U.S. patent application number 11/918876 was filed with the patent office on 2009-03-12 for liquid cooling jacket.
This patent application is currently assigned to Nippon Light Metal Company, Ltd.. Invention is credited to Harumichi Hino, Hisashi Hori, Yoshimasa Kasezawa, Tsunehiko Tanaka, Takeshi Yoshida.
Application Number | 20090065178 11/918876 |
Document ID | / |
Family ID | 37214696 |
Filed Date | 2009-03-12 |
United States Patent
Application |
20090065178 |
Kind Code |
A1 |
Kasezawa; Yoshimasa ; et
al. |
March 12, 2009 |
Liquid cooling jacket
Abstract
A liquid cooling jacket (J1) transmits heat generated by a CPU
(101) which is installed at a predetermined position to coolant
supplied from an external heat transmission fluid supply means and
flowing inside of the liquid cooling jacket. The liquid cooling
jacket includes a first flow passage (A1) on a side of the heat
transmission fluid supply means, a second flow passage group (B1)
including a plurality of second flow passages (B1a) branched from
the first flow passage (A1), and a third flow passage (C1)
installed at downstream side of the plurality of the second flow
passages (B1a), and collecting the plurality of the second flow
passages (B1a), wherein the CPU (101) mainly dissipates the heat to
the second flow passage group (B1).
Inventors: |
Kasezawa; Yoshimasa;
(Shizuoka, JP) ; Hori; Hisashi; (Shizuoka, JP)
; Hino; Harumichi; (Shizuoka, JP) ; Tanaka;
Tsunehiko; (Shizuoka, JP) ; Yoshida; Takeshi;
(Shizuoka, JP) |
Correspondence
Address: |
SQUIRE, SANDERS & DEMPSEY L.L.P.
8000 TOWERS CRESCENT DRIVE, 14TH FLOOR
VIENNA
VA
22182-6212
US
|
Assignee: |
Nippon Light Metal Company,
Ltd.
|
Family ID: |
37214696 |
Appl. No.: |
11/918876 |
Filed: |
April 13, 2006 |
PCT Filed: |
April 13, 2006 |
PCT NO: |
PCT/JP2006/307846 |
371 Date: |
October 19, 2007 |
Current U.S.
Class: |
165/104.19 ;
165/104.28; 165/104.33 |
Current CPC
Class: |
H01L 23/473 20130101;
H01L 2924/0002 20130101; B21J 5/068 20200801; H01L 2924/0002
20130101; H01L 2924/00 20130101 |
Class at
Publication: |
165/104.19 ;
165/104.28; 165/104.33 |
International
Class: |
F28D 15/00 20060101
F28D015/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 21, 2005 |
JP |
2005-123403 |
Claims
1. A liquid cooling jacket for transmitting heat generated by a
heating element which is installed to a predetermined position to a
heat transmission fluid supplied from an external heat transmission
fluid supply means and flowing inside of the liquid cooling jacket,
the liquid cooling jacket comprising: a first flow passage on a
side of the heat transmission fluid supply means; a second flow
passage group consisting of a plurality of second flow passages
branched from the first flow passage, and a third flow passage
installed at downstream side of the plurality of the second flow
passages, and collecting the plurality of the second flow passages,
wherein the heating element mainly dissipates the heat to the
second flow passage group.
2. A liquid cooling jacket for transmitting heat generated by a
heating element which is installed to a predetermined position to a
heat transmission fluid supplied from an external heat transmission
fluid supply means and flowing inside of the liquid cooling jacket,
the liquid cooling jacket comprising: a first flow passage, a
plurality of a second flow passage groups each of which consists of
a plurality of second flow passages, and a third flow passage
toward downstream in order, wherein the heating element mainly
dissipates the heat to the second flow passage groups, and the
adjacent second flow passage groups are connected in series via a
communication flow passage.
3. The liquid cooling jacket according to claim 2, wherein the
adjacent second flow passage groups are disposed side by side, and
a lower end of one of the adjacent second flow passage groups and
an upper end of the other one of the adjacent second flow passage
groups are on the same side.
4. The liquid cooling jacket according to claim 1, comprising a
tube bundle formed by bundling a plurality of metallic tubes,
wherein an inner hole of each of the plurality of metallic tubes is
the second flow passage.
5. The liquid cooling jacket according to claim 1, further
comprising a metallic tube having a plurality of inner holes,
wherein each of the inner holes is the second flow passage.
6. The liquid cooling jacket according to claim 1, further
comprising a plurality of metallic fins arranged at a predetermined
interval, wherein a space between the adjacent fins is the second
flow passage.
7. The liquid cooling jacket according to claim 6, wherein a width
W of the second flow passage is in the range of 0.2 to 1.1 mm.
8. The liquid cooling jacket according to claim 6, wherein the
width W of the second flow passage and a thickness T of the fins
disposed between the adjacent second flow passages satisfy Formula
1. -0.375.times.W+0.875.ltoreq.T/W.ltoreq.-1.875.times.W+3.275
Formula 1
9. The liquid cooling jacket according to claim 6, wherein a depth
D of the second flow passage and the width W of the second flow
passage satisfy Formula 2.
5.times.W+1.ltoreq.D.ltoreq.-16.25.times.W+2.75 Formula 2
10. The liquid cooling jacket according to claim 6, further
comprising: a fin member comprising the plurality of metallic fins
and a base from which the plurality of metallic fins are extended;
a jacket body for housing the fin member, wherein the base is
heat-exchangeably fixed to the jacket body.
11. The liquid cooling jacket according to claim 6, further
comprising: a first fin member comprising a first base and a
plurality of first fins extended from the first base; a second fin
member comprising a second base and a plurality of second fins
extended from the second base, wherein the first fin member and the
second fin member are combined such that the plurality of the first
fins and the plurality of the second fins are interlocked together,
the plurality of metallic fins are composed of the first fins and
the second fins, and the second flow passage is formed between the
first fin and the second fin adjacent to each other.
12. The liquid cooling jacket according to claim 11, wherein the
heating element is installed on a side of the first base, a
protruding length of the first fin is set to be equal to or shorter
than a protruding length of the second fin, and the plurality of
the second fins is thermally connected to the first base.
13. The liquid cooling jacket according to claim 6, further
comprising: a jacket body comprising a fin housing for housing the
plurality of the metallic fins; a sealing member for sealing the
fin housing; wherein a contact area where a peripheral wall of the
jacket body surrounding the fin housing and the sealing member are
in contact with each other is friction stir welded, and a start end
of the area which is friction stir welded overlaps with a finish
end of the area which is friction stir welded.
14. The liquid cooling jacket according to claim 13, wherein the
plurality of metallic fins is extended from the sealing member and
integrally formed with the sealing member.
15. The liquid cooling jacket according to claim 13, wherein the
peripheral wall is friction stir welded with a jig holding the
peripheral wall so that the peripheral wall does not protrude
outward.
16. The liquid cooling jacket according to claim 13, wherein a
length of a pin of a tool to be used in the friction stir welding
is less than or equal to 60% of a thickness of the sealing
member.
17. The liquid cooling jacket according to claim 13, wherein a
position where the tool is pulled apart does not overlap with the
contact area in the friction stir welding.
18. The liquid cooling jacket according to claim 1, further
comprising a metallic honeycomb member comprising a plurality of
minute holes, wherein each of the plurality of minute holes is the
second flow passage.
19. The liquid cooling jacket according to claim 1, further
comprising: a ripple cross-section metallic heat dissipating sheet,
and a metallic jacket body to which the heat dissipating sheet is
heat-exchangeably fixed, wherein the second flow passage is formed
between the heat dissipating sheet and the jacket body.
20. The liquid cooling jacket according to claim 6, wherein the
metal is aluminum or aluminum alloy.
21. The liquid cooling jacket according to claim 1, wherein a heat
transmission fluid inlet communicating with the first flow passage
and a heat transmission fluid outlet communicating with the third
passage are arranged symmetric with respect to the heating
element.
22. The liquid cooling jacket according to claim 21, wherein the
inlet and the outlet are arranged relatively away from each
other.
23. The liquid cooling jacket according to claim 21, wherein the
inlet and the outlet are arranged such that the inlet and the
outlet come closer to the heating element.
24. The liquid cooling jacket according to claim 1, wherein the
heating element is a CPU.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a liquid cooling jacket for
cooling a heating element such as a CPU.
[0002] In recent years, cooling a CPU (Central Processing Unit) (a
heating element) becomes more and more important because the
heating value of a CPU has been increasing with the improvement of
the performance of electronic devices such as a personal computer.
Conventionally, a heat sink air-cooling fan has been used to cool a
CPU. However, the heat sink air cooling fan has problems of fan
noise and cooling limit. Thus, a liquid cooling jacket (also
referred to as a water cooling jacket or a liquid cooling module)
has been receiving attention as a next generation cooling
method.
[0003] As for such a technique, Japanese Laid-open Patent
Application No. 1988-293865 discloses a liquid cooling jacket
incorporating a serpentine metallic tube wherein an inlet and an
outlet are provided at ends of the metallic tube (see page 2, line
2 in an upper right column to page 2, line 15 in a lower left
column, FIG. 1 and FIG. 2).
DISCLOSURE OF THE INVENTION
Problems to be Solved
[0004] However, a coolant incurs a large pressure loss when a
liquid cooling jacket comprises only one flow passage through which
the coolant flows as shown in the patent document. This causes
problems that not only a CPU cannot be cooled efficiently, but also
the output power of a pump has to be increased to supply the
coolant.
[0005] In view of the above, the present invention seeks to provide
a liquid cooing jacket which is able to cool a heating element such
as a CPU efficiently.
Means to Solve the Problems
[0006] In order to solve the above problems, there is provided a
liquid cooling jacket for transmitting heat generated by a heating
element which is installed to a predetermined position, to a heat
transmission fluid supplied from an external heat transmission
fluid supply means and flowing inside of the liquid cooling jacket,
the liquid cooling jacket including a first flow passage on a side
of the heat transmission fluid supply means, a second flow passage
group consisting of a plurality of second flow passages branched
from the first flow passage, a third flow passage installed at
downstream side of the plurality of the second flow passages, and
collecting the plurality of the second flow passages, wherein the
heating element mainly dissipates the heat to the second flow
passage group.
[0007] In accordance with the liquid cooling jacket, the heat
transmission fluid is supplied to the first flow passage from the
external heat transmission supply means. Then, the heat
transmission fluid flows through the second flow passage group and
the third flow passage in sequence. The heat generated by the
heating element is mainly dissipated to the second flow passage
group and then transmitted to the heat transmission fluid. As a
result, the heating element is efficiently cooled.
[0008] In the liquid cooling jacket, the second flow passage group
consists of the second flow passages branched from the first flow
passage, and the plurality of the second flow passages is collected
by the third flow passage. In accordance with this configuration, a
length of each of the second flow passages is remarkably shorter
than that of the second flow passage of the liquid cooling jacket
comprising only one serpentine second flow passage. Accordingly,
the pressure loss of the heat transmission fluid flowing through
the plurality of the second passages is remarkably lower than that
of the heat transmission fluid flowing through the long second flow
passage. It is also to be noted that the second flow passages
adjacent to each other do not have to be completely isolated in the
present invention, as shown in second flow passages 5a, 5a of a
liquid cooling jacket J6 according to a sixth embodiment of the
present invention, which is described later (refer to FIG. 26).
