Permanent electromagnet device

Abstract

In permanent electromagnet devices, the attraction force per unit area is improved. [Solution] The permanent electromagnet device 10 comprises a plurality of first permanent magnets 10a, a plurality of second permanent magnets 10b, a coil 10c capable of reversing the magnetization direction of the second permanent magnets 10b, and a top yoke 10t that covers the end 10p of the second permanent magnet 10b that is closer to the magnetic material W. Each of the plurality of first permanent magnets 10a is positioned between the two top yokes 10t, and one end 10s and the other end 10n of the first permanent magnet 10a are in contact with the other of the two top yokes 10t, and the total area of ​​the contact surfaces Sc with the first permanent magnets 10a is the same for all of the top yokes 10t.

Description

Technical Field

[0001] The present disclosure relates to a permanent magnet device.

Background Art

[0002] In the permanent magnetic adsorption device disclosed in Japanese Patent Application Laid-Open No. 2017-213650, a plurality of magnetic pole units are housed in a case having a rectangular shape in plan view so as to be arranged in a matrix. An alnico magnet and a rare earth magnet typified by a neodymium magnet are used for the magnetic pole unit. The alnico magnet is fixed in alignment with the central position of the plane of the magnetic pole unit. An iron core is stacked on the alnico magnet. A coil is disposed outside the alnico magnet. A rare earth magnet is disposed on the coil.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the permanent magnetic adsorption device disclosed in Japanese Patent Application Laid-Open No. 2017-213650, in order to utilize the magnetic force of the rare earth magnet disposed on the outermost side of the plurality of magnetic pole units arranged in a matrix, an outer yoke needs to be provided further outside thereof. However, since the outer yoke is provided, the area of the adsorption surface to which a magnetic body can be adsorbed increases, so that the adsorption force per unit area decreases.

[0005] The present disclosure aims to solve the above-described problems.

Means for Solving the Problems

[0006] Aspects of the present disclosure are permanent electromagnet devices comprising: a plurality of first permanent magnets; a plurality of second permanent magnets arranged in a grid; a coil wound around the outer circumference of each of the plurality of second permanent magnets, capable of reversing the magnetization direction of the second permanent magnet by the flow of an electric current; and a top yoke covering one of the two ends of the second permanent magnet that extends along the magnetization direction, the end closer to a magnetic material that can be attracted by the permanent electromagnet device, wherein each of the plurality of first permanent magnets is positioned between two adjacent top yokes, one of the two top yokes abuts against one end of the first permanent magnet where one magnetic pole is formed, and the other of the two top yokes abuts against the other end of the first permanent magnet where the other magnetic pole is formed, and the total area of ​​the contact surfaces of the top yokes with the first permanent magnets that the top yokes abut is the same for the plurality of top yokes. [Effects of the Invention]

[0007] According to this disclosure, the adsorption force per unit area of ​​the adsorption surface on which magnetic materials can be adsorbed in a permanent electromagnet device is improved. [Brief explanation of the drawing]

[0008] [Figure 1] Figures 1A and 1B illustrate the configuration of a permanent electromagnet device. [Figure 2] Figure 2 shows an example of the arrangement of the first permanent magnet and the second permanent magnet. [Figure 3] Figures 3A and 3B illustrate the contact surfaces where the top yoke contacts the first permanent magnet. [Figure 4] Figure 4 shows an example of the arrangement of the first permanent magnet and the second permanent magnet. [Figure 5] Figure 5 shows an example of the arrangement of the first permanent magnet and the second permanent magnet. [Figure 6] Figure 6 shows an example of the arrangement of the first permanent magnet and the second permanent magnet. [Figure 7] Figure 7 shows an example of the arrangement of the first permanent magnet and the second permanent magnet. [Figure 8] Figure 8 shows an example of the arrangement of the first permanent magnet and the second permanent magnet. [Figure 9] Figure 9 shows an example of the arrangement of the first permanent magnet and the second permanent magnet. [Figure 10] Figure 10 shows an example of the arrangement of the first permanent magnet and the second permanent magnet. [Figure 11] Figure 11 is a diagram illustrating the contact surface of the top yoke with the fewest contacting first permanent magnets. [Figure 12] Figures 12A, 12B, 12C, and 12D illustrate the shape of the top yoke. [Modes for carrying out the invention]

[0009] Figures 1A and 1B illustrate the configuration of the permanent electromagnet device 10. When the permanent electromagnet device 10 has an attractive force, it can attract a magnetic material W. The permanent electromagnet device 10 has a plurality of first permanent magnets 10a, a plurality of second permanent magnets 10b, a plurality of coils 10c, and a top yoke 10t.

[0010] The first permanent magnet 10a is a neodymium magnet containing, for example, neodymium in addition to iron. The first permanent magnet 10a has a rectangular prism shape with an axis in the direction of magnetization of the first permanent magnet 10a. The second permanent magnet 10b is an alnico magnet containing, for example, aluminum, nickel, and cobalt in addition to iron. The second permanent magnet 10b has a cylindrical shape with an axis in the direction of magnetization of the second permanent magnet 10b.

[0011] The top yoke 10t is made of ferromagnetic steel and allows a magnetic flux B corresponding to the magnetic force generated by the permanent electromagnet device 10 to pass through it. The top yoke 10t has a rectangular prism shape. When the second permanent magnet 10b and the top yoke 10t are viewed from the Z direction, the cross-section of the second permanent magnet 10b perpendicular to the axis of the second permanent magnet 10b is contained within the cross-section of the top yoke 10t perpendicular to the axis of the top yoke 10t.

[0012] As will be described later with reference to FIG. 2, the plurality of second permanent magnets 10b are arranged in a lattice pattern on a plane extending in the X and Y directions that intersect each other. The magnetization direction of each of the plurality of second permanent magnets 10b is along the Z direction. The Z direction intersects both the X direction and the Y direction. FIGS. 1A and 1B show the configuration of the permanent magnet device 10 as viewed from the Y direction. That is, the configuration of the permanent magnet device 10 in the X and Z directions is illustrated.

[0013] FIG. 1A shows a configuration example of the permanent magnet device 10 in a released state where the above-described attracting force of the permanent magnet device 10 is released. The magnetization directions of the second permanent magnets 10b adjacent to each other are opposite to each other.

