Abstract:
A heat sink system with reduced airborne debris clogging, for cooling power electronics, the heat sink system including a heat sink having a plurality of fins, a housing configured to direct air flow around the side, top, and/or bottom of the heat sink and then through the fins of the heat sink at a back of the heat sink, and an inlet airway passage formed between a wall of the housing and said side, top, and/or bottom of the finned heat sink to allow air to pass within the housing, wherein said side, top, and/or bottom of the heat sink comprises at least one of said plurality of fins disposed directly in contact with the inlet airway passage.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of and claims priority benefit from U.S. patent application Ser. No. 12/340,824 (filed on 22Dec. 2008, and referred to herein as the “&#39;824 Application”), which is a continuation of and claims priority benefit from U.S. patent application Ser. No. 11/291,247 (filed on 1 Dec. 2005, and referred to herein as the “&#39;247 Application”). The entire disclosures of the &#39;824 and &#39;247 Applications are incorporated herein by reference in their entirety. 
     
    
     BACKGROUND 
       [0002]    One or more embodiments of the inventive subject matter described herein relate to transportation vehicles that use relatively high power electronics that may require cooling systems and, more particularly, to a heat sink assembly for reducing airway blockage in the heat sink assembly. 
         [0003]    Vehicles such as locomotives and related transportation vehicles can be equipped with power electronics having cooling systems that use finned heat sinks to aid in heat dissipation. These heat sinks are cooled by forced air. Previous heat sink designs have been used which employ typical fin arrangements with uniform spacing between the fins of the heat sinks. The cooling capability of the heat sink can depend on the number of fins, the spacing of the fins, the shape of the fins, and the size of the fins. An example heat sink that is currently used in locomotives is one developed by Aavid Thermalloy. 
         [0004]    In some situations, airflow is directed to flow through the heat sink. Some known designs of heat sinks are susceptible to plugging with airborne debris such as diesel fumes, dust, dirt, and the like. When plugged, the effectiveness of the heat sink can be dramatically reduced, resulting in poorer cooling of the power electronics that rely on the heat sink for cooling and potentially increased failure rates of the electronics due to excessive temperatures the electronics may experience as a result of the effectiveness of the heat sink being reduced. 
       BRIEF DESCRIPTION 
       [0005]    One or more embodiments of the presently described inventive subject matter relate to a system, assembly, and method for cooling electronics with reduced airborne debris clogging in the heat sink. In one embodiment, a heat sink system includes a heat sink having a plurality of fins and a housing configured to direct air flow around a side, top, and/or bottom of the heat sink and through the fins of the heat sink at a back of the heat sink. The heat sink system also includes an inlet airway passage formed between a wall of the housing and the side, top, and/or bottom of the finned heat sink to allow air to pass within the housing. In one embodiment, the side, top, and/or bottom of the heat sink include at least one of the fins disposed directly in contact with the inlet airway passage. 
         [0006]    In another embodiment, in a cooling system having a heat sink system with air passing through an inlet airway passage to reach a plurality of fins on a heat sink, the heat sink system includes a transition seal between the heat sink and the inlet airway passage. The heat sink system may also include a slot proximate the inlet airway passage to receive an outer fin of the heat sink. The outer fin is of a thickness to contact the inner edges of the slot. At least one of the fins can be in thermal connection with the inlet airway passage. 
