U.S. patent application number 13/405424 was filed with the patent office on 2012-12-27 for cooling device.
This patent application is currently assigned to TOSHIBA HOME TECHNOLOGY CORPORATION. Invention is credited to Osamu Honmura, Nobuo Ito, Nobuyuki Kojima, Naoto Sakuma.
Application Number | 20120325440 13/405424 |
Document ID | / |
Family ID | 47360722 |
Filed Date | 2012-12-27 |
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United States Patent
Application |
20120325440 |
Kind Code |
A1 |
Honmura; Osamu ; et
al. |
December 27, 2012 |
COOLING DEVICE
Abstract
There is provided a cooling device not affected by gravity by
exerting a strong capillary attraction to be hard to deteriorate in
transportation function. Unidirectionally-aligned copper fiber
assembly 8 is mounted, by a sintering process, on an inner wall of
a heat pipe 3 along the longitudinal direction of the heat pipe 3.
Therefore, by a strong capillary attraction caused by fine copper
fiber assembly 8, purified water can be transported without being
affected by gravity. A flow volume just enough for the purified
water to be prevented from drying out by its evaporation can be
maintained, thus making it hard for a function in the
transportation of the purified water to be deactivated. Further,
the unidirectionally-aligned copper fiber assembly 8 is mounted
along the longitudinal direction of heat pipe 3 and hence the
purified water smoothly flows in the longitudinal direction of heat
pipe 3.
Inventors: |
Honmura; Osamu; (Kamo,
JP) ; Kojima; Nobuyuki; (Kamo-shi, JP) ;
Sakuma; Naoto; (Kamo-shi, JP) ; Ito; Nobuo;
(Kamo-shi, JP) |
Assignee: |
TOSHIBA HOME TECHNOLOGY
CORPORATION
Kamo
JP
|
Family ID: |
47360722 |
Appl. No.: |
13/405424 |
Filed: |
February 27, 2012 |
Current U.S.
Class: |
165/104.26 |
Current CPC
Class: |
F28F 21/084 20130101;
F28D 15/0275 20130101; F28F 2255/18 20130101; F28D 15/046
20130101 |
Class at
Publication: |
165/104.26 |
International
Class: |
F28D 15/04 20060101
F28D015/04 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 27, 2011 |
JP |
2011-141551 |
Oct 19, 2011 |
JP |
2011-229706 |
Jan 13, 2012 |
JP |
2012-005509 |
Claims
1. A cooling device comprising: a pipe; and fine fibers mounted
inside said pipe for causing capillary attraction.
2. The cooling device according to claim 1, wherein a fiber
assembly is formed from said fibers aligned in an unidirectional
direction, said fiber assembly being mounted on an inner wall of
said pipe by a sintering process along a longitudinal direction of
said pipe.
3. The cooling device according to claim 1, further comprising
grooves formed in an inner wall of said pipe, wherein a fiber
assembly formed from said fibers is mounted so as to be attached
closely to insides of said grooves.
4. The cooling device according to claim 3, wherein said fiber
assembly formed from said fibers aligned in a unidirectional
direction is mounted by a sintering process along a longitudinal
direction of said pipe.
5. The cooling device according to claim 1, further comprising
grooves formed in an inner wall of said pipe, wherein a tube
produced by weaving said fibers into a mesh structure is mounted on
insides of said grooves.
6. The cooling device according to claim 1, further comprising
grooves formed in an inner wall of said pipe, wherein said fibers
are mounted on insides of said grooves.
7. The cooling device according to claim 6, wherein materials of
said pipe and said fibers are copper.
8. The cooling device according to claim 6, wherein a diameter of
said fibers is 20 .mu.m or more and is smaller than a width of said
groove.
9. The cooling device according to claim 1, further comprising:
grooves formed in an inner wall of said pipe; and a sheet produced
by sintering said fibers, wherein said sheet is attached closely to
protrusions of said grooves to sinter said fibers and said grooves
together.
10. The cooling device according to claim 1, further comprising:
grooves formed in an inner wall of said pipe; and an unwoven fabric
produced by laying linear fibers and web fibers on top of another
both of which are metallic and act as said fibers, said unwoven
fabric being mounted so as to be attached closely to protrusions of
said grooves.
11. The cooling device according to claim 1, further comprising:
grooves formed in an inner wall of said pipe; and a sheet produced
by joining linear fibers and web fibers together by sintering an
unwoven fabric produced by laying said linear fibers and said web
fibers on top of another both of which are metallic and act as said
fibers, said sheet being mounted so as to be attached closely to
protrusions of said grooves.
12. The cooling device according to claim 7, wherein a diameter of
said fibers is 20 .mu.m or more and is smaller than a width of said
groove.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a cooling device which is
suitable for cooling a heat source and enables a large amount of
heat transportation despite its compact size.
[0003] 2. Description of the Related Art
[0004] Heretofore, there has been known a cooling device utilizing
a capillary attraction effected by grooves and copper powders as a
result of forming the grooves on an inner wall of a pipe and
sintering the copper powders on the inner wall of the pipe to carry
a working fluid condensed in a heat dissipating section to a heat
receiving section (e.g., Japanese unexamined patent application
publication No. 2006-284020).
[0005] The conventional structure, however, functions poorly in
carrying a working fluid from the heat dissipating section to the
heat receiving section. In other words, the capillary attraction is
weak in a cooling device formed with the grooves on the inner wall
of the pipe, halting, in some cases, a function in the
transportation of the working fluid under the influence of gravity
depending on the installation attitude of a heat dissipating unit.
Further, in a device formed with copper powders on the inner wall
of the pipe by a sintering process, a flow volume of the working
fluid is insufficient and therefore the function in the
transportation of the working fluid is prone to deteriorate in some
cases. Hence, there is no other choice than to increase an amount
of the copper powders to obtain a sufficient flow volume of the
working fluid, incurring such a drawback as growths in size and
weight of device.
SUMMARY OF THE INVENTION
[0006] With a view to the problems described above, it is an object
of the present invention to provide a cooling device in which a
capillary attraction is so strong as to be unaffected by gravity,
and a function in the transportation of a working fluid is hard to
deteriorate by securing an enough flow volume of the working
fluid.
Means for Solving the Problem
[0007] A first aspect of the present invention is a cooling device
in which a working liquid accumulates at one end of a pipe by steam
condensation, while the working liquid evaporates at the other end
of the pipe. By a strong capillary attraction due to fine fibers,
the working fluid can be transported without being affected by
gravity and a flow volume just enough for the working fluid to be
prevented from drying out by its evaporation can be maintained,
making it hard for the function in the transportation of the
working fluid required for the cooling device to be
deactivated.
[0008] A second aspect of the present invention is a cooling device
in which a fiber body comprising unidirectionally-aligned fibers is
mounted along the longitudinal direction of the pipe and hence the
working fluid smoothly flows in the longitudinal direction of the
pipe, making it further hard for the function in the transportation
of the working fluid to be deactivated. Furthermore, the fiber body
is mounted on an inner wall of the pipe by sintering to maintain
the thermal conductivity between the pipe and the fiber body at a
favorable condition, permitting the thermal resistance of the pipe
to become excellent.
[0009] A third aspect of the present invention is a cooling device
in which the working fluid can be infallibly transported by a
strong capillary attraction exerted by the fine fibers in addition
to the capillary attraction of the grooves formed in the inner wall
of the pipe without being affected by gravity. Further, the flow
volume just enough for the working fluid to be prevented from
drying out by its evaporation can be sufficiently maintained,
making it further hard for the function in the transportation of
the working fluid required for the cooling device to be
deactivated. Furthermore, by covering the openings of the grooves
with the fibers, the capillary attraction is dramatically improved,
permitting enhancing the performance of the cooling device.
[0010] A fourth aspect of the present invention is a cooling device
in which the fiber body comprising the unidirectionally-aligned
fibers is mounted along the longitudinal direction of the pipe and
hence the working fluid smoothly flows in the longitudinal
direction of the pipe, making it furthermore hard for the function
in the transportation of the working fluid to be deactivated.
Further, the fiber body is mounted on the grooves formed in the
inner wall of the pipe by a sintering process to maintain the
thermal conductivity between the pipe and the fiber body at a
favorable condition, permitting the thermal resistance of the pipe
to become excellent.
[0011] A fifth aspect of the present invention is a cooling device
in which the working fluid can be infallibly transported by a
strong capillary attraction exerted by the fine fibers in addition
to the capillary attraction of the grooves formed in the inner wall
of the pipe without being affected by gravity. Further, the flow
volume just enough for the working fluid to be prevented from
drying out by its evaporation can be maintained, making it further
hard for the function in the transportation of the working fluid
required for the cooling device to be deactivated. Further, by
weaving fibers in a mesh structure, the fibers can be uniformly
mounted in a given position inside the pipe. Besides, since a tube
is formed by the fibers, the mounting workability on the pipe
becomes favorable, leading to low cost. Furthermore, by covering
the openings of the grooves with the fibers, the capillary
attraction is spectacularly improved, permitting the performance of
the cooling device to be improved.
