Magnetic wedge and rotating electric machine

Abstract

To provide a magnetic wedge having high electrical resistance and bending strength, and a rotating electrical machine employing the same.SOLUTION: This magnetic wedge includes a plurality of Fe-based soft magnetic particles, wherein the plurality of Fe-based soft magnetic particles contain an element M that is more readily oxidized than Fe, and are bound with an oxide phase including the element M.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a magnetic wedge used in a magnetic circuit of a rotating electric machine, and to a rotating electric machine using the magnetic wedge. [Background technology]

[0002] In a typical radial gap type rotating electric machine, the stator (hereinafter referred to as "stator") and rotor are arranged coaxially, and multiple teeth with coils wound around them are arranged at equal intervals in the circumferential direction on the stator around the rotor. Magnetic wedges may also be arranged at the rotor-side tips of the teeth to connect the tips of adjacent teeth. In this case, unlike coil components, the magnetic wedges themselves are used without any coils wound around them.

[0003] By arranging such magnetic wedges, it is possible to magnetically shield the magnetic flux reaching the coil from the rotor, thereby suppressing eddy current loss in the coil. Furthermore, by arranging magnetic wedges, it is possible to smooth the magnetic flux distribution in the gap between the stator and rotor (especially the magnetic flux distribution in the circumferential direction), thereby making the rotor rotate smoothly. In this way, by arranging magnetic wedges, it is possible to create a rotating electric machine with high efficiency and high performance.

[0004] Also, a conventional magnetic wedge made by solidifying iron powder and glass cloth with epoxy resin is known (for example, Patent Document 1). This magnetic wedge increases electrical resistance by isolating the iron powder particles with epoxy resin, and increases strength by dispersing glass cloth.

[0005] Furthermore, a magnetic wedge having a large relative magnetic permeability is known in which Fe—Si alloy powder is solidified with a resin (for example, Patent Document 2). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 62-77030 [Patent Document 2] WO2018 / 008738 publication Summary of the Invention [Problem to be solved by the invention]

[0007] The magnetic wedge is required to have a high relative magnetic permeability to provide good magnetic shielding for the coil, and a high electrical resistance to suppress eddy current loss due to the AC magnetic field of the coil and rotor. In addition, the magnetic wedge placed in the rotating electric machine is required to have a high bending strength because the AC magnetic field applies bending stress to the magnetic wedge.

[0008] In Patent Document 1, the electrical resistivity is 10 3 Ωcm, three-point bending strength 25kgf / mm 2 However, in order to meet the demands for low loss and high reliability, it is desirable to have even higher resistance and strength.

[0009] Furthermore, although the magnetic wedge of Patent Document 2 has a high relative magnetic permeability and good magnetic shielding properties, it has problems with reliability such as bending strength because it is simply alloy powder solidified with resin.

[0010] Therefore, the present invention provides a magnetic wedge with high electrical resistance and bending strength, and a rotating electric machine using the magnetic wedge. [Means for solving the problem]

[0011] The magnetic wedge of the present invention is Granular atomized powder The resin-free material contains a plurality of Fe-based soft magnetic particles, the Fe-based soft magnetic particles being bound together by an oxide phase, and exhibits a mass loss rate of less than 0.1% after 450 hours at 220°C.

[0012] In addition, in the magnetic wedge, Mass loss rate after 240 hours at 290°C is less than 1% It is preferable that there is.

[0013] The magnetic wedge is preferably made of Fe-Al-Cr alloy particles.

[0014] In addition, in the magnetic wedge, The reduction in three-point bending strength when heated from 25°C to 150°C is less than 5% It is preferable.

[0015] A rotating electric machine according to the present invention uses any one of the magnetic wedges described above.

[0016] In addition, the method for manufacturing a magnetic wedge of the present invention includes the steps of mixing Fe-based soft magnetic particles containing element M, which is more easily oxidized than Fe, with a binder to form a mixture, press-molding the mixture to form a compact, and heat-treating the compact to form a compact having a surface oxide phase of the Fe-based soft magnetic particles between the particles that binds the Fe-based soft magnetic particles together. [Effects of the Invention]

[0017] According to the present invention, it is possible to provide a magnetic wedge having high electrical resistance and bending strength, and a rotating electric machine using the magnetic wedge. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a schematic view showing the appearance of a magnetic wedge according to a first embodiment of the present invention. [Figure 2] 1 is an enlarged schematic view of a cross section of a magnetic wedge according to a first embodiment of the present invention. [Figure 3] FIG. 4 is an enlarged schematic view of a cross section of a magnetic wedge according to a second embodiment of the present invention. [Figure 4] FIG. 10 is a schematic diagram of a rotating electric machine according to a third embodiment of the present invention. [Figure 5] FIG. 10 is a schematic diagram of a rotating electric machine that is another example of the third embodiment of the present invention. [Figure 6] FIG. 10 is a schematic diagram of a rotating electric machine as yet another example of the third embodiment of the present invention. [Figure 7] 10 is a process flow of a method for manufacturing a magnetic wedge according to a fourth embodiment of the present invention. [Figure 8] 10 is a process flow of a method for manufacturing a magnetic wedge according to a fifth embodiment of the present invention. [Figure 9]1 is an SEM photograph showing a cross-sectional structure of an example. [Figure 10] 1 is a graph showing DC magnetization curves of an example and a comparative example. [Figure 11] 1 is a graph showing iron loss in an example. [Figure 12] FIG. 2 is a model diagram of a rotating electric machine used in an electromagnetic field analysis. [Figure 13] 10 is a graph showing the results of an electromagnetic field analysis of a rotating electrical machine. [Figure 14] 1 is a graph showing the temperature dependence of three-point bending strength in Examples and Comparative Examples. [Figure 15] 1 is a graph showing the weight loss on heating at 220° C. for Examples and Comparative Examples. [Figure 16] 1 is a graph showing the weight loss on heating at 290° C. for Examples and Comparative Examples. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0020] The magnetic wedge of the present invention has a plurality of Fe-based soft magnetic particles, which contain element M, which is more easily oxidized than Fe, and are bound together by an oxide phase containing element M. As shown in the schematic diagram of FIG. 1, the magnetic wedge 100 has, for example, a rectangular strip shape in cross section. As will be described in a later embodiment, the magnetic wedge 100 is arranged in a rotating electric machine so as to connect the rotor-side tips of the teeth, with the longitudinal direction of the strip parallel to the rotation axis of the rotating electric machine. Therefore, the shape of the magnetic wedge 100 varies depending on the manner of connection with the teeth. The longitudinal ridges may have steps or tapers, or may have notches, and the cross section may be a polygon such as a trapezoid or an irregular shape. The approximate dimensions of the magnetic wedge 100 are, for example, 20 mm to 300 mm in the longitudinal direction, 2 mm to 20 mm in the width direction (magnetic path direction), and 1 mm to 5 mm in thickness.

[0021] (First embodiment) 2 is an enlarged schematic diagram of a cross section of a magnetic wedge 100 of this embodiment. The magnetic wedge 100 is composed of a plurality of Fe-based soft magnetic particles, more specifically, a compact of a plurality of Fe-based soft magnetic particles 1 containing element M, which is more easily oxidized than Fe. The compact has voids 2 between the particles, and a surface oxide phase 3 of the Fe-based soft magnetic particles that binds the Fe-based soft magnetic particles 1 together. This surface oxide phase is an oxide phase containing element M.

