U.S. patent application number 10/936850 was filed with the patent office on 2005-05-12 for heat sink with heat pipes and method for manufacturing the same.
Invention is credited to Kawabata, Kenya, Ohno, Ryoji, Oomi, Masaru.
Application Number | 20050098300 10/936850 |
Document ID | / |
Family ID | 34549182 |
Filed Date | 2005-05-12 |
United States Patent
Application |
20050098300 |
Kind Code |
A1 |
Kawabata, Kenya ; et
al. |
May 12, 2005 |
Heat sink with heat pipes and method for manufacturing the same
Abstract
A heat sink including a base portion and a fin portion thermally
contacted with the base portion. The inside of the base portion has
at least one heat pipe, and a space (e.g., an air passage) formed
around part of the peripheral portion of the heat pipe. The base
portion is constructed of a first plate member that is contacted
with a heat source, and a second plate thermally contacted with the
fin portion. The heat pipe is placed between the first plate member
and the second plate and is thermally contacted with them.
Inventors: |
Kawabata, Kenya; (Tokyo,
JP) ; Oomi, Masaru; (Tokyo, JP) ; Ohno,
Ryoji; (Tokyo, JP) |
Correspondence
Address: |
CANTOR COLBURN, LLP
55 GRIFFIN ROAD SOUTH
BLOOMFIELD
CT
06002
|
Family ID: |
34549182 |
Appl. No.: |
10/936850 |
Filed: |
September 9, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60502821 |
Sep 12, 2003 |
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Current U.S.
Class: |
165/80.3 |
Current CPC
Class: |
F28F 3/02 20130101; F28D
15/0233 20130101; F28D 15/0275 20130101 |
Class at
Publication: |
165/080.3 |
International
Class: |
F25B 029/00 |
Claims
What is claimed is:
1. A heat sink comprising: a base portion having inside thereof at
least one heat pipe, and a space formed around part of a peripheral
portion of said heat pipe; and a fin portion thermally connected to
said base portion.
2. The heat sink as claimed in claim 1, wherein said base portion
comprises a first plate member thermally connected to a heat
source, and a second plate member thermally connected to said fin
portion; and said at least one heat pipe is placed between said
first plate member and said second plate member and is thermally
connected to said first plate member and said second plate
member.
3. The heat sink as claimed in claim 2, wherein said first plate
member comprises a U-shaped plate member including side wall
portions and a bottom surface portion; said second plate member
comprises a flat plate member being a top surface portion; and said
base portion comprises said top surface portion, said side wall
portions and said bottom surface portion.
4. The heat sink as claimed in claim 2, wherein said first plate
member comprises a flat plate member being a bottom surface
portion; said second plate member comprises a U-shaped plate member
including side wall portions and a top surface portion; and said
base portion comprises said top surface portion, said side wall
portions and said bottom surface portion.
5. The heat sink as claimed in claim 3 or 4, wherein said at least
one heat pipe comprises a flattened heat pipe, a top surface
portion of said flattened heat pipe being thermally connected to
said second plate member, and a bottom surface portion of said
flattened heat pipe being thermally connected to said first plate
member.
6. The heat sink as claimed in claim 3 or 4, wherein said space
comprises spaces defined by side surfaces of said heat pipe, said
side walls portions, said top surface portion and said bottom
surface portion of said base portion.
7. The heat sink as claimed in claim 3 or 4, wherein said space
comprises spaces between adjacent heat pipes and spaces defined by
side surfaces of said heat pipe, said side wall portions, said top
surface portion, and said bottom surface portion of said base
portion.
8. The heat sink as claimed in claim 7, wherein said heat pipe is
arranged so as to extend along a longitudinal direction of said fin
portion.
9. A heat sink comprising: a base portion having inside thereof at
least one heat pipe, a space formed around part of a peripheral
portion of said heat pipe, and a metal block; and a fin portion
thermally connected to said base portion.
10. The heat sink as claimed in claim 9, wherein said base portion
comprises a first plate member thermally connected to a heat
source, and a second plate member thermally connected to said fin
portion; and said at least one heat pipe and said metal block are
placed between said first plate member and said second plate
member, and are thermally connected to said first plate member and
said second plate member.
11. The heat sink as claimed in claim 10, wherein said first plate
member comprises a U-shaped plate member including side wall
portions and a bottom surface portion; said second plate comprises
a flat plate member being a top surface portion; and said base
portion comprises said top surface portion, said side wall
portions, and said bottom surface portion.
12. The heat sink as claimed in claim 10, wherein said first plate
member comprises a flat plate member being a bottom surface
portion; said second plate member comprises a U-shaped plate member
including side wall portions and a top surface portion; and said
base portion comprises said top surface portion, said side wall
portions and said bottom surface portion.
13. The heat sink as claimed in claim 10, wherein said metal block
is formed integrally with said first plate member.
14. The heat sink as claimed in claim 10, wherein said metal block
is arranged to extend across the entire length of said base
portion.
15. The heat sink as claimed in claim 10, wherein said metal block
is arranged only in a portion of said first plate member which is
connected to said heat source.
