Heat Sink Assembly

A heat sink assembly includes plural thermally conductive hair fins configured to be thermally coupled with a component to be cooled. The hair fins are elongated along a first direction and separated from each other by gaps along different second and third directions. The hair fins are configured to receive heat from the component to be cooled and to transfer the heat to cooling air disposed between the hair fins in order to cool the component.

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Description
FIELD

Embodiments of the subject matter disclosed herein relate to heat sinks, or components that assist in cooling other components.

BACKGROUND

Powered systems include components that generate heat. For example, some vehicles include electrical devices that generate heat during operation of the vehicles. These devices can include insulated gate bipolar transistors (IGBTs), rectifiers, or other solid state devices that can generate a significant amount of heat. Other heat-generating components, such as dynamic brakes or the like, also can generate significant amounts of heat.

In order to cool these components and allow the continued safe operation of the powered systems, heat sinks may be used to draw the heat away from the components and thereby cool the components. Some heat sinks include elongated planar fins oriented in parallel with each other. These fins draw the heat from another component and dissipate the heat into the surrounding atmosphere through the external surface areas of the fins.

One significant problem with some known heat sinks is the weight of the heat sinks. The heat sink weight can be a significant portion of the total weight of some powered systems. As one example, the cooling system in a vehicle, such as a locomotive or other type of vehicle, of which the heat sinks are a large part, can constitute a significant portion of the weight of the locomotive, such as half of the total weight of the locomotive. The large amount of heat sink weight can significantly reduce the efficiency of operation of the powered systems.

BRIEF DESCRIPTION

In one embodiment, a heat sink assembly includes plural thermally conductive hair fins configured to be thermally coupled with a component to be cooled. The hair fins are elongated along a first direction extending away from the component and separated from each other by gaps along different second and third directions that are orthogonal to the first direction. The hair fins have external dimensions that are longer along the first direction than each of the second and third directions. The hair fins are arranged in an array that includes plural rows of the hair fins, with each row having a respective plurality of the hair fins that are spaced apart from one another in the second direction, and the rows being spaced apart from one another in the third direction. The hair fins are configured to receive heat from the component to be cooled and to transfer the heat to cooling air disposed between the hair fins and flowing between the hair fins in the second and third directions, in order to cool the component. Each of the hair fins has a length along the first direction of at least fifty-five millimeters and a cross-sectional area, defined by a plane of the second and third directions, of no more than 0.0009 square millimeters, and the heat sink assembly has a fin density of the hair fins of at least seventy-seven of the hair fins per square centimeter within an area of the heat sink assembly that includes the hair fins. Optionally, the length may be at least two millimeters and no more than fifty-five millimeters.

In one embodiment, a heat sink assembly includes a housing having opposing side walls and plural thermally conductive hair fins disposed in a grid between the side walls of the housing. The hair fins are configured to be thermally coupled with a component to be cooled. The hair fins are elongated along a first direction and separated from each other by gaps along different second and third directions. The hair fins are configured to receive heat from the component to be cooled and to transfer the heat to cooling air disposed between the hair fins in order to cool the component.

In one example, the first direction extends away from the component, and the second and third directions are orthogonal to one another and to the first direction. The hair fins can have external dimensions that are longer along the first direction than each of the second and third directions. The hair fins can be arranged in the grid as an array that includes plural rows of the hair fins, with each row having a respective plurality of the hair fins that are spaced apart from one another in the second direction. The rows can be spaced apart from one another in the third direction.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter described herein will be better understood from reading the following description of non-limiting embodiments, with reference to the attached drawings, wherein below:

FIG. 1 illustrates one example of a plate type heat sink assembly;

FIG. 2 illustrates a hair fin type heat sink assembly according to one embodiment of the inventive subject matter;

FIG. 3 illustrates another view of the hair fin type heat sink assembly shown in FIG. 2;

FIG. 4 also illustrates the hair fin type heat sink assembly shown in FIG. 2;

FIG. 5 illustrates a hair fin shown in FIGS. 3 and 4 according to one embodiment;

FIG. 6 illustrates the hair fins shown in FIGS. 3 and 4 with no air flow directed between or across the hair fins;

FIG. 7 illustrates the hair fins shown in FIG. 6 with air flowing in a first direction; and

FIG. 8 illustrates the hair fins shown in FIG. 6 with air flowing in an opposite second direction.

