Multilayer magnets and motors

Abstract

This invention provides a technology for stacked magnets that improves strength while increasing residual magnetic flux density. [Solution] The stacked magnet comprises a plurality of stacked magnets, an insulating portion made of an insulating material and positioned between adjacent magnets among the plurality of magnets, and a magnetic portion made of a magnetic material and positioned together with the insulating portion between adjacent magnets, the magnetic portion being in contact with each of the adjacent magnets.

Description

Technical Field

[0001] The present invention relates to a laminated magnet and a motor.

Background Art

[0002] Conventionally, a laminated magnet in which a plurality of magnets are laminated has been known (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, even with the prior art such as Patent Document 1, there is still room for improvement in the technology of improving the strength while improving the residual magnetic flux density in the laminated magnet.

[0005] An object of the present invention is to provide a technology for improving the strength while improving the residual magnetic flux density in a laminated magnet.

Means for Solving the Problems

[0006] The present invention has been made to solve at least a part of the above-described problems and can be realized in the following forms.

[0007] (1) According to one aspect of the present invention, a laminated magnet is provided. This laminated magnet includes a plurality of laminated magnets, an insulating portion disposed between adjacent magnets among the plurality of magnets and formed of an insulating material, and a magnetic portion disposed between the adjacent magnets together with the insulating portion and formed of a magnetic material, the magnetic portion being in contact with each of the adjacent magnets.

[0008] In this configuration, an insulating portion made of an insulating material and a magnetic portion made of a magnetic material are arranged between adjacent magnets among the multiple magnets. This increases the volume ratio of the magnetic portion in the laminated magnet, thereby improving the residual magnetic flux density. Furthermore, since the magnetic portion is in contact with each adjacent magnet, adjacent magnets can be connected relatively strongly. In this way, the flexural strength of the laminated magnet can be increased while improving the residual magnetic flux density.

[0009] (2) In the stacked magnet of the above form, in the cross section in the stacking direction of the plurality of magnets, the ratio of the sum of the lengths of the boundaries between the magnetic portion and each of the adjacent magnets to the sum of the lengths of the surfaces of the adjacent magnets may be 10% or more and 40% or less. With this configuration, in the cross section in the stacking direction of the plurality of magnets, the ratio of the sum of the lengths of the boundaries between the magnetic portion and each of the adjacent magnets to the sum of the lengths of the surfaces of the adjacent magnets is 10% or more and 40% or less. This makes it possible to reduce eddy current losses through the magnetic portion while simultaneously improving residual magnetic flux density and increasing flexural strength.

[0010] (3) In the laminated magnet of the above form, the magnetic part may be formed of the same type of magnetic material as the material forming each of the plurality of magnets. With this configuration, the magnetic part is integrated with the magnet. This makes it possible to further improve the flexural strength of the laminated magnet.

[0011] (4) In the stacked magnet of the above form, the maximum thickness of the insulating portion in the stacking direction of the plurality of magnets may be 10 μm or less. With this configuration, the proportion of magnets and magnetic parts made of magnetic material in the stacked magnet becomes even larger. This makes it possible to further improve the residual magnetic flux density.

[0012] (5) According to another embodiment of the present invention, a motor is provided. This motor comprises a rotor having the above-described laminated magnets and a stator having coils. In this configuration, the rotor of the motor has laminated magnets in which an insulating portion formed of an insulating material and a magnetic portion formed of a magnetic material are arranged between adjacent magnets. This makes it possible to improve the residual magnetic flux density in the laminated magnets, thereby making it possible to increase the output of the motor relatively large and to suppress the occurrence of malfunctions due to damage to the laminated magnets.

[0013] Furthermore, the present invention can be realized in various forms, for example, in the form of a method for manufacturing a stacked magnet, a method for manufacturing the insulating part and the magnetic part of a stacked magnet, an apparatus including a stacked magnet, a method for manufacturing an apparatus including a stacked magnet, and a method for controlling an apparatus including a stacked magnet. [Brief explanation of the drawing]

[0014] [Figure 1] This is a perspective view of the laminated magnet according to the first embodiment. [Figure 2] This is a cross-sectional view of the stacked magnet according to the first embodiment. [Figure 3] This is a cross-sectional view of a motor equipped with a stacked magnet according to the first embodiment. [Figure 4] This is a cross-sectional view of a rotor equipped with a stacked magnet according to the first embodiment. [Figure 5] This is a schematic diagram of an enlarged cross-section of the stacked magnet of the first embodiment. [Figure 6] This is the first figure illustrating the method for calculating the ratio of the length of the magnetic part. [Figure 7] This is the second figure illustrating the method for calculating the ratio of the length of the magnetic part. [Figure 8] This is the first figure illustrating the results of an evaluation test of a stacked magnet according to the first embodiment. [Figure 9] This is the second figure illustrating the results of an evaluation test of the stacked magnet according to the first embodiment. [Figure 10] This is the third figure illustrating the results of an evaluation test of the stacked magnet according to the first embodiment. [Figure 11] It is a perspective view of a modified example of the laminated magnet of the first embodiment.

Mode for Carrying Out the Invention

[0015] <First Embodiment> FIG. 1 is a perspective view of the laminated magnet 10 of the present embodiment. FIG. 2 is a cross-sectional view of the laminated magnet 10 of the present embodiment. FIG. 3 is a cross-sectional view of the motor 100 including the laminated magnet 10 of the present embodiment. FIG. 4 is a cross-sectional view of the rotor 110 including the laminated magnet 10 of the present embodiment. The laminated magnet 10 of the present embodiment is used in a motor 100 that generates rotational torque by electricity supplied from an external power source not shown. As shown in FIG. 1, the laminated magnet 10 includes a plurality of magnets 11 that are laminated and an intermediate layer 12. Note that the technical field in which the laminated magnet 10 of the present embodiment is used is not limited to motors.

