U.S. patent application number 13/730360 was filed with the patent office on 2013-10-03 for magnetic refrigeration device and magnetic refrigeration system.
The applicant listed for this patent is Toshiro HIRAOKA, Shiori KAJI, Tadahiko KOBAYASHI, Akiko SAITO, Yasushi SANADA, Norihiro TOMIMATSU, Ryosuke YAGI. Invention is credited to Toshiro HIRAOKA, Shiori KAJI, Tadahiko KOBAYASHI, Akiko SAITO, Yasushi SANADA, Norihiro TOMIMATSU, Ryosuke YAGI.
Application Number | 20130255279 13/730360 |
Document ID | / |
Family ID | 47522413 |
Filed Date | 2013-10-03 |
United States Patent
Application |
20130255279 |
Kind Code |
A1 |
TOMIMATSU; Norihiro ; et
al. |
October 3, 2013 |
MAGNETIC REFRIGERATION DEVICE AND MAGNETIC REFRIGERATION SYSTEM
Abstract
In a magnetic refrigeration device, magnetic bodies having a
magnetocaloric effect and solid heat accumulation members having
heat accumulation effect are arranged alternately with gaps
therebetween. Magnetic field apply units start and stop application
of magnetic fields to the magnetic bodies. A contact mechanism
brings each of the magnetic bodies into contact with one of the
solid heat accumulation members adjacent to the each magnetic body.
Alternatively, the contact mechanism brings each of the solid heat
accumulation members into contact with one of the magnetic bodies
adjacent to the each solid heat accumulation members.
Inventors: |
TOMIMATSU; Norihiro;
(Mitaka-shi, JP) ; HIRAOKA; Toshiro;
(Yokohama-shi, JP) ; SANADA; Yasushi;
(Yokohama-shi, JP) ; YAGI; Ryosuke; (Yokohama-shi,
JP) ; SAITO; Akiko; (Kawasaki-shi, JP) ;
KOBAYASHI; Tadahiko; (Yokohama-shi, JP) ; KAJI;
Shiori; (Kawasaki-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TOMIMATSU; Norihiro
HIRAOKA; Toshiro
SANADA; Yasushi
YAGI; Ryosuke
SAITO; Akiko
KOBAYASHI; Tadahiko
KAJI; Shiori |
Mitaka-shi
Yokohama-shi
Yokohama-shi
Yokohama-shi
Kawasaki-shi
Yokohama-shi
Kawasaki-shi |
|
JP
JP
JP
JP
JP
JP
JP |
|
|
Family ID: |
47522413 |
Appl. No.: |
13/730360 |
Filed: |
December 28, 2012 |
Current U.S.
Class: |
62/3.1 |
Current CPC
Class: |
F25B 21/00 20130101;
F25B 2321/0022 20130101; Y02B 30/66 20130101; Y02B 30/00 20130101;
F25B 2321/002 20130101 |
Class at
Publication: |
62/3.1 |
International
Class: |
F25B 21/00 20060101
F25B021/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 29, 2012 |
JP |
2012-076718 |
Claims
1. A magnetic refrigeration device comprising: a plurality of
stationary members arranged in parallel with each other, with gaps
defined between adjacent ones of the stationary members, each of
the stationary members being formed of one of a magnetic body
having a magnetocaloric effect, and a solid heat accumulation
member having a heat accumulation effect, the adjacent ones of the
stationary members opposing each other; a plurality of movable
members arranged in parallel with each other, and permitted to be
brought into contact with the adjacent stationary members within
the respective gaps and thermally connected to the adjacent
stationary members, each of the movable members being formed of the
other of the magnetic body and the solid heat accumulation member;
a magnetic field apply unit configured to start and stop
application of a magnetic field to the magnetic body; and a moving
mechanism configured to selectively bring the movable members to
the corresponding stationary members in synchronism with the start
and stop of the application of the magnetic field of the magnetic
field apply unit.
2. The device according to claim 1, wherein the moving mechanism
comprises a driving unit configured to drive the movable members
using an external magnetic attraction force.
3. The device according to claim 1, wherein the moving mechanism
comprises a driving unit configured to drive the movable members
using an electrostatic force.
4. The device according to claim 3, wherein an insulating layer is
formed on at least one of the stationary member and the movable
member opposing each other with the corresponding gap.
5. The device according to claim 1, further comprising sealing
means for maintaining each of the gaps at a reduced pressure.
6. A magnetic refrigeration system comprising the magnetic
refrigeration device recited in claim 1.
7. A magnetic refrigeration system comprising a plurality of
magnetic refrigeration devices arranged substantially along a
circle and each including: a stationary members arranged in
parallel with each other, with gaps defined between adjacent ones
of the stationary members, each of the stationary members being
formed of one of a magnetic body having a magnetocaloric effect,
and a solid heat accumulation member having a heat accumulation
effect, the adjacent ones of the stationary members opposing each
other; and a plurality of movable members arranged in parallel with
each other, and permitted to be brought into contact with the
adjacent stationary members within the respective gaps and
thermally connected to the adjacent stationary members, each of the
movable members being formed of the other of the magnetic body and
the solid heat accumulation member; at least one magnetic field
apply unit provided along the circle over or below the plurality of
magnetic refrigeration devices and configured to start and stop
application of a magnetic field to the magnetic body; and a moving
mechanism configured to selectively bring the movable members to
the corresponding stationary members in synchronism with the start
and stop of the application of the magnetic field of the magnetic
field apply unit.
8. The system according to claim 7, wherein the plurality of
magnetic refrigeration devices are thermally connected to each
other in series or in parallel.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based upon and claims the benefit of
priority from Japanese Patent Application No. 2012-076718, filed
Mar. 29, 2012, the entire contents of which are incorporated herein
by reference.