 DETAILED DESCRIPTION

One or more embodiments of the inventive subject matter described herein provide heat sink assemblies having lightweight hairs to replace current plate type heat sinks. This hair fin type heat sink assembly has potential to significantly reduce or eliminate cooling air flow requirements, as well as significantly reduce the weight and space needed for the heat sink assemblies of powered systems. The hair fin type heat sink assemblies have higher surface-to-volume ratios when compared to the plate type heat sinks, which can increase the heat transfer coefficient of the hair fin type heat sink assemblies by two or more orders of magnitude over the plate type heat sink assemblies. Moreover, the hair fin type heat sink assemblies can reduce the weight of the heat sink assemblies (e.g., by 50% or more) and/or cooling air flow requirements significantly (e.g., 70% to 100% less air flow through the hair fins) when compared to plate type heat sink assemblies.

FIG. 1 illustrates one example of a plate type heat sink assembly 100. The plate type heat sink assembly 100 includes an outer housing 102 in which several elongated and planar plate type fins 104 are oriented in parallel with each other. The housing 102 is coupled with a component 106 to be cooled by the heat sink assembly 100. The component 106 can represent an electrical device such as an IGBT, a rectifier, a dynamic brake system, or the like, that generates heat. The plate type fins 104 are planar bodies in that each of the fins 104 has much a much larger external dimension in each of two orthogonal directions 108, 110 than in a third orthogonal direction 112. For example, each of the plate type fins 104 shown in FIG. 1 can have an external dimension along the direction 108 (e.g., between opposite front and back ends of the fin 104) that is 215 millimeters, an external direction along the direction 110 (e.g., between opposite top and bottom edges of the fin 104) that is fifty-five millimeters, and an external direction along the direction 112 (e.g., between the opposite planar sides of the fin 104) that is only two millimeters.

Heat generated in or by the component 106 is transferred to the plate type fins 104. Cooling air flows into the housing 102 through inlets 114 of the housing 102. This air may be supplied from a fan, blower, etc. The cooling air flows within the gaps between the plate type fins 104 and exits the housing 102 through an outlet 116 of the housing 102. The cooling air draws heat in the plate type fins 104 from the component 106 and carries at least some of this heat out of the heat sink assembly 100 through the outlet 116.

A powered system, such as a vehicle (e.g., a locomotive, automobile, mining vehicle, etc.), may include several heat sinks. The plate type fin heat sink assemblies 100 can be significant contributors to the overall weight of the powered system, and can require a significant flow of cooling air into the housing 102 in order to draw the heat off of the plate type fins 104.

FIGS. 2 through 4 illustrate a hair fin type heat sink assembly 200 according to one embodiment of the inventive subject matter. The heat sink assembly 200 includes a housing 202 formed from parallel side walls 204, 206 disposed on opposite sides of an array or field 208 of hair fins 300 (shown in FIGS. 3 and 4). The hair fins 300 are arranged in a grid or regular array in the field 208. For example, the hair fins 300 that neighbor or are next to each other may be equidistantly spaced and separated from each other by gaps along the direction 108 and along the direction 112. Alternatively, the distance between neighboring hair fins 300 may be larger in one direction 108 or 112 than the distance between neighboring hair fins 300 in the other direction 112 or 108.

