Magnetic field generating device and magnetic refrigeration device using the same

Abstract

To provide a magnetic field generator capable of generating a high magnetic field with a small amount of permanent magnets.SOLUTION: A magnetic field generating device is provided, having a pair of magnetic field generating members 10 and 20 arranged opposite to each other with a spatial gap in between, each of the magnetic field generating members 10 and 20 is composed of a soft magnetic material and a permanent magnet, each of the magnetic field generating members 10 and 20 includes a first magnetic pole portion and a second magnetic pole portion that generate a magnetic field in the spatial gap 50, and there are N magnetic flux routes (N≥2) in which magnetic flux flows from the second magnetic pole portion to the first magnetic pole portion through the magnetic field generating member, and the N magnetic flux routes include first magnetic flux routes 15, 16 and a second magnetic flux route 14 on a different plane from the first magnetic flux route.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a magnetic field generating device and a magnetic refrigeration device using the same. [Background technology]

[0002] Vapor compression refrigeration freezers that use refrigerant gases such as alternatives to chlorofluorocarbons are widely used in air conditioners and refrigerators, but magnetic refrigeration is a different cooling technology that does not use refrigerant gases.

[0003] Magnetic refrigeration utilizes the magnetocaloric effect, whereby a ferromagnetic material generates heat when a magnetic field is applied (excited) in an adiabatic state, and absorbs heat when the magnetic field is removed (demagnetized). In magnetic refrigeration systems, the ferromagnetic material used to utilize the magnetocaloric effect is called a magnetic working material. In magnetic refrigeration systems that operate at room temperature, a high magnetic field is applied and removed periodically to the magnetic working material, and at the same time, a heat exchange liquid such as water is passed through a container filled with the magnetic working material to exchange heat and transport it, thereby realizing a heat pump.

[0004] Known examples of magnetic refrigeration devices that operate in the room temperature range include magnetic circuits using permanent magnets to reduce power consumption and form a magnetic field generator. For example, Patent Document 1 (Patent Document 1) discloses a magnetic circuit with a Halbach array of permanent magnets arranged in a circular ring shape in Figures 3 and 4. Patent Document 1 also describes a doughnut-shaped arrangement of multiple permanent magnets with different magnetization directions, which are arranged in pairs to generate a high magnetic field only in a portion of the gap between them. A duct filled with a magnetically active material is placed in the gap, and the magnetically active material is magnetized and demagnetized by rotating the pair of circular Halbach arrays. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-226735 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the technology disclosed in Patent Document 1, all components of the permanent magnet magnetic circuit in a Halbach array arranged in a circular ring are made up of permanent magnets, and if neodymium magnets are used as the permanent magnet material to obtain a practically sufficient magnetic field (typical magnetic flux density of 1 T or more), there is a problem that the price of the device increases.

[0007] The problem to be solved by the present invention is to provide a magnetic field generator capable of generating a strong magnetic field with a small amount of permanent magnets, and a magnetic refrigerator using the same. [Means for solving the problem]

[0008] The magnetic field generating device of the present invention is, for example, a magnetic field generating device having a pair of magnetic field generating members arranged opposite to each other with a spatial gap therebetween, the magnetic field generating members being composed of a soft magnetic material and a permanent magnet, each of the magnetic field generating members having a first magnetic pole portion and a second magnetic pole portion that generate a magnetic field in the spatial gap, and there are N (N≧2) magnetic flux routes through which magnetic flux flows from the second magnetic pole portion to the first magnetic pole portion through the magnetic field generating member, and the N magnetic flux routes are Passing the First York a first magnetic flux route; Passing through a second yoke different from the first yoke and a second magnetic flux route on a different plane from the first magnetic flux route. and each of the first magnetic pole portion and the second magnetic pole portion has at least N permanent magnets arranged around a core of a soft magnetic material, the permanent magnet of the first magnetic pole portion is magnetized in a direction that magnetizes the core of the soft magnetic material to a first polarity, and the permanent magnet of the second magnetic pole portion is magnetized in a direction that magnetizes the core of the soft magnetic material to a second polarity, the first magnetic pole portion of one of the pair of magnetic field generating members faces the second magnetic pole portion of the other of the pair of magnetic field generating members across the spatial gap, the second magnetic pole portion of one of the pair of magnetic field generating members faces the first magnetic pole portion of the other of the pair of magnetic field generating members, and the first magnetic flux route and the second magnetic flux route enter the core of the soft magnetic material from different faces of the core of the soft magnetic material. It is characterized by:

[0009] Furthermore, the magnetic refrigeration device of the present invention is, for example, a magnetic refrigeration device using the above-mentioned magnetic field generating device, and is equipped with a rotation mechanism that rotates the magnetic field generating device, a flat-plate-shaped filled container placed in the spatial gap sandwiched between the pair of magnetic field generating members of the magnetic field generating device, a pump that circulates a heat exchange fluid, a cold head that is cooled by the heat exchange fluid, a heat rejection heat exchanger that rejects heat from the heat exchange fluid, and a movable valve that controls the flow of the heat exchange fluid in conjunction with the movement of the rotation mechanism, wherein the magnetic field generating device rotates in the in-plane direction of the flat-plate-shaped filled container, the filled container is filled with a magnetic working material, the filled container, the pump, the cold head, the heat rejection heat exchanger, and the movable valve are connected by piping to form a circulation path through which the heat exchange fluid circulates, and the cold head is cooled by the magnetic field generated by the magnetic field generating device and the magnetocaloric effect of the magnetic working material. [Effects of the Invention]

