U.S. patent application number 14/370185 was filed with the patent office on 2014-12-18 for cooling device.
The applicant listed for this patent is Masaki CHIBA, Kenichi INABA, Arihiro MATSUNAGA, NEC Corporation, Hitoshi SAKAMOTO, Akira SHOUJIGUCHI, Minoru YOSHIKAWA. Invention is credited to Masaki Chiba, Kenichi Inaba, Arihiro Matsunaga, Hitoshi Sakamoto, Akira Shoujiguchi, Minoru Yoshikawa.
Application Number | 20140366572 14/370185 |
Document ID | / |
Family ID | 48745051 |
Filed Date | 2014-12-18 |
United States Patent
Application |
20140366572 |
Kind Code |
A1 |
Matsunaga; Arihiro ; et
al. |
December 18, 2014 |
COOLING DEVICE
Abstract
[Problem] When a size of a cooling device using a boiling
cooling system is reduced, a cooling performance decreases. [Means
for solving the problems] It is characterized in that an
evaporation unit which stores refrigerant, a condensing unit which
condenses a gas-phase refrigerant produced by vaporizing the
refrigerant in the evaporation unit to a liquid and dissipates
heat, a vapor pipe which conveys the gas-phase refrigerant to the
condensing unit, and a liquid pipe which conveys a liquid-phase
refrigerant obtained by condensing the gas-phase refrigerant in the
condensing unit to the evaporation unit are included, the
condensing unit includes a heat dissipation flow path, an upper
header which connects the vapor pipe and the heat dissipation flow
path, and a lower header which connects the heat dissipation flow
path and the liquid pipe, the upper header includes a flow path
header portion connected to the heat dissipation flow path and an
upper header extension portion located around the flow path header
portion, and the upper header extension portion has a connection
port connected to the vapor pipe in a face to which the heat
dissipation flow path is connected.
Inventors: |
Matsunaga; Arihiro; (Tokyo,
JP) ; Yoshikawa; Minoru; (Tokyo, JP) ;
Sakamoto; Hitoshi; (Tokyo, JP) ; Shoujiguchi;
Akira; (Tokyo, JP) ; Chiba; Masaki; (Tokyo,
JP) ; Inaba; Kenichi; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MATSUNAGA; Arihiro
YOSHIKAWA; Minoru
SAKAMOTO; Hitoshi
SHOUJIGUCHI; Akira
CHIBA; Masaki
INABA; Kenichi
NEC Corporation |
Minato-ku, Tokyo
Minato-ku, Tokyo
Minato-ku, Tokyo
Minato-ku, Tokyo
Minato-ku, Tokyo
Minato-ku, Tokyo
Minato-ku, Tokyo |
|
JP
JP
JP
JP
JP
JP
JP |
|
|
Family ID: |
48745051 |
Appl. No.: |
14/370185 |
Filed: |
December 12, 2012 |
PCT Filed: |
December 12, 2012 |
PCT NO: |
PCT/JP2012/007942 |
371 Date: |
July 1, 2014 |
Current U.S.
Class: |
62/513 |
Current CPC
Class: |
F25B 2339/02 20130101;
F25B 39/00 20130101; H01L 2924/0002 20130101; H01L 23/427 20130101;
F25B 39/04 20130101; F25B 23/006 20130101; H01L 2924/0002 20130101;
F25B 39/028 20130101; F28D 2021/0028 20130101; F28D 15/0266
20130101; F25B 2339/041 20130101; H01L 2924/00 20130101 |
Class at
Publication: |
62/513 |
International
Class: |
F25B 39/00 20060101
F25B039/00; F25B 39/04 20060101 F25B039/04; F25B 39/02 20060101
F25B039/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 4, 2012 |
JP |
2012-000038 |
Claims
1. A cooling device comprising: an evaporation unit which stores
refrigerant; a condensing unit which condenses a gas-phase
refrigerant produced by vaporizing the refrigerant in the
evaporation unit to a liquid and dissipates heat; a vapor pipe
which conveys the gas-phase refrigerant to the condensing unit; and
a liquid pipe which conveys a liquid-phase refrigerant obtained by
condensing the gas-phase refrigerant in the condensing unit to the
evaporation unit, wherein the condensing unit includes a heat
dissipation flow path, an upper header which connects the vapor
pipe and the heat dissipation flow path, and a lower header which
connects the heat dissipation flow path and the liquid pipe, the
upper header includes a flow path header portion connected to the
heat dissipation flow path and an upper header extension portion
located around the flow path header portion, and the upper header
extension portion has a connection port connected to the vapor pipe
in a face to which the heat dissipation flow path is connected.
2. The cooling device described in claim 1, wherein a width of the
upper header extension portion in a direction from the connection
port toward the flow path header and a width thereof in a vertical
direction are approximately equal to a width of the flow path
header portion in a direction from the connection port toward the
flow path header and a width thereof in a vertical direction,
respectively.
3. The cooling device described in claim 1, wherein a width of the
upper header extension portion in a direction from the connection
port toward the flow path header and a width thereof in the
vertical direction are smaller than a width of the flow path header
portion in a direction from the connection port toward the flow
path header and a width thereof in the vertical direction,
respectively.
4. The cooling device described in claim 1, wherein a
cross-sectional area of the upper header extension portion in the
direction from the connection port toward the flow path header and
a cross-sectional area thereof in the vertical direction are
greater than the cross-sectional area of the vapor pipe.
5. The cooling device described in claim 1, wherein a length of the
upper header extension portion in the direction from the connection
port toward the flow path header is smaller than the length of the
vapor pipe in the vertical direction.
6. The cooling device described in claim 1, wherein the cooling
device includes a plurality of the vapor pipes and the evaporation
unit is connected to the upper header by a plurality of the vapor
pipes.
7. The cooling device described in claim 1, wherein the condensing
unit is composed of a plurality of the heat dissipation flow paths
and the vapor pipe is disposed in a direction perpendicular to a
direction in which a plurality of the heat dissipation flow paths
are disposed in parallel.
8. The cooling device described in claim 1, wherein the condensing
unit is composed of a plurality of the heat dissipation flow paths
and the vapor pipe is disposed in line approximately parallel to
the direction in which a plurality of the heat dissipation flow
paths are disposed in parallel.
