Abstract:
A heat dissipation apparatus includes a heat absorption device coupled to a board, the heat absorption device configured to absorb heat generated by an electrical device mounted on the board, a heat dispersion device configured discretely from the heat absorbing device and the board for dispersing heat input thereto and a heat transporting device coupled between the heat absorption device and the heat dispersion device for transporting heat absorbed by the heat absorption device to the heat dispersion device.

Description:
FIELD OF THE INVENTION 
   The present invention is directed generally to a method and apparatus for dispersing heat from high-power electronic devices and more particularly to a method and apparatus for transporting heat from high-power electronic devices to a radiator device for dispersion. 
   BACKGROUND OF THE INVENTION 
   As the power requirements for microprocessors increases due to increases in clock speeds and functionality, the amount of heat generated by the microprocessors also increases. The heat generated by the microprocessors must be removed from the location of the microprocessors in order for the microprocessors to function to their full potential. However, in systems that utilize multiple boards, each including multiple microprocessors, mounted within an enclosure that also houses electrical equipment such as disk drives and power supplies, prior art heat sinks are constrained to the available footprint size on the board and the distance or pitch between each board. As the power requirements of these microprocessors increases and the footprint size and board pitch decreases, prior art heat sinks are becoming less able to remove the heat generated by the microprocessors, thus impeding their performance. 
   SUMMARY OF THE INVENTION 
   The present invention is directed to a method and apparatus for dispersing heat from high-power electronic devices, preferably high-power electronic devices mounted on boards having minimized board pitches, where the space available for mounting adequate heat sinks to the boards is extremely limited or non-existent. The invention includes heat sinks mounted to the boards proximate the location of associated microprocessors, a heat pipe assembly configured to transport heat absorbed by the heat sinks away from the boards and a radiator device configured for dispersing the heat transported thereto by the heat pipe assembly from the heat sinks. The invention enables the increased amount of heat generated by the microprocessors to be moved away from the microprocessors and dispersed by the radiator device, which can be designed to be able to disperse an amount of heat that matches or exceed the amount of heat generated by the microprocessors. 
   According to one aspect of the invention, the heat dissipation apparatus includes a heat absorption device coupled to a board, the heat absorption device configured to absorb heat generated by an electrical device mounted on the board, a heat dispersion device configured discretely from the heat absorbing device and the board for dispersing heat input thereto and a heat transporting device coupled between the heat absorption device and the heat dispersion device for transporting heat absorbed by the heat absorption device to the heat dispersion device. 
   The heat dissipation device may further include a plurality of heat absorption devices coupled to the board, each of the plurality of heat absorption devices configured to absorb heat generated by an associated electrical device mounted on the board, and each of the plurality of heat absorption devices being coupled to the heat transporting device. The heat dissipation device may further include a second heat absorption device coupled to a second board, the second heat absorption device configured to absorb heat generated by an electrical device mounted on the second board, the second heat absorption device being coupled to the heat dispersion device through a second heat transporting device. 
   The heat transporting device may include a first heat transporting element extending from the heat absorption device and a second heat transporting element extending between the first heat transporting element and the heat dispersion device. The heat dispersion device may include a mount portion for coupling the heat dispersion device to the heat transporting device and a radiator device coupled to the mount portion for dispersing heat input to the heat dispersion device by the heat transporting device. The radiator device may include at least one heat transporting element extending from the mount portion of the heat dispersion device. The radiator device may further include at least one fin mounted on each of the at least one heat transporting elements. The first, second and third heat transporting elements may include heat pipes. The first heat transporting element, the second heat transporting element and the third heat transporting element may be in fluid communication with each other. The heat dissipation device may further include an enclosure, wherein the board is mounted to the enclosure in a first orientation and the heat dispersion device is mounted to the enclosure in a second orientation, the first orientation being non-parallel to the second orientation. A pitch between the first and second boards is at least 0.5″. The first orientation of the board may be approximately perpendicular to the second orientation of the heat dispersion device. 