[0012] A sixth aspect of the present invention is a cooling device
in which the working fluid can be infallibly transported by a
strong capillary attraction exerted by the fine fibers in addition
to the capillary attraction of the grooves formed in the inner wall
of the pipe without being affected by gravity. Further, the flow
volume just enough for the working fluid to be prevented from
drying out by its evaporation can be sufficiently maintained,
making it further hard for the function in the transportation of
the working fluid required for the cooling device to be
deactivated. Furthermore, by covering the openings of the grooves
with the fibers, the capillary attraction is spectacularly
improved, permitting the performance of the cooling device to be
improved.
[0013] A seventh aspect of the present invention is a cooling
device in which the material of the pipe formed with the grooves
and the material of the fibers are both copper to maximize the
capillary attraction, permitting the performance of the cooling
device to be further improved.
[0014] An eighth aspect of the present invention is a cooling
device in which by employing the fibers with a diameter not less
than 20 .mu.m, such a trouble with workability as breaking of the
fibers can be avoided. Besides, when the diameter of the fiber is
smaller than a width of the groove, a free exchange between a gas
phase and a liquid phase becomes possible, permitting the
performance of the cooling device to be further improved.
[0015] A ninth aspect of the present invention is a cooling device
in which the working fluid can be infallibly transported by a
strong capillary attraction exerted by the fine fibers in addition
to the capillary attraction of the grooves formed in the inner wall
of the pipe without being affected by gravity. Further, the flow
volume just enough for the working fluid to be prevented from
drying out by its evaporation can be maintained, making it further
hard for the function in the transportation of the working fluid
required for the cooling device to be deactivated. Furthermore,
after the sheet with which the fibers have been sintered in advance
is mounted in the pipe, the sheet is attached closely to the pipe
to sinter the sheet and the protrusions of the grooves together,
thereby permitting the capillary attraction to be maximally
improved and the thick of the sheet to be reduced to the utmost
extent. Moreover, by covering the openings of the grooves with the
fibers, the capillary attraction is spectacularly improved,
permitting the performance of the cooling device to be improved.
Moreover, the fiber body is mounted on the grooves formed in the
inner wall of the pipe by sintering to maintain the thermal
conductivity between the pipe and the fiber body at a favorable
condition, permitting the thermal resistance of the pipe to become
excellent.
[0016] A tenth aspect of the present invention is a cooling device
in which the working fluid can be infallibly transported by a
strong capillary attraction exerted by the fine fibers in addition
to the capillary attraction of the groove formed in the inner wall
of the pipe without being affected by gravity. Further, the flow
volume just enough for the working fluid to be prevented from
drying out by its evaporation can be maintained, making it further
hard for the function in the transportation of the working fluid
required for the cooling device to be deactivated. Furthermore, by
mounting an unwoven cloth, produced by laying linear fabrics and
web fabrics on top of another, inside the pipe, a closely-attached
condition between the unwoven cloth and the protrusions is
excellent and besides the openings of the grooves are covered with
the unwoven cloth with minute gaps. Therefore, the capillary
attraction can be spectacularly improved to enable the performance
of the cooling device to be improved and the pipe to be thinned due
to the thin unwoven cloth. Moreover, by mounting the unwoven cloth
on the grooves formed on the inside wall of the pipe by a sintering
process, the thermal conductivity between the pipe and the unwoven
cloth is maintained at a favorable condition, permitting the
thermal resistance of the pipe to become excellent.
[0017] An eleventh aspect of the present invention is a cooling
device in which the working fluid can be infallibly transported by
a strong capillary attraction exerted by the fine fibers in
addition to the capillary attraction of the groove formed in the
inner wall of the pipe without being affected by gravity. Further,
the flow volume just enough for the working fluid to be prevented
from drying out by its evaporation can be maintained, making it
further hard for the function in the transportation of the working
fluid required for the cooling device to be deactivated.
Furthermore, by mounting a sheet, produced by laying linear fabrics
and web fabrics on top of another, inside the pipe, the sheet and
the protrusions contact closely with each other and besides the
openings of the grooves are covered with the sheet with minute
gaps. Therefore, the capillary attraction can be spectacularly
improved to enable the performance of the cooling device to be
improved and the pipe to be thinned due to the thin sheet.
Moreover, by mounting the sheet on the grooves formed on the inside
wall of the pipe by a sintering process, the thermal conductivity
between the pipe and the sheet is maintained at a favorable
condition, permitting the thermal resistance of the pipe to become
excellent.
[0018] According to the first aspect of the present invention,
there can be provided the cooling device in which the capillary
attraction is so strong as to be unaffected by gravity so that it
is hard for the function in the transportation of the working fluid
to deteriorate owing to the enough flow volume of the working
fluid.
[0019] According to the second aspect of the present invention, the
function in the transportation of the working fluid can become
further hard to be deactivated and besides the thermal resistance
of the pipe is caused to become excellent.
[0020] According to the third aspect of the present invention,
there can be provided the cooling device in which the capillary
attraction is so strong as to be unaffected by gravity so that it
is hard for the function in the transportation of the working fluid
to deteriorate owing to the enough flow volume of the working
fluid. Further, the capillary attraction is spectacularly improved,
permitting the performance of the cooling device to be
improved.
[0021] According to the fourth aspect of the present invention, the
function in the transportation of the working fluid can become
further hard to be deactivated and besides the thermal resistance
of the pipe is caused to become excellent.
[0022] According to the fifth aspect of the present invention,
there can be provided the cooling device in which the capillary
attraction is so strong as to be unaffected by gravity so that it
is further hard for the function in the transportation of the
working fluid to deteriorate owing to the enough flow volume of the
working fluid. Further, there can be provided the cooling device
with the favorable workability of the mounting on the pipe and low
cost, and the capillary attraction is spectacularly improved,
permitting the performance of the cooling device to be
improved.
[0023] According to the sixth aspect of the present invention,
there can be provided the cooling device in which the capillary
attraction is so strong as to be unaffected by gravity so that it
is further hard for the function in the transportation of the
working fluid to deteriorate owing to the enough flow volume of the
working fluid. Further, the capillary attraction is spectacularly
improved, permitting the performance of the cooling device to be
improved.
[0024] According to the seventh aspect of the present invention,
the capillary attraction is maximized, permitting the performance
of the cooling device to be further improved.
[0025] According to the eighth aspect of the present invention, a
gas phase and a liquid phase can be freely exchanged therebetween,
permitting the performance of the cooling device to be further
improved.
[0026] According to the ninth aspect of the present invention,
there can be provided the cooling device in which the capillary
attraction is so strong as to be unaffected by gravity so that it
is further hard for the function in the transportation of the
working fluid to deteriorate owing to the enough flow volume of the
working fluid. Further, the capillary attraction is maximally
improved and the thick of the sheet is reduced to the utmost
extent. Furthermore, the capillary attraction is spectacularly
improved, permitting the performance of the cooling device to be
improved and besides the thermal resistance of the pipe is caused
to become excellent.
[0027] According to the tenth aspect of the present invention,
there can be provided the cooling device in which the capillary
attraction is so strong as to be unaffected by gravity so that it
is further hard for the function in the transportation of the
working fluid to deteriorate owing to the enough flow volume of the
working fluid. Further, the capillary attraction is spectacularly
improved, permitting the performance of the cooling device to be
improved. Furthermore, the pipe can be thinned and besides the
thermal resistance of the pipe is caused to become excellent.
[0028] According to the eleventh aspect of the present invention,
there can be provided the cooling device in which the capillary
attraction is so strong as to be unaffected by gravity so that it
is further hard for the function in the transportation of the
working fluid to deteriorate owing to the enough flow volume of the
working fluid. Further, the capillary attraction is spectacularly
improved, permitting the performance of the cooling device to be
improved. Furthermore, the pipe can be thinned and besides the
thermal resistance of the pipe is caused to become excellent.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] These objects and other objects and advantages of the
present invention will become more apparent upon reading of the
following detailed description and the accompanying drawings in
which:
[0030] FIG. 1 is an outline perspective view of a heat sink unit
acting as a cooling device common to each embodiment according to
the present invention.
[0031] FIG. 2 is an outline perspective view of a heat sink unit
acting as a cooling device shown from the other direction than FIG.
1.
[0032] FIG. 3 is an outline perspective view of a single body of a
heat pipe after applying a flattening process thereto, illustrating
a heat sink unit acting as a cooling device common to each
embodiment according to the present invention.
[0033] FIG. 4 is an outline perspective view of the single body of
the heat pipe before being subjected to the flattening process,
illustrating a heat sink unit acting as a cooling device common to
each embodiment according to the present invention.
[0034] FIG. 5 is a cross-sectional view on an A-A line in FIG. 4,
illustrating the first embodiment according to the present
invention.
[0035] FIG. 6 is an outline view of randomly directed copper
fibers, illustrating the first embodiment according to the present
invention.
[0036] FIG. 7 is an outline view of unidirectionally-aligned copper
fibers, illustrating the first embodiment according to the present
invention.
