Abstract:
A field-replaceable active pumped liquid heat sink module includes a front portion and a back portion, each including a liquid pump, a radiator, an optional receiver, and a cold plate heat exchanger, all of which are connected together in a liquid pump loop through which a coolant such as water is circulated. The liquid pump, radiator, optional receiver and cold plate heat exchanger are in a liquid pump loop and are self-contained in a field-replaceable active pumped liquid heat sink module.

Description:
FIELD OF THE INVENTION 
   The present invention is related to heat sinks for removing heat from electronic components such as integrated circuit processors. 
   BACKGROUND OF THE INVENTION 
   Removal of heat has become one of the most important challenging issues facing computer system designers today. As the rate of power dissipation from electronics components such as high performance server processors continues to increase, standard conduction and forced-air convection fan air cooling techniques no longer provide adequate cooling for such sophisticated electronic components. The reliability of the electronic system suffers if high temperatures at hot spot locations are permitted to persist. Conventional thermal control schemes such as air cooling with fans, thermoelectric cooling, heat pipes, and passive vapor chambers have either reached their practical application limit or are soon to become impractical for high power electronic components such as computer server processors. When standard cooling methods are no longer adequate, computer manufacturers have to reduce the frequency of their processors to match the capacity of existing cooling apparatus. Furthermore, reliability can be compromised due to inadequate cooling using an existing cooling apparatus, or product release delayed until a reliable cooling apparatus for removal of heat from high heat dissipating processors can be made available. 
   The computer industry is seriously considering utilizing active liquid cooling as an alternative to conventional passive air cooling for high performance and high power processors. A number of attempts to incorporate liquid for cooling of high powered processors in the form of submerged liquid, liquid spray cooling, refrigeration cooling, and the like have been attempted in the past, but none of the existing active liquid cooling solutions has been utilized outside of specific design conditions. Additionally, these cooling solutions, while effective, can include a relatively high number of moving parts that can lead to increased product and maintenance costs. 
   What is desired, therefore, is a field-replaceable heat sink module that employs active liquid cooling, but has the same appearance as a traditional air-cooling heat sink, is sturdy, reliable, compact, simple to use, relatively inexpensive, and can be effectively employed in a wide range of applications. 
   SUMMARY OF THE INVENTION 
   According to an embodiment of the present invention, a field and/or customer replaceable integrated active pumped liquid heat sink module is suitable for thermal management of high heat dissipation in electronic components such as server processors. The field-replaceable integrated active pumped liquid heat sink module is self-contained and is specifically designed to have physical dimensions similar to those of a standard air-based cooling system, such as a finned heat sink or a heat pipe. As a result, the field replaceable integrated active liquid-pumped heat sink module can be utilized in existing electronic systems without the need for board or cabinet/rack modification or the “plumbing” associated with prior art liquid-based cooling systems. 
   According to an embodiment of the present invention, a field-replaceable active pumped liquid heat sink module includes a “front” and a “back” portion, each including a liquid pump, a radiator, an optional receiver, and a cold plate heat exchanger, all of which are connected together in a liquid pump loop through which a coolant such as water is circulated. The liquid pump, radiator, optional receiver and cold plate heat exchanger are in a liquid pump loop and are self-contained in a field-replaceable active pumped liquid heat sink module. 
   From the view point of the end user, the entire liquid pump apparatus is hermetically-sealed and contained in the heat sink module and besides the electric wires needed to power up the liquid pump, there is no difference in external appearance of a conventional heat sink and the heat sink module of the current invention. The cold plate heat exchanger can be positioned in thermal contact with a heat source (such as the lid of a processor) of an electronic component, that is to be cooled. 
   As is understood by those of ordinary skill in the art, a liquid pump pumps the coolant out of a radiator. The heat of the high temperature coolant is removed in the radiator by the air blown by a system fan. In the radiator, the coolant is allowed to cool before being conveyed to a receiver. From the optional receiver, the coolant liquid is drawn back into the pump, out of which the liquid coolant passes into a cold plate heat exchanger. The liquid coolant is heated up in the cold plate heat exchanger and in the process absorbs heat from heat source (such as a server processor) to produce the desired cooling effect. From the radiator heat exchanger the coolant liquid is drawn back into pump to begin another cycle through pumped liquid cycle. 
