Magnetostrictive power generation device and magnetostrictive element for power generation

Abstract

To provide a magnetostrictive power generation device and a magnetostrictive element for power generation that are low cost yet have high power generation output.SOLUTION: A magnetostrictive power generation device includes a magnetostrictive element for power generation including a magnetostrictive portion formed of at least one grain-oriented electromagnetic steel sheet, a frame coupled to the magnetostrictive element for power generation, and a magnet, and the grain-oriented electromagnetic steel sheet is a grain-oriented electromagnetic steel sheet having a {110}<001> GOSS texture, and the magnetostrictive power generation device is configured such that a bias magnetic field is applied in a direction inclined by 5° to 35° with respect to the <001> orientation of the grain-oriented electromagnetic steel sheet. There is also provided a magnetostrictive element for power generation used in the device.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a magnetostrictive power generating device and a magnetostrictive element for power generation. [Background technology]

[0002] In the use of the Internet of Things (IoT), which has been developing in recent years, wireless sensor modules that integrate sensors, power sources, wireless communication devices, etc. are used to connect things to the Internet. There is a demand for the development of power generation devices that can generate electricity from energy generated in the environment where the device is installed, as a power source for such wireless sensor modules, without the need for regular manual maintenance such as battery replacement or charging.

[0003] One example of such a power generator is a magnetostrictive vibration power generator that uses inverse magnetostriction, which is the opposite effect of magnetostriction. Inverse magnetostriction is a phenomenon in which the magnetization of a magnetostrictive material changes when strain is applied to the material due to vibration or other causes. Magnetostrictive vibration power generators apply strain to the magnetostrictive material through vibration, and the change in magnetization caused by the inverse magnetostrictive effect generates an electromotive force in a coil wound around the magnetostrictive element according to the law of electromagnetic induction.

[0004] In the past, attempts have been made to increase the amount of magnetostriction in order to improve the power generation performance of magnetostrictive materials. This is because the larger the amount of magnetostriction, the larger the change in magnetic flux density (ΔB) due to inverse magnetostriction when tensile stress and compressive stress are alternately applied to the magnetostrictive material, and the larger the power generation output. One method for increasing the amount of magnetostriction in magnetostrictive materials is to control the crystal structure of the magnetostrictive material. The basic lattice structure of previously developed Fe-Co alloys and Fe-Ga alloys is the bcc structure, <100> Therefore, the Goss orientation {110} is used for rolling and recrystallization. <100> How to align the texture of single crystals <100> A method of cutting out the data along the direction is being implemented.

[0005] For example, regarding the magnetostrictive material Fe-Ga alloy, Patent Document 1 discloses a method for forming an Fe-Ga alloy sheet containing one or more additional elements selected from Al, Be, B, etc. In this forming method, a {110} Fe alloy having a large magnetostriction is formed by pack rolling. <001> In addition, Patent Document 2 discloses a magnetostrictive material in which carbide (Nb2C) is finely dispersed in an Fe-Ga alloy to refine the crystal structure and improve rolling workability. In Patent Documents 1 and 2, the magnetostrictive material is <001> It is used for direction.

[0006] Furthermore, Patent Document 3 discloses a magnetostrictive element for power generation that is a plate-shaped magnetostrictive element made of an Fe-Ga alloy or an Fe-Co alloy and has been subjected to a surface treatment, such as the formation of recesses (grooves) on the front and / or back surface of the element. In this invention, by forming recesses (grooves) on the front and / or back surface of the magnetostrictive element, the ratio of the total area of ​​magnetic domains containing 180° domain walls to the ratio of the total area of ​​magnetic domains containing 90° domain walls is controlled to fall within a specific range, thereby increasing the power generation output of the magnetostrictive power generation device. Patent Document 3 does not disclose the crystal orientation of the magnetostrictive material used.