FIELD
[0002] Embodiments described herein relate generally to magnetic
refrigeration devices and magnetic refrigeration systems.
BACKGROUND
[0003] In recent years, there is an increasing demand for magnetic
refrigeration as one refrigeration technique of high refrigeration
efficiency, and research and development of magnetic, refrigeration
techniques targeted for room temperature have now been
intensified.
[0004] As one of the magnetic refrigeration techniques, active
magnetic refrigeration (AMR) system has been proposed. In the AMR
system, lattice entropy regarded as a disincentive for magnetic
refrigeration at room temperature is positively utilized, and both
a function of performing magnetic refrigeration and a function of
accumulating the cold energy generated by the magnetic
refrigeration are imparted to a magnetic substance,
[0005] Typical AMR apparatuses have a structure, in which a heat
exchange fluid, such as water, is made to flow in a magnetic
container filled with, for example, magnetic particles, and is
moved back and forth in synchronism with application/elimination of
a magnetic field to the magnetic container. As a result,
refrigeration cycle is realized.
[0006] In the AMR cycle, no compressors are needed and hence little
motive energy is required. Therefore, the AMR cycle is expected to
provide a higher refrigeration efficiency than conventional
refrigeration systems based a compression cycle using
chlorofluorocarbon.
[0007] However, to increase the rate of the magnetic refrigeration
cycle for downsizing the device or higher output, it is necessary
to make the heat exchange fluid flow in the magnetic container at
higher rate. This may involve, high fluid pressure loss, thereby
reducing the refrigeration efficiency.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a schematic cross-sectional view illustrating a
magnetic refrigeration device according to a first embodiment;
[0009] FIG. 2A is a schematic cross-sectional view illustrating
another magnetic substance with flexibility shown in FIG. 1;
[0010] FIG. 2B is a schematic cross-sectional view illustrating yet
another magnetic substance with flexibility shown in FIG. 1;
[0011] FIG. 2C is a schematic cross-sectional view illustrating a
further magnetic substance with flexibility shown in FIG. 1;
[0012] FIG. 3A is a schematic cross-sectional view explaining the
operation of the magnetic refrigeration device shown in FIG. 1;
[0013] FIG. 3B is another schematic cross-sectional view explaining
the operation of the magnetic refrigeration device shown in FIG.
1;
[0014] FIG. 4 is a schematic cross-sectional view explaining the
operation of a Magnetic refrigeration device according to a second
embodiment;
[0015] FIG. 5 is a schematic cross-sectional view illustrating a
unit structure of a magnetic refrigeration device according to a
third embodiment;
[0016] FIG. 6 is a schematic cross-sectional view illustrating a
magnetic refrigeration device according to a fourth embodiment;
[0017] FIG. 7 is a schematic cross-sectional view explaining the
operation of the magnetic refrigeration device shown in FIG. 6;
[0018] FIG. 8 is another schematic cross-sectional view explaining
the operation of the magnetic refrigeration device shown in FIG.
6;
[0019] FIG. 9 is a schematic cross-sectional view illustrating a
magnetic refrigeration device according to a modification of the
fourth embodiment;
[0020] FIG. 10A is a schematic cross-sectional view illustrating
the operation of a unit structure in a magnetic refrigeration
device according to another modification of the fourth
embodiment;
[0021] FIG. 10B is a schematic cross-sectional view illustrating
the operation of a unit structure in a magnetic refrigeration
device according to yet another modification of the fourth
embodiment;
[0022] FIG. 10C is a schematic cross-sectional view illustrating
the operation of a unit structure in a magnetic refrigeration
device according to a further another modification of the fourth
embodiment;
[0023] FIG. 11 is a schematic cross-sectional view illustrating a
magnetic refrigeration device according to a fifth embodiment;
[0024] FIG. 12 is a schematic perspective view illustrating a
magnetic refrigeration system according to a sixth embodiment;
[0025] FIG. 13 is a schematic plan view illustrating the
configuration of the elements of a magnetic refrigeration system
according to a seventh embodiment; and
[0026] FIG. 14 is a schematic plan view illustrating the
configuration of the elements of a magnetic refrigeration system
according to an eighth embodiment.
DETAILED DESCRIPTION
[0027] In general, according to an embodiment, there is provided a
magnetic refrigeration device comprising:
[0028] a plurality of stationary members arranged in parallel with
each other, with gaps defined between adjacent ones of the
stationary members, each of the stationary members being formed of
one of a magnetic body having a magnetocaloric effect, and a solid
heat accumulation member having a heat accumulation effect, the
adjacent ones of the stationary members opposing each other;
[0029] a plurality of movable members arranged in parallel with
each other, and permitted to be brought into contact with the
adjacent stationary members within the respective gaps and
thermally connected to the adjacent stationary members, each of the
movable members being formed of the other of the magnetic body and
the solid heat accumulation member;
[0030] a magnetic field apply unit configured to start and stop
application of a magnetic field to the magnetic body; and
[0031] a moving mechanism configured to selectively bring the
movable members to the corresponding stationary members in
synchronism with the start and stop of the application of the
magnetic: field of the magnetic field apply unit.
[0032] According to another embodiment, there is provided a
magnetic refrigeration system comprising:
[0033] a plurality of magnetic refrigeration devices arranged
substantially along a circle and each including
[0034] a stationary members arranged in parallel with each other,
with gaps defined between adjacent ones of the stationary members,
each of the stationary members being formed of one of a magnetic
body having a magnetocaloric effect, and a solid heat accumulation
member having a heat accumulation effect, the adjacent ones of the
stationary members opposing each other; and a plurality of movable
members arranged in.