   The heat dissipation device may further include an enclosure, wherein the board is mountable within a slot formed in the enclosure by fitting first and second edges of the board into the slot formed in the enclosure; the slot is formed from a heat absorbing material; the heat transporting device comprises a first heat transporting element extending from the heat absorption device to the first edge of the board and the heat dispersion device includes a radiator device coupled to the slot of the enclosure. The first heat transporting element transfers heat absorbed by the heat absorption device to the slot, which transfers the heat off of the board to the radiator device of the heat dispersion device. 
   According to yet another embodiment, a method of dispersing heat from an electrical device, includes: 
   A) absorbing heat generated by an electrical device mounted on a board; 
   B) transporting the heat absorbed by the heat absorption device away from the electrical device and off of the board to a heat dispersion device configured discretely from the heat absorbing device and the board; and 
   C) dispersing the heat input to the heat dispersion device. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other features of the invention will become more readily apparent from the following detailed description when read together with the accompanying drawings, in which: 
       FIG. 1  is perspective view of a heat dispersion system in accordance with the present invention; 
       FIG. 2  is a side view of the heat dispersion system shown in  FIG. 1  in accordance with the present invention; 
       FIG. 3  is a side view of and alternative embodiment of the heat dispersion system in accordance with the present invention; 
       FIG. 4  is perspective view of the heat dispersion system, including multiple boards mounted to the radiator device of the heat dispersion system in accordance with the present invention; 
       FIG. 5  is a front view of the heat dispersion system shown in  FIG. 4  in accordance with the present invention; 
       FIG. 6  is a perspective view of an enclosure into which the heat dispersion of the present invention may be mounted; and 
       FIG. 7  is a flow diagram showing the steps involved in the operation of the heat dispersion system in accordance with the present invention; and 
       FIG. 8  is a side view of an alternative embodiment of the heat dispersion system in accordance with the present invention. 
   

   DETAILED DESCRIPTION 
   Shown in  FIGS. 1 and 2 , which are perspective and side views, respectively, is a heat dissipation device  10  in accordance with a preferred embodiment of the present invention. Heat dissipation device  10  includes heat sinks  12   a - 12   d  mounted on a board  14  on which is mounted microprocessors and other electrical components (not shown) which are used to control the operation of other devices, such as disk drives. Each of the heat sinks  12   a - 12   d  preferably includes a finned extruded body of a metal, such as aluminum, copper or magnesium, mounted on the board  14  in contact with an upper surface of a microprocessor, which are not shown in  FIG. 1 , as they are located under the heat sinks  12   a - 12   d . Heat sinks  12   a - 12   d  operate to absorb heat generated by the associated microprocessors during their operation. While this description and the figures describe the invention as having four heat sinks, each associated with a microprocessor, it will be understood that any number of heat sinks may be used in the invention to absorb heat generated by any type of heat generating device mounted on the board. 
   Typically, the board  14  is mounted within an enclosure such as that shown at  100 ,  FIG. 6 . The board  14  is mounted in slots  102  of the enclosure  100 , and, as described below, a plurality of boards may be mounted in slots  102  of enclosure  100 . In such a configuration, the board  14  may be utilized for controlling communications between microprocessors and a bank of disk drives (not shown). Preferably, fans are mounted above the enclosure  100  for the purpose of providing forced convection parallel to the boards. However, it will be understood that the fans could be mounted below the enclosure or between the boards and the radiator device  18 . The radiator device  18  is preferably mounted in the enclosure in a perpendicular relationship with respect to the boards and the flow of air from the fans. This perpendicular orientation maximizes the heat dissipation capabilities of the radiator device by placing the greatest cross-section of the radiator device in the direct flow of the fans. 
   As shown in  FIGS. 1 and 2 , a heat transporting device  16  couples the heat sinks  12   a - 12   d  to the radiator device  18 . Heat transporting device  16  includes heat transport elements  20   a - 20   d  which are embedded within each of the heat sinks  12   a - 12   d , respectively, and extend from the associated heat sink  12   a - 12   d  to a coupling  22   a - 22   d , respectively. Each element  20   a - 20   d  is coupled to element  24  of heat transporting device  16  by its associated coupling  22   a - 22   d . Each of couplings  22   a - 22   d  preferably are formed from a heat absorbing material, such as aluminum, copper or magnesium, and are friction fit or clamped to both its associated heat transport element  20   a - 20   d  and the element  24 . Element  24  couples each of the heat transport elements  20   a - 20   d  and consequently each heat sink  12   a - 12   d , to a mount  26  of the radiator device  18 . 
