U.S. patent application number 14/372618 was filed with the patent office on 2014-12-18 for heat transport apparatus.
This patent application is currently assigned to Furukawa Electric Co., Ltd.. The applicant listed for this patent is Furukawa Electric Co., Ltd.. Invention is credited to Takeshi Hirasawa, Masami Ikeda, Yuichi Kimura, Toshiaki Nakamura, Mamoru Shimada.
Application Number | 20140367074 14/372618 |
Document ID | / |
Family ID | 48873527 |
Filed Date | 2014-12-18 |
United States Patent
Application |
20140367074 |
Kind Code |
A1 |
Hirasawa; Takeshi ; et
al. |
December 18, 2014 |
Heat Transport Apparatus
Abstract
A heat transport apparatus that is thermally connectable to an
object to be temperature adjusted includes a plurality of heat
pipes thermally connected along a heat transport direction to form
a heat transport path. The heat transport apparatus is used under
an environment at or below a melting point of a working fluid of at
least one heat pipe among the plurality of heat pipes.
Inventors: |
Hirasawa; Takeshi; (Tokyo,
JP) ; Ikeda; Masami; (Tokyo, JP) ; Kimura;
Yuichi; (Tokyo, JP) ; Shimada; Mamoru; (Tokyo,
JP) ; Nakamura; Toshiaki; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Furukawa Electric Co., Ltd. |
Tokyo |
|
JP |
|
|
Assignee: |
Furukawa Electric Co., Ltd.
Tokyo
JP
|
Family ID: |
48873527 |
Appl. No.: |
14/372618 |
Filed: |
January 24, 2013 |
PCT Filed: |
January 24, 2013 |
PCT NO: |
PCT/JP2013/051444 |
371 Date: |
July 16, 2014 |
Current U.S.
Class: |
165/104.26 |
Current CPC
Class: |
F28D 15/0275 20130101;
F28D 15/06 20130101; H01M 10/6552 20150401; F28F 2265/14 20130101;
Y02E 60/10 20130101; F28D 15/04 20130101 |
Class at
Publication: |
165/104.26 |
International
Class: |
F28D 15/04 20060101
F28D015/04; F28D 15/06 20060101 F28D015/06 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 27, 2012 |
JP |
2012-015031 |
Claims
1. A heat transport apparatus that is thermally connectable to an
object to be temperature adjusted, comprising: a plurality of heat
pipes thermally connected along a heat transport direction to form
a heat transport path, the heat transport apparatus being used
under an environment at or below a melting point of a working fluid
of at least one heat pipe among the plurality of heat pipes.
2. The heat transport apparatus according to claim 1, wherein one
end of the heat transport path is thermally connected to a
temperature adjusting mechanism, and types and/or numbers of the
heat pipes are selected in such a manner that a heat transport
capability at the one end is greater than a heat transport
capability at another end.
3. The heat transport apparatus according to claim 1, further
comprising a heater thermally connected to at least one of the
plurality of heat pipes.
4. The heat transport apparatus according to claim 1, wherein a
part of or an entirety of the heat transport path is accommodated
in an accommodating member that is thermally connectable to the
plurality of heat pipes and the object to be temperature
adjusted.
5. The heat transport apparatus according to claim 1, wherein a
working fluid of at least one heat pipe among the plurality of heat
pipes has a melting point different from a melting point of that of
the other heat pipe.
6. The heat transport apparatus according to claim 1, wherein
neighboring heat pipes are thermally connected by thermally
connecting end portion side surfaces thereof with each other.
7. The heat transport apparatus according to claim 1, wherein
neighboring heat pipes are thermally connected by thermally
connecting tip end surfaces thereof with each other.
8. The heat transport apparatus according to claim 1, wherein the
object to be temperature adjusted represents a plurality of objects
to be temperature adjusted.
9. The heat transport apparatus according to claim 8, wherein the
plurality of objects to be temperature adjusted are a plurality of
battery cells.
10. A heat transport apparatus that is thermally connectable to an
object to be temperature adjusted, comprising: a plurality of heat
pipes thermally connected along a heat transport direction to form
a heat transport path, each of the plurality of heat pipes
comprising a working fluid, the heat transport apparatus being
adapted to be used under an environment at or below a melting point
of the working fluid of at least one heat pipe among the plurality
of heat pipes, the heat transport apparatus having a first end and
a second end, the first end of the heat transport apparatus being
defined at least in part by a first one of the plurality of heat
pipes, the second end of the heat transport apparatus being defined
by at least a second one of the plurality of heat pipes, the first
end of the heat transport apparatus being adapted to be in heat
transfer communication with a temperature adjusting source, the
plurality of heat pipes being configured and arranged in such a
manner that a heat transport capability at one of the first and
second ends is greater than a heat transport capability at the
other of the first and second ends, the first one of the plurality
of heat pipes being of a first length, the second one of the
plurality of heat pipes being of a second length, the first length
being different from the second length.
