U.S. patent application number 13/607424 was filed with the patent office on 2013-11-28 for natural circulation type cooling apparatus.
This patent application is currently assigned to KABUSHIKI KAISHA TOSHIBA. The applicant listed for this patent is Satoru ABE, Hiroshi ISHII, Taihei KOYAMA, Satoshi KUROSAWA, Akio SEKIMOTO, Yuuki TSUKINARI. Invention is credited to Satoru ABE, Hiroshi ISHII, Taihei KOYAMA, Satoshi KUROSAWA, Akio SEKIMOTO, Yuuki TSUKINARI.
Application Number | 20130312937 13/607424 |
Document ID | / |
Family ID | 46851836 |
Filed Date | 2013-11-28 |
United States Patent
Application |
20130312937 |
Kind Code |
A1 |
TSUKINARI; Yuuki ; et
al. |
November 28, 2013 |
NATURAL CIRCULATION TYPE COOLING APPARATUS
Abstract
According to one embodiment, a natural circulation type cooling
apparatus includes a heat receiver with a heat receiving surface on
which an exothermic body is mounted, and containing therein a
coolant, a condenser on a horizontally lateral side of the heat
receiver, a radiator on a horizontally lateral side of the heat
receiver and on a vertically downward side of the condenser, a
vapor conduit configured to feed vapor of the coolant to an inlet
of the condenser, a condensed liquid conduit configured to feed a
condensed coolant from an outlet of the condenser to an inlet of
the heat receiver, a coolant conduit configured to feed the coolant
to an inlet of the radiator, and a circulation conduit configured
to feed the coolant from an outlet of the radiator to the inlet of
the heat receiver.
Inventors: |
TSUKINARI; Yuuki;
(Fuchu-shi, JP) ; KOYAMA; Taihei; (Tachikawa-shi,
JP) ; ABE; Satoru; (Yokohama-shi, JP) ; ISHII;
Hiroshi; (Kawasaki-shi, JP) ; KUROSAWA; Satoshi;
(Yokohama-shi, JP) ; SEKIMOTO; Akio;
(Tachikawa-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TSUKINARI; Yuuki
KOYAMA; Taihei
ABE; Satoru
ISHII; Hiroshi
KUROSAWA; Satoshi
SEKIMOTO; Akio |
Fuchu-shi
Tachikawa-shi
Yokohama-shi
Kawasaki-shi
Yokohama-shi
Tachikawa-shi |
|
JP
JP
JP
JP
JP
JP |
|
|
Assignee: |
KABUSHIKI KAISHA TOSHIBA
Tokyo
JP
|
Family ID: |
46851836 |
Appl. No.: |
13/607424 |
Filed: |
September 7, 2012 |
Current U.S.
Class: |
165/104.21 |
Current CPC
Class: |
H01L 2924/0002 20130101;
F28D 15/0266 20130101; H01L 23/427 20130101; H05K 7/20327 20130101;
H01L 2924/00 20130101; H01L 2924/0002 20130101; H05K 7/20936
20130101 |
Class at
Publication: |
165/104.21 |
International
Class: |
F28D 15/02 20060101
F28D015/02 |
Foreign Application Data
Date |
Code |
Application Number |
May 23, 2012 |
JP |
2012-117812 |
Claims
1. A natural circulation type cooling apparatus comprising: a heat
receiver comprising a heat receiving surface on which an exothermic
body is mounted, and containing therein a coolant in a liquid
phase; a condenser provided on a horizontally lateral side of the
heat receiver, and configured to condense a vapor which is
generated by the heat receiver; a radiator disposed on a
horizontally lateral side of the heat receiver and on a vertically
downward side of the condenser, and configured to cool the coolant
which is fed from the heat receiver and is heated; a vapor conduit
configured to feed the vapor of the coolant, which is generated by
the heat receiver, to an inlet of the condenser; a condensed liquid
conduit configured to feed the coolant, which is condensed, from an
outlet of the condenser to a coolant inlet of the heat receiver; a
coolant conduit configured to feed the coolant, which is heated in
the heat receiver, to an inlet of the radiator; and a coolant
circulation conduit configured to feed the coolant, which is cooled
in the radiator, from an outlet of the radiator to the coolant
inlet of the heat receiver.
2. The natural circulation type cooling apparatus of claim 1,
wherein the heat receiver comprises: a container body comprising
the heat receiving surface and an upper opening, and containing the
coolant; an upper container configured to cover the upper opening
of the container body; a plurality of partition plates provided at
intervals within the container body, and configured to partition an
inside of the container body into a plurality of containing
chambers which contain the coolant, respectively; a plurality of
baffle plates extending upward from the upper opening of the
container body, beyond a liquid level of the coolant, and
configured to restrict inflow of the coolant from each of the
containing chambers into another of the containing chambers; a
vapor outlet formed in the upper container and communicating with
the plurality of containing chambers via a space in the upper
container; a coolant inlet formed in a lower part of the container
body and communicating with the plurality of containing chambers; a
coolant outlet formed in the upper container; and a sub-flow
passage defined by the upper container and configured to guide the
coolant, which flows out of the containing chambers, to the coolant
outlet.
3. The natural circulation type cooling apparatus of claim 2,
wherein each of the partition plates comprises an upper end portion
which extends upward beyond the liquid level of the coolant and
constitutes the baffle plate.
4. The natural circulation type cooling apparatus of claim 1,
wherein the condensed liquid conduit is connected between the
outlet of the condenser and an intermediate portion of the coolant
circulation conduit.