[0022] Here, the Fe-based soft magnetic particles 1 are soft magnetic alloy particles having the largest Fe content by mass relative to other elements, and may also contain Co and Ni, provided that the Co and Ni contents do not exceed the Fe content.

[0023] While reducing the particle size of the Fe-based soft magnetic particles 1 is advantageous for reducing eddy current loss generated in the magnetic wedge 100 itself, a small particle size can make the production of the particles itself difficult. Therefore, in a cross-sectional observation image of the magnetic wedge 100, the average maximum diameter of each particle of the Fe-based soft magnetic particles 1 is preferably 0.5 μm or more and 15 μm or less, and more preferably 0.5 μm or more and 8 μm or less. Furthermore, the proportion of particles with a maximum diameter exceeding 40 μm is preferably less than 1.0%.

[0024] The average maximum diameter of each particle of the Fe-based soft magnetic particles 1 referred to here refers to the average value of the maximum diameters of 30 or more particles present within a certain area of ​​the field of view, obtained by polishing the cross section of the magnetic wedge 100 and observing it under a microscope.

[0025] Furthermore, the voids 2 and surface oxide phase 3 are present between the Fe-based soft magnetic particles 1, thereby widening the average particle spacing between the Fe-based soft magnetic particles 1 and increasing the electrical resistance of the magnetic wedge 100. In addition, the relative permeability of the magnetic wedge 100 can be adjusted by adjusting the volume ratio of the voids 2 and the surface oxide phase 3 to the entire magnetic wedge. In other words, the volume ratio of the voids 2 and the surface oxide phase 3 to the entire magnetic wedge and the volume ratio of the Fe-based soft magnetic particles 1 (hereinafter referred to as the space factor) are complementary to each other. Therefore, the relative permeability of the magnetic wedge 100 can be adjusted by adjusting the space factor of the Fe-based soft magnetic particles 1. The space factor is defined as the ratio (relative density) of the density of the magnetic wedge 100 to the true density of the Fe-based soft magnetic particles 1. As will be described in a later embodiment, the space factor can be adjusted by the molding pressure of the mixture or the heat treatment temperature of the molded body.

[0026] The relative permeability is calculated by dividing the magnetic flux density value (unit: T) in an applied magnetic field of 160 kA / m by the magnetic field value (i.e., 160 kA / m) in the DC BH curve of the magnetic wedge 100, and then multiplying it by the vacuum permeability (4π×10 -7 H / m). The relative permeability is the slope of the magnetization curve (so-called minor loop) measured at an excitation level of 1 / 10 or less of the saturation magnetic flux density of the magnetic wedge 100 and at a frequency (including DC) of 1 / 10 or less of the natural resonance frequency of the magnetic wedge 100, divided by the permeability of a vacuum (4π×10 -7 The value μi obtained by dividing the relative permeability by the imaginary part of the magnetic field (H / m) may also be used. The natural resonance frequency is the frequency at which the imaginary part of the relative permeability becomes maximum, and if multiple maximums appear, the one at the lowest frequency is used.

[0027] The higher the relative permeability of the magnetic wedge 100, the greater the magnetic shielding effect and the reduced loss. On the other hand, if the relative permeability is too high, the magnetic flux does not flow from the teeth to the rotor, but shorts between the teeth, resulting in a reduced torque of the rotating electric machine. This effect also depends on the thickness of the magnetic wedge 100; even with a magnetic wedge with a high relative permeability, the magnetic resistance can be adjusted by making it thinner, thereby achieving both reduced loss and increased torque to some extent. Furthermore, if the magnetic wedge 100 is too thick, it will take up space for installing the coil, which is undesirable. Because the magnetic wedge of this embodiment has high strength, it is particularly suitable to make it thin. Therefore, the thickness of the magnetic wedge 100 can be, for example, 3 mm or less.

[0028] To maintain the loss reduction effect of the magnetic shield even when the thickness of the magnetic wedge 100 is 3 mm or less, the relative permeability μ of the magnetic wedge 100 is preferably 4 or more (μi 5 or more), and more preferably 7 or more (μi 10 or more).To achieve this, the space factor of the Fe-based soft magnetic particles 1 in the magnetic wedge 100 is preferably 30% or more, and more preferably 50% or more.

[0029] On the other hand, if the magnetic wedge 100 is made too thin, the load-bearing capacity may decrease, resulting in insufficient strength. From this perspective, the thickness of the magnetic wedge 100 is preferably 0.5 mm or more, and more preferably 1 mm or more. In order to suppress a decrease in torque of a rotating electric machine even when the thickness of the magnetic wedge 100 is 1 mm or more, the relative permeability μ of the magnetic wedge 100 is preferably adjusted to 8.0 or less (μi of 65 or less), more preferably 7.5 or less (μi of 50 or less). And even more preferably 7.0 or less (μi of 35 or less). To achieve this, the space factor of the Fe-based soft magnetic particles 1 in the magnetic wedge 100 is preferably less than 90%, more preferably 85% or less, and even more preferably 80% or less.

[0030] The Fe-based soft magnetic particles 1 are particles containing an element M that is more easily oxidized than Fe. Here, "element M that is more easily oxidized than Fe" refers to an element whose standard Gibbs energy of oxide formation is lower than that of Fe2O3. Any element that satisfies this condition can be selected as element M, but it is preferable to select it from Al, Si, Cr, Zr, and Hf because they have low extreme reactivity and toxicity and are easy to manufacture the magnetic wedge 100 from.

[0031] The inclusion of such element M makes it possible to easily form a good surface oxide phase 3 that firmly bonds the Fe-based soft magnetic particles 1 together. Specifically, by oxidizing a plurality of Fe-based soft magnetic particles 1 after molding, it is possible to easily form a surface oxide phase 3 in which the content of element M is higher than that of the interior of the Fe-based soft magnetic particle 1. In particular, it is preferable to select Al as the element M, as this provides a particularly good surface oxide phase 3.

[0032] Such a surface oxide phase 3 is chemically stable and has high electrical resistance, and forms a strong surface oxide phase by tightly adhering to the Fe-based soft magnetic particles 1. That is, the Fe-based soft magnetic particles 1 are separated from each other to form magnetic wedges 100 with high electrical resistance, and the Fe-based soft magnetic particles 1 are firmly bound together to form magnetic wedges 100 with high bending strength.

[0033] Here, the higher the electrical resistance of the magnetic wedge 100, the better, and the volume resistivity value is preferably 10 Ω·m or more, more preferably 20 Ω·m or more, even more preferably 100 Ω·m or more, and even more preferably 1000 Ω·m or more. Furthermore, the higher the bending strength of the magnetic wedge 100, the better, and the three-point bending strength value is preferably 150 MPa or more, more preferably 200 MPa or more, and even more preferably 250 MPa or more.

[0034] Here, if the thickness of the surface oxide phase 3 is too thin, the electrical isolation between the particles will be reduced, reducing the electrical resistance of the magnetic wedge 100 and increasing the relative permeability, which may make it impossible to adjust the relative permeability to a desired value simply by adjusting the volume fraction of the voids 2. On the other hand, if the thickness is too thick, the relative permeability will be reduced and the magnetic shielding effect may be weakened. Therefore, the thickness of the surface oxide phase 3 is preferably set to, for example, 0.01 to 1.0 μm. This makes it possible to obtain a magnetic wedge 100 with high electrical resistance and bending strength and adjusted relative permeability.

