Magnetic refrigerator

A magnetic refrigerator including an electromagnet for magnetic refrigeration. The electromagnet for magnetic refrigeration includes: a return yoke; at least one pair of opposite magnetic poles disposed inside the return yoke and spaced from each other by a gap; a pipe disposed in the gap to pass a heat transport medium therethrough; a magnetocaloric member disposed inside the pipe to exchange heat with the heat transport medium; and a coil to surround at least one of the paired opposite magnetic poles to generate a magnetic flux passing across the gap when the coil is energized.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is based on PCT filing PCT/JP2020/019338, filed May 14, 2020, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a magnetic refrigerator.

BACKGROUND ART

Magnetic refrigeration technology is known as environmentally-conscious refrigeration technology. Magnetic refrigeration technology utilizes a magnetocaloric effect, that is, when a magnetic field is applied to a substance referred to as a magnetocaloric material in an adiabatic state, the temperature of the magnetocaloric material increases, and when the magnetic field is removed therefrom, the temperature of the magnetocaloric material decreases.

Japanese Patent Application Laying-Open No. 2004-361061 discloses a magnetic refrigerator comprising a storage body in which a magnetocaloric material is stored, and an air core coil disposed so as to surround the storage body.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

For the magnetic refrigerator described in Japanese Patent Laying-Open No. 2004-361061, however, the storage body having the magnetocaloric material stored therein is disposed inside the air core coil, and it is difficult to enhance a magnetic field applied to the magnetocaloric material, and it is difficult to increase a difference in temperature of the magnetocaloric material between a state in which the magnetic field is applied thereto and a state in which the magnetic field is removed therefrom. It is thus difficult for the magnetic refrigerator to enhance the magnetocaloric material's endothermic/exothermic effect.

A main object of the present disclosure is to provide an electromagnet for magnetic refrigeration and a magnetic refrigerator capable of enhancing a magnetocaloric material's endothermic/exothermic effect.

Solution to Problem

A magnetic refrigerator according to the present disclosure comprises an electromagnet for magnetic refrigeration. The electromagnet for magnetic refrigeration includes: a return yoke; at least one pair of opposite magnetic poles disposed inside the return yoke and spaced from each other by a gap; a pipe disposed in the gap to pass a heat transport medium therethrough; a magnetocaloric member disposed inside the pipe to exchange heat with the heat transport medium; and a coil to surround at least one of the paired opposite magnetic poles to generate a magnetic flux passing across the gap when the coil is energized.

Advantageous Effects of Invention

According to the present disclosure a magnetic refrigerator capable of enhancing a magnetocaloric material's endothermic/exothermic effect can be provided.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present disclosure will now be described with reference to the accompanying drawings. In the figures, identical or equivalent components are identically denoted and will not be described redundantly.

First Embodiment

As shown inFIG.1, an electromagnet100for magnetic refrigeration according to a first embodiment comprises a return yoke1, a first magnetic pole2, a second magnetic pole3, a third magnetic pole4, a fourth magnetic pole5, a first coil7, and a second coil8.

As shown inFIG.1, return yoke1is in the form of a quadrangular ring for example. InFIG.1, return yoke1has a portion extending in an X direction and a portion extending in a Y direction orthogonal to the X direction. Each portion of return yoke1extends in a Z direction orthogonal to each of the X direction and the Y direction. Note thatFIG.1indicates a first direction A and a second direction B inclined with respect to the X direction and the Y direction. First direction A intersects second direction B, and is orthogonal to second direction B for example. While first direction A may be inclined with respect to the X direction and the Y direction at any angle, the angle is preferably 45 degrees in view of suppressing magnetic saturation (hereinafter simply referred to as saturation) of each of first to fourth magnetic poles2to5.

First to fourth magnetic poles2to5are disposed inside return yoke1. First to fourth magnetic poles2to5are in contact with an inner peripheral surface of return yoke1or magnetically coupled to return yoke1. While material constituting each of return yoke1and first to fourth magnetic poles2to5may be any magnetic material, it includes, for example, at least one selected from the group consisting of iron (Fe), cobalt (Co), and nickel (Ni).

First magnetic pole2is spaced from second magnetic pole3in first direction A by a first gap6A. First magnetic pole2is spaced from fourth magnetic pole5in the Y direction by a center gap6E.

First magnetic pole2has a first portion2A inner than first coil7, which will be described later, in the X direction, and a second portion2B connected to first portion2A and inner than first portion2A in the Y direction. Second portion2B has a surface extending in first direction A, a surface extending in second direction B, and a surface interconnecting the two surfaces and extending in the X direction. Second portion2B has a width in the X direction decreasing from outside toward inside in the Y direction.

Second magnetic pole3is spaced from fourth magnetic pole5in second direction B by a fourth gap6D. Second magnetic pole3is spaced from third magnetic pole4in the X direction by center gap6E.

Second magnetic pole3has a first portion3A located between first and second coils7and8, which will be described later, in the Y direction, and a second portion3B connected to first portion3A and inner than first portion3A in the X direction. Second portion3B has a surface extending in first direction A, a surface extending in second direction B, and a surface interconnecting the two surfaces and extending in the Y direction. Second portion3B has a width in the Y direction decreasing from outside toward inside in the X direction.

Third magnetic pole4is spaced from fourth magnetic pole5in first direction A by a second gap6B.

Third magnetic pole4has a first portion4A located between first and second coils7and8in the Y direction, and a second portion4B connected to first portion4A and inner than first portion4A in the X direction. Second portion4B has a surface extending in first direction A, a surface extending in second direction B, and a surface interconnecting the two surfaces and extending in the Y direction. Second portion4B has a width in the Y direction decreasing from outside toward inside in the X direction.

Fourth magnetic pole5has a first portion5A inner than second coil8in the X direction, and a second portion5B connected to first portion5A and inner than first portion5A in the Y direction. Second portion5B has a surface extending in first direction A, a surface extending in second direction B, and a surface interconnecting the two surfaces and extending in the X direction. Second portion5B has a width in the X direction decreasing from outside toward inside in the Y direction.

First gap6A faces a surface of first magnetic pole2extending at second portion2B in second direction B and a surface of second magnetic pole3extending at second portion3B in second direction B. As shown inFIG.1, when viewed in the Z direction, first gap6A has a longitudinal direction in second direction B and a shorter-side direction in first direction A.

Second gap6B faces a surface of third magnetic pole4extending at second portion4B in second direction B and a surface of fourth magnetic pole5extending at second portion5B in second direction B. As shown inFIG.1, when viewed in the Z direction, second gap6B has a longitudinal direction in second direction B and a shorter-side direction in first direction A.

Third gap6C faces a surface of first magnetic pole2extending at second portion2B in first direction A and a surface of third magnetic pole4extending at second portion4B in first direction A. As shown inFIG.1, when viewed in the Z direction, third gap6C has a longitudinal direction in first direction A and a shorter-side direction in second direction B.

Fourth gap6D faces a surface of second magnetic pole3extending at second portion3B in first direction A and a surface of fourth magnetic pole5extending at second portion5B in first direction A. As shown inFIG.1, when viewed in the Z direction, fourth gap6D has a longitudinal direction in first direction A and a shorter-side direction in second direction B.

Center gap6E faces a surface of first magnetic pole2extending at second portion2B in the X direction, a surface of second magnetic pole3extending at second portion3B in the Y direction, a surface of third magnetic pole4extending at second portion4B in the Y direction, and a surface of fourth magnetic pole5extending at second portion5B in the X direction. Center gap6E is contiguous to each of first to fourth gaps6A to6D.

Electromagnet100for magnetic refrigeration has first and second magnetic poles2and3to form a pair of opposite magnetic poles opposite to each other with first gap6A therebetween, and has third and fourth magnetic poles4and5to form a pair of opposite magnetic poles opposite to each other with second gap6B therebetween.

First gap6A and second gap6B are disposed so as to sandwich center gap6E in second direction B. Third and fourth gaps6C and6D are disposed so as to sandwich center gap6E in first direction A.