16. The heat sink as claimed in claim 10, wherein said metal block
is arranged between said heat pipes and is connected to part of
each heat pipe.
17. A method for manufacturing a heat sink, which comprising the
steps of: preparing a first plate member comprising a U-shaped
plate member including side wall portions and a bottom surface
portion, which is connected to a heat source, and joining at least
one heat pipe to the bottom surface portion of said U-shaped plate
member; preparing a second plate member comprising a flat plate
member, and joining a fin portion to one surface of said flat plate
member; and joining said first plate member with said heat pipe and
said second plate member with fin portion to fabricate a heat sink
comprising a base portion having inside thereof said at least one
heat pipe and a space formed around part of a peripheral portion of
said heat pipe, and said fin portion thermally connected to said
base portion.
18. The method as claimed in claim 17, wherein a metal block is
further joined to said bottom surface portion of said U-shaped
plate member.
19. The method as claimed in claim 17, wherein said base portion
and said heat pipe, as well as said base portion and said fin
portion, are simultaneously joined with solder.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a heat sink in which heat
pipes and a space (which functions as an air passages) are provided
inside of a base portion having a fin portion mounted thereon, and
a method for manufacturing the heat sink.
DESCRIPTION OF THE RELATED ART
[0002] A method of mounting fins on abase plate (which is a
heat-receiving portion) to dissipate the heat of a heat-generating
member is in general use as a heat sink for electronic equipment.
In a conventional heat sink consisting of a base plate and fins, an
extruded material of aluminum has been in use for many years, but
copper is now in wide use for the purpose of enhancing the ability
of releasing heat.
[0003] Copper is excellent in thermal conductivity, but when the
base plate of a heat sink is large or when a heat source is
arranged close to an end portion of the base plate, the effect of
spreading heat is not sufficient. In that case, the base plate is
provided with heat pipes or vapor chambers to enhance the
heat-spreading effect, whereby the performance to dissipate heat is
enhanced.
[0004] However, vapor chambers are costly and holes and screw holes
for mounting them have to be designed from the beginning, so that
design flexibility is reduced. On the other hand, when installing
heat pipes, holes or grooves must be formed in the base plate.
Thus, machine work is indispensable.
[0005] In addition, when the heat spreader is installed, the
thickness of the base plate is increased, thus the material cost is
increased and the increased weight requires a redesign for the
fixing method thereof, or the like.
[0006] Accordingly, one of the objects of the present invention is
to provide a heat sink that requires a reduced machine work and is
light in weight, low in cost, and high in performance.
SUMMARY OF THE INVENTION
[0007] The inventors have made various investigations and
experiments with respect to the disadvantages of the conventional
heat sinks and found the following facts. That is, if a heat pipe
is placed between a first plate member and a second plate, a
machine work, such as cutting, for mounting heat pipes becomes
unnecessary and the fabricating cost is reduced. In addition, since
a space is formed around the heat pipe, the weight of the base
portion is reduced and therefore a reduction in the weight of the
entire heat sink is achieved. Furthermore, since a portion of the
base portion near a heat source has an area that can exchange heat
with the surrounding air, it has been found that an enhancement in
the heat dissipating ability and an increase in the amount of the
surrounding air due to a reduction in passage resistance can be
expected.
[0008] The present invention has been made in view of the
above-described facts obtained from investigations and
experiments.
[0009] The first embodiment of the heat sink of the invention is
the heat sink comprising:
[0010] a base portion having inside thereof at least one heat pipe,
and a space formed around part of a peripheral portion of said heat
pipe; and
[0011] a fin portion thermally connected to said base portion.
[0012] In a second embodiment of the heat sink of the invention,
said base portion comprises a first plate member thermally
connected to a heat source, and a second plate member thermally
connected to said fin portion; and said at least one heat pipe is
placed between said first plate member and said second plate member
and is thermally connected to said first plate member and said
second plate member.
[0013] In a third embodiment of the heat sink of the invention,
said first plate member comprises a U-shaped plate member including
side wall portions and a bottom surface portion; said second plate
member comprises a flat plate member being a top surface portion;
and said base portion comprises said top surface portion, said side
wall portions and said bottom surface portion.
[0014] In a fourth embodiment of the heat sink of the invention,
said first plate member comprises a flat plate member being a
bottom surface portion; said second plate member comprises a
U-shaped plate member including side wall portions and a top
surface portion; and said base portion comprises said top surface
portion, said side wall portions and said bottom surface
portion.
[0015] In a fifth embodiment of the heat sink of the invention,
said at least one heat pipe comprises a flattened heat pipe, a top
surface portion of said flattened heat pipe being thermally
connected to said second plate member, and a bottom surface portion
of said flattened heat pipe being thermally connected to said first
plate member.
[0016] In a sixth embodiment of the heat sink of the invention,
said space comprises spaces defined by side surfaces of said heat
pipe, said side walls portions, said top surface portion and said
bottom surface portion of said base portion.