9. The cooling device described in claim 1, wherein the vapor pipe
is extended in a straight line shape in a vertical direction.
10. The cooling device described in claim 1, wherein the vapor pipe
connects an upper part of the evaporation unit and a lower surface
part of the upper header and the liquid pipe connects a side
surface part of the evaporation unit and the lower header.
11. The cooling device described in claim 1, wherein the cooling
device includes a plurality of the heat dissipation flow paths, a
heat dissipation fin is disposed in between a plurality of the
adjacent heat dissipation flow paths, and the heat dissipation fin
is thermally connected to the heat dissipation flow path.
12. The cooling device described in claim 1, wherein one of the
vapor pipe and the liquid pipe has a structure in which an inner
layer is a metal layer and an outer layer is a resin layer.
Description
TECHNICAL FIELD
[0001] The present invention relates to a cooling device and in
particular, relates to a cooling device using a phase change of a
refrigerant.
BACKGROUND ART
[0002] In recent years, in order to improve a processing speed of
an electronic equipment, a plurality of central processing units
(CPUs) are mounted on a circuit board.
[0003] The circuit board is installed in an electronic device with
a hard disk device or the like in high density.
[0004] Generally, when a temperature of a semiconductor device such
as a CPU or the like exceeds a predetermined temperature, not only
the performance of the semiconductor device cannot be maintained
but also the semiconductor device is destroyed in some cases. For
this reason, a temperature control using cooling or the like is
required and a technology by which the semiconductor device in
which the amount of heat generated increases can be efficiently
cooled is strongly desired.
[0005] Accordingly, a study of the boiling cooling system in which
the cooling is performed by using a phase change of a refrigerant
is performed. In the boiling cooling system, the refrigerant is
boiled by the heat generated by a heating element in an evaporation
unit and the vapor of the refrigerant is sent to a condensing unit.
Whereby, the heat is conveyed and the cooling is performed.
[0006] When described in detail, the vapor of the refrigerant that
is produced by vaporizing the refrigerant by the heat of the
heating element in the evaporation unit is circulated by using the
buoyancy due to the density difference between a gas and a liquid
and sent to the condensing unit. When the refrigerant is cooled by
the heat exchange with the outside air in the condensing unit, the
vapor of the refrigerant (gas-phase refrigerant) is condensed to a
liquid and the heat generated by the heating element is dissipated
to the outside. Further, the refrigerant obtained by condensing the
gas-phase refrigerant flows back to the evaporation unit by
gravity.
[0007] A cooling system mounted on an electronic circuit board is
described in patent document 1. The above-mentioned cooling system
includes a heat receiving jacket which vaporizes the liquid
refrigerant by the heat generated by a semiconductor device, a
condenser which condenses the refrigerant vapor to a liquid by
conducting the heat to the outside, a first pipe (a vapor pipe)
which conveys the refrigerant vapor to the condenser from the heat
receiving jacket, and a second pipe (a liquid return pipe) which
conveys the liquid refrigerant to the heat receiving jacket from
the condenser. Further, the condenser includes a pair of headers
and a plurality of flow paths having a flat shape between the pair
of headers. The vapor pipe and the liquid return pipe are
sandwiched between the pair of headers of the condenser and
connected to each other.
[0008] By using the above-mentioned structure, the refrigerant is
circulated in the cooling system by using the phase change in which
the refrigerant is vaporized by the heat of the semiconductor
device. The vapor of the refrigerant which is conveyed to an upper
part of the condenser extending in a vertical direction is
condensed to the liquid refrigerant by the heat exchange with the
outside. The liquid refrigerant flows to a lower part of the
condenser and flows back to the heat receiving jacket.
PRIOR ART DOCUMENT
Patent Document
[0009] [patent document 1] Japanese Patent Application Laid-Open
No. 2011-47616
BRIEF SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
[0010] With the increase of the amount of heat generation of the
semiconductor device such as a CPU or the like, as an alternative
of a heat sink, a request for mounting the cooling device using the
boiling cooling system in the electronic equipment such as a server
or the like increases. When the cooling device using the boiling
cooling system is mounted in the electronic equipment such as the
server or the like, with the decrease in size of the electronic
equipment, it is necessary to reduce the height of the cooling
device using the boiling cooling system and dispose the condensing
unit near a heat receiving unit.
[0011] However, in the cooling device described in patent document
1, because the vapor pipe is connected to a side surface part of
the header of the condenser, it is required that the thickness of
the header is greater than the outer diameter of the vapor pipe. In
other words, because the minimum thickness of the header is
limited, when the height of the cooling device is reduced, the
length of a flat pipe for dissipating heat has to be shortened.
Therefore, a problem in which a cooling performance decreases
occurs.
[0012] Further, when the evaporation unit and the condensing unit
are closely disposed to reduce the size of the cooling device, the
curvature of the vapor pipe becomes large and whereby it becomes
difficult to achieve a bending work. Therefore, a problem in which
a manufacturing accuracy is reduced and a cost increases occurs. On
the other hand, when the narrow vapor pipe is used, a problem in
which the internal pressure of the refrigerant increases and
whereby the cooling performance decreases occurs.
[0013] Thus, when the size of the cooling device described in
patent document 1 is reduced, a problem in which the cooling
performance decreases occurs.
[0014] An object of the present invention is to provide a cooling
device which can solve the above-mentioned problem in which the
cooling performance decreases when the size of the cooling device
is reduced.
Means for Solving the Problems
[0015] It is characterized in that an evaporation unit which stores
a refrigerant, a condensing unit which condenses a gas-phase
refrigerant produced by vaporizing the refrigerant in the
evaporation unit to a liquid and dissipates heat, a vapor pipe
which conveys the gas-phase refrigerant to the condensing unit, and
a liquid pipe which conveys a liquid-phase refrigerant obtained by
condensing the gas-phase refrigerant in the condensing unit to the
evaporation unit are included, the condensing unit includes a heat
dissipation flow path, an upper header which connects the vapor
pipe and the heat dissipation flow path, and a lower header which
connects the heat dissipation flow path and the liquid pipe, the
upper header includes a flow path header portion connected to the
heat dissipation flow path and an upper header extension portion
located around the flow path header portion, and the upper header
extension portion has a connection port for connecting to the vapor
pipe in a face to which the heat dissipation flow path is
connected.