[0009] In accordance with the liquid cooling jacket, the heat
transmission fluid can be supplied and made to flow inside the
liquid cooling jacket, and the heating element such as a CPU can be
cooled efficiently by using the external heat transmission fluid
supply means of which an output power is small (e.g. a pump).
[0010] There is also provided a liquid cooling jacket for
transmitting heat generated by a heating element which is installed
to a predetermined position, to a heat transmission fluid supplied
from an external heat transmission fluid supply means and flowing
inside of the liquid cooling jacket, the liquid cooling jacket
comprising: a first flow passage, a plurality of a second flow
passage groups each of which consists of a plurality of second flow
passages, and a third flow passage toward downstream in order,
wherein the heating element mainly dissipates the heat to the
second flow passage groups, and the adjacent second flow passage
groups are connected in series via a communication flow passage. In
short, this is a liquid cooling jacket wherein a plurality of the
second flow passage groups is provided and the plurality of the
second flow passage groups is connected in series.
[0011] In accordance with this liquid cooling jacket, because the
liquid cooling jacket is provided with the plurality of the second
flow passage groups connected in series via the communication flow
passage, the heat can be exchanged between the plurality of the
second flow passages and the heating element.
[0012] In the aforementioned liquid cooling jacket, the adjacent
second flow passage groups may be disposed side by side, and a
lower end of one of the adjacent second flow passage groups and an
upper end of the other one of the adjacent second flow passage
groups may be on the same side. That is, this is a liquid cooling
jacket wherein the adjacent second flow passage groups are disposed
side by side, and a lower end of one of the adjacent second flow
passage groups and an upper end of the other one of the adjacent
second flow passage groups are on the same side.
[0013] In accordance with this liquid cooling jacket, the heat
transmission fluid meanders through one of the second flow passage
groups adjacent in a flowing direction of the heat transmission
fluid, the communication flow passage and the other one of the
adjacent second flow passage groups. Therefore, when the size of
the liquid cooling jacket in a plain view is constant, if the
number of the second flow passage groups is increased without
changing the number of the second flow passages constituting each
of the second passage groups, a cross-sectional area of each of the
second flow passages constituting each of the second flow passage
groups becomes smaller. Therefore, when a flow rate of the heat
transmission fluid flowing through the liquid cooling jacket is
constant, if the number of the second flow passage groups is
increased, a flow speed of the heat transmission fluid in each of
the second flow passages is increased. Thus, thermal conductivity
between the liquid cooling jacket and the heat transmission fluid
is increased, and thermal resistance of the liquid cooling jacket
decreases accordingly.
[0014] On the contrary, when the adjacent second flow passage
groups are not disposed side by side, but disposed in line in the
flowing direction, for example, even if the number of the second
flow passage group is increased, a length of each of the second
flow passages constituting each of the second flow passage groups
becomes shorter, but a cross-sectional area of each of the second
flow passages does not become smaller, and thus a flow speed of the
heat transmission fluid is not increased either. Therefore, the
thermal resistance of the liquid cooling jacket does not
decrease.
[0015] If the number of the second flow passage groups is even
number, the inlet of the liquid cooling jacket for the heat
transmission fluid and the outlet thereof can be arranged on the
same side. This makes it possible to readily install piping to the
liquid cooling jacket.
[0016] The aforementioned liquid cooling jackets may further
include a tube bundle formed by bundling a plurality of metallic
tubes, wherein an inner hole of each of the plurality of metallic
tubes is the second flow passage.
[0017] In accordance with the liquid cooling jackets, which include
the tube bundle formed by bundling the plurality of metallic tubes,
the inner holes of each of the plurality of metallic tubes become
the second flow passage. This makes it possible to readily
construct the liquid cooling jacket. It is also possible to readily
change the number of the second flow passages and a cross sectional
area of the second flow passage by changing the number of the
metallic tubes to be bundled and the size thereof as
appropriate.
[0018] The aforementioned liquid cooling jackets may further
include a metallic tube having a plurality of inner holes, wherein
each of the inner holes is the second flow passage.
[0019] In accordance with the liquid cooling jackets, it is
possible to readily construct the liquid cooling jackets, using the
metallic tube having the plurality of inner holes.
[0020] The aforementioned liquid cooling jackets may further
include a plurality of metallic fins arranged at a predetermined
interval, wherein a space between the adjacent fins is the second
flow passage.
[0021] In accordance with the liquid cooling jackets, because the
space between the adjacent fins is the second flow passage, it is
possible to transmit the heat generated by the heating element to
the heat transmission fluid flowing through the second flow passage
via the plurality of the fins.
[0022] In the aforementioned liquid cooling jackets, a width W of
the second flow passage may be 0.2.about.1.0 mm.
[0023] In accordance with the liquid cooling jackets, it is
possible to make the thermal resistance and the pressure loss of
the heat transmission fluid flowing inside the liquid cooling
jackets to be within a preferable range.
[0024] In the aforementioned liquid cooling jackets, the width W of
the second flow passage and a thickness T of the fins disposed
between the adjacent second flow passages may satisfy Formula
1.
-0.375.times.W+0.875.ltoreq.T/W.ltoreq.-1.875.times.W+3.275 Formula
1
[0025] In accordance with the liquid cooling jackets, the thermal
resistance decreases and the heat can be efficiently exchanged
between the heating element and the heat transmission fluid.
[0026] In the aforementioned liquid cooling jackets, a depth D of
the second flow passage and the width W of the second flow passage
may satisfy Formula 2.
5.times.W+1.ltoreq.D.ltoreq.-16.25.times.W+2.75 Formula 2
[0027] In accordance with the liquid cooling jackets, the thermal
resistance decreases and the heat can be efficiently exchanged
between the heating element and the heat transmission fluid.
[0028] The aforementioned liquid cooling jackets may further
comprise a fin member comprising the plurality of metallic fins and
a base from which the plurality of metallic fins is extended, a
jacket body for housing the fin member, wherein the base is
heat-exchangeably fixed to the jacket body.
[0029] The aforementioned liquid cooling jackets can be
constructed, for example, by the following process. At first, a fin
member comprising the plurality of fins is manufactured by cutting
a metallic extrusion having a plurality of protruded lines, which
is a plurality of fins extended from a base plate, and a base which
is the base plate. Then, the fin member is fixed to a box-shaped
jacket body.
[0030] The aforementioned liquid cooling jackets may further
comprise a first fin member comprising a first base and a plurality
of first fins extended from the first base, a second fin member
comprising a second base and a plurality of second fins extended
from the second base, wherein the first fin member and the second
fin member are combined such that the plurality of the first fins
and the plurality of the second fins are interlocked together, the
plurality of metallic fins are composed of the first fins and the
second fins, and the second flow passage is formed between the
first fin and the second fin adjacent to each other.
[0031] In accordance with the liquid cooling jackets, because the
plurality of the first fins and the plurality of the second fins
are interlocked together, even if an interval of each of the first
fins and that of each of the second fins are wide, an interval of
the adjacent fins, that is an interval of the first fin and the
second fin can be made narrow.
[0032] In the aforementioned liquid cooling jackets, the heating
element may be installed on the side of the first base, a
protruding length of the first fin may be set to be equal to or
shorter than a protruding length of the second fin, and the
plurality of the second fins may be thermally connected to the
first base.
[0033] In accordance with the liquid cooling jackets, because the
protruding length of the first fin is set to be equal to or shorter
than the protruding length of the second fin, when the first fin
member and the second fin member are combined, the plurality of the
second fins are ensured to be in contact with the first base. Then,
the plurality of the second fins is heat-exchangeably connected to
the first base to construct the liquid cooling jackets.
[0034] The heat generated by the heating element installed on the
side of the first base is transmitted to both of the plurality of
the first fins and the plurality of the second fins via the first
base. Thus, the heat can be transmitted to the heat transmission
fluid flowing through the second flow passage between the first fin
and the second fin.
[0035] The aforementioned liquid cooling jackets may further
comprise a jacket body comprising a fin housing for housing the
plurality of the metallic fins, a sealing member for sealing the
fin housing, wherein a contact area where a peripheral wall of the
jacket body surrounding the fin housing and the sealing member are
in contact with each other may be friction stir welded, and a start
end of the area which is friction stir welded may overlap with a
finish end of the area which is friction stir welded.
[0036] In accordance with the liquid cooling jackets, because the
start end of the area which is friction stir welded overlaps with
the finish end of the area which is friction stir welded, it is
possible to securely connect the peripheral wall of the jacket body
with the sealing member. This makes it difficult for the heat
transmission fluid to leak.
[0037] Further, because the sealing member and the jacket body are
connected by the friction stir welding without using a brazing
filler metal and the like, the heat transmission fluid is not
contaminated by the brazing filler metal and the like, and
furthermore, devices constituting the liquid cooling system, such
as a micro pump and a radiator are not corroded by the brazing
filler metal and the like.
[0038] In the aforementioned liquid cooling jackets, the plurality
of metallic fins may be extended from the sealing member and
integrally formed with the sealing member.
[0039] In accordance with the liquid cooling jackets, because the
plurality of metallic fins and the sealing member are integrally
formed, the fin housing can be sealed by the sealing member, and
the plurality of metallic fins can be disposed at a predetermined
position in the fin housing. Therefore, manufacturing process of
the liquid cooling jackets can be simplified, which makes it easy
to manufacture the liquid cooling jackets, and the manufacturing
cost can be also reduced. The sealing member integrally formed with
the plurality of metallic fins is, for example, constructed by
skiving an aluminum alloy plate as shown in a fifth embodiment of
the present invention, which is described later.
[0040] If the fins and the sealing member are integrally formed by
the skive process, the fins and the sealing member do not have to
be connected by the brazing filler metal and the like. Therefore,
the heat transmission fluid can be prevented from being
contaminated by the brazing filler metal and the like.
[0041] Furthermore, because the fins and the sealing member are
single-membered, the heat conductivity between the fins and the
sealing member is high. Therefore, the heat of the heating element
is efficiently transmitted to the plurality of fins via the sealing
member when the heating element such as a CPU is installed at the
sealing member. Thus, heat radiation performance of the heating
element in the liquid cooling jackets becomes high.
[0042] In the aforementioned liquid cooling jackets, the peripheral
wall may be friction stir welded with a jig holding the peripheral
wall so that the peripheral wall does not protrude outward.
[0043] In accordance with the liquid cooling jackets, because the
peripheral wall is friction stir welded with the jig holding the
peripheral wall, the peripheral wall does not protrude outward
easily. Even if the peripheral wall is thin, and an interval
between an outer surface of a shoulder of a tool used for the
friction stir welding and the outer surface of the peripheral wall
is less than or equal to, for example, 2.0 mm, it is possible to
carry out the friction stir welding without making the peripheral
wall protrude outward when the jig holds the peripheral wall as
described above.
[0044] In the aforementioned liquid cooling jackets, a length of a
pin of a tool to be used in the friction stir welding may be less
than or equal to 60% of a thickness of the sealing member.
[0045] In accordance with the liquid cooling jackets, by making the
length of the pin of the tool to be less than or equal to 60% of
the thickness of the sealing member, the sealing member becomes not
to protrude toward the fin housing easily in the friction stir
welding. Thus, a volume of the fin housing can be prevented from
being reduced.
[0046] In the aforementioned liquid cooling jackets, a position
where the tool is pulled apart may not overlap with the contact
area in the friction stir welding.
[0047] In accordance with the liquid cooling jackets, because the
position where the tool is pulled apart does not overlap with the
contact area, a trace of the pin which is pulled apart does not
remain in the contact area. Thus, the jacket body and the sealing
member can be securely connected.