[0017] In a seventh embodiment of the heat sink of the invention,
said space comprises spaces between adjacent heat pipes and spaces
defined by side surfaces of said heat pipe, said side wall
portions, said top surface portion, and said bottom surface portion
of said base portion.
[0018] In an eighth embodiment of the heat sink of the invention,
said heat pipe is arranged so as to extend along a longitudinal
direction of said fin portion.
[0019] A ninth embodiment of the heat sink of the invention
comprises, a base portion having inside thereof at least one heat
pipe, a space formed around part of a peripheral portion of said
heat pipe, and a metal block; and a fin portion thermally connected
to said base portion.
[0020] In a tenth embodiment of the heat sink of the invention,
said base portion comprises a first plate member thermally
connected to a heat source, and a second plate member thermally
connected to said fin portion; and said at least one heat pipe and
said metal block are placed between said first plate member and
said second plate member, and are thermally connected to said first
plate member and said second plate member.
[0021] In an eleventh embodiment of the heat sink of the invention,
said first plate member comprises a U-shaped plate member including
side wall portions and a bottom surface portion; said second plate
comprises a flat plate member being a top surface portion; and said
base portion comprises said top surface portion, said side wall
portions, and said bottom surface portion.
[0022] In a twelfth embodiment of the heat sink of the invention,
said first plate member comprises a flat plate member being a
bottom surface portion; said second plate member comprises a
U-shaped plate member including side wall portions and a top
surface portion; and said base portion comprises said top surface
portion, said side wall portions and said bottom surface
portion.
[0023] In a thirteenth embodiment of the heat sink of the
invention, said metal block is formed integrally with said first
plate member.
[0024] In a fourteenth embodiment of the heat sink of the
invention, said metal block is arranged to extend across the entire
length of said base portion.
[0025] In a fifteenth embodiment of the heat sink of the invention,
said metal block is arranged only in a portion of said first plate
member which is connected to said heat source.
[0026] In a sixteenth embodiment of the heat sink of the invention,
said metal block is arranged between said heat pipes and is
connected to part of each heat pipe.
[0027] A first embodiment of a method for manufacturing a heat sink
of the invention comprises the steps of:
[0028] preparing a first plate member comprising a U-shaped plate
member including side wall portions and a bottom surface portion,
which is connected to a heat source, and joining at least one heat
pipe to the bottom surface portion of said U-shaped plate
member;
[0029] preparing a second plate member comprising a flat plate
member, and joining a fin portion to one surface of said flat plate
member; and
[0030] joining said first plate member with said heat pipe and said
second plate member with fin portion to fabricate a heat sink
comprising a base portion having inside thereof said at least one
heat pipe and a space formed around part of a peripheral portion of
said heat pipe, and said fin portion thermally connected to said
base portion.
[0031] In a second embodiment of the method of the invention, a
metal block is further joined to said bottom surface portion of
said U-shaped plate member.
[0032] In a third embodiment of the method of the invention, said
base portion and said heat pipe, as well as said base portion and
said fin portion, are simultaneously joined with solder.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] The present invention will be described in further detail
with reference to the accompanying drawings wherein:
[0034] FIG. 1 is a perspective view showing a heat sink with heat
pipes constructed in accordance with one preferred form of the
present invention;
[0035] FIG. 2 is a plan view of the heat sink shown in FIG. 1;
[0036] FIG. 3 is a diagram used to explain the heat pipes arranged
within the base portion of the heat sink shown in FIG. 1;
[0037] FIG. 4 is an exploded perspective view of the second plate
joined with the fin portion and the first plate member joined with
the heat pipes, constituting the heat sink shown in FIG. 1;
[0038] FIG. 5 is a perspective view showing a heat sink with heat
pipes constructed in accordance with another preferred form of the
present invention;
[0039] FIG. 6 is a part-perspective view used to explain the
positions where the metal block and the heat pipes are joined to
the first plate member;
[0040] FIG. 7 is a plan view used to explain the metal block and
heat pipes arranged within the base portion;
[0041] FIG. 8 is a plan view used to explain a metal block arranged
only in a portion of the first plate member that is contacted with
a heat source heat;
[0042] FIG. 9 is a plan view showing another arrangement of heat
pipes;
[0043] FIG. 10 is a side view of a heat sink equipped with heat
pipes arranged as shown in FIG. 9;
[0044] FIG. 11 is a plan view showing another arrangement of a
copper solid and heat pipes;
[0045] FIG. 12 is a side view of a heat sink equipped with a copper
solid and heat pipes arranged as shown in FIG. 11;
[0046] FIG. 13 is a plan view showing a third arrangement of heat
pipes;
[0047] FIG. 14 is a sectional view taken along line A-A' of FIG.
13;
[0048] FIG. 15 is a plan view showing a fourth arrangement of heat
pipes;
[0049] FIG. 16 is a sectional view taken along line A-A' of FIG.
15; and
[0050] FIG. 17 is a sectional view taken along line B-B' of FIG.
15.