5. The natural circulation type cooling apparatus of claim 1,
wherein the radiator comprises an inflow portion which includes the
inlet of the coolant, an outflow portion which includes the outlet
of the coolant and is located on a vertically upward side of the
inlet portion, and a plurality of radiation tubes which extend
between the inflow portion and the outflow portion and through
which the heated coolant flows.
6. The natural circulation type cooling apparatus of claim 1,
further comprising an air blower configured to blow cooling air to
the condenser and the radiator.
7. The natural circulation type cooling apparatus of claim 6,
further comprising a duct provided between the condenser and the
radiator, on the one hand, and the air blower, on the other hand,
and configured to guide the cooling air from the air blower to the
condenser and the radiator.
8. The natural circulation type cooling apparatus of claim 1,
further comprising another heat receiver including a heat receiving
surface on which an exothermic body is mounted, and containing a
coolant, wherein the two heat receivers are arranged such that the
heat receiving surfaces thereof are located in a common plane, and
the condenser and the radiator are disposed between the two heat
receivers and are disposed at lateral side parts of the heat
receivers, relative to the common plane as the heat receiving
surfaces.
9. The natural circulation type cooling apparatus of claim 1,
wherein the heat receiving surface is formed on one of surfaces of
the heat receiver, the condenser is arranged at an upper part on a
rear side of the heat receiver, which is opposite to the heat
receiving surface, and the radiator is arranged at a lower part on
the rear side.
10. The natural circulation type cooling apparatus of claim 1,
wherein the heat receiving surface is formed on one of surfaces of
the heat receiver, the condenser is arranged at an upper part on a
rear side of the heat receiver, which is opposite to the heat
receiving surface, the radiator is arranged at a lower part on the
rear side, and the condenser and the radiator are provided on a
plane which is perpendicular to the heat receiving surface of the
heat receiver.
11. The natural circulation type cooling apparatus of claim 1,
further comprising another heat receiver including a heat receiving
surface on which an exothermic body is mounted, and containing a
coolant, wherein the two heat receivers are arranged such that rear
surfaces thereof, which are opposite to the heat receiving
surfaces, are opposed to each other, the condenser is arranged at
an upper part between the two heat receivers, the radiator is
arranged at a lower part between the two heat receivers, and the
condenser and the radiator are arranged on a plane which is
perpendicular to the heat receiving surfaces of the heat receivers.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based upon and claims the benefit of
priority from Japanese Patent Application No. 2012-117812, filed
May 23, 2012, the entire contents of which are incorporated herein
by reference.
FIELD
[0002] Embodiments described herein relate generally to a cooling
apparatus applied with a natural circulation liquid cooling method,
in which a coolant circulation pump for providing an external
driving force is not used, and which cools an exothermic body such
as a semiconductor device that is used in a power converter for a
railway vehicle.
BACKGROUND
[0003] In general, a power converter for a railway vehicle
comprises an exothermic body such as a semiconductor device, and a
cooling apparatus for cooling such an exothermic body. As a cooling
method of a large-capacity cooling apparatus, a boiling cooling
method and a forced circulation liquid cooling method are applied.
In a cooling apparatus to which the former cooling method is
applied, there are, because of the device structure, such
restrictions on disposition that a high-temperature unit is
disposed on a lower side and a low-temperature unit is disposed on
an upper side. In addition, it is the fact that there is an
international trend toward complete disuse of a Freon-based coolant
which is used for this cooling method. On the other hand, in a
cooling apparatus to which the latter cooling method is applied,
there are many structural elements which accompany the cooling
system, such as a circulation pump, conduits, a fluid reservoir
tank, a heat exchanger, etc., and there are demerits such as an
increase in volume for installation and an increase in cost due to
this.
[0004] In recent years, there has been proposed a technique for a
cooling method, in which the demerits of both of the
above-described cooling methods are eliminated. In this technique,
a coolant is naturally circulated in the system. Specifically,
buoyancy of boiling bubbles, which are generated by the exothermic
body, such as a semiconductor device, is used as a circulation
driving force. According to this natural circulation cooling
method, a passive cooling system, which uses no external driving
force, can be constructed.
[0005] In a cooling apparatus using the above-described natural
circulation cooling method, a heat exchanger for condensing a
generated vapor is disposed on an upper side of a heat receiver to
which the exothermic body is attached, and a radiator is disposed
on a lateral side of the heat receiver. In the case of this
structure, because of the positional configuration within the power
converter, there are cases where the direction of disposition of
the cooling apparatus is restricted due to problems with the space
occupied by the apparatus, the equipment size, and the mounting of
the apparatus. Hence, the degree of freedom of design of the entire
apparatus system decreases.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 is a side view which schematically illustrates a
railway vehicle including a natural circulation type cooling
apparatus according to a first embodiment;
[0007] FIG. 2 is a plan view which schematically illustrates an
underflow side of the railway vehicle;
[0008] FIG. 3 is a front view which schematically illustrates the
cooling apparatus according to the first embodiment;
[0009] FIG. 4 is a partially cutaway perspective view of a heat
receiver of the cooling apparatus;
[0010] FIG. 5 is a cross-sectional view of the heat receiver, taken
along line A-A in FIG. 4;
[0011] FIG. 6 is a cross-sectional view of the heat receiver, taken
along line B-B in FIG. 4;
[0012] FIG. 7 is a front view which schematically illustrates a
natural circulation type cooling apparatus according to a second
embodiment;
[0013] FIG. 8 is a side view which schematically illustrates a
natural circulation type cooling apparatus according to a third
embodiment;
[0014] FIG. 9 is a cross-sectional view showing an internal
structure in an upper part of a heat receiver of the cooling
apparatus according to the third embodiment;
[0015] FIG. 10 is a side view which schematically illustrates a
natural circulation type cooling apparatus according to a fourth
embodiment;
[0016] FIG. 11 is a side view which schematically illustrates a
natural circulation type cooling apparatus according to a fifth
embodiment;
[0017] FIG. 12 is a side view which schematically illustrates a
natural circulation type cooling apparatus according to a sixth
embodiment; and
[0018] FIG. 13 is a side view which schematically illustrates a
natural circulation type cooling apparatus according to a seventh
embodiment.