[0035] Furthermore, if the amount of element M contained in the Fe-based soft magnetic particles 1 is too small, even if the Fe-based soft magnetic particles 1 are oxidized, it will be difficult to form a good surface oxide phase 3 in which the content of element M is higher than that inside the Fe-based soft magnetic particles 1. On the other hand, if the amount is too large, the Fe concentration will be diluted, which may result in a decrease in the saturation magnetic flux density and Curie temperature of the Fe-based soft magnetic particles 1.

[0036] Therefore, the amount of element M contained in the Fe-based soft magnetic particles 1 is preferably 1.0 mass % or more and 20 mass % or less. This makes it possible to easily form a good surface oxide phase 3, and maintain high saturation magnetic flux density and Curie temperature of the Fe-based soft magnetic particles 1. In other words, it is possible to obtain a magnetic wedge 100 with high electrical resistance, bending strength, and magnetic shielding properties.

[0037] Furthermore, the element M may be selected from a single element or two or more elements, such as Al and Cr, Si and Cr, etc. For example, two elements, Al and Cr, may be selected to form the Fe-based soft magnetic particles 1 as Fe-Al-Cr alloy particles. This allows for the formation of a favorable surface oxide phase 3, in which the total content of element M is higher than that of the interior of the Fe-based soft magnetic particles 1, even with a relatively small amount of Al. This means that the magnetic wedge 100 has high bending strength and an adjusted relative permeability. The Fe-Al-Cr alloy is an alloy in which the second most abundant element after Fe is Cr and Al (in any order), and other elements may be contained in smaller amounts than Fe, Cr, and Al. The composition of the Fe-Al-Cr alloy is not particularly limited, but the Al content is preferably 2.0% by mass or more, more preferably 5.0% by mass or more. From the viewpoint of obtaining a high saturation magnetic flux density, the Al content is preferably 10.0% by mass or less, more preferably 6.0% by mass or less. The Cr content is preferably 1.0 mass% or more, more preferably 2.5 mass% or more. From the viewpoint of obtaining a high saturation magnetic flux density, the Cr content is preferably 9.0 mass% or less, more preferably 4.5 mass% or less.

[0038] When two or more elements are selected as the element M, the total content thereof is preferably 1.0 mass % or more and 20 mass % or less, just like when one element is selected.

[0039] The Fe-based soft magnetic particles 1 may also be particles to which elements other than the element M have been added. However, it is preferable that these added elements are added in amounts smaller than the element M. Furthermore, the particles may be surface-treated by chemical means, heat treatment, or the like. The Fe-based soft magnetic particles 1 may also be composed of multiple types of Fe-based soft magnetic particles with different compositions.

[0040] Furthermore, the surface oxide phase 3 may contain Fe or other elements in addition to the element M, and the element concentrations of the elements M, Fe, etc. do not necessarily need to be uniform within the surface oxide phase 3. In other words, the element concentrations may differ at each grain boundary.

[0041] As explained above, the magnetic wedge 100 can have high electrical resistance and bending strength by having the Fe-based soft magnetic particles 1 and the surface oxide phase 3. Furthermore, this configuration and the gap 2 can provide the magnetic wedge 100 with high electrical resistance and bending strength and adjusted relative permeability.

[0042] Conventional magnetic wedges use iron powder dispersed in epoxy resin, with soft magnetic particles bonded together by the epoxy resin. This means that the resin softens and the bond strength may decrease in high-temperature environments. This means that problems with bending strength may arise when used at high temperatures, such as in rotating electrical machines. In contrast, the magnetic wedge 100 of this embodiment bonds particles together using the surface oxide phase 3 rather than resin. This prevents the bond strength between particles from decreasing at high temperatures, resulting in a magnetic wedge 100 with high bending strength even at high temperatures. For example, the reduction in three-point bending strength when heated from room temperature (25°C) to 150°C can be kept to less than 5%, more preferably less than 3%. Furthermore, the reduction in three-point bending strength when heated from room temperature (25°C) to 200°C can be kept to less than 10%, more preferably less than 5%.

[0043] Furthermore, as mentioned above, conventional magnetic wedges contain resin, which can decompose and deteriorate when exposed to high-temperature environments for extended periods, resulting in irreversible strength and dimensional reduction. In contrast, the resin-free magnetic wedge 100 of this embodiment does not encounter such problems. This also provides a magnetic wedge 100 with excellent heat resistance and long-term reliability. For example, the mass loss rate after 1,000 hours at 180°C can be less than 0.05%, more preferably less than 0.03%. Furthermore, the mass loss rate after 450 hours at 220°C can be less than 0.1%, more preferably less than 0.05%. Furthermore, the mass loss rate after 240 hours at 290°C can be less than 1%, more preferably less than 0.5%.

[0044] Furthermore, the heat resistance temperature of rotating electrical machines varies depending on the application and specifications, but some are set at 155°C or 180°C according to standards. In addition, some rotating electrical machines can reach temperatures as high as 200°C. The magnetic wedge 100 of this embodiment can maintain excellent bending strength even at high temperatures, and therefore can be suitably used in rotating electrical machines with maximum temperatures exceeding 180°C, and even 200°C, where magnetic wedges could not previously be installed.

[0045] Furthermore, the magnetic wedge 100 of this embodiment preferably uses the compact as a base and has an electrically insulating coating formed on its surface. This further increases the electrical resistance and strength of the magnetic wedge 100 and suppresses particle shedding from the compact surface, resulting in a highly reliable magnetic wedge 100. To suppress eddy current loss, an electrically insulating coating made of resin or oxide is preferred. For example, powder coating with epoxy resin, sealing coating by impregnation with varnish or silicone resin, or inorganic sealing coating by sol-gel method after impregnation with metal alkoxide can be used. Of these, inorganic sealing coating by sol-gel method is particularly preferred from the viewpoint of avoiding high-temperature deterioration of the resin.

[0046] (Second embodiment) Next, we will explain a magnetic wedge 200, which is a second embodiment of the present invention. Note that the magnetic wedge 200 of this embodiment differs from the magnetic wedge 100 of the first embodiment only in the particle configuration of the compacted body, and therefore will only be explained using enlarged schematic diagrams. Furthermore, since the same components as those of the first embodiment have the same effects, they will be assigned the same symbols and their explanations will be omitted.

[0047] FIG. 3 is an enlarged schematic diagram of a magnetic wedge 200. The magnetic wedge 200 is a compact of a plurality of Fe-based soft magnetic particles 1 containing element M, which is more easily oxidized than Fe, and a plurality of non-magnetic particles 4. The plurality of Fe-based soft magnetic particles are bound together by an oxide phase containing element M. In the example shown in FIG. 3, there are surface oxide phases 5 of the particles that bind the particles together, i.e., the surface oxide phases 5 of the Fe-based soft magnetic particles 1 or the non-magnetic particles 4, and voids 6 between the plurality of Fe-based soft magnetic particles 1 and the plurality of non-magnetic particles 4.

[0048] The non-magnetic particles 4 are particles that exhibit non-magnetic properties, and "non-magnetic" here means that they are not ferromagnetic at room temperature. Specifically, it refers to particles that exhibit paramagnetic, diamagnetic, or antiferromagnetic properties at room temperature. Furthermore, the non-magnetic particles 4 may be metal or non-metallic, such as an oxide.

[0049] The non-magnetic particles 4 are present between the Fe-based soft magnetic particles 1, thereby widening the average particle spacing of the Fe-based soft magnetic particles 1 and reducing the relative permeability of the magnetic wedge 200 due to the demagnetizing field effect. In other words, by adjusting the content of the non-magnetic particles 4, the magnetic wedge 200 can be made to have an adjusted relative permeability.

