Abstract:
A heatsink with an internal cavity for liquid cooling includes: a first part having a first group of fins extending into the internal cavity; a second part attached to the first part so that the internal cavity is formed, the second part having a second group of fins that extend into the internal cavity and that are configured to fit among the first group of fins; an inlet into the internal cavity on at least one of the first and second parts; and an outlet from the internal cavity on at least one of the first and second parts.

Description:
BACKGROUND 
       [0001]    Some electric and electronic components require some form of cooling during use. In certain scenarios, active cooling is provided by bringing a stream of air or a flow of liquid (i.e., coolant) into thermal contact with the heat-generating device(s). Heat is absorbed by the air/coolant as it passes by the heated region, and thermal energy is then dissipated from the cooling medium in some way, such as using a radiator. 
         [0002]    In liquid-cooling systems, the coolant is usually circulated through one or more conduits that are designed to absorb the generated heat and transfer it to the medium flowing inside. Some such conduits have internal structures designed to improve the heat transfer into the coolant. However, manufacturing such conduits with internal structures can be challenging. 
       SUMMARY 
       [0003]    In a first aspect, a heatsink with an internal cavity for liquid cooling includes: a first part having a first group of fins extending into the internal cavity; a second part attached to the first part so that the internal cavity is formed, the second part having a second group of fins that extend into the internal cavity and that are configured to fit among the first group of fins; an inlet into the internal cavity on at least one of the first and second parts; and an outlet from the internal cavity on at least one of the first and second parts. 
         [0004]    Implementations can include any or all of the following features. The first group of fins comprise first pins arranged in a first array, and wherein the second group of fins comprise second pins arranged in a second array. The first array has rows that are staggered from rows in the second array, and wherein the first array has columns that are staggered from columns in the second array. One of the columns in the first array has N complete pins and wherein a corresponding column in the second array has N−1 complete pins and two half-pins, the two half-pins located above and below, respectively, the N−1 complete pins. The first part has the internal cavity, and wherein the second part is a substantially flat lid that closes the internal cavity when the second part is attached to the first part. The inlet and the outlet are located on the first part. The inlet makes a turn before reaching the internal cavity and wherein the heatsink has a fin at the turn. The outlet makes a turn after the internal cavity and wherein the heatsink has a fin at the turn. The heatsink comprises a housing formed by the first and second parts that is substantially flat, the heatsink further comprising a tab on an edge of the housing, the tab configured for positioning springs on the housing for holding electric components. Each spring comprises a clip configured for holding a pair of electric components, one on each side of the housing. The first group of fins is oppositely oriented than the second group of pins. The first group of fins and the second group of fins fully overlap each other. The first and second groups of fins have identical shapes. The fins are pins and the identical shapes comprise oval profiles. Each of the first and second groups of fins are pins, and wherein each of the pins has a draft. The inlet is configured for connection to a first manifold having at least another heatsink attached, wherein the outlet is configured for connection to a second manifold that also has at least the other heatsink attached, and wherein the first and second manifolds provide parallel flows of coolant through the heatsink and the other heatsink. The first and second parts consist of respective first and second cast parts. The first and second parts are made of aluminum. 
         [0005]    In a second aspect, a method of manufacturing a heatsink with an internal cavity for liquid cooling includes: casting a first part having a first group of fins extending into the internal cavity; casting a second part configured to be attached to the first part so that the internal cavity is formed, the second part having a second group of fins that extend into the internal cavity and that are configured to fit among the first group of fins, wherein an inlet into the internal cavity is located on at least one of the first and second parts, and wherein an outlet from the internal cavity on at least one of the first and second parts; and attaching the second part to the first part. 
         [0006]    Implementations can include any or all of the following features. The first group of fins comprise first pins arranged in a first array, wherein the second group of fins comprise second pins arranged in a second array, wherein the first array has rows that are staggered from rows in the second array, wherein the first array has columns that are staggered from columns in the second array. One of the columns in the first array has N complete pins and wherein a corresponding column in the second array has N−1 complete pins and two half-pins, the two half-pins located above and below, respectively, the N−1 complete pins. The first and second parts are cast from aluminum. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0007]      FIG. 1  shows an example of a heatsink that includes a body and a lid. 
           [0008]      FIG. 2  shows an example of the body from  FIG. 1 . 
           [0009]      FIG. 3  shows an example of the body and the lid from  FIG. 1  being assembled to form the heatsink. 
           [0010]      FIG. 4  shows an example of a heatsink having components attached by springs. 
           [0011]      FIG. 5  shows an assembly of three heatsinks connected to manifolds. 
           [0012]      FIG. 6  shows an example cross section of the heatsink from  FIG. 1  after assembly. 
           [0013]      FIG. 7  shows an example of a process for manufacturing a heatsink. 
           [0014]      FIG. 8  shows another example of a heatsink that includes a body and a lid. 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    This document describes examples of systems and techniques for effectively cooling electric or electronic components using a heatsink. A process of manufacturing a heatsink so that it has an advantageous internal pattern of fins is also described. For example, one or more heatsinks can be installed in an electric vehicle to remove heat from components of the electric powertrain. 