[0010] According to the present invention, the magnetic field generating member is composed of a soft magnetic material and a permanent magnet, so the amount of permanent magnet can be reduced and the magnetic flux route can be made three-dimensional, which increases the magnetic flux and enables the generation of a strong magnetic field.As a result, a magnetic field generating device that can generate a strong magnetic field with a small amount of permanent magnets and a magnetic refrigeration device using the same can be realized. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a perspective view of a magnetic field generating device according to a first embodiment. [Figure 2] FIG. 2 is a perspective view schematically showing the magnetization direction and magnetic flux route in the magnetic field generating device of the first embodiment. [Figure 3] FIG. 2 is a perspective view of a lower magnetic field generating member in the magnetic field generating device of the first embodiment. [Figure 4] 2 is a cross-sectional view schematically showing the magnetization direction and magnetic flux route in the magnetic field generating device of the first embodiment. FIG. [Figure 5] FIG. 10 is a perspective view schematically showing a magnetic refrigeration device according to a second embodiment. [Figure 6] FIG. 10 is a schematic diagram showing a container filled with a magnetic working material in a second embodiment. [Figure 7] FIG. 10 is a diagram schematically illustrating a circulation flow path in a magnetic refrigeration apparatus according to a second embodiment. [Figure 8] FIG. 10 is a perspective view of a magnetic field generating device according to a third embodiment. [Figure 9] FIG. 10 is a perspective view schematically showing the magnetization direction and magnetic flux route in a magnetic field generating device according to a third embodiment. [Figure 10A] FIG. 10 is a cross-sectional view schematically showing the magnetization direction and magnetic flux route in a magnetic field generating device according to a third embodiment. [Figure 10B] FIG. 11 is a top view of a lower magnetic field generating member in a magnetic field generating device according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] The following describes in detail the embodiments of the present disclosure, but the disclosure of each embodiment is not limited to the description of the embodiment, and configurations in which the elemental technologies disclosed or suggested in each embodiment are appropriately combined within the scope of the knowledge of a person skilled in the art are also included in the scope of the present embodiment. Furthermore, in each drawing and each embodiment, the same or similar components are denoted by the same reference numerals, and redundant explanations are omitted.

[0013] [First embodiment] The first embodiment proposes a configuration of a magnetic field generating device in which the number of magnetic flux routes of the magnetic field generating member is N=3.

[0014] 1 shows a perspective view of a magnetic field generating device 100 according to a first embodiment. The magnetic field generating device 100 includes a pair of magnetic field generating members arranged opposite each other above and below (in the Z-axis direction) with a spatial gap 50 therebetween. The pair of magnetic field generating members is composed of an upper magnetic field generating member 10 and a lower magnetic field generating member 20.

[0015] As an example, the lower magnetic field generating member 20 is described. The lower magnetic field generating member 20 is composed of a soft magnetic material and a permanent magnet. The lower magnetic field generating member 20 has two soft magnetic cores 3-F and 4-F. Five permanent magnets, 3-A, 3-B, 3-C, 3-D, and 3-E, are arranged around the soft magnetic core 3-F. Similarly, five permanent magnets, 4-A, 4-B, 4-C (hidden and not shown), 4-D, and 4-E, are arranged around the soft magnetic core 4-F. To allow magnetic flux to flow between the soft magnetic cores 3-F and 4-F, yokes 21, 22, and 23 made of soft magnetic material are arranged. The yoke 21 is connected to the permanent magnets 3-A and 4-A, the yoke 22 is connected to the permanent magnets 3-B and 4-B, and the yoke 23 is connected to the permanent magnets 3-C and 4-C (hidden and not shown). The upper magnetic field generating member 10 also has a similar configuration to the lower magnetic field generating member 20 described above.

[0016] The magnetic field generating device 100 of the first embodiment has four main magnetic pole sections when viewed as a magnetic circuit. The first magnetic pole section is composed of permanent magnets 1-A, 1-B, 1-C, 1-D, and 1-E and a soft magnetic core 1-F (hidden and not shown), the second magnetic pole section is composed of permanent magnets 2-A, 2-B, 2-C, 2-D, and 2-E and a soft magnetic core 2-F (hidden and not shown), the third magnetic pole section is composed of permanent magnets 3-A, 3-B, 3-C, 3-D, and 3-E and a soft magnetic core 3-F, and the fourth magnetic pole section is composed of permanent magnets 4-A, 4-B, 4-C (hidden and not shown), 4-D, and 4-E and a soft magnetic core 4-F. The mechanism for generating a magnetic field from the magnetic pole portion will be described later, but in the magnetic field generating device 100 of this embodiment, a magnetic field in the -Z direction is generated in the region of the spatial gap 50 sandwiched between the first magnetic pole portion and the third magnetic pole portion, and a magnetic field in the +Z direction is generated in the region of the spatial gap 50 sandwiched between the second magnetic pole portion and the fourth magnetic pole portion.