A spacing (or gap length) of first gap6A in first direction A is equal for example to a spacing (or gap length) of second gap6B in first direction A. A spacing (or gap length) of third gap6C in second direction B is equal for example to a spacing (or gap length) of fourth gap6D in second direction B. The spacing of each of first to fourth gaps6A to6D is smaller than, for example, a spacing of center gap6E in the X direction, a spacing of center gap6E in the Y direction, a spacing of center gap6E in first direction A, and a spacing of center gap6E in second direction B.

The spacing of each of first to fourth gaps6A to6D is smaller than, for example, a width of first coil7in a direction along the central axis of first coil7(i.e., first direction A) and a width of second coil8in a direction along the central axis of second coil8(i.e., second direction B).

First coil7surrounds first magnetic pole2in the X direction. Second coil8surrounds fourth magnetic pole5in the X direction. First and second coils7and8have their respective central axes extending in the Y direction. When first and second coils7and8are energized, they generate a magnetic flux passing across first gap6A and fourth gap6D and a magnetic flux passing across second and third gaps6B and6C. When first to fourth magnetic poles2to5are each unsaturated, the magnetic flux passing across first gap6A and the magnetic flux passing across second gap6B each extend in first direction A, and the magnetic flux passing across third gap6C and the magnetic flux passing across fourth gap6D each extend in second direction B.

First and second coils7and8are each connected to a power source (a power source114inFIG.3). First and second coils7and8are concurrently energized or concurrently unenergized. In other words, the power source switches a first state in which first and second coils7and8are concurrently energized (seeFIG.4) to a second state in which first and second coils7and8are concurrently unenergized (seeFIG.5), and vice versa.

As shown inFIG.1, electromagnet100for magnetic refrigeration further comprises a first pipe9A, a second pipe9B, a third pipe9C, a fourth pipe9D, a first magnetocaloric member10A, a second magnetocaloric member10B, a third magnetocaloric member10C, and a fourth magnetocaloric member10D.

As shown inFIGS.1and2, first pipe9A is disposed in first gap6A. When viewed in the Z direction, first pipe9A has a longitudinal direction in second direction B and a shorter-side direction in first direction A. First pipe9A has an outer peripheral surface spaced for example from a surface of each of first and second magnetic poles2and3. First pipe9A may have the outer peripheral surface for example in contact with the surface of each of first and second magnetic poles2and3. Inside first pipe9A is disposed first magnetocaloric member10A. First magnetocaloric member10A is held inside first pipe9A.

Second pipe9B is disposed in second gap6B. When viewed in the Z direction, second pipe9B has a longitudinal direction in second direction B and a shorter-side direction in first direction A. Second pipe9B has an outer peripheral surface spaced for example from a surface of each of third and fourth magnetic poles4and5. Second pipe9B may have the outer peripheral surface for example in contact with the surface of each of third and fourth magnetic poles4and5. Inside second pipe9B is disposed second magnetocaloric member10B. Second magnetocaloric member10B is held inside second pipe9B.

Third pipe9C is disposed in third gap6C. When viewed in the Z direction, third pipe9C has a longitudinal direction in first direction A and a shorter-side direction in second direction B. Third pipe9C has an outer peripheral surface spaced for example from a surface of each of first and third magnetic poles2and4. Third pipe9C may have the outer peripheral surface for example in contact with the surface of each of first and third magnetic poles2and4. Inside third pipe9C is disposed third magnetocaloric member10C. Third magnetocaloric member10C is held inside third pipe9C.

Fourth pipe9D is disposed in fourth gap6D. When viewed in the Z direction, fourth pipe9D has a longitudinal direction in first direction A and a shorter-side direction in second direction B. Fourth pipe9D has an outer peripheral surface spaced for example from a surface of each of second and fourth magnetic poles3and5. Fourth pipe9D may have the outer peripheral surface for example in contact with the surface of each of second and fourth magnetic poles3and5. Inside fourth pipe9D is disposed fourth magnetocaloric member10D. Fourth magnetocaloric member10D is held inside fourth pipe9D.

First, second, third and fourth pipes9A,9B,9C, and9D each extend in the Z direction. First, second, third and fourth pipes9A,9B,9C, and9D are each for example a straight pipe. First, second, third and fourth pipes9A,9B,9C, and9D may each for example be a reciprocating pipe formed of a plurality of straight pipes connected in series by a U-shaped pipe.

When electromagnet100for magnetic refrigeration is incorporated in magnetic refrigerator200, first, second, third and fourth pipes9A,9B,9C, and9D each have one and the other ends in the Z direction connected to an inflow/outflow pipe. When electromagnet100for magnetic refrigeration is incorporated in magnetic refrigerator200, first, second, third and fourth pipes9A,9B,9C, and9D pass a heat transport medium therethrough. The heat transport medium passes through each of first, second, third and fourth pipes9A,9B,9C, and9D in the Z direction.

First, second, third and fourth magnetocaloric members10A,10B,10C and10D are composed of a material including a mnagnetocaloric material. The magnetocaloric material is a material having a magnetocaloric effect, and for example includes gadolinium (Gd).

First, second, third and fourth magnetocaloric members10A,10B,10C and10D each have a gap formed therein to pass the heat transport medium therethrough. First, second, third and fourth magnetocaloric members10A,10B,10C and10D are each, for example, an aggregate of particles of a magnetocaloric material and introduced into each of first, second, third and fourth pipes9A,9B,9C, and9D. In this case, the gap is formed between a plurality of particles.

The sum of the width in second direction B of each of first and second magnetocaloric members10A and10B and the width in first direction A of each of third and fourth magnetocaloric members10C and10D is longer than the inner diameter of each of first and second coils7and8.

As shown inFIG.3, magnetic refrigerator200comprises electromagnet100for magnetic refrigeration shown inFIG.1, a first heat exchanger111, a second heat exchanger112, and a pump113.

First heat exchanger111externally releases heat of the heat transport medium generated as it is heated in electromagnet100for magnetic refrigeration and thus has high temperature. That is, first heat exchanger111exchanges heat between the heat transport medium and an external medium, and thus heats the external medium.

Second heat exchanger112allows the heat transport medium to absorb heat from outside second heat exchanger112as the heat transport medium is cooled in electromagnet100for magnetic refrigeration and thus has low temperature. That is, second heat exchanger112exchanges heat between the heat transport medium and the external medium, and thus cools the external medium.

Pump113is, for example, a reciprocating pump. Pump113alternately repeats a first operation and a second operation. In the first operation, pump113delivers the heat transport medium heated in electromagnet100for magnetic refrigeration to first heat exchanger111, and delivers the heat transport medium having absorbed heat at second heat exchanger112to electromagnet100for magnetic refrigeration. In the second operation, pump113delivers the heat transport medium cooled in electromagnet100for magnetic refrigeration to second heat exchanger112, and delivers the heat transport medium having dissipated heat at first heat exchanger111to electromagnet100for magnetic refrigeration.

Magnetic refrigerator200further includes an inflow/outflow pipe121and an inflow/outflow pipe122. Inflow/outflow pipe121interconnects electromagnet100for magnetic refrigeration and first heat exchanger111. Inflow/outflow pipe122interconnects electromagnet100for magnetic refrigeration and second heat exchanger112. First, second, third and fourth pipes9A,9B,9C, and9D are each connected to inflow/outflow pipes121and122such that the pipes are in parallel to one another.

As shown inFIGS.6and7, inflow/outflow pipe121includes a pipe portion121A, a pipe portion121B, a pipe portion121C, and a pipe portion121D. Pipe portion121A is connected to one end of first pipe9A in the Z direction. Pipe portion121B is connected to one end of second pipe9B in the Z direction. Pipe portion121C is connected to one end of third pipe9C in the Z direction. Pipe portion121D is connected to one end of fourth pipe9D in the Z direction.

Inflow/outflow pipe122includes a pipe portion122A, a pipe portion122B, a pipe portion122C, and a pipe portion122D. Pipe portion122A is connected to the other end of first pipe9A in the Z direction. Pipe portion122B is connected to the other end of second pipe9B in the Z direction. Pipe portion122C is connected to the other end of third pipe9C in the Z direction. Pipe portion122D is connected to the other end of fourth pipe9D in the Z direction.