         [0007]    In another embodiment, a heat sink assembly includes a base element defining two dimensions of the heat sink assembly and a plurality of fins attached to and extending from the base element. The heat sink assembly also includes an inlet airway passage through which air travels to reach the plurality of fins, and a transition seal between the heat sink and the inlet airflow passage. The heat sink assembly also includes a slot (such as a ribbed slot) that is located proximate the inlet airflow passage to receive an outer fin of the heat sink, where the outer fin is of a thickness to contact inner edges of the slot. At least one of the fins is in thermal connection with the inlet airflow passage. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    A more particular description of the inventive subject matter briefly described above will be rendered by reference to specific embodiments thereof that are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the inventive subject matter and are not therefore to be considered to be limiting of its scope, the inventive subject matter will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
           [0009]      FIG. 1  illustrates an example of a heat sink system in accordance with one embodiment; 
           [0010]      FIG. 2  depicts an example embodiment of a cross-section of the heat sink shown in  FIG. 1  along line  2 - 2  in  FIG. 1 ; 
           [0011]      FIG. 3  depicts an example embodiment of a heat sink system in accordance with another embodiment; 
           [0012]      FIG. 4  depicts a top view of another embodiment of a heat sink system; 
           [0013]      FIG. 5  illustrates a top view of one embodiment of the heat sink shown in  FIG. 4 ; 
           [0014]      FIG. 6  depicts a top view of an example embodiment of a heat sink system in accordance with another embodiment; 
           [0015]      FIG. 7  illustrates a perspective view of a heat sink system in accordance with another embodiment; 
           [0016]      FIG. 8  provides a detailed view of a transition seal of the heat sink system shown in  FIG. 7  in accordance with one embodiment; 
           [0017]      FIG. 9  depicts example leading edge designs for a heat sink fin; 
           [0018]      FIG. 10  depicts example embodiments of various fin arrangements; 
           [0019]      FIG. 11  illustrates one embodiment of a straddle mount fin support system; 
           [0020]      FIG. 12  is an example embodiment of a first fin arrangement; 
           [0021]      FIG. 13  is another example embodiment of a second fin arrangement; and 
           [0022]      FIG. 14  is another example embodiment of a third fin arrangement. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    With reference to the figures, example embodiments of the inventive subject matter will now be described. However, it should be noted that, though the presently described inventive subject matter describes various inventions or improvements that may be used in a heat sink system, these inventions or improvements may be used individually in a single application or various combinations, including all versions at once, may be used together. Toward this end, the example embodiments described herein should not be viewed as individual inventions since one or more of the embodiments described herein can be used collectively with one or more other embodiments as well. 
         [0024]      FIG. 1  illustrates an example of a heat sink system  100  in accordance with one embodiment. The heat sink system  100  includes a housing  102  with a heat sink  104  contained in the housing  102 . The housing  102  contains and channels the airflow  106  through the heat sink  104  to cool the airflow  106 . The heat sink  104  can be held in position by placement of the heat sink  104  between two or more solid divider walls  108  that oppose each other. The divider walls  108  also separate the heat sink  104  from inlet airflow passages  110  (also referred to herein as airflow passages  110  or inlet paths  110 ) disposed on opposite sides of the heat sink  104 . As shown in  FIG. 1 , the divider walls  108  define at least part of the inlet airflow passages  110  (e.g., by forming one side of each of the inlet airflow passages  110 ). 
         [0025]    The heat sink  104  has fins  112  through which the airflow  106  is directed. As the airflow  106  travels through the housing  102  and through the inlet airflow passageways  110 , the airflow  106  experiences bends  114  in the housing  102  and the inlet airflow passageways  110 . As the airflow  106  experiences the bends  114 , heavier debris particles in the airflow  106  may be forced to the outside of the radius of the bends  114 , and may impinge upon a center  116  of a heat sink face  118  of the heat sink  104  where the two inlet airflow passageways  110  converge. This phenomenon has been further verified through debris ingestion testing of heat sinks  104 . Once debris clogging is initiated in the center  116  of the heat sink  104 , plugging of the heat sink  104  can occur and can then proceed to increase, or grow, across the face  118  of the heat sink  104  toward the divider walls  108 . 
         [0026]    With continued reference to  FIG. 1 ,  FIG. 2  depicts an example embodiment of a cross-section of the heat sink  104  along line  2 - 2  in  FIG. 1 . The heat sink  104  includes the finned heat sink  104 having a center-bypass area  120 . The fins  112  are laterally spaced apart by the same or approximately the same separation distance  200  with at least two of the fins  112  laterally spaced apart by a greater separation distance  202  than the other fins  112 . The separation of the fins  112  by the greater separation distance  202  creates the bypass area  120  (also referred to herein as a bypass channel) in the heat sink  104 . In the illustrated embodiment, the bypass area  120  provides an open channel through or between the center  116  of the heat sink fins  112  which allows for airborne debris to pass through the heat sink  104  (e.g., through the bypass area  120 ) without depositing on the inlet face  118  of the heat sink  104 . 