[0016] The motor 100 of the present embodiment includes a rotor 110, a stator 120, and a motor case 130. The rotor 110 includes a rotor member 110a having a substantially cylindrical shape and the laminated magnet 10. In the motor 100 of the present embodiment, the laminated magnet 10 is provided on the rotor 110 such that the lamination direction of the plurality of magnets 11 in the laminated magnet 10 is parallel to the rotation axis C1 of the rotor 110 in the motor 100 (see FIG. 3). The laminated magnet 10 is inserted into an insertion hole 110b formed in the rotor 110.

[0017] Magnet 11 contains rare earth elements. Examples of rare earth elements include one or more selected from the group consisting of neodymium (Nd), praseodymium (Pr), terbium (Tb), dysprosium (Dy), samarium (Sm), yttrium (Y), scandium (Sc), lanthanum (La), cerium (Ce), europium (Eu), gadolinium (Gd), holmium (Ho), ytterbium (Yb), and lutetium (Lu). Among these, it is desirable that the magnet contains one or more of Nd, Pr, Dy, and Tb as rare earth elements, and it is more desirable that it contains Nd as the main component. Note that "containing Nd as the main component" means that the Nd content (mass%) is the highest among the rare earth elements contained in magnet 11. In addition to rare earth elements, magnet 11 may also contain transition metal elements and boron. In the stacked magnet 10 of this embodiment, the magnetization directions of the multiple stacked magnets 11 are arranged parallel to each other, for example, in the x-axis direction in the perspective view of the stacked magnet 10 shown in Figure 1.

[0018] The intermediate layer 12 is placed between adjacent magnets 11 among the multiple magnets 11. The intermediate layer 12 has an insulating portion formed of an insulating material and a magnetic portion formed of a magnetic material.

[0019] Figure 5 is a schematic enlarged cross-sectional view of the stacked magnet 10 of this embodiment. As shown in Figure 5, the intermediate layer 12 has an insulating portion 121 formed of an insulating material and a magnetic portion 122 formed of a magnetic material. The insulating portion 121 is placed between adjacent magnets 11 among the plurality of magnets 11 and is formed of an insulating material. In this embodiment, the insulating portion 121 is formed of ceramics. It is desirable that the insulating portion 121 contains one or more selected from the group consisting of CaF2, BaF2, SrF2, MgF2, Al2O3, ZrO2, Dy2O3, Tb2O3, Nd2O3, TbF3, DyF3, LiF, SiO2, BN, ZrB2, Si3N4, TiB2, Pr2O3, and SiC. It is desirable that the insulating portion 121 contains at least a fluoride of group 2A of the periodic table. It is more desirable that the insulating portion 121 contains at least one selected from the group consisting of CaF2, BaF2, SrF2, and MgF2 as a fluoride of Group 2A of the periodic table. The insulating portion 121 of this embodiment contains CaF2. The maximum thickness d121 of the insulating portion 121 of this embodiment is 10 μm or less. The thickness d121 of the insulating portion 121 of this embodiment is 10 μm. It is desirable that the thickness d121 of the insulating portion 121 be 30 μm or less. The thickness d121 of the insulating portion 121 can be, for example, 1 μm or more.

[0020] The magnetic portion 122 is positioned together with the insulating portion 121 between adjacent magnets 11 and is made of a magnetic material. The magnetic portion 122 is in contact with each of the adjacent magnets 11. In this embodiment, the magnetic portion 122 is made of the same type of magnetic material as the material forming each of the multiple magnets 11. As a result, the magnetic portion 122 is integrated with each of the adjacent magnets 11.

[0021] In the stacked magnet 10 of this embodiment, the ratio of the total length of the boundary between the magnetic part 122 and each adjacent magnet 11 to the total length of the respective surfaces of adjacent magnets 11 (hereinafter simply referred to as "the ratio of the length of the magnetic part") is 10% or more and 40% or less. Here, the "total length of the respective surfaces of adjacent magnets 11" and the "total length of the boundary between the magnetic part 122 and each adjacent magnet 11" will be explained using Figure 5. In Figure 5, if the "adjacent magnets 11" are magnets 111 and 112, then magnet 111 has a surface S111 that is in contact with the intermediate layer 12, and magnet 112 has a surface S112 that is in contact with the intermediate layer 12. Therefore, the "total length of the respective surfaces of adjacent magnets 11" is the length (L11 × 2). The "sum of the lengths of the boundaries between the magnetic part 122 and each adjacent magnet 11" is the sum of the length of the portion on the surface S111 of magnet 111 where the magnetic part 122 and magnet 111 are in contact, and the length of the portion on the surface S112 of magnet 112 where the magnetic part 122 and magnet 112 are in contact. Specifically, the sum of the lengths of the portions on the surface S111 of magnet 111 where the magnetic part 122 and magnet 111 are in contact is the sum of lengths La, Lb, and Lc, and the sum of the lengths of the portions on the surface S112 of magnet 112 where the magnetic part 122 and magnet 112 are in contact is the sum of lengths Ld, Le, and Lf. Therefore, in Figure 5, the "sum of the lengths of the boundaries between the magnetic part 122 and each adjacent magnet 11" is (La + Lb + Lc + Ld + Le + Lf). Thus, the ratio Ra (%) of the length of the magnetic part 122 in this embodiment is expressed by the following formula (1). It is more desirable that the ratio Ra of the length of the magnetic portion 122 is between 20% and 30%. In this embodiment, when the surface length L11 of the magnet 11 is 60 μm, the ratio Ra of the length of the magnetic portion 122 is 20.0%. Ra=(La+Lb+Lc+Ld+Le+Lf) / (L11×2)×100...(1)