[0035] parallel with each other, and permitted to be brought into
contact with the adjacent stationary members within the respective
gaps and thermally connected to the adjacent stationary members,
each of the movable members being formed of the other of the
magnetic body and the solid heat accumulation member;
[0036] at least one magnetic field apply unit provided along the
circle over or below the plurality of magnetic refrigeration
devices and configured to start and stop application of a magnetic
field to the magnetic body; and
[0037] a moving mechanism circle configured to selectively bring
the movable members to the corresponding stationary members in
synchronism with the start and stop of the application of the
magnetic field of the magnetic field apply unit.
[0038] Referring to the accompanying drawings, descriptions will be
given of magnetic refrigeration devices and magnetic refrigeration
systems incorporating the magnetic refrigeration devices, according
to embodiments.
First Embodiment
[0039] FIG. 1 shows a magnetic refrigeration system according to a
first embodiment. This magnetic refrigeration system comprises a
magnetic refrigeration device 1. The magnetic refrigeration device
1 has the following structure. A plurality of plate-like solid heat
accumulation members 3, which have a heat accumulation function and
are formed rigid, are arranged in parallel to each other. The solid
heat accumulation members 3 are provided as stationary members.
Spaces 4 are defined between the respective pairs of the adjacent
solid heat accumulation members. Plate-like magnetic bodies 2,
which have a magnetocaloric effect and are flexible, are provided
in the spaces 4 defined between the respective pairs of the
adjacent solid heat accumulation members 3, and are arranged in
parallel to each other. The magnetic bodies 2 are provided as
movable members. The magnetic bodies can be brought into thermal
contact with the adjacent solid heat accumulation members 3. The
solid heat accumulation members 3 and the magnetic bodies 2 are
arranged alternately. Spacers 5 that define the spaces 4 are
provided between the adjacent solid heat accumulation members 3
such that they support the opposite ends of each of the magnetic
bodies 2.
[0040] Each plate-like magnetic body 2 has a first surface 2-1 kept
in contact with one inner surface 3-1 of one of the two solid heat
accumulation members adjacent to said each magnetic body 2, and
also has a second surface 2-2 opposing one surface 3-2 of the other
of the two solid heat accumulation members 3. The magnetic
refrigeration system also comprises a contact drive unit 10 capable
of moving the plate-like magnetic bodies 2 in directions N relative
to the solid heat accumulation members 3. The contact drive unit 10
is formed of for example, a voltage driving mechanism for
electrostatically driving the plate-like magnetic bodies 2.
[0041] In the electrostatic drive mechanism, first and second
voltages are selectively applied from the outside to the plate-like
magnetic bodies 2 and the solid heat accumulation members 3. When
the first voltage is applied to the plate-like magnetic bodies 2
and the solid heat accumulation members 3, the inner surface 3-1 of
the aforementioned one solid heat accumulation member 3 is brought
into contact with the first surface 2-1 of said each plate-like
magnetic body 2 if the applied voltage is switched from the first
voltage to the second voltage, said each plate-like magnetic body 2
is deformed toward the inner surface 3-2 of the other solid heat
accumulation member 3 to thereby bright the second surface 2-2 of
said each magnetic body 2 into contact with the inner surface 3-2.
After that, if the applied voltage is switched from the second
voltage to the first voltage, said each plate-like magnetic body 2
is deformed toward the inner surface 3-1 of the one solid heat
accumulation member 3 to thereby bright the first surface 2-1 into
contact with the inner surface 3-1.
[0042] The operation of the magnetic refrigeration device 1 will
now be described in detail. When each magnetic body 2 generates
heat, the first surface 2-1 thereof is brought into contact with
the inner surface 3-1 of the one solid heat accumulation member 3.
As a result, the heat is conducted from said each magnetic body 2
to the one solid heat accumulation member 3 to thereby increase the
temperature of the one solid heat accumulation member 3. Further,
as will be described in detail, when each magnetic body 2 absorbs
heat, the second surface 2-2 thereof is brought into contact with
the inner surface 3-2 of the other solid heat accumulation member
3, with the result that the heat of the other solid heat
accumulation member 3 is absorbed by said each magnetic body 2 and
is therefore cooled.
[0043] The solid heat accumulation member located on one outermost
side of the magnetic refrigeration device 1 is kept in thermal
contact with a high-temperature-side heat exchanger 7, while the
solid heat accumulation member 3 located on the other outermost
side of the magnetic refrigeration device 1 is kept in thermal
contact with a low-temperature-side heat exchanger 8. When the
magnetic refrigeration device 1 performs heat
absorption/dissipation as described above, heat is conducted from
the low-temperature-side heat exchanger 8 side to the
high-temperature-side heat exchanger 7 side, whereby the heat of
the low-temperature-side heat exchanger 8 is most absorbed and the
temperature of the high-temperature-side heat exchanger 7 is most
increased. As a result, the exchanger 8 is cooled and the heat of
the exchanger 7 is externally dissipated.
[0044] Along the longitudinal axis of the magnetic refrigeration
device 1, magnetic field apply units 6A and 6B are provided so that
they can move in a direction M parallel to the longitudinal axis.
When the magnetic field apply units 6A and 6B move in the direction
M, they apply magnetic fields to the magnetic bodies 2. On the
other hand, when the magnetic field apply units 6A and 6B move in
the direction opposite to the direction M, the applied magnetic
fields gradually disappear. In synchronism with the application and
elimination of the magnetic fields of the magnetic field apply
units 6A and 6B, the contact drive unit 10 is operated to bring
each magnetic body 2 into contact with one of the corresponding
adjacent solid heat accumulation members 3. As a result, in the
magnetic refrigeration device 1, heat is conducted by heat
absorption or heat dissipation occurring in the magnetic bodies 2,
whereby the low-temperature-side heat exchanger 8 is cooled and the
high-temperature-side heat exchanger 7 dissipates heat.