11. The heat transport apparatus according to claim 10, wherein the
plurality of heat pipes is configured and arranged in such a manner
that the heat transport capability at the first end is greater than
the heat transport capability at the second end, and wherein the
first length is smaller than the second length.
12. The heat transport apparatus according to claim 11, further
comprising a heater in heat transfer communication with at least
the second one of the plurality of heat pipes, the heater
constituting the temperature adjusting source.
13. The heat transport apparatus according to claim 10, further
comprising a heater thermally connected to at least one of the
plurality of heat pipes.
14. The heat transport apparatus according to claim 10, wherein a
part of or an entirety of the heat transport path is accommodated
in an accommodating member that is thermally connectable to the
plurality of heat pipes and the object to be temperature
adjusted.
15. The heat transport apparatus according to claim 10, wherein the
working fluid of at least one heat pipe among the plurality of heat
pipes has a melting point different from a melting point of that of
the other heat pipe.
16. The heat transport apparatus according to claim 10, wherein
neighboring heat pipes are thermally connected by thermally
connecting end portion side surfaces thereof with each other.
17. The heat transport apparatus according to claim 10, wherein
neighboring heat pipes are thermally connected by thermally
connecting tip end surfaces thereof with each other.
18. The heat transport apparatus according to claim 10, wherein the
object to be temperature adjusted represents a plurality of objects
to be temperature adjusted.
19. The heat transport apparatus according to claim 16, wherein the
plurality of objects to be temperature adjusted are a plurality of
battery cells.
Description
TECHNICAL FIELD
[0001] The present disclosure relates to a heat transport
apparatus, and particularly to a heat transport apparatus having a
heat pipe as a heat transport unit.
BACKGROUND ART
[0002] Heat pipes are used as heat transport units in cooling or
heating various electronic components. For example, Patent Document
1 discloses providing a heat pipe, as a heat transport unit,
between a heater element and a radiation fin.
[0003] It is also known to thermally connect a plurality of heat
pipes along a heat transport direction. For example, Patent
Document 2 discloses connecting a plurality of flat plate heat
pipes, each not exceeding a critical length at which a heat
transport performance extremely decreases, to each other using a
means having a reduced junction thermal resistance to thereby
obtain a connection structure having a total overall length with
which a desired length is obtained.
[0004] Patent Document 3 discloses a connection type heat pipe in
which a plurality of heat pipe units each having a reducing section
formed at one end thereof and a nozzle portion for injecting a
working fluid continuously formed at a tip of the reducing section
are alternately and continuously connected to each other with their
corresponding end portions being joined in a closely attached
manner at the flat portion.
[0005] However, none of the aforementioned documents disclose using
heat pipes in an environment at or below a temperature of a melting
point of the working fluid.
[0006] Techniques that takes into consideration the lowering of
heat transport efficiency due to freezing of a working fluid are
disclosed in Patent Documents 4 and 5. With the inventions
described in these documents, condensing capability of some of the
heat pipes is decreased by connecting less number of fins to some
of the heat pipes than to other heat pipes, to thereby cause the
some of the heat pipes to positively operate under a low
temperature.
DOCUMENT LIST
Patent Document(s)
[0007] Patent Document 1: Japanese Laid-Open Patent Publication No.
2006-310739
[0008] Patent Document 2: Japanese Patent No. 4069302
[0009] Patent Document 3: Japanese Laid-Open Utility-Model
Publication No. S61-84382
[0010] Patent Document 4: Japanese Laid-Open Patent Publication No.
2001-267773
[0011] Patent Document 5: Japanese Laid-Open Patent Publication No.
H07-190655
SUMMARY OF INVENTION
Technical Problem
[0012] It is an object of the present disclosure to provide a heat
transport apparatus that includes heat pipes as a heat transport
unit and that can suppress the lowering of heat transport
efficiency due to freezing of the working fluid as much as possible
even under a low temperature condition at or below a melting point
of the working fluid.
Solution to Problem
[0013] In order to achieve the above object, the present disclosure
adopted the following configuration.
[0014] That is, according to a first aspect of the present
disclosure, a heat transport apparatus that is thermally
connectable to an object to be temperature adjusted includes a
plurality of heat pipes thermally connected along a heat transport
direction to form a heat transport path. It is preferable that the
heat transport apparatus is used under an environment at or below a
melting point of a working fluid of at least one heat pipe among
the plurality of heat pipes.