DETAILED DESCRIPTION OF THE INVENTION
[0051] A heat sink and a heat-sink fabricating method according to
the present invention will hereinafter be described in detail with
reference to the drawings.
[0052] A first heat sink of the present invention includes a base
portion and a fin portion thermally contacted with the base
portion. The inside of the base portion has at least one heat pipe,
and a space (e.g., an air passage) formed around part of the
peripheral portion of the heat pipe. The base portion is made up of
a first plate member that is contacted with a heat source, and a
second plate member thermally contacted with the fin portion. The
aforementioned at least one heat pipe is placed between the first
plate member and the second plate member and is thermally contacted
with the first plate member and the second plate member.
[0053] The first plate member consists of a U-shaped plate having
side wall portions and a bottom surface portion formed between the
side wall portions. The second plate member consists of a flat
plate member having a top surface portion. The base portion is
constructed of the top surface portion, the side wall portions, and
the bottom surface portion. Note that the second plate member may
consist of a U-shaped plate member having side wall portions and a
bottom surface portion formed between the side wall portions. Also,
the first plate member may consist of a flat plate member having a
bottom surface portion. When a heat source is small, or when it is
positioned at an end portion of a heat sink, it is necessary to
spread heat over the entire heat sink and enhance the heat
dissipating efficiency of the fin portion joined to the base
portion. Generally, heat pipes or vapor chambers are employed in a
heat sink. In the case of heat pipe, the aforementioned
conventional base portion is provided with grooves or holes, and
heat pipes in the grooves or holes are fixed with solder.
[0054] In the heat sink of the present invention, the heat pipe is
placed between the first plate member and the second plate member,
as described above. Therefore, a machine work, such as cutting, for
mounting the heat pipe becomes unnecessary and the fabricating cost
is reduced. In addition, since a space is formed around the heat
pipe, the weight of the base portion is reduced and therefore a
reduction in the weight of the entire heat sink is achieved.
Furthermore, since a portion of the base portion near the heat
source has an area that can exchange heat with the surrounding air,
an enhancement in the heat dissipating ability and an increase in
the amount of the surrounding air due to a reduction in passage
resistance can be expected.
[0055] Referring to FIG. 1, there is shown a heat sink constructed
in accordance with one preferred form of the present invention. As
shown in the figure, the inside of a base portion 8 has at least
one heat pipe 5, and air passages 6 formed around part of the
peripheral portion of the heat pipe 5. The base portion 8 is
thermally contacted with a fin portion 3. This base portion 8 is
constructed of a first plate member 4 that is thermally contacted
with a heat source (not shown), and a second plate member 2
thermally contacted with the fin portion 3. At least one heat pipe
5 is placed between the first plate member 4 and the second plate
member 2 and is thermally contacted with the first plate member and
the second plate member.
[0056] The first plate member 4 consists of a U-shaped plate member
having side wall portions 9 and a bottom surface portion 10 formed
between the side wall portions 9. The second plate member 2
consists of a flat plate member having a top surface portion 2.
Thus, the base portion 8 consists of the top surface portion 2,
side wall portions 9, and bottom surface portion 10.
[0057] The heat pipe 5 is formed by compressing a round type heat
pipe to be a flat heat pipe (hereinafter referred to as a
"flattened heat pipe", whereby the contact surface between the top
surface of the heat pipe and the second plate member 2 and the
contact surface between the bottom surface of the heat pipe and the
first plate members 4 are made larger. In FIG. 1, three flattened
heat pipes 5 are arranged within the base portion 8. Spaces as air
passages 6 are provided in a portion defined by the top surface
portion, the bottom surface portion, the side wall portion 9 of the
first plate member 4 and the heat pipe 5, and in a portion defined
by the top surface portion, the bottom surface portion, adjacent
heat pipes 5, respectively. The air passage 6 extends across the
entire length of the base portion 8 along the longitudinal
direction of the fin portion 3. When performing forced-air cooling
with a fan, etc., the surrounding air flows through not only the
spaces between the fins of the fin portion 3 but also the air
passages 6, so the heat dissipating efficiency is enhanced.
[0058] As set forth above, at least one heat pipe 5 is constructed
of a flattened heat pipe. The top surface portion of the flattened
heat pipe thermally contacts the second plate member 2, while the
bottom surface portion thermally contacts the first plate member
4.
[0059] By adjusting the thickness of the heat pipe 5 and the
thickness of the first and second plate members 4 and 2, the base
portion 8 can be made thinner.
[0060] The fin portion 3 may be joined to one surface of the base
portion 8 with solder, etc. The fin portion 3 may also be formed
integrally with the base portion 8 as one unit. Furthermore, both
sides of each fin which is inserted in the groove formed in the
base portion 8 may be mechanically crimped and fixed to the base
portion.
[0061] FIG. 2 shows a plan view of the heat sink 1 of the present
invention. As shown in the figure, the fin portion 3 is formed on
one surface of the base portion 8. The fin pitch of the fin portion
3 is made small in order to enhance the effect of releasing heat.