FIG. 5 illustrates one of the hair fins 300 shown in FIGS. 3 and 4 according to one embodiment. The hair fins 300 are elongated along one direction by a much greater distance than the dimensions of the hair fins 300 along other orthogonal directions. For example, the hair fins 300 may have an outer dimension 500 that is longer along the direction 110 than outer dimensions 502, 504 of the hair fins 300 along either of the directions 108, 112. In one embodiment, the hair fins 300 may have a small aspect ratio indicative of this elongation, such as a ratio of the width to the height of the hair fin 300 of less than 0.001, less than 0.0008, less than 0.0006, or another value. One example of the hair fins 300 has an outer dimension along the direction 110 of at least fifty-five millimeters and an outer dimension along each of the directions 108, 112 of no greater than 0.03 millimeters to provide an aspect ratio of 0.000545 and a cross-sectional area of 0.0009 mm2. Alternatively, the hair fins 300 may have other dimensions. For example, the outer dimension along each of the directions 108, 112 may be no greater than 0.1 micron or no greater than one micron.

The small cross-sectional area of the hair fins 300 in a plane defined by the directions 108, 112 allows for the hair fins 300 to be fairly close together in a dense arrangement. The density of the fins 300 in the plane defined by the directions 108, 112 may be significantly large, such as at least 500 to no more than 2,000 fins 300 per square inch (or at least 77 fins 300 per square centimeter to no more than 310 fins 300 per square centimeter). This large density of hair fins 300 allows the hair fin type heat sink assembly 200 to have a large heat flux density (e.g., the amount of heat that is drawn out of the air flowing between the fins 300), such as a heat flux density of at least 500 watts per square inch (or at least 77.5 watts per square centimeter), at least 700 watts per square inch (or at least 108 watts per square centimeter), or up to 1,000 watts per square inch (or up to 155 watts per square centimeter).

The hair fins 300 may be formed from one or more thermally conductive materials, such as aluminum or another metal or metal alloy. In one embodiment, the hair fins 300 are formed from a flexible material that allows the hair fins 300 to individually flex or bend with the flow of air across the field of hair fins 300. The flexibility of the hair fins 300 is shown in FIGS. 6 through 8. In FIG. 6, no air flow is directed between the hair fins 300. As a result, the hair fins 300 are substantially or completely vertically oriented. In FIG. 7, air flows between the hair fins 300 from a left-to-right direction in the perspective of FIG. 7. In FIG. 8, air flows between the hair fins 300 from a right-to-left direction in the perspective of FIG. 8. As shown in FIGS. 7 and 8, the hair fins 300 slightly change shape from a straight or linear shape to a bent shape. The flow of air against the hair fins 300 changes the shape of the hair fins 300 due to the flexible nature of the hair fins 300.

As shown in FIG. 5, the hair fins 300 may have a square cross-sectional shape in a plane that is parallel or defined by the directions 108, 112. Alternatively, the hair fins 300 may have a circular or other cross-sectional shape. The different cross-sectional shapes may depend on the pressure and/or rate of cooling air flowing through the field 208 of hair fins 300.

In operation, the heat sink assembly 200 is coupled with the component 106 to be cooled. The hair fins 300 are thermally coupled with the component 106, such as by directly coupling the hair fins 300 with the component 106 or by coupling the hair fins 300 with a thermally conductive plate 302 that is coupled to the component 106. Cooling air is directed along a direction oriented between or parallel to the opposing side walls 204, 206 of the housing 202. This cooling air passes through and between the hair fins 300 along an inlet direction shown in FIG. 2. Due to the gaps between the hair fins 300 along multiple different directions, the cooling air is able to flow between the hair fins 300 in a direction that is opposite of the direction 112, in the direction 108, and in the direction that is opposite of the direction 108. This can allow for increased or more rapid cooling of the heat transferred from the component 106 to the hair fins 300 (relative to the plate type fins). The air may exit out of the heat sink assembly 200 along a side of the field 208 that is opposite of the inlet. The side walls 204, 206 can constrain flow of the cooling air through the field 208 to remain between the hair fins 300 from one end 210 of the field 208 to the opposite end 212 of the field 208.