[0007] Furthermore, examples of magnetostrictive materials other than Fe-Ga alloys and Fe-Co alloys include the Fe-Si alloys, i.e., electromagnetic steel sheets, disclosed in Patent Document 4. The electromagnetic steel sheets used in the invention of Patent Document 4 may be either oriented electromagnetic steel sheets or non-oriented electromagnetic steel sheets. When oriented electromagnetic steel sheets are used, the direction parallel to the magnetization direction of the 180° magnetic domain (i.e., <001> It is stated that when a compressive strain is applied while a bias magnetic field is applied in the direction of the magnetic flux density, the magnetic flux density changes significantly, and the amount of power generation increases. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] US Patent Application Publication No. 2008 / 0115864 [Patent Document 2] US Patent Application Publication No. 2015 / 0028724 [Patent Document 3] Japanese Patent Publication No. 2020-107715 [Patent Document 4] Patent Publication No. 2021-103921 Summary of the Invention [Problem to be solved by the invention]

[0009] As is clear from the descriptions in Patent Documents 1 to 4, various magnetostrictive materials are used in magnetostrictive power generating elements and magnetostrictive power generating devices. Patent Documents 1 to 3 describe FeGa alloys, which are known to have the largest magnetostriction, as magnetostrictive materials. However, FeGa alloys are manufactured by a single crystal pulling method (CZ method), and are therefore very expensive. Patent Document 3 describes an FeCo alloy, which is manufactured by a rolling method, but is also expensive because it contains Co. Such high raw material costs are one of the factors hindering the widespread use of magnetostrictive power generating devices.

[0010] The magnetic steel sheet used as the magnetostrictive material in Patent Document 4 is inexpensive compared to other magnetostrictive materials, but generates less power than magnetostrictive power generation devices that use FeGa alloys as magnetostrictive elements.

[0011] In view of these problems, there is a need for the development of a magnetostrictive power generation device that is low cost yet has a high power generation output. [Means for solving the problem]

[0012] In view of the above problems, a first aspect of the present invention is the following magnetostrictive power generation device. [1] A magnetostrictive power generation device comprising a magnetostrictive element for power generation including a magnetostrictive portion formed of at least one grain-oriented electromagnetic steel sheet, a frame coupled to the magnetostrictive element for power generation, and a magnet, wherein the grain-oriented electromagnetic steel sheet has a {110} <001> It is a grain-oriented electrical steel sheet with a GOSS texture, <001> A magnetostrictive power generation device configured so that a bias magnetic field is applied in a direction tilted by 5° to 35° relative to the azimuth. [2] Grain-oriented electrical steel <001> The magnetostrictive power generation device according to [1], wherein a bias magnetic field is applied in a direction tilted by 10° to 30° with respect to the azimuth. [3] A magnetostrictive power generation device as described in [1], wherein the magnetostrictive element for power generation further includes a stress control section formed of at least one sheet of elastic material, and is formed by a laminate in which a directional electromagnetic steel sheet and an elastic material are bonded together. [4] The magnetostrictive power generation device according to [3], wherein the laminate includes two grain-oriented electrical steel plates and one elastic material bonded therebetween. [5] The magnetostrictive power generation device according to [3], wherein the laminate is formed by joining grain-oriented electrical steel sheets and an elastic material via a brazing material portion.

[0013] A second aspect of the present invention is the following magnetostrictive element for power generation and a magnetostrictive power generation device including the same. [6] A magnetostrictive element for power generation including a magnetostrictive portion formed of at least one grain-oriented electromagnetic steel sheet, wherein the grain-oriented electromagnetic steel sheet has a {110} <001> It is a grain-oriented electrical steel sheet with a GOSS texture, <001> A magnetostrictive element for power generation configured so that a bias magnetic field is applied in a direction tilted by 5° to 35° with respect to the azimuth. [7] Grain-oriented electrical steel <001> The magnetostrictive element for power generation according to [6], configured so that a bias magnetic field is applied in a direction tilted by 10° to 30° with respect to the azimuth. [8] The magnetostrictive element for power generation according to [6], further comprising a stress control section formed of at least one sheet of elastic material, and configured as a laminate in which grain-oriented electrical steel sheets and an elastic material are bonded together. [9] The magnetostrictive element for power generation according to [8], wherein the laminate comprises two of the grain-oriented electrical steel sheets and one sheet of elastic material bonded between them.

[10] The magnetostrictive element for power generation according to [8], wherein the grain-oriented electromagnetic steel plate and the elastic material are joined via a brazing material portion.