Although not shown, a heat source is arranged on the left end
portion of the heat sink shown in FIG. 2. The first plate member 4
on which a heat source is arranged is thermally contacted with the
heat pipes 5, so heat is transferred along the longitudinal
direction of the base portion 8 by the heat pipes 5 and is
dissipated through the fin portion 3 joined to the second plate
member 2. As set forth above, heat from a heat source arranged on
the bottom surface of the first plate member 4 is uniformly spread
over the entire base portion 8 by the heat pipes 5 and is then
dissipated from the fin portion 3 through the surrounding air.
[0062] As shown in FIG. 2, fins are cut out at positions where the
fin portion 3 is fixed to the heat sink 1, and fixing members are
installed. The heat sink 1 of the present invention is capable of
significantly enhancing the heat dissipating efficiency when a heat
source is arranged on one end portion of the base portion 8.
[0063] FIG. 3 is a diagram used to explain the heat pipes 5
arranged within the base portion of the heat sink. As shown in the
figure, the inside of the base portion has at least one flattened
heat pipe 5. In the example shown in. FIG. 3, three heat pipes 5
are arranged within the base portion. That is, the flattened heat
pipes 5 are placed between the bottom surface portion of the
U-shaped first plate member (where a heat source is placed) and the
top surface portion of the second plate member (joined with the fin
portion) and are contacted with the bottom surface portion and top
surface portion of the first and second plate members through the
flattened wide top and bottom surface portions of the heat pipes 5.
Although the arrangement of the heat pipes 5 is determined in
dependence on the size and position of a heat source, they are
arranged across the entire length of the base portion 8 along the
longitudinal direction of the base portion 8. Note that the heat
pipes 5 do not always need to be arranged across the entire length
of the base portion 8. They may be arranged across approximately
the entire length, or across a longitudinal length that can obtain
the effect of spreading heat over the entire base portion.
[0064] Between the side wall portion of the first plate member and
a side surface of the heat pipe 5 and between adjacent heat pipes
5, there are provided spaces for air passages 6. By installing a
fan for forced-air cooling at one end portion of the base portion,
the surrounding air is forcibly passed through the air passages 6,
so that the heat dissipating efficiency is increased.
[0065] The heat sink with heat pipes of the present invention is
fabricated as follows:
[0066] That is, a U-shaped plate member, which is contacted with a
heat source, equipped with side wall portions and a bottom surface
portion is prepared and then a first plate member is prepared by
joining at least one heat pipe to the bottom surface portion of the
U-shaped plate member. Next, a flat plate member is prepared and a
second plate member is prepared by joining a heat dissipating fin
portion to one surface of the flat plate member. And the first
plate member and the second plate member are joined together to
fabricate a heat sink, which includes a base portion having in an
inside thereof at least one heat pipe and an air passage formed
around part of the peripheral portion of the heat pipe, and a fin
portion thermally contacted with the base portion. The fabrication
method will be described along with the heat sink of the present
invention.
[0067] FIG. 4 shows the second plate member 2 joined with the fin
portion 3 and the first plate member 4 joined with the heat pipes
5, constituting the heat sink 1 of the present invention.
[0068] As shown in the upper portion of FIG. 4, a flat plate member
is first prepared. Then, the second plate member 2 is prepared by
joining the heat dissipating fin portion 3 on one surface of the
flat plate member. Next, as shown in the lower portion of FIG. 4, a
U-shaped plate member, which is contacted with a heat source,
equipped with side wall portions 9 and a bottom surface portion 10
is prepared and the first plate member 4 is prepared by joining
heat pipes 5 to the bottom surface portion of the U-shaped plate
member.
[0069] Next, if the first plate member 4 joined with the heat pipes
5 and the second plate member 2 joined with the fin portion 3, thus
prepared, are joined together, a heat sink is fabricated which
consists of a base portion having in the inside at least one heat
pipe and air passages formed around part of the peripheral portion
of the heat pipe, and a fin portion thermally contacted with the
base portion.
[0070] As described above, in the heat-sink fabricating method of
the present invention, the heat pipes 5 are placed between the
first and second plate members 4 and 2 and are thermally contacted
with them through wide areas. Therefore, grooves or holes for
mounting heat pipes are not needed, as are needed in prior art.
Thus, the fabricating cost can be reduced and the heat sink 1 can
be easily fabricated.
[0071] Referring to FIG. 5, there is shown a second heat sink
constructed in accordance with a second preferred form of the
present invention.
[0072] The second heat sink of the present invention includes a
base portion, and a fin portion thermally contacted with the base
portion. The inside of the base portion has at least one heat pipe,
air passages formed around part of the peripheral portion of the
heat pipe, and a metal block. The base portion consists of a first
plate member that is contacted with a heat source, and a second
plate member thermally contacted with the fin portion. At least one
heat pipe and the metal block are placed between the first and
second plate members and are thermally contacted with them.