The hair fins 300 have been found to significantly increase heat transfer from the component 106 to the cooling air relative to plate type fins. The hair fins 300 provide considerably more surface area through which heat is transferred to the cooling air when compared to the plate type fins. For example, the hair fins 300 may provide upward of fifty or more times surface area than the plate type fins.

In one example, the component 106 generated heat in the amount of two watts, and the hair fins 300 were found to cool a plate disposed between the hair fins 300 and the component 106 to an average temperature of ninety-nine degrees Celsius, while the heat sink assembly 100 having the plate type fins only cooled the plate to an average temperature of 140 degrees Celsius.

The hair fins 300 also can provide significantly higher heat transfer coefficients than the plate type fins. For example, the hair fins 300 may provide a heat transfer coefficient of 11,000 or more.

Additionally, because of the many different paths that the cooling air may take through the field 208 of hair fins 300, the amount, flow rate, or mass flow rate of the cooling air passing through the field 208 may be less than that for the plate style fins, while still cooling the component 106 as much or more than the plate style fins extending over the same distance along the direction 112. For example, 70% or less of the air flow used to cool the component 106 using the plate style fins may be used to cool the same component 106 by the same amount or more when using the hair fins 300.

A method for providing the heat sink assembly 200 may include obtaining several of the hair fins 300 and coupling the hair fins 300 to the component 106 to be cooled. The hair fins 300 may be coupled with a plate that is then coupled with the component 106, or may be directly coupled with the component 106. The hair fins 300 are separated from each other to allow cooling air to flow between the hair fins 300 along plural different directions.

In one embodiment, a heat sink assembly includes plural thermally conductive hair fins configured to be thermally coupled with a component to be cooled. The hair fins are elongated along a first direction extending away from the component and separated from each other by gaps along different second and third directions that are orthogonal to the first direction. The hair fins have external dimensions that are longer along the first direction than each of the second and third directions. The hair fins are arranged in an array that includes plural rows of the hair fins, with each row having a respective plurality of the hair fins that are spaced apart from one another in the second direction, and the rows being spaced apart from one another in the third direction. The hair fins are configured to receive heat from the component to be cooled and to transfer the heat to cooling air disposed between the hair fins and flowing between the hair fins in the second and third directions, in order to cool the component. Each of the hair fins has a length along the first direction of at least fifty-five millimeters and a cross-sectional area, defined by a plane of the second and third directions, of no more than 0.0009 square millimeters, and the heat sink assembly has a fin density of the hair fins of at least seventy-seven of the hair fins per square centimeter within an area of the heat sink assembly that includes the hair fins.

In one example, the hair fins have square cross-sectional shapes in a plane defined by the second and third directions.

In one example, the assembly also includes a housing having opposing side walls on opposite sides of the hair fins.

In one example, the hair fins are arranged in a grid with the hair fins being equidistant from each other in the grid along the second and third directions.

In one example, the hair fins are separated from each other by first distances along the second direction and different, second distances along the third direction.

In one example, each of the hair fins has an aspect ratio of less than 0.001.

In one example, the first direction is oriented perpendicularly to at least one of the component or to a thermally conductive plate to which the hair fins are attached, the plate being configured for attachment to the component.

In one embodiment, a heat sink assembly includes plural thermally conductive hair fins configured to be thermally coupled with a component to be cooled. The hair fins are separated from each other by gaps along different directions. The hair fins are configured to receive heat from the component to be cooled and to transfer the heat to cooling air disposed between the hair fins in order to cool the component.

In one example, the different directions of the gaps, by which the hair fins are separated from each other, are orthogonal, and the hair fins are configured to receive the heat from the component to be cooled and to transfer the heat to the cooling air that flows along the different orthogonal directions between the hair fins.