[0048] The aforementioned liquid cooling jackets may further
comprise a metallic honeycomb member comprising a plurality of
minute holes, wherein each of the plurality of minute holes is the
second flow passage.
[0049] In accordance with the liquid cooling jackets, because each
of the plurality of minute holes is the second flow passage, the
heat of the heating element can be transmitted to the heat
transmission fluid flowing through the second passage via the
honeycomb member.
[0050] The aforementioned liquid cooling jackets may further
comprise a ripple cross-section metallic heat dissipating sheet and
a metallic jacket body to which the heat dissipating sheet is
heat-exchangeably fixed, wherein the second flow passage is formed
between the heat dissipating sheet and the jacket body.
[0051] The liquid cooling jackets can be easily constructed by
heat-exchangeably fixing the ripple cross-section metallic heat
dissipating sheet to the jacket body.
[0052] In the aforementioned liquid cooling jackets, the metal may
be aluminum or aluminum alloy.
[0053] In accordance with the liquid cooling jackets, by using
aluminum and aluminum alloy as the metal, a weight of the liquid
cooling jackets can be reduced.
[0054] In the aforementioned liquid cooling jackets, a heat
transmission fluid inlet communicating with the first flow passage
and a heat transmission fluid outlet communicating with the third
passage may be arranged symmetric with respect to the heating
element.
[0055] In accordance with the liquid cooling jackets, the heat
transmission fluid supplied to the first flow passage from the
inlet is easy to flow through second flow passages which are close
to the heating element. Thus, the heat can be efficiently exchanged
between the heat transmission fluid and the heating element.
[0056] In the aforementioned liquid cooling jackets, the inlet and
outlet may be arranged relatively away from each other.
[0057] In accordance with the liquid cooling jackets, the heat
transmission fluid supplied from the inlet to the first flow
passage is easy to flow through the whole of the plurality of the
second flow passages. Thus, the heat can be efficiently transmitted
between the heat transmission fluid flowing through the whole of
the plurality of the second passage and the heating element.
[0058] In the aforementioned liquid cooling jackets, the inlet and
the outlet may be arranged such that the inlet and the outlet come
closer to the heating element.
[0059] In accordance with the liquid cooling jackets, the heat
transmission fluid supplied to the first flow passage from the
inlet is easy to flow through the second flow passages which are
close to the heating element in high flow speed. Thus, the heat can
be efficiently transmitted between the heat transmission fluid
flowing through the second flow passages close to the heating
element in high flow speed, and the heating element. For example,
even if the heating element such as a CPU is not installed at the
liquid cooling jackets via a heat dissipating sheet 102 (see FIG.
3), which is called a heat spreader, and thus the heat of the
heating element is difficult to be transmitted to the whole of the
liquid cooling jackets, the liquid cooling jackets can be radiated
efficiently by making the heat transmission fluid to flow through
the second flow passages close to the heating element in high flow
speed.
[0060] In the aforementioned liquid cooling jackets, the heating
element may be a CPU.
[0061] In accordance with the liquid cooling jackets, the heat is
efficiently exchanged between the CPU and the heat transmission
fluid, and thus the CPU can be cooled.
[0062] According to the present invention, there is provided a
liquid cooling jacket capable of efficiently cooling a heating
element such as a CPU. Other features, advantages and aspects of
the present invention will be apparent from the following
illustrative and non-restrictive description of preferred
embodiments of the present invention taken in conjunction with the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0063] FIG. 1 is a block diagram of a liquid cooling system
according to a first embodiment.
[0064] FIG. 2 is a perspective view of a liquid cooling jacket
according to the first embodiment.
[0065] FIG. 3 is a bottom perspective view of the liquid cooling
jacket according to the first embodiment.
[0066] FIG. 4 is a perspective view of the liquid cooling jacket
according to the first embodiment, in which a lid unit is
omitted.
[0067] FIG. 5 is a plain view of the liquid cooling jacket
according to the first embodiment.
[0068] FIG. 6 is a cross-sectional view of the liquid cooling
jacket according to the first embodiment along a line X-X shown in
FIG. 2.
[0069] FIG. 7 is an exploded perspective view of the liquid cooling
jacket according to the first embodiment.
[0070] FIG. 8 is a graph schematically showing an effect of the
liquid cooling jacket according to the first embodiment.
[0071] FIG. 9 is a perspective view of a liquid cooling jacket
according to a second embodiment, in which a lid unit is
omitted.
[0072] FIG. 10 is a cross-sectional view of the liquid cooling
jacket according to the second embodiment along a line Y-Y shown in
FIG. 9.
[0073] FIG. 11 is a perspective view of a liquid cooling jacket
according to a third embodiment.
[0074] FIG. 12 is a plain view of the liquid cooling jacket
according to the third embodiment.
[0075] FIG. 13 is a perspective view of a liquid cooling jacket
according to a fourth embodiment, in which a lid unit is
omitted.
[0076] FIG. 14 is a cross-sectional view of the liquid cooling
jacket according to the fourth embodiment along a line Z-Z shown in
FIG. 13.
[0077] FIG. 15 is an enlarged view of the cross-sectional view
along the line Z-Z shown in FIG. 14.
[0078] FIG. 16 is a perspective view of a first manufacture method
of a fin member of the liquid cooling jacket according to the
fourth embodiment; FIG. 16A shows an extrusion before it is cut;
and FIG. 16B shows the fin member after the extrusion is cut.
[0079] FIG. 17 is a perspective view of a second manufacture method
of a fin member of the liquid cooling jacket according to the
fourth embodiment; FIG. 17A shows an extrusion before it is cut;
and FIG. 17B shows the fin member after the extrusion is cut.
[0080] FIG. 18 is a perspective view showing a friction stir
welding according to the fourth embodiment.
[0081] FIG. 19 is a cross-sectional view showing the friction stir
welding according to the fourth embodiment.
[0082] FIG. 20 is a plain view showing movement of a tool to be
used for the friction stir welding.
[0083] FIG. 21 is a cross-sectional view of a liquid cooling jacket
according to a fifth embodiment.
[0084] FIG. 22 is an enlarged view of the cross-sectional view
shown in FIG. 21.
[0085] FIG. 23 is a view showing a manufacture method of a fin
member of the liquid cooling jacket according to the fifth
embodiment; FIG. 23A shows the fin member during a skive process;
and FIG. 23B shows the fin member after the skive process has
completed.
[0086] FIG. 24 is a view showing the manufacture method of the fin
member of the liquid cooling jacket according to the fifth
embodiment, illustrating the fin member after parts of the skive
fins are removed.
[0087] FIG. 25 is a cross-sectional view showing a friction stir
welding according to the fifth embodiment.
[0088] FIG. 26 is a cross-sectional view of a liquid cooling jacket
according to a sixth embodiment; FIG. 26A shows the liquid cooling
jacket after assembled; and FIG. 26B shows the liquid cooling
jacket before assembled.
[0089] FIG. 27 is a cross-sectional view of a liquid cooling jacket
according to a seventh embodiment; FIG. 27A shows the liquid
cooling jacket after assembled; and FIG. 27B shows the liquid
cooling jacket before assembled.
[0090] FIG. 28 is a cross-sectional view of a liquid cooling jacket
according to an eighth embodiment; FIG. 28A shows the liquid
cooling jacket after assembled; and FIG. 28B shows the liquid
cooling jacket before assembled.
[0091] FIG. 29 is a plane view of a liquid cooling jacket according
to a ninth embodiment.
[0092] FIG. 30 is a plane view of a liquid cooling jacket according
to a tenth embodiment.
[0093] FIG. 31 is a graph showing a relationship between the number
of times the coolant is turned and thermal resistance.
[0094] FIG. 32 is a cross-sectional view of a flat tube bundle
according to a modification.
[0095] FIG. 33 is a cross-sectional view of a liquid cooling jacket
according to a modification;
[0096] FIG. 33A shows the liquid cooling jacket after assembled;
and FIG. 33B shows the liquid cooling jacket before assembled.
[0097] FIG. 34 is a cross-sectional view of a liquid cooling jacket
according to a modification.
[0098] FIG. 35 is a perspective view of a liquid cooling jacket
according to a modification.
[0099] FIG. 36 is a graph showing a relationship between a groove
width W1 and heat resistance, and a relationship between the groove
width W1 and a pressure loss.
[0100] FIG. 37 is a graph showing a relationship between a fin
thickness T1 divided by the groove width W1 and heat
resistance.
[0101] FIG. 38 is a graph showing a relationship between the groove
width W1 and the fin thickness T1 divided by the groove width
W1.
[0102] FIG. 39 is a graph showing a relationship between a groove
depth D1 and thermal resistance.
[0103] FIG. 40 is a graph showing a relationship between the groove
width W1 and the groove depth D1.
DESCRIPTION OF SYMBOLS
[0104] A1: First flow passage [0105] B1: Second flow passage group
[0106] B1a: Second flow passage [0107] C1: Third flow passage
[0108] J1: Liquid cooling jacket [0109] 10: Jacket body [0110] 10a:
Space [0111] 10c: Space [0112] 11: Bottom [0113] 12: Peripheral
wall [0114] 15: Step portion [0115] 20: Flat tube bundle [0116] 21:
Flat tube [0117] 21a: Inner hole [0118] 21b: Peripheral wall [0119]
21c: Partition wall [0120] 31: Lid body [0121] 31a: Inlet [0122]
31b: Outlet [0123] 101: CPU (Heating element) [0124] 200: Tool
[0125] 201: Pin [0126] 202: Shoulder [0127] 210: Jig [0128] K:
Friction stir welded portion [0129] L5: Pin length [0130] L6:
Length between the outer surface of the tool and the outer surface
of the peripheral wall [0131] P1: Contact area [0132] Q: Overlapped
area [0133] T1: Thickness of Fin [0134] T2: Thickness of Lid body
[0135] T11: Thickness of peripheral wall [0136] W1: Groove width
[0137] W11: Width of the step portion
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0138] Preferred embodiments of the present invention are described
in detail below with reference to the accompanying drawings
First Embodiment
[0139] A liquid cooling system and a liquid cooling jacket
according to a first embodiment are now described with reference to
FIG. 1 to FIG. 8. FIG. 1 is a block diagram of the liquid cooling
system according to the first embodiment. FIG. 2 is a perspective
view of a liquid cooling jacket according to the first embodiment.
FIG. 3 is a bottom perspective view of the liquid cooling jacket
according to the first embodiment. FIG. 4 is a perspective view of
the liquid cooling jacket according to the first embodiment, in
which a lid unit is omitted. FIG. 5 is a plain view of the liquid
cooling jacket according to the first embodiment, in which an inlet
pile and an outlet pipe are omitted. FIG. 6 is a cross-sectional
view of the liquid cooling jacket according to the first embodiment
along a line X-X shown in FIG. 2. FIG. 7 is an exploded perspective
view of the liquid cooling jacket according to the first
embodiment. FIG. 8 is a graph schematically showing an effect of
the liquid cooling jacket according to the first embodiment.
Construction of the Liquid Cooling System
[0140] As shown in FIG. 1, a liquid cooling system S1 according to
the first embodiment is a system equipped in a personal computer
120 (an electronic device) which is a tower configuration. The
liquid cooling system S1 cools a CPU 101 (heating element)
constituting the personal computer 120. The liquid cooling system
S1 mainly comprises a liquid cooling jacket to which the CPU 101 is
installed at a predetermined position, a radiator 121 (radiation
means) for radiating heat transmitted by coolant (heat transmission
fluid) outside, a micro pump 122 (heat transmission fluid supply
means) for circulating the coolant, a reserve tank 123 for
absorbing expansion and contraction of the coolant caused by
changes in temperature, a flexible tube 124 for connecting these
components, and the coolant for transmitting the heat. As the
coolant, ethylene glycol antifreeze liquid is used for example.