[0073] As shown in FIG. 5, the inside of a base portion 18 has at
least one heat pipe 15, air passages 26 formed around part of the
peripheral portion of the heat pipe 15, and a metal block 17. The
top surface 12 of the base portion 18 is thermally contacted with a
fin portion 13. The base portion 18 consists of a first plate
member 14 that is contacted with a heat source, and a second plate
member 12 thermally contacted with the fin portion 13. At least one
heat pipe 15 and metal block 17 are placed between the first and
second plate members 14 and 12 and are thermally contacted with
them.
[0074] The first plate member 14 is constructed of a U-shaped plate
member having side wall portions 19 and a bottom surface portion 20
formed between the side wall portions 19. The second plate member
12 is constructed of a flat plate member having a top surface
portion 12. Thus, the base portion 18 is made up of the top surface
portion 12, side wall portions 19, and bottom surface portion
20.
[0075] In the heat sink 10 shown in FIG. 5, the metal block 17 is
arranged at approximately the central portion of the first plate
member 14, and the flattened heat pipes 15 are arranged on both
sides of the metal block 17. Between the side wall portion 19 of
the first plate member 14 and the heat pipe 15, there is formed an
air passage 16.
[0076] FIG. 6 shows how the metal block and the heat pipes are
arranged on the first plate member. As shown in the figure, the
rectangular metal block 17 is arranged at approximately the central
portion of the bottom surface portion of the first plate member 14.
As shown by a dotted line, the flattened heat pipes 15 contact the
metal block 17 and are provided on both sides of the metal block
17. The positions of the metal block 17 and heat pipes 15 are not
limited to those shown in FIG. 6. In dependence on the size and
position of a heat source, the positions of the metal block 17 and
heat pipes 15 may be changed in order to enhance the heat
dissipating efficiency.
[0077] The metal block 17 is able to prevent the heat pipes 15 from
drying out when the calorific value of a heat source is
particularly great. By contacting the heat pipe 15 with the first
plate member 14 (which is contacted with a heat source) and the
metal block 17, heat is absorbed by the wide area of the heat pipe
15 through the first plate member 14 and the side wall surface of
metal block 17, and a large amount of heat is transferred to the
other end of the heat pipe 15 by the phase change of the working
fluid between the vapor phase and the fluid phase.
[0078] FIG. 7 shows how the metal block 17 and heat pipes 15 are
arranged within the base portion 18. As shown in the figure, at
least one flattened heat pipe 15 and metal block 17 are arranged in
the inside of the base portion 18. In the example of FIG. 7, the
metal block 17 is arranged at the central portion of the inside of
the base portion 18, and the heat pipes 15 are arranged both sides
of the metal block 17. That is, the metal block 17 and flattened
heat pipes 15 are placed between the bottom surface portion 20 of
the U-shaped first plate member 14 (which is contacted by a heat
source) and the top surface portion of the second plate member 12
(joined with the fin portion) and are thermally contacted with the
first and second plate members 14 and 12 through the wide areas
thereof. In this way, the metal block 17 and flattened heat pipes
15 are arranged in the inside of the base portion 18.
[0079] Although the heat pipe 15 and metal block 17 are arranged in
dependence on the size and position of a heat source, they are
arranged across the entire length of the base portion 18 along the
longitudinal direction of the base portion 18. In addition, between
the side wall portion of the first plate member 14 and the side
surface of the heat pipe 15, there is provided a space for air
passage. By installing a fan for forced-air cooling at one end
portion of the base portion 18, the surrounding air can be forcibly
passed through the air passages 16, so that the heat dissipating
efficiency is enhanced.
[0080] The above-described metal block 17 may be formed integrally
with the first plate member 14 instead of being joined to the first
plate member 14. In the above-described heat sinks 1 and 10 of the
present invention, while the metal block 17 is arranged across the
entire length of the base portion 18, the metal block 17 may be
arranged only in a portion of the first plate member 14 which is
contacted with a heat source.
[0081] FIG. 8 shows the case where a metal block is arranged only
in a portion of the first plate member that is contacted with a
heat source heat. As shown in the figure, the metal block 17 is
arranged only in a portion of the first plate member 12 that is
contacted with a heat source heat. The heat pipes 15 are provided
along the longitudinal direction across the entire length of the
base portion 18.
[0082] FIG. 9 shows another arrangement of heat pipes. As shown in
the figure, three heat pipes 5 are arranged close to each other at
one end of a first plate member 4 where a heat source 30 is
arranged. The spacing between the heat pipes 5 becomes wider toward
the other end of the first plate member 4. As with the
aforementioned examples, spaces (e.g., air passages) are formed
around the peripheral portion of the heat pipe 5.
[0083] FIG. 10 shows a heat sink equipped with heat pipes arranged
as shown in FIG. 9. As shown in FIG. 10, three heat pipes 5 are
arranged close to each other at one end of a first plate member 4
where a heat source 30 is arranged. A fin portion 3 is mounted on
the top surface of a second plate member.
[0084] FIG. 11 shows another arrangement of a copper solid and heat
pipes. In this example, a heat sink includes a copper solid and a
base portion, arranged in parallel with the copper solid, which has
spaces formed around a heat pipe. As shown in FIG. 11, the copper
solid 21 is formed integrally with a first plate member 4. A heat
source 30 is arranged so it thermally contacts the copper solid 21
and the first plate member 4. That is, a portion of the copper
solid 21 is arranged so it thermally contacts the heat source 30.
