Patent Publication Number: US-2007102146-A1

Title: Cooling device for electronic components

Description:
FIELD  
      The present invention relates to a cooling device for electrical and electronic components and, in particular, a liquid heat exchanger.  
     BACKGROUND  
      Heat generating electrical or electrical components include for example memory chips, CPUs, voltage regulators, drivers, etc. and generate heat that is deleterious to their operation and the operation of other system components.  
      Fluid heat exchangers are used to conduct heat away from heat generating electrical or electrical components and into a passing fluid such as air. A fluid heat exchanger generally may include a thermal plate and a heat-dissipating portion. The thermal plate is installed in thermal communication with a heat source such as directly or indirectly on a heat generating electrical or electronic component. The heat-dissipating portion is thermally coupled to the thermal plate to conduct heat energy therefrom. Coolant fluid passes through the heat-dissipating portion to accept heat energy therefrom. Where liquid coolant fluid is used, for example, the liquid is pumped through a block, sometimes called a “water block”, forming at least part of the heat dissipating portion where the liquid accepts the heat energy and then the heated liquid is pumped to a heat sink located at some distance from the block. It will be appreciated that various liquid coolants are known such as freon, water, alcohols, glycols, etc.  
      General information concerning fluid heat exchangers, is contained in applicant&#39;s corresponding published application WO 03/007372, dated Jan. 23, 2003 and is incorporated herein by reference.  
     SUMMARY  
      In accordance with another broad aspect of the present invention, there is provided a fluid heat exchanger comprising: a base, a heat pipe including an evaporator portion thermally coupled to the base and a condenser portion; a coolant block portion thermally coupled to the condenser portion of the heat pipe, the coolant block portion including a liquid tight passage extending from a passage inlet to a passage outlet.  
      In accordance with another broad aspect of the present invention, there is provided a cooling system for a heat-generating component, the cooling system comprising: a fluid heat exchanger including a base, a heat pipe including an evaporator portion thermally coupled to the base and a condenser portion; a coolant block portion thermally coupled to the condenser portion of the heat pipe, the coolant block portion including a liquid tight passage extending from a passage inlet to a passage outlet.  
      It is to be understood that other aspects of the present invention will become readily apparent to those skilled in the art from the following detailed description, wherein various embodiments of the invention are shown and described by way of illustration. As will be realized, the invention is capable for other and different embodiments and its several details are capable of modification in various other respects, all without departing from the spirit and scope of the present invention. Accordingly the drawings and detailed description are to be regarded as illustrative in nature and not as restrictive. 
    
    
     DESCRIPTION OF THE DRAWINGS  
      Referring to the drawings wherein like reference numerals indicate similar parts throughout the several views, several aspects of the present invention are illustrated by way of example, and not by way of limitation, in detail in the figures, wherein:  
       FIG. 1  is a side elevation of an assembled fluid heat exchanger.  
       FIG. 2  is an end elevation of the fluid heat exchanger of  FIG. 1 .  
       FIG. 3  is a bottom plan view of the fluid heat exchanger of  FIG. 1 .  
       FIG. 4  is a top plan view of a fluid heat exchanger base and heat pipes with the coolant block portion removed.  
       FIG. 5  is a side elevation of the assembly of  FIG. 4 .  
       FIG. 6  is a schematic view of a cooling system for a heat-generating component. 
    
    
     DESCRIPTION OF THE VARIOUS EMBODIMENTS  
      The detailed description set forth below in connection with the appended drawings is intended as a description of various embodiments of the present invention and is not intended to represent the only embodiments contemplated by the inventor. The detailed description includes specific details for the purpose of providing a comprehensive understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without these specific details.  
      Referring to FIGS.  1  to  5 , a fluid heat exchanger  10  is shown that includes a base  12 , a coolant block portion  14  and one or more heat pipes  16 , each heat pipe including an evaporator portion  18  and a condenser portion  20 . The evaporator portion of each heat pipe is attached and thermally coupled to the base and the condenser portion of each heat pipe is attached and thermally coupled to coolant block portion  14 .  