[0141] Once the micro pump 122 starts to operate, the coolant
circulates through the above devices.
Construction of the Liquid Cooling Jacket
[0142] The liquid cooling jacket J1 constituting the liquid cooling
system S1 is now described in detail. As shown in FIG. 2 and FIG.
3, the CPU 101 is installed at a center (predetermined position) of
a bottom (back side) of the liquid cooling jacket J1 via a heat
dissipating sheet 102 (heat spreader). When the CPU 101 is
installed as described above and the coolant flows inside of the
liquid cooling jacket J1, the liquid cooling jacket J1 receives
heat generated by the CPU 101 and dissipates the heat to the
coolant flowing inside of the liquid cooling jacket J1. Thus, the
liquid cooling jacket J1 transmits the heat received from the CPU
101 to the coolant. As a result, the CPU 101 is efficiently cooled.
The heat dissipating sheet is a sheet used for efficiently
transmitting the heat of the CPU 101 to a bottom 11 of a jacket
body 10, which will be described later. The heat dissipating sheet
is formed of metal having high thermal conductivity such as copper,
for example.
[0143] As shown in FIG. 4 to FIG. 7, the liquid cooling jacket J1
(mainly) comprises the jacket body 10, a flat tube bundle 20 (tube
bundle), and a lid unit 30. Unless specifically indicated, the
jacket body 10, the flat tube bundle 20 and the lid unit 30 are
formed of aluminum or aluminum alloy. Thus, the weight of the
liquid cooling jacket J1 is reduced, and it is easy to handle the
liquid cooling jacket J1.
The Jacket Body
[0144] The jacket body 10 is a shallow box of which upper side (one
side) is opened (see FIG. 7). The jacket body 10 comprises a bottom
11, a peripheral wall 12, and a housing for housing the flat tube
bundle 20 (see FIG. 7). The jacket body 10 is formed, for example,
by die casting, metal casting, forging and the like. The jacket
body 10 also comprises a fitting portion 14 of which shape
corresponds to a notch 31c of a lid body 31, which will be
described later, at a part of an opening end.
The Flat Tube Bundle
[0145] The flat tube bundle 20 is heat-exchangeably bonded and
fixed to the bottom 11 of the jacket body 10 by brazing filler
metal formed of Al--Si--Zn alloy and the like while a space 10a and
a space 10c are ensured to be left at both ends of the jacket body
10 (see FIG. 4 and FIG. 5). The space 10a has a function of a first
flow passage A1, and the space 10c has a function of a third flow
passage C1.
[0146] The flat tube bundle 20 is formed by bundling a
predetermined number of flat tubes 21 in the thickness direction
and connecting the flat tubes 21 (see FIG. 6 and FIG. 7). Each of
the flat tubes 21 comprises one or a plurality of inner holes 21a
(two inner holes in the first embodiment). Each of the inner holes
21a has a function of a second flow passage B1a. That is, each of
the second flow passages has a cross-sectional rectangular shape,
and is surrounded by side wall portions (second flow passage
components) formed by peripheral walls 21b, 21b of the flat tubes
21 that are placed at both ends of the second flow passage, an
upper wall portion (a second flow passage component) formed by the
peripheral wall 21b or a partition wall 21c, and a lower wall
portion formed by the peripheral wall 21b or the partition wall 21c
(a second flow passage component). Thus, the flat tube bundle 20
comprises a plurality of the second flow passages B1a, which
constitutes a second flow passage group B1.
[0147] The CPU 101 is installed in substantially center of the back
side (out side) of the bottom 11 (see FIG. 3). Thus, the heat of
the CPU 101 is transmitted to the peripheral walls 21b surrounding
the inner holes 21a (second flow passages B1a) of each of the flat
tubes and the partition walls 21c partitioning off the adjacent
inner holes 21a. Then, the heat transmitted to the peripheral walls
21b and the partition walls 21c (heat exchange portion) further
transmits to the coolant flowing through each of the second flow
passages. Thus, the CPU 101 mainly dissipates the heat to the
coolant flowing through the second flow passage group.
[0148] Because the flat tube bundle 20 is formed by bundling a
plurality of the flat tubes 21, the peripheral walls 21b (a heat
exchange portion) which directly dissipates the heat to the coolant
increase. As a result, the heat can be efficiently exchanged
between the CPU 101 and the coolant. Thus, the CPU 101 can be
efficiently cooled.
The First Flow Passage, the Second Flow Passage Group and the Third
Flow Passage
[0149] The first flow passage A1, the second flow passage group B1
(a plurality of second flow passages B1a) and the third flow
passage C1 are further described.
[0150] The first flow passage A1 is a flow passage to which the
coolant is supplied from the micro pump 122. The first flow passage
A1 is disposed on the side of the micro pump 122, which is upstream
of the second flow passage group. The second flow passage group B1
is disposed at downstream of the first flow passage A1, and each of
the second flow passages constituting the second flow passage group
B1 is branched from the first flow passage A1. Thus, the coolant is
distributed from the first flow passage A1 to flow into each of the
second flow passages. The third flow passage C1 is disposed
downstream of the second flow passage group B1, that is, downstream
of the plurality of the second flow passages. The third flow
passage C1 also collects the plurality of the second flow passages
B1a. Thus, the coolant flowing out of each of the second flow
passages B1a is collected by the third flow passage C1 and then
discharged from the liquid cooling jacket J1.
[0151] A cross-sectional area of the first flow passage A1 and the
third flow passage C1 is set to be larger than a cross-sectional
area of each of the second flow passages B1a. A length of each of
the second flow passages B1a (a length of each of the flat tubes
21) is remarkably shorter than that of only one flow passage
meandering through all parts of a flat tube bundle according to the
conventional art.
[0152] Thus, the coolant flowing through the first flow passage A1,
the second flow passages B1a and the third flow passage C1 in order
is not subjected to almost any pressure loss. The pressure loss of
the coolant in each of the second flow passages B1a is also
remarkably lower than a pressure loss that a coolant would receive
in the only one meandering flow passage. Thus, a declared power of
the micro pump 122 supplying the coolant to the liquid cooling
jacket J1 can be reduced. Accordingly, the micro pump 122 can be
small-sized and the noise thereof can be also reduced.
The Lid Unit
[0153] As shown in FIG. 7, the lid unit 30 (mainly) comprises a lid
body 31, an inlet pipe 32 and an outlet pipe 32.
The Lid Body
[0154] The lid body 31 is connected and fixed to the jacket body 10
as if a lid is put on the jacket body 10 accommodating the flat
tube bundle 20. An inlet 31a which communicates with the first flow
passage A1 (space 10a) and an outlet 31b which communicates with
the third flow passage C1 (space 10c) are formed on the lid body 31
(see FIG. 7).
[0155] The lid body 31 also comprises the notch 31c formed by being
cut out. The shape of the notch 31c corresponds to the fitting
portion 14 of the jacket body 10. Thus, the lid body 31 (lid unit
30) is combined with the jacket body 10 only in a predetermined
direction.
The Inlet and the Outlet
[0156] As shown in FIG. 5, the inlet 31a and outlet 31b are
arranged symmetric with respect to the CPU 101 in a plane view. The
inlet 31a and outlet 31b are also arranged relatively away from
each other in a plain view. In other words, the inlet 31a, outlet
31b and the CPU 101 are disposed on a diagonal line of the liquid
cooling jacket J1, which is square in a plane view. To be more
specific, the inlet 31a is disposed on an upper left side in FIG.
5, and the outlet 31b is disposed on a lower right side in FIG. 5
while the CPU 101 is disposed at approximately middle of the inlet
31a and outlet 31b (approximately center of the square liquid
cooling jacket). Thus, the coolant from the inlet pipe 32 is
supplied substantially evenly to the whole of the second flow
passage group B1 (the whole of the plurality of second flow
passages B1a) through the inlet 31a and the first flow passage A1.
Then, the heat is exchanged between (the whole of) the coolant
flowing through the whole of the second flow passage group B1 and
the CPU 101.
[0157] After that, the coolant flowing from the plurality of second
flow passages B1a is collected by the third flow passage C1. Then,
the coolant is discharged from the liquid cooling jacket J1 through
the outlet 31b and the outlet pipe 33.
The Inlet Pipe and the Outlet Pipe
[0158] The inlet pipe 32 is fixed at the lid body 31. Connected to
the inlet pipe 32 is a flexible tube 124 communicating with the
micro pump 122 (see FIG. 1) disposed upstream of the liquid cooling
jacket J1. The coolant from the micro pump 122 is supplied to the
first flow passage A1 via an inner hole of the inlet pipe 32 and
the inlet 31a.
[0159] The outlet pipe 33 is fixed at the lid body 31. Connected to
the outlet pipe 33 is a flexible tube 124 communicating with the
radiator 121 (see FIG. 1) disposed downstream of the liquid cooling
jacket J1. Then, the coolant is discharged from the liquid cooling
jacket J1 through the outlet 31b and the inner hole of outlet pipe
33.
[0160] The inlet pipe 32 and outlet pipe 33 are fixed on the top
surface of the lid body 31 such that the inlet pipe 32 and outlet
pipe 33 stand on the top surface of the lid body 31. Therefore, the
flexible tubes 124, 124 can be connected to the inlet pipe 32 and
the outlet pipe 33 only from the upper surface of liquid cooling
jacket J1. Thus, it is easy to pipe the flexible tubes 124, 124
(see FIG. 1) even in the personal computer 120 of which space is
limited.
Effects of the Liquid Cooling Jacket
[0161] Effects of the liquid cooling jacket J1 are now
described.
[0162] The CPU 101 starts to operate and heat up when the personal
computer 120 (see FIG. 1) is powered on. Then, the heat of the CPU
101 is transmitted to the bottom 11 of the jacket body 10 via the
heat dissipating sheet 102. The heat is further transmitted to the
peripheral walls 21b and the partition wall 21c of each of the flat
tubes 21 constituting the flat tube bundle. When the personal
computer 120 is powered on, the micro pump 122 also starts to
operate, and the coolant begins circulating. The coolant flows the
first flow passage A1, the second flow passage group B1 (the
plurality of the second flow passages B1a) and the third flow
passage C1 in order in the liquid cooling jacket J1.
[0163] Then, the heat is exchanged between the peripheral walls 21b
and the partition wall 21c of each of the flat tubes 21 and the
coolant flowing through the plurality of the second flow passages
B1a. The heat of the CPU 101 transmitted to the peripheral walls
21b and the partition wall 21c is further transmitted to the
coolant, and thus the coolant receives the heat.
[0164] The coolant having received the heat in each of the second
flow passages B1a is collected by the third flow passage C1 and
then discharged from the liquid cooling jacket J1 via the outlet
31b and the outlet pipe 33.
[0165] The discharged coolant is supplied to the radiator 121
through the flexible tube 124. The heat of the coolant is
dissipated in the radiator 121. The coolant of which temperature is
lowered flows into the micro pump 122 through the reserve tank 123
and flexible tube 124, and then supplied to the liquid cooling
jacket J1 again.