Effect of the Invention
[0016] By the cooling device of the present invention, the cooling
device using the boiling cooling system which has a sufficient
cooling performance even when the size of the cooling device is
reduced can be obtained.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a perspective view showing a structure of a
cooling device according to a first exemplary embodiment of the
present invention.
[0018] FIG. 2 is a perspective view showing a structure of a
cooling device according to a second exemplary embodiment of the
present invention.
[0019] FIG. 3 is a schematic view for explaining action of a
cooling device according to a second exemplary embodiment of the
present invention.
[0020] FIG. 4 is a perspective view showing a structure of a
cooling device according to a third exemplary embodiment of the
present invention.
[0021] FIG. 5 is a perspective view showing a structure of a
cooling device according to a third exemplary embodiment of the
present invention.
[0022] FIG. 6 is a perspective view showing a structure of a
cooling device according to a fourth exemplary embodiment of the
present invention.
MODE FOR CARRYING OUT THE INVENTION
[0023] A preferred mode for carrying out the present invention will
be described below by using a drawing. In the exemplary embodiment
described below, a technically desirable limitation is included to
carry out the present invention. However, this does not limit the
scope of the invention.
First Exemplary Embodiment
[0024] First, this exemplary embodiment will be described in detail
with reference to the drawing. FIG. 1 is a perspective view showing
a structure of a cooling device 10 according to this exemplary
embodiment.
Explanation of the Structure
[0025] As shown in FIG. 1, the cooling device 10 according to this
exemplary embodiment includes an evaporation unit 1, a condensing
unit 2, a vapor pipe 3, and a liquid pipe 4.
[0026] The evaporation unit 1 has an enclosed structure and stores
a refrigerant therein. In the cooling device 10, the air is
exhausted by a pump or the like and an internal pressure is equal
to a saturated vapor pressure of the refrigerant. In this exemplary
embodiment, specifically, HFC (hydro fluorocarbon) or HFE (hydro
fluor ether) is used for the refrigerant. However, it is not
limited to these fluids. Further, the evaporation unit 1 is set so
that a lower surface part of the evaporation unit 1 is thermally
connected to the heating element and used. The refrigerant receives
heat generated by the heating element and boils.
[0027] The heating element is an element which generates heat when
it operates. For example, it is a CPU or the like. It is not
limited in particular. Further, although the heating element is not
shown in a figure, it may be mounted on a substrate. It is
desirable that the surface of the heating element which contacts
with the evaporation unit 1 is thermally connected to the
evaporation unit 1 through a resin having high thermal conductivity
or the like such as a heat conduction grease or the like.
[0028] The condensing unit 2 is composed of an upper header 5, a
lower header 6, and a heat dissipation flow path 7.
[0029] The heat dissipation flow path 7 has a shape extending in a
vertical direction. An upper end part of the heat dissipation flow
path 7 is connected to the upper header 5 and a lower end part
thereof is connected to the lower header 6.
[0030] The heat dissipation flow path 7 has a hollow tube shape and
the refrigerant flows in an internal space. Further, it is
desirable that the heat dissipation flow path 7 has a flat shape.
However, the shape is not limited to this shape. Further, a
material having high thermal conductivity such as copper, aluminum,
or the like can be used for the material of the heat dissipation
flow path 7. The material is not limited in particular.
[0031] The vapor pipe 3 connects an upper part of the evaporation
unit 1 and the upper header 5 and conveys the vapor of the
refrigerant (gas-phase refrigerant) that is produced by vaporizing
the refrigerant in the evaporation unit 1 to the heat dissipation
flow path 7 via the upper header 5.
[0032] The liquid pipe 4 connects the lower header 6 and a lower
part or a side surface part of the evaporation unit 1 and conveys
the liquefied refrigerant (liquid-phase refrigerant) obtained by
condensing the gas-phase refrigerant in the condensing unit 2 to
the evaporation unit 1.
[0033] Further, the vapor pipe 3 and the liquid pipe 4 may have a
bilayer structure in which an inner layer is a metal layer and an
outer layer is a resin layer or a single layer structure in which
an inner layer is a metal layer and an outer layer is a metal
layer.
[0034] The upper header 5 is composed of a flow path header portion
5a connected to the heat dissipation flow path 7 and an upper
header extension portion 5b located around the flow path header
portion 5a. The lower surface part of the flow path header portion
5a is connected to the heat dissipation flow path 7. Further, a
connection port 20 connected to the vapor pipe 3 is provided in the
lower surface part of the upper header extension portion 5b.
Namely, the lower surface part of the upper header 5 composed of
the flow path header portion 5a and the upper header extension
portion 5b is connected to the vapor pipe 3 and the heat
dissipation flow path 7.
[0035] In other words, the lower surface part of the upper header 5
connects the vapor pipe 3 and the heat dissipation flow path 7.
Whereby, the upper header 5 conveys the vapor of the refrigerant
(gas-phase refrigerant) that is conveyed by the vapor pipe 3 to the
heat dissipation flow path 7. Further, an area of the lower surface
part of the upper header 5 is determined so as to be greater than a
cross-sectional area perpendicular to the vertical direction of the
heat dissipation flow path 7 by at least an area of the upper
header extension portion 5b.
[0036] Further, the vapor pipe 3 connects the upper part of the
evaporation unit 1 and the lower surface part of the upper header
5. Therefore, as shown in FIG. 1, a pipe having a shape extending
in a straight line shape can be used for the vapor pipe 3.
Therefore, a bending work or the like is not required to produce
it.
[0037] In FIG. 1, an upper surface part of the lower header 6 is
connected to the heat dissipation flow path 7 and a side surface
part thereof is connected to the liquid pipe 4. However, the
connection relationship of the lower header 6 is not limited in
particular. When the vapor of the refrigerant flows in the heat
dissipation flow path 7, the vapor of the refrigerant is condensed
to the liquid. The lower header 6 collects the liquefied
refrigerant (liquid-phase refrigerant). The liquefied refrigerant
(liquid-phase refrigerant) flows back to the evaporation unit 1
through the liquid pipe 4.
