Abstract:
An electronics rack comprising a frame, a heat sink coupled to the frame, and a cage adapted to support an electronic component. The cage is movable between first and second positions toward and away from the heat sink. The rack further includes an eccentric cam operatively positioned between the frame and the cage and being rotatable to move the cage between the first and second positions. In one embodiment, the cage comprises a cooling brick movable toward and away from the heat sink when the cage moves between the first and second positions. The cooling brick can include a first heat pipe extending generally in a first direction and a second heat pipe extending generally in a second direction transverse to the first direction. For example, the first heat pipe can be embedded in a top plate and the second heat pipe can be embedded in a top cold rail.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This patent application claims priority to U.S. patent application No. 62/299,318, filed on Feb. 24, 2016, the entire contents of which are incorporated herein by reference. 
     
    
     FEDERALLY SPONSORED RESEARCH 
       [0002]    This invention was made with government support under purchase order number 7016038 awarded by Bechtel Marine Propulsion Corporation (BMPC)-Knolls Atomic Power Laboratory (KAPL). The government has certain rights in the invention. 
     
    
     BACKGROUND 
       [0003]    In many electronic systems, the efficient cooling of electronic components and other heat sources has become a significant problem. With the advent of large-scale integrated circuit (IC) modules containing many thousands of circuit elements, it has become possible to pack large numbers of electronic components together within a very small volume. These integrated circuit modules generate significant amounts of heat during the course of their normal operation. Since most solid state devices are sensitive to excessive temperatures, a solution to the problem of the generation of heat by large scale IC&#39;s in close proximity to one another has become of increasing concern in the industry. 
         [0004]    Current heat transfer systems have proven to be inadequate for removing the high levels of heat generated by heat sources at a low enough thermal resistance and at a sufficiently fast rate. Thus, there has developed a need to more efficiently remove heat from electronics systems. 
       SUMMARY 
       [0005]    The present invention provides an electronics rack comprising a frame, a heat sink coupled to the frame, and a cage adapted to support an electronic component. The cage is movable between a first position away from the heat sink and a second position toward the heat sink. The rack further includes an eccentric cam operatively positioned between the frame and the cage (e.g., below a portion of the cage) and being rotatable to move the cage between the first and second positions. 
         [0006]    In one embodiment, the cage comprises a cooling brick (e.g., comprising a heat pipe) movable toward and away from the heat sink when the cage moves between the first and second positions. The cooling brick can include a first heat pipe extending generally in a first direction and a second heat pipe extending generally in a second direction transverse (e.g., perpendicular) to the first direction. Preferably, the first and second heat pipes lie is different planes. For example, the cooling brick can comprise a top plate and a top cold rail, wherein the first heat pipe is embedded in the top plate and the second heat pipe is embedded in the top cold rail. 
         [0007]    Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a perspective view of an electronics rack embodying the present invention. 
           [0009]      FIG. 2  is an enlarged perspective view of the electronics rack of  FIG. 1  showing a lower cage with a portion of the rack removed for clarity. 
           [0010]      FIG. 3  is the view of  FIG. 2  with the lower cage slid to an open position. 
           [0011]      FIG. 4  is a partial side view of the electronics rack of  FIG. 2 . 
           [0012]      FIG. 5  is an enlarged view of the circled portion of  FIG. 4  and showing an upper contact bar spaced from a rear heat sink. 
           [0013]      FIG. 6  is the view of  FIG. 5  with the upper contact bar moved into contact with the rear heat sink. 
           [0014]      FIG. 7  is a rear perspective view of the lower cage from the electronics rack of  FIGS. 1 and 2 . 
           [0015]      FIG. 8  is a bottom view of the lower cage of  FIG. 7 . 
           [0016]      FIG. 9  is an enlarged front view of the cage of  FIG. 2  showing a PCB assembly positioned in the cage. 
           [0017]      FIG. 10  is a partially exploded view of the PCB assembly from  FIG. 9 . 
           [0018]      FIG. 11  is a section view of the assembled PCB assembly take at line  11 - 11  in  FIG. 9 . 
           [0019]      FIG. 12  is an enlarged front perspective view of an upper portion of the electronics rack of  FIG. 1  showing an upper cage with portions of the electronics rack removed for clarity. 
           [0020]      FIG. 13  is an exploded perspective view of a power supply assembly. 
           [0021]      FIG. 14  is a perspective view of the upper cage. 