[0017] To explain the flow of magnetic flux generated in the magnetic field generator 100 of the first embodiment, FIG. 2 schematically shows the magnetization direction of the permanent magnet and the routes (magnetic flux routes) along which the magnetic flux flows within the magnetic field generating member. The solid arrows drawn on the permanent magnets in the figure indicate the magnetization direction of the permanent magnets. In the upper magnetic field generating member 10, there are three magnetic flux routes 14, 15, and 16 (dotted arrows) that run from the second magnetic pole portion to the first magnetic pole portion. The magnetic flux route 15 and the magnetic flux route 16 are on the same plane (the XY plane), while the magnetic flux route 14 is on a different plane (the YZ plane). Similar to the upper magnetic field generating member 10, the lower magnetic field generating member 20 also has three magnetic flux routes 24, 25, and 26 (hidden and not shown) that run from the third magnetic pole portion to the fourth magnetic pole portion. Considering the direction of the magnetic flux route, the third magnetic pole portion corresponds to the second magnetic pole portion, and the fourth magnetic pole portion corresponds to the first magnetic pole portion.

[0018] To more clearly explain the relationship between the components and the magnetic flux routes in each magnetic field generating member, Figure 3 shows a perspective view of the lower magnetic field generating member 20, depicting the magnetization direction and magnetic flux routes of the permanent magnets. Note that the solid arrows drawn on the permanent magnets in the figure indicate the magnetization direction of the permanent magnets. Permanent magnets 3-A, 3-B, and 3-C that make up the third magnetic pole section are connected to permanent magnets 4-A, 4-B, and 4-C that make up the fourth magnetic pole section via yokes 21, 22, and 23, respectively, generating magnetic flux routes 24, 25, and 26 within each yoke. The magnetic flux flowing through each magnetic flux route is concentrated in soft magnetic core 4-F, generating a magnetic field in the +Z direction.

[0019] To explain the overall operation of the magnetic circuit of this embodiment, FIG. 4 shows a cross-sectional view schematically illustrating the magnetization direction and magnetic flux route. FIG. 4 is a cross-sectional view of the YZ plane cut at the center (point P) of the X-direction thickness of the yoke 11 in FIGS. 1 to 3 . The solid arrows drawn on the permanent magnets in the figure indicate the magnetization direction of the permanent magnets. The magnetic flux concentrated in the soft magnetic core 1-F constituting the first magnetic pole portion of the upper magnetic field generating member 10 flows to the soft magnetic core 3-F constituting the third magnetic pole portion of the lower magnetic field generating member 20, generating a magnetic field in the -Z direction in the spatial gap 50 between the soft magnetic cores 1-F and 3-F. The magnetic flux flowing in the soft magnetic core 3-F passes through the magnetic flux routes 24, 25 (not shown), and 26 of the yokes 21, 22 (not shown), and 23 (located deeper than the cross section) and is concentrated in the soft magnetic core 4-F constituting the fourth magnetic pole portion. The concentrated magnetic flux flows into soft magnetic core 2-F, which constitutes the second magnetic pole portion of upper magnetic field generating member 10, and generates a magnetic field in the +Z direction in the region of space gap 50 sandwiched between soft magnetic core 4-F and soft magnetic core 2-F. The magnetic flux flowing into soft magnetic core 2-F passes through magnetic flux routes 14, 15 (not shown), and 16 of yokes 11, 12 (not shown), and 13 (located in the depth direction from the cross section) and is concentrated in soft magnetic core 1-F. With the above mechanism, in this embodiment, it is possible to generate a magnetic field in the Z direction in a specific region of space gap 50.

[0020] In addition, permanent magnets 1-D, 1-E, 2-D, 2-E, 3-D, 3-E, 4-D, and 4-E adjacent to the soft magnetic core in the Y direction act to confine the magnetic flux that tends to spread in the ±Y-axis directions within the space gap 50, and these permanent magnets also effectively work to increase the magnetic field strength within the space gap 50.

[0021] To summarize the above configuration, the magnetic field generator 100 has a pair of magnetic field generating members arranged opposite each other with a spatial gap 50 between them, the magnetic field generating members being composed of a soft magnetic material and a permanent magnet, each of the magnetic field generating members having a first magnetic pole portion and a second magnetic pole portion that generate a magnetic field in the spatial gap 50, and there are N (here, N=3) magnetic flux routes through the magnetic field generating member along which magnetic flux flows from the second magnetic pole portion to the first magnetic pole portion, the N magnetic flux routes including first magnetic flux routes 15, 16 (or 25, 26) and a second magnetic flux route 14 (or 24) on a plane different from the first magnetic flux routes 15, 16 (or 25, 26). Note that in the lower magnetic field generating member 20, the third magnetic pole portion corresponds to the second magnetic pole portion, and the fourth magnetic pole portion corresponds to the first magnetic pole portion, and therefore are collectively referred to here as the first magnetic pole portion and the second magnetic pole portion.