[0050] If the particle size of the non-magnetic particles 4 is large, it may hinder the bonding of the Fe-based soft magnetic particles 1 to each other or the relative magnetic permeability may become too low. On the other hand, if the particle size is small, it may be difficult to manufacture the particles themselves. Therefore, in a cross-sectional observation image of the magnetic wedge 200, the average maximum diameter of each particle of the non-magnetic particles 4 is preferably 0.5 μm or more and 15 μm or less, and more preferably 0.5 μm or more and 8 μm or less. Furthermore, the proportion of particles with a maximum diameter exceeding 40 μm is preferably less than 1.0%. In this way, it is possible to obtain a magnetic wedge 200 with an adjusted relative magnetic permeability while maintaining strength.

[0051] Furthermore, it is preferable that the average particle size of the non-magnetic particles 4 is smaller than the average particle size of the Fe-based soft magnetic particles 1. This allows the non-magnetic particles 4 to easily enter between the Fe-based soft magnetic particles 1, making the interparticle distances of the Fe-based soft magnetic particles 1 more uniform, and resulting in magnetic wedges 200 that exhibit stable magnetic properties.

[0052] Furthermore, the type of non-magnetic particles 4 is not particularly limited, but is preferably particles containing element M, which is contained in the Fe-based soft magnetic particles 1, i.e., element M that is more easily oxidized than Fe. For example, element M selected from Al, Si, Cr, Zr, and Hf can be included. By including such element M, a good surface oxide phase similar to that on the surface of the Fe-based soft magnetic particles 1 can be formed on the surface of the non-magnetic particles 4, and strong bonding can be achieved between the Fe-based soft magnetic particles 1 and the non-magnetic powder 2 particles, or between the particles of the non-magnetic powder 2, resulting in a magnetic wedge 200 with high bending strength.

[0053] The presence of the surface oxide phase 5 isolates the Fe-based soft magnetic particles 1 from one another, resulting in a magnetic wedge 200 with high electrical resistance. The surface oxide phase 5 is formed by bonding and integrating the surface oxide phase 3 of the Fe-based soft magnetic particles 1 with the surface oxide phase of the non-magnetic particles 4, resulting in a phase with different components between adjacent particles. However, by containing the same element M in both the Fe-based soft magnetic particles 1 and the non-magnetic particles 4, the surface oxide phase 5 can be made more homogeneous, primarily composed of element M. This allows the Fe-based soft magnetic particles 1 and the non-magnetic powder 2 to be firmly bonded together, resulting in a magnetic wedge 200 with high bending strength.

[0054] The non-magnetic particles 4 may be particles of element M alone, oxide particles containing element M, or alloy particles containing element M. When alloy particles are used, they are preferably Fe-based alloy particles with a higher concentration of element M than Fe-based soft magnetic particles, and the Curie temperature of the particles is preferably room temperature or lower, and more preferably -20°C or lower, and even more preferably -100°C or lower. The Fe-based alloy particles are preferably metal particles containing at least one of Al and Cr, and more preferably Fe-Al-Cr alloy particles are formed by selecting two elements M, Al and Cr, which allows for the formation of a good surface oxide phase 5 and results in a magnetic wedge 200 with high bending strength.

[0055] Like the magnetic wedge 100 of the first embodiment, the magnetic wedge 200 of this embodiment has high electrical resistance and bending strength and an adjusted relative magnetic permeability, but by including non-magnetic particles 4, the average particle spacing of the Fe-based soft magnetic powder 1 can be adjusted without increasing the gaps 2 between the particles. This makes it possible to obtain a magnetic wedge 200 with an adjusted relative magnetic permeability without compromising bending strength. Therefore, the magnetic wedge 200 of this embodiment is effective when the magnetic wedge 100 of the first embodiment cannot achieve the desired specifications in terms of strength, etc.

[0056] (Third embodiment) Next, a rotating electrical machine 300 according to a third embodiment of the present invention will be described. 4 is a schematic diagram of a rotating electric machine 300, showing a cross-sectional structure perpendicular to the rotation axis of the rotating electric machine 300. The rotating electric machine 300 is a radial gap type rotating electric machine, in which a stator 31 and a rotor 32 are arranged coaxially. The stator 31 has a plurality of teeth 34, around which coils 33 are wound, arranged at equal intervals in the circumferential direction.

[0057] In the rotating electric machine 300 of this embodiment, the magnetic wedge 100 of the first embodiment or the magnetic wedge 200 of the second embodiment is arranged at the rotor 32 side tip of the tooth 34 so as to connect the tip of the adjacent tooth 34.

[0058] The relative permeability and saturation magnetic flux density of the teeth 34 are typically designed to be higher than those of the magnetic wedges 100 or 200. This allows the magnetic flux from the rotor 32 that reaches the magnetic wedges 100 or 200 to flow into the teeth 34 via the magnetic wedges 100 or 200, suppressing the magnetic flux reaching the coils and reducing eddy current loss in the coils. Furthermore, when the rotating electric machine is running, most of the magnetic flux generated in the teeth 34 by the coil current flows into the rotor 32 across the gap, but some is attracted to the magnetic wedges and spreads circumferentially. This results in a smooth magnetic flux distribution in the gap between the stator 31 and the rotor 32. For example, in a rotating electric machine with a permanent magnet in the rotor 32, cogging can be suppressed and eddy current loss in the rotor 32 can be reduced. Furthermore, in an induction-type rotating electric machine with a squirrel-cage conductor in the rotor 32, secondary copper loss can be reduced. As described above, by disposing the magnetic wedge 100 or 200 according to the present invention in a rotating electric machine, it is possible to reduce losses and achieve a highly efficient and high-performance rotating electric machine 300.

[0059] The thickness of the magnetic wedge 100 or 200 (the radial dimension of the rotating electric machine) can be set appropriately taking into account the relative magnetic permeability, as mentioned above, but if it is too thin, the strength will decrease and its effectiveness as a magnetic wedge will also be weakened, so a thickness of 1 mm or more is preferable. On the other hand, if it is too thick, it will compress the space of the coil 33, contributing to increased copper loss, and the volume of the magnetic wedge 100 or 200 will increase, which will also increase the loss (iron loss) occurring in the magnetic wedge itself. Therefore, the thickness is preferably 5 mm or less, more preferably 3 mm or less, and even more preferably 2 mm or less. The width of the magnetic wedge 100 or 200 (the dimension in the circumferential direction of the rotating electrical machine) is set appropriately in accordance with the spacing between adjacent teeth 34, but is preferably in the range of 2 mm to 20 mm. The length of the magnetic wedge 100 or 200 (the dimension in the axial direction of the rotating electric machine) is also basically set appropriately according to the thickness (axial length) of the stator 31, but if it is too long, it will be difficult to manufacture and will be prone to breaking when attached to the rotating electric machine, making it difficult to work with. Therefore, the length is preferably 300 mm or less, more preferably 200 mm or less, and even more preferably 100 mm or less. On the other hand, if it is too short, the work of attaching it to the rotating electric machine will become complicated, which is undesirable. From this perspective, the length is preferably 25 mm or more, and more preferably 50 mm or more.