[0037] FIG. 8 is a cross-sectional view on A-A line in FIG. 4
showing another example of a cooling device, illustrating the first
embodiment according to the present invention.
[0038] FIG. 9 is a photograph of a partial cross-sectional view
after mounting and sintering copper fibers, illustrating the first
embodiment according to the present invention.
[0039] FIG. 10 is an enlarged photograph of FIG. 9, illustrating
the first embodiment according to the present invention.
[0040] FIG. 11 is a cross-sectional view on an A-A line in FIG. 4,
illustrating a second embodiment according to the present
invention.
[0041] FIG. 12 is a photograph of an actual heat pipe along a B-B
line in FIG. 11, illustrating the second embodiment according to
the present invention.
[0042] FIG. 13 is an enlarged photograph of FIG. 12, illustrating
the second embodiment according to the present invention.
[0043] FIG. 14 is a cross-sectional view on an A-A line in FIG. 4,
illustrating a third embodiment according to the present
invention.
[0044] FIG. 15 is a photograph of an outline perspective view of
the sheet comprising copper fibers, illustrating the third
embodiment according to the present invention.
[0045] FIG. 16 is an outline perspective view of the copper fibers,
illustrating the third embodiment according to the present
invention.
[0046] FIG. 17 is an outline view of a chief part in the process of
mounting the sheet, illustrating the third embodiment according to
the present invention.
[0047] FIG. 18 is a photograph of a cross section of a chief part
in the heat pipe, illustrating the third embodiment according to
the present invention.
[0048] FIG. 19 is a photograph of a cross section of the whole part
in the heat pipe, illustrating the third embodiment according to
the present invention.
[0049] FIG. 20 is a cross-sectional view on an A-A line in FIG. 4,
illustrating the fourth embodiment according to the present
invention.
[0050] FIG. 21 is a photograph of metal fibers wound around a piece
of cardboard, illustrating the fourth embodiment according to the
present invention.
[0051] FIG. 22 is an explanation drawing showing manufacturing
process of a nonwoven fabric, illustrating the fourth embodiment
according to the present invention.
[0052] FIG. 23 is a photograph of a sintered sheet after sintering
the nonwoven fabric, illustrating the fourth embodiment according
to the present invention.
[0053] FIG. 24A is a partially enlarged photograph showing surface
of a web fiber side of a sintered sheet, illustrating the fourth
embodiment according to the present invention.
[0054] FIG. 24B is a partially enlarged photograph showing surface
of a linear fiber side of a sintered sheet, illustrating the fourth
embodiment according to the present invention.
[0055] FIG. 25 is an outline view of a chief part in a process of
mounting the sintered sheet, illustrating the fourth embodiment
according to the present invention.
[0056] FIG. 26 is a photograph of a cross section of a chief part
in the heat pipe, illustrating the fourth embodiment according to
the present invention.
[0057] FIG. 27 is a photograph of a cross section of the whole part
in the heat pipe, illustrating the fourth embodiment according to
the present invention.
[0058] FIG. 28 is a photograph of a cross section of the whole part
in the heat pipe according to the conventional art by way of
comparison with FIG. 19 and FIG. 27.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0059] Hereunder, preferred embodiments of a cooling device
according to the present invention is described with a heat sink
unit for cooling a CPU or the like acting as a main heat
dissipating component of a personal computer taken as an
example.
[0060] FIG. 1 and FIG. 2 show an overall structure of the heat sink
unit, common to each embodiment, acting as a cooling device. In
these figures, numeral symbol 1 denotes a copper heat receiving
plate attached closely to the CPU (not shown), and numeral symbol 2
denotes heat dissipating fins made up by combining a plurality of
metallic plates for partitioning and forming a plurality of air
paths. The heat receiving plate 1 is coupled closely to a heat
receiving section 11 formed at the other end of a heat pipe 3
acting as a pipe, while the heat dissipating fins 2 are coupled
closely to a heat dissipating section 12 formed at one end of the
heat pipe 3. An air stream from a blower module, not shown, passes
through each air path in the heat dissipating section 12.
[0061] As shown in FIG. 3 and FIG. 4, the heat pipe 3 is formed
preferably from a material for a metallic pipe such as copper or
copper alloys which have high thermal conductivity. A hollow
cylindrical container 4 acts as a main body of the heat pipe 3 and
extends in its longitudinal direction. There are formed sealed
portions 5, 6 which are sealed by an appropriate means such as Tig
welding at both ends of the container 4, thus sealing up the
container 4 into a vacuum state. Further, in a state, shown in FIG.
4, before flattening and bending the heat pipe 3, the whole of the
heat pipe 3 is linear and is formed uniformly in outer shape and
thickness over entire length in the axial direction except for the
sealed portions 5, 6.
[0062] Now, when installing a heat sink unit including a heat pipe
3 in a low-profile electronic device such as a notebook-size
personal computer, an installation space is limited inside the
low-profile electronic device and therefore in a state, shown in
FIG. 3, subsequent to the flattening and bending processes, a bent
portion 21 is formed at an appropriate place of the container 4 as
necessary and besides there is formed a flattened portion 22 which
is produced by applying the flattening process to part of or the
whole of the container 4. A surface of the container 4 formed with
the flattened portion 22 is approximately flat. According to the
present embodiment, the flattened portion 22 is formed in at least
the heat receiving section 11 and heat dissipating section 12 of
the heat pipe 3, and then the heat receiving plate 1 and the heat
dissipating fins 2 are mounted on the flattened portion 22. Thus, a
closely-attached condition between the heat receiving plate 1 and
heat dissipating fins 2, and the heat pipe 3 is enhanced.
[0063] FIG. 5 to FIG. 10 show heat sink unit according to a first
embodiment according to the present invention. Specifically, FIG. 5
shows a cross-sectional view orthogonal to the longitudinal
direction of the heat pipe 3 shown in FIG. 4. In FIG. 5, the inner
wall of the container 4, shown here, is formed into a smooth curved
surface 16 without irregularities and the copper fiber assembly 8
acting as a fiber assembly with a wicked structure is hermetically
housed inside the heat pipe 3 so as to be attached closely to the
curved surface 16. The copper fiber assembly 8 is uniformly mounted
without a break in mid-course from one end of the heat pipe 3 to
the other end thereof. Then, inside the heat pipe 3, there are
provided a first flow path 17 formed inside the copper fiber
assembly 8 to transfer purified water (not shown), acting as a
working fluid condensed in the heat dissipating section 12, toward
the heat receiving section 11, and a second flow path 18 formed in
a region surrounded by the copper fiber assembly 8 to transfer
steam evaporated in the heat receiving section 11 toward the heat
dissipating section 12.
[0064] Each of FIG. 6 and FIG. 7 shows an outer appearance of a
single body of the copper fiber assembly 8. The copper fiber
assembly 8A shown in FIG. 6 is formed so that copper wires 24
acting as a plurality of fibers with a diameter ranging from a few
micrometers to several tens of micrometers are randomly entwined
with one another, while the copper fiber assembly 8B shown in FIG.
7 is formed so that copper wires 24 acting as a plurality of
comparatively longer fibers, with a diameter range from a few
micrometers to several tens of micrometers, than those of the
copper fiber assembly 8A are unidirectionally aligned in layers and
are entwined with one another. Then, either the randomly directed
copper fiber assembly 8A whose component copper wires 24 are
randomly arranged in direction or the uniformly directed copper
fiber assembly 8B whose component copper wires 24 are uniform in
direction is mounted in close contact with the inner wall of the
heat pipe 3, preferably by using a sintering process. Particularly,
in order to enhance the capillary attraction, the copper fiber
assembly 8B is mounted so that their component copper wires 24 are
aligned along the longitudinal direction of the heat pipe 3.
[0065] When manufacturing the heat pipe 3 as shown in FIG. 3,
firstly, the copper fiber assembly 8 is allowed to enter, from one
end (or the other end) of the heat pipe 3 whose both ends are
opened, the heat pipe 3 along the curved surface 16 formed on the
inner wall of the heat pipe 3. Thereafter, the one end of the heat
pipe 3 is throttled by a swaging process to be reduced in diameter
and then this diameter-reduced portion is sealed by Tig welding to
form the sealed portion 5. Further, the other end of the heat pipe
3 is also throttled by a swaging process to be reduced in diameter
and thereby prepare a nozzle for pouring purified water and
performing vacuuming. Next, after pouring purified water from the
nozzle into the heat pipe 3 and performing vacuuming, the nozzle is
sealed by Tig welding to form the sealed portion 6. At this moment,
the inside of the heat pipe 3 is hermetically blocked off from
external air, making it possible to obtain the heat pipe 3 in which
both the ends of the linear container 4 are sealed at the sealed
portions 5, 6, as shown in FIG. 4. Afterward, as described above,
an appropriate place of the container 4 is bent to form the bent
portion 21 and then part of or the whole of the container 4 is
flattened to form a flattened portion 22, thereby making it
possible to obtain a heat pipe 3 with a desired shape, as shown in
FIG. 3.