[0015] According to a second aspect of the present disclosure, one
end of the heat transport path is thermally connected to a
temperature adjusting mechanism, and types and/or numbers of the
heat pipes are selected in such a manner that a heat transport
capability at the one end is greater than a heat transport
capability at another end.
[0016] According to a third aspect of the present disclosure, the
heat transport apparatus further includes a heater thermally
connected to at least one of the plurality of heat pipes.
[0017] According to a fourth aspect of the present disclosure, a
part of or an entirety of the heat transport path is accommodated
in an accommodating member that is thermally connectable to the
plurality of heat pipes and the object to be temperature
adjusted.
[0018] According to a fifth aspect of the present disclosure, a
working fluid of at least one heat pipe among the plurality of heat
pipes has a melting point different from a melting point of that of
the other heat pipe.
[0019] According to a sixth aspect of the present disclosure,
neighboring heat pipes are thermally connected by thermally
connecting end portion side surfaces thereof with each other.
[0020] According to a seventh aspect of the present disclosure,
neighboring heat pipes are thermally connected by thermally
connecting tip end surfaces thereof with each other.
[0021] According to an eighth aspect of the present disclosure, the
object to be temperature adjusted represents a plurality of objects
to be temperature adjusted.
[0022] According to a ninth aspect of the present disclosure, the
plurality of objects to be temperature adjusted are a plurality of
battery cells.
Advantageous Effects of Invention
[0023] According to the present disclosure, since a plurality of
heat pipes are thermally connected along a heat transport direction
to form a heat transport path, a decrease in the heat transport
efficiency due to freezing of a working fluid can be suppressed as
much as possible even in a low temperature condition of at or below
a melting point of the working fluid.
BRIEF DESCRIPTION OF DRAWINGS
[0024] FIG. 1 is a perspective view showing a heat transport
apparatus of the present disclosure in a state where it is
thermally connected to a group of battery cells that is an object
to be temperature adjusted.
[0025] FIG. 2 is an exploded perspective view showing the heat
transport apparatus of FIG. 1.
[0026] FIG. 3 is a top plan view showing an arrangement of heat
pipes in the heat transport apparatus of FIG. 1.
[0027] FIGS. 4A and 4B are perspective views showing a connecting
portion of the heat pipes in the heat transport apparatus of FIG.
1.
[0028] FIGS. 5A and 5B are perspective views showing another
configuration of the connecting portion of the heat pipes.
[0029] FIGS. 6A and 6B are perspective views showing another
configuration of the connecting portions of the heat pipes.
[0030] FIG. 7 is a top plan view showing another configuration of
the arrangement of the heat pipes in the heat transport
apparatus.
[0031] FIG. 8 is a top plan view showing another configuration of
the arrangement of the heat pipes in the heat transport
apparatus.
[0032] FIG. 9 is a perspective view showing the heat transport
apparatus of the present disclosure in a state where the heat
transport apparatus is thermally connected to a group of battery
cells (battery component) that is an object to be temperature
adjusted.
[0033] FIG. 10 is an exploded perspective view showing the heat
transport apparatus of FIG. 9.
[0034] FIG. 11 is a cross sectional view of the heat transport
apparatus of FIG. 9.
[0035] FIG. 12 is a perspective view showing the heat transport
apparatus of the present disclosure in a state where the heat
transport apparatus is thermally connected to a group of battery
cells (battery components) that are an object to be temperature
adjusted.
[0036] FIG. 13 is an exploded perspective view showing the heat
transport apparatus of FIG. 13.
[0037] FIG. 14 is a perspective view showing a battery temperature
adjustment apparatus provided with the heat transport apparatus of
the present disclosure.
[0038] FIG. 15 is a top plan view of the apparatus of FIG. 14.
[0039] FIG. 16 is an exploded perspective view showing a cooling
unit 30.
[0040] FIG. 17 is a cross sectional view showing a cooling unit
30.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0041] Hereinafter, embodiments of the present disclosure will be
described in detail.
Embodiment 1
[0042] FIG. 1 is a perspective view showing a heat transport
apparatus of the present disclosure in a state where the heat
transport apparatus is thermally connected to a group of battery
cells 20 including a plurality of battery cells 21 as an object to
be temperature adjusted. FIG. 2 is an exploded perspective view
showing the heat transport apparatus of FIG. 1. FIG. 3 is a top
plan view showing one mode of arrangement of heat pipes in the heat
transport apparatus of FIG. 1. FIGS. 4A and 4B are perspective
views showing a connecting portion between the heat pipes in the
heat transport apparatus of FIG. 1.