[0060] Furthermore, the cross-sectional shape of the magnetic wedge 100 or 200 is not limited to a rectangle and can be various other shapes. For example, as shown in FIG. 5, if the tip of the tooth 34 has a circumferential protrusion, the cross-sectional shape of the magnetic wedge 100 or 200 can be convex and arranged as shown. Furthermore, as shown in FIG. 6, the thickness of the magnetic wedge 100 or 200 can be varied in the width direction. In this case, it is preferable to use a cross-sectional shape that is relatively thin near the center in the width direction. This shape can suppress excessive short-circuiting of magnetic flux between the teeth with the thin-walled portion near the center, while effectively smoothing the spatial distribution of magnetic flux with the thick-walled portions at both ends, thereby achieving both high levels of torque and efficiency. Note that the thickness of the magnetic wedge 100 or 200 can vary in various ways, such as a curved or stepwise change, in addition to the linear change shown in FIG. 6.

[0061] (Fourth embodiment) Next, a method for manufacturing a magnetic wedge, which is a fourth embodiment of the present invention, will be described. 7 shows the process flow of this embodiment, which is the process flow for manufacturing the magnetic wedge 100 of the first embodiment. This process includes step S11 of mixing an Fe-based soft magnetic powder with a binder to form a mixture, step S12 of press-molding the mixture to form a green body, and step S13 of heat-treating the green body to form a consolidated body that will become the magnetic wedge 100.

[0062] First, in step S11, an Fe-based soft magnetic powder and a binder are mixed to form a mixture. The Fe-based soft magnetic powder used in step S11 is a powder that will become the Fe-based soft magnetic particles 1 in the magnetic wedge 100. It is a soft magnetic alloy powder mainly composed of Fe, and soft magnetic powder containing Co or Ni may also be used. In the following description, particles of the Fe-based soft magnetic powder may be referred to as the Fe-based soft magnetic particles 1.

[0063] The Fe-based soft magnetic powder preferably has an average particle size (median diameter d50 in the cumulative particle size distribution) of 1 μm to 100 μm, more preferably 5 μm to 30 μm. By using such an Fe-based soft magnetic powder, it is possible to manufacture a magnetic wedge 100 having Fe-based soft magnetic particles 1 with a preferred average particle size.

[0064] Furthermore, the Fe-based soft magnetic powder uses a powder containing element M, which is more easily oxidized than Fe, and the element M is preferably selected from Al, Si, Cr, Zr, and Hf. This makes it possible to easily form a good surface oxide phase 3 on the Fe-based soft magnetic particles 1 in step S13. Specifically, by oxidizing the compact of the Fe-based soft magnetic powder, it is possible to easily form a surface oxide phase 3 having a higher content of element M than the interior of the Fe-based soft magnetic particles 1.

[0065] The amount of element M contained in the Fe-based soft magnetic powder is preferably 1.0% by mass or more and 20% by mass or less, which makes it possible to easily manufacture a magnetic wedge 100 that has high electrical resistance, bending strength, and magnetic shielding properties.

[0066] Furthermore, the element M may be selected not only from one type but from two or more types. For example, two types, Al and Cr, may be selected to make the Fe-based soft magnetic powder into an Fe-Al-Cr alloy powder. In this way, it is possible to easily manufacture a magnetic wedge 100 with high bending strength and adjusted relative permeability. Note that an Fe-Al-Cr alloy is an alloy in which the elements with the second highest content after Fe are Cr and Al (in no particular order), and other elements may be contained in smaller amounts than Fe, Cr, and Al.

[0067] When two or more elements are selected as the element M, the total content thereof is preferably 1.0 mass % or more and 20 mass % or less, just like when one element is selected.

[0068] The Fe-based soft magnetic powder may contain an element other than the element M. However, it is preferable to add these additional elements in amounts smaller than the amount of element M. Furthermore, powder containing particles that have been surface-treated by a chemical method, heat treatment, or the like may be used.

[0069] In addition, the Fe-based soft magnetic powder can be produced by gas atomization or water atomization as a granular powder with good compactibility, or by pulverization as a flat powder for the purpose of utilizing shape anisotropy.

[0070] The binder is used in step S12 to temporarily bond the particles together and provide a certain degree of strength to the compact. The binder also serves to provide appropriate spacing between the particles. Examples of binders that can be used include organic binders such as polyvinyl alcohol and acrylic. It is preferable to add an amount of binder that is sufficiently dispersed throughout the mixture, ensures sufficient compact strength, and is sufficiently pyrolyzed in step S13. For example, it is preferable to add 0.5 to 3.0 parts by weight per 100 parts by weight of the Fe-based soft magnetic powder.

[0071] The mixing method in step S11 can be any known mixing method or mixer. The mixture of the Fe-based soft magnetic powder and the binder may become an agglomerated powder with a wide particle size distribution due to the adhesive action of the binder. In this case, the mixed powder may be sieved, for example, using a vibrating sieve, to obtain a granulated powder with the desired secondary particle size, before being used in step S12. Spray drying is preferably used to obtain a granulated powder with a spherical shape and uniform particle size. A lubricant such as stearic acid or a stearate salt may be added to the mixture to reduce friction between the powder and the mold in step S12. In this case, the amount added is preferably 0.1 to 2.0 parts by weight per 100 parts by weight of the mixed powder. The lubricant may not be added to the mixture in step S11, but may be applied to the mold in step S12.

[0072] Next, in step S12, the mixture obtained in step S11 is pressure-molded. For pressure molding, for example, a press and a molding die can be used. Pressure molding may be performed at room temperature, or may be performed as warm molding in which the mixture is heated to a degree that does not cause the binder to disappear.

[0073] Next, in step S13, the compact obtained in step S12 is heat treated to form a compact that will become a magnetic wedge.

[0074] In step S13, the compact is heat-treated to thermally decompose the binder present between the Fe soft magnetic particles 1 of the compact, forming voids between the particles, and by continuing the heat treatment further, voids 2 are formed between the Fe-based soft magnetic particles 1 and surface oxide phases 3 of the Fe-based soft magnetic particles 1 that bind the Fe-based soft magnetic particles 1 together.

[0075] The heat treatment can be performed in an atmosphere in which oxygen is present, such as in the air or in a mixed gas of oxygen and an inert gas, or in an atmosphere in which water vapor is present, such as in a mixed gas of water vapor and an inert gas.

[0076] The heat treatment is carried out at a temperature at which voids 2 can be formed between the Fe-based soft magnetic particles 1 and a surface oxide phase 3 of the Fe-based soft magnetic particles 1 that binds the Fe-based soft magnetic particles 1 together can be formed. However, if the heat treatment temperature is too low, the strain applied to the compact during molding may remain unrelieved, while if the heat treatment temperature is too high, the Fe-based soft magnetic particles 1 may sinter together, resulting in a magnetic wedge 100 with reduced electrical resistance and large eddy current loss. Therefore, the heat treatment temperature is preferably set in the range of 600°C to 900°C, and more preferably in the range of 700 to 800°C.

[0077] In this embodiment, the relative magnetic permeability of the magnetic wedge 100 can be adjusted by adjusting the molding load in step S12. For example, by reducing the molding load, the space factor of the Fe-based soft magnetic particles 1 in the compact, i.e., the space factor of the compacted body after step S13, can be reduced. As a result, the average particle spacing of the Fe-based soft magnetic particles 1 in the compacted body increases, and the relative magnetic permeability of the magnetic wedge 100 can be adjusted to be low. From this perspective, the molding pressure is preferably less than 1.0 GPa, and more preferably 0.7 GPa or less.

[0078] Furthermore, in this embodiment, the relative magnetic permeability of the magnetic wedge 100 can be adjusted by adjusting the heat treatment temperature in step S13. For example, by lowering the heat treatment temperature, the amount of surface oxide phase 3 formed between the Fe-based soft magnetic particles 1 in the compact is reduced, and the amount of voids 2 in the compact after step S13 is increased, thereby adjusting the relative magnetic permeability of the magnetic wedge 100.