[0022] The ratio Ra of the length of the magnetic portion 122 in the stacked magnet 10 is calculated using a cross-sectional image of the stacked magnet 10 (magnification: 2000x) taken with a scanning electron microscope (SEM). Here, we will specifically explain one example of how to calculate the ratio Ra of the length of the magnetic portion using a cross-sectional image of a stacked magnet taken with an SEM.

[0023] Figure 6 is the first diagram illustrating a method for calculating the ratio of the length of the magnetic part. Figure 6(a) shows an actual cross-sectional photograph Im1 of a stacked magnet 10 taken using an SEM. In the method for calculating the ratio Ra of the length of the magnetic part, first, a first image processing is performed to set the contrast of the cross-sectional photograph to 100%. Figure 6(b) is a processed image Im2 obtained by applying the first image processing to the cross-sectional photograph in Figure 6(a). Next, using the image processing software ImageJ, a second image processing is performed to change the color type of the image that has undergone the first image processing to 8 bits and to set a threshold, thereby separating the part corresponding to the magnet or magnetic part and the part corresponding to the insulating part into white and black, respectively. In addition, in the second image processing, in order to determine the rough outline of the part corresponding to the insulating part, for example, binary median processing is performed using the image processing software ImageJ, and black parts that are not recognized as corresponding to the insulating part are removed. Here, "black areas that are not considered to correspond to the insulating area" refers, for example, to black areas located away from the black band-shaped area B121 ("the area corresponding to the insulating area") in the center of the processed image Im2. In the second image processing, these image processing steps are performed on the processed image Im2 to create a processed image Im3 in which the area P121 corresponding to the insulating area is shown in black. In creating the processed image Im3, the Binary Median processing described above is performed with the value of "Radius," one of the setting items, set to, for example, 3.

[0024] Figure 7 is the second diagram illustrating the method for calculating the ratio of the length of the magnetic part. Figure 7 shows the processed image Im3 shown as Figure 6(c). In the method for calculating the ratio of the length of the magnetic part, the part corresponding to the insulating part is divided into multiple regions. Specifically, in the processed image Im3 shown in Figure 7, 20 regions A01 to A20 are arranged along a direction perpendicular to the stacking direction D10 of the multiple magnets 11 in the stacked magnet 10. Note that the number of regions to be divided is not limited to this. Next, among the multiple regions, conductive regions that connect the parts corresponding to adjacent magnets and divided regions adjacent to the conductive regions are set. Specifically, using the enlarged view Im31 of the part enclosed by the rectangular frame F1 in the processed image Im3 shown in Figure 7, of the regions A05, A06, and A07 included in the enlarged view Im31, region A06 is the conductive region, and regions A05 and A07 are the divided regions.

[0025] In the method for calculating the ratio of the length of the magnetic part, the next step is to focus on the parts corresponding to the two insulating parts that sandwich the part connecting the parts corresponding to adjacent magnets in the conductive region, and for each of the two insulating parts, determine the point located on the one side in the stacking direction and the point located on the other side in the stacking direction. Specifically, in the enlarged view Im31 of Figure 7, if the parts P121 corresponding to the two insulating parts that sandwich the part connecting the parts corresponding to adjacent magnets are called insulating parts P121a and P121b, then in insulating part P121a, the point located on the one side in the stacking direction D10 is point Pa1, and the point located on the other side in the stacking direction D10 is point Pa2. In insulating part P121b, the point located on the one side in the stacking direction D10 is point Pb1, and the point located on the other side in the stacking direction D10 is point Pb2.

[0026] In the method for calculating the ratio of the length of the magnetic part, the first step is to determine a virtual line connecting the points on the furthest side of the stacking direction of the laminated magnet in each of the two insulating parts, and a virtual line connecting the points on the furthest side of the stacking direction of the laminated magnet in each of the two insulating parts. Specifically, as shown in the enlarged view Im31 of Figure 7, a virtual line VL1 is determined connecting point Pa1 in insulating part P121a and point Pb1 in insulating part P121b, and a virtual line VL2 is determined connecting point Pa2 in insulating part P121a and point Pb2 in insulating part P121b. Next, the part enclosed by the parts corresponding to the two insulating parts and the two virtual lines is defined as the magnetic part. In the enlarged view Im31 of Figure 7, the part enclosed by the two insulating parts P121a and P121b and the two virtual lines VL1 and VL2 is the magnetic part P122 (indicated by dot hatching in the enlarged view Im31 of Figure 7).

