U.S. patent application number 10/815992 was filed with the patent office on 2005-10-13 for diffusion bonded wire mesh heat sink.
This patent application is currently assigned to PAR Technologies, LLC. Invention is credited to East, W. Joe.
Application Number | 20050224212 10/815992 |
Document ID | / |
Family ID | 35059370 |
Filed Date | 2005-10-13 |
United States Patent
Application |
20050224212 |
Kind Code |
A1 |
East, W. Joe |
October 13, 2005 |
Diffusion bonded wire mesh heat sink
Abstract
A heat sink (20) comprises a heat sink monolith (23) and a cover
(22). The heat sink monolith (23) comprises a thermal transfer
plate (25) and a wire mesh structure (26). The thermal transfer
plate (25) of the monolith (23) and the cover (22) cooperate to
define a heat transfer chamber (24). The wire mesh structure (26)
of the monolith (23) is configured and positioned in the chamber
(24) to provide a tortuous, heat conduction path for fluid (e.g., a
coolant) which turbulently travels from an inlet (40) of the
chamber to one or more outlets (42) of the chamber (24). The wire
mesh structure comprises wires which are fused by diffusion bonding
(rather than by soldering) into a mesh. The diffusion bonding of
the wires provides the wire mesh structure with many and
appropriately sized interstices, making it easier to push the fluid
through the heat sink assembly and thereby significantly reducing
the size and power of the pump which pushes the fluid. Preferably
the diffusion bonded wire mesh structure is integral with or
diffusion bonded to the thermal transfer plate. Within the chamber
the diffusion bonded wire mesh (26) structure can have various
configurations for providing an exposure interface between fluid
pumped through the chamber and the diffusion bonded wire mesh.
Inventors: |
East, W. Joe; (Hampton,
VA) |
Correspondence
Address: |
NIXON & VANDERHYE, PC
901 NORTH GLEBE ROAD, 11TH FLOOR
ARLINGTON
VA
22203
US
|
Assignee: |
PAR Technologies, LLC
Hampton
VA
|
Family ID: |
35059370 |
Appl. No.: |
10/815992 |
Filed: |
April 2, 2004 |
Current U.S.
Class: |
165/80.4 ;
257/E23.098 |
Current CPC
Class: |
B23K 20/02 20130101;
H01L 2924/0002 20130101; B23K 2101/14 20180801; H01L 2924/0002
20130101; H01L 2924/00 20130101; H01L 23/473 20130101; F28F 3/022
20130101 |
Class at
Publication: |
165/080.4 |
International
Class: |
F28F 007/00 |
Claims
What is claimed is:
1. A heat sink assembly comprising: a monolith; a cover which fits
over the monolith to define a chamber, the cover having plural
walls and an inlet through which fluid enters the chamber and an
outlet through which the fluid exits the chamber; wherein the
monolith comprises a thermal transfer plate and a diffusion bonded
wire mesh structure, the wire mesh structure being situated in the
chamber to transfer heat acquired from the thermal transfer plate
to the fluid in the chamber as the fluid travels through
interstices of the wire mesh structure.
2. The heat sink assembly of claim 1, wherein the wire mesh
structure is diffusion bonded to the thermal transfer plate.
3. The heat sink assembly of claim 1, wherein the thermal transfer
plate is comprised of copper.
4. The heat sink assembly of claim 1, wherein the wire mesh
structure is comprised of wire having a diameter in a range from
about 0.0055 inch to about 0.016 inch.
5. The heat sink assembly of claim 1, wherein the wire mesh
structure has a mesh size in a range of less than 100 mesh,
preferably in a range from about 20 to 80 mesh, and more preferably
in a range from and including about 40 mesh to and including about
50 mesh.
6. The heat sink assembly of claim 1, wherein the wire mesh
structure is folded in an essentially serpentine configuration
within the chamber.
7. The heat sink assembly of claim 1, wherein the wire mesh
structure is folded at fold axes in an essentially serpentine
configuration within the chamber, and wherein a path of the fluid
in the chamber from the inlet to the outlet is not parallel to the
fold axes.
8. The heat sink assembly of claim 1, wherein the wire mesh
structure is folded at fold axes in an essentially serpentine
configuration within the chamber, and wherein a path of the fluid
in the chamber from the inlet to the outlet is substantially
perpendicular to the fold axes.
9. The heat sink assembly of claim 1, wherein the cover has is an
essentially parallelepiped with one open face and four side walls,
wherein the wire mesh structure is folded at fold axes in an
essentially serpentine configuration within the chamber, and the
inlet and the outlet are provided on opposing sidewalls that are
parallel to the fold axes.
10. The heat sink assembly of claim 1, wherein the wire mesh
structure has an essentially spiral configuration within the
chamber.
11. The heat sink assembly of claim 1, wherein the wire mesh
structure has an essentially circular configuration within the
chamber.
12. The heat sink assembly of claim 11, wherein the wire mesh
structure is configured to comprise plural concentric rings within
the chamber.
13. The heat sink assembly of claim 1, wherein the cover has an
essentially parallelepiped shape with an open face and has four
side walls, and a port wall which is opposite the thermal transfer
plate, and wherein the inlet and the outlet are provided on the
port wall.
14. The heat sink assembly of claim 13, wherein the inlet is
provided in the center of the port wall.
15. The heat sink assembly of claim 13, wherein the outlet is
provided proximate a corner of the port wall.
16. The heat sink assembly of claim 13, further comprising plural
outlets, and wherein each of the plural outlets is provided
proximate a respective corner of the port wall.