[0066] Next, the behavior of the above structure is described. In
using a notebook-size personal computer, when the heat from a CPU
transfers from the heat receiving plate 1 to the heat receiving
section 11, i.e., the other end of the heat pipe 3, the purified
water inside the heat receiving section 11 rises in temperature to
evaporate inside the heat pipe 3. The CPU is cooled by the heat of
evaporation and besides the steam pressure rises inside the heat
receiving section 11. Then, high-temperature steam flows through a
second flow path 18 to the heat dissipating section 12 of the one
end of the heat pipe 3. The heat dissipating fins 2 are thermally
connected with the heat dissipating section 12. Winds from a blower
module pass through the heat dissipating fins 2 and thereby the
steam that has reached the inside of the heat dissipating section
12 is cooled to condense, so that the condensation heat is
dissipated from the heat dissipating section 12. This action
continues until the temperature difference between the heat
receiving section 11 and the heat dissipating section 12 becomes
nonexistent. The purified water inside the heat pipe 3 flows from
the heat dissipating section 12 to the heat receiving section 11
through a first flow path 17 inside the copper fiber assembly 8, by
means of the capillary attraction caused by the copper fiber
assembly 8.
[0067] In this series of the cooling cycle, the purified water
accumulates by the steam condensation in the heat dissipating
section 12 cooled by heat dissipating fins 2, while the purified
water evaporates in the heat receiving section 11 receiving heat
from the CPU. By a strong capillary attraction caused by the cooper
fiber assembly 8 produced by entwining fine copper wires 24,
however, the purified water condensed in the heat dissipating
section 12 can be infallibly transported to the heat receiving
section 11 without being affected by gravity even if the heat sink
unit is placed at any attitude. Further, the purified water that
has reached the heat receiving section 11 can be maintained at a
flow volume just enough to be prevented from entirely drying out by
its evaporation. Therefore, the excellent heat pipe 3 can be
obtained whose function in the transportation of purified water is
hard to be deactivated.
[0068] In a manufacturing process of the heat pipe 3, in cases
where the copper fiber assembly 8 is sintered on the inner wall of
the heat pipe 3 in order to particularly enhance the
closely-attached condition between the heat pipe 3 and the copper
fiber assembly 8. Thus, when the purified water is transported from
the heat dissipating section 12 to the heat receiving section 11
through the first flow path 17 inside the copper fiber assembly 8,
heat transfers rapidly from the copper fiber assembly 8 to the heat
pipe 3 to enable the heat to be efficiently dissipated to the
outside of the heat pipe 3. As a result, the thermal conductivity
between the heat pipe 3 and the copper fiber assembly 8 can be
maintained at a favorable condition, permitting the thermal
resistance of the heat pipe 3 to become excellent.
[0069] Further, with respect to the wick structure inside the heat
pipe 3, when the copper fiber assembly 8B shown in FIG. 7 is
mounted on the inner wall of the heat pipe 3 so that the copper
wires 24 are mounted in one direction along the longitudinal
direction of the heat pipe 3, it becomes possible for the purified
water condensed in the heat dissipating section 12 to be smoothly
transported to the heat receiving section 11 along the longitudinal
direction of the heat pipe 3. As a result, the excellent heat pipe
3 can be obtained whose function in the transporting of the
purified water is further hard to be deactivated.
[0070] In addition, in order to attach the copper fiber assembly 8
closely to the inner wall of the heat pipe 3, instead of the
sintering process as described above, a method may be adopted in
which the copper fiber assembly 8 is pressed into the heat pipe 3,
or the copper fiber assembly 8 is pressed toward the inner wall of
the heat pipe 3 from the inside of the heat pipe 3 by utilizing a
pressing tool such as the resemblance of a coil spring and then
part of the copper fiber assembly 8 is welded to be joined to the
inner wall of the heat pipe 3.
[0071] Further, when mounting the copper fiber assembly 8 by a
sintering process, the copper fiber assembly 8 is inserted into the
heat pipe 3 and the copper fiber assembly 8 is heated at a
temperature range from a little less than 900.degree. C. to a
little less than 1,000.degree. C. in a vacuum or an atmosphere of
an inert gas with part of the copper fiber assembly 8 attached
closely to the inner wall of the heat pipe 3, thereby allowing the
copper fiber assembly 8 to be subjected to burning. Mounting the
copper fiber assembly 8 by the sintering process is performed
before a process of reducing each end of the heat pipe 3 in
diameter. For example, after reducing only one end of the heat pipe
3 in diameter, however, the copper fiber assembly 8 may be mounted
by the sintering process and thereafter the other end of the heat
pipe 3 may be reduced in diameter.
[0072] As described above, the copper wires 24 acting as fine
fibers for causing the capillary attraction are mounted inside the
heat pipe 3 acting as a pipe in the heatsink unit according to the
present embodiment.
[0073] In this case, the purified water acting as a working fluid
accumulates by the steam condensation at one end of the heat pipe
3, while the purified water evaporates at the other end of the heat
pipe 3. By a strong capillary attraction caused by the fine copper
wires 24, however, the purified water can be transported without
being affected by gravity and its flow volume just enough to be
prevented from drying out by its evaporation can be maintained.
Therefore, the function in the transportation of the purified water
by the heat sink unit acting as a cooling device is hard to be
deactivated.
[0074] Further, particularly according to the present embodiment,
the copper fiber assembly 8 acting as a fiber body comprising
unidirectionally-aligned copper wires 24 is mounted by a sintering
process along the longitudinal direction of the heat pipe 3 on the
inner wall of the heat pipe 3.
[0075] In this case, the copper fiber assembly 8 comprising
unidirectionally-aligned copper wires 24 is mounted along the
longitudinal direction of the heat pipe 3. Hence, the purified
water smoothly flows in the longitudinal direction of the heat pipe
3, making it further hard for the function in the transportation of
the purified water to be deactivated. Besides, by mounting the
copper fiber assembly 8 on the inner wall of the heat pipe 3 by a
sintering process, the thermal conductivity between the heat pipe 3
and the copper fiber assembly 8 is maintained at a favorable
condition, permitting the thermal resistance of the heat pipe 3 to
become excellent.
[0076] The inner wall of the heat pipe 3 shown in FIG. 5 is formed
into a smooth curved surface 16 without irregularities. As a
modified example, however, a plurality of grooves 19 is formed
uniformly over the whole circumference of the inner wall of the
heat pipe 3 and thereby these grooves 19 and the copper fiber
assembly 8 may be provided as a wick structure inside the heat pipe
3, as shown in FIG. 8. Each groove 19 is provided continuously
without a break in mid-course from one end of the heat pipe 3 to
the other end thereof to form a second flow path 18 together with
the inside of the copper fiber assembly 8. The copper fiber
assembly 8 is mounted so as to be attached closely to the insides
of the grooves 19, desirably by a sintering process. Also in this
modified example, either the randomly directed copper fiber
assembly 8A, shown in FIG. 6, whose component copper wires 24 are
random in direction or the uniformly directed copper fiber assembly
8B, shown in FIG. 7, whose component copper wires 24 are uniform in
direction, is mounted on the inner wall of the heat pipe 3. In the
case of employing the copper fiber assembly 8B, in order to enhance
its capillary attraction, the copper fiber assembly 8B is mounted
so that the copper wires 24 are aligned along the longitudinal
direction of the heat pipe 3.
[0077] The grooves 19 are preliminarily provided with both the ends
of the heat pipe 3 opened and hence a method for manufacturing the
heat pipe 3 has no difference from that described above. In the
completed heat pipe 3 shown in FIG. 4, in addition to a strong
capillary attraction caused by the copper fiber assembly 8, a
capillary attraction due to the grooves 19 also acts, permitting
the purified water condensed in the heat dissipating section 12 to
be unfailingly transported to the heat receiving section 11 along
the longitudinal direction of the heat pipe 3.
[0078] FIG. 9 and FIG. 10 show the conditions after the copper
fiber assembly 8B has been mounted inside the heat pipe 3 to be
sintered on the heat pipe 3. As evidenced by these figures, the
copper fiber assembly 8B is attached by a burning process closely
to a plurality of protrusions 20 which is formed between adjacent
grooves 19, 19 and protrudes from the inner wall of the heat pipe
3, enhancing the thermal conductivity from the copper fiber
assembly 8B to the heat pipe 3. Further, the copper fiber assembly
8B is mounted inside the heat pipe 3 so that no copper wire 24
enters the grooves 19 and hence the sufficient ability to transport
the purified water by the grooves 19 can be ensured.
[0079] As described above, according to the present modified
example, the grooves 19 are formed in the inner wall of the heat
pipe 3 and then the copper fiber assembly 8, acting as a fiber
assembly comprising fine copper wires 24 for causing a capillary
attraction, is mounted so as to be attached closely to the inside
of the grooves 19.