Explanation of the Action and Effect
[0038] Next, the action and effect of this exemplary embodiment
will be described.
[0039] The evaporation unit 1 is made of a material having high
thermal conductivity and thermally connected to the heating element
through a heat conduction grease or the like. Therefore, the heat
generated by the heating element is conducted to the refrigerant
provided inside the evaporation unit 1 through the evaporation unit
1.
[0040] The refrigerant receives the heat generated by the heating
element and boils. The vapor of the refrigerant (gas-phase
refrigerant) that is generated when the refrigerant provided in a
closed space of the evaporation unit 1 boils flows to the upper
header 5 through the vapor pipe 3 by buoyancy due to the density
difference between the gas and the liquid.
[0041] The vapor of the refrigerant (gas-phase refrigerant) that is
conveyed to the upper header 5 flows the heat dissipation flow path
7 and whereby, the heat exchange with the outside air is performed.
When the heat dissipation flow path 7 is cooled, the vapor of the
refrigerant (gas-phase refrigerant) that flows inside the heat
dissipation flow path 7 is cooled and condensed to a liquid. The
liquefied refrigerant (liquid-phase refrigerant) falls to the lower
part of the heat dissipation flow path 7 by the gravity and flows
back to the evaporation unit 1 through the liquid pipe 4. The
refrigerant boils by the heat generated by the heating element in
the evaporation unit 1 again and a cooling cycle is repeated.
[0042] Thus, the refrigerant provided inside the evaporation unit 1
changes from the liquid to the gas by the heat generated by the
heating element and when it flows in the heat dissipation flow path
7, it is cooled and the gas is condensed to the liquid again.
Namely, the phase of the refrigerant is repeatedly changed from the
liquid phase to the gas phase and from the gas phase to the liquid
phase and whereby, the heat generated by the heating element is
dissipated through the heat dissipation flow path 7.
[0043] When an amount of heat generation that is generated by the
heating element is large, in order to cool the heating element,
much refrigerant is required. However, when the liquid vaporizes,
its volume increases by more than several hundred times. Therefore,
when the refrigerant boils and vaporizes by the heat generated by
the heating element, the internal pressure of the evaporation unit
1 and the vapor pipe 3 in which the vapor of the refrigerant
(gas-phase refrigerant) flows increases.
[0044] When the internal pressure of the evaporation unit 1
increases, not only the evaporation unit 1 deforms but also a
problem in which a cooling performance decreases occurs because the
boiling point of the refrigerant increases. Accordingly, in this
exemplary embodiment, the cross-sectional area of the vapor pipe 3
is made greater than that of the liquid pipe 4 and the volume of
the evaporation unit 1 and the volume of the vapor pipe 3 are
increased. Whereby, the internal pressure increase is avoided.
[0045] However, in the structure described in patent document 1,
the side surface part of the upper header is connected to the vapor
pipe. Therefore, the thickness of the upper header has to be at
least greater than the outer diameter of the vapor pipe. As a
result, when the height of the cooling device is reduced, because
the thickness of the upper header cannot be reduced, the length of
the flat pipe has to be shortened. Accordingly, a problem in which
the cooling performance decreases occurs.
[0046] In contrast, the upper header 5 of the cooling device 10
according to this exemplary embodiment is connected to the vapor
pipe 3 at the connection port 20 disposed in the lower surface part
of an extension header unit 5b. In other words, because the side
surface part of the upper header 5 is not connected to the vapor
pipe 3, the thickness in the vertical direction can be reduced.
[0047] In the cooling device 10, it is not necessary to increase
the thickness of the upper header 5 in order to avoid the decrease
in cooling performance due to rapid increase of the volume of the
refrigerant when the phase of the refrigerant is changed from the
liquid phase to the gas phase. As a result, the height of the
cooling device 10 can be reduced. Namely, by the cooling device 10
according to this exemplary embodiment, the cooling device 10 using
the boiling cooling system which has a sufficient cooling
performance even when the size of the cooling device 10 is reduced
can be obtained.
[0048] In other words, when the mounting height of the cooling
device 10 is limited, by reducing the thickness of the upper header
5, the length of the heat dissipation flow path 7 can be made long.
Therefore, the cooling performance can be further improved.
[0049] Further, a pipe having a straight line shape can be used for
the vapor pipe 3 which connects the upper part of the evaporation
unit 1 and the lower surface part of the upper header 5. Therefore,
it is not necessary to deform the vapor pipe 3 having a large
cross-sectional area and the cost for the manufacturing process can
be reduced.
[0050] Further, because a bending work is not required to produce
the vapor pipe 3, the condensing unit 2 can be disposed near the
evaporation unit 1 and the size of the cooling device 10 can be
further reduced.
[0051] When the vapor pipe 3 and the liquid pipe 4 have a bilayer
structure in which an inner layer is a metal layer and an outer
layer is a resin layer, the following effect is obtained. Namely,
even when the vapor of the refrigerant (gas-phase refrigerant) or
the high temperature refrigerant flows inside the vapor pipe 3 and
the liquid pipe 4, because the inner layer is a resin layer,
generation of uncondensed gas due to reaction between the
refrigerant and the resin layer can be prevented. As a result, the
decrease in cooling performance due to the increase of the internal
pressure inside a cooler caused by the generation of the
uncondensed gas can be prevented.
Second Exemplary Embodiment
[0052] Next, a second exemplary embodiment will be described in
detail with reference to FIG. 2. FIG. 2 is a perspective view of
the cooling device 10 according to this exemplary embodiment.
Explanation of the Structure
[0053] The cooling device 10 according to this exemplary embodiment
has a structure in which the cross-sectional area of the upper
header extension portion 5b is greater than the cross-sectional
area of the vapor pipe 3. The cross-sectional area of the upper
header extension portion 5b is a cross-sectional area perpendicular
to a direction from the connection port 20 connected to the vapor
pipe 3 toward the flow path header 5a. This is a difference between
the cooling device 10 according to the second exemplary embodiment
and the cooling device 10 according to the first exemplary
embodiment. Besides the above-mentioned difference, the structure
and the connection relationship of the cooling device 10 according
to the second exemplary embodiment are the same as those of the
cooling device 10 according to the first exemplary embodiment and
the cooling device 10 according to the second exemplary embodiment
includes the evaporation unit 1, the condensing unit 2, the vapor
pipe 3, and the liquid pipe 4.