17. The heat sink assembly of claim 1, wherein the cover has an
essentially 2 parallelepiped with one open face, four side walls,
and a port wall which is opposite 3 and parallel to the thermal
transfer plate, and wherein the port wall has a channel 4 formed
therein so that fluid is communicated through the channel in a
direction that is essentially parallel to a plane of the thermal
transfer plate.
18. A heat dissipation system comprising: a body to be cooled; a
heat sink assembly comprising: a monolith; a cover which fits over
the monolith to define a chamber, the cover having plural walls and
an inlet through which fluid enters the chamber and an outlet
through which the fluid exits the chamber; wherein the monolith
comprises a thermal transfer plate and a diffusion bonded wire mesh
structure, wherein the thermal transfer plate is situated in heat
conducting relation with the body to be cooled, wherein the wire
mesh structure is situated in the chamber to transfer heat acquired
from the thermal transfer plate to the fluid in the chamber as the
fluid travels through interstices of the wire mesh structure a pump
which pumps fluid through a circulation path including the heat
sink assembly.
19. The heat dissipation system of claim 18, further comprising a
heat exchanger included in the circulation path, the circulation
path being configured so that after the heat is transferred to the
fluid in the heat sink assembly the fluid is cooled by the heat
exchanger prior to the fluid being circulated back to the heat sink
assembly
20. The heat dissipation system of claim 18, wherein the wire mesh
structure is diffusion bonded to the thermal transfer plate.
21. The heat dissipation system of claim 18, wherein the thermal
transfer plate is comprised of copper.
22. The heat dissipation system of claim 18, wherein the diffusion
bonded wire mesh structure is comprised of wire having a gauge in a
range from about 0.0055 inch to about 0.016 inch.
23. The heat dissipation system of claim 18, wherein the wire mesh
structure has a mesh size in a range of less than 100 mesh,
preferably in a range from about 20 to 80 mesh, and more preferably
in a range from and including about 40 mesh to and including about
50 mesh.
24. The heat dissipation system of claim 18, wherein the wire mesh
structure is folded in an essentially serpentine configuration
within the chamber.
25. The heat dissipation system of claim 18, wherein the wire mesh
structure is folded at fold axes in an essentially serpentine
configuration within the chamber, and wherein a path of the fluid
in the chamber from the inlet to the outlet is not parallel to the
fold axes.
26. The heat dissipation system of claim 18, wherein the wire mesh
structure is folded at fold axes in an essentially serpentine
configuration within the chamber, and wherein a path of the fluid
in the chamber from the inlet to the outlet is substantially
perpendicular to the fold axes.
27. The heat dissipation system of claim 18, wherein the cover has
is an essentially parallelepiped with one open face and four side
walls, wherein the wire mesh structure is folded at fold axes in an
essentially serpentine configuration within the chamber, and the
inlet and the outlet are provided on opposing sidewalls that are
parallel to the fold axes.
28. The heat dissipation system of claim 18, wherein the wire mesh
structure has an essentially spiral configuration within the
chamber.
29. The heat dissipation system of claim 18, wherein the wire mesh
structure has an essentially circular configuration within the
chamber.
30. The heat dissipation system of claim 29, wherein the wire mesh
structure is configured to comprise plural concentric rings within
the chamber.
31. The heat dissipation system of claim 18, wherein the cover has
an essentially parallelepiped shape with an open face and has four
side walls, and a port wall which is opposite the thermal transfer
plate, and wherein the inlet and the outlet are provided on the
port wall.
32. The heat dissipation system of claim 31, wherein the inlet is
provided in the center of the port wall.
33. The heat dissipation system of claim 31, wherein the outlet is
provided proximate a corner of the port wall.
34. The heat dissipation system of claim 31, further comprising
plural outlets, and wherein each of the plural outlets is provided
proximate a respective corner of the port wall.
35. The heat dissipation system of claim 18, wherein the cover is
an essentially parallelepiped with one open face, four side walls,
and a port wall which is opposite and parallel to the thermal
transfer plate, and wherein the port wall has a channel formed
therein so that fluid is communicated through the channel in a
direction that is essentially parallel to a plane of the thermal
transfer plate.
36. A heat sink monolith comprising: a thermal transfer plate; a
diffusion bonded wire mesh structure secured to the thermal
transfer plate.
37. The heat sink monolith of claim 36, wherein the wire mesh
structure is diffusion bonded to the thermal transfer plate.
38. The heat sink monolith of claim 36, wherein the thermal
transfer plate is comprised of copper.
39. The heat sink monolith of claim 36, wherein the wire mesh
structure is comprised of wire having a gauge in a range from about
0.0055 inch to about 0.016 inch.
40. The heat sink monolith of claim 36, wherein the wire mesh
structure has a mesh size in a range of less than 100 mesh,
preferably in a range from about 20 to 80 mesh, and more preferably
in a range from and including about 40 mesh to and including about
50 mesh.
41. The heat sink monolith of claim 36, wherein the wire mesh
structure is folded in an essentially serpentine configuration.
42. The heat sink monolith of claim 36, wherein the wire mesh
structure has an essentially spiral configuration.
43. The heat sink monolith of claim 36, wherein the wire mesh
structure has an essentially circular configuration.
44. The heat sink monolith of claim 43, wherein the wire mesh
structure is configured to comprise plural concentric rings.
Description
BACKGROUND
[0001] 1. Field of the Invention
[0002] This invention pertains to heat sinks, and particularly to
heat sinks which are cooled by a circulating fluid.
[0003] 2. Related Art and Other Considerations
[0004] Various types of equipment create or release heat during
operation. In some cases the heat can be injurious to the equipment
or its environment (e.g., other equipment or components in
proximity to the heat-generating or heat-releasing equipment).
Accordingly, attempts have been made in some such cases to cool the
equipment and/or its environs. Common cooling techniques include
circulation of a cooling fluid around or near the source of heat.
