U.S. patent application number 13/533043 was filed with the patent office on 2013-01-24 for cooling unit.
This patent application is currently assigned to FUJITSU LIMITED. The applicant listed for this patent is Michimasa AOKI, Kenji KATSUMATA, Shinichirou KOUNO, Masaru SUGIE, Masumi SUZUKI, Yosuke TSUNODA. Invention is credited to Michimasa AOKI, Kenji KATSUMATA, Shinichirou KOUNO, Masaru SUGIE, Masumi SUZUKI, Yosuke TSUNODA.
Application Number | 20130020058 13/533043 |
Document ID | / |
Family ID | 47554965 |
Filed Date | 2013-01-24 |
United States Patent
Application |
20130020058 |
Kind Code |
A1 |
SUZUKI; Masumi ; et
al. |
January 24, 2013 |
COOLING UNIT
Abstract
A cooling unit includes: at least one pump that circulates
coolant; a tank having a first inlet through which coolant is
caused to flow in and at least one first outlet through which the
coolant is expelled to the at least one pump; and an air bubble
accumulating portion provided in an upper part of the tank, wherein
the first inlet is disposed at a position such that the coolant is
caused to flow into the air bubble accumulating portion, and the at
least one first outlet is provided below the air bubble
accumulating portion.
Inventors: |
SUZUKI; Masumi; (Kawasaki,
JP) ; AOKI; Michimasa; (Kawasaki, JP) ;
TSUNODA; Yosuke; (Tachikawa, JP) ; SUGIE; Masaru;
(Hino, JP) ; KOUNO; Shinichirou; (Machida, JP)
; KATSUMATA; Kenji; (Odawara, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SUZUKI; Masumi
AOKI; Michimasa
TSUNODA; Yosuke
SUGIE; Masaru
KOUNO; Shinichirou
KATSUMATA; Kenji |
Kawasaki
Kawasaki
Tachikawa
Hino
Machida
Odawara |
|
JP
JP
JP
JP
JP
JP |
|
|
Assignee: |
FUJITSU LIMITED
Kawasaki-shi
JP
|
Family ID: |
47554965 |
Appl. No.: |
13/533043 |
Filed: |
June 26, 2012 |
Current U.S.
Class: |
165/104.31 |
Current CPC
Class: |
G06F 1/20 20130101; G06F
2200/201 20130101; H05K 7/20772 20130101 |
Class at
Publication: |
165/104.31 |
International
Class: |
F28D 15/00 20060101
F28D015/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 22, 2011 |
JP |
2011-161356 |
Claims
1. A cooling unit comprising: at least one pump that circulates
coolant; a tank having a first inlet through which coolant is
caused to flow in and at least one first outlet through which the
coolant is expelled to the at least one pump; and an air bubble
accumulating portion provided in an upper part of the tank, wherein
the first inlet is disposed at a position such that the coolant is
caused to flow into the air bubble accumulating portion, and the at
least one first outlet is provided below the air bubble
accumulating portion.
2. The cooling unit according to claim 1, wherein the at least one
pump comprises a plurality of pumps, the at least one first outlet
comprises a plurality of first outlets, and the tank further has at
least one mixing chamber having a plurality of second inlets
connected to outlets of the plurality of pumps.
3. The cooling unit according to claim 2, wherein the at least one
mixing chamber has a second outlet through which the coolant
flowing in through the plurality of second inlets is expelled, and
a circulation loop that leads from the second outlet to the first
inlet and circulates the coolant is connected to the at least one
mixing chamber.
4. The cooling unit according to claim 3, wherein a radiating fin
that cools the coolant, and a cooling member that absorbs heat from
a heat-generating component with the coolant are connected to the
route of the circulation loop.
5. The cooling unit according to claim 2, wherein the at least one
mixing chamber comprises a plurality of mixing chambers, and the
tank further has a second mixing chamber in which the coolant from
the plurality of mixing chambers is mixed.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is based upon and claims the benefit of
priority of the prior Japanese Patent Application No. 2011-161356,
filed on Jul. 22, 2011, the entire contents of which are
incorporated herein by reference.
FIELD
[0002] The embodiments disclosed herein are related to a cooling
unit that cools electronic components mounted in an electronic
device, using coolant.