   The field-replaceable integrated active-pumped liquid heat sink module of the present invention is a modified liquid-based cooling system and therefore provides the cooling capacity of prior art liquid-based cooling systems. However, unlike prior art liquid-based cooling systems, the field replaceable integrated active liquid pumped heat sink module of the present invention is modular and self-contained and is therefore field and/or customer replaceable with minimal effort using standard tools. In addition, unlike prior art liquid-based cooling systems, the field replaceable integrated active liquid-pumped heat sink module of the present invention is capable of being attached directly to the components (such as processors) that need cooling. In addition the field replaceable integrated active liquid-pumped heat sink module of the present invention is compact and simple in both operation and installation, with minimal parts to fail or break and minimal added complexity. Therefore the field replaceable integrated active liquid pumped heat sink module of the invention is sturdy and reliable. 
   The foregoing and other features, utilities and advantages of the invention will be apparent from the following more particular description of an embodiment of the invention as illustrated in the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows two cross-sectional views and a bottom view of a unitary field-replaceable active integrated liquid pump heat sink module according to an embodiment of the present invention; 
       FIG. 2  shows two cross-sectional views and a bottom view of a “front” portion of a multi-component field-replaceable active integrated liquid pump heat sink module according to an embodiment of the present invention; and 
       FIG. 3  shows two cross-sectional views and a bottom view of a “back” portion of a multi-component field-replaceable active integrated liquid pump heat sink module according to an embodiment of the present invention. 
   

   DETAILED DESCRIPTION 
   Referring now to  FIG. 1 , a first cross-sectional view  100  of a unitary field-replaceable active integrated liquid pump heat sink module according to an embodiment of the present invention includes a heat sink casing  114 , which is typically fabricated out of aluminum, copper, or alloys thereof, or other similar metals or alloys, and is about 0.25 inches thick. The overall dimensions of the heat sink casing are typically about 5.0 inches by 3.0 inches by 1.75 inches in a unitary embodiment, and about 7.0 inches by 5.0 by 1.75 inches in a multi-component embodiment, but can of course be changed as desired for a particular application. A cold plate heat exchanger  106  is embedded into the heat sink casing  114 , such that only a small thickness of material separates the cold plate heat exchanger  106  from the top surface of an integrated circuit processor (not shown in  FIG. 1 ) or other integrated circuit so that the maximum amount of heat can be removed. The remaining thickness at the bottom of the heat sink casing  114  shown in  FIG. 1  is between about 2.0 and 5.0 mm, but this range can also be changed as desired for a particular application. Cold plate heat exchangers are known in the art. A suitable cold plate heat exchanger would be a micro-channel heat exchanger, but other such cold plate heat exchangers could also be used. A hot liquid output line  118  is coupled to a radiator heat exchanger  120 . The hot liquid output line  118  is fabricated out of copper or aluminum. The dimensions of the hot liquid output line  118  are about 1.5 inches long by about 0.125 inches, outside diameter, but these dimensions are tailored to the form factor of the overall heat sink casing. The wall thickness of the hot liquid output line  118  is between 1.0 and 2.0 mm. The dimensions of the hot liquid output line  118  are maintained for the other liquid lines throughout the radiator heat exchanger  120 . The fluid lines in the radiator heat exchanger  120  are separated by a number of radiator fins  122 , which are fabricated out of aluminum or copper. The radiator fins  122  can be any dimensions required for a required form factor, but are typically about 4.0 inches long and about 0.125 inches thick. A fluid such as water or a mixture of water and glycol or other such media flows through the lines in the radiator heat exchanger  120 , and is gradually cooled without any phase change. The fluid is fully cooled at the uppermost line in the radiator heat exchanger  120  and emerges as the cold liquid return line  124  once fully cooled. In a typical application, the temperature of the fluid in the hot liquid output line  118  could be as high as 110° C., and, with proper air flow from an accompanying fan (not shown in  FIG. 1 ) the temperature of the fluid in the cold liquid return line  124  can be as low as 25° C. The cold liquid return line  124  is coupled to the input port of a liquid pump  126 . In accordance with an embodiment of the present invention, the liquid pump  126  is one of several new generation pumps that are relatively small, on the order of 1.5 inches in diameter and 3.0 to 4.0 inches long, although other dimension pumps can of course be used to fit a particular form factor. A suitable pump  126  for the unitary heat sink embodiment shown in  FIG. 1  is a brushless miniature spherical pump. A miniature diaphragm pump or a positive displacement pump could also be used. The output port of liquid pump  126  is coupled to the cold liquid input line  116 , which in turn is coupled to the input port of the cold plate heat exchanger  106  to complete the closed liquid flow path. Electrical connections  132  are provided to activate the liquid pump  126 , which are the only outside connections required by the unitary heat sink module according to the present invention. The liquid pump  126  typically consumes about 10.0 watts of power, and is energized by a 12.0 volt connection and a ground connection. In the multi-component embodiment, each liquid pump consumes about 10.0 watts of power. 