[0079] In this embodiment, the particle size of the Fe-based soft magnetic alloy powder 1 in step S11 may be adjusted to adjust the relative permeability of the magnetic wedge 100. For example, by using soft magnetic alloy powder 1 with a smaller average particle size, the influence of the demagnetizing field generated in the Fe-based soft magnetic particles 1 of the compact can be strengthened, and the relative permeability of the magnetic wedge 100 can be adjusted to be lower.

[0080] (Fifth embodiment) Next, a method for manufacturing a magnetic wedge, which is a fifth embodiment of the present invention, will be described. 8 shows a process flow of this embodiment, which is a process flow for manufacturing the magnetic wedge 200 of the second embodiment. This process flow includes step S21 of mixing an Fe-based soft magnetic powder, a non-magnetic powder, and a binder to form a mixture, step S22 of press-molding the mixture to form a green body, and step S23 of heat-treating the green body to form a consolidated body that will become the magnetic wedge 200.

[0081] First, in step S21, an Fe-based soft magnetic powder, a non-magnetic powder, and a binder are mixed to form a mixture. The Fe-based soft magnetic powder used in step S21 is a powder that will become the Fe-based soft magnetic particles 1 in the magnetic wedge 200, and is the same as the Fe-based soft magnetic powder described in the fourth embodiment. In the following description, the Fe-based soft magnetic powder particles may be referred to as the Fe-based soft magnetic particles 1, and the non-magnetic powder particles may be referred to as the non-magnetic particles 4.

[0082] The non-magnetic powder preferably has an average particle size (median diameter d50 in the cumulative particle size distribution) of 1 μm to 80 μm, more preferably 3 μm to 20 μm. By using such non-magnetic powder, it is possible to manufacture a magnetic wedge 200 having non-magnetic particles 4 with a preferred average particle size.

[0083] It is also preferable to use a non-magnetic powder with an average particle size smaller than that of the Fe-based soft magnetic powder. By doing so, when the mixture is prepared, the non-magnetic particles 4 are easily dispersed between the Fe-based soft magnetic particles 1, making the interparticle distances of the Fe-based soft magnetic particles 1 more uniform, and facilitating the production of a magnetic wedge 200 that exhibits stable magnetic properties.

[0084] Furthermore, the non-magnetic powder used is a powder containing element M, which is contained in Fe-based soft magnetic powder, that is, element M that is more easily oxidized than Fe, and element M is preferably selected from Al, Si, Cr, Zr, and Hf, for example. In this way, a magnetic wedge 200 with high bending strength can be easily manufactured.

[0085] The non-magnetic powder may be a powder of element M alone, or an alloy powder containing element M. When using an alloy powder, it is preferable to use an Fe-based alloy powder with a high content of element M so that the Curie temperature is below room temperature. Furthermore, as the Fe-based alloy powder, for example, two elements M, Al and Cr, may be selected to use an Fe-Al-Cr alloy powder, which makes it possible to easily manufacture a magnetic wedge 200 with high bending strength.

[0086] The non-magnetic powder may also be a powder to which an element other than the element M has been added. Furthermore, powder containing particles that have been surface-treated by a chemical method, heat treatment, or the like may also be used.

[0087] As for the non-magnetic powder, powders produced by gas atomization or water atomization can be used as granular powders with good compactibility, and powders produced by pulverization can be used as flat powders for the purpose of utilizing shape anisotropy.

[0088] The binder used in step S21 can be an organic binder such as polyvinyl alcohol or acrylic, which is used in step S22 to temporarily bond the particles together at appropriate intervals and provide strength to the compact. It is preferable to add an amount of binder that is sufficient to be dispersed throughout the mixture, ensure sufficient compact strength, and be sufficiently pyrolyzed in step S23. For example, it is preferable to add 0.5 to 3.0 parts by weight per 100 parts by weight of the Fe-based soft magnetic powder and non-magnetic powder combined.

[0089] The mixing method in step S21 can be the same as that in step S11 of the fourth embodiment. The same applies to the amount of lubricant added.

[0090] Next, in step S22, the mixture obtained in step S21 is pressure-molded. For the pressure-molding, the same pressure-molding as in step S12 of the fourth embodiment can be used.

[0091] Next, in step S23, the compact obtained in step S22 is heat-treated to form a compact that will become the magnetic wedge. If metal non-magnetic particles 4 are used as the non-magnetic particles 4, there is a possibility that the non-magnetic particles 4 will undergo plastic deformation when the compact is formed, which may increase the strength of the magnetic wedge 200.

[0092] In step S23, the compact is heat-treated to thermally decompose the binder present between particles in the compact, forming voids 6 between the particles, and by continuing the heat treatment, a surface oxide phase 5 of the particles that binds these particles together is formed between the particles. Note that the heat treatment can be performed in the same manner as in step S13 of the fourth embodiment.

[0093] In this embodiment, the mixing ratio of the non-magnetic powder can be adjusted in step S21 to adjust the relative permeability of the magnetic wedge 200. For example, by increasing the mixing ratio of the non-magnetic powder, the average particle spacing of the Fe-based soft magnetic particles 1 in the compact after step S23 can be increased, and the relative permeability of the magnetic wedge 200 can be adjusted to be lower.

[0094] In this embodiment, the molding load in step S22 may be adjusted to adjust the relative permeability of the magnetic wedge 200. For example, by reducing the molding load, the amount of voids between the Fe-based soft magnetic particles 1 in the compact, i.e., the amount of voids in the compact after step S23, can be increased, and the average particle spacing of the Fe-based soft magnetic particles 1 in the compact after step S23 can be increased, thereby adjusting the relative permeability of the magnetic wedge 200 to a lower value.

[0095] In this embodiment, the heat treatment temperature in step S23 may be adjusted to adjust the relative permeability of the magnetic wedge 200. For example, by lowering the heat treatment temperature, the amount of surface oxide phase 3 formed between the Fe-based soft magnetic particles 1 in the compact is reduced, the amount of voids 6 in the compact after step S23 is increased, and the average particle spacing of the Fe-based soft magnetic particles 1 in the compact after step S23 is increased, thereby adjusting the relative permeability of the magnetic wedge 200 to a lower value.

[0096] In this embodiment, the particle size of the Fe-based soft magnetic alloy powder 1 in step S11 may be adjusted to adjust the relative permeability of the magnetic wedge 100. For example, by using soft magnetic alloy powder 1 with a small average particle size, the influence of the demagnetizing field generated in the Fe-based soft magnetic particles 1 of the compact can be strengthened, and the relative permeability of the magnetic wedge 100 can be adjusted to a lower value. [Example]

[0097] Below, an example of the first embodiment using an Fe-Al-Cr alloy as the Fe-based soft magnetic particles is shown. However, unless otherwise specified, the materials and compounding amounts described in this example are not intended to limit the scope of the present invention.