[0014] In the example shown in FIG. 1A, four second permanent magnets 10b are arranged from left to right along the X direction. Among these four second permanent magnets 10b, the magnetization direction of the leftmost second permanent magnet 10b is the positive direction of the Z direction. The magnetization direction of the second permanent magnet 10b from the left and the third from the right is the negative direction of the Z direction. The magnetization direction of the third permanent magnet 10b from the left and the second from the right is the positive direction of the Z direction. The magnetization direction of the rightmost second permanent magnet 10b is the negative direction of the Z direction.

[0015] The coil 10c is wound around the outer periphery of each of the plurality of second permanent magnets 10b. When an electric current flows through the coil 10c, the magnetization direction of the second permanent magnet 10b can be reversed. The permanent magnet device 10 in which the magnetization directions of the four second permanent magnets 10b shown in FIG. 1A are reversed will be described later with reference to FIG. 1B.

[0016] Of the two ends of the second permanent magnet 10b that extend along the magnetization direction of the second permanent magnet 10b, the end 10p closer to the magnetic body W that can be attracted by the permanent electromagnetic device 10 when the permanent electromagnetic device 10 has an attracting force is covered by the top yoke 10t. Therefore, a plurality of top yokes 10t are arranged in a grid pattern together with a plurality of second permanent magnets 10b on a plane extending in the X and Y directions that intersect each other. Each of the plurality of first permanent magnets 10a is arranged between two top yokes 10t adjacent to each other in the X and Y directions. Only one first permanent magnet 10a is arranged between the two top yokes 10t.

[0017] The height h of the first permanent magnet 10a in the Z direction is lower than the height of the top yoke 10t in the Z direction. In the present embodiment, for all the first permanent magnets 10a, the height h of the first permanent magnet 10a is the same. In the example shown in FIG. 1A, four top yokes 10t are arranged from left to right along the X direction. Among these four top yokes 10t, a first permanent magnet 10a is arranged between the leftmost top yoke 10t and the second top yoke 10t from the left and the third top yoke 10t from the right. The magnetization direction of the first permanent magnet 10a is the positive direction of the X direction.

[0018] A first permanent magnet 10a is arranged between the second top yoke 10t from the left and the third top yoke 10t from the right and the third top yoke 10t from the left and the second top yoke 1 from the right. The magnetization direction of the first permanent magnet 10a is the negative direction of the X direction. A first permanent magnet 10a is arranged between the third top yoke 10t from the left and the second top yoke 10t from the right and the rightmost top yoke 10t. The magnetization direction of the first permanent magnet 10a is the positive direction of the X direction. <了

[0019] One of the two top yokes 10t abuts on one end 10s where the S pole, which is one of the magnetic poles of the first permanent magnet 10a arranged between the two adjacent top yokes 10t, is formed. The other of the two top yokes 10t abuts on the other end 10n where the N pole, which is the other magnetic pole of the first permanent magnet 10a arranged between the two top yokes 10t, is formed.

[0020] Figure 1A shows a first permanent magnet 10a between two top yokes 10t adjacent to each other in the X direction. The two top yokes 10t each cover the ends 10p of two adjacent second permanent magnets 10b. Of the two adjacent second permanent magnets 10b, the magnetization direction of one second permanent magnet 10ba is in the positive Z direction, and the magnetization direction of the other second permanent magnet 10bb is in the negative Z direction.

[0021] Specifically, the end 10p of the second permanent magnet 10ba, which is covered by the top yoke 10t, has a north pole, which is the magnetic pole of the second permanent magnet 10ba. The opposite end of the second permanent magnet 10ba, opposite to the end 10p, has a south pole, which is the magnetic pole of the second permanent magnet 10ba, and is covered by a bottom yoke (not shown). The bottom yoke, like the top yoke 10t, is made of a ferromagnetic material, steel, and passes through a magnetic flux B corresponding to the magnetic force generated by the permanent electromagnet device 10.

[0022] The end 10p of the second permanent magnet 10bb, which is covered by the top yoke 10t, has a south pole, which is the magnetic pole of the second permanent magnet 10bb. The opposite end of the second permanent magnet 10bb, opposite to the end 10p, has a north pole, which is the magnetic pole of the second permanent magnet 10bb, and is covered by the bottom yoke (not shown) described above.

[0023] The top yoke 10t covering the end 10p where the north pole of the second permanent magnet 10ba is formed abuts against the end 10s where the south pole of the first permanent magnet 10a is formed. The top yoke 10t covering the end 10p where the south pole of the second permanent magnet 10bb is formed abuts against the other end 10n where the north pole of the first permanent magnet 10a is formed.

[0024] The magnetic flux B corresponding to the magnetic force generated by the permanent electromagnet device 10 in the released state is directed from one end 10s where the south pole of the first permanent magnet 10a is formed, through the first permanent magnet 10a, in the positive or negative direction of the X direction, which is the magnetization direction of the first permanent magnet 10a. The magnetic flux B exits from the other end 10n where the north pole of the first permanent magnet 10a is formed, passes through the top yoke 10t which is in contact with the other end 10n, and heads toward the second permanent magnet 10bb which is covered by the top yoke 10t.

[0025] Magnetic flux B enters the second permanent magnet 10bb from the end 10p where the south pole of the second permanent magnet 10bb is formed. From the end 10p of the second permanent magnet 10bb, magnetic flux B travels through the second permanent magnet 10bb in the negative direction of the Z direction, which is the magnetization direction of the second permanent magnet 10bb. Magnetic flux B exits the end where the north pole of the second permanent magnet 10bb is formed, passes through the bottom yoke covering that end, and heads towards the second permanent magnet 10ba, which is covered by the bottom yoke.

[0026] Magnetic flux B enters the second permanent magnet 10ba from the end where the south pole of the second permanent magnet 10ba is formed. From the end where the south pole of the second permanent magnet 10ba is formed, magnetic flux B travels through the second permanent magnet 10ba in the positive direction of the Z direction, which is the magnetization direction of the second permanent magnet 10ba. Magnetic flux B exits the end 10p where the north pole of the second permanent magnet 10ba is formed, passes through the top yoke 10t covering that end 10p, and heads toward the end 10s where the south pole of the first permanent magnet 10a is formed, which the top yoke 10t abuts. Magnetic flux B enters the first permanent magnet 10a from the end 10s where the south pole of the first permanent magnet 10a is formed.

