Permanent electromagnet device

Abstract

A 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 a magnetization direction of the second permanent magnets (10b); and a top yoke (10t) that covers, from among two end portions of the second permanent magnet, an end portion (10p) closer to a magnetic body (W). Each of the plurality of first permanent magnets is disposed between two of the top yokes, one and the other of the two top yokes is in contact with one end (10s) and the other end (10n) of the first permanent magnet, and total areas of contact surfaces (Sc, Sce) with the first permanent magnet are the same for the plurality of top yokes.

Description

Permanent Magnet Device

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

[0002] In the permanent magnetic adsorption device disclosed in Japanese Patent Application Laid-Open No. 2017-213650, a plurality of magnetic pole units are accommodated 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 in 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.

[0003] 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. However, since the area of the adsorption surface to which a magnetic material can be adsorbed increases due to the provision of the outer yoke, the adsorption force per unit area decreases.

[0004] An object of the present disclosure is to solve the above-described problems.

[0005] An aspect of the present disclosure is a permanent magnet device including: a plurality of first permanent magnets; a plurality of second permanent magnets arranged in a lattice; a coil wound around each outer periphery of the plurality of second permanent magnets, the magnetization direction of the second permanent magnet being able to be reversed by flowing a current; and a top yoke covering an end of the two ends of the second permanent magnet extending along the magnetization direction, the end being closer to a magnetic material that can be attracted by the permanent magnet device. Each of the plurality of first permanent magnets is disposed between two adjacent top yokes. One of the two top yokes abuts on one end where one magnetic pole of the first permanent magnet is formed, and the other of the two top yokes abuts on the other end where the other magnetic pole of the first permanent magnet is formed. In the plurality of top yokes, the total area of the contact surfaces of the top yokes with the first permanent magnets with which the top yokes abut is the same.

[0006] 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.

[0007] The above-mentioned objectives, features, and advantages will be readily apparent from the following description of the embodiments, which will be illustrated with reference to the attached drawings.

[0008] Figures 1A and 1B illustrate the configuration of a permanent magnet device. Figure 2 shows an example of the arrangement of the first permanent magnet and the second permanent magnet. Figures 3A and 3B illustrate the contact surface of the top yoke that contacts the first permanent magnet. Figure 4 shows an example of the arrangement of the first permanent magnet and the second permanent magnet. Figure 5 shows an example of the arrangement of the first permanent magnet and the second permanent magnet. Figure 6 shows an example of the arrangement of the first permanent magnet and the second permanent magnet. Figure 7 shows an example of the arrangement of the first permanent magnet and the second permanent magnet. Figure 8 shows an example of the arrangement of the first permanent magnet and the second permanent magnet. Figure 9 shows an example of the arrangement of the first permanent magnet and the second permanent magnet. Figure 10 shows an example of the arrangement of the first permanent magnet and the second permanent magnet. Figure 11 illustrates the contact surface of the top yoke with the fewest contacting first permanent magnets. Figures 12A, 12B, 12C, and 12D illustrate the shape of the top yoke.

[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 magnetization direction 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 magnetization direction 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 using Figure 2, the multiple second permanent magnets 10b are arranged in a grid pattern on a plane extending in the X and Y directions, which intersect each other. The magnetization direction of each of the multiple second permanent magnets 10b is along the Z direction. The Z direction intersects both the X and Y directions. Figures 1A and 1B show the configuration of the permanent electromagnet device 10 as seen from the Y direction. That is, the configuration of the permanent electromagnet device 10 in the X and Z directions is illustrated.

[0013] Figure 1A shows an example of the configuration of the permanent electromagnet device 10 in the released state, where the attractive force of the permanent electromagnet device 10 described above has been released. The magnetization directions of the adjacent second permanent magnets 10b are opposite to each other.

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

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

[0016] The top yoke 10t covers the end 10p of the second permanent magnet 10b, which extends along the magnetization direction of the second permanent magnet 10b and is closer to the magnetic material W that can be attracted by the permanent electromagnet device 10 when the permanent electromagnet device 10 has an attractive force. Therefore, multiple top yokes 10t are arranged in a grid pattern together with multiple second permanent magnets 10b on a plane extending in the X and Y directions that intersect each other. Each of the multiple first permanent magnets 10a is positioned between two top yokes 10t that are adjacent to each other in the X and Y directions. There is only one first permanent magnet 10a positioned 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 this embodiment, the height h of the first permanent magnet 10a is the same for all of the first permanent magnets 10a. In the example shown in Figure 1A, four top yokes 10t are arranged from left to right along the X direction. The first permanent magnet 10a is positioned between the leftmost top yoke 10t and the second from the left and third from the right of these four top yokes 10t. The magnetization direction of the first permanent magnet 10a is the positive direction in the X direction.