[0045] As described above, the magnetic refrigeration device of the
first embodiment does not require a power source, such as a pump,
for moving a refrigerant, and hence can increase the rate of
refrigeration cycle. Accordingly, the magnetic refrigeration device
of the first embodiment can be made compact and to have a high
output. Further, if the magnetic refrigeration device of the first
embodiment is used in a magnetic refrigeration system, the system
can be made compact and to have a high output.
[0046] Although in the magnetic refrigeration device 1 shown in
FIG. 1, the magnetic bodies 2 are formed as movable members having
flexibility, the magnetic refrigeration device i may be modified
such that the magnetic bodies 2 have rigidity and are immovably
fixed in position, and the solid heat accumulation members 3 are,
instead, formed as movable members having flexibility. Namely, in
the magnetic refrigeration device 1 shown in FIG. 1, the solid heat
accumulation members 3 may be formed as movable (deformable)
members having flexibility so that they is movable (deformable) in
the direction N. In this case, each solid heat accumulation member
3 is deformed and brought into contact with the corresponding rigid
magnetic bodies 2 opposing each other.
[0047] Further, although in the magnetic refrigeration device 1
shown in FIG. 1, the magnetic bodies 2 as movable members have a
structure in which they are formed of a single material to have
deformable flexibility at their proximal ends, they may each have a
structure as shown in FIG. 2A, which comprises a contact portion 2A
to be brought into contact with the corresponding solid heat
accumulation members 3 as stationary members, and support portions
2B supporting the contact portion 2A. For instance, the support
members 2B may preferably have a flexible structure formed of a
material having a high fatigue resistance, such as iron, since they
will repetitively receive pressure,
[0048] Furthermore, to prevent fatigue breaking, the magnetic
bodies 2 may be constructed as shown in FIG. 2B. In this case, the
support portions 2B of the magnetic bodies 2 as movable members are
not fixed, but are slidable along guides 9 that are employed in
place of the spacers 6 and extend along the longitudinal axis of
the device 1 (i.e., extend parallel to the direction N). Along the
guides 9, the magnetic bodies 2 are brought into contact with the
solid heat accumulation members 3. Alternatively, each magnetic
body 2 as a movable member may be constructed as shown in FIG. 2C
such that it is not fixed at any portion thereof, and is smoothly
movable in the direction N on the corresponding spacer 5 in the
corresponding gap 4.
[0049] If the solid heat accumulation members 3 are formed flexible
instead of the magnetic bodies 2 as mentioned, above, they may have
the structures of FIGS. 2A to 2C, like the magnetic bodies 2 shown
in FIGS. 2A to 2C.
[0050] The magnetic bodies 2 having a magnetocaloric effect,
according to the first embodiment, are not limited in material. It
is sufficient if the magnetic bodies exhibit the magnetocaloric
effect. For instance, the magnetic bodies may be formed of Gd
(Gadolinium), a Gd compound mixed with various elements, an
intermetallic compound comprising various rare earth elements and
transition metal elements, an Ni.sub.2MnGa alloy, a GdGeSi-based
compound, an LaFe.sub.13-based compound, an LaFe.sub.13H-based
compound, etc. Further, the magnetic bodies are not limited to the
plate-like shape, but may have other shapes, such as foil or the
aforementioned flexible shapes.
[0051] The solid heat accumulation members 3 of the first
embodiment are not limited in material, but may be formed of a
metal, such as Al (aluminum), Cu (copper), Fe (iron) or stainless
steel, or of a non-metallic material, such as silicon or carbon, or
of ceramic, such as AlN (aluminum nitride), SIC (silicon carbide),
alumina, or a composite of these materials. However, in light of
speedup of the magnetic refrigeration cycle, it is preferable to
select a material of a high heat conductivity. Further, the solid
heat accumulation members 3 are not limited to the plate-like
shape, but may have other shapes, such as foil or the
aforementioned flexible shapes.
[0052] In consideration of thermal conduction, the magnetic bodies
2 and the solid heat accumulation members 3 may preferably be
formed to have thicknesses and areas so that they have
substantially the same heat capacity,
[0053] The magnetic field apply units 6A and 6B are arranged
outside the magnetic refrigeration device 1, with the device 1
interposed therebetween, thereby forming a magnetic circuit. The
magnetic field apply units 6A and 6B may be formed of permanent
magnets or electromagnets.
[0054] The magnetic field apply units 6A and 6B can be moved in the
direction indicated, by arrows N in FIG. 1 by a moving mechanism
(not shown). As mentioned above, by moving the magnetic field apply
units 6A and 6B, application and removal of a magnetic field to and
from the magnetic bodies 2 can be realized.
[0055] When the magnetic field apply units 6A and 6B are formed of
electromagnets, application and removal of a magnetic field to and
from the magnetic bodies 2 can be realized simply by
permitting/interrupting the flow of current through the magnets,
without moving the units 6A and 6B. Thus, in this case, no moving
mechanism is necessary.
[0056] Referring now to FIGS. 3A and 3B, the principle of basic
heat conduction in the magnetic refrigeration device 1 will be
described in more detail.