[0054] The evaporation unit 1 has an enclosed structure and stores
the refrigerant therein. In the cooling device 10, the internal
pressure is kept equal to a saturated vapor pressure in a state in
which the inside thereof is decompressed by a pump or the like.
Further, the lower surface part of the evaporation unit 1 is
thermally connected to the heating element when the evaporation
unit 1 is used. Therefore, the refrigerant receives the heat
generated by the heating element and boils.
[0055] The heat dissipation flow path 7 has a shape extending in
the vertical direction. The upper end part of the heat dissipation
flow path 7 is connected to the upper header 5 and the lower end
part thereof is connected to the lower header 6. The vapor pipe 3
connects the upper part of the evaporation unit 1 and the upper
header 5 and conveys the vapor of the refrigerant (gas-phase
refrigerant) that is produced by vaporizing the refrigerant in the
evaporation unit 1 to the heat dissipation flow path 7 via the
upper header. The liquid pipe 4 connects the lower header 6 and the
lower part of the evaporation unit 1 and conveys the liquefied
refrigerant (liquid-phase refrigerant) obtained by condensing the
gas-phase refrigerant in the condensing unit 2 to the evaporation
unit 1.
[0056] The upper header 5 is composed of the flow path header
portion 5a connected to the heat dissipation flow path 7 and the
upper header extension portion 5b located around the flow path
header portion 5a. The lower surface part of the flow path header
portion 5a is connected to the heat dissipation flow path 7.
Further, the connection port 20 connected to the vapor pipe 3 is
provided in the lower surface part of the upper header extension
portion 5b. Namely, the lower surface part of the upper header 5
composed of the flow path header portion 5a and the upper header
extension portion 5b is connected to the vapor pipe 3 and the heat
dissipation flow path 7. The upper header 5 conveys the vapor of
the refrigerant (gas-phase refrigerant) that is conveyed by the
vapor pipe 3 to the heat dissipation flow path 7.
[0057] As shown in FIG. 2, the cooling device 10 according to this
exemplary embodiment has a structure in which a cross-sectional
area perpendicular to a direction from the connection port 20 of
the upper header extension portion 5b toward the flow path header
5a is greater than the cross-sectional area perpendicular to a
vertical direction of the vapor pipe 3. Further, the arrangement of
the vapor pipe 3 is not limited in particular.
Explanation of the Action and Effect
[0058] Next, the action and effect of this exemplary embodiment
will be described.
[0059] The refrigerant provided in the evaporation unit 1 receives
the heat generated by the heating element and boils. The vapor of
the refrigerant that is generated when the refrigerant boils is
conveyed to the upper header 5 through the vapor pipe 3 by buoyancy
due to the density difference between the gas and the liquid.
[0060] The vapor of the refrigerant (gas-phase refrigerant) that is
conveyed to the upper header 5 flows in the heat dissipation flow
path 7 and whereby, the heat exchange with the outside air is
performed. When the heat dissipation flow path 7 is cooled, the
vapor of the refrigerant (gas-phase refrigerant) that flows inside
the heat dissipation flow path 7 is cooled and condensed to the
liquid. The liquefied refrigerant (liquid-phase refrigerant) falls
to the lower part of the heat dissipation flow path 7 by the
gravity and flows back to the evaporation unit 1. The refrigerant
boils by the heat generated by the heating element in the
evaporation unit 1 again and the cooling cycle is repeated.
[0061] In other words, the refrigerant provided inside the
evaporation unit 1 changes from the liquid to the gas by the heat
generated by the heating element and when it flows in the heat
dissipation flow path 7, it is cooled and the gas is condensed to
the liquid again. Namely, the phase of the refrigerant is
repeatedly changed from the liquid phase to the gas phase and from
the gas phase to the liquid phase and whereby, the heat generated
by the heating element is dissipated through the heat dissipation
flow path 7.
[0062] The cross-sectional area perpendicular to a direction from
the connection port 20 of the upper header extension portion 5b
according to this exemplary embodiment toward the flow path header
5a is greater than the cross-sectional area perpendicular to a
vertical direction of the vapor pipe 3. By using the
above-mentioned structure, the cooling device 10 can reduce a
pressure loss of the vapor of the refrigerant (gas-phase
refrigerant) and improve the cooling performance in the evaporation
unit 1.
[0063] Explanation will be made in detail by using FIG. 3. The
vapor of the refrigerant (gas-phase refrigerant) generated when the
refrigerant boils by the heat of the heating element in the
evaporation unit 1 flows in a vertical upper direction through the
vapor pipe 3. The vapor pipe 3 is connected to the lower surface
part of the upper header extension portion 5b. Therefore, a flow
direction of the vapor of the refrigerant (gas-phase refrigerant)
changes from the vertical upper direction to a horizontal direction
at a connection point between the vapor pipe 3 and the upper header
extension portion 5b.
[0064] Here, it is assumed that the cross-sectional area
perpendicular to a direction from the connection port 20 of the
upper header extension portion 5b toward the flow path header 5a is
equal to or smaller than the cross-sectional area perpendicular to
a vertical direction of the vapor pipe 3. In this case, it is
estimated that the vapor of the refrigerant (gas-phase refrigerant)
flows in the upper header extension portion 5b at a speed that is
equal to or faster than a speed at which it flows in the vertical
upper direction in the vapor pipe 3.
[0065] However, the flow direction of the vapor of the refrigerant
(gas-phase refrigerant) is changed from the vertical upper
direction to the horizontal direction at the connection point
between the vapor pipe 3 and the upper header extension portion 5b.
Therefore, when the flow direction of the vapor of the refrigerant
(gas-phase refrigerant) is changed while keeping the speed of flow
constant, a pressure loss occurs at the connection point between
the vapor pipe 3 and the upper header extension portion 5b and the
cooling performance decreases.