Pipe portion121A and pipe portion121C for example have a portion extending at first magnetic pole2in the Y direction on a surface facing one side in the Z direction, and a portion extending in the Z direction on an outer peripheral surface of return yoke1.

Pipe portion121B and pipe portion121D for example have a portion extending at fourth magnetic pole5in the Y direction on a surface facing one side in the Z direction, and a portion extending in the Z direction on an outer peripheral surface of return yoke1.

Pipe portion122A and pipe portion122C for example have a portion extending at the first magnetic pole2in the Y direction on a surface facing the other side in the Z direction.

Pipe portion122B for example has a portion extending at third magnetic pole4in the Y direction on a surface facing the other side in the Z direction, and a portion which overlaps in the Z direction with the portion of pipe portion122C extending in the Y direction and also extends in the Y direction.

Pipe portion122D for example has a portion extending at second magnetic pole3in the Y direction on a surface facing the other side in the Z direction, and a portion which overlaps in the Z direction with the portion of pipe portion122A extending in the Y direction and also extends in the Y direction.

Pipe portions121B and121D further have a portion extending at each of first and fourth magnetic poles2and5in the Y direction on a surface facing the other side in the Z direction.

First and second coils7and8are disposed, for example, outside each pipe portion.

<Operation of Electromagnet for Magnetic Refrigeration>

As described above, inFIG.4, electromagnet100for magnetic refrigeration is in the first state. That is, inFIG.4, first and second coils7and8are energized concurrently. InFIG.5, electromagnet100for magnetic refrigeration is in the second state. That is, inFIG.5, first and second coils7and8are concurrently unenergized.

FIG.4is the same asFIG.1, although inFIG.4, a line of magnetic induction indicating a direction in which a magnetic flux passes is indicated by a bold solid line, and also indicates a direction of a current of the coil. The line of magnetic induction is represented by a single line (the same applies hereinafter). As shown inFIG.4, in the first state, first and second coils7and8create a magnetic flux passing across first and fourth gaps6A and6D and a magnetic flux passing across second and third gaps6B and6C. As a result, first, second, third and fourth magnetocaloric members10A,10B,10C and10D generate heat, and the heat transport medium passing through each of first, second, third and fourth pipes9A,9B,9C, and9D is heated.

As shown inFIG.5, in the second state, there is no thick solid line as shown inFIG.4, and no magnetic flux is formed across each of first to fourth gaps6A to6D. As a result, first, second, third and fourth magnetocaloric members10A,10B,10C and10D absorb heat, and the heat transport medium passing through each of first, second, third and fourth pipes9A,9B,9C, and9D is cooled.

In magnetic refrigerator200, the first state shown inFIG.4and the second state shown inFIG.5are alternately and repeatedly switched. Pump113performs the first operation in the first state and performs the second operation in the second state. In the first state, the heat transport medium heated at electromagnet100for magnetic refrigeration is delivered from electromagnet100for magnetic refrigeration to first heat exchanger111by pump113. Concurrently, the heat transport medium having absorbed heat of the external medium at second heat exchanger112is delivered to electromagnet100for magnetic refrigeration. Subsequently, the first state is switched to the second state. In the second state, the heat transport medium cooled at electromagnet100for magnetic refrigeration is delivered from electromagnet100for magnetic refrigeration to second heat exchanger112by pump113. Concurrently, the heat transport medium having dissipated heat first heat exchanger111to the external medium is delivered to electromagnet100for magnetic refrigeration. Subsequently, the second state is switched to the first state.

The first state and the second state are switched cyclically for example at a frequency of about 0.1 Hz to 10 Hz. Thus, magnetic refrigerator200acts as a heat pump (a cold heat system).

In electromagnet100for magnetic refrigeration, a magnetic field generated in first gap6A between first and second magnetic poles2and3in the first state is stronger than a magnetic field generated inside an energized air core coil due to the presence of the magnetic pole and return yoke formed of a magnetic body. Therefore, an amount of heat generated in the first state by first magnetocaloric member10A disposed in first gap6A is larger than an amount of heat generated by a magnetocaloric member disposed inside the energized air core coil. A difference in temperature of the first magnetocaloric member10A between the first state and the second state is larger than a difference in temperature of the magnetocaloric member disposed inside the energized air core coil therebetween. Second, third and fourth magnetocaloric members10B,10C and10D are also similar to first magnetocaloric member10A. As a result, an endothermic/exothermic effect of each of first, second, third and fourth magnetocaloric members10A,10B,10C and10D in electromagnet100for magnetic refrigeration is larger than that when a magnetocaloric member is disposed inside an air core coil.

As an electromagnet for magnetic refrigeration according to a comparative example, let us consider a configuration comprising first and second coils7and8and two magnetic poles (opposite magnetic poles) disposed inside each of first and second coils7and8with a single gap posed therebetween and having a longitudinal direction in the X direction. A length of first gap6A in the longitudinal direction for electromagnet100for magnetic refrigeration is longer than a length of the gap in the longitudinal direction for the comparative example, and the former is for example √2 times the latter. In other words, an area of first and second magnetic poles2and3in electromagnet100for magnetic refrigeration that faces first gap6A is larger than an area of the opposite magnetic poles of the comparative example that faces the gap, and the former is for example √2 times the latter. When magnetomotive force (i.e., the number of turns of a coil x the value of a current per turn) is under a fixed condition, a magnetic flux density B is fixed according to Ampere's law.

Specifically, according to Ampere's law, as equation (1), ∫Hd1=NI is established, where H denotes a magnetic field, L denotes a flux path, and NI denotes magnetomotive force. When a magnetic field in the gap is Hg, a flux path in the gap has a length Lg, a magnetic field in the yoke (the return yoke and the opposite magnetic poles) is Hy, and a flux path in the yoke has a length Ly, Hg·Lg+Hy·Ly=NI is established. When this equation is converted into magnetic flux density B with a vacuum having a magnetic permeability μ0and the yoke having a relative magnetic permeability μr, Bg/μ0·Lg+By/(μr·μ0)·Ly=NI is established as equation (2). Further, when the yoke is unsaturated, a magnetic flux density Bg in the gap is substantially equal to a magnetic flux density By in the yoke, and μr becomes as extremely large as about 10,000. Therefore, the second term on the left side of equation (2) can be ignored, and Bg=NI·μ0/Lg is established as equation (3).

According to equation (3), when the flux path in the gap has length Lg having a fixed value and magnetomotive force NI is fixed, magnetic flux density Bg in the gap will be fixed regardless of the area of the magnetic pole facing the gap. Therefore, a magnetic flux passing across first gap6A in electromagnet100for magnetic refrigeration is proportional to an area of first and second magnetic poles2and3facing first gap6A. As a result, electromagnet100for magnetic refrigeration in which the area of first and second magnetic poles2and3facing first gap6A is √2 times that in the comparative example provides a magnetic flux passing across first gap6A which is √2 times that passing across the gap of the comparative example.

Thus, an endothermic/exothermic effect of each of first, second, third and fourth magnetocaloric members10A,10B,10C and10D in electromagnet100for magnetic refrigeration is larger than that in the electromagnet for magnetic refrigeration according to the comparative example.

Further, electromagnet100for magnetic refrigeration allows first, second, third and fourth magnetocaloric members10A,10B,10C and10D to all generate heat in the first state concurrently and all absorb heat in the second state concurrently. Therefore, a difference in temperature of the heat transport medium implemented in electromagnet100for magnetic refrigeration is larger than a difference in temperature of each of a first heat transport medium and a second heat transport medium implemented in an electromagnet101described hereinafter for magnetic refrigeration as a modified example of electromagnet100for magnetic refrigeration.

Modified Example

FIGS.8to10are diagrams showing electromagnet101for magnetic refrigeration that is a modified example of electromagnet100for magnetic refrigeration. Electromagnet101for magnetic refrigeration has a basic configuration similar to that of electromagnet100for magnetic refrigeration except that first and second coils7and8are configured to be different from those of electromagnet100for magnetic refrigeration.