         [0016]      FIG. 1  shows an example of a heatsink  100  that includes a body  102  and a lid  104 . The body has a hollow portion  106  that has a number of fins configured to facilitate flow of coolant, here fins  108 . The fins are arranged in a regular pattern (e.g., an array), here in rows of fins, where each fin is also part of a corresponding column of fins. For example, a particular column has intermediate fins  108 B, C and D, and corresponding half-fins  108 A and  108 E on top of, and below, the column, respectively. 
         [0017]    The body  102  also has an inlet  110  and an outlet  112 . The inlet and outlet provide fluid access to an internal cavity that is formed by the hollow portion  106  when the lid  104  is attached to the body. The location of the inlet and outlet in this example are illustrative only, and in other implementations, the inlet and/or the outlet can be in a different location. As another example, the heatsink can have more than one inlet and/or outlet. Each of the inlet and outlet has a corresponding fin  114  or  116 . 
         [0018]    The lid  104  has fins  118  that are configured to fit among the fins  108  of the body  102 . Similar to the fins of the body, the fins of the lid are arranged in a regular pattern (e.g., an array), here in rows of fins, where each fin is also part of a corresponding column of fins. Unlike the body fins, however, the lid fins have no half-fins in this example. Rather, a first column  118 A of the fins  118  is configured to fit on one side of the fins  108 A-E when the heatsink is assembled, and another column  1188  is configured to fit on the other side of the fins  108 A-E. That is, the fin rows on the body are here staggered from the fin rows on the lid, and the fin columns on the body are here staggered from the fin columns on the lid. 
         [0019]    In other implementations, the hollow portion  106  can be distributed between multiple components. For example, each of two body portions can have a respective half of the hollow portion, so as to form the internal cavity when assembled. Also, the numbers of fins in this example are illustrative only, and in other implementations, the heatsink can have different numbers of fins and/or half-fins. As another example, the columns that have half-fins can instead be on the lid, or can be distributed between the body and the lid. 
         [0020]      FIG. 2  shows an example of the body  102  from  FIG. 1 . This view shows an example of the inlet  110  and the outlet  112 , each providing access to the internal cavity from the base surface of the heatsink. With reference again to  FIG. 1 , the inlet  110  makes a turn before reaching the internal cavity. Similarly, at the outlet end, the outlet  112  makes a turn before it exits at the base surface. The fins  114 ,  116  are positioned at the respective turn. 
         [0021]    The body  102  has a shape such that the heatsink will be substantially flat when assembled (e.g., after the lid is attached). Particularly, the flat body has an edge  200  that in this example is facing the same direction as the inlet and outlet. On the edge, the heatsink has one or more tabs  202  (here, seven tabs). The tabs can be used for positioning, such as to position the heatsink itself or a component attached to it (e.g., by way of a clip or spring). 
         [0022]      FIG. 3  shows an example of the body  102  and the lid  104  from  FIG. 1  being assembled to form the heatsink. The lid is currently at an angle relative to the body, and will be placed flat against the body in the assembly process. Particularly, the lid has an edge  300  that corresponds to an edge  302  on the body, so as to allow the internal cavity to be formed and to be leak-resistant for the coolant. 
         [0023]      FIG. 4  shows an example of a heatsink  400  having components  402 ,  404  attached by springs  406 . Here, each of the springs is in form of a clip that holds two components, one on each side of the heatsink. Tabs can be used for positioning of the springs. For example, tabs  202 A and  202 B here help position the spring  406  so as to resist displacement of the corresponding component(s) held by that spring. For simplicity, the components are here schematically shown. That is, pins, wiring or other connections have been omitted for clarity. 
         [0024]      FIG. 5  shows an assembly  500  of three heatsinks  502  connected to manifolds  504 A-B. Each heatsink is attached so as to provide fluid connection between its inlet and one of the manifolds, and between its outlet and another of the manifolds. The manifolds have respective openings  506 A-B to their respective hollow interiors. For example, coolant can be introduced into the manifold  504 A so as to provide respective parallel coolant flows through the heatsinks  502 , before exiting the manifold  504 B through the opening  506 B. The assembly  500  can be the only unit that is being cooled by a particular circulation of coolant, or the assembly can be one of multiple components or assemblies served by the coolant stream in its circulation. 
         [0025]      FIG. 6  shows an example cross section  600  of the heatsink from  FIG. 1  after assembly. The body  102  and the lid  104  are here attached to each other so that the internal cavity is formed. The pins and half-pins are inside the internal cavity. Particularly, the complete pins  108 B-D, as well as the half-pins  108 A and  108 E, are here visible. Similarly, fins  602 A-D (on the lid in this example) are here visible in cross section. For example, the fins  602 A-D can form the column  118 A or B ( FIG. 1 ). The fins  118 A-E are here oppositely oriented than the fins  602 A-D. Particularly, they are here oriented in opposite directions. Also, the amount of overlap between, on the one hand, the fins  118 A-E, and on the other hand, the fins  602 A-D can be chosen in the process of designing the parts of the heatsink. For example, there is here a full overlap between the fins  118 A-E and  602 A-D. 