           [0022]      FIG. 15  is a section view of an upper plate from the upper cage taken along line  15 - 15  in  FIG. 14 . 
           [0023]      FIG. 16  is a bottom perspective view of an upper heat sink. 
           [0024]      FIG. 17  is a perspective view of a front face of the upper cage and eccentric cams. 
           [0025]      FIG. 18  is a section view of the power supply cage and eccentric cams in a lowered position and taken along line  18 - 18  in  FIG. 17 . 
           [0026]      FIG. 19  is the section view of  FIG. 18  with the eccentric cams in a raised position. 
       
    
    
     DETAILED DESCRIPTION 
       [0027]    Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the accompanying drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. The terms “mounted,” “connected” and “coupled” are used broadly and encompass both direct and indirect mounting, connecting and coupling. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings, and can include electrical connections or couplings, whether direct or indirect. 
         [0028]      FIG. 1  illustrates an electronics cabinet  30  positioned on a base  32 . The cabinet  30  includes a rack  34  and a door  36  hinged to the rack  34 . The cabinet  30  is designed to receive multiple printed circuit board (PCB) assemblies  38  and multiple power supply assemblies  40 , as described below in more detail. 
         [0029]    The rack  34  includes a frame  42 , a substantially horizontally oriented upper heat sink  44  positioned above and supported by the frame  42 , a substantially vertically oriented rear heat sink  46  positioned behind the frame  42 , and a plurality of lower and upper cages  48 , 50  slidable into and out of the frame  42 . In the illustrated embodiment, there are a total of four cages—three lower cages  48  and one upper cage  50 . The three lower cages  48  in  FIG. 1  are each adapted to support a plurality of the PCB assemblies  38  (only one PCB assembly is shown in each lower cage in  FIG. 1 ), and the upper cage  50  in  FIG. 1  is adapted to support a plurality of power supply assemblies  40 , as described below in more detail. 
         [0030]    Referring to  FIGS. 2-8 , each of the lower cages  48  includes a front face  52 , an upper thermal collector  54 , a lower thermal collector  56 , and left and right side walls  58  to form a generally box-like arrangement. This box-like arrangement is designed to slide into and out of the frame  42  on drawer slides  60  between a closed position ( FIG. 2 ) and an open position ( FIG. 3 ). Handles  62  on the front face  52  facilitate opening the lower cages  48 . 
         [0031]    Referring to  FIGS. 4-8 , the upper thermal collector  54  includes an upper plate  64 , upper heat pipes  66  partially embedded in the upper plate  64 , and an upper contact bar  68  attached to distal ends of the upper heat pipes  66 . As best shown in  FIGS. 7-8 , each of the upper heat pipes  66  is essentially identical to the others, and each includes a non-linear portion  70  between the upper plate  64  and the upper contact bar  68 . In the illustrated embodiment, the non-linear portion  70  is curved to facilitate flexing of the upper heat pipe  66  in order to change the overall length of the upper thermal collector  54 . 
         [0032]    Similarly, the lower thermal collector  56  includes a lower plate  72 , lower heat pipes  74  partially embedded in the lower plate  72 , and a lower contact bar  76  attached to the distal ends of the lower heat pipes  74 . As with the upper heat pipes  66 , each of the lower heat pipes  74  is essentially identical to each other, and each includes a non-linear portion  78  that is curved to facilitate flexing of the lower heat pipes  74  in order to allow a change in length of the lower thermal collector  56 . 
         [0033]    As used herein, a “heat pipe” refers to a closed system of heat transfer in which a small amount of liquid within a sealed and evacuated enclosure is cycled through an evaporation and condensation cycle, as is known in the art. Heat entering the enclosure at one location on the casing or “pipe” evaporates liquid at that location, producing vapor which moves to a cooler location on the casing where it is condensed. The movement of the vapor is motivated by a small vapor pressure differential between the evaporator and the condenser locations. The heat transfer is accomplished when the heat of vaporization, which produces the vapor, is essentially moved with the vapor to the condenser location where it is given up as the heat of condensation. In order for the heat transfer to continue, the condensed liquid must be returned from the condenser to the evaporator where it will again be vaporized. Although this return can be accomplished by something as simple as gravity, capillary wicks have generally been used to permit heat pipes to be independent of the effects of gravity. Such a wick extends from a location near the condenser, where the liquid originates, to a location at the evaporator where it is needed for evaporation. 