DETAILED DESCRIPTION
[0019] Various embodiments will be described hereinafter with
reference to the accompanying drawings. In general, according to
one embodiment, a natural circulation type cooling apparatus
comprises: a heat receiver comprising a heat receiving surface on
which an exothermic body is mounted, and containing therein a
coolant in a liquid phase; a condenser provided on a horizontally
lateral side of the heat receiver, and configured to condense a
vapor which is generated by the heat receiver; a radiator disposed
on a horizontally lateral side of the heat receiver and on a
vertically downward side of the condenser, and configured to cool
the coolant which is fed from the heat receiver and is heated; a
vapor conduit configured to feed the vapor of the coolant, which is
generated by the heat receiver, to an inlet of the condenser; a
condensed liquid conduit configured to feed the coolant, which is
condensed, from an outlet of the condenser to a coolant inlet of
the heat receiver; a coolant conduit configured to feed the
coolant, which is heated in the heat receiver, to an inlet of the
radiator; and a coolant circulation conduit configured to feed the
coolant, which is cooled in the radiator, from an outlet of the
radiator to the coolant inlet of the heat receiver.
First Embodiment
[0020] FIG. 1 and FIG. 2 are, respectively, a side view and a plan
view which schematically illustrate a railway vehicle including a
natural circulation type cooling apparatus according to a first
embodiment. The railway vehicle comprises a truck 12 provided with
wheels 14, and a vehicle body 16 supported on the truck 12. A
traction motor 18 is mounted on the truck 12 in the vicinity of the
wheels 14. The traction motor 18 transmits a torque to the wheels
14 via a gear box and a coupling, which are not shown. The wheels
14 are placed on rails 13. Various devices including a power
converter 20 are equipped under the floor of the vehicle body 16. A
natural circulation type cooling apparatus 10 according to the
embodiment is configured, for example, as a cooling apparatus for
cooling semiconductor devices (exothermic body) which constitute
the power converter 20, and is disposed under the floor of the
vehicle body 16.
[0021] FIG. 3 is a front view schematically showing the structure
of the entirety of the cooling apparatus 10. FIG. 4, FIG. 5 and
FIG. 6 are, respectively, a perspective view and cross-sectional
views showing a heat receiver of the cooling apparatus 10. As shown
in FIG. 1 to FIG. 3, the cooling apparatus 10 comprises a heat
receiver 22 which cools semiconductor devices by receiving heat
from the semiconductor devices, a condenser 24, a radiator 26, and
a plurality of conduits which interconnect these components. In the
embodiment, the cooling apparatus 10 further comprises an air
blower 28.
[0022] The heat receiver 22 is provided, for example, within a
housing 21 of the power converter 20, and is positioned in a
substantially vertical plane. The condenser 24 and radiator 26 are
arranged in the vertical plane common with the heat receiver 22, or
in another vertical plane parallel to this vertical plane. The
condenser 24 is provided on a horizontally lateral side of the heat
receiver 22. The radiator 26 is arranged on the horizontally
lateral side of the heat receiver 22, and on a vertically downward
side of the condenser 24. The air blower 28 is opposed to the rear
side of the condenser 24 and radiator 26.
[0023] As shown in FIG. 3 to FIG. 6, the heat receiver 22 includes
a container body 30 having an elongated rectangular box shape, and
an upper container 32 of a rectangular box shape, which covers an
upper part of the container body 30 and forms a sub-flow passage
which will be described later. One or both of major surfaces of the
container body 30 constitute a heat receiving surface 30a. A
plurality of semiconductor devices 36, for example, two
semiconductor devices 36, which are exothermic bodies, are mounted
on the heat receiving surface 30a. The semiconductor devices 36
constitute a part of the power converter 20.
[0024] The container body 30 is formed in a predetermined size in
accordance with the cooling capability of the cooling apparatus,
and a predetermined amount of liquid-phase coolant 34 is sealed in
the container body 30. As the coolant 34, use is made of pure
water, a hydrocarbon-based coolant, an ammonia aqueous solution, an
antifreeze liquid (ethylene glycol aqueous solution, propylene
glycol aqueous solution, etc.), or a heat-accumulation
microcapsule. In general, a chemically stable coolant is used, and
the coolant preferably has thermophysical properties of high
evaporation latent heat and thermal conductivity, and a low
viscosity coefficient.
[0025] As the material for forming the heat receiving surface 30a
of the heat receiver 22, aluminum or brass is used in accordance
with the coolant that is applied. In addition, it is possible to
apply a material in which heat transfer is promoted by reforming
the heat receiving surface 30a with an external physical treatment
such as beam irradiation or flame spray coat shaping.
[0026] A plurality of partition plates 38 are provided in the
container body 30 of the heat receiver 22, so as to form desired
flow passages or containing chambers. The partition plates 38 are
arranged in the vertical direction within the container body 30,
and at predetermined intervals in the horizontal direction.