[0022] According to this configuration, the magnetic field generating member is composed of a soft magnetic material and a permanent magnet, so the amount of permanent magnets can be reduced compared to a conventional Halbach array permanent magnet magnetic circuit in which all permanent magnets are arranged in a circular ring shape, and since the magnetic flux routes 14, 24 are on different planes, the magnetic flux routes can be made three-dimensional. Therefore, compared to a conventional Halbach array permanent magnet magnetic circuit in which all magnetic flux routes are arranged in a circular ring shape on the same plane, the magnetic flux increases and a strong magnetic field can be generated. Therefore, a magnetic field generating device that can generate a strong magnetic field with a small amount of permanent magnets can be realized.

[0023] More specifically, each of the first magnetic pole portion and the second magnetic pole portion has at least N permanent magnets arranged around a soft magnetic core, with the permanent magnets in the first magnetic pole portion magnetized in a direction that magnetizes the soft magnetic core to a first polarity, and the permanent magnets in the second magnetic pole portion magnetized in a direction that magnetizes the soft magnetic core to a second polarity. While permanent magnets may be used for the core, using a soft magnetic core allows for a smaller amount of permanent magnets. Note that the strength of the magnetic field that can be generated is not significantly different whether the core is made of soft magnetic material or permanent magnets.

[0024] Furthermore, the first magnetic pole portion of one of the pair of magnetic field generating members faces the second magnetic pole portion (corresponding to the third magnetic pole portion) of the other of the pair of magnetic field generating members, and the second magnetic pole portion of one of the pair of magnetic field generating members faces the first magnetic pole portion (corresponding to the fourth magnetic pole portion) of the other of the pair of magnetic field generating members, with the spatial gap 50 in between. This allows a magnetic field to be generated in the spatial gap 50.

[0025] In the magnetic field generator 100 of this embodiment, the dimensions of the soft magnetic cores 1-F, 2-F, 3-F, and 4-F corresponding to the magnetic pole sections in the XY plane were 50 × 70 mm (the longitudinal direction was the X direction), the longitudinal dimension (Y direction) of the yokes 11, 12, 13, 21, 22, and 23 was 180 mm, and the width (Z direction) of the air gap 50 was 24 mm. The strength of the magnetic field generated by the magnetic field generator 100 of this embodiment was calculated using an electromagnetic field analysis simulation. A neodymium sintered magnet was used as the permanent magnet material. The calculation results showed a magnetic flux density of 1.4 T at the center of the air gap 50 in the region between the magnetic pole sections. For comparison, a magnetic field generator configured with a conventional annular Halbach array was also simulated under the same conditions of the magnetic pole section dimensions and the longitudinal dimension (180 mm) of the magnetic circuit. The magnetic flux density at the center of the air gap 50 in the region between the magnetic pole sections was 1.1 T. Furthermore, the total number of permanent magnets used in the magnetic field generator 100 of this embodiment is approximately 30% less than that used in a magnetic field generator with a conventional annular Halbach array. From the above calculation results, it is clear that the magnetic field generator 100 of this embodiment can generate a stronger magnetic field using fewer permanent magnets than the conventional configuration.

[0026] The magnetic field generator 100 of this embodiment has a magnetic pole portion shape suitable for efficiently generating a high magnetic field with a limited number of permanent magnets. Referring to FIG. 3, it is effective to configure the X-axis dimension A and Z-axis dimension C of the soft magnetic cores (3-F and 4-F in FIG. 3) corresponding to each magnetic pole portion at an appropriate ratio. For a given amount of magnet used, as the ratio A / C increases, the contribution of permanent magnets 3-B and 3-C decreases, resulting in a magnetic pole portion closer to a simple magnetic pole portion consisting of only permanent magnet 3-A. Conversely, as the ratio A / C decreases, the contribution of permanent magnet 3-A decreases, resulting in a magnetic pole portion closer to a conventional annular Halbach array configuration. To maximize the benefits of the magnetic field generator 100 of this embodiment, it is desirable for the ratio A / C to be greater than or equal to 0.2 and less than or equal to 3.0.

[0027] In this embodiment, the soft magnetic core shown in FIG. 3 has a rectangular shape with sides A and C when viewed from the Y direction. However, the shape of the soft magnetic core is not limited to this. For example, the cross-sectional shape of the soft magnetic core may be a trapezoid (with the long base of the trapezoid closer to the air gap 50) on a plane perpendicular to the axis connecting the centers of the first and second magnetic pole pieces connected via a magnetic flux route. In this case, for example, in FIG. 3, permanent magnets 3-B, 3-C, 4-B, and 4-C and yokes 22 and 23 are tilted from the XY plane to match the shape of the soft magnetic core, and magnetic flux routes 25 and 26 are therefore configured on a plane tilted from the XY plane. In the case of a trapezoid, the ratio A3 / C of the height C parallel to the Z direction to the average value A3 of the long base A1 and short base A2 perpendicular to the Z direction is preferably 0.2 or more and 3.0 or less. Even with this configuration, magnetic flux is concentrated three-dimensionally in the soft magnetic core from a plurality of magnetic flux routes, and a strong magnetic field can be generated in the air gap 50, as in this embodiment.