         [0034]    Referring to  FIGS. 9-11 , a series of cold rails  80  is positioned on a lower surface of the upper plate  64  and on an upper surface of the lower plate  72  to thereby define a series of elongated slots adapted to receive the plurality of PCB assemblies  38 . A resilient wedge lock  82  ( FIG. 11 ) is positioned in each slot to secure each of the PCB assemblies  38  in the corresponding slots, as described below in more detail. 
         [0035]    Each of the PCB assemblies  38  includes a printed circuit board  84 , a primary cold plate  86  and a secondary cold plate  88 . As shown in  FIGS. 9-11 , the primary and secondary cold plates  86 , 88  sandwich the printed circuit board  84  to facilitate heat transfer from the printed circuit board  84  to the cold plates  86 , 88 . Preferably, the cold plates  86 , 88  are made from aluminum to enhance the rate of heat transfer. As shown in  FIG. 11 , each of the PCB assemblies  38  is inserted into a corresponding slot in a lower cage  48  and is held in place by being sandwiched between the corresponding wedge lock  82  and the corresponding cold rail  80 . 
         [0036]    Each of the lower cages further includes an upper adjuster and a lower adjuster adapted to adjust the length of the upper and lower thermal collectors  54 , 56 , respectively. Referring to  FIGS. 7-8 , each of the upper and lower adjusters includes five threaded rods  94  connected between the front face  52  and the corresponding contact bar  68 , 76 . The proximate end  96  of each of the threaded rods  94  is keyed for rotation relative to the front face  52 . In addition, each proximate end  96  extends slightly from the front face  52  and includes means to facilitate rotation of the threaded rod  94 , as shown in  FIG. 4 . In the illustrated embodiment, the proximate end  96  of each threaded rod  94  is slotted to facilitate insertion of a flathead screwdriver and rotation of the threaded rod  94 . The distal end  98  of each of the threaded rods  94  is threaded into a corresponding threaded hole in the corresponding contact bar  68 , 76 . By rotating the threaded rods  94 , the positon of the corresponding contact bar  68 , 76  relative to the rear heat sink  46  (and relative to the front face  52 ) will be adjusted. In the illustrated embodiment, this adjustment can be up to five millimeters of displacement. 
         [0037]    Referring to  FIGS. 1-3 , the rear heat sink  46  includes a rear plate  100  positioned at a rear of the rack  34  in a position where it can be contacted by the contact bars  68 , 76  upon closing of the lower cages  48  (with appropriate adjustment of the upper and lower adjusters  90 , 92 ). The rear heat sink  46  further includes rear heat pipes  102  embedded in the rear plate  100  in order to distribute heat received from the contact bars  68 , 76  throughout a greater volume of the rear plate  100 . The rear heat sink  46  further includes rear fins  104  extending from a rear surface of the rear plate  100  to facilitate passive dissipation of heat to the surrounding air. 
         [0038]    In operation, each of the lower cages  48  can be slid out of the rack  34  to facilitate insertion and removal of PCB assemblies  38 . After all of the PCB assemblies  38  are properly installed in the corresponding slots, the lower cage  48  can be slid back into the rack  34 . However, because of the variability and tolerances of the cabinet  30 , it is possible that the upper and lower contact bars  68 , 76  do not properly engage the rear heat sink  46 . Without solid engagement between the contact bars  68 , 76  and the rear heat sink  46 , heat dissipation from the thermal collectors  54 , 56  to the rear heat sink  46  is substantially compromised. In order to facilitate solid contact between the contact bars  68 ,  76  and the rear heat sink  46 , the threaded rods  94  can be rotated to move the contact bars  68 , 76  from a spaced position ( FIG. 5 ) to a contacting position ( FIG. 6 ) relative to the rear heat sink  46 . 