[0027] In other words, the magnetic flux B is confined within the permanent electromagnet device 10. The magnetic circuit formed by the magnetic flux B is closed and formed between two top yokes 10t adjacent to each other in the X direction, a first permanent magnet 10a between these two top yokes 10t, and two second permanent magnets 10ba and 10bb adjacent to each other in the X direction. The two adjacent second permanent magnets 10ba and 10bb are each covered by two adjacent top yokes 10t.

[0028] As will be described later with reference to Figure 2, multiple top yokes 10t and multiple second permanent magnets 10b, each with its end 10p covered by the multiple top yokes 10t, are also arranged in the Y direction. A first permanent magnet 10a is also placed between two adjacent top yokes 10t in the Y direction. Therefore, in the Y direction as in the X direction, the magnetic flux B is confined within the permanent electromagnet device 10. The magnetic circuit formed by the magnetic flux B is closed and formed between two adjacent top yokes 10t in the Y direction, the first permanent magnet 10a between those two top yokes 10t, and the two adjacent second permanent magnets 10b in the Y direction.

[0029] In that state, even if a magnetic material W is placed near the permanent electromagnet device 10, the magnetic flux B does not pass through the magnetic material W. In that case, the permanent electromagnet device 10 does not possess any attractive force. That is, the permanent electromagnet device 10 is in the released state described above. Therefore, the permanent electromagnet device 10 does not attract or hold the magnetic material W.

[0030] As described above, by flowing current through coil 10c, the magnetization direction of the second permanent magnet 10b shown in Figure 1A can be reversed. Figure 1B shows an example of the configuration of the permanent electromagnet device 10 in the adsorption state in which the permanent electromagnet device 10 has the adsorption force described above. The magnetic material W is attracted to the permanent electromagnet device 10 with the adsorption force and is shown to be adsorbed to the permanent electromagnet device 10. When the permanent electromagnet device 10 has an adsorption force, the multiple top yokes 10t form an adsorption surface As of the permanent electromagnet device 10 in which the magnetic material W can be adsorbed.

[0031] Figure 1B differs from Figure 1A in that the magnetization direction of the second permanent magnet 10b shown in Figure 1B is opposite to that of the second permanent magnet 10b shown in Figure 1A. In Figure 1B, of the two adjacent second permanent magnets 10b, the magnetization direction of one second permanent magnet 10ba is negative in the Z direction, and the magnetization direction of the other second permanent magnet 10bb is positive in the Z direction.

[0032] Specifically, the end 10p of the second permanent magnet 10ba, which is covered by the top yoke 10t, forms the south pole, which is the magnetic pole of the second permanent magnet 10ba. The opposite end of the second permanent magnet 10ba, which is the magnetic pole of the second permanent magnet 10ba, forms the north pole, which is the magnetic pole of the second permanent magnet 10ba. The end 10p of the second permanent magnet 10bb, which is covered by the top yoke 10t, forms the north pole, which is the magnetic pole of the second permanent magnet 10bb. The opposite end of the second permanent magnet 10bb, which is the magnetic pole of the second permanent magnet 10bb, forms the south pole, which is the magnetic pole of the second permanent magnet 10bb.

[0033] Two types of magnetic fluxes, Ba and Bb, are generated by the permanent electromagnet device 10 in the adsorbed state, corresponding to the magnetic force produced. Magnetic flux Ba originates from one end 10s where the south pole of the first permanent magnet 10a is formed, and travels through the first permanent magnet 10a in the positive or negative direction of the X direction, which is the magnetization direction of the first permanent magnet 10a. Magnetic flux Ba exits from the other end 10n where the north pole of the first permanent magnet 10a is formed, passes through the top yoke 10t which is in contact with the other end 10n, and enters the magnetic material W.

[0034] The magnetic flux Ba that passes through the magnetic material W passes through the top yoke 10t that is in contact with one end 10s of the first permanent magnet 10a where the south pole is formed. The magnetic flux Ba passes through the top yoke 10t and enters the first permanent magnet 10a from the one end 10s. In other words, the magnetic circuit formed by the magnetic flux Ba is formed by two top yokes 10t adjacent to each other in the X direction, the first permanent magnet 10a between the two top yokes 10t, and the magnetic material W.

[0035] The magnetic flux Bb travels from the end 10p where the south pole of the second permanent magnet 10ba is formed, through the second permanent magnet 10ba in the negative direction of the Z direction, which is the magnetization direction of the second permanent magnet 10ba. The magnetic flux Bb exits from the end where the north pole of the second permanent magnet 10ba is formed, passes through the bottom yoke covering that end, and travels towards the second permanent magnet 10bb, which is covered by the bottom yoke. The magnetic flux Bb enters the second permanent magnet 10bb from the end where the south pole of the second permanent magnet 10bb is formed, through the second permanent magnet 10bb in the positive direction of the Z direction, which is the magnetization direction of the second permanent magnet 10bb.

[0036] The magnetic flux Bb exits from the end 10p where the north pole of the second permanent magnet 10bb is formed, passes through the top yoke 10t covering the end 10p, and enters the magnetic material W. The magnetic flux Bb that has passed through the magnetic material W passes through the top yoke 10t covering the end 10p where the south pole of the second permanent magnet 10ba is formed. The magnetic flux Bb passes through the top yoke 10t and enters the second permanent magnet 10ba from the end 10p.

[0037] That is, magnetic flux Ba passes through two top yokes 10t adjacent to each other in the X direction and the first permanent magnet 10a between those two top yokes 10t. Magnetic flux Bb passes through two top yokes 10t adjacent to each other in the X direction and two second permanent magnets 10ba and 10bb adjacent to each other in the X direction. Similarly in the X direction, magnetic flux Ba passes through two top yokes 10t adjacent to each other in the Y direction and two second permanent magnets 10ba and 10bb adjacent to each other in the Y direction. Magnetic flux Bb passes through two top yokes 10t adjacent to each other in the Y direction and two second permanent magnets 10ba and 10bb adjacent to each other in the Y direction.