BACKGROUND
[0003] In recent years, in PC servers, the rack-mount system has
become mainstream. In the rack-mount system, a plurality of server
modules are mounted so that they are stacked on top of each other
in a rack cabinet. One or more integrated circuit elements (LSIs)
typified by processors (CPUs) are mounted on each server module. In
a server or a personal computer, a dedicated fan is placed
immediately above a component that generates a large amount of
heat, such as a CPU or an LSI, and the component is air-cooled so
as to stabilize the operation. However, in the rack mount system,
in order to improve performance and to save space, as many server
modules as possible have to be stacked in a rack cabinet. For this
reason, the thickness of individual server modules has to be
reduced. Thus, in rack-mounted server modules, it is difficult to
attach a fan directly to a component that generates a large amount
of heat, such as a CPU or an LSI. In addition, since the server
modules are stacked, it is difficult to release the heat generated
in individual server modules to the outside. In order to solve
these problems, there is a method to cool a CPU, an LSI, or the
like, including circulating coolant over a heat-generating
component, such as a CPU or an LSI, circulating the coolant that
has absorbed heat from the CPU, LSI, or the like to a radiator with
a pump, and cooling the coolant with a cooling fan
[0004] The following is reference documents:
[Document 1] Japanese Laid-open Patent Publication No.
2004-319628
[Document 2] Japanese Laid-open Patent Publication No.
2005-26498
SUMMARY
[0005] According to an aspect of the invention, a cooling unit
includes: at least one pump that circulates coolant; a tank having
a first inlet through which coolant is caused to flow in and at
least one first outlet through which the coolant is expelled to the
at least one pump; and an air bubble accumulating portion provided
in an upper part of the tank, wherein the first inlet is disposed
at a position such that the coolant is caused to flow into the air
bubble accumulating portion, and the at least one first outlet is
provided below the air bubble accumulating portion.
[0006] The object and advantages of the invention will be realized
and attained by means of the elements and combinations particularly
pointed out in the claims.
[0007] It is to be understood that both the foregoing general
description and the following detailed description are exemplary
and explanatory and are not restrictive of the invention, as
claimed.
BRIEF DESCRIPTION OF DRAWINGS
[0008] FIG. 1 illustrates the structure of a server module
employing a cooling unit;
[0009] FIG. 2 illustrates a tank of a first embodiment;
[0010] FIGS. 3A and 3B illustrate the structure of the tank of the
first embodiment;
[0011] FIG. 4 illustrates the advantageous effect of the tank of
the first embodiment;
[0012] FIG. 5 illustrates a tank of a second embodiment;
[0013] FIGS. 6A and 6B illustrate the structure of the tank of the
second embodiment; and
[0014] FIG. 7 illustrates the advantageous effect of the tank of
the second embodiment.
DESCRIPTION OF EMBODIMENTS
[0015] The preferred embodiments of the present disclosure will be
described in detail with reference to the drawings.
[0016] FIG. 1 illustrates the configuration of the inside of a
server module employing a cooling unit to which the disclosed
technique is applied. A circuit board 95 on which a plurality of
CPUs 90 are mounted is disposed inside the server module 100.
Cooling jackets 92 for transferring heat from the CPUs to coolant
are attached to the CPUs 90. The cooling jackets 92 are made of
metal having good thermal conductivity, for example, copper or
aluminum.
[0017] A radiating fin 10 is disposed at an end of the inside of
the server module 100 (in the upper part of FIG. 1). On the inner
side of the radiating fin 10, a plurality of fans 70 are disposed.
The plurality of fans 70 rotate in a direction such that air is
blown toward the radiating fin 10. Air heated by the radiating fin
10 is discharged from the end of the server module 100 to the
outside of the server module 100.
[0018] The server is usually installed in a temperature controlled
room. Thus, the plurality of fans 70 may be rotated in the opposite
direction to suck in outside air through the end of the server
module 100 to cool the radiating fin 10 with the outside air. Also
in this case, a cooling effect is achieved.
[0019] A tank 40 that stores coolant is disposed inside the server
module 100. In the case of this embodiment, in order to save space,
the tank 40 is disposed on the top of the cooling jacket 92 on the
top of one of the CPUs 90. A plurality of pumps 80 are connected to
a side surface of the tank 40. Coolant pressurized by the pumps 80
is sent out from the tank 40 to a pipe 60.