Containing chambers 40 which contain the coolant 34, or passages,
are formed between mutually neighboring partition plates 38 or
between the partition plates and side walls of the container body
30. A lower end of each partition plate 38 is slightly spaced apart
from a bottom wall of the container body 30, and thereby the plural
containing chambers 40 communicate with each other in the lower
part within the container body 30.
[0027] In addition, an upper end portion of each partition plate 38
extends upward, beyond an upper opening 30b of the container body
30, and is located within the upper container 32. The upper end
portions of the partition plates 38 form baffle plates 42. The
baffle plates 42 restrain the coolant 34, which flows out of each
containing chamber 40 of the container body 30, from flowing into
the neighboring containing chambers 40. In the meantime, the
structure of the baffle plate 42 is not limited to the structure in
which the baffle plate 42 is formed integral with the partition
plate 38. The baffle plate 42 may be configured such that a
separately formed baffle plate is fixed to the partition plate
38.
[0028] By the upper container 32, a sub-flow passage 44 is formed
around the upper opening 30b of the container body 30. The coolant
34, which is heated and flows out of each containing chamber 40,
flows into the sub-flow passage 44, and is fed to a coolant outlet
(to be described later) through the sub-flow passage 44. The
sub-flow passage 44 may be configured to be inclined at a desired
angle to the coolant outlet side, so that the coolant may
efficiently be fed to the coolant outlet.
[0029] A vapor exhaust port 46 is formed in a ceiling wall of the
upper container 32, and this vapor exhaust port 46 communicates
with the plural containing chambers 40 via a space within the upper
container 32. A coolant outlet 48 is formed in a side wall of the
upper container 32, and this coolant outlet 48 communicates with
the sub-flow passage 44. A coolant inlet 50 is formed in a bottom
wall of the container body 30, and this coolant inlet 50
communicates with the plural containing chambers 40.
[0030] As shown in FIG. 3, the condenser 24 includes a conduit 52
which extends in a bellows shape and flows vapor, and a plurality
of radiation fins 54 which are disposed directly or indirectly on
the periphery of the conduit 52. The conduit 52 includes an inlet
56a which is located at one end of the conduit 52, and an outlet
56b which is located at the other end of the conduit 52. The outlet
56b is located on a vertically downward side of the inlet 56a.
[0031] The inlet 56a of the conduit 52 is connected to the vapor
exhaust port 46 of the heat receiver 22 via a vapor conduit 58. The
outlet 56b of the conduit 52 is directly connected to the coolant
inlet 50 of the heat receiver 22 via a condensed liquid conduit 60,
or is connected to the coolant inlet 50 via a coolant circulation
conduit 70 (to be described later). The condenser 24 cools the
vapor which flows in the conduit 52, condenses the vapor into a
coolant liquid, and discharges the coolant liquid from the outlet
56b to the condensed liquid conduit 60. The discharged coolant
liquid is returned to the heat receiver 22 through the condensed
liquid conduit 60.
[0032] The condenser 24 may be configured or shaped such that the
inside of the condenser 24 is coated with a paint with high water
repellency in order to promote heat transfer with condensation, and
an inclination is provided make it easier for the generated
condensed liquid to flow downward.
[0033] As shown in FIG. 3 and FIG. 4, the radiator 26 includes a
plurality of radiation tubes 62 which extend in the vertical
direction and are juxtaposed in the horizontal direction, an inflow
portion 64a which communicates with lower ends of the radiation
tubes 62, an outflow portion 64b which communicates with upper ends
of the radiation tubes 62, an inlet 66a which is provided at the
inflow portion 64a, and an outlet 66b which is provided at the
outflow portion 64b. Radiation fins may be provided on peripheries
of the radiation tubes 62.
[0034] The inlet 66a of the inflow portion 64a is connected to the
coolant outlet 48 of the heat receiver 22 via a coolant conduit 68.
The inlet 66a is located on a vertically downward side of the
coolant outlet 48 of the heat receiver 22. The outlet 66b of the
outflow portion 46b is connected to the coolant inlet 50 of the
heat receiver 22 via the coolant circulation conduit 70.
[0035] If a high-temperature coolant is fed from the heat receiver
22 to the radiator 26 via the coolant conduit 68, the radiator 26
flows the coolant upward from the inflow portion 64a through the
plural radiation tubes 62 and, during this time, releases the heat
of the coolant to the outside air and cools the coolant via the
radiation tubes. Further, the radiator 26 feeds out the cooled
coolant to the coolant circulation conduit 70 via the outflow
portion 64b. The discharged coolant is returned to the heat
receiver 22 through the coolant circulation conduit 70. In the
present embodiment, the condensed liquid conduit 60 is connected to
an intermediate portion of the coolant circulation conduit 70.
Thereby, the coolant liquid, which has been discharged from the
condenser 24, is fed to the heat receiver 22 via the condensed
liquid conduit 60 and coolant circulation conduit 70.
[0036] As shown in FIG. 1 to FIG. 3, the air blower 28 is disposed
to be opposed to the rear side of the condenser 24 and radiator 26,
and the air blower 28 may be configured to be directly attached to
the condenser 24 and radiator 26, or may be configured to be
connected to the condenser 24 and radiator 26 via an air duct 72.