[0038] Since both magnetic fluxes Ba and Bb pass through the magnetic material W, the permanent electromagnet device 10 possesses an attractive force. The permanent electromagnet device 10 attracts and holds the magnetic material W to the attraction surface As by this attractive force. Unlike the conventional technology, as is clear from Figure 1B, the outermost outer yoke is not provided in the permanent electromagnet device 10 according to this embodiment. Since the magnetic fluxes Ba and Bb pass through the magnetic material W, the outer yoke is unnecessary. Therefore, the attraction surface As of the permanent electromagnet device 10 can be made smaller than in the conventional design. In other words, the attractive force per unit area of ​​the attraction surface As is improved. In addition, the permanent electromagnet device 10 can be made smaller because the outer yoke is not provided.

[0039] Figure 2 shows an example of the arrangement of the first permanent magnet 10a and the second permanent magnet 10b. Multiple second permanent magnets 10b are arranged in a grid pattern on a plane extending in the X and Y directions, which intersect with each other. The grid pattern of the second permanent magnets 10b means that multiple second permanent magnets 10b are arranged side by side in two directions that intersect with each other on the said plane. In the example shown in Figure 2, a total of 16 second permanent magnets 10b are arranged in a 4x4 grid pattern in the X and Y directions.

[0040] Figure 2 corresponds to the permanent electromagnet device 10 as viewed in the negative Z direction, as shown in Figure 1A in the released state. The adsorption surface As of the permanent electromagnet device 10 is also shown in Figure 2.

[0041] Note that in Figure 2, the second permanent magnet 10b should not be visible because it is covered by the top yoke 10t. However, for the sake of explanation, Figure 2 shows the magnetic poles formed at the end 10p of the second permanent magnet 10b when the permanent electromagnet device 10 is released. As mentioned above, the magnetization directions of adjacent second permanent magnets 10b are opposite to each other. The multiple first permanent magnets 10a and the magnetic poles formed at both ends of each first permanent magnet 10a are also shown in Figure 2.

[0042] One end 10s of the first permanent magnet 10a, on which the south pole is formed, is in contact with one of two adjacent top yokes 10t in the X or Y direction. The other end 10n of the first permanent magnet 10a, on which the north pole is formed, is in contact with the other of the two top yokes 10t. In the example shown in Figure 2, for all first permanent magnets 10a, one of two adjacent top yokes 10t is in contact with one end 10s and the other is in contact with the other end 10n.

[0043] Multiple top yokes 10t each contact the same number of first permanent magnets 10a. In the example shown in Figure 2, each of the multiple top yokes 10t contacts two first permanent magnets 10a. In this embodiment, the width w of all first permanent magnets 10a is the same. The width w of the first permanent magnet 10a corresponds to the length of the first permanent magnet 10a along the direction intersecting the magnetization direction and the Z direction.

[0044] For example, if the magnetization direction of the first permanent magnet 10a is in the X direction, the width w of the first permanent magnet 10a is the length of the first permanent magnet 10a along the Y direction. If the magnetization direction of the first permanent magnet 10a is in the Y direction, the width w of the first permanent magnet 10a is the length of the first permanent magnet 10a along the X direction. The width w of the first permanent magnet 10a is less than or equal to the width of the top yoke 10t that abuts the first permanent magnet 10a. In this embodiment, the width w of the first permanent magnet 10a is equal to the width of the top yoke 10t that abuts the first permanent magnet 10a.

[0045] Figures 3A and 3B illustrate the contact surfaces Sc on which the top yoke 10t contacts the first permanent magnet 10a. Figure 3A shows the two contact surfaces Sc on which the top yoke 10t, which covers the end 10p of the second permanent magnet 10bk in the upper right corner of the 16 second permanent magnets 10b arranged in a 4x4 grid as shown in Figure 2, contacts the two first permanent magnets 10ai and 10aj, respectively.

[0046] As described above, in this embodiment, the height h and width w of all of the multiple first permanent magnets 10a are the same. Also, as described above, the first permanent magnet 10a has a rectangular prism shape. That is, in all of the multiple first permanent magnets 10a, the contact surface Sc on which the top yoke 10t contacts the first permanent magnet 10a is a rectangle of the same shape. Therefore, the two contact surfaces Sc shown in Figure 3A are rectangles of the same shape with height h and width w, as shown in Figure 3B. In addition, the cross-section of the first permanent magnet 10a perpendicular to the magnetization direction of the first permanent magnet 10a is a rectangle with height h and width w.

[0047] Depending on the position of the second permanent magnet 10b, the positions of the two contact surfaces Sc may differ from those shown in Figure 3A, but the two contact surfaces Sc are rectangles of the same shape. That is, in all of the multiple top yokes 10t, the area of ​​the contact surface Sc that the top yoke 10t contacts with each first permanent magnet 10a is the same.

[0048] As described above, each of the multiple top yokes 10t is in contact with two first permanent magnets 10a. In all of the multiple top yokes 10t, the total area of ​​the contact surfaces Sc of the top yoke 10t with the first permanent magnets 10a is the same and twice the area of ​​each individual contact surface Sc.

[0049] When the magnetization directions of all the second permanent magnets 10b shown in Figure 2 are reversed and the permanent electromagnet device 10 acquires an attractive force, the magnetic flux Ba passing through the first permanent magnet 10a and the contact surface Sc becomes the same. The magnetic flux Ba passing through the two contact surfaces Sc, which have the same area, passes through each top yoke 10t. Therefore, the amount of magnetic flux Ba passing through each top yoke 10t is the same. Also, in the case of the multiple second permanent magnets 10b, the magnetic flux Bb passing through the second permanent magnets 10b is also the same. Therefore, the amount of magnetic flux Bb passing through each top yoke 10t is also the same.

[0050] In other words, the total amount of magnetic flux Ba and Bb entering and leaving each top yoke 10t and the magnetic material W becomes uniform. Therefore, variations in the adsorption force on the adsorption surface As of the permanent electromagnet device 10 formed by multiple top yokes 10t are suppressed.

[0051] The embodiments described above may be modified as follows. In the following modifications, explanations that overlap with those in the embodiments will be omitted. Also, in the figures used in the following modifications, components identical to those described in the embodiments will be denoted by the same reference numerals.

