HEAT SINK WITH HEAT BUS AND FIN STRUCTURE

Abstract

A heat sink to remove heat from a processor within a chassis to air moving through a fin structure on the heat sink. An embodiment of the heat sink comprises a heat bus engaging the processor to conduct heat from the processor to a fin structure having interconnected, repeating cellular air channels. A U-shaped heat bus comprises a base and first and second legs extending therefrom connected to opposite sides of the fin structure. An embodiment of the heat bus has a solid conductive core to conductively transfer heat from the processor through the base and the first and second legs to sides of the fin structure. Alternately, an embodiment of the heat bus has a hollow core containing a fluid to evaporatively transfer heat from the processor through the base and the first and second legs to sides of the fin structure.

Description

BACKGROUND

1. Field of the Invention

The present invention relates to heat sinks to remove heat from heat-generating electronic devices, such as computer processors.

2. Background of the Related Art

Computer systems often rely on heat sinks positioned on heat-generating electronic components, such as processors, to maintain performance of the component by removing heat and thereby maintaining a favorable operating temperature. Heat sinks generally conduct heat generated by a component to fins where the heat is transferred into an air flow across the surface area of the fins. Heat sinks are available with several types of air-cooled fins including pin fins, straight fins, folded fins, flared fins and extruded fins. With increasing processor power densities, more heat is generated by processors disposed within the limited space of the computer chassis. It is important that the heat sink is sufficient to maintain the performance of the processor and still fit with the space and form factor of the chassis.

Heat sink fin structures with larger surface areas for convective heat transfer are able to dissipate more heat to surrounding air, but merely increasing the size and number of fins yields diminishing returns for the space consumed. Dense electronic configurations and increasing processor power densities demand greater heat-dissipation capability to maintain processor performance while controlling heat sink cost and weight.

BRIEF SUMMARY

One embodiment of the present invention provides a heat sink comprising a fin structure having a plurality of repeating, interconnected fin cells that allow the movement of air through the fin cells, wherein the fin structure further includes a first side and a second side. The heat sink further comprises a heat bus that thermally engages a heat-generating electronic component and the first side and the second side of the fin structure, wherein the heat bus facilitates the transfer of heat from the heat-generating electronic component to the first and second sides of the fin structure, and wherein the fin structure has lateral conductive pathways to conduct heat from the first and second sides of the fin structure toward a central region of the fin structure.

Another embodiment of the invention provides a heat sink comprising a fin structure having a plurality of interconnected repeating cellular air channels that allow the movement of air there through to remove heat from the fin structure. The heat sink further comprises a heat bus having a first portion conductively connected to a bottom of the fin structure, a second portion conductively connected to a first side of the fin structure and a third portion conductively connected to a second side of the fin structure, wherein the heat bus facilitates the removal of heat from the first portion of the heat bus to the first side and second side of the fin structure for dissipation to air moving through the air channels of the fin structure.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a perspective view of an embodiment of a heat sink of the present invention comprising a heat bus connected to a honeycomb fin structure having a plurality of interconnected, repeating cellular air channels.

FIG. 2 is a section end view of an embodiment of a heat sink of the present invention comprising a honeycomb fin structure coupled to a U-shaped heat bus.

FIG. 3 is a section end view of a second embodiment of a heat sink of the present invention comprising a honeycomb fin structure coupled to a U-shaped heat bus having a portion that conforms to the side of the fin structure.

FIG. 4 is a perspective view of a third embodiment of a heat sink of the present invention comprising a honeycomb fin structure coupled to a U-shaped heat bus having a plurality of branches to enhance heat distribution to the fin structure.

FIG. 5A is a perspective view of a fourth embodiment of a heat sink of the present invention comprising a honeycomb fin structure coupled to a U-shaped heat bus having a broad profile to enhance heat distribution to the fin structure.

FIG. 5B is a perspective view of a modified fourth embodiment of the heat sink of FIG. 5A comprising a honeycomb fin structure coupled to a U-shaped heat bus that extends the length of the honeycomb fin structure to further enhance heat distribution to the fin structure.