      It is to be understood that fluid heat exchanger  10  may be used to conduct heat away from a heat-generating component such as, for example, a component of a computer or other electric or electronic device. In operation, base  12  is mounted in thermal communication with the heat generating component and heat is conveyed through base  12  to the heat pipes  16  and then to coolant block portion  14  where the heat is dissipated to a liquid coolant medium for further conveyance out of the fluid heat exchanger.  
      Base  12  may be formed in various ways and of various materials to permit mounting to accept heat energy from the heat generating component, to conduct thermal energy and to accept, support and be in thermal communication with heat pipes  16 . The heat pipes may be thermally coupled to and/or arranged relative to base  12  in various ways. In the illustrated embodiment, base  12  is formed about a portion of each heat pipe  16 , which portion thereby becomes the evaporator portion  18  of each heat pipe. To enhance operation of the heat exchanger, base  12  and heat pipe evaporator portions  18  may be formed and/or arranged such that elongate portions of the heat pipes pass through the base. For example base  12  may include an elongate dimension along which the heat pipes extend and are thermally coupled.  
      It will be appreciated that a heat pipe operates by phase change of a heat transfer, working medium between the heat pipe&#39;s evaporator portion  18  and condenser portion  20 . Heat pipes generally include a closed envelope in which heat transfer working medium is contained. The heat transfer is achieved by vaporization of the working medium at the evaporator portion by action of received heat energy and condensation of the gaseous working medium at condenser portion  20 , which is cooler due to its thermally conductive contact with portion  14  that permits dissipation of the heat energy. A circuit is set up within a heat pipe wherein working medium moves from the condenser portion to the evaporator portion by gravity flow or wicking action.  
      In the presently illustrated embodiment, the heat pipes are formed as hollow tubes. Heat pipes may take various forms. For example, heat pipes may be relatively straight or curved. In one embodiment, for example, one or more of the heat pipes may be L-shaped or U-shaped including an evaporator portion and an arm, defining the condenser portion, extending at an angle from the evaporator portion at one or both ends of the evaporator portion. The illustrated embodiment, for example, includes a heat pipe formed such that it has a first end  16 ′ and an opposite end  16 ″ and the first and opposite ends define condenser portions  20 , while the heat pipe&#39;s evaporator portion  20  is positioned along the length of the pipe between its ends.  
      While other numbers and configurations of heat pipes may be used as desired, in the illustrated embodiment of  FIGS. 4 and 5  there are three heat pipes  16   a,    16   b,    16   c  and each heat pipe includes an elongate evaporator portion (inside base  12 ) positioned between ends formed as heat pipe condenser portions  20   a,    20   b,    20   c.  In this way, evaporated working medium within the heat pipe may migrate to either end of the heat pipe to convey heat energy from the base to the coolant block portion. This may reduce the occurrence of heat pipe dry outs which sometimes occur in environments where the heat exchanger must operation under significant heat load. Ends  16 ′  16 ″ may be straight upstanding or curved. For example, in the illustrated embodiment, both ends are curved to each include a return portion extending substantially parallel to the evaporator portion. The curved end returns are positioned in side by side relation with one end  16 ′ running in direction opposite to the other end  16 ″ such that the heat exchanger forms a compact arrangement. In the illustrated embodiment, the plurality of heat pipes define a plurality of returned ends that may be curved and positioned in side by side, spaced apart relation and coolant block portion  14  may be thermally coupled to the arranged ends  16 ′  16 ″. The ends may be arranged substantially in a plane to facilitate connection to block portion  14 . In one embodiment, the planar configuration of ends  16 ′,  16 ″, portion  14  and base  12  may be substantially in parallel to provide a compact arrangement.  