[0057] FIG. 3A shows a state in which the magnetic field apply
units 6A and 6B apply a magnetic field to the magnetic body 2. When
the magnetic field apply units 6A and 6B apply a magnetic field to
the magnetic body 2, the temperature of the magnetic body 2 is
increased by the magnetocaloric effect. At this time, the magnetic
body 2 is in contact with the solid heat accumulation member 3A,
and the heat produced is conducted to the solid heat accumulation
member 3A. Subsequently, as shown in FIG. 3B, the magnetic field
apply units 6A and 6B are moved or are stopped to generate a
magnetic field, thereby causing the magnetic field to disappear. As
a result, the temperature of the magnetic body is reduced by the
magnetocaloric effect. In accordance with the reduction of the
temperature of the magnetic body, the magnetic body 2 is brought
into contact with the solid heat accumulation member 3B, whereby
heat is conducted from the solid heat accumulation member 3B to the
magnetic body 2 if this operation is repeated in an adiabatic
state, the heat is conducted from the solid heat accumulation
member 3B to the solid heat accumulation member 3A, whereby a
temperature difference will occur by a thermal storage effect
between the accumulation members 3A and 3B.
[0058] The magnetic refrigeration device 1 shown in FIG. 1 has a
stacked structure in which a plurality of unit structures similar
to that shown in FIG. 3A are stacked. In this structure,
temperature differences caused by the unit structures are held.
Thus, in the magnetic refrigeration device 1, a great temperature
difference is obtained at the opposite ends of the device.
[0059] Further, in the magnetic refrigeration device 1, the heat
conducted to an end of the stacked structure is dissipated to the
outside via the high-temperature-side heat exchanger 7. In
contrast, at the lower temperature end, heat is absorbed from the
outside via the low-temperature-side heat exchanger 8. The
high-temperature-side heat exchanger 7 and the low-temperature-side
heat exchanger 8 are formed of, for example, Cu (copper) of a high
thermal conductivity.
Second Embodiment
[0060] Referring then to FIG. 4, a description will be given of a
magnetic refrigeration system according to a second embodiment. In
the magnetic refrigeration system shown in FIG. 4, each magnetic
body 2 (movable member) in the magnetic refrigeration device 1 is
kept away from one of the corresponding solid heat accumulation
member 3 and kept in contact with the other solid heat accumulation
member 3 (stationary member) by the magnetic attractive forces
applied by external magnetic fields. Namely, switching of magnetic
member pairs is realized by the driving forces based on the
magnetic attractive forces applied by the external magnetic
fields.
[0061] In the magnetic refrigeration device 1 incorporated in the
magnetic refrigeration system of the second embodiment shown in
FIG. 4, the magnetic bodies 2 are constructed as movable members.
By moving the magnetic field apply units 6A and 6B, application and
removal of a magnetic field to and from the magnetic bodies 2 are
realized, whereby the temperature of the magnetic bodies 2 are
increased or reduced as a result of the magnetocaloric effect. At
the same time, magnetic attractive forces are exerted between the
magnetic field apply units 6A and 6B and the magnetic bodies 2.
Accordingly, when the magnetic field apply units 6A and 6B are
moved rightward in FIG. 4, the temperatures of the magnetic bodies
2 as movable members, toward which the magnetic field apply units
6A and 6B move, increase. At the same time, the proximal ends of
the magnetic bodies 2 are successively attracted and deformed by
the magnetic attractive forces of the magnetic field apply units 6A
and 6B. As a result, each magnetic body 2 itself is moved leftward
and brought into contact with the right surface of the
corresponding solid heat accumulation member 3 as indicated by
arrow L, to conduct its heat to the surface. When the magnetic
field apply units 6A and 6B are moved away from said each magnetic
body 2, the temperature of said each magnetic body 2 as a movable
member reduces. At the same time, said each magnetic body 2 is
moved rightward and brought into contact with the left surface of
the corresponding solid heat accumulation member 3 by the magnetic
attractive forces of the magnetic field apply units 6A and 6B, as
is indicated by arrow R, thereby absorbing the heat thereof. As a
result of the above-mentioned series of operations, heat is
conducted from the low-temperature side heat exchanger 8 to the
high-temperature-side heat exchanger 7, and a temperature
difference occurs because of thermal accumulation effect between
the solid heat accumulation members 3 located at opposite ends of
the device 1.
Third Embodiment
[0062] Referring then to FIG. 5, a magnetic refrigeration system
according to a third embodiment will be described in a magnetic
refrigeration device 1 incorporated in the magnetic refrigeration
system shown in FIG. 5, the forces for driving a magnetic body 2
(movable member) are imparted as electrostatic forces, whereby the
solid heat accumulation member 3 (stationary member), with which
the magnetic body 2 is brought into contact, is switched between
the two solid heat accumulation members 3.
[0063] FIG. 5 shows the unit structure of the magnetic
refrigeration device 1. In this device, it is sufficient if either
the magnetic body 2 or the solid heat accumulation member 3 is set
as a movable member. In the second embodiment shown in FIG. 5, the
magnetic body 2 is set as a movable member. A voltage is applied
between the magnetic body 2 and each of the solid heat accumulation
members 3A and 3B for generating an electrostatic force
therebetween. The solid heat accumulation members 3A and 3B are
formed of a conductive material that can serve as an electrode.
Further, an insulation layer (dielectric layer) 9 is provided on
the surface of each of the solid heat accumulation members 3A and
3B that oppose the magnetic body 2. A switching circuit 12 serving
as a driving circuit and capable of switching the voltage polarity
of the magnetic body 2 or the solid heat accumulation members 3A
and 3B is connected to the magnetic refrigeration device 1.
[0064] In the circuit shown in FIG. 5, the positive and negative
electrodes of a voltage source 13 are connected to the first
terminals of a switching circuit 14, and the positive electrode of
the voltage source 13 is also connected to the magnetic body 2. The
second terminals of the switching circuit 14 are connected to the
solid heat accumulation members 3A and 3B, Further, the switching
circuit 14 has switch elements fixed to the first terminals and
movable simultaneously with each other. Each of the switch elements
is selectively connected to the corresponding two second terminals.