As shown inFIGS.8to10, first coil7surrounds first gap6A, center gap6E, and second gap6B in second direction B. First coil7surrounds a portion of first to fourth magnetic poles2to5facing each of first gap6A, center gap6E, and second gap6B. First coil7has a central axis extending in first direction A. When first coil7is energized it generates a magnetic flux passing across first gap6A and a magnetic flux passing across second gap6B. InFIGS.8and9, a line of magnetic induction is indicated by a thick solid line. When first to fourth magnetic poles2to5are each unsaturated, the magnetic flux passing across first gap6A and the magnetic flux passing across second gap6B each extend in first direction A.

As shown inFIGS.8to10, second coil8surrounds third gap6C, center gap6E, and fourth gap6D in second direction B. Second coil8surrounds a portion of first to fourth magnetic poles2to5facing each of third gap6C, center gap6E, and fourth gap6D. Second coil8has a central axis extending in second direction B. When second coil8is energized, it generates a magnetic flux passing across third gap6C and a magnetic flux passing across fourth gap6D. When first to fourth magnetic poles2to5are each unsaturated, the magnetic flux passing across third gap6C and the magnetic flux passing across fourth gap6D each extend in second direction B.

First and second coils7and8are each connected to a power source (power source114inFIG.3). First and second coils7and8are alternately energized. In other words, the power source switches a third state in which first coil7is energized and second coil8is unenergized (seeFIG.8) to a fourth state in which first coil7is unenergized and second coil8is energized (seeFIG.9), and vice versa.

InFIG.8, electromagnet101for magnetic refrigeration is in the third state. That is, inFIG.8, first coil7is energized and second coil8is unenergized. InFIG.9, electromagnet100for magnetic refrigeration is in the fourth state. That is, inFIG.9, first coil7is unenergized and second coil8is energized.

As shown inFIG.8, in the third state, a magnetic flux passing across first gap6A and a magnetic flux passing across second gap6B are formed by first coil7. This allows first and second magnetocaloric members10A and10B to generate heat, and thus heats the heat transport medium passing through first and second pipes9A and9B. In the third state, the magnetic flux passing across third gap6C and the magnetic flux passing across fourth gap6D are not formed. This allows third and fourth magnetocaloric members10C and10D to absorb heat, and thus cools the heat transport medium passing through third and fourth pipes9C and9D.

As shown inFIG.9, in the fourth state, the magnetic flux passing across third gap6C and the magnetic flux passing across fourth gap6D are formed by second coil8. As a result, third and fourth magnetocaloric members10C and10D generate heat, and thus heats the heat transport medium passing through third and fourth pipes9C and9D. In the fourth state, the magnetic flux passing across first gap6A and the magnetic flux passing across second gap6B are not formed. This allows first and second magnetocaloric members10A and10B to absorb heat, and thus cools the heat transport medium passing through first and second pipes9A and9B.

FIGS.11and12are block diagrams showing a magnetic refrigerator201comprising electromagnet101for magnetic refrigeration. Magnetic refrigerator201comprises a heat pump of a first system shown inFIG.11and a heat pump of a second system shown inFIG.12. The heat pump of the first system is independent of the heat pump of the second system. The heat pump of the first system shown inFIG.11and the heat pump of the second system shown inFIG.12each basically have a configuration similar to that for magnetic refrigerator200shown inFIG.3. Hereinafter, a heat transport medium for the heat pump of the first system will be referred to as a first heat transport medium, and a heat transport medium for the heat pump of the second system will be referred to as a second heat transport medium.

The heat pump of the first system shown inFIG.11includes first and second pipes9A and9B of electromagnet101for magnetic refrigeration, a first heat exchanger111A, a second heat exchanger112A, and a first pump113A. The heat pump of the first system shown inFIG.11does not include third and fourth pipes9C and9D of electromagnet101for magnetic refrigeration.

As shown inFIG.11, the heat pump of the first system has first and second pipes9A and9B connected to each other in parallel. The first heat transport medium is split into first and second pipes9A and9B in electromagnet101for magnetic refrigeration. In the heat pump of the first system, first pump113A performs the first operation when electromagnet101for magnetic refrigeration is in the third state, and first pump113A performs the second operation when electromagnet101for magnetic refrigeration is in the fourth state. Electromagnet101for magnetic refrigeration alternately repeats the third state and the fourth state. First pump113A alternately repeats the first operation and the second operation.

The first heat transport medium heated at electromagnet101for magnetic refrigeration in the third state is delivered from electromagnet101for magnetic refrigeration to first heat exchanger111A by first pump113A. Concurrently, the first heat transport medium having absorbed heat of an external medium at second heat exchanger112A is delivered to electromagnet101for magnetic refrigeration. Subsequently, the third state is switched to the fourth state. The first heat transport medium cooled at electromagnet101for magnetic refrigeration in the fourth state is delivered from electromagnet101for magnetic refrigeration to second heat exchanger112A by first pump113A. Concurrently, the first heat transport medium having dissipated heat to the external medium at first heat exchanger111A is delivered to electromagnet101for magnetic refrigeration. Subsequently, the fourth state is switched to the third state.

The heat pump of the second system shown inFIG.12includes third and fourth pipes9C and9D of electromagnet101for magnetic refrigeration, a third heat exchanger111B, a fourth heat exchanger112B, and a second pump113B. The heat pump of the second system shown inFIG.12does not include first and second pipes9A and9B. As shown inFIG.12, the heat pump of the second system has third and fourth pipes9C and9D connected to each other in parallel. The second heat transport medium is split into third and fourth pipes9C and9D in electromagnet101for magnetic refrigeration. In the heat pump of the second system, second pump113B performs the first operation when electromagnet101for magnetic refrigeration is in the fourth state, and second pump113B performs the second operation when electromagnet101for magnetic refrigeration is in the third state.

The second heat transport medium cooled at electromagnet101for magnetic refrigeration in the third state is delivered from electromagnet101for magnetic refrigeration to fourth heat exchanger112B by second pump113B. Concurrently, the second heat transport medium having dissipated heat to the external medium at third heat exchanger111B is delivered to electromagnet101for magnetic refrigeration. Subsequently, the third state is switched to the fourth state. The second heat transport medium heated at electromagnet101for magnetic refrigeration in the fourth state is delivered from electromagnet101for magnetic refrigeration to third heat exchanger111B by second pump113B. Concurrently, the second heat transport medium having absorbed heat of the external medium at fourth heat exchanger112B is delivered to electromagnet101for magnetic refrigeration. Subsequently, the fourth state is switched to the third state.

Electromagnet101for magnetic refrigeration basically having a configuration similar to that of electromagnet100for magnetic refrigeration can be as effective as electromagnet100for magnetic refrigeration.

Electromagnet100for magnetic refrigeration and the electromagnet for magnetic refrigeration according to the comparative example heat or cool a single heat transport medium, and applying electromagnet100for magnetic refrigeration and the electromagnet for magnetic refrigeration according to the comparative example each to a magnetic refrigerator comprising heat pumps of two systems requires two electromagnets100for magnetic refrigeration and two electromagnets for magnetic refrigeration according to the comparative example. In contrast, electromagnet101for magnetic refrigeration can heat or cool two heat transport media, and comprising a single electromagnet101for magnetic refrigeration suffices for magnetic refrigerator201comprising heat pumps of two systems. Thus, magnetic refrigerator201comprising a single electromagnet101for magnetic refrigeration can be smaller in size than a magnetic refrigerator comprising two electromagnets100for magnetic refrigeration or two electromagnets for magnetic refrigeration according to the comparative example.

Further, electromagnet101for magnetic refrigeration in magnetic refrigerator201comprising heat pumps of two systems can heat the first heat transport medium for one heat pump and concurrently cool the second heat transport medium for the other heat pump. Electromagnet101for magnetic refrigeration is thus higher in efficiency than electromagnet100for magnetic refrigeration.

Second Embodiment

As shown inFIG.13, an electromagnet102for magnetic refrigeration according to a second embodiment comprises a return yoke11, a fifth magnetic pole12, a sixth magnetic pole13, a seventh magnetic pole14, an eighth magnetic pole15, a centered magnetic pole16, a third coil18A, a fourth coil18B, a fifth coil19A, and a sixth coil19B.