[0066] In contrast, the cooling device 10 according to this
exemplary embodiment has a structure in which the cross-sectional
area perpendicular to a direction from the connection port 20 of
the upper header extension portion 5b toward the flow path header
5a is greater than the cross-sectional area perpendicular to a
vertical direction of the vapor pipe 3.
[0067] Because the cooling device 10 according to this exemplary
embodiment has the above-mentioned structure, the speed of flow of
the vapor of the refrigerant (gas-phase refrigerant) that flows in
the upper header extension portion 5b decreases. Therefore, the
pressure loss that occurs when the flow direction of the vapor of
the refrigerant (gas-phase refrigerant) is changed from the
vertical upper direction in which the vapor of the refrigerant
flows in the vapor pipe 3 to the horizontal direction in which it
flows in the upper header extension portion 5b at a connection
point between the vapor pipe 3 and the upper header extension
portion 5b can be reduced. As a result, the cooling performance of
the cooling device 10 can be further improved.
[0068] Namely, when the flow direction of the vapor of the
refrigerant (gas-phase refrigerant) is changed from the vertical
upper direction to the horizontal direction at the connection point
between the vapor pipe 3 and the upper header extension portion 5b,
the flow speed is reduced. Therefore, occurrence of the pressure
loss can be prevented.
[0069] When the width of the upper header extension portion 5b in
the direction from the connection port 20 toward the flow path
header 5a and the width thereof in the vertical direction are at
least greater than the outer diameter of the vapor pipe 3, the
widths of the upper header extension portion 5b in those directions
may be smaller than the widths of the flow path header portion in
those directions, respectively.
[0070] Further, the width of the upper header extension portion 5b
in the direction from the connection port 20 toward the flow path
header 5a and the width of the upper header extension portion 5b in
the vertical direction are approximately equal to the widths of the
flow path header portion 5a in those directions, respectively, the
upper header extension portion 5b and the flow path header portion
5a can be manufactured in the same process. Therefore, the
manufacturing cost can be suppressed.
[0071] It is desirable that the length of the upper header
extension portion 5b in the direction from the connection port 20
toward the flow path header 5a is smaller than the length of the
vapor pipe 3 in the vertical direction.
[0072] In the vapor pipe 3 extending in the vertical direction, the
refrigerant vapor (gas-phase refrigerant) receives a buoyancy force
continuously. On the other hand, in the upper header extension
portion 5b, the refrigerant vapor moves in the horizontal
direction. Therefore, it does not receive the buoyancy force and
loses the energy by friction with the wall continuously.
[0073] Therefore, when the length of the upper header extension
portion 5b in the direction from the connection port 20 toward the
flow path header 5a is smaller than the length of the vapor pipe 3
in the vertical direction, the influence on the cooling performance
is small.
Third Exemplary Embodiment
[0074] Next, a third exemplary embodiment will be described in
detail by using FIGS. 4 and 5. FIGS. 4 and 5 are perspective views
showing a structure of the cooling device 10 according to this
exemplary embodiment.
Explanation of the Structure
[0075] The condensing unit 2 of the cooling device 10 according to
this exemplary embodiment is composed of a plurality of the heat
dissipation flow paths 7 and the vapor pipe 3 is disposed in a
direction perpendicular to the direction in which a plurality of
the heat dissipation flow paths 7 are disposed in parallel. This is
a difference between the cooling device 10 according to the third
exemplary embodiment and the cooling device 10 according to the
first exemplary embodiment. Besides the above-mentioned difference,
the structure and the connection relationship of the cooling device
10 according to the third exemplary embodiment are the same as
those of the cooling device 10 according to the first exemplary
embodiment and the cooling device 10 according to the third
exemplary embodiment includes the evaporation unit 1, the
condensing unit 2, the vapor pipe 3, and the liquid pipe 4.
[0076] The evaporation unit 1 has an enclosed structure and stores
the refrigerant therein. In the cooling device 10, the air is
exhausted by a pump or the like and the internal pressure is equal
to the saturated vapor pressure of the refrigerant. Further, the
evaporation unit 1 is set so that the lower surface part of the
evaporation unit 1 is thermally connected to the heating element
and used. The refrigerant receives the heat generated by the
heating element and boils.
[0077] The condensing unit 2 according to this exemplary embodiment
is composed of a plurality of the heat dissipation flow paths 7 and
a heat dissipation fin 8 is provided in between a plurality of the
heat dissipation flow paths 7. The heat dissipation fin 8 is
disposed in between the adjacent heat dissipation flow paths 7 and
thermally connected to the adjacent heat dissipation flow paths
7.
[0078] Further, the heat dissipation flow path 7 has a shape
extending in the vertical direction. The upper end part of the heat
dissipation flow path 7 is connected to the upper header 5 and the
lower end part thereof is connected to the lower header 6. The
vapor pipe 3 connects the upper part of the evaporation unit 1 and
the upper header 5 and conveys the vapor of the refrigerant
(gas-phase refrigerant) that is produced by vaporizing the
refrigerant in the evaporation unit 1 to the heat dissipation flow
path 7 via the upper header 5. The liquid pipe 4 connects the lower
header 6 and the lower part of the evaporation unit 1 and conveys
the liquefied refrigerant (liquid-phase refrigerant) obtained by
condensing the gas-phase refrigerant in the condensing unit 2 to
the evaporation unit 1.
[0079] The upper header 5 is composed of the flow path header
portion 5a connected to the heat dissipation flow path 7 and the
upper header extension portion 5b located around the flow path
header portion 5a. The lower surface part of the flow path header
portion 5a is connected to the heat dissipation flow path 7.
Further, the connection port 20 connected to the vapor pipe 3 is
provided in the lower surface part of the upper header extension
portion 5b. Namely, the lower surface part of the upper header 5
composed of the flow path header portion 5a and the upper header
extension portion 5b is connected to the vapor pipe 3 and the heat
dissipation flow path 7. The upper header 5 conveys the vapor of
the refrigerant (gas-phase refrigerant) that is conveyed through
the vapor pipe 3 to the heat dissipation flow path 7.
[0080] In the condensing unit 2 according to this exemplary
embodiment, a plurality of the heat dissipation flow paths 7 are
provided. As shown in FIG. 4, a plurality of the heat dissipation
flow paths 7 are disposed in parallel and connected to the flow
path header 5a.