By virtue of this structure, when the positive electrode of the
voltage source 13 is connected to one of the solid heat
accumulation members 3A and 3B, the negative electrode of the
voltage source 13 is connected to the other of the solid heat
accumulation members 3A and 3B. In contrast, when the positive
electrode of the voltage source 13 is connected to the other of the
solid heat accumulation members 3A and 3B, the negative electrode
of the voltage source 13 is connected to the one of the solid heat
accumulation members 3A and 3B. In the example of FIG. 5, the
switch elements of the switching circuit 14 are connected to the
second terminals so that a positive bias is applied to the magnetic
body 2 and the other solid heat accumulation member 3B, and a
negative bias is applied to the one solid heat accumulation member
3A. In this state, a repulsive (electrostatic) force is exerted
between the magnetic body 2 and the solid heat accumulation member
3B, and an attractive (electrostatic) force is exerted between the
magnetic body 2 and the solid heat accumulation member 3A, with the
result that the magnetic body 2 as a movable member is brought into
contact with the solid heat accumulation member 3A. In contrast,
when the switch elements of the switching circuit 14 are switched
to be connected to the other two second terminals, the positive
bias is applied to the magnetic body 2 and the other solid heat
accumulation member 3A, and the negative bias is applied to the
other solid heat accumulation member 3B, with the result that the
magnetic body 2 is brought into contact with the solid heat
accumulation member 3B.
[0065] By thus synchronizing the operation of the magnetic body 2
as a movable member with the application and removal, of magnetic
fields, using electrostatic forces, as is shown in FIGS. 3 and 4, a
magnetic refrigeration cycle is realized.
[0066] Although in the magnetic refrigeration device 1 of the third
embodiment shown in FIG. 5, the insulation layers (dielectric
layer) 9 are, provided on the surfaces of the solid heat
accumulation members 3A and 3B, they may be provided on the
surfaces of the magnetic bodies 2 and/or on the surfaces of the
solid heat accumulation members 3A and 3B. By integrally forming
the insulation layers 9 on the overall surfaces of the magnetic
bodies and/or the solid heat accumulation members, thermal
resistance can be reduced. It is preferable to form the insulation
layers 9 of a material of high thermal conductivity, such as
diamond-like carbon,
Fourth Embodiment
[0067] Referring to FIG. 6, a magnetic refrigeration system
according to a fourth embodiment will be described. In a magnetic
refrigeration device 1 incorporated in the magnetic refrigeration
system shown in FIG. 6, driving forces for the magnetic body 2
(movable member) are given as electrostatic forces, and the solid
heat accumulation member (movable member), with which each magnetic
body 2 is brought into contact, is switched between the one solid
heat accumulation member 3 (stationary member) and the other solid
heat accumulation member 3 (stationary member).
[0068] The magnetic refrigeration device shown in FIG. 6 is
constructed as a device comprising a plurality of stacked basic
units similar to the basic unit shown in FIG. 5. In the
unit-stacked magnetic refrigeration device of FIG. 6, the magnetic
bodies 2 as movable members are simultaneously operated in one
direction or the other direction indicated by arrows N FIGS. 7 and
8 show operation examples of the device of FIG. 6, More
specifically, FIG. 7 shows a state in which magnetic fields are
applied to the magnetic refrigeration device 1 by the magnetic
field apply units 6A and 6B. In the state of FIG. 7, the
temperatures of the magnetic bodies 2 are increased by the
magnetocaloric effect, and are brought into contact with the
corresponding left-side solid heat accumulation members 3 by
electrostatic forces, whereby the magnetic bodies 2 dissipate heat
to the solid heat accumulation members 3. FIG. 8 shows a state (a
magnetic-field eliminated state) in which the magnetic fields
applied to the magnetic refrigeration device 1 by the magnetic
field apply units 6A and 6B are eliminated. In the magnetic-field
eliminated state, the magnetic bodies 2 are reduced in temperature
due to the magnetocaloric effect, and are brought into contact with
the corresponding right-side solid heat accumulation members 3 by
electrostatic forces, whereby the solid heat accumulation members 3
absorb heat from the magnetic bodies 2. By the series of operations
mentioned above, heat is conducted from the low-temperature-side
heat exchanger 8 to the high-temperature-side heat exchanger 7, and
a temperature difference is given between the opposite ones of the
solid heat accumulation members 3 by the magnetocaloric effect.
[0069] A description will now be given of a modification of the
fourth embodiment, in which each of the magnetic bodies 2 as
movable members in the magnetic refrigeration device 1 is
controlled in accordance with movement of the magnetic field apply
units 6A and 6B. In this case, as shown in FIG. 9, by forming each
of the solid heat accumulation members 3 as stationary members to
have a two-layer structure comprising first and second stationary
pieces 3A and 3B, the magnetic bodies 2 (movable members) can be
operated independently of each other. The stationary members 3A and
3B as the first, and second stationary pieces can be realized by
configuring the switching circuit 12 so that a positive or negative
polarity voltage can be applied to the circuit independently of
each other. When a positive bias is applied to the solid heat
accumulation members 3A and 3B, the magnetic bodies 2, to which a
positive bias is applied, are moved away from the solid heat
accumulation members 3A and 3B as the first and second stationary
pieces. In contrast, when a negative bias is applied to the solid
heat accumulation members 3A and 3B, the magnetic bodies 2 are
brought into contact with the members 3A and 3B, as the first and
second stationary pieces.