[0027] In the method for calculating the ratio of the length of the magnetic part, the next step is to measure the number of regions that contain the magnetic part. At this time, the number of regions containing the magnetic part on one side of the stacking direction and the number of regions containing the magnetic part on the other side of the stacking direction are counted. In the enlarged view Im31 of Figure 7, the magnetic part P121 is contained in regions A05 and A06 on one side of the stacking direction D10, and in region A06 on the other side of the stacking direction D10. That is, in the enlarged view Im31 of Figure 7, the "number of regions containing the magnetic part" is 3. In the processed image Im3 of Figure 7, the "regions containing the magnetic parts" are regions A05, A06, A09, A18, A19, and A20 on one side of the stacking direction, and regions A06, A09, A10, A19, and A20 on the other side of the stacking direction. Therefore, the "number of regions containing the magnetic parts" is 11. Finally, by calculating the ratio of the number of regions containing the magnetic parts to the number of regions on one side and the other side of the stacking direction in each of the multiple regions, the ratio of the length of the magnetic part to the length of the boundary between the magnetic part and each adjacent magnet (the ratio of the length of the magnetic part) can be obtained. In the processed image Im3 of Figure 7, the number of regions on one side and the other side of the stacking direction in each of the 20 regions A01 to A20 is 40. Therefore, the "ratio of the length of the magnetic part 122 Ra" is 11 / 40 × 100 = 27.5%. In this way, by defining the magnetic parts and calculating the ratio of the number of regions containing the defined magnetic parts, the ratio of the length of the magnetic parts can be easily calculated.

[0028] The stator 120 has a stator core 120a and a coil 120b. The stator 120 is located outside the rotor 110 and is fixed to the motor case 130 inside the motor case 130, which will be described later. The stator core 120a is formed to have a substantially cylindrical shape and has a plurality of protrusions 120c on its inside. The coil 120b is a conductive wire covered with an insulator and is wound around each of the plurality of protrusions 120c on the stator core 120a. When electricity supplied from outside the motor 100 flows through the coil 120b, it generates a magnetic field.

[0029] The motor case 130 is a hollow component that houses the rotor 110 and the stator 120 inside. The motor case 130 is provided with two bearings 130a and 130b. The two bearings 130a and 130b rotatably support the rotor 110.

[0030] Next, the manufacturing method of the stacked magnet 10 of this embodiment will be described. In the manufacturing of the stacked magnet 10, first, a strip-cast alloy (SC alloy) powder is prepared (preparation step). In this embodiment, the composition of the SC alloy is Nd2Fe 14 This is represented by B. SC alloys are prepared by mixing the main raw materials of Nd / Pr alloys, alloys containing Co, Al, Cu, Ga, and Zr, and elemental metals, under an argon atmosphere. Next, the SC alloy is subjected to hydrogen absorption using a hydrogen furnace (hydrogen atmosphere, temperature: 200°C, time: 2 hours) to embrittle the grain boundaries (neodymium-rich phase) of the SC alloy (hydrogen decomposition process), thereby producing SC alloy powder.

[0031] Following the hydrogenation process, a lubricant is added to the SC alloy powder (first lubricant addition step). Methyl caprylate is used as the lubricant. The mixing ratio of the lubricant to the amount of SC alloy is, for example, 0.03% to 0.07% by mass. Specifically, the SC alloy powder is coarsely ground under a nitrogen or argon atmosphere while adding the lubricant using a stirrer (coarse grinding step). The average particle size D50 of the SC alloy powder after coarse grinding is, for example, 50 μm to 500 μm.

[0032] Following the coarse grinding process, the coarsely ground SC alloy powder is finely ground using a jet mill under a nitrogen atmosphere while adding a lubricant (fine grinding process). The average particle size D50 after fine grinding is, for example, 2.0 μm to 3.5 μm. Next, a lubricant is added to the finely ground SC alloy powder (second lubricant addition process). Methyl laurate is used as the lubricant. The mixing ratio of the lubricant to the amount of SC alloy is, for example, 0.05 mass% to 0.1 mass%.

[0033] Following the second lubricant addition step, SC alloy powder is filled into each of the multiple molding spaces of a mold equipped with multiple partition plates in a nitrogen atmosphere (powder filling step). Each of the multiple molded bodies formed in each of the multiple molding spaces corresponds to the magnets that will be stacked in the temporary fixing step described later. After the powder filling step, an external magnetic field of, for example, 2T to 4T (Tesla) is applied to the mold filled with SC alloy powder in the planar direction (perpendicular to the thickness direction) of each of the multiple molded bodies to align the orientation of the SC alloy powder (orientation step). Next, the SC alloy powder filled in the mold is pressurized to form the SC alloy molded body (molding step). The conditions for pressurized molding in the molding step are, for example, a pressure of 5MPa to 20MPa and a filling density of 3.0g / cm³. 3 ~4.0g / cm 3 The relative density is 40% to 52%.

[0034] Following the molding process, the outer frame is removed from the mold, and the fired product, in which the molded body and partition plates are alternately connected, is removed (removal process). The fired product, including the partition plates, is heated in an argon atmosphere at a temperature of 500°C for 3 to 4 hours to dehydrogenate it. The dehydrogenated fired product, including the partition plates, is held at a temperature of 930°C to 1050°C for 3 hours and fired in a vacuum atmosphere (first firing process). This produces the magnet 11.

[0035] Following the first firing process, the partition plate is removed from the manufactured magnet 11, and the raw material for the insulating part 121 is applied to the surface of the magnet 11 before lamination (insulating part application process). A mixture of CaF2 powder and a solvent is used as the raw material for the insulating part 121. The thickness of the insulating part 121 raw material applied to the surface of the magnet 11 before lamination is 20 μm, which is twice the thickness of the intermediate layer 12 in the laminated magnet 10 (10 μm). The insulating part 121 raw material is applied, for example, by spraying in the atmosphere. However, the method of applying the insulating part 121 raw material to the surface of the magnet 11 is not limited to this.