[11] A magnetostrictive power generation device comprising the magnetostrictive element for power generation according to [6] above. [Effects of the Invention]

[0014] According to the present invention, the {110} <001> A magnetostrictive power generation device and a magnetostrictive element for power generation that are low cost yet have high power generation output are provided by using grain-oriented electrical steel sheets having a GOSS texture without undergoing processing such as surface treatment. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic diagram showing the structure of a magnetostrictive generating device of the present invention. [Figure 2] FIG. 2 is another schematic diagram showing the structure of the magnetostrictive generating device of the present invention. [Figure 3] The magnetostrictive portion of the grain-oriented electrical steel sheet measured in the example <001> 10 is a graph showing the relationship between the angle at which a bias magnetic field is applied relative to the azimuth and power generation performance. DETAILED DESCRIPTION OF THE INVENTION

[0016] 1. Magnetostrictive power generation device The first embodiment of the present invention is a magnetostrictive power generation device comprising a magnetostrictive element for power generation including a magnetostrictive portion formed of at least one grain-oriented electromagnetic steel sheet, a frame coupled to the magnetostrictive element for power generation, and a magnet, wherein the grain-oriented electromagnetic steel sheet has a {110} <001> It is a grain-oriented electrical steel sheet with a GOSS texture, <001> The present invention relates to a magnetostrictive power generating device configured so that a bias magnetic field is applied in a direction tilted by 5° to 35° with respect to the azimuth.

[0017] In the present invention, the "magnetostrictive power generating device" refers to a magnetostrictive power generating device comprising a magnetostrictive element for power generation including a magnetostrictive portion, a frame connected to the magnetostrictive element for power generation, and a magnet. In the magnetostrictive power generating device of the present invention, the magnetostrictive portion of the magnetostrictive element has a {110} <001> The magnetostrictive power generation device of the present invention is formed of a grain-oriented electrical steel sheet having a GOSS texture. Other configurations of the magnetostrictive power generation device of the present invention are not particularly limited and can be configured similarly to conventional magnetostrictive power generation devices. Specifically, in this device, a coil is mounted around the magnetostrictive element and a weight is attached to a frame. In such a device, magnetic field lines of a magnet pass through the magnetostrictive element and apply a bias magnetic field to the magnetostrictive portion. Vibration of the weight then vibrates the frame, applying tensile stress and compressive stress to the magnetostrictive element. At this time, the direction in which bending strain is applied to the magnetostrictive element and the direction in which a bias magnetic field is applied to the magnetostrictive element are parallel, and the magnetization of the magnetostrictive element is changed by the inverse magnetostriction effect, generating an induced current (or induced voltage) in the coil.

[0018] (1) Magnetostrictive element for power generation The magnetostrictive element in the magnetostrictive power generation device of the present invention refers to an element that includes a magnetostrictive part formed from a grain-oriented electromagnetic steel sheet and is capable of generating power based on the inverse magnetostriction of the magnetostrictive part (i.e., the generation of a magnetic field associated with a change in shape (distortion) of the magnetostrictive part). Structurally, it is a part that contributes to power generation, consisting of the magnetostrictive part or having a detection coil wound around an area that includes the magnetostrictive part. In an actual power generation device, the adjacent area outside the area around which the coil is wound also contributes to power generation, but in this specification, the area around which the coil is wound is defined as the magnetostrictive power generation element.

[0019] In the present invention, "electrical steel sheet" refers to a functional material, sometimes called "silicon steel sheet," in which silicon (Si) is added to iron (Fe) to improve the magnetic properties of iron. The electrical steel sheet in the present invention is an electrical steel sheet with a silicon content of 0.5% or more and 4% or less. Electrical steel sheets with a silicon content of 0.5% or more and 4% or less are suitable for use in magnetostrictive parts because the increase in electrical resistance due to the addition of silicon can suppress the generation of eddy currents that interfere with magnetization changes during AC vibration.

[0020] Grain-oriented electrical steel sheets are steel sheets in which the crystal orientation of the metal grains is aligned in the rolling direction. <001> Grain-oriented electrical steel sheets with a GOSS texture are those with a grain-oriented texture in the rolling direction. <001> The direction of the rolled surface is aligned with the {110} orientation. Grain-oriented electrical steel sheets have a lower saturation magnetostriction than FeGa alloys and FeCo alloys, but the present invention can generate power equivalent to or exceeding that of magnetostrictive power generation devices using conventional magnetostrictive materials.