For example, fans have been used to blow cooling air around a
heat-generating component of a system. Alternatively, heat pipes or
other types of heat sinks have been placed in contact or nearby the
heat source for the purpose of dissipating the heat using, e.g.,
circulating air.
[0005] Among the types of equipment prone to heat
generation/release are some electronic components, such as
microprocessors, for example. As microprocessor manufacturers are
running the microprocessor chips at higher and higher frequencies
in order to obtain maximum performance, the chips can build up
enough heat to cause failures. In fact, the heat can become so
great in many chips that conventional means of cooling (e.g., fans
and heat pipes) are not sufficiently effective.
[0006] In view of the inadequacy of conventional cooling
techniques, fluid cooling of heat generating/releasing components
(e.g., electronic chips) is gaining momentum. For example, for
cooling purposes a fluid is pumped through a heat sink in contact
with the chip die to pick up heat from the chip die. The fluid is
then pumped to a heat exchanger for cooling the fluid before the
fluid is routed back to the heat sink to pick up and remove more
heat.
[0007] Some fluid-accommodating heat sinks employ microchannel
technology. That is, the heat sinks have "microchannels" through
which the cooling fluid travels as it is pumped. The microchannels
are very small channels formed in or on a heat sink surface, or the
chip die. The heat sink surface with the microchannels may be flush
with or otherwise in contact with a surface of a device to be
cooled (e.g., chip die).
[0008] Despite their proven potential for handling high heat
fluxes, microchannel-based heat sinks have not found widespread
commercial use, possibly due to the very high pressure drops
encountered in the microchannels. High pressure drops necessitate
the use of relatively large pumps with significant power
requirements, noise, reliability issues, and associated costs.
[0009] Moreover, there can be a problem if bubbles form in
microchannel-type heat sinks. When a bubble forms in a microchannel
of a heat sink, the bubble tends not to exit the channel. Instead,
the bubble remains essentially stationary in the microchannel.
Since the remaining bubble occludes the cooling fluid flow, a hot
spot may develop in or on the device being cooled. If the hot spot
grows significantly, the device being cooled may fail.
[0010] What is needed, therefore, and an object of this invention,
is an efficient and effective heat sink.
BRIEF SUMMARY
[0011] A heat sink assembly comprises a monolithic heat sink
monolith and a cover. The monolithic heat sink monolith comprises a
thermal transfer plate and a wire mesh diffusion bonded to form a
monolithic structure, i.e., totally uniform material. The thermal
transfer plate of the monolith and the cover cooperate to define a
heat transfer chamber. The wire mesh structure of the monolith is
configured and positioned in the chamber to provide a tortuous,
heat conduction path for fluid (e.g., a coolant) which turbulently
travels from an inlet of the chamber to one or more outlets of the
chamber.
[0012] The monolithic heat sink comprises a wire mesh formed into a
tightly wound spiral which is fused by diffusion bonding (rather
than by soldering) onto the thermal transfer plate, as well as
being fused to itself. The diffusion bonding of the wires provides
the wire mesh structure with many and appropriately sized
interstices, making it easier to push the fluid through the heat
sink assembly and thereby significantly reducing the size and power
of the pump which pushes the fluid. Stated differently, the
diffusion bonded mesh functions similarly to the microchannel, but
with, e.g., greater numbers of fluidic paths and thus far less
pressure drop. Further, the heat transfer efficiency is increased
due to the fact that the diffusion bonded wire mesh structure has
such a large surface area, up to five to ten times more that a
standard microchannel heat sink
[0013] The wire mesh structure can be secured or adhered to the
thermal transfer plate by numerous conventional techniques such as
(for example) soldering, welding, radio frequency (RF) melting, and
adhesives which are cured or activated (e.g., by heat, by voltage,
etc.). Preferably the wire mesh structure is diffusion bonded to
the thermal transfer plate in a same operation in which the wires
of the wire mesh structure are bonded together. The diffusion
bonding of the wire mesh structure to the thermal transfer plate to
create the monolith allows for higher efficiency in transferring
heat from the thermal transfer plate to the wire mesh
structure.
[0014] Within the chamber the diffusion bonded wire mesh structure
can have various configurations for providing an exposure interface
between fluid pumped through the chamber and the diffusion bonded
wire mesh. In one example embodiment, the diffusion bonded wire
mesh structure is folded in an essentially serpentine configuration
within the chamber. A path of the fluid in the chamber from the
inlet to the outlet is preferably not parallel to the fold axes,
and more preferably is substantially perpendicular to the fold
axes. In one non-limiting implementation of this embodiment in
which the housing has an essentially parallelepiped shaped and
includes the thermal transfer plate and four side walls, the inlet
and the outlet are provided on opposing sidewalls that are parallel
to the fold axes.
[0015] In another example embodiment, the diffusion bonded wire
mesh structure has an essentially spiral configuration within the
chamber. In yet another example embodiment, the diffusion bonded
wire mesh structure has an essentially circular configuration
within the chamber, and preferably is configured to comprise plural
concentric rings within the chamber. In certain example
implementations of the spiral and circular/concentric embodiments
in which the housing has an essentially parallelepiped shape, the
housing includes the thermal transfer plate, four side walls, and a
port wall which is opposite the thermal transfer plate, with the
inlet and the outlet being provided on the port wall. In one
implementation, the inlet and outlet communicate through respective
channels formed in the port wall so that fluid travels through the
channels in a direction which is essentially parallel to a plane of
the thermal transfer plate. In this manner, fluid is introduced
centrally into the chamber and pumped to one or more corners of the
housing. In embodiments in which the housing has plural outlets,
downstream from the outlets the outlets may be connected to a
common discharge tube.
