Heat sink system and assembly   

CROSS-REFERENCE TO RELATED APPLICATIONS

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 “\'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 “\'247 Application”). The entire disclosures of the \'824 and \'247 Applications are incorporated herein by reference in their entirety.

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.

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.

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.

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.

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.

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

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:

FIG. 1 illustrates an example of a heat sink system in accordance with one embodiment;

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;

FIG. 3 depicts an example embodiment of a heat sink system in accordance with another embodiment;

FIG. 4 depicts a top view of another embodiment of a heat sink system;

FIG. 5 illustrates a top view of one embodiment of the heat sink shown in FIG. 4;

FIG. 6 depicts a top view of an example embodiment of a heat sink system in accordance with another embodiment;

FIG. 7 illustrates a perspective view of a heat sink system in accordance with another embodiment;

FIG. 8 provides a detailed view of a transition seal of the heat sink system shown in FIG. 7 in accordance with one embodiment;

FIG. 9 depicts example leading edge designs for a heat sink fin;

FIG. 10 depicts example embodiments of various fin arrangements;

FIG. 11 illustrates one embodiment of a straddle mount fin support system;

FIG. 12 is an example embodiment of a first fin arrangement;

FIG. 13 is another example embodiment of a second fin arrangement; and

FIG. 14 is another example embodiment of a third fin arrangement.

DETAILED DESCRIPTION

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.

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).

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.

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 104having 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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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).

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

In another example embodiment, as illustrated in FIG. 14, the arrangement 1400 includes the fins 1402a that are of a longer length and curved and fins 1402b that are of a shorter length and straight. The fins 1402a 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 1402a 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 1402b may be curved in an opposite, second direction toward the line A-A and may be referred to as outlet fins.

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 1402a 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.

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.

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.