FIG. 6 is a section end view of an embodiment of a heat sink of the present invention comprising a honeycomb fin structure coupled to a U-shaped heat bus that comprises a U-shaped heat pipe.

FIG. 7A is a section end view of another embodiment of a heat sink of the present invention comprising a honeycomb fin structure coupled to a heat bus that substantially surrounds the fin structure and comprises two heat pipes.

FIG. 7B is a perspective view of an embodiment of a heat sink comprising a honeycomb fin structure coupled to a heat bus that substantially surrounds the fin structure.

DETAILED DESCRIPTION

Embodiments of the heat sink of the present invention comprise a heat bus and a fin structure to remove heat from a heat-generating electronic component, such as a processor. An embodiment of the heat sink of the present invention comprises a fin structure for dissipating heat to air flowing through air channels within the fin structure. The fin structure comprises repeating interconnected cellular air channels that may be circular or have a plurality of sides and shapes. Examples of such repeating interconnected cellular air channels include hexagonal (honeycomb) air channels, pentagonal air channels, quadrilateral (e.g., trapezoidal, rectangular or square) air channels and triangular air channels, or combinations of two or more of these. The fin structure generally comprises a bottom intermediate, a first side and a second side.

An embodiment of the heat sink of the present invention further comprises a heat bus to move heat from one or more hot locations to one or more cold locations, the heat bus having a first portion at a hot location and one or more second portions conductively connected to a fin structure at cold locations. The one or more second portions may, for example, be connected to the fin structure at the bottom, at the first side and/or at the second side of the fin structure.

The heat bus may, in one embodiment, comprise two or more branches to provide more than one heat conduit through which heat may move from the base to the fin structure. In a heat bus with two or more branches, heat may move from a base of the heat bus that engages the processor to a right branch of the heat bus that is connected to a right portion of the bottom of the fin structure and to a right portion of the fin structure adjacent to the right portion of the bottom of the fin structure, and heat may also move from the base of the heat bus to a left branch of the heat bus that is connected to a left portion of the bottom of the fin structure and to a left portion of the fin structure adjacent to the left portion of the bottom of the fin structure. Multiple branches of the heat bus provide increased heat transfer capacity to move heat from the base through the heat bus to the fin structure for dissipation to air flowing through air channels within the fin structure.

In one embodiment, the heat bus is further connected to a top of the fin structure. For example, an embodiment of a heat sink may have a heat bus comprising a right leg conductively connected to a right portion of the bottom of the fin structure, to a right portion of the fin structure adjacent to the right portion of the bottom of the fin structure, and to a right portion of the top of the fin structure adjacent the right portion of the fin structure. The heat bus may further comprise a left leg connected to a left portion of the bottom of the fin structure, to a left portion of the fin structure adjacent to the left portion of the bottom of the fin structure, and to a left portion of the top of the fin structure adjacent the left portion of the fin structure. In this configuration, the heat bus provides increased capacity to move heat from the base to substantially the entire periphery of the fin structure, vertically from the base and the top of the heat bus to a central region of the fin structure and laterally from the right portion and the left portion to the central region of the fin structure for more uniform dissipation of heat to air flowing through the fin structure.

A “heat bus,” as that term is used herein, is a heat conduit to transfer heat from a hot location at a base to at least one cold location at a portion of a fin structure remote from the base. A heat bus may comprise a spreader bar, which may be an elongate and/or branched heat conduit having a generally solid core to conduct heat from a hot location to at least one cold location, and the spreader bar may comprise a highly thermally conductive material such as copper. A heat bus may comprise two or more legs or branches to enhance heat distribution to a fin structure, and the legs or branches of the heat bus may comprise two or more legs or branches disposed, along with a base, in a U-shaped configuration to increase heat conduction from a hot location at the base to one or more cold locations on the fin structure.