   As described above, the enclosure  100  is capable of housing a number of boards  14 . Multiple boards may be used to provide access to multiple processors, which enables the overall system to access and control a greater number of disk drives or other electrical devices. Enclosure  100  provides a connection point between the boards  14  and the processors and disk drives associated with the overall system. Accordingly, enclosure  100  is designed to enable the easy installment and removal of the boards for the purposes of maintenance, upgrading, etc. Since the radiator device  16  is mounted to the enclosure  100 , when boards  14  are installed or removed from the enclosure  100 , the connection between the heat transporting device  16  and the radiator device  18  must be easy to engage and disengage. 
   In the preferred embodiment, element  24  of heat transporting device  16  is coupled to the mount  26  of the radiator device by a locking fitting  28 , which may include a threaded attachment coupling, a latch, or any other suitable connection device that provide a secure, but releasable, connection between the heat transporting device  16  and radiator device  18  and which enables heat to be efficiently transferred from the heat transporting device  16  to radiator device  18 . 
   Radiator device  18  includes a number of heat transport elements  30 , which extend between mount  26  and a bracket  32 , which is used, along with mount  26 , to attach the radiator device  18  to the enclosure  100 . Each element  30  is embedded within a fin stack  34 , which provides increased surface area for heat transferred from the heat transporting device  16  to radiator device  18  to be dispersed via natural or forced convection. 
   Heat transport elements  20   a - 20   d ,  24  and  30  preferably comprise heat pipes, which are two-phase heat transfer devices that have an extremely high effective thermal conductivity. The construction and operation of heat pipes are known in the art. Generally, a typical heat pipe has an inner surface that is lines with a capillary wicking material. The heat pipe is filled with a working fluid, such as water, acetone or methanol. In the case of water, it is preferred that a non-electrically conductive form of water be used, such as deionized water. Heat is absorbed in an evaporator region of the heat pipe by vaporizing the working fluid. The vapor transports the heat to a condenser region, where the vapor condenses, releasing the heat. The condensed working fluid is pumped back to the evaporator region by gravity or capillary action. 
   In the preferred embodiment, for ease of manufacture, the heat transport elements  20   a - 20   d ,  24  and  30  are discrete, self contained heat pipes that transfer heat to each other by absorbing heat that the upstream heat pipe releases. However, it will be understood that (1) heat transport elements  20   a - 20   d ,  24  and  30  could be formed as a single, continuous heat pipe; (2) heat transport elements  20   a - 20   d  and heat transport element  24  could be formed as a single, continuous heat pipe; or (3) heat transport element  24  and heat transport elements  30  could be formed as a single, continuous heat pipe. In the first and second cases, a single, continuous heat pipe could be formed that begins at the heat sink furthest away from the mount  26  and loops through each of the heat sinks on its way to the attachment point between the heat transporting device and the radiator device. In the first and third cases, a fitting  28  that enables the fluid within the heat pipes to flow between heat transport elements  24  and  30 , through mount  26 , would be required. 
   In operation, as illustrated in flow diagram  60 ,  FIG. 7 , heat generated by a microprocessor mounted on the board  14  is absorbed by its associated heat sink  12   a - 12   d , Step  62 . For the purpose of this example, the microprocessor is associated with heat sink  12   d . As the heat sink  12   d  absorbs the heat generated by the microprocessor, it is transported away from the heat sink  12   d  by the heat transporting device  16 , Step  64 . In particular, the heat is transported through heat transport element  20   d  of heat transporting device  16  to heat transport element  24  of heat transporting device  16  through coupling  22   d . The heat is transferred by the heat transporting device  16  to the radiator device  18 , Step  66 . The heat is received by the radiator device through locking fitting  28  and mount  26  into one or more heat transport elements  30 , where it is transferred to fin stacks  34  and dispersed into the ambient air, Step  68 . In the preferred embodiment, the dispersion of heat by the radiator device  18  is aided through the use of fans that provide forced convection. However, it will be understood that the dispersion may also take place through natural convection. 