         [0039]    Referring to  FIG. 12 , the upper cage  50  is designed to receive a plurality of power supply assemblies  40  (only one power supply assembly is shown in  FIG. 12 ). The construction and arrangement of the upper cage  50  is slightly different from the lower cages  48  in that the upper cage  50  promotes heat transfer upward, while the lower cages  48  promote heat transfer rearward. The illustrated upper cage  50  includes a front face  108 , a top plate  110 , a bottom plate  112 , and left and right side walls  114  connecting the top and bottom plates  110 , 112  to form a generally box-like arrangement. As with the lower cages  48 , the upper cage  50  includes a series of top and bottom cold rails  116 , 118  (secured to the top and bottom plates  110 , 112 , respectively) that define slots for receiving the power supply assemblies  40 . However, in this arrangement, the top cold rails  116  are different from the bottom cold rails  118 . Specifically, as shown in  FIGS. 12, 14, and 15 , the top cold rails  116  each include two embedded heat pipes  120  for distributing heat in each of the top cold rails  116 . In addition, the top plate  110  is different from the bottom plate  112  in that the top plate  110  includes a plurality of embedded heat pipes  122  positioned transverse to the orientation of the top cold rails  116  (see  FIGS. 14-15 ). These transverse heat pipes  122  transfer and distribute heat throughout the top plate  110 . For convenience, the combined assembly of the top plate  110  and the top cold rails  116  is referred to as a “cooling brick,” it being understood that a cooling brick would not necessarily need to have those components. 
         [0040]    As with the lower cages  48 , the upper cage  50  includes wedge locks  124  ( FIGS. 18-19 ) positioned in the slots to facilitate securing the power supply assemblies  40  in the slots. 
         [0041]    Similar to the PCB assemblies  38 , the power supply assemblies  40  include a power supply board  126 , a primary cold plate  128 , and a secondary cold plate  130  (see  FIG. 13 ). The power supply board  126  is sandwiched between the primary and secondary cold plates  128 , 130  to facilitate the transfer of heat from the power supply board  126 . Each power supply assembly  40  is designed to be inserted into a pair of opposed top and bottom slots (formed by the top and bottom cold rails  116 , 118 , respectively) and held in place by being sandwiched between the wedge locks  124  and the corresponding top and bottom cold rails  116 , 118 , as shown in  FIGS. 18-19 . 
         [0042]    Referring to  FIG. 13 , each of the cold plates  86 , 88 , 128 , 130  can further include heat pipes  132  embedded in the cold plate. In the illustrated embodiment, these heat pipes  132  are only illustrated in connection with the primary cold plate  128  of the power supply assembly. These heat pipes  132  (shown in phantom in  FIG. 13 ) can be positioned to promote the transfer of heat in the desired direction. For example, when used in the PCB assemblies  38  for the lower cages  48 , the heat pipes  132  can be arranged to promote heat transfer upward and downward to the upper and lower thermal collectors  54 , 56 , respectively. When used in connection with the power supply assembly  40 , the heat pipes  132  can be embedded and positioned to promote transfer of heat upward to the top plate  110  and eventually to the upper heat sink  44 . 
         [0043]    Referring to  FIG. 16 , the upper heat sink  44  includes a distribution plate  134  and a series of upper fins  136  extending upward from the distribution plate  134 . The distribution plate  134  is positioned directly above the top plate  110  of the upper cage  50  and includes a series of heat pipes  138  that distribute heat in the distribution plate  134 . The illustrated heat pipes  138  are in multiple orientations, such as parallel to the front face  108 , perpendicular to the front face  108 , and oblique to the front face  108 . The illustrated upper fins  136  are arrange parallel to each other and perpendicular to the front face  108 . 
         [0044]    The upper cage  50  is designed to have a certain amount of vertical play relative to the frame  42  and relative to the upper heat sink  44 . For example, in the illustrated embodiment, the upper cage  50  can be moved vertically about five millimeters relative to the frame  42 . This vertical play allows the upper cage  50  to be moved vertically until the top plate  110  of the upper cage  50  contacts the distribution plate  134  of the upper heat sink  44 . Referring to  FIG. 17 , this vertical movement can be accomplished using a series of eccentric cams  140  mounted to the frame  42  and positioned under and in contact with the upper cage  50 . As best shown in  FIGS. 18-19 , rotation of the eccentric cams  140  will cause the upper cage  50  to move upwardly from a lowered position ( FIG. 18 ) to a raised position ( FIG. 19 ) to thereby facilitate the creation of contact between the top plate  110  and the distribution plate  134  of the upper heat sink  44 . Each of the eccentric cams  140  includes a cam actuator  142  that extends from a front surface of the frame  42  to facilitate rotation of the eccentric cams  140 . In the illustrated embodiment, the cam actuators  142  comprise hex heads that facilitate rotation of the eccentric cams  140  using a standard wrench. 
         [0045]    Although the invention has been described in detail with reference to certain preferred embodiments, variations and modifications exist within the scope and spirit of one or more independent aspects of the invention as described.