A heat bus may comprise a heat pipe, a conductive member having a hollow sealed core containing a fluid to transfer heat from a hot location to one or more cold locations by conduction, through the solid portion, and through cyclic evaporation and condensation of the fluid sealed within the hollow core. A wick member may be disposed within the hollow core to promote movement of the fluid along the hollow core of the heat pipe. The wick, which may, for example, comprise a few layers of a fine gauze, may be affixed to the inside surface of the core, and capillary forces within the wick will move condensate condensed from vapor at the “condenser” portion(s) at the cold location(s) of the heat bus to the “evaporator” portion(s) at the hot location(s) of the heat bus. If the evaporator portions(s) of the heat bus are lower in elevation than the condenser portion(s), gravitational forces assist the capillary forces within the wick. A wickless heat pipe relies on gravitational forces alone to move condensed fluid within the core from the condenser portion(s) to the evaporator portion(s) of the heat bus.

The improved distribution of heat from the base to the fin structure improves cooling performance of the heat sink. The heat bus may also decrease the weight of the heat sink for a given heat dissipation capacity and may thereby reduce the overall cost of the heat sink and the computer in which the heat sink is installed.

FIG. 1 is a perspective view of an embodiment of a heat sink 10 of the present invention comprising a honeycomb fin structure 12 having an air inlet end 24 and an air outlet end 25 and a plurality of interconnected, repeating cellular air channels 15 for convection heat transfer from the fin structure 12 to air drawn through the air channels 15 by an air mover (not shown) that may be disposed in a computer chassis (not shown) in which the heat sink 10 is also disposed. The heat sink 10 further comprises a U-shaped heat bus 14 having a first leg 21 along a first side of the fin structure 12, a second leg 23 (partially shown) along a second side of the fin structure 12 and a base portion 26 there between. In the embodiment of FIG. 1, the base 26 is as wide as the width 27 of the fin structure 12. The base 26 of the U-shaped heat bus 14 of the heat sink 10 is adapted to thermally engage a processor (not shown) along a first face 28 to conduct heat from the processor to the fin structure 12 for convective heat transfer to air moving through the air channels 15. The heat bus 14 conductively engages a bottom portion of the fin structure 12 along a second face 29 of the base portion 26 and is connected to the sides of the fin structure 12 at the first leg 21 and the second leg 23. It will be understood that the interconnected, repeating cellular air channels 15 within the fin structure 10 provide for conduction of heat from the base 26 of the heat bus 14 and from the first leg 21 and second leg 23 of the heat bus 14 generally inwardly towards the central region 50 of the fin structure 10. As used herein, the central region of the fin structure is generally defined by the intersection of a vertical axis of symmetry 49 and a horizontal axis of symmetry 60 of the fin structure 10.

FIG. 2 is a section end view of the embodiment of the heat sink 10 of FIG. 1 with the heat sink secured over a processor 20. FIG. 2 illustrates the honeycomb fin structure 12 coupled to a U-shaped heat bus 14 having a first leg 21 and a second leg 23 disposed along opposing sides 16 of the fin structure 12 of the heat sink 10. A thermal interface material 22 is disposed intermediate the processor 20 and the first face 28 of the base 26 of the heat sink 10 to conform to the first face 28 of the base 26 of the heat sink 10 and to a face 69 of the processor 20 and promote heat transfer from the processor 20 to the heat sink 10. The fin structure 10 of FIG. 2 comprises repeating and interconnected hexagonal cells 13 that form elongate air channels 15 extending from and into the sheet. Other embodiments of the heat sink 10 may have fin structures 12 having alternative repeating and interconnected cells 13, such as pentagonal cells, quadrilateral cells, trapezoidal cells, triangular cells or circular cells, and the structure of the heat sink 10 of the present invention is limited only by the claims that are appended hereto.