[0016] The heat sinks are useful in a heat dissipation system in
which the thermal transfer plate of the heat sink is situated in
heat conducting relation with a body to be cooled, and which
further includes a heat exchanger and a pump. The pump serves to
move fluid through a circulation path including the heat sink and
the heat exchanger. The circulation path is configured so that
after the heat is transferred to the fluid in the heat sink, the
fluid is cooled by the heat exchanger prior to the fluid being
circulated back to the heat sink.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1A is a perspective top and side view of a heat sink
assembly according to a first example embodiment.
[0018] FIG. 1B is a bottom view of the heat sink assembly of FIG.
1A taken along the line 1B-1B.
[0019] FIG. 1C is a side view of the heat sink assembly of FIG. 1A
taken along the line 1C-1C.
[0020] FIG. 2A is a perspective top and side view of a heat sink
assembly according to a second example embodiment.
[0021] FIG. 2B is a bottom view of the heat sink assembly of FIG.
2A taken along the line 2B-2B.
[0022] FIG. 2C is a side view of the heat sink assembly of FIG. 2A
taken along the line 2C-2C.
[0023] FIG. 3A is a perspective top and side view of a heat sink
assembly according to a second example embodiment.
[0024] FIG. 3B is a bottom view of the heat sink assembly of FIG.
3A taken along the line 3B-3B.
[0025] FIG. 3C is a side view of the heat sink assembly of FIG. 3A
taken along the line 3C-3C.
[0026] FIG. 4A is a top view of a monolith for a heat sink assembly
according to a fourth example embodiment.
[0027] FIG. 4B is a side view of the monolith of FIG. 4A.
[0028] FIG. 4C is a bottom view of a cover for the monolith of FIG.
4A.
[0029] FIG. 4D is a front side view of the cover of FIG. 4C taken
along the line 4D-4D.
[0030] FIG. 4E is a left side view of the cover of FIG. 4C.
[0031] FIG. 4F is a front side view of the cover of FIG. 4C taken
along the line 4F-4F.
[0032] FIG. 5A is a top view of a monolith for a heat sink assembly
according to a fifth example embodiment.
[0033] FIG. 5B is a side view of the monolith of FIG. 5A.
[0034] FIG. 5C is a bottom view of a cover for the monolith of FIG.
5A.
[0035] FIG. 5D is a front side view of the cover of FIG. 5C taken
along the line 5D-4D.
[0036] FIG. 5E is a right side view of the cover of FIG. 5C.
[0037] FIG. 6A-FIG. 6E are schematic views of differing, example
heat dissipation systems which include a representative, generic
heat sink assembly.
DETAILED DESCRIPTION
[0038] In the following description, for purposes of explanation
and not limitation, specific details are set forth such as
particular architectures, interfaces, techniques, etc. in order to
provide a thorough understanding of the present invention. However,
it will be apparent to those skilled in the art that the present
invention may be practiced in other embodiments that depart from
these specific details. In other instances, detailed descriptions
of well-known devices, circuits, and methods are omitted so as not
to obscure the description of the present invention with
unnecessary detail.
[0039] Heat sink assemblies as described herein are advantageously
formed to comprise a heat sink monolith and a cover. The heat sink
monolith comprises a thermal transfer plate and a wire mesh
structure. The thermal transfer plate of the monolith and the cover
cooperate to define a heat transfer chamber. The wire mesh
structure of the monolith is configured and positioned in the
chamber to provide a tortuous, heat conduction path for fluid
(e.g., a coolant, such as a liquid coolant) which turbulently
travels from an inlet of the chamber to one or more outlets of the
chamber. As such, the fluid travels through the chamber in
essentially every direction, moving with turbulence and thereby
increasing heat transfer capability.
[0040] The wire mesh structure comprises wires which are fused by
diffusion bonding (rather than by soldering) into a mesh. For
example, the wires comprising the wire mesh structure are fused as
a diffusion bond is formed between tangent metal surfaces when
enough atoms or molecules migrate between them to create new
metallurgical grains which bridge the gap.
[0041] The diffusion bonding of the wires provides the wire mesh
structure with many and appropriately sized interstices, making it
easier to push the fluid through the heat sink assembly and thereby
significantly reducing the size and power of the pump which pushes
the fluid. Further, the heat transfer efficiency is increased due
to the fact that the diffusion bonded wire mesh structure has such
a large surface area. This greater surface area provided by the
wire mesh structure facilitates more exposure of the fluid to the
heat transferring metal, and thus a lesser degree of fluid flow,
and hence less pressure required for pumping the fluid through the
chamber of the heat sink assembly.
[0042] Described herein are non-limiting, representative example
embodiments which position a diffusion bonded wire mesh structure
in a heat transfer chamber of a heat sink assembly. The heat
transfer chamber ("chamber" for short) is primarily defined by a
heat transfer plate of the monolith and a cover. The cover has an
outlet and an inlet. In the chamber the diffusion bonded wire mesh
structure can have various configurations for providing an exposure
interface between fluid pumped through the chamber and the
diffusion bonded wire mesh. Heat sink assemblies other than those
particularly illustrated and described herein are within the
purview of the invention. Moreover, the invention is not confined
to any particular configuration of one or more elements comprising
the heat sink assembly, e.g., not confined to any configuration of
the diffusion bonded wire mesh structure or of the chamber or of
the cover.