[0028] [Second embodiment] The second embodiment proposes a magnetic refrigeration device that uses the magnetic field generating device of the first embodiment.

[0029] FIG. 5 is a perspective view showing a magnetic refrigeration device 200 according to the second embodiment. The magnetic field generator 100 has the same configuration as the first embodiment, with a pair of magnetic field generating members arranged opposite each other across a spatial gap 50. In the magnetic refrigeration device 200 according to the second embodiment, a flat-plate-shaped filled container 80 filled with a magnetic working material is placed within the spatial gap 50. The upper and lower magnetic field generating members 10 and 20 are fixed to the shaft of a rotating motor (not shown) and rotate around a rotation axis 60 by a rotation mechanism (not shown). This rotation mechanism rotates the pair of magnetic field generating members together around the rotation axis 60, which is parallel to the Z direction and passes through the midpoint of a line segment connecting the centers of the first and second magnetic poles connected via a magnetic flux route, assuming that the direction in which the pair of magnetic field generating members are aligned is the Z direction. In this way, the magnetic field generator 100 rotates in the in-plane direction of the flat-plate-shaped filled container 80. At this time, since the filling container 80 is fixed, the magnetic working material in the filling container 80 is repeatedly magnetized and demagnetized at a constant cycle in accordance with the rotational movement of the magnetic field generating device.

[0030] FIG. 6 shows a more detailed schematic diagram of the filled container 80. In this embodiment, the filled container 80 is divided into eight segments (80-1 to 80-8) that are separated from each other as individual containers. While an example divided into eight segments is described here, this is not limited to this, and the configuration may be one divided into at least four segments. The size of each segment roughly corresponds to the size of the magnetic pole part of the magnetic field generator. That is, a segment is magnetized only when the magnetic pole part comes within the segment's area, and the other segments are demagnetized. Each segment is connected to four pipes (e.g., pipes 110-A, 110-B, 110-C, and 110-D in the case of segment 80-1). The heat exchange fluid circulating through the magnetic refrigeration device 200 flows through these pipes into the filled container 80 and transports heat by exchanging heat with the magnetic working material inside. The same applies to pipes 120-A to 120-D to 180-A to 180-D of segments 80-2 to 80-8.

[0031] FIG. 7 shows a schematic diagram of the circulation path in the magnetic refrigeration apparatus of this embodiment. As described in FIG. 6, the filled container 80 is connected to the circulation system of the apparatus through the piping of each segment. For clarity, FIG. 7 only shows the paths of some of the segments 80-1 and 80-3. For segments 80-1 and 80-3, the first piping (110-A and 130-A in FIG. 6) is connected to the first high-temperature side rotary valve 81, the third piping (110-C and 130-C in FIG. 6) is connected to the second high-temperature side rotary valve 82, the fourth piping (110-D and 130-D in FIG. 6) is connected to the first low-temperature side rotary valve 83, and the second piping (110-B and 130-B in FIG. 6) is connected to the second low-temperature side rotary valve 84. The rotary valves 81, 82, 83, and 84 are movable valves that control the flow of the heat exchange fluid in conjunction with the movement of the rotation mechanism, and open and close the connected flow paths in synchronization with the rotational movement of the magnetic field generating device 100. Here, an example in which the number of movable valves is four has been described, but the number of movable valves is not limited to this. Figure 7 schematically shows how only the flow paths connected to specific segments are connected by the rotary valves. The heat exchange fluid within the device is constantly circulated by a pump 73.

[0032] FIG. 7 shows the path when segment 80-1 is magnetized. The operation of the magnetic refrigeration device 200 of this embodiment will be described using this diagram. First, when the magnetic pole of the magnetic field generator 100 is positioned at segment 80-1, segment 80-1 and segment 80-5, which are 180° apart in the plane, are magnetized. Conversely, segments 80-3 and 80-7, which are 90° apart in the plane from segment 80-1, are completely demagnetized because their magnetic poles are far apart. In segment 80-3, the magnetic working material absorbs heat due to demagnetization, causing its temperature to drop. At this time, the low-temperature side rotary valves 83 and 84 connected to segment 80-3 are open, and the heat exchange fluid circulated by pump 73 flows in the direction indicated by the white arrows in the figure and is cooled by heat exchange with the magnetic working material inside. The cooled fluid then flows through rotary valve 84 into cold head 71, lowering its temperature. The heat exchange fluid discharged from the cold head 71 enters the rotary valve 81 on the high-temperature side and flows through the piping connected to it to segment 80-1 in the direction of the black arrow in the figure. As described above, segment 80-1 is excited, so the magnetic working material inside it generates heat. The fluid flowing into segment 80-1 exchanges heat with the magnetic working material, increasing its temperature, and then flows through the piping to rotary valve 82. The heated heat exchange fluid flows to the heat exhaust heat exchanger 72, where it exchanges heat with the outside, decreasing its temperature, and circulates within the device via pump 73.