[0166] By repeating the processes of [0167] (1) Transmission of the
heat to the heat dissipating sheet 102, the bottom 11, the
peripheral walls 21b and the partition wall 21c of each of the flat
tubes 21, [0168] (2) Transmission of the heat to the coolant from
the peripheral walls 21b and the partition wall 21c, and [0169] (3)
Dissipation of the heat of the coolant in the radiator 121, the CPU
101 is efficiently cooled.
[0170] The heat of the CPU 101 is distributed to the peripheral
walls 21b and the partition wall 21c of the plurality of the flat
tubes 21. The heat of the peripheral walls 21b and the partition
wall 21c is further transmitted to the coolant flowing through each
of the plurality of the second flow passages B1a. Thus, the CPU 101
can be efficiently cooled.
[0171] Moreover, the coolant supplied to the liquid cooling jacket
J1 flows into the plurality of the second flow passages B1a (the
second flow passage group B1) which exchanges the heat, and has the
shorter passage length via the first flow passage A1 of which cross
sectional area is large. Then, the coolant is collected by the
third flow passage C1 having a large cross sectional area.
Therefore, the pressure loss the coolant is subjected to in the
liquid cooling jacket J1 becomes small. As a result, the micro pump
122 can be small sized and an applicable range of the liquid
cooling jacket J1 becomes wide.
[0172] Furthermore, in accordance with the liquid cooling jacket J1
(the present invention), the coolant can flow in smaller pressure
loss and higher flow rate, compared with the liquid cooling jacket
according to the conventional art, which comprises the only one
long meandering second flow passage as shown in FIG. 8. As shown in
FIG. 8, an intersection M2 of a pressure loss--flow rate curve
according to the present invention and a pressure loss--flow rate
curve of a micro pump is shifted right-ward compared to a
intersection M1 of a pressure loss--flow rate curve according to
the conventional art and the pressure loss--flow rate curve of the
micro pump. This indicates the pressure loss becomes small and the
flow rate becomes high in accordance with the present
invention.
Manufacture Method of the Liquid Cooling Jacket
[0173] A manufacture method of the liquid cooling jacket J1 is now
described with reference to FIG. 7. The manufacture method of the
liquid cooling jacket J1 mainly comprises steps of: a first step of
manufacturing the flat tube bundle 20, and a second step of bonding
and fixing the flat tube bundle 20 to the jacket body 10.
First Step
[0174] The plurality of the flat tubes 21 is connected and bundled
by an appropriate means. Then, both ends of the flat tubes bundled
are cut and grinded to manufacture the flat tube bundle 20.
Second Step
[0175] The flat tube bundle 20 is heat-exchangeably bonded and
fixed to the predetermined position of the bottom 11 of the jacket
body 10 by an appropriate means (fluxed with Al--Si--Zn brazing
filler material). The space 10a (first flow passage A1) and the
space 10c (third flow passage C1) are ensured to be left at both
ends of the flat tube bundle 20 when the flat tube bundle 20 is
fixed to the jacket body 10.
[0176] After that, the lid body 31 to which the inlet pipe 32 and
outlet pipe 33 are fixed at a predetermined position is connected
and fixed to the jacket body 10. Thus, the liquid cooling jacket J1
is obtained.
[0177] It is to be noted that the inlet pipe 32 and outlet pipe 33
may be fixed to the lid body 31 after the lid body 31 is fixed to
the jacket body 10.
[0178] As described above, in accordance with the manufacture
method of the liquid cooling jacket J1 according to the first
embodiment, the liquid cooling jacket J1 can be obtained by a
simple process of making the flat tube bundle 20 from the plurality
of the flat tubes 21, fixing the flat tube bundle 20 to the jacket
body 10, and fixing the lid body 31 to the jacket body 10.
Second Embodiment
[0179] A liquid cooling jacket according to a second embodiment is
now described with reference to FIG. 9 and FIG. 10. FIG. 9 is a
perspective view of a liquid cooling jacket J2 according to the
second embodiment, in which a lid unit is omitted.
FIG. 10 is a cross-sectional view of the liquid cooling jacket J2
according to the second embodiment along a line Y-Y shown in FIG.
9.
[0180] As shown in FIG. 9 and FIG. 10, the liquid cooling jacket J2
according to the second embodiment comprises a flat tube bundle 23
instead of the flat tube bundle 20 of the liquid cooling jacket J1
according to the first embodiment. Although the flat tube bundle 23
is the same as the flat tube bundle 20 in outside dimension, the
flat tube bundle 23 is formed by bundling a plurality of laminar
flat tubes 24 (three laminar flat tubes in FIG. 9 and FIG. 10).
Each of the flat tubes 24 comprises a plurality of inner holes (12
inner holes in FIG. 9 and FIG. 10) inside thereof. Each of the
inner holes is a second flow passage B2a. As a result, the flat
tube bundle 23 comprises a second flow passage group B2 including a
plurality of the second flow passages B2a.
[0181] Because each of the flat tubes 24 is laminar, the number of
the inner holes 24a bored in the flat tube 24 (12 inner holes in
FIG. 9) is larger than the number of the inner holes 21a bored in
the flat tube 21 (2 inner holes) according to the first embodiment.
Therefore, the number of the flat tubes 24 (3 flat tubes)
constituting the flat tube bundle 23 is less than the number of the
flat tubes 21 (20 flat tubes in FIG. 7) constituting the flat tube
bundle 20 according to the first embodiment. Thus, in accordance
with the flat tube bundle 23 according to the second embodiment,
the number of the flat tubes 24 to be bundled can be reduced
compared to that of the flat tube bundle 20 according to the first
embodiment. Thus, the flat tube bundle 23 can be easily
manufactured without much labor.
Third Embodiment
[0182] A liquid cooling jacket according to a third embodiment is
now described with reference to FIG. 11 and FIG. 12. FIG. 11 is a
perspective view of the liquid cooling jacket according to the
third embodiment. FIG. 12 is a plain view of the liquid cooling
jacket according to the third embodiment.
Configuration of the Liquid Cooling Jacket
[0183] As shown in FIG. 11 and FIG. 12, the liquid cooling jacket
J3 according to the third embodiment comprises a lid body 34 on
which an inlet 34a and an outlet 34b are disposed in positions
different from those of the liquid cooling jacket J1 according to
the first embodiment.
[0184] The inlet 34a communicates with substantially center of the
space 10a (first flow passage A1). The coolant is supplied to the
substantially center of the space 10a. The outlet 34b communicates
with substantially center of the space 10c (third flow passage C1).
The coolant is discharged from the substantially center of the
space 10c. The inlet 34a and outlet 34b are disposed symmetric with
respect to the CPU 101 in a plain view. The inlet 34a and the
outlet 34b are also arranged such that the inlet 34a and the outlet
34b come closer to the heating element in the plain view.
[0185] Similar to the lid body 31 according to the first
embodiment, the lid body 34 comprises a notch 34c of which shape
corresponds to the fitting portion 14 of the jacket body 10.
Effects of the Jacket Body
[0186] Effects of the liquid cooling jacket J3 are now briefly
described.
[0187] The coolant supplied to the first flow passage A1 from the
inlet 34a is easy to flow through second flow passages which are
close to the CPU 101. Thus, the heat can be efficiently exchanged
between the coolant and the CPU 101, and thus the CPU 101 can be
efficiently cooled.
Fourth Embodiment
[0188] A liquid cooling jacket according to a fourth embodiment is
now described with reference to FIG. 13 to FIG. 20. FIG. 13 is a
perspective view of the liquid cooling jacket according to the
fourth embodiment, in which a lid unit is omitted. FIG. 14 is a
cross-sectional view of the liquid cooling jacket according to the
fourth embodiment along a line Z-Z shown in FIG. 13. FIG. 15 is an
enlarged view of the cross-sectional view along the line Z-Z shown
in FIG. 14. FIG. 16 is a perspective view of a first manufacture
method of a fin member of the liquid cooling jacket according to
the fourth embodiment; FIG. 16A shows an extrusion before it is
cut; and FIG. 16B shows the fin member after the extrusion is cut.
FIG. 17 is a perspective view of a second manufacture method of a
fin member of the liquid cooling jacket according to the fourth
embodiment; FIG. 17A shows an extrusion before it is cut; and FIG.
17B shows the fin member after the extrusion is cut. FIG. 18 is a
perspective view showing a friction stir welding according to the
fourth embodiment. FIG. 19 is a cross-sectional view showing the
friction stir welding according to the fourth embodiment. FIG. 20
is a plain view showing movement of a tool to be used for the
friction stir welding.
Construction of the Liquid Cooling Jacket
[0189] As shown in FIG. 13 and FIG. 14, the liquid cooling jacket
according to the fourth embodiment comprises a fin member 25 formed
of aluminum or aluminum alloy instead of the flat tubes 20
according to the first embodiment.
[0190] The liquid cooling jacket according to the fourth embodiment
also comprises a fin housing for housing the fin member 25. The fin
housing is surrounded by the peripheral wall 12. The fin member 25
is fixed to the bottom 11 by brazing and housed in the fin housing.
The fin housing is sealed by putting the lid body 31 on an opening
of the jacket body 10 (see FIG. 14).
The Fin Member
[0191] As shown in FIG. 14, the fin member 25 comprises a base 25a
and a plurality of fins 25b extended from the base 25a. The base
25a is heat-exchangeably bonded and fixed to the bottom 11 of the
jacket body 10. Thus, the heat of the CPU 101 is transmitted to
each of the fins 25b via the heat dissipating sheet 102 and the
bottom 11. A top end of each of the fins 25b is in contact with a
back side of the lid body 31. Preferably, the base 25a and the
jacket body 10 are securely heat-exchangeably bonded by the brazing
filler material formed of Al--Si--Zn alloy.
[0192] An interval between the adjacent fins 25b, 25b is a second
flow passage B3a. That is, the fin member 25 comprises a second
flow passage group B3 comprising a plurality of the second flow
passages B3a. As shown in FIG. 15, the interval between the
adjacent fins 25b, 25b, or a groove width W1, which is a width of
the second flow passage B3a is designed to be 0.2 to 1.1 mm. In
accordance with this construction, thermal resistance of the liquid
cooling jacket and a pressure loss the coolant flowing inside
thereof is subjected to can be made to be within a preferable range
as shown in another embodiment, which is described later.
[0193] The groove width W1 and a thickness T1 of the fins 25b, or
the thickness T1 of the fins 25b disposed between the adjacent
second flow passages satisfy Formula 1 below.
-0.375.times.W+0.875.ltoreq.T1/W1.ltoreq.-1.875.times.W+3.275
Formula 1
[0194] Thus, the thermal resistance of the liquid cooling jacket J4
becomes small, and the heat can be efficiently exchanged between
the CPU 101 and the coolant.
[0195] In addition, the groove width W1 and a depth D1 (a depth of
the second flow passage B3a) satisfy Formula 2 below.
5.times.W+1.ltoreq.D1.ltoreq.-16.25.times.W+2.75 Formula 2
Thus, the thermal resistance of the liquid cooling jacket J4
becomes optimum.
Effects of the Liquid Cooling Jacket
[0196] Effects of the liquid cooling jacket J4 are now briefly
described.
[0197] The coolant flows through the first flow passage A1, the
second flow passage group B3 (the plurality of second flow passages
B3a) and the third flow passage C1 in order. The heat is exchanged
between the coolant flowing through the second flow passage group
B3 and the plurality of fins 25b. Thus, the CPU 101 can be
efficiently cooled.