As shown inFIG.13, return yoke11has a configuration similar to that of return yoke1shown inFIG.1. Return yoke11is in the form of a quadrangular ring for example. Return yoke11has a portion extending in the X direction and a portion extending in the Y direction orthogonal to the X direction. Each portion of return yoke11extends in the Z direction orthogonal to each of the X direction and the Y direction.

Fifth, sixth, seventh and eighth magnetic poles12,13,14and15, and centered magnetic pole16are disposed inside return yoke11. Fifth, sixth, seventh, and eighth magnetic poles12,13,14, and15are magnetically coupled to return yoke11.

Fifth magnetic pole12, centered magnetic pole16, and sixth magnetic pole13are aligned in the Y direction. Fifth magnetic pole12is spaced from centered magnetic pole16in the Y direction by a fifth gap17A. Sixth magnetic pole13is spaced from centered magnetic pole16in the Y direction by a sixth gap17B.

Seventh magnetic pole14, centered magnetic pole16, and eighth magnetic pole15are aligned in the X direction. Seventh magnetic pole14is spaced from centered magnetic pole16in the X direction by a seventh gap17C. Eighth magnetic pole15is spaced from centered magnetic pole16in the X direction by an eighth gap17D.

Centered magnetic pole16has a first surface16A extending in the X direction and facing fifth gap17A, a second surface16B extending in the X direction and facing sixth gap17B, a third surface16C extending in the Y direction and facing seventh gap17C, and a fourth surface16D extending in the Y direction and facing eighth gap17D. First, second, third, and fourth surfaces16A,16B,16C, and16D are, for example, a flat surface.

Fifth magnetic pole12has a flat surface extending in the X direction and facing fifth gap17A. Sixth magnetic pole13has a flat surface extending in the X direction and facing sixth gap17B. Seventh magnetic pole14has a flat surface extending in the Y direction and facing seventh gap17C. Eighth magnetic pole15has a flat surface extending in the Y direction and facing eighth gap17D.

Fifth, sixth, seventh and eighth magnetic poles12,13,14and15, and centered magnetic pole16are for example each equivalent in configuration. When viewed in the Z direction, fifth, sixth, seventh and eighth magnetic poles12,13,14and15, and centered magnetic pole16each have a planar shape for example in the form of a square.

As shown inFIG.13, when viewed in the Z direction, fifth and sixth gaps17A and17B each have a longitudinal direction in the X direction and a shorter-side direction in the Y direction. When viewed in the Z direction, seventh and eighth gaps17C and17D each have a longitudinal direction in the Y direction and a shorter-side direction in the X direction.

In electromagnet102for magnetic refrigeration, fifth magnetic pole12and centered magnetic pole16form a pair of opposite magnetic poles spaced by fifth gap17A, and sixth magnetic pole13and centered magnetic pole16form a pair of opposite magnetic poles spaced by sixth gap17B. Further, in electromagnet102for magnetic refrigeration, seventh magnetic pole14and centered magnetic pole16form a pair of opposite magnetic poles spaced by seventh gap17C, and eighth magnetic pole15and centered magnetic pole16form a pair of opposite magnetic poles spaced by eighth gap17D.

A spacing (or length) of fifth gap17A in first direction A is equal for example to a spacing (or length) of sixth gap17B in first direction A. A spacing (or length) of seventh gap17C in second direction B is equal for example to a spacing (or length) of eighth gap17D in second direction B.

The spacing of each of fifth, sixth, seventh, and eighth gaps17A,17B,17C, and17D is smaller, for example, than a width of each of third and fourth coils18A and18B in a direction along the central axis of each of third and fourth coils18A and18B (i.e., the Y direction), and a width of each of fifth and sixth coils19A and19B in a direction along the central axis of each of fifth and sixth coils19A and19B (i.e., the X direction).

Third coil18A surrounds fifth magnetic pole12in the X direction. Fourth coil18B surrounds sixth magnetic pole13in the X direction. Third and fourth coils18A and18B have their respective central axes extending in the Y direction.

Fifth coil19A surrounds seventh magnetic pole14in the Y direction. Sixth coil19B surrounds eighth magnetic pole15in the Y direction. Fifth and sixth coils19A and19B have their respective central axes extending in the X direction.

Third, fourth, fifth and sixth coils18A,18B,19A, and19B are each connected to a power source. Third, fourth, fifth and sixth coils18A,18B,19A and19B are concurrently energized or concurrently unenergized. In other words, the power source switches a fifth state in which third, fourth, and sixth coils18A,18B,19A, and19B are concurrently energized (seeFIG.14) to a sixth state in which third, fourth, fifth and sixth coils18A and18B,19A, and19B are concurrently unenergized (seeFIG.15), and vice versa.

When third and fourth coils18A and18B are energized, they generate a magnetic flux passing across fifth and sixth gaps17A and17B. When fifth and sixth coils19A and19B are energized, they generate a magnetic flux passing across seventh and eighth gaps17C and17D. When fifth, sixth, seventh and eighth magnetic poles12,13,14,15, and centered magnetic pole16are each unsaturated, the magnetic flux passing across fifth and sixth gaps17A and17B extends in the Y direction, and the magnetic flux passing across seventh and eighth gaps17C and17D extends in the X direction.

As shown inFIG.13, electromagnet102for magnetic refrigeration further comprises a fifth pipe20A, a sixth pipe20B, a seventh pipe20C, an eighth pipe20D, a fifth magnetocaloric member21, a sixth magnetocaloric member21B, a seventh magnetocaloric member21C, and an eight magnetocaloric member21D.

Fifth pipe20A is disposed in fifth gap17A. When viewed in the Z direction, fifth pipe20A has a longitudinal direction in the X direction and a shorter-side direction in the Y direction. Fifth pipe20A has an outer peripheral surface spaced for example from a surface of each of centered magnetic pole16and fifth magnetic pole12. Fifth pipe20A may have the outer peripheral surface for example in contact with the surface of each of centered magnetic pole16and fifth magnetic pole12. Inside fifth pipe20A is disposed fifth magnetocaloric member21A. Fifth magnetocaloric member21A is held inside fifth pipe20A.

Sixth pipe20B is disposed in sixth gap17B. When viewed in the Z direction, sixth pipe20B has a longitudinal direction in the X direction and a shorter-side direction in the Y direction. Sixth pipe20B has an outer peripheral surface spaced for example from a surface of each of centered magnetic pole16and sixth magnetic pole13. Sixth pipe20B may have the outer peripheral surface for example in contact with the surface of each of centered magnetic pole16and sixth magnetic pole13. Inside sixth pipe20B is disposed sixth magnetocaloric member21B. Sixth magnetocaloric member21B is held inside sixth pipe20B.

Seventh pipe20C is disposed in seventh gap17C. When viewed in the Z direction, seventh pipe20C has a longitudinal direction in the Y direction and a shorter-side direction in the X direction. Seventh pipe20C has an outer peripheral surface spaced for example from a surface of each of centered magnetic pole16and seventh magnetic pole14. Seventh pipe20C may have the outer peripheral surface for example in contact with the surface of each of centered magnetic pole16and seventh magnetic pole14. Inside seventh pipe20C is disposed seventh magnetocaloric member21C. Seventh magnetocaloric member2C is held inside seventh pipe20C.

Eighth pipe20D is disposed in eighth gap17D. When viewed in the Z direction, eighth pipe20D has a longitudinal direction in the Y direction and a shorter-side direction in the X direction. Eighth pipe20D has an outer peripheral surface spaced for example from a surface of each of centered magnetic pole16and eighth magnetic pole15. Eighth pipe20D may have the outer peripheral surface for example in contact with the surface of each of centered magnetic pole16and eighth magnetic pole15. Inside eighth pipe20D is disposed eighth magnetocaloric member21D. Eighth magnetocaloric member21D is held inside eighth pipe20D.

Fifth, sixth, seventh, and eighth pipes20A,20B,20C, and20D each extend in the Z direction. Fifth, sixth, seventh, and eighth pipes20A,20B,20C, and20D are each a straight pipe, for example. Fifth, sixth, seventh, and eighth pipes20A,20B,20C, and20D may each for example be a reciprocating pipe formed of a plurality of straight pipes connected in series by a U-shaped pipe.