[0080] In this case, the purified water acting as a working fluid
accumulates by the steam condensation at one end of the heat pipe
3, while the purified water evaporates at the other end of the heat
pipe 3. By a strong capillary attraction caused by the fine copper
wires 24 in addition to the capillary attraction of the grooves 19
formed in the inner wall of the heat pipe 3, however, the purified
water can be unfailingly transported without being affected by
gravity. Further, the flow volume just enough for the purified
water to be prevented from drying out by its evaporation can be
sufficiently maintained, making it further hard for the function in
the transportation of the purified water required for the heat sink
unit to be deactivated. Furthermore, by covering the openings of
the grooves 19 with the copper wires 24, the capillary attraction
is spectacularly improved, permitting the performance of the heat
sink unit to be improved.
[0081] Furthermore, according to the present modified example, the
copper fiber assembly 8B comprising the unidirectionally-aligned
copper wires 24 may be mounted by a sintering process along the
longitudinal direction of the heat pipe 3.
[0082] In this case, the copper fiber assembly 8B comprising the
unidirectionally-aligned copper wires 24 is mounted on the heat
pipe 3 along the longitudinal direction of the heat pipe 3 and
therefore the purified water flows smoothly in the longitudinal
direction of the heat pipe 3, making it further hard for the
function in the transportation of the purified water to be
deactivated. Further, the copper fiber assembly 8B is mounted on
the grooves 19 formed in the inner wall of the heat pipe 3 by a
sintering process and thereby the thermal conductivity between the
heat pipe 3 and the copper fiber assembly 8 is maintained at a
favorable condition, enabling the thermal resistance of the heat
pipe 3 to become excellent.
[0083] Next, with reference to FIG. 1 to FIG. 4, and FIG. 11 to
FIG. 13, a heatsink unit is described according to a second
embodiment of the present invention. In addition, the common
numeral symbols are attached to parts the same as in the first
embodiment and the description thereof is omitted to avoid
overlapping as far as possible.
[0084] FIG. 11 shows a cross-sectional view orthogonal to the
longitudinal direction of the heat pipe 3 in FIG. 4. In FIG. 11, a
plurality of grooves 19 is uniformly formed over the whole
circumference of the inner wall of the heat pipe 3. At the same
time, copper fibers 28 acting as fibers are woven into a mesh
structure to form a tube body, thereby forming a tube 10. The tube
10 made up of the plurality of the copper fibers 28 is housed and
mounted in the heat pipe 3 so as to be attached closely to the
inside of the grooves 19.
[0085] The tube 10 and each groove 19 for making up a wick
structure are continuously provided without a break in mid-course
from one end of the heat pipe 3 to the other end thereof. Hence,
inside the heat pipe 3, there are provided a first flow path 17
formed in the tube 10 and each groove 19 to transfer the purified
water (not shown), acting as a working fluid, condensed in the heat
dissipating section 12 toward the heat receiving section 11 and a
second flow path 18 formed in a central region of the container 4
surrounded with the tube 10 to transfer steam evaporated in the
heat receiving section 11 toward the heat dissipating section
12.
[0086] According to the present embodiment, part of the copper
fibers 28 may be sintered on a plurality of the protrusions 20
formed between adjacent grooves 19, 19 to protrude from the inner
wall of the heat pipe 3. In this case, by the sintering of the
copper fibers 28, the copper fibers 28 are fixed closely to the
inner wall of the heat pipe 3 inside the grooves 19.
[0087] In order to manufacture the heat pipe 3 as shown in FIG. 3,
firstly, the above-described tube 10 comprising the copper fibers
28 is mounted from the one end (or the other end) of the heat pipe
3 whose both ends are opened so as to be attached closely to the
protrusions 20 on the inner sides of the grooves 19. Afterward, the
one end of the heat pipe 3 is throttled and reduced in diameter by
a swaging process and further the diameter-reduced portion is
sealed by Tig welding to form a sealed portion 5. Then, also the
other end of the heat pipe 3 is throttled by the swaging process to
be reduced in diameter, forming a nozzle for performing pouring
purified water and vacuuming. Next, purified water is poured from
the nozzle to an inside of the heat pipe 3 and vacuuming is
performed and then the nozzle is sealed by the Tig welding to form
the sealed portion 6. At this point, the inside of the heat pipe 3
is hermetically blocked off from external air, so that there can be
obtained the heat pipe 3 in which both the ends of the linear
container 4 are sealed at the sealed portions 5, 6, as shown in
FIG. 4. The inside state of the heat pipe 3 thus structured is
shown in FIG. 12 and FIG. 13. Thereafter, as described above, an
appropriate portion of the container 4 is bent to form a bent
portion 21 and further part of or the whole of the container 4 is
flattened to form a flattened portion 22, thereby allowing a heat
pipe with a desired shape shown in FIG. 3 to be obtained.
[0088] In a series of the above manufacturing process, the copper
fibers 28 are mounted closely on the insides of the grooves 19
formed in the inner wall of the heat pipe 3. The copper fibers 28
employed here are woven into a mesh structure in advance so that
the number of fibers is uniform to be hard to give rise to an
undulating form and are formed into a tube 10 kept in a hollow
state. Hence, the subsequent workability of mounting on the heat
pipe 3 is favorable and besides the copper fibers 28 becomes easy
to be arranged uniformly in a given position. In addition, one
elemental fiber of the copper fibers 28 is suitably several tens of
micrometers in diameter as far as workability is concerned.
[0089] Next is a description of the behavior of the above
structure. In using a notebook-size personal computer, when the
heat from the CPU transfers from the heat receiving plate 1 to the
heat receiving section 11 being the other end of the heat pipe 3,
the purified water inside the heat receiving section 11 rises in
temperature to evaporate inside the heat pipe 3. The CPU is cooled
by the heat of evaporation and the steam inside the heat receiving
section 11 rises in pressure. The high-temperature steam flows
through the second flow path 18 to the heat dissipation section 12
being one end of the heat pipe 3. The heat dissipating fins 2 are
connected thermally to the heat dissipating section 12 and winds
from the blower module pass through the heat dissipating fins 2 and
thereby the steam that has reached the inside of the heat
dissipation section 12 is cooled to condense, releasing
condensation heat from the heat dissipating section 12. This
behavior continues until a temperature difference between the heat
receiving section 11 and the heat dissipating section 12 becomes
nonexistent and at the same time the purified water accumulated in
the heat dissipating section 12 flows to the heat receiving section
11 through the first flow path 17 inside the grooves 19 and the
copper fibers 28, by the capillary attraction caused by the grooves
19 the copper fibers 28.
[0090] In this series of the cooling cycle, the purified water
accumulates by the condensation of the steam in the heat
dissipating section 12 cooled by the heat dissipating fins 2, while
the purified water evaporates in the heat receiving section 11
receiving the heat from the CPU. In order to maintain the function
as a heatsink unit, however, it is essential that the capillary
attraction described above is strong without being affected by
gravity so that the purified water condensed in the heat
dissipating section 12 can be unfailingly transferred to the heat
receiving section 11 even if the heat pipe 3 is placed at any
attitude and that the flow volume of the purified water, which has
reached the heat receiving section 11, just enough to be prevented
from entirely drying out by its evaporation is maintained.
[0091] Consequently, according to the present embodiment, by
closing the openings of the grooves 19 so as to be surrounded by
the fine copper fibers the capillary attraction inside the heat
pipe 3 is enhanced as well as maintaining the flow volume of the
purified water. Further, by weaving the copper fibers 28 into a
mesh structure, the copper fibers 28 can be arranged uniformly at a
given position inside the heat pipe 3. As a result, the function of
the heat pipe 3 becomes hard to be deactivated, leading to
excellent performance. Furthermore, the tube 10 of the copper
fibers 28 is employed, leading to good workability of mounting the
copper fibers 28 into the heat pipe 3 and low cost.
[0092] As described above, also heatsink unit according to the
present embodiment is mounted, inside the heat pipe 3 being a pipe,
with the copper fibers 28 acting as fine fibers for causing the
capillary attraction. Here, particularly, the grooves 19 are formed
in the inner wall of the heat pipe 3 and the hollow tube 10
produced by weaving the copper fibers 28 into a mesh structure is
mounted on the inside of the grooves 19.
[0093] In this case, by a strong capillary attraction caused by the
fine copper fibers 28 in addition to the capillary attraction of
the grooves 19 formed in the inner wall of the heat pipe 3, the
purified water can be infallibly transported without being affected
by gravity. Further, the flow volume just enough for the purified
water to be prevented from drying out by its evaporation can be
sufficiently maintained, making it further hard for the function in
the transportation of the purified water required for the heatsink
unit being the cooling device to be deactivated. Furthermore, by
weaving the copper fibers 28 into a mesh structure, the copper
fibers 28 can be uniformly arranged in a given position inside the
heat pipe 3. Moreover, the tube 10 is formed from the copper fibers
28, leading to the good workability of mounting the tube 10 in the
heat pipe 3, thereby resulting in low cost. In addition, by
covering the openings of the grooves 19 with the copper fibers 28,
the capillary attraction can be drastically improved, enabling the
performance of the heart sink unit to be enhanced.
[0094] Further, preferably, by sintering part of the copper wires
28 onto the inner wall of the heat pipe 3 inside the grooves 19,
heat is made easy to transfer from the heat pipe 3 to the copper
fibers 28, permitting the heat pipe 3 to be excellent in thermal
resistance.