[0043] The heat transport apparatus 10 includes groups 1a to 1g of
a plurality of heat pipes 3 that are arranged in parallel and each
having a substantially rectangular cross section. The groups 1a to
1g each includes a plurality of heat pipes 3 (in this embodiment,
seven heat pipes) arranged in parallel. An end portion of the group
1a and an end portion of the group 1b are thermally connected.
[0044] Similarly, the group 1b and the group 1c are thermally
connected; the group 1c and the group 1d are thermally connected;
the group 1d and the group 1e are thermally connected; the group 1e
and the group 1f are thermally connected; and the group lf and the
group 1g are thermally connected.
[0045] In such a manner, a heat transport path extends along a heat
transport direction A by thermally connecting the end portions of
the heat pipes 3 in turn. In this embodiment, the heat pipes 3
constituting to the groups 1a to 1g have the same shape and the
same working fluid, respectively. However, those of different
shapes and different working fluids may of course be used.
[0046] A method of connecting the heat pipes 3 in the heat
transport direction will be described. As shown in FIGS. 4A and 4B,
in this embodiment, an end portion side surface of the heat pipe 3a
and an end portion side surface of the heat pipe 3b are thermally
connected; an end portion side surface of the heat pipe 3b and an
end portion side surface of the heat pipe 3c are thermally
connected; an end portion side surface of the heat pipe 3c and an
end portion side surface of the heat pipe 3d are thermally
connected; an end portion side surface of the heat pipe 3d and an
end portion side surface of the heat pipe 3e are thermally
connected; an end portion side surface of the heat pipe 3e and an
end portion side surface of the heat pipe 3f are thermally
connected; and an end portion side surface of the heat pipe 3f and
an end portion side surface of the heat pipe 3g are thermally
connected. Thereby, a total of seven heat pipes 3a to 3g are
thermally connected along a heat transport direction A. The method
of connecting the heat pipes 3 is not limited to connection between
end portions of narrow-width surfaces as shown in FIGS. 4A and 4B,
and end portions of wide-width surfaces may be connected as shown
in FIGS. 5A and 5B. Also, as shown in FIGS. 6A and 6B, a thermal
resistance member 5 may be provided at a part of the connecting
portion to adjust a heat transport rate of a part of the heat
transport path. The thermal resistance member may be a thermal
sheet, solder, a metal plate, or the like, that can adjust a
thermal resistance value and a thermal conductivity by physical
properties, shape or the like thereof, such as thickness and
specific heat.
[0047] The aforementioned heat pipe 3 includes, for example, a
sealed container made of a metal having a good thermal
conductivity, such as copper and aluminum, or an alloy of such a
metal, and a working fluid enclosed in the sealed container in a
depressurized state. The shape of the container may be, in addition
to a shape having a substantially rectangular cross section of the
present embodiment, a shape having a flattened cross section, a
round shape, a plate shape, or the like. The heat pipe may be of a
type having a wick formed on an inner surface of the container with
a mesh or a coil of a metal wire or a porous metal, and of a type
having grooves formed on an inner surface of the container. A space
serving as a channel for the working fluid is also provided inside
the heat pipe 3. Heat transportation is performed by a phase change
between evaporation (heat receiving section) and condensation (heat
radiating section) and an internal movement of the working fluid
contained in this space. The working fluid includes, but not
limited to, water, hydrochlorofluoro carbons such as HCFC-22,
hydrofluorocarbons such as HFCR134a, HFCR407C, HFCR410A and HFC32,
hydrofluoroolefins such as HFO1234yf, carbon dioxide gas, ammonia
and propane. Among these, taking the performance and influences on
global environment into consideration, water, carbon dioxide gas,
and hydrofluoroolefin are preferable.
[0048] A total of 49 heat pipes 3 constituting the groups 1a to 1g
are accommodated in an accommodating member 2. The accommodating
member 2 includes an accommodating container 2a and a flat plate
cover 2b, and is thermally connected to the group of battery cells
20 and the heat pipes 3. Although a material of the accommodating
member 2 is not particularly limited, considering a good thermal
conductivity, it is preferable to use a metal such as copper and
aluminum at least at a connecting portion between an object to be
temperature adjusted and a temperature adjusting mechanism.
Further, in this embodiment, a sheet 30 having a good thermal
conductivity is disposed between the group of battery cells 20 and
the accommodating member 2. A material of such a sheet 30 is not
particularly limited, and may be a so-called thermal sheet,
thermally conductive grease and a putty containing silicone or
acrylic rubber as a major component. Also, a temperature adjusting
mechanism 40 (in this embodiment, a heater) is thermally connected
to an end portion of the cover 2b.