Manufacture Methods of the Fin Member of the Liquid Cooling
Jacket
[0198] Manufacture methods of the fin member 25 of the liquid
cooling jacket J4 are illustrated below.
First Manufacture Method of the Fin Member
[0199] A first manufacture method of the fin member 25 is described
with reference to FIG. 16. As shown in FIG. 16A, a metallic
extrusion 41 comprising a bottom plate 42, and a plurality of
protruded lines 43 extended from the bottom plate 42 is
manufactured by using a predetermined mold. Then, by cutting the
extrusion 41 in predetermined cutting surfaces, the fin member 25
comprising the base 25a (a part of the bottom plate 42), and a
plurality of fins 25b (a part of the plurality of the protruded
lines 43) can be manufactured.
Second Manufacture Method of the Fin Member
[0200] A second manufacture method of the fin member 25 is
described with reference to FIG. 17. As shown in FIG. 17A, a
plurality of grooves 44a is formed on a metallic block of which
shape corresponds to the dimension of the fin member 25 by using an
appropriate cutting tool. Thus, the fin member 25 comprising the
base 25a, and the plurality of fins 25b can be manufactured (see
FIG. 17B).
Assembling of the Liquid Cooling Jacket
[0201] A friction stir welding of the jacket body 10 to which the
fin member 25 is attached and the lid unit 30 is described below
with reference to FIG. 18 to FIG. 20.
[0202] As shown in FIG. 18, the lid unit 30 is put on the jacket
body 10 to which the fin member 25 is brazed with the notch 31c fit
to the fitting portion 14. As shown in FIG. 19, an opening end of
the jacket body 10 is uneven, and the lid body 31 is put on a step
portion 15 which is lowered by one step. A width W11 of the step
portion 15 is preferably set to be as narrow as possible so that a
volume of the first flow passage A1 and the third flow passage C1
through which the coolant flows is ensured to be left. To be more
specific, the width W11 is preferably set to be 0.1 to 0.5 mm.
[0203] A contact area P1 of the peripheral wall 12 and the lid body
31 is friction stir welded by using a tool 200 for the friction
stir welding. When the contact area P1 is friction stir welded, a
friction stir welded portion K (see FIG. 15) is formed in a
rearward of the tool 200, and the peripheral wall 12 and the lid
body 31 are connected. A length L5 of a pin 201 of the tool 200 is
preferably set to be less than or equal to 60% of a thickness T2 of
the lid body 31, which is a member to be connected. By making the
length L5 of the pin 201 of the tool 200 to be less than or equal
to 60% of the thickness T2, it is difficult for the contact area P1
to be protruded into inside of the jacket body 10 by a pressing
force of the tool 200, even if the width W11 of the step portion 15
is small, though it depends on a quality of material.
[0204] The tool 200 is controlled by a machine (not shown) such
that the tool 200 rotates and moves along the contact area P1 (see
FIG. 18).
[0205] When the contact area P1 is friction stir welded, an outer
surface of the peripheral wall 12 of the jacket body 10 is held by
an appropriate jig 210. This makes it difficult for the peripheral
wall 12 to be protruded outward by the pressing force of the tool
200 even if the peripheral wall 12 is thin and a length L6 between
the outer surface of the peripheral wall 12 and an outer surface of
the tool 200 is less than or equal to 2.0 mm for example.
[0206] In addition to this, a top surface of the jig 210 is
preferably lowered from a surface of the contact area P1 by
approximately 1.0 to 2.0 mm to keep the tool 200 from contact with
the jig 210 when the peripheral wall 12 is thin.
[0207] As shown in FIG. 20, the tool 200 is moved so that a start
end of the area which is friction stir welded overlaps with a
finish end of the area which is friction stir welded (see reference
symbol Q). Thus, the peripheral wall of the jacket body 10 is
securely connected with the lid body 31. This makes it difficult
for the coolant to leak. Then, the pin 201 is pulled apart after
the tool 200 is removed from the contact area P1. Thus, a trace
which would be made when pulling the pin 201 apart is not formed on
the contact area P1.
Fifth Embodiment
[0208] A liquid cooling jacket according to a fifth embodiment is
now described with reference to FIG. 21 to FIG. 25. FIG. 21 is a
cross-sectional view of the liquid cooling jacket according to the
fifth embodiment. FIG. 22 is an enlarged view of the
cross-sectional view shown in FIG. 21. FIG. 23 is a perspective
view of a manufacture method of a fin member of the liquid cooling
jacket according to the fifth embodiment; FIG. 23A shows the fin
member during a skive process; and FIG. 23B shows the fin member
after the skive process has completed. FIG. 24 is a view showing
the manufacture method of the fin member of the liquid cooling
jacket according to the fifth embodiment, illustrating the fin
member after parts of the skive fins shown in FIG. 23 are removed.
FIG. 25 is a cross-sectional view showing a friction stir welding
according to the fifth embodiment.
[0209] Different features of the liquid cooling jacket according to
the fifth embodiment compared with the liquid cooling jacket J4
according to the fourth embodiment are described below.
Construction of the Liquid Cooling Jacket
[0210] As shown in FIG. 21, a liquid cooling jacket J5 according to
the fifth embodiment comprises a jacket body 10C and a fin member
29 formed of aluminum or aluminum alloy, wherein the CPU 101 is
installed on a bottom 29a (sealing member) of the fin member
29.
[0211] The jacket body 10C is a laminar box which opens to downside
of FIG. 21 and comprises a fin housing inside of the laminar
box.
[0212] As described later, the fin member 29 is formed by skiving a
plate 61 (see FIG. 23A). The fin member 29 comprises the bottom 29a
and a plurality of metallic fins 29b. The plurality of fins 29 are
extended from the bottom 29a and integrally formed with the bottom
29a. Thus, the heat is efficiently transmitted between the bottom
29a and the fins 29b.
[0213] The bottom 29a has a function of a sealing member for
sealing the fin housing. Furthermore, an interval between the
adjacent fins 29b, 29b has a function of a second flow passage B4a
(see FIG. 22). The liquid cooling jacket J5 comprises a second flow
passage group B4 constituted by a plurality of the second flow
passages B4a. Similar to the fourth embodiment, when the fin member
29 is extended from the jacket body 10C, the first flow passage A1
and the third flow passage C1 are formed in the liquid cooling
jacket J5 (see FIG. 13).
Effects of the Liquid Cooling Jacket
[0214] Effects of the liquid cooling jacket J5 are now briefly
described.
[0215] The coolant flows through the first flow passage A1, the
second flow passage group B4 (the plurality of second flow passages
B4a) and the third flow passage C1 in order. The heat is mainly
exchanged between the coolant flowing through the second flow
passage group B4 and the plurality of fins 29b. Thus, the CPU 101
can be efficiently cooled. Because the bottom 29a and the fins 29b
are integrally formed, the heat of the CPU 101 is efficiently
transmitted to the plurality of the fins 29b. This makes it
possible to radiate the heat efficiently.
Manufacture Method of the Fin Member of the Liquid Cooling
Jacket
[0216] A manufacture method of the fin member 29 of the liquid
cooling jacket J5 using skive process is described with reference
to FIG. 23 and FIG. 24. As shown in FIG. 23A, a plate-like plate 61
is skived as described in Japanese Laid-open Patent Application No.
2001-326308 and Japanese Laid-open Patent Application No.
2001-352020. To be more specific, the plate 61 is cut by a cutting
tool 62 in an acute angle to open up parts of the plate 61. Thus, a
plurality of skive fins 63 is formed. By repeating the above
process, a skive fin intermediate 64 comprising the plurality of
skive fins 63 is manufactured (see FIG. 23B). Parts of the plate 61
which are not opened up are the bottom 29a of the fin member
29.
[0217] Then, outer sides of the plurality of skive fins 63 are cut
by a cutting tool so that the first flow passage A1 and the third
flow passage C1 are formed in the liquid cooling jacket J5 when the
fin member 29 and the jacket body 10c are combined to form the
liquid cooling jacket J5. Thus, the fin member 29 comprising the
bottom 29a and the plurality of fins 29b integrally formed on the
bottom 29 is obtained.
[0218] Manufacture methods of the fin member 29 are not limited to
the above method. The fin member 29 may be obtained by removing
parts of the fins 25b of the fin member 25 formed by cutting the
extrusion 41 according to the fourth embodiment (see FIG. 16), or
by removing parts of the fins 25b of the fin member 25 formed by
grooving (see FIG. 17).
Assembling of the Liquid Cooling Jacket
[0219] As shown in FIG. 25, similar to the fourth embodiment, the
jacket body 10c and the fin member 29 is combined and a contact
area P2 is friction stir welded with the jig 210 holding the jacket
body 10C. The length L5 of the pin 201 of the tool 200 is less than
or equal to 60% of a thickness T3 of the bottom 29a (sealing
member) of the fin member 29 which is a member to be connected.
Sixth Embodiment
[0220] A liquid cooling jacket according to a sixth embodiment is
now described with reference to FIG. 26. FIG. 26 is a
cross-sectional view of the liquid cooling jacket according to the
sixth embodiment; FIG. 26A shows the liquid cooling jacket after
assembled; and FIG. 26B shows the liquid cooling jacket before
assembled.
Construction of the Liquid Cooling Jacket
[0221] As shown in FIG. 26A, the liquid cooling jacket J6 according
to the sixth embodiment comprises a jacket body 10A (first fin
member) and a lid unit 35 (second fin member) compared with the
liquid cooling jacket J1 according to the first embodiment. The
jacket body 10A comprises a bottom 11 (first base) and a plurality
of fins 13 extended from the bottom 11 at a predetermined interval.
The lid unit 35 comprises a lid body 36 (second base) and a
plurality of fins 37 extended from the lid body 36 at a
predetermined interval.
[0222] The jacket body 10A and the lid unit 35 are combined such
that the plurality of fins 13 and the plurality of fins 37
interlock together. The lid unit 35 is connected and fixed to the
jacket body 10A. The whole of fins of the liquid cooling jacket J6
is constituted by the plurality of fins 13 and 37 interlocked
together. An interval between the adjacent fins 13 and 37 is a
second flow passage B5a, and the liquid cooling jacket J6 comprises
a second flow passage group B5 comprising a plurality of second
flow passages B5a.
[0223] Thus, because the whole of fins is formed by interlocking
the plurality of fins 13 and 37 together, an interval d1 between
the adjacent fins 13 and an interval d2 between the adjacent fins
37 can be made wide, which makes the groove process using the
cutting tool and the like easier.
[0224] A protruding length L1 of the plurality of fins 13 from the
bottom 11 is set to be equal to or shorter than a protruding length
L2 of the plurality of fins 37 from the lid body 36 as shown in
FIG. 26B. The plurality of fins 37 are heat-exchangeably bonded and
fixed to the bottom 11 by an appropriate means, and also thermally
connected to the bottom 11. Thus, the heat of the CPU 101 on a side
of the jacket body 10A (first base) is transmitted not only to the
plurality of fins 13, but also to the plurality of fins 37.
[0225] That is, because the protruding length L1 of the plurality
of fins 13 is set to be equal to or shorter than the protruding
length L2 of the plurality of fins 37, top ends of the plurality of
fins 37 are ensured to come into contact with the bottom 11 of the
jacket 10A. Thus, the plurality of fins 37 and the bottom 11 are
ensured to be thermally connected.
Effects of the Liquid Cooling Jacket
[0226] Effects of the liquid cooling jacket J6 are now briefly
described.