[0033] The high-temperature rotary valves 81 and 82 are also connected to the piping of the demagnetized segment 80-3, and the low-temperature rotary valves 83 and 84 are also connected to the piping of the magnetized segment 80-1, but these pipings are closed by the rotary valves so that the flow paths are not connected. This operation controls the direction of the heat exchange fluid flowing through each segment, so that the heat exchange fluid flows in only one direction within the segment depending on whether it is magnetized or demagnetized, and heat is transported to both the low-temperature and high-temperature sides.

[0034] In this way, the filling container 80, pump 73, cold head 71, exhaust heat exchanger 72, and movable valve are connected by piping to form a circulation path through which the heat exchange fluid circulates, and the cold head 71 is cooled by the magnetic field generated by the magnetic field generating device 100 and the magnetocaloric effect of the magnetic working material.

[0035] 7, the magnetic field generator 100 rotates, magnetizing the adjacent segments 80-2 and 80-6, and completely demagnetizing 80-4 and 80-8. The rotary valve opens and closes accordingly, connecting the magnetized and demagnetized segments to the flow path, and heat transfer similar to that described above occurs. The above operations are repeated as the magnetic field generator 100 rotates, thereby achieving the function of cooling the cold head 71.

[0036] In this embodiment, the magnetic working material is gadolinium (Gd), and the permanent magnet is NdFe. 14 Although we used neodymium magnets with B as the main phase and water as the heat exchange fluid, other materials may also be used. For example, other materials for the magnetic working material include La(Fe,Si), a metamagnetic material with a high magnetocaloric effect. 13 Also, Nd2Fe is applicable to permanent magnets. 14 A rare earth magnet in which neodymium (Nd) with a B-type crystal structure is substituted with an inexpensive rare earth element such as La or Ce may also be used.

[0037] [Third embodiment] The third embodiment proposes a configuration of a magnetic field generating device when the number of magnetic flux routes of the magnetic field generating member is N = 2. Since the third embodiment is a modified example of the first embodiment, the explanation will focus on the differences and omit redundant explanations.

[0038] FIG. 8 shows a perspective view of a magnetic field generator 100 according to the third embodiment. Similar to the first embodiment, the magnetic field generator 100 includes a pair of magnetic field generating members arranged facing each other vertically (in the Z-axis direction) across a spatial gap 50. The third embodiment differs from the first embodiment in that each magnetic field generating member has two magnetic flux routes. Also, unlike the first embodiment, the soft magnetic cores 5-F (hidden and not shown), 6-F (hidden and not shown), 7-F, and 8-F are triangular prisms rather than rectangular parallelepipeds. Furthermore, because there are fewer magnetic flux routes, the number of permanent magnets and yoke components is also fewer than in the first embodiment. The other basic configuration is the same as in the first embodiment, and the lower magnetic field generating member 20 will be described as follows: two soft magnetic cores 7-F and 8-F are surrounded by four permanent magnets 7-B, 7-C, 7-D, and 7-E, and 8-B, 8-C (hidden and not shown), 8-D, and 8-E, respectively, and yokes 42 and 43 made of soft magnetic material are arranged to allow magnetic flux to flow between the soft magnetic cores 7-F and 8-F. The upper magnetic field generating member 10 has a similar configuration.

[0039] The magnetic field generator 100 of the third embodiment also has four main magnetic pole sections when viewed as a magnetic circuit, similar to the first embodiment. The first magnetic pole section is composed of permanent magnets 5-B, 5-C, 5-D, and 5-E and a soft magnetic core 5-F (hidden and not shown), the second magnetic pole section is composed of permanent magnets 6-B, 6-C, 6-D, and 6-E and a soft magnetic core 6-F (hidden and not shown), the third magnetic pole section is composed of permanent magnets 7-B, 7-C, 7-D, and 7-E and a soft magnetic core 7-F, and the fourth magnetic pole section is composed of permanent magnets 8-B, 8-C (hidden and not shown), 8-D, and 8-E and a soft magnetic core 8-F. With this configuration, a magnetic field in the -Z direction is generated in the region of the spatial gap 50 sandwiched between the first magnetic pole portion and the third magnetic pole portion, and a magnetic field in the +Z direction is generated in the region of the spatial gap 50 sandwiched between the second magnetic pole portion and the fourth magnetic pole portion.

[0040] To explain the flow of magnetic flux generated in the magnetic field generator 100 of the third embodiment, FIG. 9 schematically shows the magnetization direction of the permanent magnet and the magnetic flux routes through the magnetic field generating member. The solid arrows drawn on the permanent magnets in the figure indicate the magnetization direction of the permanent magnet. In the upper magnetic field generating member 10, there are two magnetic flux routes 35 and 36 (dotted arrows) running from the second magnetic pole portion to the first magnetic pole portion. Because the soft magnetic core has a triangular shape when viewed from the Y-axis direction and the permanent magnets and yokes are arranged along its sides, the two magnetic flux routes are on different planes. Similarly, the lower magnetic field generating member 20 also has two magnetic flux routes 45 and 46 that are not on the same plane. In this embodiment, the magnetic flux routes can also be concentrated three-dimensionally in the core.