[0049] Hereinafter, an operation of the aforementioned heat
transport apparatus 10 will be described for a case in which water
is used as a working fluid. It is known that a battery 21 such as a
lithium ion secondary battery has an appropriate operating
temperature range and an output decreases under a low temperature
condition (e.g., 0.degree. C. and below). Therefore, in order to
carry out an appropriate operation under such a condition, it is
necessary to preheat the battery to increase the temperature to an
appropriate operating temperature. Since the heat transport
apparatus 10 has a heat transport path provided by the heat pipes
3, heat from the heater 40 can be efficiently transported to the
battery cells 21.
[0050] Also, when a long heat transport path (e.g., a heat
transport path having a length which is greater than 50 cm, and
particularly, greater than or equal to 60 cm (an upper limit is
preferably less than or equal to 2 m)) is constituted by a single
long heat pipe, there is a drawback that the heat transport
efficiency decreases due to freezing of the working fluid in the
heat pipe. In other words, even though the working fluid melted by
heat from the heater 40 turns into vapor in the vicinity of the
heater 40 (heat generation section) and the vapor moves inside the
heat pipe towards a low temperature section, the vapor is cooled at
the low temperature section and freezes. Accordingly, there is a
drawback that the working fluid does not circulate towards the heat
generation section and will be depleted in the vicinity of the heat
generation section.
[0051] According to the present disclosure, since a plurality of
(in this embodiment, a total of seven) heat pipes 3 are thermally
connected along the heat transport direction A, a decrease in the
heat transport efficiency due to the freezing of the heat pipe can
be prevented as compared to a case in which heat is transported
using a single long heat pipe. That is, in a case of a short heat
pipe, even in a situation where the working fluid might freeze,
since heat conduction takes place in the container and at the wick
portion, the freezing of the working fluid can be prevented by the
heating. Also, since a plurality of short heat pipes are thermally
connected, heat pipes that are far from the heat source can be
operated and heat can be transported over a long-distance. In
addition to a heat pipe that is not frozen, such an effect is also
effective to a heat transport path that is already frozen. Since
short heat pipes restore their function by being thawed by heat
conduction through the container and the wick portion, heat can be
transferred well to the next heat pipe in the heat transport
direction. Since the function of the heat pipe recovers in turn, a
good heat transport is finally restored in the entire path. Taking
such a freezing problem into consideration, the heat pipe 3 has a
length of preferably less than or equal to 50 cm, particularly
preferably less than or equal to 40 cm, and further preferably less
than or equal to 30 cm.
[0052] Further, as a temperature adjusting mechanism, a cooling
mechanism may be connected to the heat transport apparatus in
addition to the heater 40, and when the battery is overheated, the
heat of the battery can be efficiently transported to the cooling
mechanism by the heat pipe 3. Such a cooling mechanism may be
formed integral with the heater 40 or may be formed separately and
connected to the heater 40.
[0053] In the embodiment above, the groups (1a to 1g) each
including seven heat pipes are arranged, but it is not limited to
such an arrangement, and various arrangements are possible. Also,
the plurality of heat pipes 3 need not be necessarily identical,
and those having different shapes (lengths, diameters) or different
working fluids may be used in combination.
[0054] For example, in the embodiment shown in FIG. 7, the heat
pipes 3 are disposed in such a manner that a number of heat pipes
3a constituting one end of the heat transport path is maximum, and
a density of the heat pipes 3d constituting the other end of the
heat transport path is minimum. At an intermediate portion (between
the one end and the other end) of the heat transport path, the
number of heat pipes does not increase from one end to the other
end of the heat transport path (a heat transport capability does
not increase) except at junction portions of the heat pipes. In
such an embodiment, it is preferable to thermally connect a side at
which the heat pipe density is high (the 3a side) to the
temperature adjusting mechanism such as the cooling mechanism.
Thereby, it is possible to sufficiently deal with an amount of heat
transport that increases towards the cooling mechanism side.
[0055] Further, in the embodiment shown in FIG. 8, a length of the
heat pipes 3e constituting one end of the heat transport path is
the greatest, and a length of the heat pipes 3a constituting the
other end of the heat transport path is the shortest. In such an
embodiment, it is preferable to connect the short heat pipe side
(the other end, the 3a side) to the temperature adjusting mechanism
such as the cooling mechanism. Since the heat pipe has a higher
heat transport capability as the length becomes shorter, it is also
possible to sufficiently deal with an amount of heat transport that
increases towards the cooling mechanism side.
