Patent Publication Number: US-2023154821-A1

Title: Heat sink with turbulent structures

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application of, and claims priority to, U.S. patent application Ser. No. 17/318,900, titled “HEAT SINK WITH TURBULENT STRUCTURES,” filed on May 12, 2021, which is a continuation application of, and claims priority to, U.S. patent application Ser. No. 16/843,536, now U.S. Pat. No. 11,039,550, titled “HEAT SINK WITH TURBULENT STRUCTURES,” filed on Apr. 8, 2020. The disclosures of the foregoing applications are incorporated herein by reference in their entirety for all purposes. 
    
    
     TECHNICAL FIELD 
     This specification relates generally to providing cooling to electronic equipment. 
     BACKGROUND 
     Electronic devices generate heat through power consumption. Excessive heat generation without sufficient cooling can lead to damage and failure of electronic devices. Electronic devices may be cooled by cooling systems such as heat sinks. Heat sinks are passive heat exchangers that transfer heat from electronic devices to a fluid medium. 
     SUMMARY 
     Heat sinks can be used to cool electronic devices, e.g., processors, memories, network devices, and other heat generating devices. In computing systems, heat sinks can be used to cool central processing units (CPUs), graphics processing units (GPUs), tensor processing units (TPU), chipsets, and random access memory (RAM) modules, and other electronic devices. 
     A heat sink is a passive heat exchanger that can transfer heat generated by an electronic device to a lower temperature fluid medium, such as air or a liquid coolant. The fluid medium removes and disperses heat from the electronic device. A heat sink can be used to lower or maintain the temperature of the electronic device, preventing the electronic device from overheating. 
     The amount of heat that can be removed by a heat sink is dependent on various factors, to include the surface area of the heat sink, the fluid volume and velocity through the heat sink, and the direction of fluid flow through the heat sink. Heat sink performance can be improved by increasing the amount of heat that the heat sink removes from the electronic device. Heat sink performance can also be improved by increasing the rate of heat removal from the electronic device. 
     In general, one innovative aspect of the subject matter described in this specification can be embodied in a heat sink including: a base defining a first side having a base planar surface and a second side opposite the first side; and a plurality of planar fins extending from the base planar surface in parallel disposition relative to each other, each planar fin of the plurality of planar fins comprising: a bottom fin edge coupled to the base planar surface and running parallel a longitudinal axis of the planar fin, a top fin edge that is opposite the bottom fin edge and running parallel the longitudinal axis of the planar fin, a leading fin edge extending from the bottom fin edge to the top fin edge, a trailing fin edge opposite the leading fin edge and extending from the bottom fin edge to the top fin edge, a fin body extending from the bottom fin edge to the top fin edge and having a first side defining a first planar surface and second side opposite the first side defining a second planar surface; and a first set of turbulent structures extending from the first planar surface, each turbulent structure in the first set of turbulent structures defining a longitudinal axis and having a first edge that is parallel to the longitudinal axis and connected to the first planar surface and a second edge opposite the first edged and in free space, the second edge defining a periphery that varies in distance from the first edge along the length of the longitudinal axis; and wherein the periphery of each second edge is further shaped such that turbulent flow of a fluid is induced in the fluid flowing over the second edge at at least a predefined flow rate. 
     Another innovative aspect of the subject matter described in this specification can be embodied in a planar fin comprising a bottom fin edge coupled to the base planar surface and running parallel a longitudinal axis of the planar fin; a top fin edge that is opposite the bottom fin edge and running parallel the longitudinal axis of the planar fin; a leading fin edge extending from the bottom fin edge to the top fin edge; a trailing fin edge opposite the leading fin edge and extending from the bottom fin edge to the top fin edge; a fin body extending from the bottom fin edge to the top fin edge and having a first side defining a first planar surface and second side opposite the first side defining a second planar surface; and a first set of turbulent structures extending from the first planar surface, each turbulent structure in the first set of turbulent structures defining a longitudinal axis and having a first edge that is parallel to the longitudinal axis and connected to the first planar surface and a second edge opposite the first edged and in free space, the second edge defining a periphery that varies in distance from the first edge along the length of the longitudinal axis; and wherein the periphery of each second edge is further shaped such that turbulent flow of a fluid is induced in the flow flowing over the second edge at at least a predefined flow rate. 
     Another innovative aspect of the subject matter described in this specification can be embodied in a heat sink including heat sink comprising: a base defining a first side having a base planar surface and a second side opposite the first side; and a plurality of planar fins extending from the base planar surface in parallel disposition relative to each other, each planar fin of the plurality of planar fins comprising: a bottom fin edge coupled to the base planar surface and running parallel a longitudinal axis of the planar fin; a top fin edge that is opposite the bottom fin edge and running parallel the longitudinal axis of the planar fin; a leading fin edge extending from the bottom fin edge to the top fin edge; a trailing fin edge opposite the leading fin edge and extending from the bottom fin edge to the top fin edge; fin body extending from the bottom fin edge to the top fin edge and having a first side defining a first planar surface and second side opposite the first side defining a second planar surface; and means for inducing turbulent flow extending from the first planar surface and that induce turbulent flow of a fluid flowing over the means at at least a predefined flow rate. 
     The details of one or more embodiments of the subject matter of this specification are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages of the subject matter will become apparent from the description, the drawings, and the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a diagram of an example heat sink with planar fins that include turbulent structures. 
         FIG.  2    is top view of the planar fins with turbulent structures. 
         FIG.  3    is a side view of a turbulent structure. 
         FIG.  4    is a perspective view of a turbulent structure with a terminal nub. 
         FIG.  5    is a side view of another turbulent structure. 
     