[0043] FIG. 1A, FIG. 1B, and FIG. 1C illustrate a first example
embodiment of a heat sink assembly 20-1. The heat sink 20-1
comprises a cover 22-1 and a heat sink monolith 23-1. The cover
22-1 fits over the monolith 23-1 so that a heat transfer chamber
24-1 is defined therein. The monolith 23-1 comprises a thermal
transfer plate 25-1 with is integral with a diffusion bonded wire
mesh structure 26-1. As in all embodiments described herein, the
thermal transfer plate 25-1 is a conductive metal, and preferably
the same metal (e.g., copper) as the metal which forms the wires of
the wire mesh structure. The wire mesh structure 26-1 of the
monolith 23-1 extends into the chamber 24-1.
[0044] Like covers of other example embodiments illustrated herein,
the cover 22-1 is essentially a parallelepiped. In fact, the cover
22-1 of the first embodiment is a rectangular parallelepiped having
one open face. As such, the cover 22-1 has five walls. The walls of
the cover 22-1 include side walls 31-1, 32-1, 33-1, and 34-1, as
well as cover wall 35-1. The cover wall 35-1 lies in a plane which
is parallel to thermal transfer plate 25-1. When the heat sink
assembly is assembled, the open face of cover 22--is closed by
thermal transfer plate 25-1. FIG. 1A, FIG. 1B, and FIG. 1C show the
heat sink assembly 20-1 with thermal transfer plate 25-1
surmounting the cover 22-1.
[0045] The thermal transfer plate 25-1 can be secured to cover 22
by any suitable fasteners or adhesives such as, e.g., threaded
fasteners. FIG. 1B shows the interior of the chamber looking up
from cover wall 35-1 toward the underside of thermal transfer plate
30-1, thereby also permitting a view of the diffusion bonded wire
mesh structure 26-1.
[0046] Cover 22-1 has an inlet 40-1 through which fluid enters the
chamber 24-1 and an outlet 42-1 through which the fluid exits the
chamber 24-1. In the first embodiment, the inlet 40-1 and the
outlet 42-1 are provided on opposing sidewalls 31-1 and 33-1,
respectively, of cover 22-1. Other inlet/outlet arrangements are
also possible, including plural inlets on one sidewall and opposing
outlets on an opposing sidewall, with inlet(s) and outlet(s) being
aligned or non-aligned, etc.
[0047] As with all embodiments described herein, the wire mesh
structure 26-1 can be secured or adhered to the thermal transfer
plate 25-1 by numerous conventional techniques such as (for
example) soldering, welding, radio frequency (RF) melting, and
adhesives which are cured or activated (e.g., by heat, by voltage,
etc.). The monolithic heat sink comprises a wire mesh formed into a
tightly wound spiral which is fused by diffusion bonding (which
could be done by soldering, welding, and/or epoxying as well as
diffusion bonding to create the monolithic structure) onto the
thermal transfer plate as well as being fused to itself. Preferably
in all embodiments the wire mesh structure is diffusion bonded to
the thermal transfer plate in a same operation in which the wires
of the wire mesh structure are bonded together. The diffusion
bonding of the wire mesh structure to the thermal transfer plate to
create the monolith allows for higher efficiency in transferring
heat from the thermal transfer plate to the wire mesh
structure.
[0048] The diffusion bonded wire mesh structure 26-1 is situated in
the chamber 24-1 to transfer heat acquired from the thermal
transfer plate 30-1 to the fluid in the chamber 24-1 as the fluid
is pumped through interstices of the diffusion bonded wire mesh
structure 26-1. The wire mesh structure of the monolith is
configured and positioned in the chamber to provide a tortuous,
heat conduction path for fluid (e.g., a coolant) which turbulently
travels from the inlet 40-1 of the chamber to one or more outlets
42-1 of the chamber.
[0049] As shown in FIG. 1C, the diffusion bonded wire mesh
structure 26-1 of the first embodiment is folded in an essentially
serpentine configuration within the chamber. One such fold axis for
the diffusion bonded wire mesh structure 26-1 is depicted as axis
44, which essentially lies along a line parallel to planes of wide
wall 31-1 and side wall 33-1. Fold axes are provided at each crest
and trough of the serpentine diffusion bonded wire mesh structure
26-1. The fold axes may comprise right angle bends in the manner
shown in FIG. 1C, or alternatively may be curved so that the
serpentine diffusion bonded wire mesh structure 26-1 has more of an
undulating shape rather than the strict zig-zag shape shown in FIG.
1C.
[0050] Due to pumping action, in operation a fluid travels through
chamber 24-1 from the inlet 40-1 to the outlet 42-1. Some of the
paths of the fluid in the chamber from the inlet 40-1 to the outlet
42-1 are generally depicted by arrows 46-1 in FIG. 1B and FIG. 1C.
The paths of fluid travel are thus preferably not parallel to the
fold axes 44-1, and more preferably some paths are substantially
perpendicular to the fold axes 44-1. Such paths are facilitated by
the fact that the inlet 40-1 and the outlet 42-1 are provided on
opposing sidewalls 31-1, 33-1, respectively, that are parallel to
the fold axes 44-1.
[0051] FIG. 2A, FIG. 2B, and FIG. 2C illustrate a second example
embodiment of a heat sink assembly 20-2. Unless otherwise excepted
specifically or by context, comments concerning the first
embodiment are also applicable to the second example embodiment and
other embodiments described herein. For example, the heat sink 20-2
comprises a cover 22-2 which cooperates with monolith 23-2 to
define chamber 24-2. A diffusion bonded wire mesh structure 26-2 of
monolith 23-2 is situated in chamber 24-2. The cover 22-2 is
essentially a square parallelepiped having an open face and has
five walls including side walls 31-2, 32-2, 33-2, and 34-2, as well
as cover wall 35-2.