[0018] A first permanent magnet 10a is positioned 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 10t from the right. The magnetization direction of the first permanent magnet 10a is negative in the X direction. A first permanent magnet 10a is positioned between the third top yoke 10t from the left and the second top yoke 10t from the rightmost position, and the rightmost top yoke 10t. The magnetization direction of the first permanent magnet 10a is positive in the X direction.

[0019] One of the two top yokes 10t abuts against one end 10s of the first permanent magnet 10a, which is positioned between two adjacent top yokes 10t, and which has a south pole (S pole) formed thereon. The other end of the two top yokes 10t abuts against the other end 10n of the first permanent magnet 10a, which is positioned between the two top yokes 10t, and which has a north pole (N pole) formed thereon.

[0020] Figure 1A shows a first permanent magnet 10a between two adjacent top yokes 10t 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, which is the south pole, 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, which is 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 deactivated 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 adjacent top yokes 10t in the X direction, a first permanent magnet 10a between the two top yokes 10t, and two adjacent second permanent magnets 10ba and 10bb in the X direction. The two adjacent second permanent magnets 10ba and 10bb are each covered by the 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 arranged 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 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 the 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 to 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 in the negative Z direction, and the magnetization direction of the other second permanent magnet 10bb is in the positive 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 end opposite to the end 10p 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 end opposite to the end 10p 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 depending on the magnetic force produced by the permanent electromagnet device 10 in the adsorption state. 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 abuts against 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. The magnetic flux Bb travels 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 the 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 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 Y direction and the 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. That is, 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 seen in the released state shown in Figure 1A. 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 abut an equal number of first permanent magnets 10a. In the example shown in Figure 2, each of the multiple top yokes 10t abuts 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, when 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. When 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 not more than the width of the top yoke 10t that abuts on the first permanent magnet 10a. In the present embodiment, the width w of the first permanent magnet 10a is equal to the width of the top yoke 10t that abuts on the first permanent magnet 10a.

[0045] FIGS. 3A and 3B are diagrams for explaining the contact surface Sc where the top yoke 10t abuts on the first permanent magnet 10a. FIG. 3A shows two contact surfaces Sc where the top yoke 10t covering the end 10p of the right upper corner most second permanent magnet 10bk among the 16 second permanent magnets 10b arranged in a 4-row × 4-column grid shown in FIG. 2 abuts on two first permanent magnets 10ai and 10aj, respectively.

[0046] As described above, in the present embodiment, in all of the plurality of first permanent magnets 10a, the height h and the width w of the first permanent magnet 10a are the same. Also, as described above, the first permanent magnet 10a has a quadrangular prism shape. That is, in all of the plurality of first permanent magnets 10a, the contact surface Sc where the top yoke 10t abuts on the first permanent magnet 10a is a rectangle of the same shape. Therefore, the two contact surfaces Sc shown in FIG. 3A are rectangles of the same shape composed of the height h and the width w as shown in FIG. 3B. Also, the cross section of the first permanent magnet 10a perpendicular to the magnetization direction of the first permanent magnet 10a is a rectangle of the height h and the width w.

[0047] Depending on the position of the second permanent magnet 10b, the positions of the two contact surfaces Sc may be different from those in FIG. 3A, but the two contact surfaces Sc are rectangles of the same shape. That is, in all of the plurality of top yokes 10t, the area of the contact surface Sc where the top yoke 10t abuts on each first permanent magnet 10a is the same.

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

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

[0050] That is, the total amount of the magnetic fluxes Ba and Bb entering and leaving each top yoke 10t and the magnetic body W becomes uniform. Therefore, the variation in the attractive force on the adsorption surface As of the permanent magnet device 10 formed by the plurality of top yokes 10t is suppressed.

[0051] The above-described embodiment may be modified as follows. In the following modification examples, descriptions overlapping with the embodiment are omitted. Also, the figures used in the following modification examples are given the same reference numerals for the same configurations as those described in the embodiment.

[0052] (Modification Example 1) In the above-described embodiment, the first permanent magnet 10a and the second permanent magnet 10b are arranged in the arrangement pattern shown in FIG. 2. However, the first permanent magnet 10a and the second permanent magnet 10b may be arranged in other arrangement patterns. FIGS. 4 and 5 are diagrams showing arrangement examples of the first permanent magnet 10a and the second permanent magnet 10b. In the examples shown in FIGS. 4 and 5, as in FIG. 2, a total of 16 second permanent magnets 10b are arranged in a 4-row × 4-column grid pattern.