[0052] (Variation 1) In the embodiment described above, the first permanent magnet 10a and the second permanent magnet 10b are arranged in the arrangement pattern shown in Figure 2. However, the first permanent magnet 10a and the second permanent magnet 10b may be arranged in other arrangement patterns. Figures 4 and 5 show examples of the arrangement of the first permanent magnet 10a and the second permanent magnet 10b. In the examples shown in Figures 4 and 5, a total of 16 second permanent magnets 10b are arranged in a 4x4 grid, similar to Figure 2.

[0053] Figures 4 and 5 show the magnetic poles formed at the end 10p of the second permanent magnet 10b when the permanent electromagnet device 10 is in the released state. The arrangement pattern of the multiple second permanent magnets 10b shown in Figures 4 and 5 differs from that in Figure 2. In Figures 4 and 5, the magnetization directions of adjacent second permanent magnets 10b are opposite to each other, as in Figure 2.

[0054] Each of the multiple first permanent magnets 10a is positioned between two top yokes 10t adjacent to each other in the X and Y directions. Only one first permanent magnet 10a is positioned between the two top yokes 10t. The multiple first permanent magnets 10a and the magnetic poles formed at both ends of each first permanent magnet 10a are also shown in Figures 4 and 5. In Figures 4 and 5, if the magnetization directions of second permanent magnets 10b positioned in the same location are opposite, then the magnetization directions of the first permanent magnets 10a positioned between the second permanent magnets 10b and the two top yokes 10t covering adjacent second permanent magnets 10b are also opposite. The arrangement pattern of the multiple first permanent magnets 10a shown in Figures 4 and 5 differs from that in Figure 2.

[0055] However, in the examples shown in Figures 4 and 5, as in Figure 2, in all first permanent magnets 10a, one and the other of adjacent top yokes 10t are in contact with one end 10s and the other end 10n of the first permanent magnet 10a, respectively.

[0056] In this modified example 1, the width w of all first permanent magnets 10a is the same. Also, although not shown in the illustration, the height h of all first permanent magnets 10a is the same, similar to the example shown in Figure 1. That is, for all of the multiple first permanent magnets 10a, the contact surface Sc on which the top yoke 10t contacts the first permanent magnet 10a is a rectangle of the same shape consisting of height h and width w. Therefore, for all of the multiple top yokes 10t, the area of ​​the contact surface Sc on which the top yoke 10t contacts each first permanent magnet 10a is the same.

[0057] Multiple top yokes 10t each abut an equal number of first permanent magnets 10a. In this modified example 1, each of the multiple top yokes 10t abuts two first permanent magnets 10a. In all of the multiple top yokes 10t, the total area of ​​the contact surfaces Sc of the top yokes 10t with the first permanent magnets 10a that the top yokes 10t abut is the same, and is twice the area of ​​each individual contact surface Sc.

[0058] Therefore, when the permanent electromagnet device 10 has an attractive force and attracts the magnetic material W to the attraction surface As, the total amount of magnetic flux Ba and Bb entering and leaving each top yoke 10t and the magnetic material W becomes uniform. As a result, variations in the attractive force on the attraction surface As of the permanent electromagnet device 10 formed by multiple top yokes 10t are suppressed.

[0059] (Modification 2) The first permanent magnet 10a and the second permanent magnet 10b may be arranged in a different arrangement pattern than that of the above-described embodiment and modified example 1. Figures 6 and 7 show examples of arrangements of the first permanent magnet 10a and the second permanent magnet 10b. In the examples shown in Figures 6 and 7, a total of 16 second permanent magnets 10b are arranged in a 4x4 grid, similar to Figure 2.

[0060] Figures 6 and 7 show the magnetic poles formed at the end 10p of the second permanent magnet 10b when the permanent electromagnet device 10 is in the released state. The arrangement pattern of the multiple second permanent magnets 10b shown in Figures 6 and 7 differs from that in Figure 2. In Figure 6, the magnetization directions of adjacent second permanent magnets 10b are opposite to each other, as in Figure 2.

[0061] In Figure 7, of the four second permanent magnets 10b arranged from left to right in the X direction, the magnetization direction of the leftmost second permanent magnet 10b and the magnetization direction of the second second permanent magnet 10b from the left are opposite to each other. The leftmost second permanent magnet 10b and the second second permanent magnet 10b from the left are adjacent to each other. The magnetization direction of the rightmost second permanent magnet 10b and the magnetization direction of the second second permanent magnet 10b from the right, which is adjacent to the rightmost second permanent magnet 10b, are opposite to each other. The rightmost second permanent magnet 10b and the second second permanent magnet 10b from the right are adjacent to each other. The same applies to the four second permanent magnets 10b arranged from top to bottom in the Y direction.

[0062] Each of the multiple first permanent magnets 10a is positioned between two top yokes 10t adjacent to each other in the Y direction. Only one first permanent magnet 10a is positioned between the two top yokes 10t. The multiple first permanent magnets 10a and the magnetic poles formed at both ends of each first permanent magnet 10a are also shown in Figures 6 and 7. In Figures 6 and 7, if the magnetization directions of the second permanent magnets 10b positioned in the same location are opposite, then the magnetization directions of the first permanent magnets 10a positioned between the second permanent magnets 10b and the two top yokes 10t covering the adjacent second permanent magnets 10b are also opposite.

[0063] In the examples shown in Figures 6 and 7, as in Figure 2, in all first permanent magnets 10a, one and the other of adjacent top yokes 10t are in contact with one end 10s and the other end 10n of the first permanent magnet 10a, respectively.

[0064] In this modified example 2, the width w of all first permanent magnets 10a is the same. Also, although not shown in the illustration, the height h of all first permanent magnets 10a is the same, similar to the example shown in Figure 1. That is, for all of the multiple first permanent magnets 10a, the contact surface Sc on which the top yoke 10t contacts the first permanent magnet 10a is a rectangle of the same shape consisting of height h and width w. Therefore, for all of the multiple top yokes 10t, the area of ​​the contact surface Sc on which the top yoke 10t contacts each first permanent magnet 10a is the same.

[0065] Multiple top yokes 10t each contact the same number of first permanent magnets 10a. In this modified example 2, each of the multiple top yokes 10t contacts one first permanent magnet 10a. In all of the multiple top yokes 10t, the total area of ​​the contact surfaces Sc of the top yokes 10t with the first permanent magnets 10a that the top yokes 10t contact is the same and equal to the area of ​​each individual contact surface Sc.