[0052] In the orientation of FIG. 2A the cover 22-2 is the
uppermost, with thermal transfer plate 30-2 being surmounted by
cover 22-2. The thermal transfer plate 30-2 has the diffusion
bonded wire mesh structure 26-2 secured to an inside surface
thereof by, e.g., diffusion bonding. FIG. 2B shows the interior of
the chamber looking up from thermal transfer plate 30-2 toward the
underside of cover wall 35-2, thereby also permitting a view of the
diffusion bonded wire mesh structure 26-2.
[0053] In the second embodiment, the cover wall 35-2 of cover 22-2
includes both a single inlet 40-2, as well as plural (e.g., four)
outlets 42-2. In the illustrated version of the second embodiment,
the single inlet is centrally located, while each of the four
outlets 42-2 are situated in (e.g., proximate) a separate corner of
cover wall 35-2. Other inlet/outlet arrangements are also possible,
including plural inlets; greater or lesser than four outlets;
differing placements on the cover wall 35-2 of the inlet(s) and/or
outlet(s); or even providing the inlet(s) and/or outlet(s) on other
walls of cover 22-2.
[0054] As in the other embodiments, the diffusion bonded wire mesh
structure 26-2 is situated in the chamber 24-2 to transfer heat
acquired from the thermal transfer plate 30-2 to the fluid in the
chamber 24-2 as the fluid is pumped through interstices of the
diffusion bonded wire mesh structure 26-2. As mentioned previously,
preferably the diffusion bonded wire mesh structure is formed
integrally with or bonded to the thermal transfer plate 30-2 (e.g.,
diffusion bonded in the same operation in which the wires of the
wire mesh structure are bonded). As shown in FIG. 2C, the diffusion
bonded wire mesh structure 26-2 of the second embodiment has an
essentially spiral configuration within the chamber. The spiral
pattern of the diffusion bonded wire mesh structure 26-2 has a
first end near the center of the chamber 24-2 (e.g., near the inlet
40-2), and spirals radially outward toward the side walls of
chamber 22-2.
[0055] Due to pumping action, in operation a fluid enters the
chamber 24-2 through inlet 40-2 and is directed downward to impinge
against the thermal transfer plate 25-2. The impingement action of
the fluid against thermal transfer plate 25-2 creates a turbulence
in the fluid. The turbulence is beneficial so that a laminar
barrier of fluid does not reside on thermal transfer plate 25-2,
since a laminar barrier of fluid would tend to buffer the incoming
fluid from the heat transfer of the thermal transfer plate 25-2.
Moreover, the turbulence to the fluid imparted by the impingement
action of the incoming fluid on the thermal transfer plate 25-2
serves to scatter the fluid after the impingement into
multitudinous directions and paths through the wire mesh structure
26-2 and thus through the chamber 24-2 toward the outlets 42-2.
Some of the paths of the fluid in the chamber from the inlet 40-2
to the outlet 42-2 are generally depicted by arrows 46-2 in FIG. 2B
and FIG. 2C.
[0056] FIG. 3A, FIG. 3B, and FIG. 3C illustrate a third example
embodiment of a heat sink assembly 20-3. Unless otherwise excepted
specifically or by context, comments concerning the first
embodiment are also applicable to the third example embodiment. For
example, the heat sink 20-3 cover 22-3 which cooperates with
monolith 23-3 to define chamber 24-3. A diffusion bonded wire mesh
structure 26-3 of monolith 23-3 is situated in chamber 24-3. The
cover 22-3 is essentially a square parallelepiped having an open
face and has five walls including side walls 31-3, 32-3, 33-3, and
34-3, as well as cover wall 35-3.
[0057] As in the other embodiments, the diffusion bonded wire mesh
structure 26-3 is situated in the chamber 24-3 to transfer heat
acquired from the thermal transfer plate 30-3 to the fluid in the
chamber 24-3 as the fluid first impinges upon thermal transfer
plate 25-3 and then is pumped through interstices of the diffusion
bonded wire mesh structure 26-3. As mentioned previously,
preferably the diffusion bonded wire mesh structure is formed
integrally with or bonded to the thermal transfer plate 30-3 (e.g.,
diffusion bonded in the same operation in which the wires of the
wire mesh structure are bonded). As shown in FIG. 3C, the diffusion
bonded wire mesh structure 26-3 of the third embodiment has an
essentially circular configuration within the chamber, and
preferably is configured to comprise plural concentric rings within
the chamber.
[0058] FIG. 4A-FIG. 4F illustrate components of a fourth example
embodiment of a heat sink assembly. Unless otherwise excepted
specifically or by context, comments concerning the previous
embodiments are also applicable to the fourth example embodiment.
FIG. 4A and FIG. 4B show monolith 23-4 with its thermal transfer
plate 25-4 and its integral wire mesh structure 26-4. FIG. 4C-FIG.
4F show cover 22-4 for the fourth embodiment.
[0059] The thermal transfer plate 30-4 has the diffusion bonded
wire mesh structure 26-4 secured to an inside surface thereof by,
e.g., diffusion bonding. Although not illustrated in detail in FIG.
4A and FIG. 4B, the wire mesh structure 26-4 can have any suitable
configuration. For example, the configuration of wire mesh
structure 26-4 can be either the circular configuration of the
third embodiment or, more preferably for ease of fabrication, the
spiral configuration of the second embodiment. The wire mesh
structure 26-4 has an outer diameter and an inner diameter,
illustrated in FIG. 4A as OD.sub.25-4 and ID.sub.25-4,
respectively. The wire mesh structure 26-4 has a center axis 35-4
which extends essentially orthogonally from the thermal transfer
plate 25-4.