The fin structure 12 of the embodiment of the heat sink 10 of FIG. 2 comprises a plurality of landings 19 disposed along the sides 16 of the fin structure 12. The first leg 21 of the U-shaped heat bus 14 of FIG. 2 is connected to the fin structure 12 at landings 19 by connections 18 and the second leg 23 of the heat bus 14 is connected to the fin structure 12 by connections 18 at landings 19. Embodiments of the heat sink 10 of the present invention may include connections 18 that are, for example, welded, soldered, or brazed to enhance conductive heat transfer from the heat bus 14 across the connections 18 to the fin structure 12.

FIG. 3 is a section end view of alternate second embodiment of a heat sink 10 of the present invention, where the heat sink is secured over the processor 20. The heat sink 10 comprises a honeycomb fin structure 12 coupled to a U-shaped heat bus 14 having a first leg 21 having a first side 15 and a second side 11 that generally conforms to the side 16 of the fin structure 12 disposed adjacent to the first leg 21. The U-shaped heat bus 14 further comprises a second leg 23 having a first side 15 and a second side 11 that generally conforms to the side 16 of the fin structure 12 adjacent to the second leg 23. The second sides 11 of the first leg 21 and the second leg 23 of the embodiment of the U-shaped heat bus 14 of FIG. 3 are in generally uninterrupted contact with the sides 16 of the fin structure 12, and perhaps generally continuously connected to the sides 16, to enhance conductive heat transfer from the first leg 21 and the second leg 23 of the U-shaped heat bus 14 to the fin structure 12.

FIG. 4 is a perspective view of a third embodiment of a heat sink 10 of the present invention comprising a honeycomb fin structure 12 coupled to a U-shaped heat bus 14 having a base 26, a plurality of first legs 21 and a plurality of second legs 23 (partially shown) along the opposing side of the fin structure. The first legs 21 and the second legs 23 are connected to the landings 19 on the sides 16 of the fin structure 12 by connections 18 to further enhance distribution of heat from the processor (not shown), through the base 26 and the first legs 21 and second legs 23 of the heat bus 14 to the fin structure 12. The first legs 21 are illustrated in FIG. 4 as being parallel and generally equally spaced along the length of the fin structure 12 between the inlet end 24 and the outlet end 25 of the air channels 15 therein.

FIG. 5A is a perspective view of a fourth embodiment of a heat sink 10 of the present invention comprising a honeycomb fin structure 12 coupled to a U-shaped heat bus 14 having a base 26, a first leg 21 having a width 48 and a second leg 23 (partially shown) extending from the base 26 and connected to landings 19 on the fin structure 12 by connections 18. The first leg 21 and the second leg 23 of the heat bus 14 shown in FIG. 5A have a broad profile or width 48 to further enhance distribution of heat from the processor (not shown), through the base 26 and the first leg 21 and second leg 23 of the heat bus 14 to the fin structure 12. It will be understood that other embodiments of the heat sink 10 may comprise a heat bus 14 having a first leg and a second leg that are as wide (dimension 48) as the fin structure 10 is long from the inlet end 24 to the outlet end 25.

FIG. 5B is a perspective view of a modified fourth embodiment of the heat sink 10 of FIG. 5A comprising a honeycomb fin structure 12 coupled to a U-shaped heat bus 14 having a first leg 21 and a second leg 23. Both legs 21, 23 have a length 47 that co-extends the entire length (from the inlet end 24 to the outlet end 25) of the honeycomb fin structure 12 to which the heat bus 14 is coupled further enhance heat distribution to the fin structure 12.

FIG. 6 is a section end view of a fifth embodiment of a heat sink 10 of the present invention comprising a honeycomb fin structure 12 coupled to a U-shaped heat bus 14 that comprises a first L-shaped heat pipe 32 and a second L-shaped heat pipe 33. The first and second L-shaped heat pipes 32, 33 comprise hollow cores 39 containing a fluid (not shown) such as water that moves heat from hot locations 40 to cold locations 41 through the evaporation-condensation cycle. The first L-shaped heat pipe 32 comprises a first portion 34 disposed within the base 26 of the heat bus 14 and a second portion 35 disposed within a first leg 21 of the heat bus 14. Similarly, the second L-shaped heat pipe 33 comprises a first portion 36 disposed within the base 26 and a second portion 37 disposed within the second leg 23. The base 26 receives heat by conduction from the processor 20 through the thermal interface material 22. Heat is moved from the base 26 to both the first leg 21 and the second leg 23 by conduction through the solid portions 38 of the first leg 21 and the second leg 23 and by evaporation-condensation within the cores 39 of the first and second L-shaped heat pipes 32, 33. Air flow through the air channels 15 removes heat from the fin structure 12 by convection.