[0036] Following the insulating coating process, multiple magnets 11 coated with the insulating material 121 are stacked in the atmosphere and temporarily fixed (temporary fixing process). Following the temporary fixing process, the temporarily fixed stack is placed in a hot press mold and subjected to uniaxial hot pressing (hot pressing process). In the hot pressing process, for example, a pressure of 5 × 10 -2 Pa~1×10 -4 The process is carried out under a vacuum atmosphere of approximately Pa, or under an inert atmosphere (such as a nitrogen or argon atmosphere). The hot press temperature is, for example, 700°C to 1100°C, and the hot press press duration is, for example, 1 second to 1 hour. The hot press pressure is, for example, 3 MPa to 100 MPa, and the hot press heat treatment duration is, for example, 3 minutes to 20 hours. In the manufacturing method of the laminated magnet 10 of this embodiment, during such a hot press process, the magnetic material forming the magnet 11 diffuses into the raw material of the insulating part 121, and the magnetic part 122 is formed. The laminated magnet 10 of this embodiment is manufactured in this manner. However, the manufacturing method of the laminated magnet 10 is not limited to this.

[0037] Next, the evaluation test of the laminated magnet in this embodiment will be described. In this evaluation test, multiple laminated magnets with different insulating thicknesses (hereinafter referred to as "samples") were prepared, and the "eddy current loss ratio," "residual magnetic flux density," "flexural strength," and "motor magnet temperature" were measured or calculated for each of the multiple samples.

[0038] Figure 8 is the first diagram illustrating the evaluation results of the laminated magnet of this embodiment. The five types of samples used in this evaluation test were manufactured by a method similar to the manufacturing method of the laminated magnet 10 of this embodiment. Sample 1 is a comparative example sample in this evaluation test and does not have a portion corresponding to the intermediate layer of this embodiment, and has a structure in which multiple magnets are simply stacked. Each of Samples 2 to 4 has an intermediate layer having an insulating portion formed of an insulating material and a magnetic portion formed of a magnetic material, similar to the laminated magnet 10 of this embodiment. The insulating portion of each of Samples 2 to 4 contains CaF2, and the magnetic portion is formed of the same material as the magnet. In Sample 5, the portion corresponding to the intermediate layer of this embodiment does not have a magnetic portion in contact with each of the adjacent magnets, and is composed only of an insulating portion. The size of the magnets in the samples used in this evaluation test is 6 mm in the magnetization direction × 2 mm × 20 mm in the stacking direction, and the size of the portion of the laminated magnet excluding the intermediate layer is 6 mm in the magnetization direction × 40 mm × 20 mm in the stacking direction.

[0039] The "insulating layer thickness (μm)" shown in Figure 8 was calculated from the thickness of the insulating layer material applied during the insulating layer coating process in the preparation of Samples 1 to 5. Specifically, the insulating layer thickness in each sample was calculated based on measured data where the thickness of the insulating layer material applied during the insulating layer coating process was reduced to 0.5 times by hot pressing. Each of Samples 2 to 5, which have an insulating layer, contains CaF2, a ceramic, as the "insulating layer material," as described above.

[0040] Figure 8 shows, for each of Samples 2 to 5, the ratio of the length of the magnetic portion to the length of the boundary between each adjacent magnet 11 and the respective surface length of the adjacent magnets, as the "Percentage of Magnetic Portion Length (%)". The method for calculating the "Percentage of Magnetic Portion Length (%)" is the same as the method for calculating the percentage of magnetic portion length explained using Figures 6 and 7. As mentioned above, Sample 1 does not have a portion corresponding to an intermediate layer. For each of Samples 2 to 5, the "Percentage of Magnetic Portion Length (%)" is between 20% and 27.5%, while for Sample 5, it is 0% because there is no magnetic portion in contact with each adjacent magnet.

[0041] The "Eddy Current Loss Ratio (%)" shown in Figure 8 compares the eddy current losses for each of the samples from Sample 1 to Sample 5. Here, we will explain how the "Eddy Current Loss Ratio (%)" shown in Figure 8 was calculated. First, each of the samples from Sample 1 to Sample 5 was placed between the magnetic poles of a C-type core, and the eddy current loss was measured using a power meter under conditions of 25°C, 1kHz frequency, and 0.01T magnetic flux density. Next, using the measured eddy current losses for each of the samples from Sample 1 to Sample 5, the ratio of the measured eddy current losses for each of the samples from Sample 2 to Sample 5 was calculated, with the measured eddy current loss for Sample 1 set to 100. As shown in Figure 8, the "Eddy Current Loss Ratio (%)" for all of the samples from Sample 2 to Sample 5 is smaller than that for Sample 1.

[0042] Figure 8 shows the "Residual Magnetic Flux Density (T)" for each of Samples 1 to 5, comparing their residual magnetic flux densities. Here, we will explain the method for calculating the "Residual Magnetic Flux Density (T)" shown in Figure 8. In this method, the residual magnetic flux densities of Sample 1, with an insulation thickness of 0 μm, and Sample 5, with an insulation thickness of 25.0 μm, were measured using a Teslameter (Gaussmeter). Next, for Samples 2 to 4, whose insulation thicknesses range from 0 μm to 25.0 μm, the residual magnetic flux densities for each of Samples 2 to 4 were calculated using the one-to-one relationship between the insulation thickness and the residual magnetic flux density. In this evaluation test, the "Residual Magnetic Flux Density (T)" scores were set as follows, according to the magnitude of the calculated (measured) values ​​of the residual magnetic flux density. 1.40T: 5 points 1.38T or more and less than 1.40T: 3 points 1.37T or higher and less than 1.38T: 1 point Less than 1.37T: 0 points