[0070] Alternatively, the magnetic bodies 2 as movable members may
be efficiently moved utilizing both the magnetic attractive forces
and the electrostatic attractive forces described in the second and
third embodiments. FIGS. 10A, 10B and 10C are views useful in
explaining how the magnetic bodies 2 as movable members are moved
by both the magnetic attractive forces and the electrostatic
attractive forces. A bias is applied to the magnetic refrigeration
device 1 so that electrostatic attractive forces are applied in the
forwarding direction M of the magnetic field apply units 6A and 6B,
as shown in FIG. 10A. More specifically, a positive potential is
applied to the solid heat accumulation member 3A (in FIGS. 10A to
100, the left-hand solid heat-hand accumulation member 3A) located
upstream of the magnetic body 2 and the magnetic field apply units
6A and 6B in the forwarding direction M, and a negative potential
is applied to the solid heat accumulation member 36 (in FIGS. 10A
to 10C, the right-hand solid heat accumulation member 3B) located
downstream of the magnetic body 2 and the magnetic field apply
units 6A and 6B in the forwarding direction M. Accordingly, an
electrostatic repulsive force is exerted between the magnetic body
2 and the left-hand solid heat accumulation member 3A, while an
electrostatic attractive force is exerted between the magnetic body
2 and the right-hand solid heat accumulation member 3B. As a
result, the magnetic body 2 is brought into contact with the
right-hand solid heat accumulation member 3B. The magnetic
attractive forces generated by the magnetic field apply units 6A
and 6B are each designed to be higher than the electrostatic
attractive force. Therefore, in this magnetic refrigeration device,
when the magnetic field apply units 6A and 6B approach the magnetic
body 2, a magnetic field is applied to the magnetic body 2 to cause
the magnetic body 2 to generate heat. Further, at this time, since
the magnetic attractive force is greater than the electrostatic
attractive force, the magnetic body 2 contacting the right-hand
solid heat accumulation member 3B is moved toward the magnetic
field apply units 6A and 6B (in the direction indicated by arrow L)
and then brought into contact with the left-hand solid heat
accumulation member 3A. When the magnetic field apply units 6A and
6B are moved and the magnetic fields applied to the magnetic body 2
are weakened, the temperature of the magnetic body 2 reduced and
the electrostatic attractive force becomes greater than the
magnetic attractive force. As a result, the magnetic body 2 is
moved in the forwarding direction of the magnetic field apply units
6A and 6B (in the direction indicated by arrow R) and then brought
into contact with the right-hand solid heat accumulation member 3B,
as is shown in FIG. 10C. Repetition of the above operations causes
conduction of heat from the low-temperature-side heat exchanger 8
to the high-temperature-side heat exchanger 7.
[0071] Although in the embodiment of FIGS. 10A to 10C, system is
described in which the magnetic field apply units 6A and 6B are
moved in one direction along the magnetic body 2, another system
may be employed in which the magnetic field apply units 6A and 6B
are reciprocated along the magnetic body 2.
Fifth Embodiment
[0072] In a magnetic refrigeration system according to a fifth
embodiment, the pressure in each space 4 of the magnetic
refrigeration device 1 is kept low. Since each space 4 in the
magnetic refrigeration device 1 is reduced in pressure, the thermal
resistance therein is increased to thereby suppress reverse flow of
heat from the high-temperature side to the low-temperature side,
i.e., to enhance the thermal conduction efficiency.
[0073] The magnetic refrigeration system of the fifth embodiment is
realized by containing the magnetic refrigeration device 1 in a
sealed decompression container 21 as shown in FIG. 11.
[0074] The decompression container 21 is formed of a non-magnetic
material, e.g., a resin such as plastic. Alternatively, the
decompression container 12 may be formed of a metal, such as
aluminum, to enhance its strength. However, in view of suppression
of occurrence of eddy current due to elimination of magnetic
fields, or in view of adiabatic performance, it is desirable to
form the decompression container 12 of a resin having a high
electrical resistance.
[0075] The magnetic refrigeration devices shown in FIGS. 1 to 11
can be realized as such a magnetic refrigeration system as shown in
FIG. 12.
[0076] FIG. 12 is a schematic perspective view illustrating the
magnetic refrigeration system of the fifth embodiment. Four
magnetic refrigeration devices 1 having the structure shown in FIG.
1 are provided along a first circle, and two pairs of magnetic
field apply units 6A and 6B are provided along second and third
circles coaxially defined over and below the first circle. As one
example, two magnetic field apply units 6A are secured to an upper
rotary plate 30A that defines the second circle, and two magnetic
field apply units 6B are secured to a lower rotary plate 30B that
defines the third circle. The four magnetic refrigeration devices 1
are structured as a magnetic refrigeration device unit that
includes the solid heat accumulation members 3 and the magnetic
bodies 2 and excludes the contact drive unit 10 and the magnetic
field apply units 6A and 6B.
[0077] The upper and lower rotary plates 30A and 30B are secured to
a rotary shaft 32 located at the center of the first circle along
which the magnetic refrigeration devices 1 are provided. About the
rotary shaft 32, the upper and lower rotary plates 30A and 30B are
rotated in synchronism with each other. The rotary shaft 32 is
rotated by, for example, a motor (not shown). In accordance with
the rotation, the magnetic field apply units 6A and 6B are
repeatedly and simultaneously made to approach each magnetic
refrigeration device 1 and depart therefrom. The repeated
approaching and departing from the magnetic refrigeration devices 1
cause heat conduction in the devices 1 as mentioned above.
[0078] Further, although in the system of the fifth embodiment, two
pairs of magnetic field apply units 6A and 6B are provided on the
rotary plates 30A and 30B, one pair of, or three or more pairs of
magnetic field apply units 6A and 6B may be provided. In view of
stabilizing the rotation of the rotary plates 30A and 30B, it is
desirable to arrange pairs of magnetic field apply units 6A and 6B
point-symmetrical with respect to the rotary shaft 32.