The air blower 28 feeds a cooling wind to the condenser 24 and
radiator 26, and facilitates cooling of the condenser 24 and
radiator 26. When the air duct 72 is disposed, the amount of air of
the air blower 28 can be increased. In addition the condenser 24
and radiator 26 may be configured to be disposed in a manner to
protrude to the outside of the vehicle body, thereby to make use of
a traveling wind, which is caused by traveling, as a cooling
wind.
[0037] The cooling operation of the cooling apparatus 10 having the
above-described structure is described.
[0038] As shown in FIG. 3 and FIG. 5, when the semiconductor
devices 36 mounted on the heat receiving surface 30a of the heat
receiver 22 are activated and produce heat, the heat conducts
through the heat receiving surface 30a and heats, by heat transfer,
the coolant 34 that is sealed in the container body 30 of the heat
receiver 22. As the amount of loss in the semiconductor devices 36
increases, the coolant 34 reaches a saturation temperature and
starts boiling. Bubbles 101, which are generated by boiling,
produce a driving force by a difference in density from an ambient
liquid. Specifically, buoyancy by the bubbles 101 generates an
upward stream in the container body 30. With the bubbles 101
rising, the ambient coolant 34 also rises accordingly. In the upper
part of the container body 30, the coolant 34 has a mixed phase of
a gas phase and a liquid phase, that is, a gas/liquid two-phase
fluid state.
[0039] On the other hand, a vapor 102, which is generated by the
heat receiver 22, is fed to the condenser 24 via the vapor conduit
58. In the condenser 24, heat exchange is performed by the
radiation fins 54 that are disposed on the periphery thereof, and
the vapor 102 is condensed into liquid. The condensed liquid of
coolant is fed to the lower part of the heat receiver 22 via the
condensed liquid conduit 60 and coolant circulation conduit 70.
[0040] As shown in FIG. 4 and FIG. 6, at the same time, the
high-temperature, gas/liquid two-phase coolant 34 at the upper part
of the heat receiver 22 flows out of the upper opening 30b of the
container body 30, with the upward stream thereof becoming a
circulation driving stream. The outflow coolant 34 is guided to the
sub-flow passage 44, and is further fed to the inflow portion 64a
of the radiator 26 from the sub-flow passage 44 via the coolant
conduit 68. At this time, the baffle plates 42, which are provided
at the upper part of the container body 30, prevent the
high-temperature coolant from flowing back into the heat receiver,
that is, from flowing back into the neighboring containing chamber
40. Thereby, the coolant, which flows out of the heat receiver 22,
can efficiently be fed to the coolant conduit 68 via the sub-flow
passage 44.
[0041] As shown in FIG. 3, the high-temperature coolant 34, which
has flowed in the radiator 26, flows upward through the radiation
tubes 62 and is fed to the outflow portion 64b, and, during this
time, the heat is dissipated and the coolant 34 is cooled. The
temperature of the coolant, which flows in from the lower part of
the radiator 26, is high, and the temperature of the upper part
within the radiator 26 is relatively low. Thus, by convection due
to a difference in density, a heat current moves from the lower
part to the upper part within the radiation tubes 62 of the
radiator 26, and the coolant also flows upward. The cooled coolant
is fed out to the coolant circulation conduit 70 from the outflow
portion 64b, and is fed to the heat receiver 22 via the coolant
circulation conduit 70.
[0042] The condenser 24 and radiator 26 are forcibly air-cooled as
one body by cooling air 31 from the air blower 28 which is disposed
outside. In this manner, in the cooling apparatus 10, a natural
circulation stream is induced by the circulation loop structure,
without external driving. As has been described above, the heat of
the semiconductor devices 36 is absorbed by the heat receiver 22
and coolant 34, and the semiconductor devices 36 are cooled.
[0043] According to the natural circulation type cooling apparatus
10 with the above-described structure, the heat produced from the
semiconductor devices 36, which are attached to the heat receiving
surface 30a of the heat receiver 22, is transferred to the coolant
34 within the heat receiver 22 by heat conduction and heat
transfer. When the coolant 34 in the heat receiver 22 has reached a
predetermined saturation temperature due to an increase of loss in
the semiconductor devices 36, the coolant 34 starts boiling. At
this time, since the evaporation latent heat, that is, the latent
heat that is removed when the coolant evaporates, is remarkably
higher than in the case of usual sensible heat transfer, high-level
heat transfer can be performed. By the effect of buoyancy of
bubbles 101 which are generated by the boiling, an upward stream
occurs and a circulation stream is induced within the apparatus.
The generated vapor 102 is fed to the condenser 24 via the vapor
conduit 58, and is condensed. Thereby, it is possible to suppress
an increase in pressure within the apparatus due to the generation
of vapor, and an increase in saturation temperature value of the
coolant 34 due to the increase in pressure, and to maintain a
circulation stream of coolant at a desired temperature level.
[0044] The inside of the cooling apparatus is kept in a
reduced-pressure sealed state, the saturation temperature value of
the coolant 34 is lowered, and boiling is started earlier. Thereby,
it is possible to satisfy a tolerable temperature or below of the
semiconductor devices 36. Furthermore, the coolant 34, which has
been fed out via the coolant conduit 68, is subjected to heat
exchange by the radiator 26, is reduced in temperature, and is
circulated once again into the heat receiver 22 in a state in which
the coolant 34 has a desired subcool degree. Thus, it is also
possible to suppress burn-out on the heat conduction surface within
the heat receiver 22, and to increase a heat-removal limit value.
Thereby, the cooling apparatus can exhibit a good radiation
capability.