[0021] In conventional magnetostrictive power generation devices, the magnetostriction amount of the magnetostrictive material is the highest <001> Generally, devices are constructed so that they are magnetized in the azimuth direction. However, the inventors' research has revealed that the Young's modulus of the magnetostrictive element also has a significant effect on the amount of power generated by magnetostrictive power generation devices, and they have focused on improving the amount of power generated by achieving an optimal balance between Young's modulus and saturation magnetic flux density. The inventors have used grain-oriented electrical steel sheets as magnetostrictive materials, and have <001> The voltage was measured when a bias magnetic field was applied from various directions tilted within the range of 0° to 90° relative to the orientation. <001> By configuring the device so that a bias magnetic field is applied in a direction tilted by 5° to 35°, preferably in a direction tilted by 10° to 30°, with respect to the azimuth, it is possible to achieve the following, as in the prior art: <001> magnetized in the azimuth direction (i.e. <001> It was found that the amount of power generated is improved compared to when a bias magnetic field is applied from a direction of 0° relative to the azimuth. The reason why the amount of power generated is improved when a bias magnetic field is applied within such a specific tilt range is not clear, but it is presumed as follows.

[0022] When generating electricity using a magnetostrictive power generation device, stress (e.g., bending strain) is applied to the magnetostrictive element and a bias magnetic field is applied, but the direction in which the bias magnetic field is applied to the magnetostrictive element is parallel to the direction in which stress is applied to the magnetostrictive element. When stress and a magnetic field are applied in a specific direction to the grain-oriented electrical steel sheet, it is thought that the magnetoelastic energy due to the inverse magnetostriction effect of the magnetic moment oriented in the

[0100] direction, which is the easy magnetization direction of the grain-oriented electrical steel sheet, and the elastic energy due to the Young's modulus, which indicates the mechanical properties, work together in a ratio that works well to generate voltage.

[0023] Specific examples of grain-oriented electrical steel sheets include Nippon Steel Corporation's Orient Core, Orient Core Hi-B (for example, 27ZH100), Orient Core Hi-B Laser, and Orient Core Hi-B Permanent.

[0024] There are no particular restrictions on the thickness of the grain-oriented electrical steel sheet that forms the magnetostrictive portion of the magnetostrictive element for power generation, but it is usually between 0.2 mm and 10 mm. If the thickness of the magnetostrictive portion is 0.2 mm or more, it is advantageous because it allows for a large change in magnetic flux and therefore a large generated voltage, while if it is 10 mm or less, it is advantageous because it makes it easier to design rigidity that is suitable for vibration.

[0025] The grain-oriented electrical steel sheet in the present invention may or may not be provided with an oxide-based coating. As will be described later, when grain-oriented electrical steel sheets are brazed, a stronger metal bond is formed between the grain-oriented electrical steel sheet and the brazing filler metal, so grain-oriented electrical steel sheets are preferably provided with an oxide-based coating. The oxide-based coating may be an insulating coating or a tension coating that is provided on commercially available grain-oriented electrical steel sheets for the purpose of reducing iron loss.

[0026] The number of grain-oriented electromagnetic steel sheets included in the magnetostrictive portion of the magnetostrictive element for power generation is not particularly limited and may be one or two or more sheets. However, the number of grain-oriented electromagnetic steel sheets is preferably one to 100, and more preferably two to 20. Because the generated voltage is proportional to the cross-sectional area of ​​the magnetostrictive element, it is possible to increase the generated voltage by stacking multiple grain-oriented electromagnetic steel sheets to increase the cross-sectional area. Furthermore, vibration generates AC magnetization in the grain-oriented electromagnetic steel sheet according to the vibration frequency. However, when AC magnetization occurs in the grain-oriented electromagnetic steel sheet, which is a magnetic material, eddy currents that interfere with the magnetization are generated. In this case, eddy currents are less likely to occur when the grain-oriented electromagnetic steel sheet is thin than when it is thick. Therefore, using a grain-oriented electromagnetic steel sheet with a thin thickness is advantageous in terms of power generation.

