Each of ridges  107  comprises reduced or curved portion  110 . Couplings  100 ,  102  are adapted to be heat sinks, as previously described with respect to couplings  90 ,  92 . In  FIG. 7 , the interlocking relationship of couplings  100 ,  102  is shown in a side view. Ridges  105  mate with ridges  107  to form an even larger heat sink. 
         [0026]    An interlocking relationship between the thermally conductive surfaces of the couplings provides stability to the thermal coupling, an increased surface area for thermal conduction, and self-alignment of the couplings as they slidingly engage each other. As seen in  FIG. 5 , faces  104 ,  106  of couplings  100 ,  102 , respectively, comprise a series of ridges  105 ,  107 . The ridges create a saw-tooth shape as seen in the profile side view of  FIG. 7 . To bring the couplings  100 ,  102  into the mating relationship shown in  FIG. 7 , server coupling  100  must slide into rack coupling  102  as computer system  54  slides into rail assemblies  86  of rack  52 . In alternative embodiments of the invention, rails assemblies  86  are not included as couplings  100 ,  102  also act as the supporting rail assemblies 
         [0027]    Referring back to  FIG. 4 , computer system  54  and chassis  56  support hard drive  74 , power supply  76 , and processor  80 . Heat conductors  124  couple each of hard drive  74 , power supply  76 , and processor  80  to back surface  112  of coupling  100 . Heat conductors  124  extend from the back of coupling  100  and into chassis  56  such that heat conductors  124  are thermally coupled to the several computer components and thermal coupling  100 . Heat conductors  124  comprise heat pipes, for example, that are capable of moving heat from one location to another, most notably, between conductive surfaces having different temperatures. 
         [0028]    Still with reference to  FIG. 4 , rack chassis  52  comprises heat exchangers  120  mounted within the chassis enclosure. Contact surfaces  126  of heat exchangers  120  are disposed adjacent and in contact with back surface  114  of coupling  102 . A robust contact between surfaces  126  and surface  114  ensures proper thermal conduction between heat exchangers  120  and coupling  102 , thus coupling  102  may be mounted or otherwise securely attached to heat exchangers  120 . Heat exchangers  120  comprise fluid conduits  122  for carrying water or other cooled liquid. The arrangement causes heat exchangers  120  to be thermally coupled to coupling  102  such that heat is removed from coupling  102  by conduction to heat exchanger  120 . Fluid conduits  122  communicate with liquid delivery and exhaust lines, such as delivery line  40  and exhaust line  44  of rack  20  in  FIG. 1 , so that cool water is brought continuously through heat exchangers  120  and exhausted therefrom as needed. Other examples of heat exchangers may be developed by persons of ordinary skill in the art with reference to the teachings of this disclosure. 
         [0029]    To facilitate engagement of couplings  100 ,  102  as computer  54  slides into place, lead portions  111 ,  113 , respectively, comprise reduced or curved portions  108 ,  110  of ridges  105 ,  107 . As lead portion  111  advances toward lead portion  113  in the Z-direction, reduced portion  108  allows greater tolerance for misalignment in the Y-direction with reduced portion  110 . As reduced portion  108  engages reduced portion  110  misaligned couplings  100 ,  102  are forced into alignment as coupling  100  advances further relative to coupling  102  and full ridge portions  105 ,  107 , respectively, are engaged. During the advancement of coupling  100 , the tolerances between ridges  105 ,  107  are reduced and thermal contact is maximized. Therefore, couplings  100 ,  102  comprise a self-alignment feature such that the couplings are disposed as shown in  FIG. 4  (top view) and  FIG. 7  (side view) when fully engaged (the gap shown in  FIG. 7  is for clarity purposes only, and does not represent an actual gap between couplings  100 ,  102  as they are in contact for thermal conduction). 
         [0030]    In contrast,  FIG. 6  shows exemplary embodiments of couplings  130 ,  132  that do not have reduced ridge portions  108 ,  110 . Lead portions  141 ,  143  require greater alignment in the Y-direction for proper sliding engagement of couplings  130 ,  132  such that lead portion  141  does not interfere with lead portion  143  as coupling  130  advances toward coupling  132  in the Z-direction. 
         [0031]    In addition to the self-alignment feature of the couplings, the interlocking relationship of the couplings provides increased stability of the contact between the couplings as opposed to contact between flat surfaces, for example, as flat surfaces tend to move more easily relative to each other. Further, movement in the X-direction of  FIG. 7 , due to tolerances in rack chassis  52 , computer chassis  56 , and rail assembly  86 , would cause flat surfaces to lose contact. As shown in  FIG. 8 , movement in the X-direction between couplings  100 ,  102  may cause couplings to move apart relative to each other, but remain in significant thermal contact at surfaces  119 . As coupling  102  moves slightly away from coupling  100 , gravity or other forces in computer system  10  will force couplings  100 ,  102  into contact at surfaces  119 . 
         [0032]    Further exemplary embodiments of the couplings are shown in  FIGS. 9 and 10 . Referring to  FIG. 9 , couplings  200 ,  202  comprise faces  204 ,  206 , respectively, having ridges  205 ,  207  forming mating curved or sinusoidal shapes Referring to  FIG. 10 , couplings  300 ,  302  comprise faces  304 ,  306 , respectively, having ridges  305 ,  307  forming mating square or block shapes The couplings of  FIGS. 9 and 10  may also comprise the self-alignment features previously described. The coupling faces of  FIGS. 4-10  comprise profile shapes that increase the thermal contact surface area over a flat surface. Further, the mating relationship between two coupling faces in accordance with the exemplary embodiments described herein will maintain significant thermal contact despite an imperfect fit. Other examples of mating shapes for the coupling faces may be developed by persons of ordinary skill in the art with reference to the teachings of this disclosure. 
         [0033]    The components of the thermal conduction cooling system described herein are considered substantially independent of air moving or cooling devices, such as air movers  82 . The exemplary embodiments of the invention described herein do not depend on air flow, or convection, to move heat from the heat-generating components of a computer system. Thus, the thermal conduction cooling system described herein may be used to supplement an air moving or cooling system, or supplant such a system such that no fluid is moved through the computer system for cooling purposes. The thermal conduction cooling system described herein does not require air movers, potentially reducing the complexity, space, and noise needed to cool a computer system, and also focusing the heat transfer on a smaller volume of hardware as opposed to a larger volume of air. Further, heat conductors  124  thermally couple components internal to computer chassis  56  to coupling  100  external of chassis  56 . Thus, it is not necessary for the cooled liquid to exit rack chassis  52 , or for any fluid, including air, to enter computer chassis  56 . Communicating a liquid out of rack-chassis  52  and into computer chassis  56  is an awkward and cumbersome process, and increases the risk of exposing sensitive computer components to hazardous liquids. 
         [0034]    The above discussion is meant to be illustrative of the principles and various embodiments of the present invention. Numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. For example, embodiments of the invention may or may not include air movers as the thermal conduction of the invention is independent of air movement. Further, the interface between the thermal couplings comprises various shapes, for example. It is intended that the following claims be interpreted to embrace all such variations and modifications.