    
    
     Like reference numbers and designations in the various drawings indicate like elements. 
     DETAILED DESCRIPTION 
     Heatsink performance is improved when turbulent flow occurs between the fins when the fluid flows at the predefined rate. To induce turbulent flow, the planar fins of the heat sink include a set of turbulent structures. The turbulent structures extend from a first planar surface of the fin, e.g., a first side of the fin. Each turbulent structure in the first set of turbulent structures defines a longitudinal axis and has a first edge that is parallel to the longitudinal axis and connected to the first planar surface. Each turbulent structure also has a second edge opposite the first edge and in free space. The second edge defines a periphery that varies in distance from the first edge along the length of the longitudinal axis. For example, the periphery can be saw tooth shaped, straight tooth shaped, or even curved. The periphery of each second edge is further shaped such that turbulent flow of a fluid is induced in the fluid flowing over the second edge at at least a predefined flow rate. 
     Turbulent structures can also be attached to the other side of the heatsink fin and offset from the structures on the first side of the heatsink fin. In this configuration, the turbulent structures extend into the space between heatsinks from both heatsink surfaces. With higher turbulence, the heat sink realizes a higher heat transfer coefficient h that would otherwise be realized with smooth fins. This leads to better convection cooling capabilities. Thus, the principle of this design is to add turbulence enhancement features on the heatsink fins to increase heat transfer coefficient. 
     These features and additional features are described in more detail below. 
       FIG.  1    is a diagram of an example heat sink  100  with planar fins  110  that include turbulent structures  132 . The heat sink  100  includes a base  102  defining a first side  104  having a base planar surface, and a second side  106  opposite the first side  104 . A set of planar fins  110  (e.g.,  110 - 1  . . . N) extend from the base planar surface  106  in parallel disposition relative to each other. Each planar fin  110  includes a bottom fin edge  112  coupled to the base planar surface  106  and running parallel to a longitudinal axis  111  of the planar fin  110 . Each planar fin  110  also is defined by a top fin edge  114  that is opposite the bottom fin edge  112  and running parallel to the longitudinal axis  111  of the planar fin, and is further defined by a leading fin edge  116  extending from the bottom fin  112  edge to the top fin edge  114 , and a trailing fin edge  118  opposite the leading fin edge  114  and extending from the bottom fin edge  112  to the top fin edge  114 . 
       FIG.  2    is top view of the planar fins  110  with turbulent structures  132 . Each fin  110  defines a fin body  120  extending from the bottom fin edge  112  to the top fin edge  114  and having a first side  122  defining a first planar surface and second side  124  opposite the first side defining a second planar surface. To avoid congestion in the drawings, like elements for all fins  110  are not labeled. 
     In some implementations, except for exterior fins  110 - 1  and  110 -N, each planar fin  110  includes a first set of turbulent structures  132 - 1  extending from the first planar surface  122 , and a second set of turbulent structures  132 - 2  extending from the second planar surface  134 . Exterior fin  110 - 1 , however, includes only a first set of turbulent structures  132 - 1  on the first planar surface  122 . Conversely, exterior fin  110 -N includes only a second set of turbulent structures  132 - 2  on the second planar surface  124 . In other implementations, exterior fins  110 - 1  and  110 -N have turbulent structures  132  on both of their respective first planar surface  122  and second planar surface  134 . 
     The turbulent structures  132  are uniformly spaced apart, and each respective set  132 - 1  and  132 - 2  are offset from each other so as to not overly reduce airflow that would otherwise result if the sets  132 - 1  and  132 - 2  were not offset. 
       FIG.  3    is a side perspective of a turbulent structure  132 . Each turbulent structure  132  defines longitudinal axis  140  and having a first edge  142  that is parallel to the longitudinal axis  140 . The first edge  142  is connected to the planar surface  122  or  124 . In some implementations, the turbulent structures  132  are connected at an acute angle A, as shown in  FIG.  2   . The turbulent structure  132  includes a second edge  144  opposite the first edge  142 . The second edge, as shown in  FIG.  2   , is in free space such that air may flow over the second edge  142 . The second edge  144  defines a periphery  145  (a second edge of which is shown in phantom and offset in  FIG.  2   ) that varies in distance from the first edge  142  along the length of the longitudinal axis  140 . The periphery  145  of each second edge  144  is further shaped such that turbulent flow of a fluid is induced in the fluid flowing over the second edge  144  at at least a predefined flow rate, e.g., at a flow rate induced by a fan  101 . As shown in  FIG.  3   , the periphery  145  varies linearly in distance from the edge  142  from a maximum distance of H to a minimum distance of h, with the relative maximum and minimum spaced apart by a distance d. The values of A, H, h and d can be varied to achieve different heat transfer coefficients. Such heat transfer coefficients can be measured empirically, for example. 
     The triangular shape of  FIG.  3    is but one example of a periphery that can be used. For example, as shown in  FIG.  5   , a turbulent structure  202  with a curved periphery pattern  204  can be used. Other periphery patterns can also be used, such as a saw-tooth pattern, a straight tooth pattern, or still other patterns. 
     In some implementations, the second edge  144  has a uniform cross section. In other implementations, however, each second edge  144  may include terminal nubs  146  to further increase turbulent flow. As shown in  FIG.  4   , the terminal nub  146  is pyramidal in shape; however, a variety of other shapes can be used. 
     While this specification contains many specific implementation details, these should not be construed as limitations on the scope of what may be claimed, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in this specification in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination. 
     Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Moreover, the separation of various system modules and components in the embodiments described above should not be understood as requiring such separation in all embodiments, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products. 
     Particular embodiments of the subject matter have been described. Other embodiments are within the scope of the following claims. For example, the actions recited in the claims can be performed in a different order and still achieve desirable results. As one example, the processes depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results. In some cases, multitasking and parallel processing may be advantageous.