[0081] The vapor pipe 3 is disposed in a direction perpendicular to
the direction in which a plurality of the heat dissipation flow
paths 7 are disposed in parallel. In other words, the vapor pipe 3
is disposed at a position facing the condensing unit 2. When a
plurality of heating elements exist or when a large amount of heat
is generated by the heating element, as shown in FIG. 5, a
plurality of the evaporation units 1 may be connected to the upper
header extension portion 5b by using a plurality of the vapor pipes
3.
Explanation of the Action and Effect
[0082] Next, the action and effect of this exemplary embodiment
will be described.
[0083] The refrigerant provided in the evaporation unit 1 receives
the heat generated by the heating element and boils. The vapor of
the refrigerant (gas-phase refrigerant) that is generated when the
refrigerant boils is conveyed to the upper header 5 through the
vapor pipe 3 by buoyancy due to the density difference between the
gas and the liquid.
[0084] The vapor of the refrigerant (gas-phase refrigerant) that is
conveyed to the upper header 5 flows in the heat dissipation flow
path 7 and whereby, the heat exchange with the outside air is
performed. When the heat dissipation flow path 7 is cooled, the
vapor of the refrigerant (gas-phase refrigerant) that flows inside
the heat dissipation flow path 7 is cooled and condensed to the
liquid. The liquefied refrigerant (liquid-phase refrigerant) falls
to the lower part of the heat dissipation flow path 7 by the
gravity and flows back to the evaporation unit 1. The refrigerant
boils by the heat generated by the heating element in the
evaporation unit 1 again and the cooling cycle is repeated.
[0085] In other words, the refrigerant provided inside the
evaporation unit 1 changes from the liquid to the gas by the heat
generated by the heating element and when it flows in the heat
dissipation flow path 7, it is cooled and the gas is condensed to
the liquid again. Namely, the phase of the refrigerant is
repeatedly changed from the liquid phase to the gas phase and from
the gas phase to the liquid phase and whereby, the heat generated
by the heating element is dissipated through the heat dissipation
flow path 7.
[0086] The condensing unit 2 according to this exemplary embodiment
includes a plurality of the heat dissipation flow paths 7. The heat
dissipation fin 8 is disposed in between a plurality of the
adjacent heat dissipation flow paths 7. By providing the heat
dissipation fin 8, a surface area of the heat dissipation flow path
7 is increased. Therefore, the cooling performance of the
refrigerant can be improved because the heat exchange with outside
air is promoted.
[0087] Further, when a plurality of the heat dissipation flow paths
7 are disposed in parallel, an area required to mount the cooling
device 10 is at least equal to an area corresponding to a sum of
the widths of a plurality of the heat dissipation flow paths 7. The
vapor pipe 3 according to this exemplary embodiment is disposed in
a direction perpendicular to the direction in which a plurality of
the heat dissipation flow paths 7 are disposed in parallel.
[0088] By using the above-mentioned structure, even when the vapor
pipe 3 is disposed, it is not necessary to further increase the
width of the face facing the vapor pipe 3 of the cooling device 10.
Therefore, the size of the cooling device 10 can be reduced.
Further, as shown in FIG. 5, by disposing a plurality of the vapor
pipes 3 in a direction perpendicular to the direction in which a
plurality of the heat dissipation flow paths 7 are disposed in
parallel, the cooling performance can be improved without
increasing the width of the area required to mount the cooling
device 10.
[0089] Further, as shown in FIG. 2, in a structure in which the
vapor pipe 3 is disposed in a direction perpendicular to the
direction in which a plurality of the heat dissipation flow paths 7
are disposed in parallel, the upper header extension portion 5b may
have a shape in which the upper header extension portion 5b is
extended in the direction toward the vapor pipe 3 so as to form a
roof that overhangs the vapor pipe 3.
[0090] By using the above-mentioned structure like the second
exemplary embodiment, a structure in which the cross-sectional area
perpendicular to the direction from the connection port 20 of the
upper header extension portion 5b toward the flow path header 5a is
greater than the cross-sectional area perpendicular to the vertical
direction of the vapor pipe 3 is used. Whereby, the pressure loss
of the vapor of the refrigerant (gas-phase refrigerant) can be
reduced and the cooling performance in the evaporation unit 1 can
be improved.
[0091] The cooling device 10 according to this exemplary embodiment
can have not only the above-mentioned action and effect but also a
duct effect. When described in detail, the upper header extension
portion 5b is extended in the direction toward the vapor pipe 3 so
as to form an overhanging roof. Whereby, the upper header extension
portion 5b can prevent the wind for cooling the heat dissipation
flow path 7 from flowing upward and control the flow direction of
the wind. As a result, the heat dissipation flow path 7 can be
cooled by the cooling wind flowing in the vertical direction.
Therefore, the pressure loss of the cooling wind can be reduced and
the efficient cooling can be realized.
Fourth Exemplary Embodiment
[0092] Next, a fourth exemplary embodiment will be described in
detail with reference to FIG. 6. FIG. 6 is a perspective view of
the cooling device 10 according to this exemplary embodiment.
Explanation of the Structure
[0093] The condensing unit 2 of the cooling device 10 according to
this exemplary embodiment has a structure in which a plurality of
the heat dissipation flow paths 7 are disposed in parallel. The
vapor pipe 3 is disposed in line approximately parallel to the
direction in which a plurality of the heat dissipation flow paths 7
are disposed in parallel. This is a difference between the cooling
device 10 according to the fourth exemplary embodiment and the
cooling device 10 according to the first exemplary embodiment.
Besides the above-mentioned difference, the structure and the
connection relationship of the cooling device 10 according to the
fourth exemplary embodiment are the same as those of the cooling
device 10 according to the first exemplary embodiment and the
cooling device 10 according to the fourth exemplary embodiment
includes the evaporation unit 1, the condensing unit 2, the vapor
pipe 3, and the liquid pipe 4.
[0094] The evaporation unit 1 has an enclosed structure and stores
the refrigerant therein. In the cooling device 10, the air is
exhausted by a pump or the like and the internal pressure is equal
to the saturated vapor pressure of the refrigerant. Further, the
evaporation unit 1 is set so that the lower surface part of the
evaporation unit 1 is thermally connected to the heating element
and used. The refrigerant receives heat generated by the heating
element and boils.