FIG. 7A is a section end view of a sixth embodiment of a heat sink 10 of the present invention comprising a honeycomb fin structure 12 coupled to a heat bus 14 that substantially surrounds the fin structure 12. The embodiment of the heat sink 10 of FIG. 7A comprises two U-shaped heat pipes 32, 33, each one open towards the other, to generally surround the fin structure 12. The first and second U-shaped heat pipes 32, 33 comprise hollow cores 39 containing a fluid (not shown) that moves heat from hot locations 40 to cold locations 41 through the evaporation-condensation cycle. The first U-shaped heat pipe 32 comprises a first portion 34 disposed within the base 26 of the heat bus 14, a second portion 35 disposed within a first leg 21 of the heat bus 14, and a third portion 42 disposed within a top 44 of the heat bus 14. The second U-shaped heat pipe 33 comprises a first portion 36 disposed within the base 26, a second portion 37 disposed within the second leg 23 of the heat bus 14 and a third portion 43 disposed within the top 44 of the heat bus 14. The base 26 receives heat by conduction from the processor 20 through the thermal interface material 22. Heat is moved from the base 26 to the first leg 21 and the second leg 23 by conduction through the solid portions 38 of the first leg 21 and the second leg 23 and by evaporation-condensation within the cores 39 of the first and second U-shaped heat pipes 32, 33.

FIG. 7B is a perspective view of the an embodiment of a heat sink 10 comprising a honeycomb fin structure 12 coupled to a heat bus 14 that substantially surrounds the fin structure 12. The heat bus 14 of FIG. 7B comprises a heat spreader 59 having a first leg 21 that terminates at terminus 56 and a second leg 23 that terminates at a terminus 57. The first leg 21 comprises a first portion 58 and a second portion 51. The second leg 23 comprises a first portion 52, a second portion 53 and a third portion 54 extending across a top 55 of the fin structure 12 to terminus 57 of the second leg 23 at a position proximate to the terminus 56 of the first leg 21 to provide a heat bus 14 that substantially surrounds the fin structure 12 to enhance heat distribution to the fin structure 12.

It should be understood that the heat bus 14 of FIG. 7A need not be limited to the two heat pipes 32, 33 and may be, in other embodiments of the present invention, multiple heat pipes or a single extended heat pipe. An embodiment of a heat bus 14 having a single extended heat pipe may comprise a heat pipe having a hollow core 39 that forms a continuous loop that surrounds the fin structure 12. It will be further understood that the heat bus 14 of the heat sink 10 of FIG. 7A will function as a heat spreader if the fluid within the cores 39 is omitted, thereby leaving the heat bus 14 to transfer heat by conduction only. It will be further understood that the heat bus 14 of FIG. 6 would function if a base divider 46 in FIG. 6 that isolates the cores 39 within the first and second legs 21, 23 one from the other is removed to place the cores 39 in fluid communication one with the other, and that the heat bus 14 of FIG. 7A would similarly function if the base divider 46 and the top divider 45 in FIG. 7A that isolate the cores 39 within the first and second legs 21, 23 is removed to place the cores 39 in fluid communication one with the other.

It should also be understood that the heat bus 14 of FIG. 7B could, in another embodiment of the present invention, comprise a hollow fluid-containing core to provide for heat transfer through an evaporation-condensation cycle within the hollow core and for heat transfer through conduction within the solid outer portion of the heat bus 14. It will be further understood that the first leg 21 and the second leg 23 could, in another embodiment, be made continuous and without terminus 56 of the first leg 21 and terminus 57 of the second leg 23 so that heat bus 14 would form a generally continuous conductive structure surrounding the fin structure 12. Still further, any terminus 56, 57 could be centered along the top or otherwise positioned for convenience of efficiency.