[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 is different 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 1A. 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 surface Sc of the top yoke 10t with respect to the first permanent magnets 10a 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 the 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 Modification 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 in the X direction from left to right, 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 in the Y direction from top to bottom.

[0062] Each of the multiple first permanent magnets 10a is positioned between two adjacent top yokes 10t 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 adjacent second permanent magnets 10b are also opposite.

[0063] In the examples shown in Figures 6 and 7, 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.

[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 1A. 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 abut an equal number of first permanent magnets 10a. In this modified example 2, each of the multiple top yokes 10t abuts one first permanent magnet 10a. In all of the multiple top yokes 10t, the total area of ​​the contact surface Sc of the top yoke 10t with the first permanent magnets 10a that the top yoke 10t abuts 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 the multiple top yokes 10t are suppressed.

[0067] (Modification 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 Modification 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 released 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 contacts, 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 respective contact surfaces Sc of the top yoke 10t that contact each of the remaining two first permanent magnets 10a. 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 that has the fewest contacting first permanent magnets 10ae. The contact surface Sce of the top yoke 10t that contacts the first permanent magnets 10ae of 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 the area 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 surface 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 the 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 covered by the top yoke 10t. In the above embodiment, 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 the base surface of the three-dimensional shape 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 the axis of the second permanent magnet 10b is contained inside the cross-section of the top yoke 10t perpendicular to the axis of the top yoke 10t.

[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 bottom surfaces Sa and Sb perpendicular to the axis Ca of the octagonal 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.

[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 bottom surfaces Sa and Sb perpendicular to the axis Ca of the cylinder 10tc. 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. The octagonal prism 10tp, which shares the same axis Ca as the cylinder 10tc, is sandwiched between the two cylinders 10tc, which are separated 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 side surfaces. That is, the two contact surfaces Sc are formed on the flat side surfaces of the octagonal prism 10tp which is included in a 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, which is 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 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 side surfaces. That is, the two contact surfaces Sc are formed on the flat side surfaces of the octagonal prism 10tp which is included in a portion of the top yoke 10t.

[0091] The bottom surface Sa of the top yoke 10t, which forms a 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 has an attractive force, the magnetic fluxes Ba and Bb (see Figure 1B) pass through the bottom surface Sa of the top yoke 10t, which forms a part of the attractive 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 attractive force of the permanent electromagnet device 10. In other words, it is preferable for the bottom surface Sa to be circular, as shown in Figures 12C and 12D, rather than polygonal, as shown in Figures 12A and 12B.

[0093] Furthermore, a cover can 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 the present 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 the end (10p) of the second permanent magnet that is closer to the magnetic material (W) that can be attracted by the permanent electromagnet device, of the two ends of the second permanent magnet that extend along the magnetization direction. 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 the plurality of top yokes, the total area of ​​the contact surfaces (Sc, Sce) of the top yokes with the first permanent magnets in contact with the top yokes 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 Note 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 adsorption force on the adsorption surface can be suppressed.

[0097] (Note 3) In the permanent electromagnet device described in Note 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 Note 1, the contact surfaces of the top yokes that contact the first permanent magnet may be rectangles of the same 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 Note 2, each of the multiple top yokes may be in contact with the two first permanent magnets. With this configuration, variations in the adsorption force on the adsorption surface can be suppressed.

[0100] (Note 6) In the permanent electromagnet device described in Note 1, 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 may be 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.

Claims

1. A permanent electromagnet device (10) comprising: a plurality of first permanent magnets (10a); a plurality of second permanent magnets (10b) arranged in a grid pattern; a coil (10c) 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 when an electric current flows through it; 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, wherein each of the plurality of first permanent magnets is positioned between two adjacent top yokes, and one of the two top yokes abuts against one end (10s) of the first permanent magnet where one magnetic pole is formed, and the other end (10n) of the first permanent magnet where the other magnetic pole is formed abuts against the other top yoke. A permanent electromagnet device in which, in multiple top yokes, the total area of ​​the contact surfaces (Sc, Sce) of the top yokes with the first permanent magnet that the top yokes contact is the same.

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

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

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

6. A permanent electromagnet device according to claim 1, wherein the top yoke has a three-dimensional shape that is in contact with the end of the second permanent magnet covered by the top yoke, 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.

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