When electromagnet100for magnetic refrigeration is incorporated in magnetic refrigerator200, fifth, sixth, seventh, and eighth pipes20A,20B,20C, and20D each have one and the other ends in the Z direction connected to an inflow/outflow pipe. When electromagnet100for magnetic refrigeration is incorporated in magnetic refrigerator200, fifth, sixth, seventh, and eighth pipes20A,20B,20C, and20D pass a heat transport medium therethrough. The heat transport medium passes through each of fifth, sixth, seventh, and eighth pipes20A,20B,20C, and20D in the Z direction.

A magnetic refrigerator according to the second embodiment is basically similar in configuration to magnetic refrigerator200according to the first embodiment except that the former differs from the latter in that the former comprises electromagnet102for magnetic refrigeration instead of electromagnet100for magnetic refrigeration.

In the magnetic refrigerator according to the second embodiment, electromagnet102for magnetic refrigeration has fifth, sixth, seventh, and eighth pipes20A,20B,20C, and20D connected to one another in parallel.

<Operation of Electromagnet for Magnetic Refrigeration>

InFIG.14, electromagnet102for magnetic refrigeration is in the fifth state. That is, inFIG.14, third, fourth, fifth and sixth coils18A,18B,19A, and19B are concurrently energized. InFIG.15, electromagnet102for magnetic refrigeration is in the sixth state. That is, inFIG.15, third, fourth, fifth and sixth coils18A,18B,19A, and19B are concurrently unenergized.

As shown inFIG.14, in the fifth state, third and fourth coils18A and18B create a magnetic flux passing across fifth and sixth gaps17A and17B (a thick solid line indicates a line of magnetic induction), and fifth and sixth coils19A and19B create a magnetic flux passing across seventh and eighth gaps17C and17D.

Thus, fifth, sixth, seventh, and eighth magnetocaloric members21A,21B,21C, and21D generate heat, and the heat transport medium passing through each of fifth, sixth, seventh, and eighth pipes20A,20B,20C, and20D is heated.

As shown inFIG.15, in the sixth state, no magnetic flux is formed across each of fifth, sixth, seventh, and eighth gaps17A,17B,17C, and17D. As a result, fifth, sixth, seventh, and eighth magnetocaloric members21A,21B,21C, and21D absorb heat, and the heat transport medium passing through each of fifth, sixth, seventh, and eighth pipes20A,20B,20C, and20D is cooled.

In the magnetic refrigerator according to the second embodiment, the fifth state shown inFIG.14and the sixth state shown inFIG.15are alternately and repeatedly switched. A pump performs the first operation in the fifth state and performs the second operation in the sixth state. In the fifth state, the heat transport medium heated at electromagnet102for magnetic refrigeration is delivered from electromagnet102for magnetic refrigeration to a first heat exchanger by the pump. Concurrently, the heat transport medium having absorbed heat of an external medium at a second heat exchanger is delivered to electromagnet102for magnetic refrigeration. Subsequently, the fifth state is switched to the sixth state. In the sixth state, the heat transport medium cooled at electromagnet102for magnetic refrigeration is delivered from electromagnet102for magnetic refrigeration to the second heat exchanger by the pump. Concurrently, the heat transport medium having dissipated heat at the first heat exchanger to the external medium is delivered to electromagnet102for magnetic refrigeration. Subsequently, the sixth state is switched to the fifth state.

In electromagnet102for magnetic refrigeration, a magnetic field generated in fifth gap17A between fifth magnetic pole12and centered magnetic pole16in the fifth state is stronger than a magnetic field generated inside an energized air core coil. Therefore, an amount of heat generated by fifth magnetocaloric member21A disposed in fifth gap17A in the fifth state is larger than an amount of heat generated by a magnetocaloric member disposed inside the energized air core coil. A difference in temperature of the fifth magnetocaloric member21A between the firth state and the sixth state is larger than a difference in temperature of the magnetocaloric member disposed inside the energized air core coil therebetween. Sixth, seventh and eighth magnetocaloric members21B,21C and21D are also similar to fifth magnetocaloric member21A. As a result, an endothermic/exothermic effect of each of fifth, sixth, seventh, and eighth magnetocaloric members21A,21B,21C, and21D in electromagnet102for magnetic refrigeration is larger than that when a magnetocaloric member is disposed inside an air core coil.

Modified Example

FIGS.16and17are diagrams showing an electromagnet103for magnetic refrigeration that is a modified example of electromagnet102for magnetic refrigeration.

In electromagnet103for magnetic refrigeration, third and fourth coils18A and18B and fifth and sixth coils19A and19B are alternately energized. In other words, the power source switches a seventh state in which third and fourth coils18A and18B are energized and fifth and sixth coils19A and19B are unenergized (seeFIG.16) to an eighth state in which third and fourth coils18A and18B are unenergized and fifth and sixth coils19A and19B are energized (seeFIG.17), and vice versa.

InFIG.16, electromagnet103for magnetic refrigeration is in the seventh state. That is, inFIG.16, third and fourth coils18A and18B are energized, and fifth and sixth coils19A and19B are unenergized. InFIG.17, electromagnet103for magnetic refrigeration is in the eighth state. That is, inFIG.17, third and fourth coils18A and18B are unenergized, and fifth and sixth coils19A and19B are energized.

As shown inFIG.16, in the seventh state, third and fourth coils18A and18B create a magnetic flux passing across fifth and sixth gaps17A and17B (a thick solid line indicates a line of magnetic induction). As a result, fifth and sixth magnetocaloric members21A and21B generate heat, and the heat transport medium passing through fifth and sixth pipes20A and20B is heated. In the seventh state, no magnetic flux is formed across seventh and eighth gaps17C and17D. As a result, seventh and eighth magnetocaloric members21C and21D absorb heat, and the heat transport medium passing through seventh and eighth pipes20C and20D is cooled.

As shown inFIG.17, in the eighth state, fifth and sixth coils19A and19B create a magnetic flux passing across seventh and eighth gaps17C and17D. As a result, seventh and eighth magnetocaloric members21C and21D generate heat, and the heat transport medium passing through seventh and eighth pipes20C and20D is heated. In the eighth state, no magnetic flux is formed across fifth and sixth gaps17A and17B. As a result, fifth and sixth magnetocaloric members21A and21B absorb heat, and the heat transport medium passing through fifth and sixth pipes20A and20B is cooled.

A magnetic refrigerator comprising electromagnet103for magnetic refrigeration shown inFIGS.16and17is basically similar in configuration to magnetic refrigerator201comprising electromagnet101for magnetic refrigeration shown inFIGS.11and12, except that the former differs from the latter in that the former comprises electromagnet103for magnetic refrigeration instead of electromagnet101for magnetic refrigeration.

The magnetic refrigerator comprising electromagnet103for magnetic refrigeration comprises a heat pump of a first system and a heat pump of a second system. The heat pump of the first system is independent of the heat pump of the second system.

The heat pump of the first system includes fifth and sixth pipes20A and20B of electromagnet103for magnetic refrigeration, a first heat exchanger, a second heat exchanger, and a pump. The heat pump of the first system does not include seventh and eighth pipes20C and20D of electromagnet103for magnetic refrigeration.

The heat pump of the first system has fifth and sixth pipes20A and20B connected to each other in parallel. The first heat transport medium is split into fifth and sixth pipes20A and20B in electromagnet103for magnetic refrigeration. In the heat pump of the first system, the pump performs the first operation when electromagnet103for magnetic refrigeration is in the seventh state, and the pump performs the second operation when electromagnet103for magnetic refrigeration is in the eighth state. Electromagnet103for magnetic refrigeration alternately repeats the seventh state and the eighth state. The pump alternately repeats the first operation and the second operation.

The first heat transport medium heated at electromagnet103for magnetic refrigeration in the seventh state is delivered from electromagnet103for magnetic refrigeration to the first heat exchanger by the pump. Concurrently, the first heat transport medium having absorbed heat of an external medium at the second heat exchanger is delivered to electromagnet103for magnetic refrigeration. Subsequently, the seventh state is switched to the eighth state. The first heat transport medium cooled at electromagnet103for magnetic refrigeration in the eighth state is delivered from electromagnet103for magnetic refrigeration to the second heat exchanger by the pump. Concurrently, the first heat transport medium having dissipated heat at the first heat exchanger to the external medium is delivered to electromagnet103for magnetic refrigeration. Subsequently, the eighth state is switched to the seventh state.