[0098] (Sample preparation method) An alloy powder of Fe-5%Al-4%Cr (mass%) was produced by high-pressure water atomization. The specific production conditions were as follows: pouring temperature 1650°C (melting point 1500°C), molten metal nozzle diameter 3 mm, pouring speed 10 kg / min, water pressure 90 MPa, and water volume 130 L / min. The raw materials were melted and poured in an Ar atmosphere. The average particle size (median diameter) of the produced powder was 12 μm, and the powder specific surface area was 0.4 m 2 / g, and the true density of the powder is 7.3 g / cm 3 The oxygen content of the powder was 0.3%. Polyvinyl alcohol (PVA) and ion-exchanged water were added to this raw powder to make a slurry, which was then spray-dried using a spray dryer to obtain a granulated powder. The amount of PVA added was 0.75 parts by weight per 100 parts by weight of raw powder. Zinc stearate was added to this granulated powder at a ratio of 0.4 parts by weight and mixed. This mixed powder was filled into a mold and press-molded at room temperature under a molding pressure of 0.9 GPa. The resulting compact was heat-treated in air at 750°C for 1 hour. The heating rate during this process was 250°C / h. The oxygen content of the compact after heat treatment was 2%.

[0099] The dimensions of the prepared sample are as follows: Sample for evaluating bending strength and heat loss: Width 2.0 mm x Length 25.5 mm x Thickness 1.0 mm. DC magnetization curve evaluation sample: 10mm square x 1.0mm thick. Sample for evaluating core loss and electrical resistance: outer diameter 13.4 mm x inner diameter 7.7 mm x thickness 2.0 mm (ring shape).

[0100] (Cross-sectional structure of the example) The cross-sections of the examples prepared as described above were observed using a scanning electron microscope (SEM / EDX), and the distribution of each constituent element was simultaneously investigated. The results are shown in Figure 9. Figure 9(a) is an SEM image, and Figures 9(b) to 9(e) are mapping images showing the distribution of Fe (iron), Al (aluminum), Cr (chromium), and O (oxygen), respectively. Brighter colors indicate greater amounts of the target element. Figure 9 shows that there is a large amount of aluminum and oxygen at the grain boundaries between the Fe-based soft magnetic particles, forming an oxide phase. Furthermore, it can be seen that the soft magnetic particles are bonded to each other via this oxide phase.

[0101] (Comparative Example) As a comparative example, a commercially available magnetic wedge material, a magnetic laminate plate, was used. This magnetic wedge was made by dispersing iron powder in a glass epoxy substrate, and was cut out to the required size for various measurements from a 3.2 mm thick plate.

[0102] (density / electrical resistivity) The density of the sample in the above example is 6.4 g / cm 3 The space factor (relative density), which is the value obtained by dividing the density of the sample by the true density of the powder, was 88%. On the other hand, the density of the comparative example was 3.7 g / cm 3 It was. The electrical resistivity measured using the ring-shaped sample in the example was 3×10 4 The electrical resistivity was calculated using the following formula: ρ (Ω m). Electrodes were formed by applying a conductive adhesive to two opposing flat surfaces of the ring sample, and the resistance value R (Ω) was measured when 50 V was applied using an Advantest R8340 digital ultra-high resistance meter. ρ(Ω·m)=R×A / t where A is the planar area of ​​the ring sample (m 2 ), t is the sample thickness (m). On the other hand, the electrical resistance of the comparative example was too low to be measured with the ultra-high electrical resistance meter, so it was measured using a resistance meter RM3545 manufactured by Hioki E.E. The sample used for measurement was a plate cut into 10 mm squares with electrodes formed on both sides. The probe of the resistance meter was pressed against the electrodes to measure the electrical resistance value in the plate thickness direction, and the electrical resistivity of the comparative example was calculated using the above formula, resulting in a value of 9 × 10 -3 The resistance was Ω·m.

[0103] (DC magnetization curve) The DC magnetization curve (BH curve) of the sample was measured using a DC magnetic fluxmeter (TRF-5AH manufactured by Toei Kogyo) by clamping the above 10 mm square sample between the magnetic poles of an electromagnet and applying a maximum magnetic field of 500 kA / m. The measurement results at room temperature are shown in Figure 10. The BH curve for the comparative example is also shown in the figure. The magnetic flux density value in an applied magnetic field of 160 kA / m was 1.60 T for the example and 0.76 T for the comparative example. Therefore, the relative permeability μ was 8.0 for the example and 3.8 for the comparative example. The relative permeability μi of the sample obtained from the AC magnetization curve (minor loop) measured at f=1 kHz and Bm=0.07 T was 59. The natural resonance frequency of the example was 150 MHz. An attempt was made to measure the core loss of the comparative example using the same method, but the permeability was too low to measure.

[0104] (Magnetic core loss) The ring specimens described above were wound with primary and secondary windings using polyurethane-coated copper wire. The number of windings was 50 turns on both the primary and secondary sides. The specimens were connected to a BH analyzer (IFG BH-550) equipped with a high-current bipolar power supply (NF Circuit Design Block BP4660) to measure iron loss Pcv. The measurement conditions were a frequency f of 50 Hz to 1 kHz and a maximum magnetic flux density Bm of 0.05 to 1.55 T. To prevent sample temperature rise due to Joule heat from the primary winding, the specimens were immersed in a cooling bath (Julabo High / Low Temperature Circulator FP50-HE) with a refrigerant temperature maintained at 23°C. Silicone oil (Shin-Etsu Chemical KF96-20cs) was used as the refrigerant. The measurement results are shown in Figure 11. The white circles in the figure represent measured values. As the figure shows, in the high Bm region, Pcv tends to gradually saturate as magnetic saturation is approached. In the motor characteristic simulation in the next section, this actual measured value was used as the iron loss for the example. Note that although actual measurements were only possible up to Bm = 1.55 T, it is possible that the magnetic wedge inside the motor could be magnetized up to about 2 T, which corresponds to the saturation magnetic flux density of the electromagnetic steel sheet. Therefore, for Pcv values ​​on the high Bm side exceeding 1.55 T, the measurement results were applied to the following equation using the least squares method, and the extrapolated value from this equation was used. Example: Pcv=6.9f / (1+(1.28 / Bm) 2 ) Here, the unit of Pcv is kW / m 3 The unit of Bm is T, and the unit of f is Hz. The solid line in Figure 11 is the calculated value of this formula. The iron loss of the comparative example was measured in the same manner as above. The sample used for measurement was ring-shaped, with an outer diameter of 20 mm, an inner diameter of 14 mm, and a thickness of 3.2 mm, and both the primary and secondary windings were wound with 85 turns. Because the comparative example had a lower magnetic permeability than the example, the maximum magnetic flux density Bm that could be measured was up to 0.6 T, but the measured value was approximately twice the Pcv of the example. In the motor characteristic simulation in the next section, this measured value was used as the iron loss of the comparative example. As with the example, the measurement results were applied to the following equation to determine the Pcv value when Bm > 0.6 T, and the extrapolated value from this equation was used. Comparison example: Pcv=6.7f / (1+(1.1 / Bm) 1.58 )

[0105] (Rotating electric machine characteristic simulation) The characteristics (efficiency and torque) when the magnetic wedge of the example or comparative example is installed in an induction-type rotating electric machine were calculated using an electromagnetic field simulation using the finite element method. In this calculation, the magnetization curve of Fig. 10 and the iron loss value described in the previous section were taken into account as the magnetic characteristics of the magnetic wedge 100. The specifications of the induction type rotating electric machine used in the electromagnetic field simulation are as follows: Stator: diameter 450mm x height 162mm Number of poles: 4 Number of slots: 36 Rotor and stator material: Electromagnetic steel sheet (50A1000) Rotating motor output: 150kW Rotation speed: 1425 rpm 12 shows the installation position of the magnetic wedge 100 used in this simulation. Calculations were performed with the magnetic wedge width (length in the circumferential direction of the rotating electric machine) set to 7.0 mm and the thickness (length in the radial direction of the rotating electric machine) set to 0.0 mm (no magnetic wedge), 1.5 mm, and 3.0 mm.