Similarly, some of three heat pipes 3 are arranged so they
thermally contact the heat source 30 through the first plate member
4. In this example, the three heat pipes 5 are arranged close to
each other at the central portion, and the spacing between the heat
pipes 5 is gradually increased from the central portion toward both
end portions of the first plate member 4.
[0085] FIG. 12 shows a heat sink having a copper solid and heat
pipes arranged as shown in FIG. 11. In this example, the copper
solid 21 is formed integrally with the base portion 8. The inside
of the base portion 8 has three heat pipes 5 arranged as described
above. A heat source 30 contacts a portion of the copper solid 21
and a portion of the base portion 8. A fin portion 3 is mounted on
the top surface of the copper solid 21 and the top surface of a
second plate member. As with the above-described examples, spaces
(e.g., air passages) are formed around the peripheral portion of
the heat pipe 5.
[0086] The heat pipe 5 is equipped with a sealed metal tube
containing a small amount of working fluid. Heat is transferred by
the phase change (between vaporization of the working fluid and
condensation of the vapor) and movement of the working fluid. Part
of the heat from the heat source 30 is transferred through the
container constituting the heat pipe 5, but most of the heat is
transferred by the phase change and movement of the working
fluid.
[0087] More specifically, heat from the heat source 30 (e.g.,
electronic equipment) is absorbed at one end of the heat pipe 5 by
vaporization of the working fluid and is dissipated at the other
end by condensation of the vapor. And the working fluid returns to
the one end of the heat pipe. Thus, heat transfer is performed by
the phase change and movement of the working fluid.
[0088] The working fluid within the heat pipe 5 normally uses
water, an aqueous solution, alcohol, an organic solvent, etc. There
are cases where mercury is used in a special application. As
previously mentioned, the heat pipe makes use of the phase change
of the working fluid, so the heat pipe is made so that gases, etc.,
are not mixed with the working fluid. Such a mixture is normally
the surrounding air that enters during the making of the heat pipe,
carbonic acid gas contained in the working fluid, etc. In addition
to a typical round heat pipe, a flat type is also widely used. Heat
transferred by heat pipes may be forcibly cooled by using a fan,
etc.
[0089] The material of the container of the heat pipe can use a
high conductive metal such as copper, aluminum, etc. To form a
flattened shape, aluminum is preferred. The wick can use a member
of the same material as the container of a flattened heat pipe. The
working fluid uses water, alternate chlorofluorocarbons (CFCs), or
fluorinated fluid, depending on compatibility with the material of
the container of a heat pipe.
[0090] The functions of the heat sink of the present invention will
hereinafter be described in detail.
[0091] A description will be given in the case where a small heat
source is arranged at one end of the heat sink. Heat is first
transferred from a heat source to the first plate member through a
thermal interface (grease or heat-transfer sheet). Heat is diffused
in the first plate member to some degree by the heat conduction of
the first plate member itself and is transferred to the heat pipes
thermally contacted with the first plate member. In the case of a
plurality of heat pipes, heat is spread by the spreading effect of
the first plate member, and flows in heat pipes without
concentrating on one heat pipe. The heat pipes are placed between
the first plate member and the second plate member that is provided
with fins. Since the heat pipes are installed across approximately
the entire length of the first plate member, thermal diffusion is
performed so that the second plate member is approximately
uniformly heated during the heat transfer from the first plate
member to the second plate member.
[0092] This thermal diffusion is performed by the heat-transfer
characteristic and uniform heating characteristic of heat pipes. If
the above-described plates, heat pipes, fins, etc., are joined at a
time with solder, the soldering step can be simplified. In ordinary
heat sinks, heat is dissipated to environment by convective air,
and the surrounding air passes through only the spaces between
fines. On the other hand, in the heat sink of the present
invention, the surrounding air passes through air passages formed
around the heat pipes as well as the spaces between fins, so heat
exchange is efficiently performed. In addition, since the air
passage is enlarged, air resistance is small. Therefore, high
performance can be realized with the same fan, and low noise and
low power consumption can be realized with the same amount of the
surrounding air.
[0093] FIG. 13 shows a third arrangement of heat pipes. FIG. 14 is
a sectional view taken along line A-A' of FIG. 13. As shown in FIG.
13, at a portion of a first plate member 4 corresponding to a
position where a heat source 30 is arranged, three heat pipes 5 are
arranged close to each other at a predetermined spacing. That is,
as shown in FIG. 14, predetermined air passages 6 are assured
between the heat pipes 5. The spacing between the heat pipes 5 is
parallel near the heat source 30 and is gradually enlarged toward
the other end of the first plate member 4.