[0060] Although the mating of cover 22-4 and monolith 23-4 is not
illustrated for the fourth embodiment, it will be appreciated that
cover 22-4 fits over monolith 23-4 to define a chamber in similar
manner as previously described embodiments. To this end, fastener
holes are provided in aligned fashion proximate corners of both
thermal transfer plate 25-4 and cover 22-4. The cover 22-4 is
essentially a square parallelepiped having an open face and has
five walls including side walls 31-4, 32-4, 33-4, and 34-4, as well
as cover wall 35-4. The cover 22-4 fits over thermal transfer plate
30-4.
[0061] In the fourth embodiment, the cover wall 35-4 of cover 22-4
includes both a single inlet 40-4, as well as plural (e.g., four)
outlets 42-4 (see FIG. 4D). In the illustrated version of the
second embodiment, the single inlet 40-4 is centrally located,
while each of the four outlets 42-4 are situated in (e.g.,
proximate) a separate corner of cover wall 35-4. The inlet 40-4
communicates through an inlet channel 50-4 formed in cover 22-4
with an inlet port 51-4 provided on sidewall 31-4 of cover 22-4.
The inlet port 51-4 can be threaded or otherwise configured to
receive or mate with a tube coupler or the like. Similarly, a pair
of two adjacent outlets 42-4 communicate through an associated
outlet channel 52-4 to a respective outlet port 53-4 provided on
sidewall 33-4 of cover 22-4. The outlet ports 53-4 can also be
threaded or otherwise configured to receive or mate with a tube
coupler or the like. In the illustrated implementation of the
fourth embodiment, the inlet channel 51-4 and the outlet channels
53-4 are perpendicular to the axis of wire mesh structure 26-4, and
thus parallel to the plane of thermal transfer plate 25-4. Further,
the inlet channel 51-4 and the outlet channels 53-4 have major axes
which are parallel to one another. In one example implementation of
the fourth embodiment, the diameter of the inlet channel 51-4 is
about 0.135 inch while the diameter of the outlet channels is about
0.125 inch. The inlet 40-4 in cover 22-4 has a diameter depicted as
D.sub.40.
[0062] The orientation of the inlet channel 51-4 and the outlet
channels 53-4 as shown with respect to the fourth embodiment
facilitates routing of fluid to the heat sink assembly in a
direction which is parallel to the plane of thermal transfer plate
25-4, thereby resulting in a shorter form factor which is
advantageous for some devices, such as electronic devices including
(for example) laptop computers. Other inlet/outlet arrangements are
also possible, including further inlets; greater or lesser than
four outlets; and differing placements of the inlet(s) and/or
outlet(s).
[0063] One example of a different inlet/outlet configuration is
shown in a fifth embodiment illustrated in FIG. 5A-FIG. 5E.
Elements of the fifth embodiment which are common to the fourth
embodiment have similarly numbered reference numerals (excepting
suffixes which correspond to the embodiment number). The fifth
embodiment essentially differs from the fourth embodiment in that
the inlet 40-5 of the fifth embodiment is formed parallel to the
axis 35-5 of wire mesh structure 26-5. Thus, the direction of fluid
flow
[0064] Preferably the diameter D.sub.40 of the inlets 40-4 and 40-5
is greater than the inner diameter ID.sub.25-4 of the respective
wire mesh structures 26-4 and 26-5. An example and preferred value
for the diameter D.sub.40 of the inlets 40 is 0.171 inch. By having
diameter D.sub.40 of the inlets 40 be greater than the inner
diameter ID.sub.25 of the wire mesh structures 26, the fluid
introduced into the center of the wire mesh structure 26 is
constrained into a smaller volume and rebuffed by the wires at the
center of wire mesh structure 26. Such constraint and interaction
causes turbulence in the fluid and increases the pressure involved
in the impingement of the incoming fluid on thermal transfer plate
25. As indicated previously, the impingement on thermal transfer
plate 25 causes a further degree of turbulence, which
advantageously facilitates greater exposure of the fluid to the
metal comprising monolith 23 and thus increased thermal
transfer.
[0065] In the fourth embodiment, the right angle bend in the path
of the fluid when leaving inlet channel 50-4 and traveling through
inlet 40-4 also introduces a measure of turbulence to the incoming
fluid. Other ways of providing increased turbulence can also be
provided, such as surface irregularities in inlet channel 50-4.
[0066] As in the other embodiments, the diffusion bonded wire mesh
structures 26 of the fourth and fifth embodiments are situated in
the chamber 24 to transfer heat acquired from the thermal transfer
plate 30 to the fluid in the chamber 24 as the fluid is pumped
through interstices of the diffusion bonded wire mesh structure 26.
As mentioned previously, preferably the diffusion bonded wire mesh
structure is formed integrally with or bonded to the thermal
transfer plate 30 (e.g., diffusion bonded in the same operation in
which the wires of the wire mesh structure are bonded).
[0067] Heat sinks such as the example heat sink assemblies
described by way of the non-limiting and representative examples
above are useful in a heat dissipation system in which the thermal
transfer plate of the heat sink is situated in heat conducting
relation with a body to be cooled, and which further includes a
pump and optionally includes a heat exchanger. Although the
embodiments illustrated herein include a heat exchange, it is
possible in some applications that the heat exchanger may be
omitted if there is sufficient cooling of the cooling fluid by
remaining elements of the system.
[0068] FIG. 6A illustrates one such heat dissipation system 60A
wherein thermal transfer plate 30A of heat sink 20A is in heat
conducting relation with body to be cooled 62. An output side of
pump 64 is connected by tube 65 to inlet 40 of heat sink 20A. An
outlet 42 of heat sink 20A is connected by tube 66 to an intake
port of heat exchanger 68. An output port of heat exchanger 68 is
connected to an intake side of pump 64. The pump 64 serves to move
fluid through a circulation path including tube 65, heat sink 20A,
tube 66, heat exchanger 68, and tube 69. The circulation path is
configured so that after the heat is transferred to the fluid in
the heat sink 20A, the fluid is cooled by the heat exchanger 68
prior to the fluid being circulated back to the heat sink 20A.