[0056] Furthermore, in the aforementioned embodiment, an embodiment
using the heater as the temperature adjusting mechanism 40 was
described. However, the heater need not be necessarily connected to
the heat transport apparatus, and, for example, it may be
configured to drive only a part of the battery cells that are
connected to the heat transport apparatus 10, and to heat other
battery cells connected to the heat transport apparatus with the
generated heat.
[0057] In such an embodiment, although it is not necessarily
required to connect the temperature adjusting mechanism 40, the
temperature adjusting mechanism 40 as the cooling mechanism may be
connected to the heat transport apparatus 10. Also, by providing
the aforementioned thermal resistance member at a connecting
portion of the heat pipes 3 near the cooling mechanism (e.g., a
connecting portion between the heat pipes 3a and 3b in FIG. 2), a
heat loss produced due to transportation of heat to the cooling
mechanism during the heating of the battery cells 21 can be
suppressed.
[0058] Note that, the aforementioned heater includes, but not
particularly limited to, an electric heater, Peltier element, and
the like, and the cooling mechanism may be a fin, a water-cooled
mechanism, a heat pump, and the like. Further, in the above
embodiment, a case in which the working fluids of the heat pipes 3
were assumed to be the same was described, but the heat pipes
having different working fluids may be used in combination.
Further, instead of connecting the end portion side surfaces, the
heat pipes may be connected by connecting the tip end surfaces to
each other. The object to be temperature adjusted is not limited to
battery cells, and the heat transport apparatus of the present
disclosure is applicable to any machines, appliances and devices
that require cooling and/or heating. It is particularly preferable
for temperature adjustment of machines, appliances and devices,
such as automotive batteries for cold places, which are assumed to
be used at an operating temperature of less than or equal to
0.degree. C.
Embodiment 2
[0059] Another embodiment of the present disclosure will be
described below. FIG. 9 is a perspective view showing the heat
transport apparatus of the present disclosure in a state where the
heat transport apparatus is thermally connected to a battery
component 20A comprising a group of battery cells 21 that is an
object to be temperature adjusted. FIG. 10 is an exploded
perspective view showing the heat transport apparatus of FIG. 9.
FIG. 11 is a cross sectional view of the heat transport apparatus
of FIG. 9.
[0060] In this embodiment, the heat transport apparatus is disposed
between the battery components 20A each including a plurality of
batteries arranged therein. It is to be noted that the battery
component 20A may include a single battery cell.
[0061] The heat transport apparatus 10' includes groups 11a to 11c
each including a plurality of heat pipes 3 that are arranged in
parallel and each having a substantially rectangular cross section
as well as a heat pipe 3 (11d) disposed at an end portion.
[0062] Similarly to Embodiment 1, a heat transport path extends
along the heat transport direction A by thermally connecting the
end portions of the heat pipes 3 in turn. In this embodiment, the
heat pipes 3 constituting groups 1a to 1d have the same shape and
the same working fluid, respectively. However, those of different
shapes and different working fluids may of course be used.
[0063] The heat pipes 3 are connected with each other in a manner
similar to the configuration of FIGS. 4A and 4B, and may also be,
similarly to Embodiment 1, connected in a manner of the
configuration as shown in FIGS. 5A and 5B or FIGS. 6A and 6B. The
heat pipes 3 of various structures described in Embodiment 1 can be
used.
[0064] A total of seven heat pipes 3 constituting the groups 11a to
11d are accommodated in the accommodating member 2. The
accommodating member 2 includes two plates 2c each having a flat
plate shape, and is thermally connected to the battery cells 21 and
the heat pipes 3. Although the material of the accommodating member
2 is not particularly limited, considering a good thermal
conductivity, it is preferable to use a metal such as copper and
aluminum at a connecting portion between at least an object to be
temperature adjusted and a temperature adjusting mechanism.
[0065] A temperature adjusting mechanism 40 is thermally connected
to an end portion of the plate 2c. The temperature adjusting
mechanism 40 is, in this embodiment, a heater (specifically, a PTC
heater) 12. In this embodiment, when a sheet-like PTC heater is
used, since the temperature adjusting mechanism 40 can be
accommodated between the plates 2c, a temperature controller can be
dispensed with and a size of an entire apparatus can be
minimized.