      The heat pipes may be attached to and/or arranged relative to coolant block portion  14  in various ways. In one embodiment, a plurality of coolant blocks may be used into each of which at least some of the heat sink pipe condenser portions are connected and thermally coupled. Alternately, a single coolant block portion may be used. Where both ends of an elongate heat pipe are formed as condenser portions, the ends may be configured, as by curving, to each be mounted in a single coolant block portion  14 , which may reduce the overall size of the fluid heat exchanger. To facilitate operation of the heat exchanger, the heat pipe condenser portions may be formed such that elongate portions thereof are thermally coupled to the coolant block portion.  
      Coolant block portion  14 , in addition to its connection to heat pipes  16 , includes a body with one or more liquid tight passages extending therethrough. The passages provide for conduction of liquid coolant, such as one or more of water, a glycol, a freon, etc., from a passage inlet through the body of portion  14  to a passage outlet. Passages may be formed in various ways and configurations through coolant block portion  14  to permit flow of liquid coolant therethrough and heat-dissipating contact between the body of the coolant block portion and liquid coolant passing through the passages. Generally, a passage that provides expansive contact with body is desirable. In the illustrated embodiment, coolant block portion includes a passage  22  extending between barbs  24 . Passage  22  is formed to contain the liquid coolant in a liquid tight manner and channel it between the barbs. In the illustrated embodiment, passage  22  is formed as an open area below an upper body cap  14   a  and includes internal dividers  23  to define the passage and channel and direct the flow of coolant through the body.  
      Thermal coupling between the parts may be provided by casting, welding, soldering, press fitting, thermally conductive adhesives or fillers, and many other ways as will be apparent to a skilled person. In the illustrated embodiment, portion  14  is formed of two parts: an upper part  26  including passage  22  extending therethrough and a clamping part  28  that can be clamped against upper part  26  with the heat pipe condenser portions  20  secured therebetween, as by use of screws  30 . Corresponding grooves  32  may be formed in interfacing surfaces of upper part  26  and clamping part  28  to form channels into which the heat pipes may be secured. Thermally conductive fillers can be used between heat pipes  16  and upper part  26 . Of course, other modes of assembly and thermal coupling can be used, as desired.  
      Referring to  FIG. 6 , a computer cooling system  100  is shown for a heat-generating component  102  of the computer. The cooling system includes a fluid heat exchanger  110  including a base  112 , a coolant block portion  114  and a heat pipe  116 , each heat pipe including an evaporator portion  118  and a condenser portion  120 . The evaporator portion of each heat pipe is attached and thermally coupled to the base and the condenser portion of each heat pipe is attached and thermally coupled to coolant block portion  114 . Coolant block portion  114  includes a passage  122  to channel liquid coolant in a liquid tight manner between an inlet  124   a  and an outlet  124   b.    
      Fluid heat exchanger  110  is included in the system to conduct heat away from heat generating component  102 . To do so, base  112  is mounted in thermal communication with heat generating component  102  and heat is conveyed through base  112  to the heat pipes  116  and then to coolant block portion  114  where the heat is dissipated to a liquid coolant medium passing through passage  122  for further conveyance out of the fluid heat exchanger.  
      In the system, an inlet tube  140  may be connectable to inlet  124   a  and an outlet tube  142  may be connectable to outlet  124   b  to conduct the liquid coolant in a circuit between a heat sink  144  and coolant block portion  114 . The respective connections between inlet tube  140  and inlet  124   a  and between outlet tube  142  and outlet  124   b  may be liquid tight to avoid leakage of liquid coolant at these connection points.  
      The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to those embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the full scope consistent with the claims, wherein reference to an element in the singular, such as by use of the article “a” or “an” is not intended to mean “one and only one” unless specifically so stated, but rather “one or more”. All structural and functional equivalents to the elements of the various embodiments described throughout the disclosure that are know or later come to be known to those of ordinary skill in the art are intended to be encompassed by the elements of the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 USC 112, sixth paragraph, unless the element is expressly recited using the phrase “means for” or “step for”.