[0227] In accordance with the liquid cooling jacket J6, when the
coolant flows through the second flow passage group B5, the heat
transmitted to the plurality of fins 13 and the plurality of fins
37 is further transmitted to the flowing coolant. Thus, the CPU 101
can be efficiently cooled.
Seventh Embodiment
[0228] A liquid cooling jacket according to a seventh embodiment is
now described with reference to FIG. 27. FIG. 27 is a
cross-sectional view of the liquid cooling jacket according to the
seventh embodiment; FIG. 27A shows the complete liquid cooling
jacket after assembled; and FIG. 27B shows the liquid cooling
jacket before assembled.
Construction of the Liquid Cooling Jacket
[0229] As shown in FIG. 27A and FIG. 27B, the liquid cooling jacket
J7 according to the seventh embodiment comprises a metallic
honeycomb member 26 comprising a plurality of minute holes 26a
instead of the flat tube bundle 20 of the liquid cooling jacket J1
according to the first embodiment.
The Honeycomb Member
[0230] The honeycomb member 26 is heat-exchangeably bonded and
fixed to the bottom 11 of the jacket body 10 by an appropriate
means. Therefore, the heat of the CPU 101 is transmitted to
peripheral wall 26b surrounding the minute holes 26a. Each of the
minute holes has a function of a second flow passage B6a, through
which the coolant flows. That is, the honeycomb member 26 comprises
a second flow passage group B6 comprising a plurality of the second
flow passages B6a. Although the honeycomb member 26 comprises the
plurality of minute holes 26a, each of which is rectangular in
cross sectional view is illustrated in FIG. 27, a shape of the
minute holes 26a is not limited to this and may be other shapes
such as hexagon. Preferably, the honeycomb member 26 and the bottom
11 of the jacket 10 are securely heat exchangeably bonded together
by the brazing filler metal.
Effects of the Liquid Cooling Jacket
[0231] Effects of the liquid cooling jacket J7 are now briefly
described.
[0232] The coolant flows through the first flow passage A1, the
second flow passage group B6 (the plurality of second flow passages
B6a) and the third flow passage C1 in order. The heat is mainly
exchanged between the peripheral wall 26b of the honeycomb member
26 and the coolant flowing through the second flow passage group
B6. The heat of the peripheral wall 26b is transmitted to the
coolant as described above. Thus, the CPU 101 can be efficiently
cooled.
Eighth Embodiment
[0233] A liquid cooling jacket according to an eighth embodiment is
now described with reference to FIG. 28. FIG. 28 is a
cross-sectional view of the liquid cooling jacket according to the
eighth embodiment; FIG. 28A shows the complete liquid cooling
jacket after assembled; and FIG. 28B shows the liquid cooling
jacket before assembled.
Construction of the Liquid Cooling Jacket
[0234] As shown in FIG. 28A and FIG. 28B, the liquid cooling jacket
J8 according to the eighth embodiment comprises a ripple
cross-section metallic heat dissipating sheet 27 (brazing sheet)
instead of the flat tube bundle 20 of the liquid cooling jacket J1
according to the first embodiment.
The Heat Dissipating Sheet
[0235] The heat dissipating sheet 27 comprises a sheet body 27a
formed of Al--Mn alloy and Al--Fn--Mn alloy and the like, a brazing
filler metal layer 27b formed of Al--Si--Zn alloy on the lower side
surface of the sheet body 27a. A part of the brazing filler metal
layer 27b is molten and then cured so that the heat dissipating
sheet 27 is heat-exchangeably bonded and fixed to the bottom 11 of
the jacket body 10. Thus, the heat of the CPU 101 is transmitted to
the heat dissipating sheet 27 via the bottom 11.
[0236] A plurality of second flow passages B7a is formed between
the heat dissipating sheet 27 and the jacket body 10 and also
between the heat dissipating sheet 27 and the lid body 31. That is,
the liquid cooling jacket J8 comprises a second flow passage group
B7 comprising a plurality of the second flow passages B7a.
Effects of the Liquid Cooling Jacket
[0237] Effects of the liquid cooling jacket J8 are now briefly
described.
[0238] The coolant flows through the first flow passage A1, the
second flow passage group B7 (the plurality of second flow passages
B7a) and the third flow passage C1 in order. The heat is mainly
exchanged between the heat dissipating sheet 27 and the coolant
flowing through the second flow passages B7a. Thus, the heat of the
heat dissipating sheet 27 is transmitted to the coolant. As a
result, the heat of the CPU 101 is efficiently cooled.
Ninth Embodiment
[0239] A liquid cooling jacket according to a ninth embodiment is
now described with reference to FIG. 29. FIG. 29 is a plane view of
the liquid cooling jacket according to the ninth embodiment. FIG.
29 illustrates the liquid cooling jacket without a lid body for an
explanatory purpose.
Construction of the Liquid Cooling Jacket
[0240] As shown in FIG. 29, although the liquid cooling jacket J1
according to the first embodiment comprises the flat tube bundle
20, the liquid cooling jacket J9 according to the ninth embodiment
comprises three flat tube bundles 20. The three flat tube bundles
20 are disposed in line such that the inner holes 21a (second flow
passage B1a) of each flat tube bundle 20 face in the same direction
in a jacket body 10B. The three flat tube bundles 20 are also
heat-exchangeably bonded and fixed to the bottom 11 of the jacket
body 10B while a space 10d between the upstream flat tube bundle 20
and the midstream flat tube bundle 20 and a space 10d between the
midstream flat tube bundle 20 and the downstream flat tube bundle
20 are provided in the jacket body 10B.
[0241] The spaces 10d, 10d have a function of a fourth flow passage
E1, E1 (communication flow passage) connecting the second flow
passage groups B1, which are the flat tube bundles, in-line. A
cross-sectional area of the fourth flow passage E1 is set to be
larger than the cross-sectional area of the second flow passage B1a
constituting each second flow passage group. The liquid cooling
jacket J9 according to the ninth embodiment comprises three second
flow passage groups B1, B1, B1 (second flow passage group portion)
disposed in line.
Effects of the Liquid Cooling Jacket
[0242] Effects of the liquid cooling jacket J9 are now briefly
described.
[0243] The coolant flows through the first flow passage A1, the
upstream second flow passage group B1, the fourth flow passage E1,
the midstream second flow passage group B1, the fourth flow passage
E1, and the third flow passage C1 in order. That is, the coolant
flows through three second flow passage groups B1, B1, B1 in line.
At that time, the pressure loss the coolant is subjected to in the
fourth flow passage E1 becomes small because the coolant flows
through the fourth flow passage E1 between the adjacent second flow
passage groups B1, B1. In other words, a load applied to the micro
pump 122 can be made smaller by disposing the fourth flow passage
E1 which has the large cross sectional area between the second flow
passage groups B1, B1, compared to the long second flow passage
group without the fourth flow passages E1.
Tenth Embodiment
[0244] A liquid cooling jacket according to a tenth embodiment is
now described with reference to FIG. 30 and FIG. 31. FIG. 30 is a
plane view of the liquid cooling jacket according to the tenth
embodiment. FIG. 31 is a graph showing a relationship between the
number of second flow passage groups and the thermal
resistance.
[0245] As shown in FIG. 30, similar to the liquid cooling jacket J9
according to the ninth embodiment, the liquid cooling jacket J10
according to the tenth embodiment comprises the three second flow
passage groups B1, B1, B1 (second flow passage group portion)
connected in series, wherein the adjacent second flow passage
groups B1, B1 are connected in series in a coolant flowing
direction via the fourth flow passage E1 (communication flow
passage).
[0246] In the liquid cooling jacket J10, however, the adjacent
second flow passages B1, B1 are disposed side by side such that a
downstream end of the upper second flow passage B1 of the adjacent
second flow passages B1, B1 and an upstream end of the lower second
flow passage B1 of the adjacent second flow passages B1, B1 are
disposed on the same side. The downstream end and the upstream end
are connected in series via the fourth flow passage E1. To be more
specific, the upstream second flow passage B1 and the midstream
second flow passage B1 are disposed side by side in the coolant
flowing direction and also in the lateral direction of FIG. 30. For
example, a downstream end of the upstream second flow passage B1
and an upstream end of the midstream second flow passage B1 face
toward the same side, which is a downside in FIG. 30.
[0247] In this specification, the state where the adjacent second
flow passages B1, B1 are disposed side by side as described above
is represented as "coolant is turned" in contrast to the ninth
embodiment.
[0248] In accordance with the liquid cooling jacket J10, the
coolant meanders in the liquid cooling jacket J10. This makes the
thermal resistance of the liquid cooling jacket J10 to be smaller
than that of the liquid cooling jacket J9 according to the ninth
embodiment.
[0249] More specifically, when the size of the liquid cooling
jacket in a plain view is constant, if the number of the second
flow passages is increased by increasing the number of times the
coolant is turned without changing the number of the second flow
passages constituting each of the second passage groups, a
cross-sectional area of each of the second flow passages
constituting each of the second flow passage groups becomes
smaller. Therefore, when the flow rate of the coolant flowing
through the liquid cooling jacket is constant, if the number of the
second flow passage groups is increased, a flow speed of the
coolant in each of the second flow passages is increased. Thus, the
heat is efficiently transmitted from the liquid cooling jacket to
the coolant, and the thermal resistance of the liquid cooling
jacket decreases accordingly.
[0250] The preferred embodiments of the present invention have been
described above. However, the present invention is not limited to
the above embodiments, and the various embodiments may be combined
as appropriate as long as it does not deviate from the spirit of
the present invention. For example, the embodiments of the present
invention may be modified as described below.
[0251] The description has been made on the case where the heating
element is the CPU 101 in each of the above embodiments; however,
types of the heating element are not limited to a CPU and may be a
power module, LED lamp, and the like for example.
[0252] The description has been made on the case where the flat
tube bundle 20 is formed by the plurality of flat tubes 21 bundled
in a thickness direction in the first embodiment, however, the flat
tubes 21 may be further bundled in a width direction.
[0253] The description has been made on the case where the liquid
cooling jacket J1 according to the first embodiment comprises the
flat tube bundle 20 formed by the plurality of the flat tubes 21
bundled (see FIG. 6). As shown in FIG. 32, however, the liquid
cooling jacket may be a liquid cooling jacket J11 comprising a flat
tube 28 having a plurality of inner holes 28a partitioned by a
plurality of partition walls, instead of the flat tube bundle 20.
In this case, each of the plurality of inner holes 28a has a
function of a second flow passage B8a, and the flat tube 28
comprises a second flow passage group B8 comprising a plurality of
the second flow passages B8a.
[0254] The description has been made on the case where the inlet
31a and the outlet 31b are installed on the lid body 31 in the
liquid cooling jacket J1 according to the first embodiment.
However, positions of the inlet 31a and the outlet 31b are not
limited to this, and the inlet 31a and the outlet 31b may be
installed on the peripheral wall 12 of the jacket body 10 for
example. Furthermore, positions of the inlet pipe 32 and the outlet
pipe 33 are also not limited to the upper surface of the liquid
cooling jacket J1, and may be on the side surface of the liquid
cooling jacket J1.
[0255] The description has been made on the case where the fins 13
are extended from the jacket body 10A and the fins 37 are extended
from the lid body 37 in the liquid cooling jacket J6 according to
the sixth embodiment (see FIG. 26). As shown in FIG. 33A and FIG.
33B, however, the liquid cooling jacket may be a liquid cooling
jacket J12 comprising a first fin member 50 comprising a first base
51 and a plurality of first fins 52 extended from the first base
51, and a second fin member 55 comprising a second base 56 and a
plurality of second fins 57 extended from the second base 56.