[0106] (Simulation results of rotating electrical machine characteristics) Figure 13 shows the results of an electromagnetic field simulation. This figure plots the calculation results, with the efficiency of the rotating electric machine on the horizontal axis and the torque of the rotating electric machine on the vertical axis. The torque on the vertical axis is a value normalized by the torque value when there is no magnetic wedge. When comparing the Example with a thickness of 3 mm with the Comparative Example, the Example achieved high efficiency, but the torque was lower than the Comparative Example. This is thought to be because the Example, which has a high relative permeability, experienced more magnetic flux short-circuiting between the teeth than the Comparative Example. Therefore, when the thickness of the Example was reduced to 1.5 mm in order to suppress magnetic flux short-circuiting, the same efficiency and torque as the Comparative Example were obtained.

[0107] As described above, efficiency can be improved while suppressing a decrease in torque by using an embodiment with high magnetic permeability for the magnetic wedge 100 and then adjusting the thickness of the magnetic wedge 100 to be thin. Furthermore, although not included in this electromagnetic field simulation, if the magnetic wedge 100 is made thinner, the space for the coil 33 increases accordingly, and the electrical resistance of the coil can be reduced by increasing the coil wire diameter, etc., and further improvements in efficiency can be expected.

[0108] (Temperature dependence of bending strength) Using the aforementioned rod-shaped samples, the three-point bending strength was measured from room temperature to 200°C using a universal testing machine (Instron Model 5969). The measurement conditions were: load cell capacity 500N, support diameter 4mm, indenter diameter 10mm, support distance 16mm, and test speed 0.5mm / min. The three-point bending strength σ was calculated from the load W (N) at break using the following formula. σ=3LW / (2bh2 ) Here, L is the distance between the supports, b is the width of the sample, and h is the thickness of the sample.

[0109] The three-point bending strength of the example obtained as described above is shown in Figure 14. The figure also shows the three-point bending strength of the comparative example. As shown in the figure, the three-point bending strength of the comparative example containing resin decreases significantly with increasing temperature, whereas the resin-free example of this embodiment does not decrease in strength even at a high temperature of 200°C, maintaining a high strength equivalent to that at room temperature.

[0110] (Heating loss) Because the internal temperature of a motor rises during operation, magnetic wedges must be durable enough to withstand prolonged exposure to high temperatures without experiencing degradation. To evaluate this durability, we measured the mass change (heat loss) due to aging using the aforementioned rod-shaped samples. Aging was performed in air at 220°C and 290°C. The samples were removed and cooled at regular intervals, and their mass was measured at room temperature. The heating temperatures were set at 220°C and 290°C for the following reasons: 220°C is the maximum temperature the motor's internal temperature can reach, and 290°C is used for accelerated heat loss testing. An electronic balance (AUW220D, manufactured by Shimadzu Corporation) with a minimum display of 0.01 mg was used to measure the mass. Because the rod-shaped samples used in this example were small, approximately 0.3 g, five samples were used to ensure measurement reliability.

[0111] The measurement results at 220°C are shown in Figure 15, and the measurement results at 290°C are shown in Figure 16. In both figures, the data for the Example is the average value of five samples. The figures also show the measurement results for the Comparative Example. At 220°C, the weight of the Comparative Example decreased by 0.56% after 456 hours, while the weight change for the Example remained less than 0.05%. At 290°C, the difference in weight change became more pronounced; after 240 hours, the weight loss for the Comparative Example was more than 10%, while the weight change for the Example remained less than 0.05%. Furthermore, when the three-point bending strength was measured after the above-mentioned 290°C aging, no change was observed in the bending strength of the Examples compared to before aging, whereas the strength of the Comparative Examples had decreased to the point that they broke when simply held in the hand. As described above, the present example has superior durability to long-term aging at high temperatures compared to the comparative example, and can be said to be a material with higher practicality as a magnetic wedge.

[0112] (thermal conductivity) The thermal diffusivities of the example and comparative example at room temperature were measured using a thermal diffusivity measuring device (LFA467 manufactured by Netzsch). 2 / s, the comparison example is 0.8 mm 2 / s. Furthermore, the specific heat at room temperature of the Example and Comparative Example was measured using a differential scanning calorimeter (Netzsch DSC404F1), and was 0.4 J / (g·K) for the Example and 0.5 J / (g·K) for the Comparative Example. Thermal conductivity was calculated by multiplying the thermal diffusivity, specific heat, and density. The result was 8.7 W / (m·K) for the Example and 1.5 W / (m·K) for the Comparative Example, indicating that the Example had a thermal conductivity approximately six times higher than that of the Comparative Example. Since the thermal conductivity of resin is generally low, less than one-tenth that of metal, the high thermal conductivity of the Example is thought to be due to its resin-free nature. By placing the Example, which has high thermal conductivity and excellent heat dissipation properties, as a magnetic wedge near the gap, which is the heat source, heat can be effectively dissipated, which is expected to improve the cooling efficiency of rotating electrical machines. The higher the thermal conductivity of the magnetic wedge, the better the cooling effect. For example, a thermal conductivity of 2.0 W / (m·K) or more is preferable, 5.0 W / (m·K) or more is more preferable, and 8.0 W / (m·K) or more is even more preferable. Furthermore, since the thermal conductivity of the electromagnetic steel sheets that make up the stators of rotating electrical machines is generally high at around 20 W / (m·K), the closer the thermal conductivity of the magnetic wedge is to this value, the greater the cooling effect can be expected. Therefore, the thermal conductivity of the magnetic wedge is preferably at least 1 / 10 of that of the magnetic material (electromagnetic steel sheets) that makes up the stator, more preferably at least 1 / 5, and even more preferably at least 1 / 3.

[0113] As described above, according to the present invention, the particles that make up the magnetic wedge are bound together by a surface oxide phase, making it possible to provide a magnetic wedge with high electrical resistance and bending strength. Furthermore, by adding voids to this structure, it is possible to provide a magnetic wedge with high electrical resistance and bending strength and an adjusted relative permeability. Furthermore, because the magnetic wedge of the present invention is constructed without resin, it can be a magnetic wedge with excellent heat resistance, heat dissipation, and long-term reliability.

[0114] Although the present invention has been described using the above-mentioned embodiment, the technical scope of the present invention is not limited to the above-mentioned embodiment and can be modified within the technical scope described in the claims. [Explanation of symbols]

[0115] 1:Fe-based soft magnetic particles 2:Void 3: Surface oxide phase 4: Non-magnetic particles 5: Surface oxide phase 6:Void 31: Stator 32: Rotor 33: Coil 34: Teeth 100, 200: Magnetic wedge 300: Rotating electric machine

Claims

1. A magnetic material having a plurality of Fe-based soft magnetic particles which are granular atomized powder, The magnetic wedge is resin-free, the plurality of Fe-based soft magnetic particles are bound together by an oxide phase, and the mass loss rate after 450 hours at 220°C is less than 0.1%.

2. 2. The magnetic wedge according to claim 1, wherein the mass loss rate after 240 hours at 290°C is less than 1%.

3. 3. The magnetic wedge according to claim 1, wherein the Fe-based soft magnetic particles are Fe-Al-Cr alloy particles.

4. 4. The magnetic wedge according to claim 1, wherein the rate of decrease in three-point bending strength when the temperature is increased from 25°C to 150°C is less than 5%.

5. A rotating electric machine using the magnetic wedge according to any one of claims 1 to 4.

Images