         [0027]    In one embodiment, the bypass area  120  can be formed by removing one or more fins  112  from the heat sink  114 . To offset such a removal of the heat sink fins  112 , the overall size of the heat sink  104  may be modified in overall width, fin height, length, and/or a number of fins  112  to achieve equivalent thermal performance when compared to a heat sink that does not include the bypass area  120 . This can be achieved with constant spacing between the fins  112  and a bigger spacing in the bypass area  120 , and/or by having a gradually increased spacing between the fins  112  toward the center  116  of the heat sink  104 . While the bypass area  120  is shown as being disposed in the center  116  of the face  118  of the heat sink  104 , the bypass area  120  may not be located in the center  116  of the face  118 , but may located where a higher or the highest concentration of debris is expected. 
         [0028]      FIG. 3  depicts an example embodiment of a heat sink system  300  in accordance with another embodiment. The heat sink system  300  includes a housing  302  having housing guide vanes  304  and a finned heat sink  306 . In one embodiment, the heat sink  306  may be similar to the heat sink  104  shown in  FIGS. 1 and 2 . The vanes  304  can include walls disposed in inlet airflow passageways  308  of the housing  302  that can separate at least some of the debris-laden air (“Dirty Airflow” in  FIG. 3 ) of the airflow  106  that is flowing through the inlet airflow passageways  308  from the airflow  106  that does not include debris or includes relatively less debris (“Clean Airflow” in  FIG. 3 ). For example, the vanes  304  are disposed between, and spaced apart from, outer surfaces  310  of the inlet airflow passageways  308  and opposing inner surfaces  312  of the inlet airflow passageways  308 . In the illustrated embodiment, at least part of the inner surfaces  312  includes divider walls  314 , which may be similar to the divider walls  108  (shown in  FIG. 1 ). Also as shown in  FIG. 3 , the vanes  304  may extend from an inlet face  316  of the heat sink  306  that receives the airflow  106  and partially along the inlet air passageways  308 . The vanes  304  may have shapes that are at least partially curved to follow or approximately follow the curvature of the inlet airflow passageways  308 . 
         [0029]    Including the vanes  304  in the housing  302  may further enhance the effectiveness of the heat sink  306  having a bypass area that is similar to the bypass area  120  (shown in  FIG. 1 ) described above. For example, the heat sink  104  may be included in the housing  302  as the heat sink  306  with the bypass area  120  at least partially disposed between the vanes  304  such that the vanes  304  direct at least some of the Dirty Airflow into the bypass area  120 . For example, the vanes  304  may be used to more precisely control the amount and specific portion of the airflow  106  that is diverted or directed through the bypass area  120  (e.g., the Dirty Airflow) while allowing or directing the other airflow  106  (e.g., the Clean Airflow) between the fins of the heat sink  104 . The vanes  304  may direct the heavier particles in the airflow  106  to the opening of the bypass area  120  so as to delay and/or avoid the initiation of plugging of the spaces between the fins of the heat sink  306 . Although only two vanes  304  are illustrated, a larger number of vanes  304  may be included in the housing  302 . 
         [0030]    As shown in  FIG. 3 , the heat sink  306  may be mounted between two divider walls  314  which act to locate the heat sink  306  so as to channel the airflow  106  through the heat sink  306 . Additional concepts of packaging the heat sink  306  may be employed to increase the volume of the heat sink  306  without increasing the overall size and/or weight of the heat sink  306 . Increasing the volume of the heat sink  306  may allow for one or more fins  112  of the heat sink  306  to be removed or moved from the heat sink  306 , which in turn can allow for increased separation distances between the fins  112  without an associated loss in effective heat transfer area of the heat sink  306 . 