[0045] By disposing the condenser and radiator on the horizontally
lateral side of the heat receiver 22, it is possible to relax
restrictions on disposition of the cooling apparatus and to reduce
the size of the cooling apparatus. The inflow portion of the
condenser 24 is in a high-temperature state due to the vapor.
Conversely, the outflow portion of the condenser 24 communicates
with the coolant circulation conduit through which the coolant
cooled by the radiator 26 flows. Hence, a pressure difference tends
to easily occur between the inlet and outlet of the condenser 24,
the amount of inflow vapor to the condenser can be increased, the
coolant can efficiently be condensed and circulated, and the
cooling capability can be enhanced. When the flow amount of coolant
is small, the heat transfer is promoted within the radiator, and
the circulation of coolant can be stabilized.
[0046] From the above, there can be obtained a natural circulation
type cooling apparatus, which can relax restrictions on disposition
and realize reduction in size, and can exhibit a good heat
radiation capability.
[0047] Next, natural circulation type cooling apparatuses according
to other embodiments will be described.
[0048] In the embodiments to be described below, the structural
parts, which are identical or equivalent to those in the
above-described first embodiment, are denoted by like reference
numerals, and a detailed description is omitted.
Second Embodiment
[0049] FIG. 7 shows a natural circulation type cooling apparatus 10
according to a second embodiment.
[0050] As shown in FIG. 7, according to the second embodiment, the
natural circulation type cooling apparatus 10 is configured to
adapt to a case of cooling a plurality of semiconductor devices 36.
Specifically, the cooling apparatus 10 includes two heat receivers
22, and the heat receivers 22 are juxtaposed on the same plane.
Semiconductor devices 36 are mounted on the heat receiving surface
30a of each heat receiver 22. The heat receiving surfaces 30a of
the two heat receivers 22 are located on the same plane. The
condenser 24 and radiator 26 are disposed between the two heat
receivers 22, and are located on substantially the same plane as
the heat receiving surfaces 30a of the heat receivers 22. Each heat
receiver 22 is connected to the condenser 24 and radiator 26 via
the vapor conduit 58 and coolant circulation conduit. Two outlets
of the condenser 24 are connected to coolant circulation conduits
via condensed liquid conduits 60. Specifically, one condenser 24
and one radiator 26 are provided for the two heat receivers 22. In
addition, the condenser 24 and radiator 26 are handled as one body,
and the air blower 28 is disposed on the outside, immediately near
them, or via an air duct.
[0051] In the present embodiment, although not illustrated, such a
configuration may be adopted that a plurality of cooling
apparatuses 10 are disposed in parallel, these cooling apparatuses
10 are assembled as one module, and the air blower 28 is disposed
on the outside thereof.
[0052] In the meantime, the other structure of the cooling
apparatus and the structure of each structural element are
identical to those in the above-described first embodiment.
[0053] According to the cooling apparatus 10 with the
above-described structure, the two heat receivers 22 are disposed
on both sides of the condenser 24 and radiator 26. Thereby, the
vapors 102, which are fed out of the heat receivers 22, come
together from the two vapor conduits 58 and flow in the condenser
24. In addition, the high-temperature coolants 34, which flow out
of the heat receivers 22, flow in the radiator 26 via two condensed
liquid conduits 60, and are subjected to heat exchange by the
radiator 26. Thereafter, the coolant 34 in the subcool state
branches into two, and the branched coolants 34 return to the heat
receivers 22 via coolant circulation conduits 70, thus performing a
circulation loop operation.
[0054] In addition, by disposing the plural cooling apparatuses 10
in parallel, the condenser 24 and radiator 26, which are disposed
at the central part, can be forcibly air-cooled in the state in
which the condenser 24 and radiator 26 are integrated as one body.
In this case, control is executed by varying the output of the air
blower 28 in accordance with the magnitude in amount of radiation
heat. The other operations are the same as in the first
embodiment.
[0055] According to the cooling apparatus 10 of the second
embodiment, one condenser 24 and one radiator 26 are disposed for
two heat receivers 22, and thereby an efficient and good radiation
capability can be exhibited. In addition, the volume of the
apparatus, that is, the space for mounting, relative to the
radiation capability of the cooling apparatus, can be reduced.
Furthermore, by disposing the plural cooling apparatuses in
parallel and blowing the cooling air 31 by the air blower 28, the
cooling efficiency of the cooling apparatuses, relative to the
number of semiconductor devices 36, can be improved, and the size
and cost of the cooling apparatus can be reduced. Besides, in the
second embodiment, too, the same advantageous effects as with the
above-described first embodiment can be obtained.
Third Embodiment
[0056] FIG. 8 is a side view which illustrates a natural
circulation type cooling apparatus according to a third embodiment,
and FIG. 9 is a cross-sectional view showing a structure of an
upper part of a heat receiver.
[0057] According to the third embodiment, the condenser 24 and
radiator 26 of the cooling apparatus 10 are disposed on the rear
side of the heat receiver 22, the condenser 24 is disposed on the
upper side, and the radiator 26 is disposed under the condenser 24.
The air blower 28 for cooling the condenser 24 and radiator 26 is
disposed to be opposed to the condenser 24 and radiator 26, and the
air blower 28 air-cools the condenser 24 and radiator 26 as one
body. Although not illustrated, such a configuration may be adopted
that the condenser 24 and radiator 26 are laterally arranged in
parallel, relative to the heat receiving surface 30a of the heat
receiver 22 on which the semiconductor devices 36 are mounted, and
the condensed liquid, which flows out of the condenser 24, directly
flows down into the coolant circulation conduit 70. In this case,
in order to prevent the subcool coolant 34, which flows out of the
radiator 26, from flowing back to the condenser 24, a check vale
may be disposed in the coolant circulation conduit 70.