[0043] Figure 8 shows the "Flexural Strength (MPa)" for each of the stacked magnets, comparing their overall strength. For each of the samples from 1 to 5, a three-point bending test was performed, and the bending stress value was calculated based on the maximum load until the sample broke. In this evaluation test, the "Flexural Strength (MPa)" score was set for each of the samples from 1 to 5 according to the magnitude of the calculated bending stress, as follows. Note that in the "Flexural Strength (MPa)" score, it was assumed that the repulsive force between magnets generated during magnetization in the sample manufacturing process would be 10 MPa, so a score of 1 or more was set for 10 MPa or higher. 60MPa or more: 5 points 30 MPa to less than 60 MPa: 3 points 10 MPa to less than 30 MPa: 1 point Less than 10 MPa: 0 points

[0044] Figure 8 shows the "Motor Magnet Temperature (°C)" for Sample 1 and Sample 5, respectively, representing the calculated (measured) temperature of the samples when used as motor magnets under the same conditions. Here, we will explain the method (measurement method) for calculating the "Motor Magnet Temperature (°C)" shown in Figure 6. In the method (measurement method) for calculating the "Motor Magnet Temperature (°C)," first, a motor with Sample 1 (eddy current loss ratio of 100%) and Sample 5 (eddy current loss ratio of 73%) set on its rotor was driven for 200 hours at a maximum torque of 500 N·m and a maximum rotational speed of 10,000 rpm. After that, the surface temperature of the samples was measured by observing the surface of the samples with a laser. Next, for each of Samples 2 to 4, whose eddy current loss ratios fall within the range of 73% to 100%, the motor magnet temperature of each of Samples 2 to 4 was calculated using the one-to-one correspondence between the eddy current loss ratio and the motor magnet temperature. In this evaluation test, for each of Samples 1 to 5, the score for "Motor Magnet Temperature (°C)" was set as follows, according to the magnitude of the calculated (measured) value of "Motor Magnet Temperature (°C)". Note that the score for "Motor Magnet Temperature (°C)", which is intended for use in motors, the primary application of multilayer magnets, is set higher than the score for "Residual Magnetic Flux Density (T)" mentioned above. Below 60℃: 8 points 60℃ or higher but less than 70℃: 5 points 70°C to less than 75°C: 3 points 75℃ or higher: 0 points

[0045] The "Overall Evaluation" shown in Figure 8 was determined for each of Samples 2 to 5 using the sum of the scores for "Residual Magnetic Flux Density (T)", "Flexural Strength (MPa)", and "Motor Magnet Temperature (°C)". In this evaluation test, for each of Samples 2 to 5, the "Overall Evaluation" was grouped as follows, according to the magnitude of the sum of the scores for "Residual Magnetic Flux Density (T)", "Flexural Strength (MPa)", and "Motor Magnet Temperature (°C)". The total score for Sample 1, which is a comparative example, is 10 points. 12 points or more: A 11 points:B 10 points or less: C

[0046] From the "Remanent Magnetic Flux Density (T)" shown in Figure 8, it was confirmed that the "Percentage of Magnetic Part Length (%)" for sample 2 (27.5%) and samples 3 and 4 (20.0%) were all greater than that of sample 5, where the "Percentage of Magnetic Part Length (%)" was 0%, meaning the portion corresponding to the intermediate layer consisted only of insulating material. Furthermore, the difference between the remanent magnetic flux densities of samples 2 to 4 and those of sample 1, which lacks an intermediate layer, was within the tolerance of the Teslameter used for measurement (±0.03(T)), confirming that the remanent magnetic flux densities of samples 2 to 4 were approximately the same as those of sample 1. In addition, from the "Flexural Strength (MPa)" shown in Figure 8, it was confirmed that the "Percentage of Magnetic Part Length (%)" was greater than 0%, meaning that samples 2 to 4, which have a magnetic portion corresponding to the intermediate layer, were significantly greater than that of sample 5, which does not have a magnetic portion corresponding to the intermediate layer. These findings confirm that the presence of a magnetic region in the intermediate layer improves both the residual magnetic flux density and the flexural strength.

[0047] As shown in Figure 8, the "Motor Magnet Temperature (°C)" for each of the samples from 2 to 4 was found to be lower than that of sample 1. In particular, for samples 3 and 4, where the "Percentage of Magnetic Part Length (%)" was 20.0%, the "Motor Magnet Temperature (°C)" was found to be significantly lower than that of sample 1. These results suggest that when the percentage of magnetic part length is between 10% and 40%, the temperature of the laminated magnet used in the motor decreases significantly.

[0048] As shown in the "Overall Evaluation" in Figure 8, it was confirmed that each of the samples from 2 to 4 exhibited superior characteristics compared to the comparative examples, Sample 1 and Sample 5. As a result, when the laminated magnets of Samples 2 to 4 are used in a motor, the residual magnetic flux density is improved compared to when the laminated magnet of Sample 5, which lacks a magnetic portion in the intermediate layer, is used, allowing for a higher motor output. Furthermore, when the laminated magnets of Samples 2 to 4 are used in a motor, the flexural strength of the laminated magnet is significantly improved, thus suppressing motor malfunctions caused by damage to the laminated magnet.