         [0031]      FIG. 4  depicts a top view of another embodiment of a heat sink system  400 . The heat sink system  400  includes a finned heat sink  402  within a housing  404  that does not include the divider walls on opposite sides of the heat sink  402 . For example, the housing  404  may be similar to the housing  302  (shown in  FIG. 3 ) with the divider walls  314  (shown in  FIG. 3 ) of the housing  300  removed. 
         [0032]    As shown in  FIG. 4 , the airflow  106  flows through inlet airflow passageways  406  disposed between the heat sink  402  and the housing  404 . The airflow  106  moves around sides of the heat sink  402 , curves along bends  408  in the housing  404 , and flows into an inlet face  410  of the heat sink  402 . In the illustrated embodiment, the heat sink  402  does not include a bypass channel that is similar to the bypass channel  120  shown in  FIG. 1 . Alternatively, the heat sink  402  may include a bypass channel. 
         [0033]      FIG. 5  illustrates a top view of one embodiment of the heat sink  402  shown in  FIG. 4 . Similar to the heat sink  104  (shown in  FIG. 1 ), the heat sink  402  includes a plurality of fins  500 ,  502  that are laterally spaced apart from each other. The fins  500 ,  502  include interior fins  500  and outside fins  502 , with the outside fins  502  disposed outside of, and on opposite sides of, the interior fins  500 . For example, the outside fins  502  may be located on opposite sides of the heat sink  402 . 
         [0034]    In the illustrated embodiment, the outside heat sink fins  502  may have a larger thickness dimension  504  than a thickness dimension  506  of the interior fins  500 . For example, the outside fins  502  may be made thicker than the interior fins  500  so as to provide additional structural support and/or to improve heat transfer rates of the heat sink system  404 . Increasing the thickness dimension  504  of the outside fins  502  can provide the structural strength that is supplied by the divider walls  314  (shown in  FIG. 3 ) of the heat sink system  300 . For example, with the divider walls  314  not being present in the heat sink system  400 , the outside fins  502  can provide the structural strength to the heat sink  402  that is otherwise provided by the divider walls  314  shown in  FIG. 3 . 
         [0035]    Additionally, and as shown in  FIG. 4 , the outside heat sink fins  502  are disposed along the inlet airflow passageways  406  of the housing  404 . Positioning the outside heat sink fins  502  along the inlet airflow passageways  406  causes the outside heat sink fins  502  to define at least part of the surfaces of the inlet airflow passageways  406 . As airflow  106  flows through the inlet airflow passageways  406 , at least some of the airflow  106  may come into direct contact with the outside fins  502 . The direct contact between the airflow  106  and the outside fins  502  can cause at least some thermal energy (e.g., heat) to be transferred from the airflow  106  to the heat sink  402  before the airflow  106  flows through the heat sink  402 . 
         [0036]      FIG. 6  depicts a top view of an example embodiment of a heat sink system  600  in accordance with another embodiment. The heat sink system  600  includes a finned heat sink  602  having several heat sink fins  604 . The heat sink  602  is disposed within a housing  606 . In contrast to the heat sink systems  300  (shown in  FIG. 3) and 400  (shown in  FIG. 4 ), the heat sink  602  extends across or through inlet airflow passageways  608  of the heat sink system  600 , as shown in  FIG. 6 . For example, the heat sink  602  may laterally extend across the entirety of the interior of the housing  606 . 
         [0037]      FIG. 7  illustrates a perspective view of a heat sink system  700  in accordance with another embodiment.  FIG. 8  provides a detailed view of a transition seal  800  of the heat sink system  700  that is disposed between a heat sink fin  702  of a heat sink  704  of the heat sink system  700  and a housing  706  of the heat sink system  700  in accordance with one embodiment. While the heat sink  700  is shown as including fins  702  across the width of the heat sink  700 , alternatively, one or more of the fins  702  may be removed or otherwise not present to form one or more bypass areas that are similar to the bypass areas  120  (shown in  FIG. 1 ) of the heat sink  104  (shown in  FIG. 1 ). 