[0066] Hereinafter, an operation of the aforementioned heat
transport apparatus 10' will be described for a case in which water
is used as a working fluid. It is known that a battery such as a
lithium ion secondary battery has an appropriate operating
temperature range and an output decreases under a low temperature
condition (e.g., 0.degree. C. or below). Therefore, in order to
carry out an appropriate operation under such a condition, it is
necessary to preheat the battery to increase the temperature to an
appropriate operating temperature. Since the heat transport
apparatus 10' has a heat transport path formed with the heat pipes
3, heat from the heater 40 can be efficiently transported to the
battery cells 21. Although the heater 40 is provided in this
embodiment, it is to be noted that, for example, similarly to
Embodiment 1, some of the battery cells among the battery cells
connected to the heat transport apparatus 10 may be driven and
generate heat, and other battery cells connected to the heat
transport apparatus may be heated by the heat thus generated.
[0067] Also, when a long heat transport path (e.g., a heat
transport path having a length which is greater than 50 cm, and
particularly, greater than or equal to 60 cm (an upper limit is
preferably less than or equal to 2 m)) is constituted by a single
long heat pipe, there is a drawback that the heat transport
efficiency decreases due to freezing of the working fluid in the
heat pipe. In other words, even though the working fluid melted by
the heat from the heater 12 turns into vapor in the vicinity of the
heater 12 (heat generation section) and the vapor moves inside the
heat pipe towards a low temperature section, the vapor is cooled at
the low temperature section and freezes. Accordingly, there is a
drawback that the working fluid does not circulate towards the heat
generation section and will be depleted in the vicinity of the heat
generation section.
[0068] According to the present disclosure, since a plurality of
(in this embodiment, a total of four) heat pipes 3 are thermally
connected along the heat transport direction A, a decrease in the
heat transport efficiency due to the freezing of the heat pipe can
be prevented as compared to a case in which heat is transported
using a single long heat pipe. That is, in a case of a short heat
pipe, even in a situation where the working fluid might freeze,
since heat conduction takes place in the container and at the wick
portion, the freezing of the working fluid can be prevented by the
heating. Also, since a plurality of short heat pipes are thermally
connected, heat pipes that are far from the heat source can be
operated and heat can be transported over a long-distance. In
addition to a heat pipe that is not frozen, such an effect is also
effective to a heat transport path that is already frozen. Since
short heat pipes are thawed by heat conduction of the container and
the wick portion and restore the function, heat can be transferred
well to the next heat pipe in the heat transport direction. Since
the function of the heat pipe recovers in turn, a good heat
transport is finally restored in the entire path. Taking such a
freezing problem into consideration, the heat pipe 3 has a length
of preferably less than or equal to 50 cm, particularly preferably
less than or equal to 40 cm, and further preferably less than or
equal to 30 cm.
[0069] Further, as a temperature adjusting mechanism, a cooling
mechanism (in the present embodiment, water cooling jackets 14a,
14b as a part of the water cooling mechanism) may be connected to
the heat transport apparatus in addition to the heater 40, and when
the battery is overheated, the heat of the battery can be
efficiently transported to the cooling mechanism by the heat pipe
3. Further, in the present embodiment, the heat pipes 3 are
disposed in such a manner that number of heat pipes 3 of the group
of heat pipes 11a constituting one end of the heat transport path
is maximum (heat transport capability at one end of the heat
transport path is maximum), and, a density of the heat pipes 3 of
the group of heat pipes 11d constituting the other end of the heat
transport path is minimum (heat transport capability at the other
end of the heat transport path is minimum). At an intermediate
portion (between the one end and the other end) of the heat
transport path, the number of heat pipes does not increase from one
end to the other end of the heat transport path (a heat transport
capability does not increase) except at junction portions of the
heat pipes. Thereby, it is possible to sufficiently deal with an
amount of heat transport that increases towards the cooling
mechanism side. Also, by providing the aforementioned thermal
resistance member at a connecting portion of the heat pipes 3 which
is near the cooling mechanism (e.g., a connecting portion between
the heat pipes 3 constituting the group of heat pipes 11a and the
heat pipes 3 constituting the group 11b in FIG. 10), a heat loss
produced due to transportation of heat to the cooling mechanism
during the heating of the battery cells 21 can be suppressed.
[0070] In the embodiment above, the groups (11a to 11d) each
comprising two or one heat pipes/pipe are/is arranged, but it is
not limited to such an arrangement, and various arrangements are
possible. Also, the plurality of heat pipes 3 need not be
necessarily identical, and those having different shapes (lengths,
diameters) and different working fluids may be used in combination.
Also, in the present embodiment, too, as shown in FIG. 8, the heat
pipes of different length may be used, and a heat transport
capability on the cooling mechanism side may be maximized by
minimizing the length of the heat pipes 3 (11a) constituting one
end of the heat transport path and maximizing the length of the
heat pipes 3 (11d) constituting the other end of the heat transport
path.