[0027] When the magnetostrictive portion includes multiple grain-oriented electromagnetic steel sheets, the magnetostrictive portion may include multiple sheets of the same grain-oriented electromagnetic steel sheet or several different types of grain-oriented electromagnetic steel sheets, but the grain-oriented electromagnetic steel sheets can be bonded to each other. There are no particular limitations on the method for joining the magnetostrictive electromagnetic steel sheets within the magnetostrictive portion. Examples include bonding with an adhesive or adhesive sheet, brazing, and liquid-phase diffusion bonding, with brazing joining being preferred. When multiple grain-oriented electromagnetic steel sheets are bonded to each other via brazing portions, when bending strain due to vibration is applied to the laminate during operation of the magnetostrictive power generation device, the joints made of the brazing material between the grain-oriented electromagnetic steel sheets can suppress the reduction of strain applied to the entire laminate. Furthermore, this suppression of strain reduction can suppress the reduction in the power generation output of the magnetostrictive power generation element.

[0028] Furthermore, when the magnetostrictive portion includes a plurality of grain-oriented electromagnetic steel sheets, the magnetostrictive power generation device of the present invention has a structure in which at least one of the grain-oriented electromagnetic steel sheets is <001> The device must be configured so that a bias magnetic field is applied in a direction tilted by 5° to 35° relative to the azimuth. Configuring the device in this way makes it possible to improve the amount of power generation. The remaining grain-oriented electrical steel sheets may or may not meet the above requirements regarding the bias magnetic field.

[0029] In magnetostrictive power generation devices, the magnetostrictive part of the magnetostrictive element for power generation is formed from grain-oriented electromagnetic steel sheets. <001> Whether or not a bias magnetic field is applied in a direction tilted by 5° to 35° with respect to the azimuth can be confirmed by the following method.

[0030] The magnetostrictive power generation device's magnetostrictive element is cut so that the plane formed by the longitudinal direction of the grain-oriented electrical steel sheet and the direction perpendicular to the sheet is exposed, and the cross section is exposed using the cross-section polisher method. The exposed cross section is measured using electron backscatter diffraction (EBSD). Information about the crystal orientation can be obtained by analyzing the obtained diffraction pattern. That is, in the grain-oriented electrical steel sheet sample, <001> You can see how the direction is oriented. For example, <001> The angle between the direction of the electron beam and the longitudinal direction of the grain-oriented electrical steel sheet sample can be determined. EBSD measurements are performed with an electron beam spot diameter of 0.5 μm and a step width of 0.10 μm.

[0031] The shape of the magnetostrictive element for power generation in the magnetostrictive power generation device of the present invention is not particularly limited, and varies depending on the configuration and dimensions of the magnetostrictive power generation device. For example, when a rectangular grain-oriented electromagnetic steel sheet is used as the magnetostrictive portion of the magnetostrictive element, the longitudinal axis of the grain-oriented electromagnetic steel sheet is <001> The grain-oriented electromagnetic steel sheet may be cut out so as to be inclined at an angle of 10° to 30° with respect to the azimuth direction. When a device is constructed using the grain-oriented electromagnetic steel sheet cut out in this way as the magnetostrictive portion of the magnetostrictive element, the direction in which a magnetic field is applied to the magnetostrictive element is determined by the angle of the grain-oriented electromagnetic steel sheet. <001> At the same time as the direction is tilted by 5° to 35° relative to the orientation, the direction in which the force is applied within the surface of the grain-oriented electromagnetic steel sheet that forms the magnetostrictive part is also <001> The direction can be tilted by 5° to 35° relative to the azimuth. Also, when the grain-oriented electromagnetic steel sheet used as the magnetostrictive portion of the magnetostrictive element has a square or circular shape, any one axis in the direction in which the bias magnetic field is applied can be regarded as the "longitudinal axis" when cutting out.

[0032] The larger the dimensions of the magnetostrictive element for power generation in the magnetostrictive power generation device of the present invention, the more the number of coil turns can be increased in the power generation device, and the greater the voltage that can be obtained. Therefore, there are no particular restrictions on the dimensions of the magnetostrictive element (the length of the region around which the coil is wound), but it is usually 5 mm or more and 150 mm or less, preferably 10 mm or more and 100 mm or less, and more preferably 20 mm or more and 70 mm or less.

[0033] The magnetostrictive element for power generation provided in the magnetostrictive power generation device of the present invention may further include at least one stress control section formed of an elastic material, and may be formed by a laminate in which grain-oriented electrical steel sheets and the elastic material are bonded together. The "stress control section" in the magnetostrictive element is a part for controlling stress in order to achieve either a compressive or tensile stress load on the entire magnetostrictive section when bending strain or the like is applied to the magnetostrictive element.