The term “repeating,” as that term is used in connection with “repeating interconnected cells,” does not imply any uniformity of shape or size among the cells within the fin structure. To the contrary, as can be seen in FIGS. 1-7B, there are cells (for example, around the interior regions of the cell structure) that appear as regular hexagons, cells that appear as isosceles triangles (near the top and bottom of the fin structure) and cells that appear as trapezoids (along the sides of the fin structure). It is not required that all air channels are identical in cross-section or that all air channels are uniform along their length.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, components and/or groups, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The terms “preferably,” “preferred,” “prefer,” “optionally,” “may,” and similar terms are used to indicate that an item, condition or step being referred to is an optional (not required) feature of the invention.

The corresponding structures, materials, acts, and equivalents of all means or steps plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present invention has been presented for purposes of illustration and description, but it is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. The embodiment was chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.

Claims

1. A heat sink, comprising:

a fin structure having a plurality of repeating, interconnected fin cells allowing the movement of air through the fin cells, the fin structure further having a bottom, a first side and a second side; and

a heat bus having a base to thermally engage a heat-generating electronic component, wherein the heat bus conductively engages and traverses at least a portion of the bottom of the fin structure, at least a portion of the first side of the fin structure, and at least a portion of the second side of the fin structure;

wherein the heat bus facilitates the transfer of heat from the base to the first and second sides of the fin structure; and

wherein the fin structure has lateral conductive pathways to conduct heat from the sides of the fin structure toward a central region of the fin structure.

2. The heat sink of claim 1, wherein the heat bus is a heat spreader with a solid conductive core.

3. The heat sink of claim 1, wherein the heat bus is a heat pipe having a conductive outer portion and a sealed hollow core containing a fluid.

4. The heat sink of claim 1, wherein the fin structure further comprises a top.

5. The heat sink of claim 4, wherein the heat bus engages and traverses at least a portion of the top of the fin structure.

6. The heat sink of claim 1, wherein the heat bus has a U-shaped cross-section.

7. The heat sink of claim 6, wherein the heat bus comprises a U-shaped heat pipe.

8. The heat sink of claim 1, wherein the heat bus comprises a plurality of branches that conductively engage the first side of the fin structure and a plurality of branches that conductively engage the second side of the fin structure.

9. The heat sink of claim 1, wherein the interconnected repeating cells comprise hexagonal cells through which air may pass to cool the fin structure.

10. A heat sink, comprising:

a fin structure having a plurality of interconnected repeating cellular air channels allowing the movement of air there through to remove heat from the fin structure; and

a heat bus having a first portion conductively connected to a bottom of the fin structure, a second portion conductively connected to a first side of the fin structure and a third portion conductively connected to a second side of the fin structure;

wherein the heat bus facilitates the removal of heat from the base to the first side and second side of the fin structure for dissipation to air moving through the air channels of the fin structure.

11. The heat sink of claim 10, wherein the heat bus is a heat spreader with a solid conductive core.

12. The heat sink of claim 10, wherein the heat bus is a heat pipe having a conductive outer portion and a sealed hollow core containing a fluid.

13. The heat sink of claim 10, wherein the heat bus has a fourth portion conductively connected to the top of the fin structure.

14. The heat sink of claim 10, wherein the heat bus has a U-shaped cross-section.

15. The heat sink of claim 14, wherein the heat bus comprises a U-shaped heat pipe.

16. The heat sink of claim 10, wherein the heat bus comprises a plurality of branches that conductively engage the first side of the fin structure and a plurality of branches that conductively engage the second side of the fin structure.

17. The heat sink of claim 10, wherein the interconnected repeating cells comprise hexagonal cells through which air may pass to cool the fin structure.