[0041] To explain the overall operation of the magnetic circuit of this embodiment, a cross-sectional view of the magnetic pole portion is shown in Figure 10A. Figure 10A is a cross-sectional view of the XZ plane taken at the center of the Y-axis thickness of the soft magnetic cores 5-F and 7-F. Note that the solid arrows drawn on the permanent magnets in the figure indicate the magnetization direction of the permanent magnets. The magnetic flux concentrated in the soft magnetic core 5-F, which constitutes the first magnetic pole portion of the upper magnetic field generating member 10, flows to the soft magnetic core 7-F, which constitutes the third magnetic pole portion of the lower magnetic field generating member 20, generating a magnetic field in the -Z direction in the spatial gap 50 between the soft magnetic cores 5-F and 7-F.

[0042] FIG. 10B shows a top view of the lower magnetic field generating member 20 as viewed from the Z direction. The solid arrows drawn on the permanent magnets in the figure indicate the magnetization direction of the permanent magnets. As described above, the magnetic flux flowing through the soft magnetic core 7-F passes through the magnetic flux routes 45 and 46 of the yokes 42 and 43 and is concentrated in the soft magnetic core 8-F constituting the fourth magnetic pole portion. Although not shown, the concentrated magnetic flux flows to the soft magnetic core 6-F of the upper magnetic field generating member 10, which is located directly above the soft magnetic core 8-F in the Z direction, generating a magnetic field in the +Z direction in the region of the air gap 50 between the soft magnetic cores 8-F and 6-F. This mechanism allows the present embodiment to generate a magnetic field in the Z direction in a specific region of the air gap 50.

[0043] In addition, permanent magnets 5-D, 5-E, 6-D, 6-E, 7-D, 7-E, 8-D, and 8-E adjacent to the soft magnetic core in the Y direction act to confine the magnetic flux that tends to spread in the ±Y-axis directions within the space gap 50, and these permanent magnets also effectively work to increase the magnetic field strength within the space gap 50.

[0044] In the magnetic field generator of this embodiment, the dimensions of the soft magnetic cores 5-F, 6-F, 7-F, and 8-F corresponding to the magnetic pole sections in the XY plane were 50 × 70 mm (the longitudinal direction was the X direction), the longitudinal dimension (Y direction) of the yokes 32, 33, 42, and 43 was 180 mm, the apex angle θ of the triangle of the soft magnetic core (FIG. 10A) was 30°, and the width (Z direction) of the air gap 50 was 24 mm. The strength of the magnetic field generated by the magnetic field generator of this embodiment was calculated using electromagnetic field analysis simulation. A neodymium sintered magnet was used as the permanent magnet material. As a result of the calculation, a magnetic flux density of 1.5 T was obtained at the center of the air gap 50 in the area between the magnetic pole sections. For comparison, a simulation was also performed on a magnetic field generator configured with a conventional annular Halbach array, assuming similar magnetic pole part dimensions and magnetic circuit longitudinal dimension (180 mm) and the same number of permanent magnets as in this embodiment. The magnetic flux density at the center of the spatial gap 50 in the area between the magnetic pole parts was 1.1 T. From the above calculation results, the magnetic field generator 100 of this embodiment can generate a stronger magnetic field using the same number of permanent magnets as the conventional configuration. Conversely, it is possible to achieve the magnetic field strength generated by the conventional configuration with a smaller number of magnets than the conventional configuration.

[0045] The magnetic field generator 100 of this embodiment has a magnetic pole part shape suitable for efficiently generating a high magnetic field with a limited number of permanent magnets. Referring to FIG. 10A, it is effective to set the apex angle θ of the isosceles triangle in the cross section of the soft magnetic core corresponding to each magnetic pole part (5-F and 7-F in FIG. 10A) to an appropriate value. As the apex angle θ increases, the magnetization direction of the permanent magnets 5-B and 5-C approaches a simple magnetic pole part that is uniformly magnetized in the -Z direction. Conversely, as the apex angle θ decreases, the magnetic pole part approaches a conventional annular Halbach array configuration. To maximize the benefits of the magnetic field generator of this embodiment, it is desirable for the apex angle θ to be 20°≦θ≦90°.

[0046] The magnetic field generating device 100 of this embodiment may be applied to the magnetic refrigeration device 200 of the second embodiment.