[0066] Therefore, when the permanent electromagnet device 10 has an attractive force and attracts the magnetic material W to the attraction surface As, the total amount of magnetic flux Ba and Bb entering and leaving each top yoke 10t and the magnetic material W becomes uniform. As a result, variations in the attractive force on the attraction surface As of the permanent electromagnet device 10 formed by multiple top yokes 10t are suppressed.

[0067] (Variation 3) The first permanent magnet 10a and the second permanent magnet 10b may be arranged in a different arrangement pattern than that of the above-described embodiment and modified example 1. Figures 8, 9, and 10 show examples of arrangements of the first permanent magnet 10a and the second permanent magnet 10b. In the example shown in Figure 8, a total of 16 second permanent magnets 10b are arranged in a 4x4 grid, similar to Figure 2. In the example shown in Figure 9, a total of 24 second permanent magnets 10b are arranged in a 5x5 grid. Note that no second permanent magnets 10b are placed in the center of the grid. In the example shown in Figure 10, a total of 36 second permanent magnets 10b are arranged in a 6x6 grid.

[0068] Figures 8, 9, and 10 show the magnetic poles formed at the end 10p of the second permanent magnet 10b when the permanent electromagnet device 10 is in the disengaged state. Note that in Figures 8, 9, and 10, the magnetization directions of adjacent second permanent magnets 10b are opposite to each other, as in Figure 2.

[0069] Each of the multiple first permanent magnets 10a is positioned between two top yokes 10t adjacent to each other in the X and Y directions. Only one first permanent magnet 10a is positioned between the two top yokes 10t. The multiple first permanent magnets 10a and the magnetic poles formed at both ends of each first permanent magnet 10a are also shown in Figures 8, 9, and 10.

[0070] In the examples shown in Figures 8, 9, and 10, similar to Figure 2, in all first permanent magnets 10a, one and the other of adjacent top yokes 10t are in contact with one end 10s and the other end 10n of the first permanent magnet 10a, respectively.

[0071] In this modified example 3, each of the multiple top yokes 10t is in contact with two, three, or four first permanent magnets 10a. That is, the minimum number of first permanent magnets 10a that the top yoke 10t is in contact with is two, and the maximum number of first permanent magnets 10a that the top yoke 10t is in contact with is four. The contact surface Sc is changed so that the total area of ​​the contact surface Sc of the top yoke 10t with respect to the first permanent magnets 10a that the top yoke 10t is in contact with is the same for all of the multiple top yokes 10t.

[0072] In this modified example 3, the width w of all first permanent magnets 10a is the same. When the top yoke 10t is in contact with the fewest first permanent magnets 10a, which is 2, the height he of the contact surface Sce of the top yoke 10t is greater than the height h of the contact surface Sc of the top yoke 10t when the top yoke 10t is in contact with the most first permanent magnets 10a, which is 4. In this modified example 3, when the top yoke 10t is in contact with the fewest first permanent magnets 10a, which is 2, these two first permanent magnets 10a can also be represented as first permanent magnets 10ae.

[0073] When there are three first permanent magnets 10a that the top yoke 10t is in contact with, one of the three first permanent magnets 10a is the first permanent magnet 10ae described above. The height he of the contact surface Sce of the top yoke 10t that contacts the first permanent magnet 10ae is greater than the height h of the contact surfaces Sc of the top yoke 10t that contact each of the remaining two first permanent magnets 10a that the top yoke 10t is in contact with. In Figures 8, 9, and 10 described above, the first permanent magnet 10ae is hatched for easy identification.

[0074] That is, the cross-section of the first permanent magnet 10ae perpendicular to the magnetization direction of the first permanent magnet 10ae is a rectangle with height he and width w. Figure 11 is a diagram illustrating the contact surface Sce of the top yoke 10t with the fewest contacting first permanent magnets 10ae. The contact surface Sce of the top yoke 10t that contacts the first permanent magnets 10ae with height he and width w is a rectangle with height he and width w.

[0075] The cross-sections of the first permanent magnets 10a, other than the first permanent magnet 10ae, have a rectangular shape with height h and width w. The top yoke 10t, which has the most contact with the first permanent magnets 10a, contacts the first permanent magnets 10a with height h and width w. The contact surface Sc of the top yoke 10t that contacts the first permanent magnets 10a with height h and width w is a rectangle with height h and width w as shown in Figure 3B.

[0076] In the examples shown in Figures 8, 9, and 10, the height he of the first permanent magnet 10ae is twice the height h of the first permanent magnet 10a. In this case, the area of ​​the contact surface Sce is twice that of the contact surface Sc. The top yoke 10t with the fewest contacting first permanent magnets 10ae has two contact surfaces Sce. Therefore, the total area of ​​the contact surfaces Sce of the top yoke 10t is equal to four times the area of ​​the contact surface Sc.

[0077] The top yoke 10t with the most contacting first permanent magnets 10a has four contact surfaces Sc. Therefore, the total area of ​​the contact surfaces Sc of the top yoke 10t is equal to four times the area of ​​the contact surfaces Sc. The top yoke 10t with three contacting first permanent magnets 10a has one contact surface Sce and two contact surfaces Sc, as it contacts one first permanent magnet 10ae and the other two first permanent magnets 10a. Therefore, the total area of ​​the contact surfaces Sc of the top yoke 10t is equal to four times the area of ​​the contact surfaces Sc.

[0078] In other words, in the examples shown in Figures 8, 9, and 10, the total area of ​​the contact surfaces Sc of the top yoke 10t with the first permanent magnet 10a that the top yoke 10t is in contact with is the same for all of the multiple top yokes 10t, and is four times the area of ​​each individual contact surface Sc.

[0079] Therefore, when the permanent electromagnet device 10 has an attractive force and attracts the magnetic material W to the attraction surface As, the total amount of magnetic flux Ba and Bb entering and leaving each top yoke 10t and the magnetic material W becomes uniform. As a result, variations in the attractive force on the attraction surface As of the permanent electromagnet device 10 formed by multiple top yokes 10t are suppressed.