The heat pump of the second system includes seventh and eighth pipes20C and20D of electromagnet103for magnetic refrigeration, a third heat exchanger, a fourth heat exchanger, and a pump. The heat pump of the second system does not include fifth and sixth pipes20A and20B. The heat pump of the second system has seventh and eighth pipes20C and20D connected to each other in parallel. In the heat pump of the second system, the second pump performs the first operation when electromagnet103for magnetic refrigeration is in the eighth state, and the second pump performs the second operation when electromagnet103for magnetic refrigeration is in the seventh state.

The second heat transport medium cooled at electromagnet103for magnetic refrigeration in the seventh state is delivered from electromagnet103for magnetic refrigeration to the fourth heat exchanger by the second pump. Concurrently, the second heat transport medium having dissipated heat at the third heat exchanger to the external medium is delivered to electromagnet103for magnetic refrigeration. Subsequently, the seventh state is switched to the eighth state. The second heat transport medium heated at electromagnet103for magnetic refrigeration in the eighth state is delivered from electromagnet103for magnetic refrigeration to the third heat exchanger by the second pump. Concurrently, the second heat transport medium having absorbed heat of the external medium at the fourth heat exchanger is delivered to electromagnet103for magnetic refrigeration. Subsequently, the eighth state is switched to the seventh state.

Electromagnet103for magnetic refrigeration basically having a configuration similar to that of electromagnet102for magnetic refrigeration can be as effective as electromagnet102for magnetic refrigeration.

Further, for a ground similar to that for magnetic refrigerator201comprising electromagnet101for magnetic refrigeration, the magnetic refrigerator comprising electromagnet103for magnetic refrigeration can be smaller in size than the magnetic refrigerator comprising two electromagnets102for magnetic refrigeration or two electromagnets for magnetic refrigeration according to the comparative example.

Further, electromagnet103for magnetic refrigeration in the magnetic refrigerator can heat the first heat transport medium of one heat pump and concurrently cool the second heat transport medium of the other heat pump. Electromagnet103for magnetic refrigeration is thus higher in efficiency than electromagnet102for magnetic refrigeration.

Third Embodiment

As shown inFIGS.18to20, an electromagnet104for magnetic refrigeration according to a third embodiment is basically similar in configuration to electromagnet102for magnetic refrigeration according to the second embodiment, except that the former differs from the latter in that the former has centered magnetic pole16rotated by 45 degrees with respect to a central axis extending in the Z direction.

Note thatFIGS.18to20indicate a fifth direction C and a sixth direction D inclined with respect to the X direction (a fourth direction) and the Y direction (a third direction). Fifth direction C intersects sixth direction D, and is orthogonal to sixth direction D, for example. While fifth direction C may be inclined with respect to the X direction and the Y direction at any angle, the angle is preferably 45 degrees when viewed in the Z direction in view of suppressing saturation of each of fifth, sixth, seventh, and eighth magnetic poles12,13,14, and15.

From a different viewpoint, centered magnetic pole16has a fifth surface16E, a sixth surface16F, a seventh surface16G, and an eighth surface16H instead of first, second, third, and fourth surfaces16A,16B,16C, and16D shown inFIG.13.

Fifth surface16E extends in fifth direction C. Fifth surface16E faces a portion of fifth gap17A and a portion of seventh gap17C.

Sixth surface16F extends in fifth direction C. Sixth surface16F faces a portion of sixth gap17B and a portion of eighth gap17D.

Seventh surface16G extends in sixth direction D. Seventh surface160faces each of a remainder of sixth gap17B and a remainder of seventh gap17C.

Eighth surface16H extends in sixth direction D. Eighth surface16H faces each of a remainder of fifth gap17A and a remainder of eighth gap17D.

One end of fifth surface16E in fifth direction C is connected to one end of seventh surface160in sixth direction D, and the other end of fifth surface16E in fifth direction C is connected to one end of eighth surface16H in sixth direction D. One end of sixth surface16F in fifth direction C is connected to the other end of seventh surface160in sixth direction D, and the other end of sixth surface16F in fifth direction C is connected to the other end of eighth surface16H in sixth direction D.

When viewed in the Z direction, fifth, sixth, seventh and eighth magnetic poles12,13,14and15each have a planar shape with a recess. Fifth, sixth, seventh, and eighth magnetic poles12,13,14, and15each have a flat surface extending in fifth direction C and a flat surface extending in sixth direction D.

Fifth gap17A provides spacing between the flat surface of fifth magnetic pole12extending in fifth direction C and fifth surface16E of centered magnetic pole16and between the flat surface of fifth magnetic pole12extending in sixth direction D and eighth surface16H of centered magnetic pole16.

Sixth gap17B provides spacing between the flat surface of sixth magnetic pole13extending in fifth direction C and sixth surface16F of centered magnetic pole16, and between the flat surface of sixth magnetic pole13extending in sixth direction D and seventh surface16G of centered magnetic pole16.

Seventh gap17C provides spacing between the flat surface of seventh magnetic pole14extending in fifth direction C and fifth surface16E of centered magnetic pole16and between the flat surface of seventh magnetic pole14extending in sixth direction D and seventh surface16G of centered magnetic pole16.

Eighth gap17D provides spacing between the flat surface of eighth magnetic pole15extending in fifth direction C and sixth surface16F of centered magnetic pole16and between the flat surface of eighth magnetic pole15extending in sixth direction D and eighth surface16H of centered magnetic pole16.

Electromagnet104for magnetic refrigeration can be driven in a manner similar to that in which electromagnet102for magnetic refrigeration is driven. Specifically, electromagnet104for magnetic refrigeration repeats the seventh state shown inFIG.19and the eighth state shown inFIG.20. In this case, electromagnet104for magnetic refrigeration can be as effective as electromagnet102for magnetic refrigeration. Further, electromagnet104for magnetic refrigeration can also be driven in a manner similar to that in which electromagnet103for magnetic refrigeration is driven. In this case, electromagnet104for magnetic refrigeration can be as effective as electromagnet102for magnetic refrigeration.

Further, a length of fifth gap17A in the longitudinal direction for electromagnet104for magnetic refrigeration is longer than a length of fifth gap17A in the longitudinal direction for each of electromagnets102and103for magnetic refrigeration, and the former is, for example, √2 times the latter. Thus, an endothermic/exothermic effect of each of fifth, sixth, seventh, and eighth magnetocaloric members21A,21B,21C, and21D in electromagnet104for magnetic refrigeration is larger than that in electromagnets102and103for magnetic refrigeration.

Fourth Embodiment

As shown inFIG.21, an electromagnet105for magnetic refrigeration according to a fourth embodiment comprises a return yoke22A, a ninth magnetic pole22B, a tenth magnetic pole22C, a seventh coil24A, and an eighth coil24B.

Return yoke22A is formed with ninth and tenth magnetic poles22B and22C in one piece. When viewed in the Z direction, return yoke21has a planar shape for example in the form of a letter C. Return yoke22A has a portion extending in the X direction and a portion extending in the Y direction orthogonal to the X direction. Each portion of return yoke22A extends in the Z direction orthogonal to each of the X direction and the Y direction. Note thatFIG.21indicates a seventh direction E and an eighth direction F inclined with respect to the X direction and the Y direction. Seventh direction E intersects eighth direction F, and is orthogonal to eighth direction F, for example. While seventh direction E may be inclined with respect to the X direction and the Y direction at any angle, the angle is preferably 45 degrees in view of suppressing saturation of each of ninth and tenth magnetic poles22B and22C.

Ninth magnetic pole22B is connected to one end of return yoke22A. Tenth magnetic pole22C is connected to the other end of return yoke22A. Ninth magnetic pole22B is spaced from tenth magnetic pole22C by ninth gap23. Ninth and tenth magnetic poles22B and22C each have a surface extending in seventh direction E.

Seventh coil24A surrounds ninth magnetic pole22B in the X direction. Eighth coil24B surrounds tenth magnetic pole22C in the X direction. Seventh and eighth coils24A and24B have their respective central axes extending in the Y direction.