         [0038]    The housing  706  of the heat sink system  700  may be similar to the housing  302  (shown in  FIG. 3 ) of the heat sink system  300  (shown in  FIG. 3 ), except that the divider walls  312  (shown in  FIG. 3 ) of the housing  302  may be at least partially removed to form the transition seal  800 . For example, at least a portion of the divider walls  312  may be removed except for a sloped portion  802  (shown in  FIG. 8 ) at an end of the housing  706 . The sloped portion  802  is provided so as to have a transition seal between the heat sink  704  and the housing  706 , including an inlet airflow passage  708  and a weldment  804 . Also, the housing  706  can include a ribbed slot  806  to facilitate the easy location and application of a sealing member  808 , such as a gasket. The sealing member  808  can include a pressure sensitive adhesive on one side. Alternatively, another type of sealing material may be used. 
         [0039]    The heat sink  704  is constructed with one or more outer or outside solid fins  702  that have shapes that are complimentary to the shapes of the sloped portion  802  of the transition seal  800 . For example, the outside fins  702  may have a convex portion with a radius of curvature that matches the radius of curvature of the concave portion in the transition seal  800  that is formed by the sloped portion  802 . The outer fins  702  may have appropriate thicknesses so as to fit into the ribbed slots  806  on opposite sides of the heat sink  704 . The receipt of the outside fins  702  into the ribbed slots  806  may compress the sealing members  808  (e.g., gaskets) that run along the length of the outside fins  702 . The outside fins  702  may act as the divider walls of the housing  700 , such as the outside fins  502  (shown in  FIG. 5 ) of the heat sink system  500  (shown in  FIG. 5 ) act as the divider walls of the heat sink system  500 . For example, the heat sink  704  may replace the divider walls  314 . The engagement between the outside fins  702  and the transition seal  800  may form a seal to the airflow  106  such that the airflow  106  does not flow between the interface between the outside fins  702  and the sloped portion  802 . 
         [0040]    Even though a transition seal and slope portion are disclosed to provide a seal between a heat sink and a base, alternatively, other embodiments are possible to achieve the same connection wherein the heat sink fins  702  are in thermal connection with a base. For example, the fins  702 , having a rectangular shape, may have an end that extends to the weldment  804  of the housing  706 . The fins  702  that may be located in or adjacent to the inlet airflow passageways  708  may also be in thermal connection with the airflow passageways  708 . 
         [0041]    In the illustrated embodiment, a controlled restriction element  810  may be provided at the same end of the housing  706  through which the airflow  106  is received into the inlet airflow passageways  708 . As illustrated in  FIG. 7 , the restriction element  810  is attached to the housing  706 . Alternatively, the restriction element  810  can be part of or connected to the heat sink  704 . This restriction element  810  may be used to control and/or regulate a pressure drop through the heat sink  704  due to increased spacing between two or more of the fins  702  in the heat sink  704 . The restriction elements  810  can increase the pressure drop through or across the heat sink system  700  by reducing cross-sectional sizes of openings  710  through which the airflow  106  is received into the inlet airflow passageways  708 . 
         [0042]    In one embodiment, a plurality of heat sinks, such as up to thirty-six (36), may be used on a vehicle such as a locomotive. The pressure drop across all of the heat sinks may be uniform. Thus, if a new heat sink replaces a current heat sink on the locomotive, the pressure drop across this new heat sink may need to be uniform to the existing pressure drops across the other heat sinks. Toward this end, a restriction element  810  is sized to ensure a uniform pressure drop across the replacement heat sink  704 . By doing this, one heat sink may have a different sized restriction element  810  than another. This allows for ensuring that all future heat sinks are backward compatible with existing heat sinks in a system, such as a locomotive. 