[0080] (Modification 4) The top yoke 10t has a three-dimensional shape that contacts the end portion 10p of the second permanent magnet 10b that the top yoke 10t covers. In the embodiment described above, the top yoke 10t has a rectangular prism shape. However, the top yoke 10t may have other three-dimensional shapes.

[0081] The three-dimensional shape of the top yoke 10t may include a polygonal prism, a cylinder, or a frustocone. Such a top yoke 10t is easy to manufacture regardless of its three-dimensional shape. The axis of the three-dimensional shape perpendicular to its base is parallel to the Z direction, which is the magnetization direction of the second permanent magnet 10b. When the cylindrical second permanent magnet 10b and the top yoke 10t are viewed from the Z direction, the cross-section of the second permanent magnet 10b perpendicular to its axis is contained within the cross-section of the top yoke 10t perpendicular to its axis.

[0082] Figures 12A, 12B, 12C, and 12D illustrate the shape of the top yoke 10t. Figure 12A shows the shape of the top yoke 10t used in the embodiment described above. The top yoke 10t shown in Figure 12A includes a rectangular prism, which is a type of polygonal prism. The rectangular prism that constitutes the shape of the top yoke 10t has two flat bottom surfaces Sa and Sb perpendicular to the axis Ca of the rectangular prism. Bottom surface Sa forms part of the adsorption surface As of the permanent electromagnet device 10. Bottom surface Sb covers the end 10p of the second permanent magnet 10b. The axis Ca perpendicular to the bottom surfaces Sa and Sb is parallel to the Z direction, which is the magnetization direction of the second permanent magnet 10b.

[0083] Since the top yoke 10t has a rectangular prism shape, all of the sides of the rectangular prism parallel to the axis Ca are flat. The top yoke 10t contacts the first permanent magnet 10a, which has a rectangular prism shape, with its flat sides. That is, the two contact surfaces Sc are formed on the flat sides of the top yoke 10t.

[0084] Figures 12B, 12C, and 12D show other shapes of the top yoke 10t, respectively. The top yoke 10t shown in Figure 12B includes an octagonal prism, which is a type of polygonal prism. The octagonal prism that makes up the shape of the top yoke 10t has two flat base surfaces Sa and Sb perpendicular to the axis Ca of the octagonal prism. Base surface Sa forms part of the adsorption surface As of the permanent electromagnet device 10. Base surface Sb covers the end 10p of the second permanent magnet 10b. The axis Ca perpendicular to the base surfaces Sa and Sb is parallel to the Z direction, which is the magnetization direction of the second permanent magnet 10b.

[0085] Since the top yoke 10t has an octagonal prism shape, all of the sides of the octagonal prism parallel to the axis Ca are flat. The top yoke 10t contacts the first permanent magnet 10a, which has a rectangular prism shape, with its flat sides. That is, the two contact surfaces Sc are formed on the flat sides of the top yoke 10t.

[0086] The top yoke 10t shown in Figure 12C includes a cylinder 10tc and an octagonal prism 10tp, which is a type of polygonal prism. The cylinder 10tc has two flat base surfaces Sa and Sb perpendicular to the axis Ca of the cylinder 10tc. Base surface Sa forms part of the adsorption surface As of the permanent electromagnet device 10. Base surface Sb covers the end 10p of the second permanent magnet 10b. The axis Ca perpendicular to the base surfaces Sa and Sb is parallel to the Z direction, which is the magnetization direction of the second permanent magnet 10b. The octagonal prism 10tp, which shares an axis Ca with the cylinder 10tc, is sandwiched between the two separated cylinders 10tc in the direction of axis Ca.

[0087] Therefore, a portion of the top yoke 10t has an octagonal prism shape. The sides of the octagonal prism 10tp parallel to the axis Ca are all flat. The top yoke 10t contacts the first permanent magnet 10a, which has a rectangular prism shape, with its flat sides. That is, the two contact surfaces Sc are formed on the flat sides of the octagonal prism 10tp that is included in the portion of the top yoke 10t.

[0088] The top yoke 10t shown in Figure 12D includes a cylinder 10tc, an octagonal prism 10tp which is a type of polygonal prism, and a frustum of a cone 10td. The base Sb of the cylinder 10tc is flat and covers the end 10p of the second permanent magnet 10b. The axis Ca of the cylinder 10tc, perpendicular to the base Sb, is parallel to the Z direction, which is the magnetization direction of the second permanent magnet 10b.

[0089] The frustum of the cone 10td shares a common axis Ca with the cylinder 10tc. The frustum of the cone 10td has two flat bases Sa and Sab perpendicular to the axis Ca. The frustum of the cone 10td has a taper in the positive direction of the Z-axis. Therefore, one base Sa of the frustum of the cone 10td is smaller than the other base Sab. Base Sa forms part of the adsorption surface As of the permanent electromagnet device 10. Base Sab is in contact with the end face of the octagonal prism 10tp. The octagonal prism 10tp, which shares a common axis Ca with the cylinder 10tc and the frustum of the cone 10td, is sandwiched between the cylinder 10tc and the frustum of the cone 10td, which are positioned in the direction of the axis Ca.

[0090] Therefore, a portion of the top yoke 10t has an octagonal prism shape. The sides of the octagonal prism 10tp parallel to the axis Ca are all flat. The top yoke 10t contacts the first permanent magnet 10a, which has a rectangular prism shape, with its flat sides. That is, the two contact surfaces Sc are formed on the flat sides of the octagonal prism 10tp that is included in the portion of the top yoke 10t.

[0091] The bottom surface Sa of the top yoke 10t, which forms part of the adsorption surface As of the permanent electromagnet device 10, is polygonal in Figures 12A and 12B, and circular in Figures 12C and 12D. A circular bottom surface Sa reduces leakage flux that passes between adjacent top yokes 10t without passing through the magnetic material W, compared to a polygonal bottom surface Sa. This is because a circular bottom surface Sa allows for a relatively larger distance between the top yokes 10t compared to a polygonal bottom surface Sa.