[0058] In the meantime, the other structure of the cooling
apparatus and the structure of each structural element are
identical to those in the above-described first embodiment.
[0059] According to the cooling apparatus 10 with the
above-described structure, the vapor generated by the heat receiver
22 and the high-temperature gas/liquid two-phase coolant 34 are fed
out, respectively, to the condenser 24 and radiator 26 which are
disposed on the rear side of the heat receiver 22. In this case, as
shown in FIG. 9, such a configuration is adopted that when the
high-temperature gas/liquid two-phase coolant 34, which has flowed
out of the upper opening of the heat receiver 22, flows from the
containing chambers 40 which are partitioned by the partition
plates 38, the coolant 34 flows only a sub-flow passage 44 which
faces an opposite surface to the heat receiving surface 30a to
which the semiconductor devices 36 are attached. Thus, the outflow
coolant 34 can easily be caused to flow into the radiator 26 via
the coolant conduit 68.
[0060] The air blower 28 for air-cooling the condenser 24 and
radiator 26 as one body is disposed on the rear side of the
condenser 24 and radiator 26. The cooling air 31 is blown not only
to the condenser 24 and radiator 26, but also to that surface of
the heat receiver 22, which is opposite to the heat receiving
surface 30a to which the semiconductor devices 36 are attached. The
operations of the other elements are the same as in the first
embodiment.
[0061] According to the cooling apparatus 10 with the
above-described structure, the condenser 24 and radiator 26 are
disposed on the rear side of the heat receiver 22. Thereby, the
size of the apparatus in the horizontal direction, relative to the
heat receiving surface 30a for semiconductor devices 36 of the heat
receiver 22, can be reduced. In addition, by making the baffle
plates 42 project from the liquid level in the heat receiver 22,
the high-temperature gas/liquid two-phase coolant 34 is prevented
from flowing back to the heat receiver 22, and can be fed out to
the radiator 26 via the coolant conduit 68. Thus, since baffle
plates, which are provided at the upper part of the heat receiver
22, are needless, the local pressure loss within the apparatus can
be reduced, and the circulation efficiency of the coolant 34 can be
improved. Therefore, the apparatus, as a whole, can maintain a
desired radiation capability, and can suppress an increase in
pressure within the apparatus. Besides, in the third embodiment,
too, the same advantageous effects as with the above-described
first embodiment can be obtained.
Fourth Embodiment
[0062] FIG. 10 schematically illustrates a natural circulation type
cooling apparatus according to a fourth embodiment. As shown in
FIG. 10, in a cooling apparatus 10 according to the fourth
embodiment, the condenser 24 and radiator 26 are disposed on the
rear side of the heat receiver 22, and the condenser 24 is disposed
at the upper part and the radiator 26 is disposed at the lower
part. The condenser 24 and radiator 26 are provided on a plane
which is perpendicular to the heat receiver 22. The air blower 28
is disposed to be opposed to the condenser 24 and radiator 26 on
the rear side of the heat receiver 22, so that cooling air may flow
through both the condenser 24 and radiator 26. In this case, a
plurality of cooling apparatuses 10 may be arranged in parallel, so
that each individual condenser 24 and radiator 26 may be air-cooled
as one body by one air blower 28, and the plural individual
condensers 24 and radiators 26 may be air-cooled batchwise at the
same time.
[0063] In the meantime, the other structure of the cooling
apparatus and the structure of each structural element are
identical to those in the above-described first embodiment.
[0064] According to the cooling apparatus 10 with the
above-described structure, the condenser 24 and radiator 26 are
air-cooled as one body, and the cooling air 31 by the air blower 28
flows through the condenser 24 and radiator 26, and flows in a
plane direction which is parallel to the rear surface of the heat
receiver 22 and to the heat receiving surface 30a to which the
semiconductor devices 36 are attached. In the case where plural
cooling apparatuses 10 are arranged in parallel, the cooling air 31
flows through each condenser 24 and radiator 26.
[0065] According to the above-described structure, the same
advantageous effects as with the above-described third embodiment
can be obtained, and the cooling air 31 can be flown to the heat
receiver 22 from the lateral surface side. Thus, many similar
cooling apparatuses can easily be arranged in parallel on this
lateral surface side. In addition, since may cooling apparatuses
can be cooled batchwise by one air blower 28, the size and weight
of the entire apparatus can be reduced. Besides, the same
advantageous effects as with the first embodiment can be
obtained.
Fifth Embodiment
[0066] FIG. 11 schematically illustrates a natural circulation type
cooling apparatus according to a fifth embodiment. As shown in FIG.
11, a cooling apparatus 10 according to the fifth embodiment
includes two heat receivers 22 which are disposed to be opposed to
each other, and a condenser 24 and a radiator 26 which are provided
between the heat receivers 22, that is, on the rear sides of both
heat receivers 22. The condenser 24 and radiator 26 are provided on
a plane which is perpendicular to the heat receivers 22, and the
condenser is 24 is disposed at the upper part and the radiator 26
is disposed at the lower part. In the heat receiver 22, no
semiconductor device 36 is mounted on that surface of the heat
receiver 22, which is located on the side facing the condenser 24
and radiator 26, that is, on the rear surface of the heat receiver
22. Semiconductor devices 36 are mounted on only the heat receiving
surface 30a on the opposite side. The same applies to the structure
of the other heat receiver 22. The air blower 28 is disposed to be
opposed to the condenser 24 and radiator 26.