[0049] As shown in the "Overall Evaluation" in Figure 8, among samples 2 to 4, samples 3 and 4 were confirmed to exhibit superior characteristics compared to sample 1. In particular, samples 3 and 4 were confirmed to have the characteristic of significantly reducing the motor magnet temperature while maintaining almost no change in residual magnetic flux density. As a result, when the stacked magnets of samples 3 and 4 are used in a motor, the motor temperature rise can be suppressed, allowing for an even higher motor output.

[0050] Figure 9 is a second figure illustrating the results of the evaluation test of the stacked magnet of the first embodiment. Figure 9 shows the relationship between the film thickness of the portion corresponding to the intermediate layer ("film thickness of the intermediate layer (μm)") and the eddy current loss ratio ("eddy current loss ratio (%)") for each of several samples, including samples 1 to 5 shown in Figure 8. In Figure 9, similar to the "eddy current loss ratio (%)" shown in Figure 8, the eddy current loss in sample 1, where the film thickness of the portion corresponding to the intermediate layer is 0 μm, i.e., sample 1 does not have a portion corresponding to an intermediate layer, is set to 100%, and the "eddy current loss ratio (%)" for several samples is shown. As shown in Figure 9, it was confirmed that the eddy current loss ratio of the samples decreases as the film thickness of the portion corresponding to the intermediate layer, which is the same as the thickness of the insulating part, increases, and it was confirmed that even when the film thickness of the portion corresponding to the intermediate layer is 25 μm, the eddy current loss ratio is smaller than that of sample 1. From this, it can be said that in terms of reducing eddy current loss, it is desirable that the film thickness of the portion corresponding to the intermediate layer, i.e., the thickness of the insulating part, be 25 μm or less.

[0051] As shown in Figure 9, the eddy current loss ratio of the sample gradually decreases until the film thickness of the intermediate layer reaches approximately 10 μm, but it was confirmed that the eddy current loss ratio does not change significantly even when the film thickness of the intermediate layer exceeds 10 μm. In terms of improving the residual magnetic flux density in a laminated magnet, it is desirable for the proportion of the volume of the laminated magnet to be occupied by the magnet and magnetic parts formed by the magnetic material to be large. Therefore, in terms of reducing eddy current loss, it is more desirable for the film thickness of the intermediate layer to be 10 μm or less.

[0052] Figure 10 is the third figure illustrating the results of the evaluation test of the laminated magnet of the first embodiment. Figure 10 shows the relationship between the film thickness of the portion corresponding to the intermediate layer ("Intermediate layer film thickness (μm)") and the flexural strength ("Flexural strength (MPa)") for each of several samples, including samples 1 to 5 shown in Figure 8. The "Flexural strength (MPa)" shown in Figure 10 represents the bending stress value calculated based on the maximum load until the sample breaks by performing a three-point bending test, similar to that shown in Figure 8. As shown in Figure 10, when the thickness of the portion corresponding to the film thickness of the intermediate layer, i.e., the insulating portion, is 10 μm or less, the flexural strength of the laminated magnet is 20 MPa or more. Therefore, in terms of increasing flexural strength, it is desirable that the thickness of the insulating portion be 10 μm or less.

[0053] As described above, in the laminated magnet 10 of this embodiment, an insulating portion 121 made of an insulating material and a magnetic portion 122 made of a magnetic material are arranged between adjacent magnets 111 and 112 among the multiple magnets 11. This increases the volume ratio of the magnetic portion 122 in the laminated magnet 10, thereby improving the residual magnetic flux density in the laminated magnet 10. Furthermore, since the magnetic portion 122 is in contact with each of the adjacent magnets 111 and 112, adjacent magnets 11 can be connected to each other relatively strongly. As a result, the flexural strength of the laminated magnet 10 can be increased relatively while improving the residual magnetic flux density.

[0054] Furthermore, in the stacked magnet 10 of this embodiment, in the cross-section in the stacking direction of the multiple magnets 11, the ratio Ra of the length of the boundary between the magnetic part 122 and the adjacent magnets 111 and 112 to the length of the surfaces S111 and S112 of the adjacent magnets 111 and 112 is 10% to 40%. This makes it possible to reduce eddy current losses through the magnetic part 122 while simultaneously improving residual magnetic flux density and increasing flexural strength.

[0055] Furthermore, in the laminated magnet 10 of this embodiment, the magnetic portion 122 is made of the same type of magnetic material as the material that forms each of the multiple magnets 11. As a result, the magnetic portion 122 is integrated with the magnets 11, which further improves the flexural strength of the laminated magnet 10.

[0056] Furthermore, in the laminated magnet 10 of this embodiment, the maximum thickness of the insulating portion 121 in the stacking direction of the multiple magnets 11 is 10 μm or less. As a result, the proportion of magnets 11 and magnetic portions 122 made of magnetic material in the laminated magnet 10 increases. This makes it possible to further improve the residual magnetic flux density.

[0057] Furthermore, according to the motor 100 of this embodiment, the rotor 110 of the motor 100 has a laminated magnet 10 in which an insulating portion 121 formed of an insulating material and a magnetic portion 122 formed of a magnetic material are arranged between adjacent magnets 11. As a result, the residual magnetic flux density in the laminated magnet 10 can be improved, so that the output of the motor 100 can be made relatively large and the occurrence of malfunctions due to damage to the laminated magnet 10 can be suppressed.

[0058] <Modified form of this embodiment> The present invention is not limited to the embodiments described above, and can be implemented in various forms without departing from its spirit, for example, the following modifications are also possible.