[0095] Next is a description of a third embodiment of the present
invention with reference to FIG. 1 to FIG. 4, and FIG. 14 to FIG.
19. In addition, the same symbols are used for parts common to
those in the first and second embodiments and the description
thereof is omitted to avoid overlapping as far as possible.
[0096] In this embodiment, the inner structure of the heat pipe 3
is different from that in the second embodiment. Specifically, as
shown in FIG. 14, as a substitute for the tube 10 produced by
weaving the copper fibers 28, a sheet 30 is employed onto which the
copper fibers 28 are sintered. The copper fibers 28 employed here
are mounted on the inside of the container 4 of the heat pipe 3 so
as to be attached closely to the insides of the grooves 19.
[0097] In FIG. 15 and FIG. 16, both show a structure of a single
sheet 30 housed inside the heat pipe 3. The sheet 30 is produced by
processing a plurality of copper fibers 28 unidirectionally-aligned
in layers into a sheet using a sintering process. In order to
enhance the capillary attraction of the copper fibers 28, the sheet
30 is arranged so that the copper fibers 28 are unidirectionally
arranged along the longitudinal direction of the heat pipe 3.
[0098] In order to manufacture the heat pipe 3 as shown in FIG. 14,
firstly, the sheet 30 is rolled up into a tube to be mounted so
that the copper fibers 28 are unidirectionally arranged along the
longitudinal direction of the heat pipe 3 from one end (or the
other end) of the heat pipe 3 whose both ends are opened. A state
where a partial length of the sheet 30 has been inserted into the
inside of the heat pipe 3 is shown in FIG. 17. In FIG. 17, an
outline arrow indicates the inserting direction of the sheet 30.
Then, after the entire length of the sheet 30 has been inserted
into the inside of the heat pipe 3, the sheet 30 is attached
closely to the protrusions 20 inside the grooves 19 to sinter the
copper fibers 28 and the protrusions 20 of the heat pipe 3
together.
[0099] Thereafter, one end of the heat pipe 3 is throttled to be
reduced in diameter by applying a swaging process and then the
reduced-diameter portion is sealed by Tig welding, thus forming a
sealed portion 5. Besides, the other end of the heat pipe 3 is
throttled to be reduced in diameter by applying a swaging process
to prepare a nozzle through which purified water is poured and
vacuuming is performed. Next, the purified water is poured through
the nozzle into the inside of the heat pipe 3 and besides after
performing vacuuming, the nozzle is sealed by Tig welding, thus
forming the sealed portion 6. At this moment, the inside of the
heat pipe 3 is hermetically blocked off from external air to enable
the heat pipe 3 in which both the ends of the linear container 4
are sealed by the sealed portions 5, 6 to be obtained, as shown in
FIG. 4. FIG. 18 shows a state inside the heat pipe 3 at this
moment. Afterward, as described above, the bent portion 21 is
formed by bending an appropriate portion of the container 4 and
part of or the whole of the container 4 is flattened to form a
flattened portion 22, thereby making it possible to obtain the heat
pipe 3 with a desired shape shown in FIG. 3.
[0100] Next is a description of the behavior of the structure
described above. In using a notebook-size personal computer, when
heat from the CPU transfers from the heat receiving plate 1 to the
heat receiving section 11, being the other end of the heat pipe 3,
the purified water in the heat receiving section 11 rises in
temperature to evaporate inside the heat pipe 3. The CPU is cooled
by the heat of evaporation and steam pressure inside the heat
receiving section 11 rises, so that high-temperature steam flows
through the second flow path 18 to the heat dissipating section 12,
being one end of the heat pipe 3. The heat dissipating fins 2 are
connected thermally to the heat dissipating section 12. Winds from
the blower module pass through the heat dissipating fins 2 and
thereby the steam that has reached the inside of the heat
dissipating section 12 is cooled to condense. The condensation heat
is dissipated from the heat dissipating section 12. This action
continues until a temperature difference between the heat receiving
section 11 and the heat dissipating section 12 becomes non-existent
and the purified water accumulated in the heat dissipating section
12 flows to the heat receiving section 11 through the first flow
path 17 inside the grooves 19 and the copper fibers 28, by the
capillary attraction caused by the grooves 19 and the copper fibers
28.
[0101] In this series of the cooling cycle, the purified water
accumulates by steam condensation in the heat dissipating section
12 cooled by the heat dissipating fins 2, while the purified water
evaporates in the heat receiving section 11 receiving heat from the
CPU. However, in order that the purified water condensed in the
heat dissipating section 12 can be infallibly transported to the
heat receiving section 11 without being affected by gravity due to
the strong capillary attraction even if the heat pipe 3 is placed
at any attitude, and that the flow volume just enough for the
purified water that has reached the heat receiving section 11 to be
prevented from entirely drying out by its evaporation can be
maintained, according to the present embodiment, the grooves 19 are
formed in the inner wall of the heat pipe 3 and the copper fibers
28 are mounted closely on the protrusions 20 inside the grooves 19
and thereby the openings of the grooves 19 are covered with the
copper fibers 28, thus drastically improving the capillary
attraction caused in the grooves 19 inside the heat pipe 3. As a
result, the function of the heat pipe 3 is hard to be deactivated,
allowing the heat pipe 3 to be drastically improved and become
excellent in performance.
[0102] According to the present embodiment, as both the materials
of the heat pipe 3 and copper fibers 28, copper is selected to
enhance the capillary attraction inside the heat pipe 3. Further,
after being mounted on the container 4 of the heat pipe 3, the
sheet 30 on which the copper fibers 28 is sintered is attached
closely to the protrusions 20 of the heat pipe 3 to sinter the
copper fibers 28 and the protrusions 20 together, so that the
capillary attraction is maximized and the heat pipe 3 and the sheet
30 can be minimized in thickness.
[0103] In addition, in order to avoid such a problem in workability
as breaking of the copper fibers 28, the copper fibers 28 are
desirably 20 .mu.m or more in diameter and the upper limit of the
diameter is desirably smaller than a groove width of the opening
side of each groove 19. The grooves 19 are filled almost with
liquid-phase water, while the water inside the copper fibers 28 is
mainly in a gas-phase state. Then, in the operation of the heat
pipe 3, a free exchange between the liquid phase and the gas phase
is fundamental and hence it is crucial that the liquid-phase water
can transfer from the inside of the copper fibers 28 to the inside
of the grooves 19, while the gas-phase water of the grooves 19 can
transfer to the inside of the copper fibers 28. Consequently, it is
of importance that the fiber diameter of the copper fiber 28 is
smaller than the width of groove 19.
[0104] FIG. 19 is a photograph of a cross section of the heat pipe
3 after applying the flattening process according to the present
embodiment. In this photograph, a process of cutting the cross
section is poor to give some invisible parts of the grooves 19.
Actually, the grooves 19, however, are visible in the entire
circumference of the inside of the heat pipe 3.
[0105] As described above, also the heat sink unit according to the
present embodiment is mounted with the copper fibers 28 acting as
fine fibers for causing the capillary attraction inside the heat
pipe 3, being a pipe. Especially here, the grooves 19 are formed in
the inner wall of the heat pipe 3 and the copper fibers 28 are
mounted on the inside of the grooves 19.
[0106] As a result, by the strong capillary attraction caused by
the fine copper fibers 28 in addition to the capillary attraction
of the grooves 19 formed in the inner wall of the heat pipe 3, the
purified water can be infallibly transported without being affected
by gravity and the flow volume just enough for the purified water
to be prevented from drying out by its evaporation can be
sufficiently maintained. Hence, the function in the transportation
of the purified water required for the heat sink unit acting as a
cooling device becomes hard to be deactivated. Further, by covering
the openings of the grooves 19 with the copper fibers 28, the
capillary attraction can be drastically improved, enabling the
performance of the heart sink unit to be enhanced.
[0107] Furthermore, according to the present embodiment, the heat
pipe 3 and the copper fibers 28 are made of copper. In this case,
the materials of the heat pipe 3, in which the grooves 19 are
formed, and the copper fibers 28 are both copper and therefore the
capillary attraction is maximized, permitting the performance of
the heat sink unit to be enhanced.
[0108] According to the present embodiment, the copper fibers 28
are 20 .mu.m or more in elemental fiber diameter and this diameter
is smaller than the width of groove 19. In this case, by employing
the copper fibers 28 with 20 .mu.m or more in component fiber
diameter, such a problem in workability as breaking of the
component fibers of the copper fibers 28 can be avoided. Further,
the component fiber diameter of the copper fibers 28 is smaller
than the width of groove 19 and thereby the free exchange between
the gas phase and the liquid phase becomes possible between the
grooves 19 and the copper fibers 28, permitting the performance of
the heat sink unit to be further improved.
[0109] According to the present embodiment, the copper fibers 28
acting as the fine fibers for causing the capillary attraction are
mounted inside the heat pipe 3, being a pipe. Especially here, the
grooves 19 are formed in the inner wall of the heat pipe 3 and the
sheet 30 on which the copper fibers 28 are sintered is attached
closely to the protrusions 20, being projections of the grooves 19
of the heat pipe 3, to sinter the copper fibers 28 and the grooves
19 together.