In one example, the hair fins are elongated along a direction that is orthogonal to the different orthogonal directions in which the cooling air flows.

In one example, the hair fins have square cross-sectional shapes in a plane defined by the different orthogonal directions.

In one example, the assembly also includes a housing having opposing side walls on opposite sides of the hair fins.

In one example, the hair fins are arranged in a grid with the hair fins being equidistant from each other in the grid along the different orthogonal directions.

In one example, each of the hair fins has an aspect ratio of less than 0.001.

In one embodiment, a heat sink assembly includes a housing having opposing side walls and plural thermally conductive hair fins disposed in a grid between the side walls of the housing. The hair fins are configured to be thermally coupled with a component to be cooled. The hair fins are elongated along a first direction and separated from each other by gaps along different second and third directions. The hair fins are configured to receive heat from the component to be cooled and to transfer the heat to cooling air disposed between the hair fins in order to cool the component.

In one example, hair fins are separated from each other by the gaps such that the cooling air flows between the hair fins in both the second and third directions.

In one example, the hair fins have external dimensions that are longer along the first direction than each of the second and third directions.

In one example, the hair fins are arranged in the grid with the hair fins being equidistant from each other in the grid along the second and third directions.

In one example, each of the hair fins has an aspect ratio of less than 0.001.

In one example, the first direction extends away from the component, and the second and third directions are orthogonal to one another and to the first direction. The hair fins can have external dimensions that are longer along the first direction than each of the second and third directions. The hair fins can be arranged in the grid as an array that includes plural rows of the hair fins, with each row having a respective plurality of the hair fins that are spaced apart from one another in the second direction. The rows can be spaced apart from one another in the third direction.

The foregoing description of certain embodiments of the inventive subject matter will be better understood when read in conjunction with the appended drawings. The above description is illustrative and not restrictive. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the inventive subject matter without departing from its scope. While the dimensions and types of materials described herein are intended to define the parameters of the inventive subject matter, they are by no means limiting and are example embodiments. Other embodiments may be apparent to one of ordinary skill in the art upon reviewing the above description. The scope of the inventive subject matter should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. Further, the limitations of the following claims are not written in means-plus-function format and are not intended to be interpreted based on 35 U.S.C. § 112(f), unless and until such claim limitations expressly use the phrase “means for” followed by a statement of function void of further structure. And, as used herein, an element or step recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural of said elements or steps, unless such exclusion is explicitly stated. Furthermore, references to “one embodiment” of the inventive subject matter are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Moreover, unless explicitly stated to the contrary, embodiments “comprising,” “including,” or “having” an element or a plurality of elements having a particular property may include additional such elements not having that property.

This written description uses examples to disclose several embodiments of the inventive subject matter and also to enable a person of ordinary skill in the art to practice the embodiments of the inventive subject matter, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the inventive subject matter is defined by the claims, and may include other examples that occur to those of ordinary skill in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

Claims

1. A heat sink assembly comprising:

plural thermally conductive hair fins configured to be thermally coupled with a component to be cooled, the hair fins being elongated along a first direction extending away from the component and separated from each other by gaps along different second and third directions that are orthogonal to the first direction, wherein the hair fins have external dimensions that are longer along the first direction than each of the second and third directions,
wherein the hair fins are arranged in an array that includes plural rows of the hair fins, each row having a respective plurality of the hair fins that are spaced apart from one another in the second direction, and the rows being spaced apart from one another in the third direction,
wherein the hair fins are configured to receive heat from the component to be cooled and to transfer the heat to cooling air disposed between the hair fins and flowing between the hair fins in the second and third directions, in order to cool the component, and
wherein each of the hair fins has a length along the first direction of at least two millimeters and no more than fifty-five millimeters and a cross-sectional area, defined by a plane of the second and third directions, of no more than 0.0009 square millimeters, and the heat sink assembly has a fin density of the hair fins of at least seventy-seven of the hair fins per square centimeter within an area of the heat sink assembly that includes the hair fins.