[0067] In the case where many semiconductor devices 36 are mounted
and there are restrictions on disposition in the vertical
direction, such a configuration is adopted that plural condensers
24 and radiators 26 are disposed in parallel in the horizontal
direction, the air blower 28 is disposed on the lateral side, and
the plural condensers 24 and radiators 26 are air-cooled as one
body. In the case of the same condition as above and in the case
where there are restrictions on disposition in the horizontal
direction, such a configuration may be adopted that plural
condensers 24 and radiators 26 are disposed in parallel in the
vertical direction and are air-cooled as one body.
[0068] In each of the many cooling apparatuses 10 which are
arranged in parallel as described above, vapors 102, which are
generated from two heat receivers 22, are condensed into liquid in
the condenser 24 and the liquid flows down to the inlets of the
heat receivers 22. In addition, the coolant 34, which has become a
high-temperature gas/liquid two-phase fluid in the heat receivers
22, is fed out to the inlet of radiator 26 via coolant conduits 68,
and is subjected to heat exchange in the radiator. The coolant,
which has transitioned into a subcool state by the lowering in
temperature, flows back to both heat receivers 22. In the many
cooling apparatuses that are arranged in parallel, the air blower
28 is disposed and heat exchange with outside air is performed by
forced air-cooling. In the meantime, when there are restrictions on
disposition in the vertical direction, many apparatuses are
arranged in the horizontal direction, the air blower 28 is disposed
on the lateral side and caused to blow air, and exhaust air is let
to escape to the outside of the lateral parts of the
apparatuses.
[0069] According to the cooling apparatus 10 of the fifth
embodiment, the condenser 24 and radiator 26 are disposed on the
rear sides of the two heat receivers 22, that is, the condenser 24
and radiator 26 are interposed between the two heat receivers 22.
Thereby, the apparatus size in the horizontal direction can be
reduced. In this structure, even in the case where there are
restrictions on disposition of the apparatus, many apparatuses may
be disposed in parallel in the horizontal direction or vertical
direction, and the degree of freedom of design can be enhanced,
relative to the increase in number of semiconductor devices. In
addition, by disposing the air blower 28 on the lateral surface
side or bottom surface side of the condenser 24 and radiator 26,
the degree of freedom of disposition of the external air blower can
also be enhanced.
[0070] In the above structure, not only the condenser 24 and
radiator 26 can be cooled, but also air can be blown to the heat
receivers 22. Thus, the temperature level in the cooling apparatus
can be lowered, and the tolerable temperature of semiconductor
devices can further be lowered. Moreover, by setting the coolant 34
in the heat receiver 22 in the subcool state, the heat-removal
limit value can also be increased. Besides, in the fifth
embodiment, too, the same advantageous effects as with the first
embodiment can be obtained.
Sixth Embodiment
[0071] FIG. 12 schematically illustrates a natural circulation type
cooling apparatus according to a sixth embodiment. As shown in FIG.
12, a cooling apparatus 10 according to the sixth embodiment
includes a heat receiver 22, a condenser 24 and a radiator 26,
which are provided on the same plane. These components are disposed
closer to each other and are constructed as a unit. In the sixth
embodiment, the other structure of the cooling apparatus and the
structure of each structural element are identical to those in the
above-described first embodiment.
[0072] According to the above structure, the same advantageous
effects as with the above-described first embodiment can be
obtained, and the size and weight of the apparatus can be reduced
by constructing the apparatus as a single unit.
[0073] FIG. 13 schematically illustrates a railway vehicle in which
a natural circulation type cooling apparatus according to a seventh
embodiment is mounted. According to this embodiment, a heat
receiver 22 of a cooling apparatus 10 is disposed within a housing
21 of a power converter 20 which is provided under the floor of the
vehicle body 16, and a plurality of semiconductor devices, which
are exothermic bodies, are mounted on the heat receiving surface of
the heat receiver 22. A condenser 24 and a radiator 26 of the
cooling apparatus 10 are disposed on a horizontally lateral side of
the heat receiver 22, on the outside of the housing 21. The vehicle
body 16 includes an air duct 80 for guiding a traveling wind caused
by traveling, and the condenser 24 and radiator 26 are disposed in
the air duct 80. Thereby, the condenser 24 and radiator 26 are
cooled as one body by the traveling wind flowing in the air duct
80. In this case, the air blower 28 may be dispensed with.
[0074] The other structure of the cooling apparatus 10 is identical
to that of the above-described first embodiment. According to the
cooling apparatus having this structure, the same advantageous
effects as with the first embodiment can be obtained. Moreover, the
air blower can be dispensed with, and the manufacturing cost and
the space for installation can be reduced.
[0075] While certain embodiments have been described, these
embodiments have been presented by way of example only, and are not
intended to limit the scope of the inventions. Indeed, the novel
embodiments described herein may be embodied in a variety of other
forms; furthermore, various omissions, substitutions and changes in
the form of the embodiments described herein may be made without
departing from the spirit of the inventions. The accompanying
claims and their equivalents are intended to cover such forms or
modifications as would fall within the scope and spirit of the
inventions.
[0076] The exothermic body, which is a target of cooling of the
cooling apparatus, is not limited to a semiconductor device of a
power converter, and may be other exothermic bodies. The material,
of which the heat receiver and heat receiving surface are formed,
is not limited to the examples in the above-described embodiment,
and may be selected from various materials.
* * * * *