   An alternative embodiment of the invention is shown at  36 ,  FIG. 3 . In this embodiment, an additional heat sink  12   e  is serially connected to element  20   a  embedded in heat sink  12   a  through its own element  20   e  which is embedded in heat sink  12   e . Heat absorbed by the heat sink  12   e  is transported to element  24  of heat transporting device  16  through both element  12   e  and element  12   a . The heat absorbed in heat sink  12   e  is then transported to radiator device  18  in the manner described above. 
     FIGS. 4 and 5  show a perspective and front view, respectively, of the present invention in which a plurality of boards is coupled to radiator device  18 . As shown in  FIGS. 4 and 5 , boards  14   a ,  14   b ,  14   c  . . .  14   n  are coupled to mount  26  of the radiator device. Although not shown in  FIGS. 4 and 5 , these boards would be mounted in slots  102  of the enclosure  100 . Each of the boards  14   a ,  14   b ,  14   c  . . .  14   n  are coupled to the mount  26  via its locking fitting  28   a ,  28   b ,  28   c  . . .  28   n , respectively. Although only shown on board  14   a , each board includes heat sinks and an associated heat transporting device  16  for transporting heat from the associated heat sinks to the radiator device  18 . 
   As can be seen in  FIGS. 4 and 5 , the boards  14   a ,  14   b ,  14   c  . . .  14   n  are mounted very closely together in order to increase the number of boards that can be mounted in a single enclosure. In the preferred embodiment, the distance between the boards, or the board pitch, is in the range of at least 0.5″ to 3.0″. The configuration of the heat sinks and heat transporting device of the present invention is such that it does not increase the thickness of the board and therefore does not increase the board pitch. Accordingly, the enclosure into which the boards are mounted need not be reconfigured to accept boards that utilize the heat dissipation device of the present invention. 
   In an alternative embodiment, shown at  110  in  FIG. 8  the heat transporting device  116  includes a heat transport element  130 , such as a heat pipe, built into the top edge of the board  114  such that it directly contacts the slot  102  of the enclosure. For simplicity, only the slot  102  is shown in  FIG. 8 . In this embodiment, the slots  102  preferably are formed from a heat absorbing material, such as aluminum, copper or magnesium. The heat transport element  130  of radiator device  118  is mounted to the enclosure  100  in contact with the slots  102 . Heat transport elements  120   a - 120   d  transport heat to heat transport element  124 , which transports the heat to the heat transport element  130  built into the edge of the board. The heat is then transferred across the slots to the heat transport element  130  of radiator device  18 . The heat is then dispersed by the radiator device  18 . This embodiment enables the boards  14  to be installed into and removed from the enclosure  100  without any additional connections between the heat transporting device  16  and the radiator device  18 . 
   Accordingly, the present invention provides a heat dissipation device that is capable of removing the increased amounts of heat generated by high-powered electrical devices. The heat dissipation device provides increased heat dispersion capabilities by transporting the heat away from the electrical devices to a discrete radiator device, which provides increased surface area, thus enabling the device to disperse heat more quickly and efficiently than prior art devices. 
   The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. For example, while in the preferred embodiment, the heat transporting elements are described as comprising heat pipes, it will be understood that any type of system that can efficiently and effectively transport heat from the heat sinks to the radiator device may be utilized. For example, the heat transporting elements may include a fluid cooling system which circulates a fluid, such as water, through each of the heat sinks and the radiator device. The fluid absorbs heat as it passes through the heat sinks and transports it to the radiator device, where the heat is dispersed. The cooled liquid is circulated back to the heat sinks via a separate return route, such that the entire system is a loop that continuously circulates the fluid to transport the heat generated by the processors and absorbed by the heat sinks away from the board to be dispersed through the radiator device. Furthermore, it will be understood that the invention may be utilized in any type of electrical system where increased heat dissipation is needed to remove heat generated by high-power devices. The present embodiments are therefore to be considered in respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of the equivalency of the claims are therefore intended to be embraced therein.