[0110] As a result, by the strong capillary attraction caused by
the fine copper fibers 28 in addition to the capillary attraction
of the grooves 19 formed in the inner wall of the heat pipe 3, the
purified water can be infallibly transported without being affected
by gravity and a flow volume just enough for the purified water to
be prevented from drying out by its evaporation can be sufficiently
maintained. Hence, the function in the transportation of the
purified water required for the heat sink unit, being a cooling
device, is further hard to be deactivated. Further, the sheet 30 on
which the copper fibers 28 are sintered in advance is mounted on
the inside of the container 4 of the heat pipe 3, and thereafter
the sheet 30 is attached closely thereto to sinter the sheet 30 and
the protrusions 20 together, so that the capillary attraction is
maximized and the sheet 30 is minimized in thickness. Moreover, by
covering the openings of the grooves 19 with the copper fibers 28,
the capillary attraction can be drastically improved to enhance the
performance of the heat sink unit and besides by mounting the
copper fibers 28 on the grooves 19 formed in the inner wall of the
heat pipe 3 by a sintering process, the thermal conductivity
between the heat pipe 3 and the copper fibers 28 can be excellently
maintained, enabling the thermal resistance of the heat pipe 3 to
become excellent.
[0111] Further, according to the present embodiment, by mounting
the unidirectionally-aligned copper fibers 28 along the
longitudinal direction of the heat pipe 3 by a sintering process,
the purified water smoothly flows in the longitudinal direction of
the heat pipe 3, allowing the function in the transportation of the
purified water to be further hard to be deactivated.
[0112] Next is a description of a heat sink unit according to a
fourth embodiment of the present invention with reference to FIG. 1
to FIG. 4 and FIG. 20 to FIG. 27. In addition, common numeral
symbols are attached to the parts common to those in the first to
third embodiments and the description thereof is omitted to avoid
overlapping as far as possible.
[0113] FIG. 20 shows a cross-sectional view orthogonal to the
longitudinal direction of the heat pipe 3 in FIG. 4. In FIG. 20, a
plurality of grooves 19 is formed in the inner wall of the heat
pipe 3 uniformly over the entire circumference. At the same time,
according to the present embodiment, a nonwoven fabric 42 made up
of metallic fabric 41 such as copper fabric as fabrics or a
sintered sheet 43 obtained by sintering the nonwoven fabric 42 is
mounted on the inside of the heat pipe 3 to be housed therein so as
to be attached closely to the insides of the grooves 19.
[0114] The nonwoven fabric 42 or the sintered sheet 43 and each
groove 19, which have a wick structure, are continuously provided
without a break in mid-course from one end of the heat pipe 3 to
the other end thereof. Therefore, inside the heat pipe 3, there are
provided a first flow path 17 formed in the nonwoven fabric 42 or
the sintered sheet 43 and each groove 19 to transfer the purified
water (not shown), acting as a working fluid, condensed in the heat
dissipating section 12 to the heat receiving section 11, and a
second flow path 18 formed in the central region of the container 4
surrounded with the nonwoven fabric 42 or the sintered sheet 43 to
transfer the steam evaporated in the heat receiving section 11 to
the heat dissipating section 12.
[0115] FIG. 21 shows the metallic fibers 41 wound around a body to
be mounted thereon such as a cardboard piece 44. The metallic
fibers 41 are drawn from the cardboard 44 to form linear fibers 45
and web fibers 46, as shown in FIG. 22. By laying the linear fibers
45 and the web fibers 46 on top of another, the nonwoven fabric 42
is made which is capable of being mounted on the inside of the heat
pipe 3. In a general fiber sheet, warps and wefts are woven in a
net-like fashion. In the nonwoven fabric 42 according to the
present embodiment, however, the metallic fibers 41 are not woven.
The linear fibers 45 are long and approximately unidirectionally
and uniformly aligned. The web fibers 46 are shorter than the
linear fiber 45 and are randomly arranged. The linear fibers 45 and
the web fiber 46 are nearly evenly laid on top of another to
intertwine with one another, thereby forming the sheet-like
nonwoven fabric 42.
[0116] The linear fiber 45 and the web fiber 46 are both within 10
to 200 .mu.m in diameter. The smaller the diameter, the more
superior performance the heat pipe 3 exerts, while the larger the
diameter, the easier the processing of the metallic fiber 41,
thereby enabling the production costs to be reduced. Besides, the
linear fiber 45 is made as few dozens of meters in length in
producing the unwoven fabric 42. Subsequently, however, the unwoven
fabric 42 cut in accordance with the length (often on the order of
180 mm) of each heat pipe 3 is employed. The web fiber 46 is within
several mm to several tens of mm in length and its length is
different depending on the production method of the unwoven fabric
42.
[0117] The unwoven fabric 42 shown in FIG. 22 is cut into an
appropriate length and then can be mounted on the heat pipe 3. The
web fabric 46, however, is easy to disengage from the linear fabric
45 if the web fabric 46 is left as it is, and hence as shown in
FIG. 23, the unwoven fabric 42 may be sintered to join the linear
fibers 45 and the web fibers 46 together, thereby forming a
sintered sheet 43. FIG. 24A is a photograph of one side of the
sintered sheet 43 (the side of the web fiber 46), while FIG. 24B is
a photograph of the other side (the side of the linear fabric 45)
of the sintered sheet 43.
[0118] When manufacturing the heat pipe 3 shown in FIG. 3 using the
unwoven fabric 42 described above, firstly, from one end (or the
other end) of the heat pipe 3 whose both ends are opened, the
unwoven fabric 42, cut out into an appropriate size, is mounted so
as to be attached closely to as wide an area of the protrusions 20
as possible inside the grooves 19 formed in the inner wall of the
heat pipe 3. Here, the unwoven fabric 42 is rolled up into a tube
to be mounted on the inside of the heat pipe 3 so that the linear
fibers 45 are aligned along the longitudinal direction of the heat
pipe 3. In comparison with the cases where fine metallic wires are
mounted by a fixture tool or a net-like fabric sheet is mounted,
the unwoven fabric 42 is excellent in closely-attaching performance
to the protrusions 20, thus drastically improving the capillary
attraction and suiting to the thinning of the heat pipe 3.
[0119] Further, as described above, after the linear fibers 45 and
the web fibers 46 are laid on top of another to produce the unwoven
fabric 42, the unwoven fabric 42 is sintered and thereby the
sintered sheet 43 where the linear fibers 45 and the web fibers 46
are joined together can be produced. In order to manufacture the
heat pipe 3 as shown in FIG. 3 by using the sintered sheet 43,
firstly, from one end (or the other end) of the heat pipe 3 whose
both ends are opened, the sintered sheet 43, cut out into an
appropriate size, is mounted so as to be attached closely to as
wide an area of the protrusions 20 as possible inside the grooves
19 formed in the inner wall of the heat pipe 3. The state where the
sintered sheet 43 is partially mounted on the inside of the heat
pipe 3 is shown in FIG. 25. In the figure, an outline arrow
indicates the mounting direction of the sintered sheet 43. In this
case also, the sintered sheet 43 is rolled up into a tube to be
mounted on the inside of the heat pipe 3 so that the linear fibers
45 are aligned along the longitudinal direction of the heat pipe 3.
In comparison with the cases where metallic fine wires are mounted
by a fixture tool and a net-like fabric sheet is mounted, the
sintered sheet 43 obtained from the unwoven fabric 42 is excellent
in closely-attaching performance to the protrusions 20, thus
drastically improving the capillary attraction and suiting to the
thinning of the heat pipe 3.
[0120] In any case where the unwoven fabric 42 or the sintered
sheet 43 has been mounted on the heat pipe 3, afterward, one end of
the heat pipe 3 is throttled to be reduced in diameter by a swaging
process and further the diameter-reduced portion is sealed by Tig
welding to form the sealed portion 5. Then, the other end of the
heat pipe 3 is throttled to be reduced in diameter by the swaging
process to prepare a nozzle for pouring purified water and
performing vacuuming. Next, after pouring purified water from the
nozzle into the heat pipe 3 and performing vacuuming, the nozzle is
sealed by Tig welding to form the sealed portion 6. At this moment,
the inside of the heat pipe 3 is blocked off and is sealed
hermetically from external air, so that there can be obtained the
heat pipe 3 in which both the ends of the linear container 4 are
sealed at the sealed portions 5, 6, as shown in FIG. 4. The inside
state of the heat pipe 3 thus structured is shown in FIG. 26 and
FIG. 27. Thereafter, as described above, an appropriate portion of
the container 4 is bent to form a bent portion 21 and further part
of or the whole of the container 4 is flattened to form a flattened
portion 22, thereby allowing a heat pipe 3 with a desired shape
shown in FIG. 3 to be obtained.