[0034] Using a nonmagnetic material for the elastic material that functions as the stress control section is preferable because the magnetic field flows preferentially only through the magnetostrictive portion of the magnetostrictive element, making it easier to adjust the bias magnetic field of the magnetostrictive portion. Furthermore, when a magnetostrictive portion is formed of a grain-oriented electromagnetic steel sheet and a stress control section is formed of a nonmagnetic material, a larger change in magnetic flux density occurs compared to other combinations when bending strain is applied to a magnetostrictive element. This is thought to be because, when a magnetic material is used as the elastic material, magnetic interaction occurs between the elastic material and the grain-oriented electromagnetic steel sheet, which can hinder the conversion between 90° and 180° magnetic domains. However, when the elastic material is a nonmagnetic material, such magnetic interaction does not occur, making it easier for the grain-oriented electromagnetic steel sheet to convert between 90° and 180° magnetic domains.

[0035] Examples of non-magnetic elastic materials include, but are not limited to, fiber-reinforced plastics (e.g., glass fiber-reinforced plastic (GFRP), carbon fiber-reinforced plastic (CFRP)), austenitic stainless steel (e.g., SUS304, SUS316, etc.), copper alloys (e.g., brass, phosphor bronze), aluminum alloys (e.g., duralumin), and titanium alloys (e.g., Ti-6Al-4V). Among these, fiber-reinforced plastics and austenitic stainless steel are preferred because they have a relatively high Young's modulus and it is easy to position the neutral plane outside the magnetostrictive portion when a bending strain is applied.

[0036] Using a magnetic material as the elastic material is effective in reducing costs. When the magnetostrictive portion of a magnetostrictive element is made of a grain-oriented electromagnetic steel sheet and the elastic material functioning as the stress control portion is made of a magnetic steel sheet, applying a bias magnetic field causes the bias magnetic field to flow through both the magnetostrictive portion and the stress control portion. However, the grain-oriented electromagnetic steel sheet that forms the magnetostrictive portion is a high-permeability material, and a large bias magnetic field flows through the magnetostrictive portion, which is thought to result in magnetic domain changes sufficient for power generation. However, compared to when the stress control portion is made of a non-magnetic material, the magnetic force applied to the magnetostrictive portion is reduced by the amount of magnetic flux flowing through the stress control portion made of a magnetic material. To compensate for this reduction in magnetic force, the strength of the magnets provided in the magnetostrictive power generation device can be increased.

[0037] Examples of elastic materials that are magnetic materials include, but are not limited to, general structural rolled steel (e.g., SS400), general structural carbon steel (e.g., S45C), high-tensile steel (e.g., HT80), ferritic stainless steel (e.g., SUS430), and martensitic stainless steel (e.g., SUS410).

[0038] The number of elastic materials contained in the elastic material layer is not particularly limited, and may be one or more. When multiple elastic materials are contained, they may include multiple sheets of the same elastic material or several different elastic materials, but the elastic materials are bonded to each other. There are no particular limitations on the method for bonding the elastic materials in the elastic material layer, but typical examples include lamination using an adhesive or adhesive sheet, brazing bonding, liquid phase diffusion bonding, etc.

[0039] There are no particular limitations on the dimensions of the elastic material that functions as a stress control section, but from the viewpoint of achieving either a compressive or tensile stress load on the entire grain-oriented electromagnetic steel sheet that forms the magnetostrictive section, it is desirable that it be the same as or larger than the grain-oriented electromagnetic steel sheet. There are also no particular limitations on the thickness of the elastic material that functions as a stress control section, but it is usually 0.02 mm to 50 mm, preferably 0.1 mm to 10 mm, and more preferably 0.2 mm to 5 mm. If the thickness of the elastic material is 0.02 mm or more, it is advantageous for achieving either a compressive or tensile stress load on the entire magnetostrictive section, and if it is 50 mm or less, interference with the vibration of the magnetostrictive element can be suppressed.

[0040] As described above, the laminate forming the magnetostrictive element for power generation has a magnetostrictive portion including at least one grain-oriented electromagnetic steel sheet, and optionally further has a stress control portion including at least one elastic material. There is no limit to the number of grain-oriented electromagnetic steel sheets and elastic materials, and examples include a laminate consisting only of grain-oriented electromagnetic steel sheets, a laminate having one grain-oriented electromagnetic steel sheet and one elastic material, a laminate having multiple grain-oriented electromagnetic steel sheets and one elastic material, and a laminate having multiple grain-oriented electromagnetic steel sheets and multiple elastic materials.