   A second cross-sectional view  102  of a unitary field-replaceable active integrated liquid pump heat sink module according to an embodiment of the present invention is also shown in  FIG. 1 , which is orthogonal to cross-sectional view  100 . Cross-sectional view  102  allows further detail of the heat sink module to be shown. The cross-sectional view of the heat sink casing  114  shows embedded cold plate heat exchanger  106 . The cross-sectional view of the cold plate heat exchanger allows a view of the cold plate heat exchanger liquid channel  106 . The liquid channel  106  is only a representative view of a slice through cold plate heat exchanger  106  at a particular plane therethrough, and thus the actual ports engaging the hot liquid output line  118  and cold liquid input line  116  are not shown. In cross-sectional view  102 , the individual radiator heat exchanger liquid flow channels  128  are visible, as well as a side view of one course of the radiator heat exchanger fin plates  130 . 
   A second bottom view  104  of a unitary field-replaceable active integrated liquid pump heat sink module according to an embodiment of the present invention is also shown in  FIG. 1 . The bottom view  104  shows the “footprint” of the heat sink base plate  110 , as well as the footprint of the cold plate heat exchanger base plate  112 , that will reside on top of the lid of the integrated circuit processor or other circuit. Note that in bottom view  104 , the actual cold plate heat exchanger base plate  112  is covered by a thin layer of heat sink casing material. Two cross-sectional lines  100  and  102  are shown in the bottom view  104 , representing the relative cross-sectional cuts for first and second cross-sectional views  100  and  102 . 
   Referring now generally to  FIG. 2 , a first portion of a multi-component field-replaceable active integrated liquid pump heat sink module is shown according to an embodiment of the present invention. It is important to note in  FIG. 2 , that the “100” series of identification numerals referred to in  FIG. 1  generally correspond to the “200” series shown in  FIG. 2 . In addition, the dimensions and selection of the components are generally the same, except as noted below. 
   Cross-sectional view  200  only depicts the components in the “front” portion of the heat sink module. The components in the “back” portion of the same heat sink module are described below with respect to  FIG. 3 . Thus, shown in  FIG. 2  are the heat sink casing  214 , a first cold plate heat exchanger  206  embedded into the heat sink casing  214 , such that only a small thickness of material separates the cold plate heat exchanger  206  from the top surface of a first integrated circuit processor (not shown in  FIG. 2 ) or other integrated circuit. A first hot liquid output line  218  is coupled to a first radiator heat exchanger  220 . The dimensions of the hot liquid output line  118  are about 1.5 inches long by 0.125 inches, outside diameter, but these dimensions are tailored to the form factor of the overall heat sink casing. Most pertinently, the dimensions are adjusted to make sure that the first radiator heat exchanger  220  and the second radiator heat exchanger  320  (described below) both fit into the same heat sink module. The dimensions of the hot liquid output line  218  are maintained for the remaining fluid lines throughout the radiator heat exchanger  220 . The fluid lines in the radiator heat exchanger  220  are separated by a number of radiator fins  222 . The cold liquid return line  224  is coupled to the input port of a first liquid pump  226 . The output port of the first liquid pump  226  is coupled to the cold liquid input line  216 , which in turn is coupled to the input port of the first cold plate heat exchanger  206  to complete the closed liquid flow path. Electrical connections  232  are provided to activate the first liquid pump  226 . 
   A second cross-sectional view  202  of a multi-component field-replaceable active integrated liquid pump heat sink module according to an embodiment of the present invention is also shown in  FIG. 2 , which is orthogonal to cross-sectional view  200 . Cross-sectional view  202  allows further detail of the heat sink module to be shown. The cross-sectional view of the heat sink casing  214  shows embedded cold plate heat exchanger  206 . The cross-sectional view of the cold plate heat exchanger allows a view of the cold plate heat exchanger liquid channel  206 . In cross-sectional view  202 , the individual radiator heat exchanger liquid flow channels  228  are visible, as well as a side view of one course of the radiator heat exchanger fin plates  230 . There are two sets of liquid flow channels and fin plates visible in cross-sectional view  202  corresponding to the components in the front and back portions multi-component heat sink module. 