[0092] Furthermore, when the permanent electromagnet device 10 is installed, the magnetic fluxes Ba and Bb (see Figure 1B) pass through the bottom surface Sa of the top yoke 10t, which forms part of the adsorption surface As of the permanent electromagnet device 10. The smaller the bottom surface Sa, the greater the magnetic flux density. Since the bottom surface Sa is smaller when it is circular compared to when it is polygonal, the magnetic fluxes Ba and Bb can be concentrated. Thus, when the bottom surface Sa is circular rather than polygonal, leakage flux is reduced and magnetic flux is concentrated, thus strengthening the adsorption force of the permanent electromagnet device 10. In other words, the bottom surface Sa is preferable to the polygonal shape shown in Figures 12A and 12B, as shown in Figures 12C and 12D.

[0093] Furthermore, a cover may be attached to the permanent electromagnet device 10 to prevent each of the multiple top yokes 10t from detaching from the permanent electromagnet device 10 due to being pulled by the magnetic material W. In this case, the cover is provided with through holes equal to the number of top yokes 10t, for passing through the ends of each top yoke 10t, including the bottom surface Sa of each top yoke 10t. As shown in Figure 12D, if a taper is provided at the tip of each top yoke 10t in the positive direction of the Z direction, it becomes easier to attach such a cover to the permanent electromagnet device 10.

[0094] With regard to the embodiments described above, the following additional information is disclosed.

[0095] (Note 1) The permanent electromagnet device (10) of this disclosure comprises a plurality of first permanent magnets (10a), a plurality of second permanent magnets (10b) arranged in a grid, a coil (10c) wound around the outer circumference of each of the plurality of second permanent magnets and capable of reversing the magnetization direction of the second permanent magnet by the flow of an electric current, and a top yoke (10t) covering one of the two ends of the second permanent magnet that extends along the magnetization direction, the end (10p) that is closer to the magnetic material (W) that can be attracted by the permanent electromagnet device. Each of the plurality of first permanent magnets is positioned between two adjacent top yokes, with one end (10s) of the first permanent magnet having one magnetic pole in contact with one of the two top yokes, and the other end (10n) of the first permanent magnet having the other magnetic pole in contact with the other of the two top yokes, and in all of the plurality of top yokes, the total area of ​​the contact surfaces (Sc, Sce) of the top yokes with the first permanent magnets that the top yokes contact is the same. With this configuration, the attractive force per unit area of ​​the attractive surface on which magnetic materials can be attracted in the permanent electromagnet device is improved. As a result, the permanent electromagnet device can be miniaturized. In addition, variations in the attractive force on the attractive surface are suppressed.

[0096] (Note 2) In the permanent electromagnet device described in Appendix 1, each of the multiple top yokes may be in contact with the same number of the first permanent magnets. With this configuration, variations in the attraction force on the attraction surface can be suppressed.

[0097] (Note 3) In the permanent electromagnet device described in Appendix 1, the area of ​​the contact surface in which the top yoke contacts the first permanent magnet may be the same in multiple top yokes. With such a configuration, variations in the adsorption force on the adsorption surface can be suppressed.

[0098] (Note 4) In the permanent electromagnet device described in Appendix 1, the contact surfaces of the top yokes that contact the first permanent magnet may be rectangular in shape. With such a configuration, variations in the attraction force on the attraction surface can be suppressed.

[0099] (Note 5) In the permanent electromagnet device described in Appendix 2, each of the multiple top yokes may be in contact with the two first permanent magnets. With this configuration, variations in the attraction force on the attraction surface can be suppressed.

[0100] (Note 6) The permanent electromagnet device described in Appendix 1, wherein the top yoke has a three-dimensional shape that contacts the end of the second permanent magnet covered by the top yoke, and the three-dimensional shape includes a polygonal prism, a cylinder (10tc), or a frustocone (10td), and the axis (Ca) of the three-dimensional shape perpendicular to the base surface (Sb) of the three-dimensional shape is parallel to the magnetization direction of the second permanent magnet. With such a configuration, the top yoke is easy to manufacture regardless of the three-dimensional shape.

[0101] While this disclosure has been described in detail, it is not limited to the individual embodiments described above. These embodiments can be added, replaced, modified, partially deleted, etc., in any way that does not depart from the gist of this disclosure or from the spirit of this disclosure derived from the claims and their equivalents. These embodiments can also be implemented in combination. For example, the order of operations and processes in the embodiments described above are given as examples only and are not limited thereto. The same applies when numerical values ​​or mathematical formulas are used in the description of the embodiments described above. [Explanation of Symbols]

[0102] 10…Permanent electromagnet device

Claims

1. It is a permanent electromagnet device, Multiple first permanent magnets, Multiple second permanent magnets arranged in a grid, A coil is wound around the outer circumference of each of the multiple second permanent magnets, and can reverse the magnetization direction of the second permanent magnet when an electric current flows through it. A top yoke covers one of the two ends of the second permanent magnet that extends along the magnetization direction, the end that is closer to the magnetic material that can be attracted by the permanent electromagnet device, Equipped with, Each of the plurality of first permanent magnets is positioned between two adjacent top yokes, One of the two top yokes abuts against one end of the first permanent magnet where one magnetic pole is formed, and the other of the two top yokes abuts against the other end of the first permanent magnet where the other magnetic pole is formed. A permanent electromagnet device in which, in multiple top yokes, the total area of ​​the contact surfaces of the top yokes with the first permanent magnet that the top yokes abut is the same.

2. A permanent electromagnet device according to claim 1, A permanent electromagnet device in which multiple top yokes each contact an equal number of the first permanent magnets.

3. A permanent electromagnet device according to claim 1, A permanent electromagnet device in which, in a plurality of the top yokes, the area of ​​the contact surface in which the top yokes contact the first permanent magnet is the same.

4. A permanent electromagnet device according to claim 1, A permanent electromagnet device in which, in a plurality of the top yokes, the contact surfaces of the top yokes that contact the first permanent magnet are all rectangular in shape.

5. A permanent electromagnet device according to claim 2, A permanent electromagnet device in which each of the multiple top yokes is in contact with two of the first permanent magnets.

6. A permanent electromagnet device according to claim 1, The top yoke has a three-dimensional shape that contacts the end of the second permanent magnet covered by the top yoke, The aforementioned three-dimensional shape includes a polygonal prism, a cylinder, or a truncated cone. A permanent electromagnet device in which the axis of the three-dimensional shape perpendicular to the bottom surface of the three-dimensional shape is parallel to the magnetization direction of the second permanent magnet.

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