         [0043]    For example, if the heat sink  704  includes one or more bypass areas similar to the bypass area  120  (shown in  FIG. 1 ) of the heat sink  104  (shown in  FIG. 1 ), then the pressure drop of the airflow  106  flowing through the heat sink  704  may be smaller than the pressure drop of the airflow  106  flowing through another heat sink that does not include a bypass area, or that includes a smaller number of bypass areas or smaller separation distances between the fins to form the bypass area. When multiple heat sink systems are arranged in parallel (such that the airflow  106  may flow through a plurality of the heat sink systems in parallel), the pressure drop across each of the heat sink systems may be equal or approximately equal to avoid substantially more airflow  106  flowing through one or more of the heat sink systems relative to other heat sink systems. In a vehicle or system having multiple heat sink systems, including one or more of the heat sink systems  100 ,  300 ,  400 ,  700  (shown in  FIGS. 1 ,  3 ,  4 , and  7 ) having heat sinks with one or more bypass areas  120 , the restriction elements  810  may be included in the heat sink systems to increase the pressure drop across the heat sink systems  100 ,  300 ,  400 ,  700  to be equal, approximately equal, or greater than the pressure drops across one or more other heat sink systems connected in parallel with the heat sink systems  100 ,  300 ,  400 , and/or  700 . For example, if a vehicle is retrofitted with a heat sink having one or more bypass areas  120  while one or more other heat sinks disposed in parallel do not have such bypass areas  120 , the restriction elements  810  may be used to increase the pressure drop across the heat sinks having the bypass areas up to the pressure drops across the other, non-retrofitted heat sinks. 
         [0044]    In addition with respect to the housing  706 , an access port  712  (not visible but having a location or locations identified in  FIG. 7 ) is provided to facilitate inspection of heat sink clogging and/or cleaning of the heat sink  704 . 
         [0045]      FIG. 9  depicts example leading edge designs for a heat sink fin. An improved leading edge design can assist in reducing a rate of plugging of a heat sink, such as one or more of the heat sinks  108 ,  306 ,  402 ,  602 ,  704  (shown in  FIGS. 1 ,  3 ,  4 ,  6 , and  7 ). In one embodiment of a design of a heat sink fin  900 , shown in in  FIG. 9(   a ), a leading edge  902  has a flat surface  904 . 
         [0046]    In another embodiment, a heat sink fin  906  has a leading edge  908  that is shaped with a pointed, beveled edge  910 , as illustrated in  FIG. 9(   b ). Alternatively, a heat sink fin  912  may have a leading edge  914  that includes a rounded-off edge  916 , as illustrated in  FIG. 9(   c ). The leading edges  902 ,  908 ,  914  may be disposed at one or more of the leading edge (e.g., the edge of the fin that contacts the airflow  106  shown in  FIG. 1  as the airflow  106  enters the heat sink having the fin) and/or a trailing edge (e.g., the opposite edge of the fin that contacts the airflow  106  as the airflow  106  exits the heat sink having the fin) of the fins  900 ,  906 ,  912 . In the case of fin designs that are not solid or continuous, such as the segmented or augmented fins disclosed below, one or more of the leading edges  902 ,  908 ,  914  may also be extended to the leading and/or trailing edges of each of a plurality of fin segments of the fins. 
         [0047]    In another embodiment, a surface finish of one or more fins in a heat sink may be altered to reduce a propensity of particles in the airflow  106  (shown in  FIG. 1 ) from sticking to the surface of the fins. To achieve a non-stick fin, the fin may be processed to have a very fine surface finish, and/or coatings may be applied to produce a non-stick surface. Teflon, fluoropolymers, PFA, PTFE, and FEP are some examples of coatings available that may be applied to reduce the propensity of particles in the airflow  106  from sticking to the fins. 
         [0048]      FIG. 10  depicts example embodiments of various fin arrangements. As illustrated, at least four different concepts for the fin arrangements are shown. The concepts depicted include, in  FIG. 10(   a ), an augmented fin  1000  and, in  FIG. 10(   b ), a straight fin  1002 . The augmented fin  1000  has parts  1004  of the fin  1000  that extend into the area where airflow  106  (shown in  FIG. 1)  passes, which in turn may cause turbulence. The area of turbulence can result in debris buildup, or plugging, of a heat sink. 