[0071] The heater described above may be, but not particularly
limited to, an electric heater, a Peltier element, or the like, and
the cooling mechanism may be a fin, a water-cooled mechanism, a
heat pump or the like. In the aforementioned embodiment, a case in
which the working fluids of the heat pipes 3 are the same was
described. However, a combination of heat pipes of different
working fluids may be used. Further, the heat pipes may be
connected at tip end surfaces instead of being connected at end
portion side surfaces. An object to be temperature adjusted is not
limited to battery cells, and the heat transport apparatus of the
present disclosure is applicable to various machines, appliances
and devices requiring cooling and/or heating. Particularly, it is
preferable for machines, appliances and devices having cold weather
specification that assumes that an operating temperature may be
0.degree. C. or below.
Embodiment 3
[0072] Next, an embodiment in which battery cells of other
geometries are used instead of the aforementioned prismatic battery
cells will be described with reference to FIGS. 12 and 13. FIG. 12
is a perspective view showing a state in which the heat transport
apparatus 50 of the present disclosure is disposed between
cylindrical battery cells 20. FIG. 13 is an exploded perspective
view showing the heat transport apparatus 50 of FIG. 13. In FIGS.
12 and 13, members which are the same as those of the heat
transport apparatus 10 are indicated with common reference
numerals.
[0073] A securing section 53 of the heat transport apparatus 50 is
provided with a heat pipe accommodating hole 57 and a heater
accommodating hole 58 in which the heat pipes 11 and the heater 12
are accommodated, respectively. On each side surface of the
fastening unit 53, concaved portions 55 each formed to match an
outer peripheral shape of the battery cell 20 and a pair of latches
56a and 56b are formed. The battery cell 21 is retained in a state
where it is fitted within the concaved portion 55 by the pair of
latches 56a and 56b.
[0074] Similarly to the case of the heat transport apparatus 10' of
Embodiment 2, jackets 14a and 14b are connected to an end portion
of the securing section 53.
Embodiment 4
[0075] Another embodiment of a battery temperature adjustment
apparatus comprising the heat transport apparatus of the present
disclosure will now be described. A battery temperature adjustment
apparatus 100 includes the heat transport apparatus 10' described
in the aforementioned Embodiment 2. FIG. 14 is a perspective view
showing the battery temperature adjustment apparatus 100. FIG. 15
is a top plan view thereof.
[0076] The battery temperature adjustment apparatus 100 includes
the heat transport apparatus 10' of the present disclosure and a
battery cooling unit 30. It is to be noted that the heat transport
apparatus 10' includes the water-cooled jacket 14, and the heat
pipe 11 is thermally connected to a cooling unit (water-cooled
unit). The configuration of the battery cooling unit 30 is similar
to the configuration of the heat transport apparatus 10' except
that it is not provided with a heater and provided with two long
heat pipes 31 as the heat pipes (see FIGS. 16 and 17).
[0077] In the battery temperature adjustment apparatus 100, the
heat transport apparatus 10' and the battery cooling unit 30 are
alternately disposed in a gap of battery component 20A. That is,
the heat pipe 31 of the battery cooling unit 30 is thermally
connected to a surface on the other side of the surface thermally
connected to the heat transport apparatus 10' of the battery cell
20.
[0078] With an analysis by the present inventors, it is found that
it is effective to perform cooling from both sides of the battery
cell and it is sufficient to perform heating of the battery cell
from one side. Accordingly, by using the battery temperature
adjustment apparatus 100, the heating and the cooling of the
battery can be performed efficiently and the weight of the
apparatus can be decreased.
[0079] Note that, in the aforementioned battery temperature
adjustment apparatus 100, the heat transport apparatus 10' and the
battery cooling unit 30 are provided with the water-cooling jacket,
but by connecting a fin instead of the water-cooling jacket, the
configuration may be such that the heat pipe 11 and the heat pipe
31 are connected to the cooling unit (an external atmosphere or an
air conditioning system). Although the water-cooling jacket or the
fin can be provided one each for the heat transport apparatus 10'
and 30, a plurality of units may share a single water-cooling
jacket or a fin.
List of Reference Signs
[0080] 1a to 1g group of heat pipes
[0081] 2 accommodating member
[0082] 3 heat pipe
[0083] 10 heat transport apparatus
[0084] 20 group of battery cells
[0085] 21 battery cell
[0086] 30 sheet
[0087] 40 temperature adjusting mechanism
[0088] 5 thermal resistance member
* * * * *