[0069] While the heat dissipation system of FIG. 6A is more
appropriate for a heat sink having a single inlet and single outlet
such as heat sink 20-1 previously described, other versions of
appropriate heat dissipation systems can also be designed. For
example, the heat dissipation system of FIG. 6B is suitable for a
heat sink (such as heat sinks 20-2 and 20-3) having multiple
outlets 42. FIG. 6B shows each of the four outlets 42 being
connected to an associated tube 66, with the four tubes 66 being
connected together or otherwise joined into a single tube 67. FIG.
6B thus illustrates that, in embodiments in which the housing has
plural outlets 42, downstream from the outlets the outlets may be
connected to a common discharge tube.
[0070] FIG. 6C shows by way of illustration that the pump 64C may
be proximate to or formed integral with heat sink assembly 20C.
Such juxtaposition of pump and sink can be utilized for various
embodiments, not just the particular configuration shown in FIG.
6C.
[0071] FIG. 6D and FIG. 6E show example heat dissipation systems
which can be respectively utilized for the fourth and fifth
above-described embodiments of heat sink assemblies. The FIG. 6D
heat dissipation system is particularly attractive for its low form
factor, especially when the pump 64D, heat sink 20D, and (optional)
heat exchanger 68 are located in essentially planar fashion.
[0072] In the heat dissipating systems contemplated herein, the
body to be cooled 62 can be any body which generates or radiates
heat, such as a die for a microprocessor or other electronic chip,
for example. In such case, FIG. 6A and FIG. 6B illustrate a closed
loop electronic cooling application for picking up heat generated
by a microprocessor or other electronic device.
[0073] The diffusion bonded wire mesh structure is comprised of
wire having a suitable gauge and mesh size for the intended
application. Mesh size refers to the number of wire strands per
linear inch. It is believed that selection of wire gauge and mesh
size is interdependent. For a heat sink utilized for the cooling of
electronic the diffusion bonded wire mesh structure can have, e.g.,
a diameter in a range from about 0.0055 inch to about 0.016 inch,
and a mesh size less than 100, preferably in a range from about 20
to 80 mesh, and more preferably in a range from and including about
40 mesh to and including about 50 mesh.
[0074] The height of the wire mesh structures 26 described herein,
i.e., the extent of the wire mesh structures in a distance
perpendicular to the plane of the thermal transfer plate 25, is
preferably in a range of from about 0.125 inch to about 0.375
inch.
[0075] The fusing of the wire in the diffusion bonded wire mesh
structures allows for higher efficiency in transferring heat from a
plate to the diffusion bonded wire mesh. The fusing results in very
many channels or interstices in the diffusion bonded wire mesh,
making it easier to push the fluid through the heat sink and
thereby significantly reducing the size and power of the pump which
pushes the fluid. Moreover, the heat transfer efficiency is
increased due to the fact that the diffusion bonded wire mesh has
such a large surface area. The surface area of a diffusion bonded
wire mesh can be as much as or more than five times greater than
the surface area of a microchannel type heat sink.
[0076] For all embodiments described herein, the cover 22 can be
fabricated from any suitable plastic, such as acetal (e.g.,
Delrin.TM. provided by DuPont), PVC, polyethylene, or
polypropylene. The cover 22 can also be fabricated from a metal,
such as copper. However, the heat exchange occurring in the chamber
24 appears to be so efficient and effective that the cover 22 need
not also be heat conductive. Even in embodiments having a metallic
cover there is little noticeable thermal change in the cover. Such
being the case, lighter-than-metal materials are preferred for
fabrication of the cover.
[0077] In the illustrated embodiments, when pumping 600 ml of fluid
less than about 0.5 psi of pressure is required, and preferably
about 0.4 psi or less. Thus, the heat sink assemblies operate in a
low pressure environment/application, i.e., below 3.0 psi.
[0078] In comparison to microchannels, diffusion bonded wire
channels provide more surface area over which fluid can pass.
Therefore, diffusion bonded wire channels transfer more heat into
the fluid traveling therethrough. Whereas microchannel devices have
a discrete and fairly low number of possible (unidirectional) fluid
paths, embodiments of the heat sink assemblies described herein
have myriad possible paths and combinations of paths through, e.g.,
the interstices of the wire mesh structure. Moreover, the
configurations of the paths and mesh nature of the wire mesh
structure, in addition to the impingement effect upon introduction
into the chamber, impart turbidity to the fluid. Accordingly,
essentially all of the fluid is exposed to the heat transfer metal
(e.g., either the thermal transfer plate or the wire mesh
structure) at some point in its travel. Further, as mentioned
previously, the number of tortuous channels formed by the diffusion
bonded wire mesh has low pressure drop.
[0079] While rectangular and/or square parallelepiped housings have
been illustrated for the example embodiments, other shape housings
are also contemplated. In fact, the housings can be of any
geometrical design so long as sized and configured to accommodate
the particular diffusion bonded wire mesh structure contained
therein. For example, other housing configurations include circular
or oval housings, and even housings of irregular shape. Moreover,
while the housings of the examples illustrated herein are
essentially two piece in having a base plate or thermal transfer
plate on one hand and a cover member on the other, the housing can
be otherwise formed.
[0080] While the invention has been described in connection with
what is presently considered to be the most practical and preferred
embodiments, it is to be understood that the invention is not to be
limited to the disclosed embodiments, but on the contrary, is
intended to cover various modifications and equivalent arrangements
included within the spirit and scope of the appended claims.
* * * * *