         [0049]    A configuration of a segmented fin  1006  depicted in  FIG. 10(   c ) includes the fin  1006  divided in a plurality of discrete segments  1008  that are spaced apart from each other. For example, as shown in  FIG. 10(   c ), the segments  1008  may be separated from each other along a length of the fin  1006 . The segmented fin  1006  may provide similar turbulence as the augmented fin  1000  without providing edges or portions of the fin  1006  that stick into the air stream of the airflow  106 . By not having parts of the fin  1006  extending into the airflow  106 , the probability of plugging the heat sink with debris in the airflow  106  may be reduced. 
         [0050]      FIG. 10(   d ) depicts design of a wavy fin  1010  that likewise attempts to increase turbulence and heat transfer while removing leading edges that promote accretion of debris. As shown in  FIG. 10(   d ), the wavy fin  1010  includes an elongated body  1012  having an undulating shape. The body  1012  may be continuous between opposite ends  1014 ,  1016  of the body  1012 . 
         [0051]    In addition to providing enhanced clog resistance, edge treatment of the fins and various fin configurations may be performed or combined with other parameters such as varied fin geometry (e.g., thickness, height, and the like of the fins) and/or fin spacing, to tune and/or reduce the airflow-induced noise generation of the heat sink. For example,  FIG. 11  illustrates one embodiment of a straddle mount fin support system  1100  that may be included in a heat sink. The system  1100  may be used to attach each of a plurality of fins  1102  to a base plate  1104  on a heat sink. As shown in  FIG. 11 , the system  1100  may include grooves  1106  that receive ends  1106  of the fins  1102 . 
         [0052]    Since the fin thickness may be small, the support of the fins  1102  may be provided by bending portions  1110  of the fins  1102 . Different fins  1102  may be bent in opposite directions (e.g., as shown with respect to the fins “A” and “B”) and then supporting the fins  1102  on the heat sink base  1104 . For example, the fins  1102  that are bent in different directions may be coupled together to form a single fin when the ends  1108  of the fins A and B are placed into neighboring grooves  1106  of the system  1100 . Alternatively, thicker fins (such as the fins  112  shown in  FIG. 2 ) may be used and/or more space may be provided between the fins and/or, the fins may be made thicker, such as illustrated in  FIG. 2 , so as to have a better heat transfer rate and to be able to support without bending portions of the fins in opposite directions. 
         [0053]      FIGS. 12 ,  13 , and  14  are example embodiments of fin arrangements  1200 ,  1300 ,  1400  of varying lengths. The fin arrangements  1200 ,  1300 ,  1400  include fins  1202 ,  1302 ,  1402  that may be included in one or more of the heat sinks described herein, such as the heat sink  602  shown in  FIG. 6 . The fin arrangements  1200 ,  1300 ,  1400  are described herein with reference to the heat sink system  600  shown in  FIG. 6 , but alternatively may be used with one or more other heat sink systems described herein. 
         [0054]    In one embodiment,  FIGS. 12 ,  13 , and  14  show one side of the fins in a heat sink, such as the fins on one side of a line through a heat sink taken along line A-A of  FIG. 6 , wherein the fin arrangement  1200 ,  1300 , and/or  1400  used in the heat sink is different than the fin arrangement shown in  FIG. 6 . For example, the areas designated as “inlet” in  FIGS. 12 ,  13 , and  14  may include the fins  1202 ,  1302 ,  1402  that are in the heat sink  602  and that are located within one side of the inlet airflow passageway  608 . As illustrated, where the fins  1202 ,  1302 ,  1402  are in the inlet airflow passageway  608 , the fins  1202 ,  1302 ,  1402  in this area can be of varied length to direct the path of the airflow  106 . Alternatively, other varied lengths of the fins  1202 ,  1302 , and/or  1402  may be utilized to achieve a similar result in another embodiment. 
         [0055]    As illustrated in  FIG. 12 , the fins  1202  in the inlet airflow passageway  608  are longer toward the left outer edge of the heat sink  602  (in the view shown in  FIG. 12 ) and then reduce in length the closer that the fins  1202  are to other heat sink fins  1202  that are used as an outlet  1204  for the airflow  106 . For example, the airflow  106  may flow into the heat sink  602  between the fins  1202  having varying lengths that decrease as the fins  1202  are farther from the housing  606  that holds the heat sink  602 . These fins  1202  may be referred to as “inlet fins.” When the airflow  106  passes ends of the inlet fins  1202 , the airflow  106  may turn as shown in  FIG. 12  due at least in part to the varying lengths of the inlet fins  1202 . 