[0079] Yet further, although in the system of the fifth embodiment,
four magnetic refrigeration devices 1 are provided along the same
circle, one to three magnetic refrigeration devices 1, or five or
more magnetic refrigeration devices 1, may be provided.
[0080] FIG. 13 is a schematic plan view illustrating the
configuration of a magnetic refrigeration system according to a
sixth embodiment. As shown in FIG. 13, four magnetic refrigeration
devices 1-1, 1-2, 1-3 and 1-4 are provided between the upper and
lower rotary plates 30A and 30B along the some circle.
[0081] As shown, high-temperature-side heat exchangers 7-1, 7-2,
7-3 and 7-4 corresponding to the four magnetic refrigeration
devices 1-1, 1-2, 1-3 and 1-4 are connected to a heat dissipation
unit 34 thermally in parallel with each other. Similarly,
low-temperature-side heat exchangers 8-1, 8-2, 8-3 and 8-4
corresponding to the four magnetic refrigeration devices 1-1, 1-2,
1-3 and 1-4 are connected to a heat absorption unit 36 thermally in
parallel with each other.
[0082] The heat produced by a magnetic refrigeration cycle at the
high-temperature-side heat exchangers 7-1, 7-2, 7-3 and 7-4 is
conducted to the heat dissipation unit 34 via, for example, heat
exchangers 37-1, 37-2, 37-3 and 37-4. On the other hand, the cold
energy produced by a magnetic refrigeration cycle at the
low-temperature-side heat exchangers 8-1, 8-2, 8-3 and 8-4 is
conducted to the heat absorption unit 36 via, for example, heat
exchangers 38-1, 38-2, 38-3 and 38-4.
[0083] Conduction of heat and cold energy to the heat dissipation
unit 34 and the heat absorption unit 36 indicated by the solid and
broken lines in FIG. 13 can be realized utilizing a known heat
exchanging gas or liquid, or utilizing solid heat conduction.
[0084] FIG. 14 is a schematic plan view illustrating the structure
of a magnetic refrigeration system according to a seventh
embodiment. In the seventh embodiment shown in FIG. 14, four
magnetic refrigeration devices 1-1, 1-2, 1-3 and 1-4 are connected
thermally in series, unlike the sixth embodiment shown in FIG.
13.
[0085] The adjacent ends of the magnetic refrigeration devices 1-1,
1-2, 1-3 and 1-4 are connected to each other via heat conductors
40-1, 40-2 and 40-3. A high-temperature-side heat exchanger 7 is
coupled to the other end of the magnetic refrigeration device 1-1
as an end device of the four magnetic refrigeration devices 1-1,
1-2, 1-3 and 1-4, and is connected to a heat dissipation unit 34
via a heat conductor 42-1. Similarly, a low-temperature-side heat
exchanger 8 is coupled to the other end of the magnetic
refrigeration device 1-4 as the other end device, and is connected
to a heat absorption unit 36 via a heat conductor 42-2.
[0086] Further, the magnetic transition temperature of the magnetic
bodies of the magnetic refrigeration device 1-1 with the
high-temperature-side heat exchanger 7 is set higher than that of
the magnetic bodies of the magnetic refrigeration device 1-4 with
the low-temperature-side heat exchanger 8. For instance, the
magnetic transition temperature is gradually reduced in the order
of from the magnetic bodies of the magnetic refrigeration device
1-1 with the high-temperature-side heat exchanger 7, through the
magnetic bodies of the adjacent magnetic refrigeration devices 1-2
and 1-3, to the magnetic bodies of the last magnetic refrigeration
device 1-4 with the low-temperature-side heat exchanger 8. Thus,
the magnetic bodies of the last magnetic refrigeration device 1-4
has the lowest magnetic transition temperature.
[0087] In the refrigeration magnetic refrigeration system of the
seventh embodiment shown in FIG. 14, the high-temperature-side heat
exchanger 7 of the magnetic refrigeration devices constructed as
above is thermally connected to the heat dissipation unit 34, and
the low-temperature-side heat exchanger 8 is thermally connected to
the heat absorption unit 36.
[0088] Since in the embodiment of FIG. 14, magnetic refrigeration
devices with magnetic bodies having different magnetic transition
temperatures are connected in series, a high magnetic refrigeration
temperature difference can he obtained.
[0089] The above-described embodiments are merely examples, and the
elements of the embodiments may be combined appropriately.
[0090] Further, although in the above embodiments, the magnetic
field apply units of the magnetic field apply/eliminate mechanism
are rotated, they may be reciprocated with respect to the magnetic
refrigeration devices. In this case, it is preferable to use a
linear driving actuator or a cam mechanism for converting the
rotational motion into linear motion. Furthermore, the relative
motion of the magnetic field apply units and the magnetic
refrigeration devices may be manually realized, or be realized
utilizing part of the driving force of a vehicle, or utilizing
natural energy, such as wind, power, wave power or water power.
[0091] Although in the above embodiments, the elements, which may
be incorporated in the magnetic refrigeration device or system,
have not been described, the elements required for the magnetic
refrigeration device or system may be selected and used
appropriately.
[0092] As described above, the magnetic refrigeration devices of
the embodiments do not require a refrigerant and hence can realize
a high-speed refrigeration cycle. Accordingly, it is possible to
provide a compact magnetic refrigeration device of a high output.
Further, it is also possible to provide a compact magnetic
refrigeration system of a high output by incorporating therein the
high-output compact magnetic refrigeration device.
[0093] Thus, there is provided a compact, high-output magnetic
refrigeration device and system of a high refrigeration
efficiency.
[0094] 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.
* * * * *