   A second bottom view  204  of the multi-component field-replaceable active integrated liquid pump heat sink module according to an embodiment of the present invention is also shown in  FIG. 2 . The bottom view  204  shows the footprint of the heat sink base plate  210 , as well as the footprint of the first and second cold plate heat exchanger base plates  212  and  312 , that will reside on top of the lids of two integrated circuit processors or other circuits. Two cross-sectional lines  200  and  202  are shown in the bottom view  204 , representing the relative cross-sectional cuts for first and second cross-sectional views  200  and  202 . It is important to note that cross-sectional line  200  may have to be adjusted up or down in bottom view  204  to provide the cross-sectional views actually shown in  FIGS. 2 and 3 . This adjustment may be necessary due to the exact physical placement of liquid pumps  226  and  326  within the heat sink module. 
   Referring now generally to  FIG. 3 , a second portion of a multi-component field-replaceable active integrated liquid pump heat sink module is shown according to an embodiment of the present invention. It is important to note in  FIG. 3 , that the “100” series of identification numerals referred to in FIG.  1  generally correspond to the “300” series shown in  FIG. 3 . In addition, the dimensions and selection of the components are generally the same, except for the same shared heat sink casing  214  and the same shared heat sink base plate  210 , and as noted below. 
   Cross-sectional view  300  only depicts the components in the “back” portion of the heat sink module. Thus, shown in  FIG. 3  are the heat sink casing  314 , a second cold plate heat exchanger  306  embedded into the heat sink casing  314 , such that only a small thickness of material separates the cold plate heat exchanger  206  from the top surface of a second integrated circuit processor (not shown in  FIG. 3 ) or other integrated circuit. A second hot liquid output line  318  is coupled to a second radiator heat exchanger  320 . The fluid lines in the radiator heat exchanger  320  are separated by a number of radiator fins  322 . The cold liquid return line  324  is coupled to the input port of a second liquid pump  326 . The output port of the second liquid pump  326  is coupled to the cold liquid input line  316 , which in turn is coupled to the input port of the second cold plate heat exchanger  306  to complete the closed liquid flow path. Electrical connections  332  are provided to activate the first liquid pump  326 . 
   A second cross-sectional view  302  of a multi-component field-replaceable active integrated liquid pump heat sink module according to an embodiment of the present invention is also shown in  FIG. 3 , which is orthogonal to cross-sectional view  300 . The cross-sectional view of the heat sink casing  214  shows a second embedded cold plate heat exchanger  306 . The cross-sectional view of the cold plate heat exchanger allows a view of the cold plate heat exchanger liquid channel  306 . In cross-sectional view  302 , the individual radiator heat exchanger liquid flow channels  328  are visible, as well as a side view of one course of the radiator heat exchanger fin plates  330 . There are two sets of liquid flow channels and fin plates visible in cross-sectional view  302  corresponding to the components in the front and back portions multi-component heat sink module. 
   A second bottom view  304  of the multi-component field-replaceable active integrated liquid pump heat sink module according to an embodiment of the present invention is also shown in  FIG. 3 . The bottom view  204  shows the footprint of the heat sink base plate  210 , as well as the footprint of the first and second cold plate heat exchanger base plates  212  and  312 , that will reside on top of the lids of two integrated circuit processors or other circuits. Two cross-sectional lines  300  and  302  are shown in the bottom view  304 , representing the relative cross-sectional cuts for first and second cross-sectional views  200  and  302 . It is important to note that cross-sectional line  300  may have to be adjusted up or down in bottom view  304  to provide the cross-sectional views actually shown in  FIGS. 2 and 3 . This adjustment may be necessary due to the exact physical placement of liquid pumps  226  and  326  within the heat sink module. While the invention has been particularly shown and described with reference to embodiments thereof, it will be understood by those skilled in the art that various other changes in the form and details may be made without departing from the spirit and scope of the invention. It should be understood that this description has been made by way of example, and that the invention is defined by the scope of the following claims.