[0121] In a series of the manufacturing process described above, in
the inner wall of the heat pipe 3, by mounting the unwoven fabric
42 (or the sintered sheet 43) so as to be attached closely to the
protrusions 20 formed between the grooves 19, 19, the opening of
each groove 19 is covered with the unwoven fabric 42 with fine
gaps, thereby drastically improving the capillary attraction caused
in the grooves 19. Then, in order to maximize the capillary
attraction, copper is selected for both materials of the heat pipe
3 and the unwoven fabric 42. Further, particularly, by employing
the sintered sheet 43 obtained by sintering the unwoven fabric 42,
the closely-attached condition of the sintered sheet 43 to the
protrusions 20 is further improved and the web fiber 46 is not
disengaged in its part of length in the inner wall of the heat pipe
3, thus making the workability of mounting the unwoven fabric 42
easy.
[0122] Further, after mounting the unwoven fabric 42 (or the
sintered sheet 43) on the inside of the heat pipe 3, for the
purpose of closely-attaching the unwoven fabric 42 to the
protrusions 20, the unwoven fabric 42 is outspread in the
peripheral direction of the heat pipe 3 by pushing the same and
then the unwoven fabric 42 and the protrusions 20 are joined
together by a sintering process. As a result, the capillary
attraction in the first flow path 17 can be enhanced to the maximum
extent possible and besides by subsequently performing a flattening
process to form the flattened portion 22, also the problem can be
avoided that an air gap results between the unwoven fabric 42 and
the protrusions 20. Further, in comparison with the conventional
sintered metallic type one produced by sintering copper powders on
the inner wall of the heat pipe 3, the unwoven fabric 42 can be
uniformly thinned and hence the thickness of the flattened portion
22 of the heat pipe 3 after being subjected to a flattening process
can be thinned.
[0123] When pressing the sintered sheet 43 (or the unwoven fabric
42) in the peripheral direction of the heat pipe 3, the sintered
sheet 43 is compressed and thereby the thin sintered sheet 43 made
up of high-density metallic fibers 41 enables the overall thickness
of the heat pipe 3 to be thinned, permitting the heat pipe 3 to be
made into an optimum form in use. In this case, the sintered sheet
43 exerts a higher closely-attached condition to the protrusions 20
of the heat pipe 3 than does a metallic net and has the strong
capillary attraction due to the high-density fibers, thereby
remarkably improving the performance of the heat pipe 3.
[0124] Further, the sintered sheet 43 inside the heat pipe 3 can be
formed thinner as compared to the conventional sintered metal (a
copper powder sintered product). The reason is that in the case of
the sintered metal, the copper powders are set in an air gap
between a mandrel mounted on the inside of the heat pipe 3 with
grooves 19 and the inner wall of the heat pipe 3, and after
sintering the copper powders, the mandrel must be drawn out and
therefore if the air gap is formed small, the copper powders
doesn't spread over the entire air gap, leading to impossibility of
thinning the thickness of the whole of the copper powders.
Actually, the unwoven fabric 42 after being mounted on the inside
of the heat pipe 3 is on the order of 0.2 to 0.3 mm in thickness.
As compared to the thickness (on the order of 0.5 to 0.6 mm) in the
case of sintering copper powders, the thickness of the sintered
sheet 43 can be equal to or smaller than half the thickness of
sintered copper powders. Furthermore, the unwoven fabric 42 and the
sintered sheet 43 according to the present embodiment are formed
into a sheet-like shape and hence a diameter of the metallic fiber
41 can be thinner to be capable of obtaining fine air gaps,
permitting the excellent heat pipe 3, as described above, with a
high capillary attraction to be obtained.
[0125] FIG. 27 is a photograph of a cross section of the heat pipe
3 after applying the flattening process thereto according to the
present embodiment. In the photograph, there are invisible parts of
the grooves 19 due to poor cut processing of the cross section.
Actually, the grooves 19, however, are visible in its entire
circumference inside the heat pipe 3. By way of comparison, the
cross section of the conventional heat pipe 3 on whose inner wall
of the container 4 the copper powders 60 are sintered is shown in
FIG. 28.
[0126] In the conventional heat pipe 3, it is hard to thinly and
uniformly provide the copper powders 60 and therefore also air gaps
are non-uniform. As a result, a water volume transported inside the
heat pipe 3 is insufficient to give rise to a high possibility of
falling into arrest of a function. Contrarily, in addition to the
tube 10 and the sheet 30 which are thinly and uniformly provided
with the copper fibers 28, all of the heat pipes 3 according to the
second to fourth embodiments include the unwoven fabric 42 and the
sintered sheet 43 which are made up of metallic fibers 41.
Therefore, the above problem is overcome to enable the performance
of the heat pipe 3 to be remarkably improved.
[0127] As described above, also the heat sink unit according to the
present embodiment is mounted with the metallic fibers 41 acting as
fine fibers for causing the capillary attraction, inside the heat
pipe 3, being a pipe. Especially here, the grooves 19 are formed in
the inner wall of the heat pipe 3 and the unwoven fabric 42, acting
as the above metallic fibers 41, produced by laying the metallic
linear fibers 45 and the web fibers 46 on top of another is mounted
on the protrusions 20, being projections of the grooves 19, so as
to be attached closely to the protrusions 20.
[0128] In this case, by the strong capillary attraction caused by
the fine metallic fibers 41 in addition to the capillary attraction
of the grooves 19 formed in the inner wall of the heat pipe 3, the
purified water can be infallibly transported without being affected
by gravity and besides a flow amount just enough for the purified
water to be prevented from drying out by its evaporation can be
maintained. Therefore, the function in the transportation of the
purified water required for the heatsink unit acting as a cooling
device is further hard to be deactivated. Further, the unwoven
fabric 42 produced by laying the linear fibers 45 and the web
fibers 46 on top of another is mounted on the inside of the heat
pipe 3 and thereby the closely-attached condition between the
unwoven fabric 42 and the protrusions 20 is good, and besides the
openings of the grooves 19 are covered with the unwoven fabric 42
with fine gaps. Hence, the capillary attraction is drastically
improved to enable the performance of the heat sink unit to be
enhanced and a low-profiled shape of the heat pipe 3 to be realized
due to the thin unwoven fabric 42. Besides, by mounting the unwoven
fabric 42 on the grooves 19 formed in the inner wall of the heat
pipe 3 by a sintering process, the thermal conductivity between the
heat pipe 3 and the unwoven fabric 42 can be excellently
maintained, enabling the thermal resistance of the heat pipe 3 to
become excellent.
[0129] The sintered sheet 43, acting as a sheet produced by
sintering the unwoven fabric 42 produced by laying the linear
fibers 45 and the web fibers 46 on top of another to join the both
the linear fibers 45 and the web fibers 46 together, may be mounted
on the protrusions 20, being projections of the grooves 19, so as
to be attached closely to the protrusions 20.
[0130] Also in this case, by the strong capillary attraction caused
by the fine metallic fibers 41 in addition to the capillary
attraction of the grooves 19 formed in the inner wall of the heat
pipe 3, the purified water can be infallibly transported without
being affected by gravity and besides the flow amount just enough
for the purified water to be prevented from drying out by its
evaporation can be sufficiently maintained. Therefore, the function
in the transportation of the purified water required for the heat
sink unit acting as a cooling device is further hard to be
deactivated. Further, the sintered sheet 43 obtained by sintering
the unwoven fabric 42 produced by laying the linear fibers 45 and
the web fibers 46 on top of another is mounted on the inside of the
heat pipe 3 and thereby the closely-attached condition between the
sintered sheet 43 and the protrusions 20 becomes much more
excellent, and besides the openings of the grooves 19 are covered
with the sintered sheet 43 with fine gaps. Hence, the capillary
attraction is drastically improved to enable the performance of the
heat sink unit to be enhanced and a low-profiled shape of the heat
pipe 3 to be realized due to the thin sintered sheet 43. Besides,
by mounting the sintered sheet 43 on the grooves 19 formed in the
inner wall of the heat pipe 3 by a sintering process, the thermal
conductivity between the heat pipe 3 and the sintered sheet 43 can
be excellently maintained, enabling the thermal resistance of the
heat pipe 3 to become excellent.
[0131] In addition, the present invention is not limited to the
above embodiments and various modifications are possible without
departing from the gist of the present invention. The cooling
device shown in each embodiment, e.g., can be incorporated in other
various devices requiring a cooling operation than a personal
computer. Further, a working fluid different from the purified
water can be housed and sealed inside the heat pipe 3. Furthermore,
in common with each embodiment, considering, as a condition for the
heat pipe 3, the large thermal conductivity for thermal
transportation, the corrosion resistance to sealed water,
hydrophilicity, the adequacy for a sintering process, and the
formation of the pipe and the fiber using the same material, copper
is the best for the materials of the heat pipe 3, the copper fiber
assembly 8, the tube 10, the sheet 30, the unwoven fabric 42, and
the sintered sheet 43. Other metals than copper such as aluminum,
SUS (stainless steel) or the like, however, are applicable
depending on the intended application as a cooling device. Further,
the diameters of a copper wire 24 and a metallic fiber 41 are
desirably smaller than the width of the groove 19 and the reason is
just as described in the third embodiment.
* * * * *