[0059] [Example 1] In the above embodiment, the ratio Ra of the length of the magnetic portion 122 in the cross-section in the stacking direction of the multiple magnets 11 was set to be 10% or more and 40% or less. The ratio Ra of the length of the magnetic portion 122 is not limited to this, but if the ratio of the length of the magnetic portion is less than 10%, it becomes difficult to improve the residual magnetic flux density and also difficult to increase the flexural strength. If the ratio of the length of the magnetic portion is greater than 40%, it becomes easier to increase losses due to eddy currents through the magnetic portion. Therefore, by setting the ratio of the length of the magnetic portion to be 10% or more and 40% or less, it is possible to reduce losses due to eddy currents through the magnetic portion while simultaneously improving the residual magnetic flux density and increasing the flexural strength.

[0060] [Differentiation 2] In the embodiment described above, the magnetic portion 122 was assumed to be formed of the same type of magnetic material as the material forming each of the multiple magnets 11. However, the material forming the magnetic portion 122 is not limited to this. It is sufficient if it is made of a magnetic material.

[0061] [Difference 3] In the above-described embodiment, the maximum thickness of the insulating portion 121 in the stacking direction of the multiple magnets 11 was set to 10 μm or less. However, the thickness of the insulating portion is not limited to this.

[0062] [Differentiation Example 4] In the embodiment described above, the stacked magnet was assumed to be rectangular in shape, as shown in Figure 1. However, the shape of the stacked magnet is not limited to this.

[0063] Figure 11 is a perspective view of a modified example of the laminated magnet 10 of the first embodiment. The laminated magnet 10 shown in Figure 11 has a shape when viewed from the z-axis direction that is the unfolded side of a frustocone. In a laminated magnet 10 of this shape, the intermediate layer 12 placed between adjacent magnets 11 has an insulating portion 121 formed of an insulating material and a magnetic portion 122 formed of a magnetic material that is in contact with each of the adjacent magnets 11. This makes it possible to increase the flexural strength of the laminated magnet while improving the residual magnetic flux density.

[0064] [Difference 5] In the embodiments described above, the stacked magnet was assumed to be applied to an IPM motor. However, the motor to which the stacked magnet is applied is not limited to an IPM motor. It may also be applied to an SPM motor or an axial gap motor.

[0065] The embodiments of this specification have been described above based on the embodiments and modifications described above. The embodiments described above are for the purpose of facilitating understanding of this specification and do not limit it. This specification may be modified and improved without departing from its spirit and the scope of the claims, and equivalents thereof are included in this specification. Furthermore, any technical features that are not described as essential in this specification may be deleted as appropriate.

[0066] <Application Example 1> It is a stacked magnet, Multiple magnets stacked on top of each other, Multiple magnets, An insulating portion is placed between adjacent magnets among the plurality of magnets and is formed of an insulating material, A magnetic portion, formed of a magnetic material and arranged together with the insulating portion between adjacent magnets, is characterized by comprising a magnetic portion that is in contact with each of the adjacent magnets. Stacked magnets. <Application Example 2> The stacked magnet described in Application Example 1, In the cross-section in the stacking direction of the plurality of magnets, The ratio of the sum of the lengths of the boundaries between the magnetic portion and each of the adjacent magnets to the sum of the lengths of the surfaces of the adjacent magnets is characterized in that it is 10% or more and 40% or less. Stacked magnets. <Application Example 3> A stacked magnet as described in Application Example 1 or Application Example 2, The magnetic portion is characterized by being formed from the same type of magnetic material as the material used to form each of the plurality of magnets. Stacked magnets. <Application Example 4> A stacked magnet as described in any one of Application Examples 1 to 3, The maximum thickness of the insulating portion in the stacking direction of the plurality of magnets is 10 μm or less, characterized in that Stacked magnets. <Application Example 5> It is a motor, A rotor having a stacked magnet as described in any one of Application Examples 1 to 4, A stator having a coil, characterized by comprising Motor. [Explanation of symbols]

[0067] 10…Stacked magnets 11,111,112… magnets 110... Rotor 12…Middle class 120...Stata 120b... Coil 121, P121a, P121b... Insulation part 122,P122...Magnetic part d121...Maximum thickness of the insulation layer L11... Surface length of the magnet La, Lb, Lc, Ld, Le, Lf… Length of the boundary between the magnetic part and the magnet Ra...Ratio of the length of the magnetic part S111, S112... Surface of the magnet

Claims

1. It is a stacked magnet, Multiple magnets stacked on top of each other, An insulating portion is placed between adjacent magnets among the plurality of magnets and is formed of an insulating material, A magnetic portion, formed of a magnetic material and arranged together with the insulating portion between adjacent magnets, is characterized by comprising a magnetic portion that is in contact with each of the adjacent magnets. Stacked magnets.

2. A stacked magnet according to claim 1, In the cross-section in the stacking direction of the plurality of magnets, The ratio of the sum of the lengths of the boundaries between the magnetic portion and each of the adjacent magnets to the sum of the lengths of the surfaces of the adjacent magnets is 10% or more and 40% or less. Stacked magnets.

3. A stacked magnet according to claim 1 or claim 2, The magnetic portion is characterized by being formed from the same type of magnetic material as the material used to form each of the plurality of magnets. Stacked magnets.

4. A stacked magnet according to claim 1 or claim 2, The maximum thickness of the insulating portion in the stacking direction of the plurality of magnets is 10 μm or less, characterized in that Stacked magnets.

5. It is a motor, A rotor having a stacked magnet according to claim 1 or claim 2, A stator having a coil, characterized by comprising Motor.

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