Seventh and eighth coils24A and24B are each connected to a power source (power source114inFIG.3). Seventh and eighth coils24A and24B are concurrently energized or concurrently unenergized. In other words, the power source switches a state in which seventh and eighth coils24A and24B are concurrently energized to a state in which seventh and eighth coils24A and24B are concurrently unenergized, and vice versa.

Ninth gap23faces ninth magnetic pole22B at a surface extending in seventh direction E and faces tenth magnetic pole22C at surface extending in seventh direction E. As shown inFIG.21, when viewed in the Z direction, ninth gap23has a longitudinal direction in seventh direction E and a shorter-side direction in eighth direction F.

As shown inFIG.21, electromagnet105for magnetic refrigeration further comprises a ninth pipe25and a ninth magnetocaloric member26.

Ninth pipe25is disposed in ninth gap23. When viewed in the Z direction, ninth pipe25has a longitudinal direction in seventh direction E and a shorter-side direction in eighth direction F. Ninth pipe25has an outer peripheral surface spaced for example from a surface of each of ninth and tenth magnetic poles22B and22C. Ninth pipe25may have the outer peripheral surface for example in contact with the surface of each of ninth and tenth magnetic poles22B and22C. Inside ninth pipe25is disposed ninth magnetocaloric member26. Ninth magnetocaloric member26is held inside ninth pipe25.

Ninth magnetocaloric member26is similar in configuration to first magnetocaloric member10A. Such an electromagnet105for magnetic refrigeration can also be as effective as electromagnet100for magnetic refrigeration.

In other words, an endothermic/exothermic effect of ninth magnetocaloric member26in electromagnet105for magnetic refrigeration is larger than that when a magnetocaloric member is disposed inside an air core coil.

Further, electromagnet105for magnetic refrigeration has ninth and tenth magnetic poles22B and22C each facing ninth gap23in an area which is √2 times such an area for the electromagnet for magnetic refrigeration according to the comparative example described above, and electromagnet105for magnetic refrigeration passes inside ninth gap23a magnetic flux that is √2 times that passing inside a gap of the comparative example. As a result, an endothermic/exothermic effect of ninth magnetocaloric member26in electromagnet105for magnetic refrigeration is larger than that in the electromagnet for magnetic refrigeration according to the comparative example.

Modified Example

FIG.22is a diagram showing an electromagnet106for magnetic refrigeration that is a modified example of electromagnet105for magnetic refrigeration. Electromagnet106for magnetic refrigeration is basically similar in configuration to electromagnet105for magnetic refrigeration, except that the former differs from the latter in that the former comprises ninth and tenth magnetic poles22B and22C each having a surface extending in seventh direction E and a surface extending in eighth direction F.

When viewed in the Z direction, ninth magnetic pole22B is formed, for example, in a recessed shape. When viewed in the Z direction, tenth magnetic pole22C is formed, for example, in a projecting shape.

Ninth gap23has a first region facing a surface of ninth magnetic pole22B extending in seventh direction E and a surface of tenth magnetic pole22C extending in seventh direction E, and a second region facing a surface of ninth magnetic pole22B extending in eighth direction F and a surface of tenth magnetic pole22C extending in eighth direction F. As shown inFIG.22, when viewed in the Z direction, the first region of ninth gap23has a longitudinal direction in seventh direction E and a shorter-side direction in eighth direction F. When viewed in the Z direction, the second region of ninth gap23has a longitudinal direction in eighth direction F and a shorter-side direction in seventh direction E.

Electromagnet106thus provided for magnetic refrigeration can also be as effective as electromagnet105for magnetic refrigeration.

Fifth Embodiment

As shown inFIG.23, an electromagnet107for magnetic refrigeration according to a fifth embodiment is basically similar in configuration to electromagnet106for magnetic refrigeration according to the fourth embodiment, except that the former differs from the latter in that the former further comprises an eleventh magnetic pole27.

Eleventh magnetic pole27is disposed between ninth and tenth magnetic poles22B and22C in the Y direction. Eleventh magnetic pole27is spaced from ninth magnetic pole22B in the Y direction by ninth gap23A, and spaced from tenth magnetic pole22C in the Y direction by tenth gap23B.

Electromagnet107for magnetic refrigeration basically having a configuration similar to that of electromagnet106for magnetic refrigeration can be as effective as electromagnet106for magnetic refrigeration. Note that while electromagnet107for magnetic refrigeration has a number of gaps which is twice that for electromagnet106for magnetic refrigeration and hence requires magnetomotive force which is twice that for electromagnet106for magnetic refrigeration, the former can also have a number of magnetocaloric members which is twice that for the latter. Thus, electromagnet107for magnetic refrigeration can generally have an endothermic/exothermic effect equivalent to that of electromagnet106for magnetic refrigeration.

Sixth Embodiment

As shown inFIG.24, an electromagnet108for magnetic refrigeration according to a sixth embodiment is basically similar in configuration to electromagnet102for magnetic refrigeration according to the second embodiment, except that the former differs from the latter in that the former comprises a return yoke31in the form of a hexagonal ring.

Electromagnet108for magnetic refrigeration comprises return yoke31, six magnetic poles32to37, a centered magnetic pole38, and six coils39to44.

Six magnetic poles32to37are each disposed inside return yoke31. Six magnetic poles32to37are magnetically coupled to return yoke31.

As shown inFIG.24, six magnetic poles32to37are each spaced from centered magnetic pole38by a gap. Magnetic poles32and33are disposed so as to sandwich centered magnetic pole38. Magnetic poles34and35are disposed so as to sandwich centered magnetic pole38. Magnetic poles36and37are disposed so as to sandwich centered magnetic pole38.

For electromagnet108for magnetic refrigeration, each of six magnetic poles32to37and centered magnetic pole38form a pair of opposite magnetic poles spaced by one of six gaps. That is, electromagnet108for magnetic refrigeration has six pairs of opposite magnetic poles. When viewed in the Z direction, six magnetic poles32to37each have a planar shape for example in the form of a square. When viewed in the Z direction, centered magnetic pole38has a planar shape in the form of a hexagon.

Six coils39to44each surround one of six magnetic poles32to37. Six coils39to44may be divided into three pairs of coils based on the directions in which their respective central axes extend. Coils39and40of a first pair have their respective axes extending in the Y direction. Coils41and42of a second pair have their respective axes extending in a direction inclined by 30 degrees with respect to the Y direction. Coils43and44of a third pair have their respective axes extending in a direction inclined by 60 degrees with respect to the Y direction.

Six coils39to44are each connected to a power source (power source114inFIG.3). Six coils39to44are, for example, concurrently energized or concurrently unenergized. In other words, the power source switches a ninth state in which six coils39to44are each energized concurrently (seeFIG.25) to a tenth state in which six coils39to44are each unenergized concurrently (seeFIG.26), and vise versa.

In each of the six gaps are disposed a pipe extending in the Z direction and a magnetocaloric member disposed inside the pipe.

While such an electromagnet108for magnetic refrigeration can be as effective as electromagnet102for magnetic refrigeration, the former has a larger number of magnetocaloric members than the latter, and hence generally has an endothermic/exothermic effect larger than the latter.

Electromagnet108for magnetic refrigeration may be driven in a manner similar to that in which electromagnet102for magnetic refrigeration shown inFIGS.14and15is driven. For example, three states in which the coils of only one of the three pairs of coils are energized concurrently and the coils of the other two pairs are unenergized concurrently may be switched. Further, a state in which the coils of only two of the three pairs of coils are energized concurrently and the coils of the other one pair are unenergized concurrently, and a state in which the coils of only the other one pair are energized concurrently and the coils of the other two pairs are unenergized concurrently may be switched.

Electromagnets100,101and103-107for magnetic refrigeration may also have their return yokes in the form of a hexagonal ring when viewed in the Z direction.

While embodiments of the present disclosure have been described above, the above-described embodiments can be modified variously. Further, the scope of the present disclosure is not limited to the above-described embodiments. The scope of the present disclosure is defined by the terms of the claims, and is intended to include any modifications within the meaning and scope equivalent to the terms of the claims.

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