2. The heat sink assembly of claim 1, wherein the hair fins have square cross-sectional shapes in a plane defined by the second and third directions.

3. The heat sink assembly of claim 1, further comprising a housing having opposing side walls on opposite sides of the hair fins.

4. The heat sink assembly of claim 1, wherein the hair fins are arranged in a grid with the hair fins being equidistant from each other in the grid along the second and third directions.

5. The heat sink assembly of claim 1, wherein the hair fins are separated from each other by first distances along the second direction and different, second distances along the third direction.

6. The heat sink assembly of claim 1, wherein each of the hair fins has an aspect ratio of less than 0.001.

7. The heat sink assembly of claim 1, wherein the first direction is oriented perpendicularly to at least one of the component or to a thermally conductive plate to which the hair fins are attached, the plate being configured for attachment to the component.

8. A heat sink assembly comprising:

plural thermally conductive hair fins configured to be thermally coupled with a component to be cooled, the hair fins separated from each other by gaps along different directions, wherein the hair fins are configured to receive heat from the component to be cooled and to transfer the heat to cooling air disposed between the hair fins in order to cool the component.

9. The heat sink assembly of claim 8, wherein the different directions of the gaps, by which the hair fins are separated from each other, are orthogonal, and wherein the hair fins are configured to receive the heat from the component to be cooled and to transfer the heat to the cooling air that flows along the different orthogonal directions between the hair fins.

10. The heat sink assembly of claim 9, wherein the hair fins are elongated along a direction that is orthogonal to the different orthogonal directions in which the cooling air flows.

11. The heat sink assembly of claim 9, wherein the hair fins have square cross-sectional shapes in a plane defined by the different orthogonal directions.

12. The heat sink assembly of claim 9, further comprising a housing having opposing side walls on opposite sides of the hair fins.

13. The heat sink assembly of claim 9, wherein the hair fins are arranged in a grid with the hair fins being equidistant from each other in the grid along the different orthogonal directions.

14. The heat sink assembly of claim 9, wherein each of the hair fins has an aspect ratio of less than 0.001.

15. A heat sink assembly comprising:

a housing having opposing side walls; and
plural thermally conductive hair fins disposed in a grid between the side walls of the housing, the hair fins configured to be thermally coupled with a component to be cooled, the hair fins being elongated along a first direction and separated from each other by gaps along different second and third directions, wherein the hair fins are configured to receive heat from the component to be cooled and to transfer the heat to cooling air disposed between the hair fins in order to cool the component.

16. The heat sink assembly of claim 15, wherein the hair fins are separated from each other by the gaps such that the cooling air flows between the hair fins in both the second and third directions.

17. The heat sink assembly of claim 15, wherein the hair fins have external dimensions that are longer along the first direction than each of the second and third directions.

18. The heat sink assembly of claim 15, wherein the hair fins are arranged in the grid with the hair fins being equidistant from each other in the grid along the second and third directions.

19. The heat sink assembly of claim 15, wherein each of the hair fins has an aspect ratio of less than 0.001.

20. The heat sink assembly of claim 15, wherein:

the first direction extends away from the component, and the second and third directions are orthogonal to one another and to the first direction;
the hair fins have external dimensions that are longer along the first direction than each of the second and third directions; and
the hair fins are arranged in the grid as an array that includes plural rows of the hair fins, each row having a respective plurality of the hair fins that are spaced apart from one another in the second direction, and the rows being spaced apart from one another in the third direction.
Patent History
Publication number: 20180058773
Type: Application
Filed: Aug 31, 2016
Publication Date: Mar 1, 2018
Inventors: Subramani Adhiachari (Bangalore), Jayesh Jain (Bangalore)
Application Number: 15/252,213
Classifications
International Classification: F28F 3/02 (20060101); F28D 21/00 (20060101);