[0094] In the example shown in FIGS. 13 and 14, spaces (e.g., air
passages) are formed around the heat pipes 5 arranged within the
base portion 8. Air passages are also assured around the heat pipes
5 near the heat source 30, and the surrounding air flows in the air
passages. Thus, heat from the heat source 30 can be efficiently
dissipated. That is, in the case where the surrounding air flows
from the wider spacing between the heat pipes 5, the flow of the
surrounding air is concentrated near the heat source 30 and
therefore greater flow speed is obtained.
[0095] FIG. 15 shows a fourth arrangement of heat pipes. FIG. 16 is
a sectional view taken along line A-A' of FIG. 15. FIG. 17 is a
sectional view taken along line B-B' of FIG. 15. As shown in these
figures, a heat source 30 is arranged at the central portion of a
first plate member 4. At a portion of the first plate member 4
corresponding to a position where the heat source 30 is arranged,
three heat pipes 5 are arranged close to each other at a
predetermined spacing. That is, as shown in FIG. 16, predetermined
air passages 6 are ensured between the heat pipes 5. The spacing
between the heat pipes 5 is parallel near the heat source 30 and is
gradually enlarged toward both ends of the first plate member
4.
[0096] As shown in FIG. 17, the air passage between the heat pipes
5 is broader at both ends of the first plate member 4. Since spaces
(e.g., air passages) are formed around the heat pipes 5 arranged
within the base portion 8, air passages is ensured around the heat
pipe 5 near the heat source 30 and the surrounding air flows. Thus,
heat from the heat source 30 can be efficiently dissipated.
Particularly, the spacing between the heat pipes 5 is gradually
enlarged from the central portion of the first plate member 4
toward both ends, so even if the surrounding air flows in any
direction, it flows effectively near the heat source 30 and
therefore the heat dissipating efficiency can be enhanced.
Furthermore, the heat pipes 5 can be approximately radially
arranged from the center portion, so the heat dissipating
efficiencies of the base portion 8 and fin portion 3 are
enhanced.
Embodiment 1
[0097] The heat sink 1 with heat pipes 5 of the present invention
shown in FIG. 1 was made. In this embodiment, a copper plate of 1.2
mm in thickness was used in the first plate member 4 and a copper
plate of 0.8 mm in thickness was used in the second plate member 2.
Three flattened heat pipes which are transformed from 6 mm in
diameter to 3 mm in thickness were arranged between the first and
second plate members. The height was 20 mm in total. The three heat
pipes were arranged at equal spaces within the base portion 8. The
fin thickness was 0.3 mm.
[0098] A heat source is arranged at the center of the short edge of
the first plate member and at a position 20 mm away from one end of
the long edge. Although one of the three heat pipes was positioned
just above the heat source, heat was also distributed to the
remaining two heat pipes. Therefore, an increase in the amount of
input heat and the heat density, which can cause the dry-out of the
heat pipes, could be reduced. In addition, since the heat pipe is
extended from one end of the long edge to the other end, the entire
base portion 8 can be uniformly heated. Convective air also passes
through the air passage formed around the heat pipe arranged within
the base portion 8. Therefore, more heat could be efficiently
dissipated at a position closer to the heat source. Furthermore,
because the area of the air passage is gradually increased, the
resistance to the air passage is reduced.
Embodiment 2
[0099] The heat sink 10 with heat pipes 15 of the present invention
shown in FIG. 5 was made. The construction is nearly the same as
the embodiment 1, but the metal block 17 is provided between the
first plate member 14 and the second plate member 12. The metal
block (or center block) 17 of 10 mm in width is provided at the
center portion of the short edge of the first plate member 14 and
extends from one end of the long edge to the other end. On both
sides of the center block, there are provided two heat pipes. The
heat pipe is approximately 15 mm in width.
[0100] The position of a heat source is the same as the embodiment
1. In this case, the center block is positioned just above the heat
source, and the thermal diffusion effect is further obtained in
addition to the thermal diffusion effect of the first plate member
of 1.2 mm in thickness. As a result, heat flux is reduced when heat
is transferred to the heat pipe, so even when calorific value of
the heat source is greater than that of the embodiment 1, there is
no possibility that the so-called dryout phenomenon will occur. In
addition, the broad heat pipe is great in the amount of heat
transfer per pipe, so the heat-transfer ability is great. Although
the number of heat pipes is two, this embodiment can cope with a
heat source of larger capacity than that in the embodiment 1.
[0101] While the present invention has been described with
reference to the preferred embodiments thereof, the invention is
not to be limited to the details given herein, but may be modified
within the scope of the invention hereinafter claimed. For example,
the material of each member is not limited to copper, but may be
aluminum or plated aluminum. The joining of the fins and the second
plate member is not limited to soldering, but they may be
mechanically joined. The heat pipe is not limited to a round pipe
and a flattened pipe, but may be a heat-transfer element utilizing
latent heat of vaporization. The length, diameter, and flatness of
the heat pipe and the number of pipes can be freely selected.
[0102] The first and second plate members and fin thickness can be
freely selected.
[0103] As set forth above, the present invention is capable of
providing a heat sink that requires a reduced a machine work. The
invention is also capable of providing a heat sink that is light in
weight, low in cost, and high in performance.
* * * * *