         [0056]    Other fins  1202  disposed between the inlet fins  1202  and the line A-A in  FIGS. 6 and 12  may conversely increase in length from the inlet fins  1202  toward the line A-A. For example, the length of the fins  1202  may increase as the fins  1202  are farther from inlet fins  1202 . The varying length inlet fins  1202  and outlet fins  1202  can cause the airflow  106  to flow through the inlet fins  1202 , turn toward the outlet fins  1202 , and flow through the outlet fins  1202  and out of the heat sink  602  at or near the same end of the housing  600  that the airflow  106  is initially received into the heat sink  602 . Alternatively, instead of the fins  1202  having varying lengths, the inlet fins  1202  and/or outlet fins  1202  may have the same or approximately the same length and be cascaded (e.g., staggered in position so that the ends of the fins  1202  are arranged as shown in  FIG. 12 ) to turn the airflow  106  toward the outlet fins  1202 . 
         [0057]    In another example embodiment, shown in  FIG. 13 , the inlet fins  1202  of the embodiment shown in  FIG. 12  may be removed such that the airflow  106  moves through an inlet airflow passageway  1304  that is similar to the inlet airflow passageway  308  (shown in  FIG. 3 ). The fins  1302  may be arranged similar to the outlet fins  1202  shown in  FIG. 12  such that the inlet airflow passageway  1304  and/or the arrangement  1300  of the outlet fins  1302  directs (e.g., turns) the airflow  106  to the outlet fins  1302 . 
         [0058]    In another example embodiment, as illustrated in  FIG. 14 , the arrangement  1400  includes the fins  1402   a  that are of a longer length and curved and fins  1402   b  that are of a shorter length and straight. The fins  1402   a  may be disposed in and/or define an inlet airflow passageway (e.g., similar to the inlet airflow passageway defined by the inlet fins  1202  of  FIG. 12 ). Some of the curved fins  1402   a  may be curved in a first direction toward the line A-A shown in  FIGS. 6 and 14  and may be referred to as inlet fins. Other curved fins  1402   b  may be curved in an opposite, second direction toward the line A-A and may be referred to as outlet fins. 
         [0059]    The fins  1402  may define turning vanes that turn the airflow  106  from the inlet fins  1402  toward the outlet fins  1402  instead of having the turning vanes being part of the housing, such as in the embodiment shown in  FIG. 3 . As shown in  FIG. 14 , not every fin  1402  may be curved to define a turning vane. For example, as illustrated in  FIG. 14 , every other fin  1402  may be a curved fin  1402   a  that has a vane as part of the fin  1402 . Alternatively, all of the fins  1402  or a different number or arrangement of the fins  1402  may be curved and/or straight. The vanes defined by the fins  1402  may be of varied lengths and can be used to improve turning efficiency and flow distribution of the airflow  106  through the heat sink. Though vanes are illustrated on the inlet fins  1402 , in another example embodiment the inlet fins  1402  may not include the vanes. 
         [0060]    When fins of varying length are used and/or curved fins are used, as discussed above, the housing for the heat sink may no longer be required. For example, the housing  602  shown in  FIG. 6  may not be used as the fins  1202 ,  1204 ,  1302 , and/or  1402  used in the heat sink  602  may direct and control the movement of the airflow  106  in the heat sink  602 . Toward this end, one less element is required within the cooling system, which results in a cost savings. 
         [0061]    While one or more embodiments of the inventive subject matter has been described in what is presently considered to be a preferred embodiment, many variations and modifications may become apparent to one of ordinary skill in the art. Accordingly, it is intended that the inventive subject matter not be limited to the specific illustrative embodiment, but be interpreted within the full spirit and scope of the appended claims.