[0047] In addition, in the present embodiment, the case where the number of magnetic flux routes is N=2 has been described, and in the first embodiment, the case where the number of magnetic flux routes is N=3 has been described, but the present invention is not limited to these and may be such that N>3. In other words, it is sufficient that N≧2. [Explanation of symbols]

[0048] 1-A~E, 2-A~E, 3-A~E, 4-A~E, 5-B~E, 6-B~E...Permanent magnet, 1-F, 2-F, 3-F, 4-F, 5-F, 6-F, 7-F...soft magnetic core, 10...Upper magnetic field generating member, 11, 12, 13, 21, 22, 23, 32, 33, 42, 43…York, 14, 15, 16, 24, 25, 26, 35, 36, 45, 46...Flux route, 20...Lower magnetic field generating member, 50...spatial gap, 60...rotation axis, 71...Cold head, 72... Waste heat exchanger, 73...pump, 80...filled container, 81, 82, 83, 84...Rotary valves, 100...magnetic field generator, 110-A, 110-B, 110-C, 110-D...Piping, 200...Magnetic refrigeration device

Claims

1. A magnetic field generating device having a pair of magnetic field generating members arranged opposite to each other with a spatial gap therebetween, the magnetic field generating member is composed of a soft magnetic material and a permanent magnet, Each of the magnetic field generating members has a first magnetic pole portion and a second magnetic pole portion that generate a magnetic field in the spatial gap, and there are N (N≧2) magnetic flux routes along which magnetic flux flows from the second magnetic pole portion to the first magnetic pole portion through the magnetic field generating member, the N magnetic flux routes include a first magnetic flux route passing through a first yoke and a second magnetic flux route passing through a second yoke different from the first yoke and on a plane different from the first magnetic flux route, Each of the first magnetic pole portion and the second magnetic pole portion has at least N permanent magnets arranged around a core of a soft magnetic material, the permanent magnets of the first magnetic pole portion being magnetized in a direction that magnetizes the core of the soft magnetic material to a first polarity, and the permanent magnets of the second magnetic pole portion being magnetized in a direction that magnetizes the core of the soft magnetic material to a second polarity, the first magnetic pole portion of one of the pair of magnetic field generating members faces the second magnetic pole portion of the other of the pair of magnetic field generating members across the spatial gap, and the second magnetic pole portion of one of the pair of magnetic field generating members faces the first magnetic pole portion of the other of the pair of magnetic field generating members, A magnetic field generating device, characterized in that the first magnetic flux route and the second magnetic flux route enter the soft magnetic core from different faces of the soft magnetic core.

2. In claim 1, The magnetic field generating device is characterized in that the spatial gap is a spatial gap in which a flat-plate-shaped filling container filled with a magnetic working material is placed.

3. In claim 1, A magnetic field generating device characterized in that the number of magnetic flux routes in the magnetic field generating member is N=3.

4. In claim 3, A magnetic field generating device characterized in that the cross-sectional shape of the soft magnetic core is rectangular on a plane perpendicular to the axis connecting the center points of the first magnetic pole portion and the second magnetic pole portion connected via the magnetic flux route, and when the direction in which the pair of magnetic field generating members are arranged is the Z direction, the ratio A / C of the side C of the rectangle parallel to the Z direction to the side A perpendicular to the Z direction is 0.2 or more and 3.0 or less.

5. In claim 3, A magnetic field generating device characterized in that the cross-sectional shape of the soft magnetic core is trapezoidal on a plane perpendicular to the axis connecting the center points of the first magnetic pole portion and the second magnetic pole portion connected via the magnetic flux route, the long base of the trapezoid is arranged on the side closer to the spatial gap, and when the direction in which the pair of magnetic field generating members are arranged is the Z direction, the ratio A3 / C of the height C of the trapezoid parallel to the Z direction to the average value A3 of the long base A1 and short base A2 perpendicular to the Z direction is 0.2 or more and 3.0 or less.

6. In claim 1, A magnetic field generating device characterized in that the number of magnetic flux routes in the magnetic field generating member is N=2.

7. In claim 6, A magnetic field generating device characterized in that the cross-sectional shape of the soft magnetic core is approximately an isosceles triangle on a plane perpendicular to an axis connecting the center points of the first magnetic pole portion and the second magnetic pole portion connected via the magnetic flux route, and the apex angle θ of the isosceles triangle is 20°≦θ≦90°.

8. A magnetic refrigeration device using the magnetic field generating device according to any one of claims 1 to 7, a rotation mechanism that rotates the magnetic field generating device; a flat-plate-shaped filling container disposed in the spatial gap sandwiched between the pair of magnetic field generating members of the magnetic field generating device; a pump for circulating a heat exchange fluid; a cold head cooled by the heat exchange fluid; a heat rejection heat exchanger that rejects heat from the heat exchange fluid; a movable valve that controls the flow of the heat exchange fluid in conjunction with the movement of the rotating mechanism, The magnetic field generating device rotates in the in-plane direction of the flat-plate-shaped filling container, The filling container is filled with a magnetic working material, the filling vessel, the pump, the cold head, the exhaust heat exchanger, and the movable valve are connected by piping to form a circulation path through which the heat exchange fluid circulates; A magnetic refrigeration apparatus, characterized in that the cold head is cooled by the magnetic field generated by the magnetic field generator and the magnetocaloric effect of the magnetic working material.

9. In claim 8, The magnetic refrigeration device is characterized in that, when the direction in which the pair of magnetic field generating members are aligned is the Z direction, the rotation mechanism rotates the pair of magnetic field generating members together around a rotation axis that is parallel to the Z direction and passes through the midpoint of a line segment connecting the center points of the first magnetic pole portion and the second magnetic pole portion connected via the magnetic flux route.

10. In claim 8, A magnetic refrigeration apparatus characterized in that the filling container is divided into at least four segments.

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