[0020] In this embodiment, in order to improve reliability, not
only a single pump but a plurality of pumps are provided. If one of
the pumps brakes down and stops working, the flow of coolant may be
maintained by the other pump, and the temperature rise of
heat-generating components such as CPUs 90 may be suppressed. It is
also possible to control the number of working pumps to change the
flow rate of coolant to adjust the cooling effect according to the
operating conditions of the CPUs 90.
[0021] Coolant sent out from the tank 40 absorbs heat from the CPUs
90 in the cooling jackets 92 and is sent to the radiating fin 10
through a pipe 61. Coolant is cooled in the radiating fin 10 by the
fans 70 and is returned to the tank 40 by a pipe 62. The cooling
unit includes the tank 40, the pipe 60, the cooling jackets 92, the
pipe 61, the radiating fin 10, and the pipe 62. Coolant circulates
through these components, which form a radiating circulation loop.
By arranging this radiating circulation loop linearly and setting
the route short, coolant may be returned in a short time and the
heat radiating efficiency may be improved. The circuit board 95 is
designed centering around the CPUs 90, which are the nerve centers
of the circuit, and thus the CPUs 90 are often disposed in the
center of the circuit board 95. Thus, the radiating circulation
loop is also often disposed across the center of the circuit board
95.
[0022] For example, a propylene glycol based antifreeze is used as
coolant. However, examples of coolant are not limited to this.
Parts of the pipes 60, 61, and 62 are made of a flexible
heat-insulating material such as rubber or resin. Parts of the
pipes 60, 61, and 62 near the cooling jackets 92 are made of a
material having good thermal conductivity such as metal in order to
efficiently transfer heat from the CPUs 90 to coolant.
[0023] Next, with reference to FIG. 2, a tank 40 of a first
embodiment will be described. FIG. 2 is a transparent perspective
view of the tank 40. The pipe 62 is connected to an inlet 50 in one
of the side surfaces of the tank 40. Coolant cooled in the
radiating fin 10 is caused to flow through the pipe 62 into the
tank 40. A plurality of pumps 80 are connected to the other side
surface of the tank 40. The pumps 80 suck out coolant from the tank
40 and expel coolant to the tank 40, thereby producing a flow of
coolant. Coolant expelled from the pumps 80 is returned to the
radiating circulation loop through an outlet 52 provided in the
surface of the tank 40 to which the pumps 80 are connected, and the
pipe 60.
[0024] Next, with reference to FIGS. 3A and 3B, the structure of
the tank 40 will be described in detail. FIG. 3A is a sectional
view of the tank 40 and the pumps 80 in FIG. 2 taken along line
IIIA-IIIA and in the direction of the arrows. FIG. 3B is a
sectional view of the tank 40 and the pumps 80 in FIG. 2 taken
along line IIIB-IIIB and in the direction of the arrows.
[0025] With reference to FIG. 3A, the inside of the tank 40 is
partitioned by a partition plate 46 into two sections: a coolant
storing chamber 42 that stores coolant flowing in through the inlet
50 in the upper-left part of FIG. 3A, and a coolant mixing chamber
44 in which coolant expelled from the plurality of pumps 80 is
mixed and that is located in the upper-right part in FIG. 3A. If
the cooling unit includes only a single pump, the pump is provided
in the radiating circulation loop, and coolant is sucked out from
the radiating circulation loop and is turned to the radiating
circulation loop. However, as described above, in this embodiment,
a plurality of pumps 80 are provided in order to improve
reliability. For this reason, the coolant mixing chamber 44 for
collecting coolant expelled from the plurality of pumps 80 and
returning the collected coolant to the radiating circulation loop
has to be used. The plurality of pumps 80 are connected in parallel
to the coolant mixing chamber 44 so that if one of the pumps 80
brakes down, the flow of coolant of the other pump 80 is not
stopped.
[0026] Coolant cooled by the radiating fin 10 is caused to flow
through the pipe 62 and the inlet 50 into the coolant storing
chamber 42. The pumps 80 suck coolant through pump suction ports 54
of the coolant storing chamber 42 located below the coolant mixing
chamber 44, and pump suction pipes 82, and then expel coolant
through pump expelling pipes 84 and pump expelling ports 56 into
the coolant mixing chamber 44.
[0027] With reference to FIG. 3B, coolant expelled from the
plurality of pumps 80 is collected in the coolant mixing chamber 44
and is then discharged to the pipe 60 through the outlet 52 located
at the bottom of FIG. 3B.