         [0026]    The fins  118 A-E and  602 A-D can have any suitable shape. In some implementations, the fins take the shape of pins extending from the respective body and lid. For example, the pins can include complete pins with an oval profile and half-pins that are corresponding half-ovals. The pin shape can depend on the flow condition. For example, a diamond shape or a round shape can work for a very low flow rate situation. 
         [0027]    The fins  602 A-D are offset with regard to the fins  118 A-E. For example, the fins  602 A-D may here be positioned deeper (in the viewing direction) than the fins  108 A-E. This can provide an advantageous flow pattern for the coolant in the internal cavity. For example, a significant amount of turbulent flow can be achieved, which helps provide good thermal transfer from the fins (i.e., from the components attached to the heatsink) into the coolant. On the contrary, the fins  114 ,  116  ( FIG. 1 ) can help avoid turbulent flow near the inlet and outlet. For example, having the flow in these regions be laminar rather than turbulent can help avoid an undesirable pressure drop in the coolant. 
         [0028]      FIG. 7  shows an example of a process  700  for manufacturing a heatsink. At  702 , the respective parts of the device are designed. For example, one can define the shapes of the body and lid shown in  FIG. 1 , so that they will fit within an intended installation space, will physically accommodate the intended components that need cooling, and so that the heat-removing capacity of the heatsink is adequate for the intended use. 
         [0029]    At  704 , a number of fins (e.g., pins) are allocated between the designed parts. The pins can be arranged in respective arrays on the individual pieces. In some implementations, the pins can be allocated so that a column of pins on one of the pieces has N number of pins, and so that a corresponding column on another piece has the functional equivalent of N pins. For example, the other piece can have N−1 complete pins and two half-pins positioned at the ends of the column. This can allow a more equal heat flow from the respective pieces of the heatsink, for example when components are mounted on each side thereof. The design of the shapes will take into account any requirements of the manufacturing process. For example, when heatsink pieces are to be cast, each of the pins  108 ,  118  ( FIG. 1 ) can be provided with a draft so that the cast piece can be removed from the mold. 
         [0030]    At  706 , molds for the respective parts can be created. For example, the molds can comprise the negative shapes corresponding to the body and lid shown in  FIG. 1 . The molds can be made from any suitable material, including, but not limited to, sand. 
         [0031]    The molds can then be installed in a suitable manufacturing environment, such as in a factory. The process of casting pieces using the created molds can then be performed as many times as required, provided that molds may need refurbishing or replacement after a certain amount of use. At  708 , a suitable metal can be liquefied. Any metal or alloy thereof suitable for casting can be used, including, but not limited to, aluminum. At  710 , the liquefied metal is placed into the molds, for example by a gravity-feed process. The molds are allowed to cool at  712 , which can involve passive cooling or actively controlling the temperature as it drops. The cast pieces are removed from the respective molds at  714 , and finished at  716  as necessary to ensure a good fit. 
         [0032]    At  718 , the pieces can be assembled into a heatsink so as to form the internal cavity having the designed groups of pins. Any suitable attachment technique can be used, including, but not limited to, welding or brazing the pieces or applying an adhesive. One advantage of welding or brazing is that the two pieces become one, thermally. As a result, the final heatsink can be very balanced in terms of thermal mass on each side even if its two halves are very different sizes. 
         [0033]    In the above example, the process  700  is directed toward manufacturing the heatsink by casting. This can provide some advantage, for example, that one can obtain essentially any desired separation between the respective fins in the internal cavity. By contrast, if the only fins in the internal cavity were those on either of the individual pieces, with no fins on the opposite piece, then the fin separation would be limited by the manufacturing process. 
         [0034]    In other implementations, another manufacturing technique than casting can be used. For example, the individual pieces (e.g., the body and lid of  FIG. 1 ) can be machined from any suitable material, including, but not limited to, aluminum. 
         [0035]      FIG. 8  shows another example of a heatsink  800  that includes a body  802  and a lid  804 . The body has a hollow portion  806  that has a number of fins  808 . The fins are arranged in a regular pattern, here in rows. Similar to the example in  FIG. 1 , the body  802  here also has an inlet  810  and an outlet  812 , each of which has a corresponding fin  814  or  816 . 
         [0036]    The lid  804  has fins  818  that are configured in accordance with the fins  808  of the body  802 . Similar to the fins of the body, the fins of the lid are arranged in a regular pattern, here in rows. The fins  818  are staggered so as to fit among the fins  808 . For example, a particular one of the fins  818  is configured to fit between the fins  808 A and  808 B when the heatsink is assembled. Another one of the fins  818 , in turn, is configured to fit between the fins  808 B and  808 C when the heatsink is assembled. The fins  808  and  818  are designed so that some space exists between them when assembled, thereby providing a passage for a coolant. 
         [0037]    A number of implementations have been described as examples. Nevertheless, other implementations are covered by the following claims.