[0256] The liquid cooling jacket J12 shown in FIG. 33 is further
described below. The first fin member 50 and the second fin member
55 are combined such that the plurality of the first fins 52 and
the plurality of the second fins 57 are interlocked together. The
whole of the plurality of the metallic fins in the liquid cooling
jacket J12 is constituted by the plurality of the first fins 52 and
the plurality of the second fins 57. The second flow passage B9a is
formed between the first fin 52 and the second fin 57 adjacent to
each other. The first fin member 50 is disposed on a side of the
CPU 101 and the first base 51 is heat-exchangeably fixed to the
bottom 11 of the jacket body 10.
[0257] The liquid cooling jacket J12 comprises a second flow
passage group B9 comprising a plurality of the second flow passages
B9a. A protruding length L3 of the plurality of the first fins 52
from the first base 51 is set to be equal to or shorter than a
protruding length L4 of the plurality of the second fins 57 from
the second base 56. The plurality of the second fins 57 and the
first base 51 are heat exchangeably-bonded and fixed by an
appropriate means, and thus thermally connected to each other.
[0258] The first flow passage A1 and the third flow passage C1 are
formed by the space 10a and the space 10c provided between the
jacket body 10 and the flat tube bundle 20 in the first embodiment
(see FIG. 5). However, a branched tube, of which inner holes are
first flow passages, may be disposed outside and upstream of the
jacket body 10, and a collecting tube, of which inner holes are
third flow passages, may be disposed downstream.
[0259] The fin member 25 is fixed to the jacket body 10 in the
liquid cooling jacket J4 according to the fourth embodiment (see
FIG. 14). As shown in FIG. 34, however, the liquid cooling jacket
may be a liquid cooling jacket J13 wherein the fin member 25 is
fixed to a side of the lid body 31 which faces to the jacket body
10. As shown in FIG. 34, the CPU 101 may be installed on the lid
body 31. Furthermore, the inlet pipe 32 which is used as a coolant
inlet of the liquid cooling jacket J13 and the outlet pipe 33 which
is used as a coolant outlet may be installed on the jacket body 10.
In addition to this, the fins may be integrally formed with the
side of the lid body 31 which faces to the jacket body 10.
[0260] Further, as shown in FIG. 35, when the jacket body 10
comprises four legs 16, each of which comprises an insertion hole
16a through which a screw 125 is inserted, and the liquid cooling
jacket J13 is installed in a casing 126 of the personal computer
120 (see FIG. 1), a position where the tool 200 is pulled apart is
preferably a portion corresponding to the insertion hole 16a. After
the tool 200 is pulled apart from the part described above, the
insertion hole 16a is bored in the portion where the tool 200 is
pulled apart. Thus, a trace of the pin which is pulled apart does
not remain.
[0261] FIG. 34 is a cross-sectional view along a line X1-X1 in FIG.
35.
EXAMPLES
[0262] The present invention is described more specifically based
on examples below.
Example 1
[0263] Analysis of the Groove Width W1 of the Second Flow Passage
B3a
[0264] In the liquid cooling jacket J4 according to the fourth
embodiment (see FIG. 13), aluminum alloy members wherein the groove
width W1 (see FIG. 15) of the second flow passage B3a is 0.2 mm,
0.5 mm and 1.0 mm are manufactured. Specification of the liquid
cooling jacket J4 is shown in Table 1.
[0265] An overall flow passage width W0 represents the width of the
first flow passage A1 and the third flow passage C1 in Table 1. An
overall length L0 represents a sum of the length of the first flow
passage A1, the length of the second flow passage B3a and the
length of the third flow passage C1 in Table 1 (see FIG. 13 and
FIG. 14).
TABLE-US-00001 TABLE 1 Heat conductivity of aluminum alloy (W/mk)
200 Overall flow passage width (mm) 100 Overall flow passage length
(mm) 100 Groove width of the second flow passage B3a (mm) 0.2, 0.5,
1.0 Depth of the second flow passage B3a (mm) 10
[0266] Water is used as the coolant. A relationship between the
groove width W1 and the thermal resistance of the liquid cooling
jacket J4, and a relationship between the groove width W1 and the
pressure loss of the liquid cooling jacket J4 are analyzed when the
micro pump 122 (see FIG. 1) is operated (see FIG. 2) such that the
water flows at 5 (L/min). The thermal resistance and the pressure
loss are measured by an appropriate means. In the liquid cooling
jacket J4 of this specification, a target thermal resistance is
less than or equal to 0.008 (degree/W).
TABLE-US-00002 TABLE 2 Coolant Water Flow rate of coolant (L/min)
5.0
[0267] As shown in FIG. 36, a contact area of the liquid cooling
jacket J4 and the coolant becomes larger as the groove width W1 of
the second flow passage B3a becomes smaller. Therefore, the thermal
resistance of the liquid cooling jacket J4 also becomes smaller as
the groove width W1 of the second flow passage B3a becomes smaller.
When the groove width W1 of the second flow passage B3a becomes
larger than 1.1 mm, the thermal resistance exceeds 0.08 (degree/W),
which is the target thermal resistance.
[0268] The pressure loss the coolant is subjected to becomes larger
than 5 (Pa) when the groove width W1 of the second flow passage B3a
becomes smaller than 0.2 mm.
[0269] Thus, the groove width W1 of the second flow passage B3a is
preferably within the range of 0.2 to 1.1 mm.
Example 2
Analysis of a Relationship Between the Thickness T1 of the Fin 25b
and the Groove Width W1
[0270] Similar to the example 1, the groove width W1 of the second
flow passage B3a is set to be 0.2 mm, 0.5 mm, and 1.0 mm (see Table
1). Then, the thickness T1 of the fins 25b is changed as
appropriate in each of the groove with W1 of the second flow
passage B3a. Thus, a relationship between "a ratio between the
thickness T1 of the fins 25b and the groove with W1 (T1/W1)" and
"the thermal resistance" is analyzed.
[0271] As shown in FIG. 37, there is a range of T1/W1 in which the
thermal resistance becomes small in each groove width W1. Within
the range, the thermal resistance is smaller than or equal to 105%
of the minimum thermal resistance in each groove width W1.
[0272] To be more specific, when the groove width W1 of the second
flow passage B3a is 1.0 mm, the minimum thermal resistance is
0.0073 (degree/W), and thus, 105% of the minimum thermal resistance
is 0.0076 (degree/W). The range in which the thermal resistance is
smaller than or equal to 0.0076 (degree/W) is
0.5.ltoreq.T1/W1.ltoreq.1.4.
[0273] Similar to this, when the groove width W1 of the second flow
passage B3a is 0.5 mm, the range is 0.7.ltoreq.T1/W1.ltoreq.2.1.
When the groove width W1 of the second flow passage B3a is 0.2 mm,
the range is 0.8.ltoreq.T1/W1.ltoreq.2.9.
[0274] A graph shown in FIG. 38 is obtained when "the groove width
W1" is represented by the x axis and "the fin thickness T1/the
groove width W1" is represented by the y axis on the basis of the
analysis above. As shown in FIG. 38, it is verified that "the
groove width W1" and "the fin thickness T1/the groove width W1"
preferably satisfy the Formula 1.
-0.375.times.W1+0.875.ltoreq.T1/W1.ltoreq.-1.875.times.W1+3.275
Formula 1
Example 3
Analysis of a Relationship Between the Groove Width W1 of the
Second Flow Passage B3a and the Depth D1 Thereof
[0275] In the liquid cooling jacket J4 according to the fourth
embodiment, the groove width W1 of the second flow passage B3a is
set to be 0.2 mm, 0.5 mm, and 1.0 mm (see Table 1). Then, the depth
D1 of the fins 25b is changed as appropriate in each of the groove
with W1 of the second flow passage B3a. Thus, a relationship
between "the depth D1" and "the thermal resistance" is
analyzed.
[0276] As shown in FIG. 39, similar to the example 2, it is
verified that there is a range of the depth D1 in which the thermal
resistance is small. The ranges are calculated similarly to the
example 2. When the groove width W1 of the second flow passage B3a
is 0.2 mm, the range is 2.ltoreq.D1.ltoreq.6. When the groove width
W1 of the second flow passage B3a is 0.5 mm, the range is
4.ltoreq.D1.ltoreq.11. When the groove width W1 of the second flow
passage B3a is 1.0 mm, the range is 6.ltoreq.D1.ltoreq.18.
[0277] A graph shown in FIG. 40 is obtained when "the groove width
W1" is represented by the x axis and "the depth D1" is represented
by the y axis on the basis of the analysis above. As shown in FIG.
40, it is verified that "the groove width W1" and "the depth D1"
preferably satisfy Formula 2.
5.times.W+1.ltoreq.D.ltoreq.-16.25.times.W+2.75 Formula 2
Example 4
Analysis of an Efficacy of the Jig
[0278] An efficacy of the jig 210 holding the peripheral wall 12 of
the jacket body 10 in the friction stir welding of the jacket body
10 and the lid body 31 according to the fourth embodiment is
analyzed. In this analysis, two types of the tools 200 shown in
Table 3 are used. As shown in Table 4, a length L6 between outer
surfaces of shoulders 202 of tool A and tool B and the outer
surface of the peripheral wall 12 of the jacket body 10 is changed
(see FIG. 19). Then, the peripheral wall 12 and the lid body 31 are
friction stir welded with or without the jig 210. The quality of
the connected portion is evaluated visually. .largecircle.
indicates a good connection, and x indicates a bad connection in
the following tables.
[0279] The number of revolutions of the tools 200 is 6000 rpm, and
a connection speed is 200 mm/min. A thickness T11 of the peripheral
wall 12 is 4 mm (see FIG. 19).
TABLE-US-00003 TABLE 3 Tool A Tool B Diameter of shoulder (mm) 6.0
8.0 Diameter of pin (mm) 2.5 3.0 Length of pin (mm) 2.0 2.0
TABLE-US-00004 TABLE 4 Quality of connection Tool Length L6 (mm)
Jig portion Tool A 1.0 Employed .smallcircle. Tool A 0.5 Employed
.smallcircle. Tool B 0.0 Employed x Tool A 1.0 Not employed x
[0280] As shown in Table 4, it is verified that the lid body 31 can
be connected in good quality without changing the peripheral wall
12 in shape when the jig 210 is employed, even if the peripheral
wall 12 is thin and the length L6 is 0.5 mm.
Example 5
A Relationship Between a Pin Length L5 and a Thickness T2 of the
Lid Body 31
[0281] A relationship between a length of a pin 201 of the tool 200
and a thickness T2 of the lid body 31 is analyzed. As shown in
Table 5, the length L5 of the pin 201 is a constant value of 2.0 mm
and the thickness T2 of the lid body 31 is changed in this
analysis. Then, the quality of the connection portion is visually
evaluated.
TABLE-US-00005 TABLE 5 Quality of Length L5 of Thickness T2 of
connection pin (mm) the lid body (mm) L5/T2 (%) portion 2.0 6.0
33.3 .smallcircle. 2.0 5.0 40.0 .smallcircle. 2.0 4.0 50.0
.smallcircle. 2.0 3.0 66.6 x
[0282] As shown in Table 5, it is verified that the peripheral wall
12 and the lid body 31 can be connected in good quality within the
range in which the length L5 of the pin 201 is smaller than or
equal to 60.0% of the thickness T2 of the lid body 31, which is a
member to be connected.
* * * * *