[0028] In addition to coolant flowing through the radiating
circulation loop, coolant for replacing coolant lost through the
surface of rubber that makes up the pipes and the surface of resin
that makes up the pumps is stored in the tank 40.
[0029] At the stage of manufacturing the server module 100, the
radiating circulation loop is filled with coolant. The coolant
storing chamber 42 and the coolant mixing chamber 44 in the tank 40
are also filled with coolant. Coolant filling is usually performed
at room temperature. At this time, air is dissolved in coolant.
[0030] When the server module 100 operates and the cooling of the
CPUs 90 starts, the temperature of coolant rises, and air dissolved
in coolant at room temperature vaporizes to become air bubbles. The
air bubbles move through the radiating circulation loop with the
flow of coolant. If the air bubbles accumulate in the pumps 80, air
locks may arise in the pumps 80, and the ability to expel coolant
may decrease significantly.
[0031] With reference to FIG. 4, the air bubbles generated in the
radiating circulation loop move with the flow of coolant and flow
into the coolant storing chamber 42 in the tank 40. Since the air
bubbles have a lower specific gravity than coolant, the air bubbles
accumulate in a region (hereinafter referred to as air bubble
accumulating portion 48) in the upper part of the coolant storing
chamber 42 and beside the coolant mixing chamber 44. Air bubbles
accumulated in the air bubble accumulating portion 48 form an air
layer 49. Since air bubbles accumulate in the air bubble
accumulating portion 48, air bubbles are not sucked into the pumps
80 together with coolant through the pump suction ports 54 in the
lower part of the coolant storing chamber 42. Thus, according to
this embodiment, air locks of the pumps 80 may be suppressed. Since
air bubbles generated in the radiating circulation loop finally
accumulate in the coolant storing chamber 42, the amount of coolant
flowing through the radiating circulation loop is substantially
stable, and a decrease in cooling efficiency may be suppressed.
[0032] Turning to FIG. 1, the flow of coolant discharged from the
tank 40 is divided into two flows and sent through the pipe 60 to
each of the cooling jackets 92 for cooling two CPUs 90 in this
embodiment. The flows of coolant that has absorbed heat from each
CPU 90 are merged in the pipe 61 on the opposite side of the
cooling jackets 92 and sent to the radiating fin 10. Coolant cooled
in the radiating fin 10 is returned through the pipe 62 to the tank
40.
[0033] Next, with reference to FIG. 5, a tank 40A of a second
embodiment will be described. FIG. 5 is a transparent perspective
view of the tank 40A. Unlike the tank 40 according to the first
embodiment, the tank 40A of this embodiment has a structure such
that a plurality of pumps 80 are disposed on the left and right
sides of the tank 40A. By disposing a plurality of (six in this
case) pumps 80 on the left and right sides of the tank 40A, the
flow rate of coolant is increased and the cooling efficiency is
improved. The pipe 62 is connected to an inlet 50 in one of the
side surfaces of the tank 40A. Coolant cooled in the radiating fin
10 is caused to flow through the pipe 62 into the tank 40A. Three
pumps 80 are connected to each of other two side surfaces of the
tank 40A. In order to reduce the mounting height in the height
direction in the server module 100, the pumps 80 connected to the
tank 40A are inclined. In this embodiment, the pumps 80 on the left
side are inclined in a direction opposite to that of the
inclination of the pumps 80 on the right side.
[0034] The pumps 80 suck out coolant from the tank 40A and expel
coolant to the tank 40A, thereby producing a flow of coolant.
Coolant expelled from the pumps 80 is returned to the radiating
circulation loop through an outlet 52 provided in one of the
surfaces of the tank 40A to which the pumps 80 are connected, and
the pipe 60.
[0035] Next, with reference to FIGS. 6A and 6B, the structure of
the tank 40A will be described in detail. FIG. 6A is a sectional
view of the tank 40A and the pumps 80 in FIG. 5 taken along line
VIA-VIA of FIG. 5 and in the direction of the arrows (since the
pumps 80 on the left side are inclined in a direction opposite to
that of the inclination of the pumps 80 on the right side, the
sectional direction is changed). FIG. 6B is a sectional view of the
tank 40A and the pumps 80 in FIG. 5 taken along line VIB-VIB of
FIG. 5 and in the direction of the arrows.