[0095] The condensing unit 2 according to this exemplary embodiment
is composed of a plurality of the heat dissipation flow paths 7 and
the heat dissipation fin 8 is provided in between a plurality of
the heat dissipation flow paths 7. The heat dissipation fin 8 is
disposed in between the adjacent heat dissipation flow paths 7 and
thermally connected to the adjacent heat dissipation flow paths
7.
[0096] Further, the heat dissipation flow path 7 has a shape
extending in the vertical direction. The upper end part of the heat
dissipation flow path 7 is connected to the upper header 5 and the
lower end part thereof is connected to the lower header 6. The
vapor pipe 3 connects the upper part of the evaporation unit 1 and
the upper header 5 and conveys the vapor of the refrigerant
(gas-phase refrigerant) that is produced by vaporizing the
refrigerant in the evaporation unit 1 to the heat dissipation flow
path 7 via the upper header 5. The liquid pipe 4 connects the lower
header 6 and the lower part of the evaporation unit 1 and conveys
the liquefied refrigerant (liquid-phase refrigerant) obtained by
condensing the gas-phase refrigerant in the condensing unit 2 to
the evaporation unit 1.
[0097] The upper header 5 is composed of the flow path header
portion 5a connected to the heat dissipation flow path 7 and the
upper header extension portion 5b located around the flow path
header portion 5a. The lower surface part of the flow path header
portion 5a is connected to the heat dissipation flow path 7.
Further, the connection port 20 connected to the vapor pipe 3 is
provided in the lower surface part of the upper header extension
portion 5b. Namely, the lower surface part of the upper header 5
composed of the flow path header portion 5a and the upper header
extension portion 5b is connected to the vapor pipe 3 and the heat
dissipation flow path 7. The upper header 5 conveys the vapor of
the refrigerant (gas-phase refrigerant) that is conveyed through
the vapor pipe 3 to the heat dissipation flow path 7.
[0098] As shown in FIG. 6, in the cooling device 10 according to
this exemplary embodiment, a plurality of the heat dissipation flow
paths 7 provided in the condensing unit 2 are disposed in parallel.
The vapor pipe 3 is disposed in line approximately parallel to the
direction in which a plurality of the heat dissipation flow paths 7
are disposed in parallel and connected to the upper header
extension portion 5b. In other words, the vapor pipe 3 is disposed
on an extension line in a direction in which a plurality of the
heat dissipation flow paths 7 are disposed in parallel.
Explanation of the Action and Effect
[0099] Next, the action and effect of this exemplary embodiment
will be described.
[0100] The refrigerant provided in the evaporation unit 1 receives
the heat generated by the heating element and boils. The vapor of
the refrigerant (gas-phase refrigerant) that is generated when the
refrigerant boils is conveyed to the upper header 5 through the
vapor pipe 3 by buoyancy due to the density difference between the
gas and the liquid.
[0101] The vapor of the refrigerant (gas-phase refrigerant) that is
conveyed to the upper header 5 flows in the heat dissipation flow
path 7 and whereby, the heat exchange with the outside air is
performed. When the heat dissipation flow path 7 is cooled, the
vapor of the refrigerant (gas-phase refrigerant) that flows inside
the heat dissipation flow path 7 is cooled and condensed to the
liquid. The liquefied refrigerant (liquid-phase refrigerant) falls
to the lower part of the heat dissipation flow path 7 by the
gravity and flows back to the evaporation unit 1. The refrigerant
boils by the heat generated by the heating element in the
evaporation unit 1 again and the cooling cycle is repeated.
[0102] In other words, the refrigerant provided inside the
evaporation unit 1 changes from the liquid to the gas by the heat
generated by the heating element and when it flows in the heat
dissipation flow path 7, it is cooled and the gas is condensed to
the liquid again. Namely, the phase of the refrigerant is
repeatedly changed from the liquid phase to the gas phase and from
the gas phase to the liquid phase and whereby, the heat generated
by the heating element is dissipated through the heat dissipation
flow path 7.
[0103] The condensing unit 2 according to this exemplary embodiment
includes a plurality of the heat dissipation flow paths 7. The heat
dissipation fin 8 is disposed in between a plurality of the
adjacent heat dissipation flow paths 7. By providing the heat
dissipation fin 8, a surface area of the heat dissipation flow path
7 is increased. Therefore, the cooling performance of the
refrigerant can be improved because the heat exchange with outside
air is promoted.
[0104] As shown in FIG. 6, the vapor pipe 3 according to this
exemplary embodiment is disposed in line approximately parallel to
the direction in which a plurality of the heat dissipation flow
paths 7 provided in the condensing unit 2 are disposed in parallel.
In other words, the vapor pipe 3 is disposed on an extension line
in a direction in which a plurality of the heat dissipation flow
paths 7 are disposed in parallel.
[0105] Therefore, because the flow of the cooling wind flowing in
the direction perpendicular to the direction in which a plurality
of the heat dissipation flow paths 7 are disposed in parallel is
not disturbed by the vapor pipe 3, the heat dissipation flow path 7
can be cooled efficiently. As a result, the cooling efficiency of
the cooling device 10 can be further improved.
[0106] This application claims priority from Japanese Patent
Application No. 2012-000038 filed on Jan. 4, 2012, the disclosure
of which is hereby incorporated by reference in its entirety.
[0107] The invention of the present application has been described
above with reference to the exemplary embodiment. However, the
invention of the present application is not limited to the above
mentioned exemplary embodiment. Various changes in the
configuration or details of the invention of the present
application that can be understood by those skilled in the art can
be made without departing from the scope of the invention of the
present application.
DESCRIPTION OF SYMBOL
[0108] 1 evaporation unit [0109] 2 condensing unit [0110] 3 vapor
pipe [0111] 4 liquid pipe [0112] 5 upper header [0113] 5a flow path
header portion [0114] 5b upper header extension portion [0115] 6
lower header [0116] 7 heat dissipation flow path [0117] 8 heat
dissipation fin [0118] 10 cooling device [0119] 20 connection
port
* * * * *