[0036] With reference to FIG. 6A, the inside of the tank 40A is
partitioned by partition plates 46 into three sections: a coolant
storing chamber 42 that stores coolant flowing in through the inlet
50 in the center of FIG. 6A, and two coolant mixing chambers 44 in
which coolant expelled from the pumps 80 on the left and right
sides is mixed and that are located in the upper-left part and
upper-right part in FIG. 6A.
[0037] In this embodiment, six pumps 80 are provided in order to
improve reliability and cooling efficiency. For this reason, the
coolant mixing chambers 44 for collecting coolant expelled from the
plurality of pumps 80 and returning the collected coolant to the
radiating circulation loop are used. In order not to stop the flow
of coolant even if one of the pumps 80 brakes down, three pumps 80
are connected in parallel to one coolant mixing chamber 44. Three
pumps 80 are connected in parallel to one coolant mixing chamber 44
so that if one of the pumps 80 brakes down, the flows of coolant of
the other pumps 80 are not stopped.
[0038] Coolant cooled by the radiating fin 10 is caused to flow
through the pipe 62 and the inlet 50 into the coolant storing
chamber 42. The pumps 80 on the left and right sides suck coolant
through pump suction ports 54 of the coolant storing chamber 42
located below the coolant mixing chambers 44, and pump suction
pipes 82, and then expel coolant through pump expelling pipes 84
and pump expelling ports 56 into the left and right coolant mixing
chambers 44.
[0039] With reference to FIG. 6B, the left and right coolant mixing
chambers 44 communicate with each other at the bottom of FIG. 6B.
This part will hereinafter be referred to as second coolant mixing
chamber 45. Coolant expelled from the plurality of pumps 80 to the
left and right coolant mixing chambers 44 is collected in the
second coolant mixing chamber 45 and is then discharged to the pipe
60 through the outlet 52 located at the bottom of FIG. 6B.
[0040] With reference to FIG. 7, the air bubbles generated in the
radiating circulation loop move with the flow of coolant and flow
into the coolant storing chamber 42 in the tank 40A. Since the air
bubbles have a lower specific gravity than coolant, the air bubbles
accumulate in a region (hereinafter referred to as air bubble
accumulating portion 48) in the upper part of the coolant storing
chamber 42 and between the two coolant mixing chambers 44. Air
bubbles accumulated in the air bubble accumulating portion 48 form
an air layer 49. Since air bubbles accumulate in the air bubble
accumulating portion 48, air bubbles are not sucked into the pumps
80 together with coolant through the pump suction ports 54 in the
lower part of the coolant storing chamber 42. In this embodiment,
the left and right coolant mixing chambers 44 have a
cross-sectional shape inclined downward toward the inside of the
tank 40A. Since the flow path to the pump suction ports 54 becomes
narrower downward, air bubbles are kept from being sucked into the
pumps 80 even if air bubbles flow forcefully into the coolant
storing chamber 42 together with coolant owing to an increase in
the flow rate of coolant.
[0041] Owing to the above-described structure, also in this
embodiment, air locks of the pumps 80 may be suppressed. Since air
bubbles generated in the radiating circulation loop finally
accumulate in the coolant storing chamber 42, the amount of coolant
flowing through the radiating circulation loop is substantially
stable, and a decrease in cooling efficiency may be suppressed.
[0042] Turning to FIG. 1, the flow of coolant discharged from the
tank 40 is divided into two flows and sent through the pipe 60 to
each of the cooling jackets 92 for cooling two CPUs 90 in this
embodiment. The flows of coolant that has absorbed heat from each
CPU 90 are merged in the pipe 61 on the opposite side of the
cooling jackets 92 and sent to the radiating fin 10. Coolant cooled
in the radiating fin 10 is returned through the pipe 62 to the tank
40A.
[0043] All examples and conditional language recited herein are
intended for pedagogical purposes to aid the reader in
understanding the invention and the concepts contributed by the
inventor to furthering the art, and are to be construed as being
without limitation to such specifically recited examples and
conditions, nor does the organization of such examples in the
specification relate to a showing of the superiority and
inferiority of the invention. Although the embodiments of the
present invention have been described in detail, it should be
understood that the various changes, substitutions, and alterations
could be made hereto without departing from the spirit and scope of
the invention.
* * * * *