[0041] The laminate is preferably a laminate in which a non-magnetic material is laminated as an elastic material on a grain-oriented electrical steel sheet. <001> When a magnetostrictive power generation device is constructed for a laminate in which grain-oriented electromagnetic steel sheets, cut with their longitudinal direction tilted by 5° to 35° relative to the direction of the magnetostrictive element (orientation), are laminated with non-magnetic material, and compressive strain is applied to the grain-oriented electromagnetic steel sheet side and tensile strain is applied to the non-magnetic material side (i.e., the magnetostrictive element is bent toward the grain-oriented electromagnetic steel sheet side), a larger change in magnetic flux density occurs than when the magnetostrictive element is bent in the opposite direction.

[0042] A three-layer structure in which grain-oriented electromagnetic steel sheets are attached to both sides of a non-magnetic material is also preferred. In this structure, the neutral plane can be located within the non-magnetic material. When this three-layer structure is subjected to vibration strain due to bending, one of the grain-oriented electromagnetic steel sheets on both sides can always be in a compressive strain state, resulting in a large change in magnetic flux density efficiently. Furthermore, at this time, the compressive stress changes the crystalline magnetoanisotropy, resulting in an appropriate angle within the range of 5° to 35°. As the change in magnetic flux density increases, a larger induced voltage is generated in the detection coil.

[0043] The brazing filler metal portion present between grain-oriented electrical steel sheets and / or between grain-oriented electrical steel sheets and an elastic material is a joint formed by a metallic brazing filler metal that can be joined to the electrical steel sheets.

[0044] The brazing filler metal constituting the brazing filler metal portion is not particularly limited as long as it can form a metallic bond with the grain-oriented electrical steel sheet, and examples thereof include many types of brazing filler metals such as silver brazing filler metal, copper brazing filler metal, nickel brazing filler metal, iron brazing filler metal, gold brazing filler metal, aluminum brazing filler metal, titanium brazing filler metal, etc. Among various brazing filler metals, a brazing filler metal containing nickel (Ni) as a main element (hereinafter often abbreviated as "Ni-based brazing filler metal") is preferred in the present invention.

[0045] In the present invention, the brazing filler metal portion made of a Ni-based brazing filler metal preferably contains Ni as a primary element and at least one element selected from the group consisting of Cr, Si, Fe, B, P, C, Cu, and Mo. Brazing filler metals capable of forming such brazing filler metal portions include brazing filler metals having compositions such as BNi-1, BNi-1A, BNi-2, BNi-3, BNi-4, BNi-5, BNi-6, and BNi-7, as described in JIS Z 3265. Generally, joining grain-oriented electrical steel sheets using a brazing filler metal containing Ni as a primary element can form a strong bond. Although the reason for this is unclear, it has been observed that a strong metal bond is formed between the grain-oriented electrical steel sheet and the brazing filler metal, i.e., a region in which the Fe derived from the grain-oriented electrical steel sheet and the Ni derived from the brazing filler metal portion are alloyed.

[0046] The alloyed region can be confirmed by elemental analysis of a cross section in the thickness direction of the magnetostrictive element for power generation. There are no particular limitations on the method for elemental analysis of the cross section of the magnetostrictive element for power generation, but elemental analysis of the cross section can be performed using a scanning electron microscope (SEM) (sometimes abbreviated as "SEM-EDS") equipped with an energy dispersive X-ray analyzer (EDS), or line analysis using an electron probe microanalyzer (EPMA). In the present invention, the alloyed region is confirmed and measured by elemental analysis of the cross section of the magnetostrictive power generation element using SEM-EDS. An example of an SEM-EDS device is the JSM-7000F (EDS is JED-2300) manufactured by JEOL.

[0047] In addition, EDS point analysis is performed at multiple locations on the cross-section analysis line, and the concentrations of Fe and Ni can be determined by quantifying the composition of those locations. If there is variation in the measured values ​​on the same analysis line, the average value of the measured values ​​is used as the concentration.

[0048] Furthermore, in the region where the Fe derived from the grain-oriented electrical steel sheet and the Ni derived from the Ni-based brazing filler metal are alloyed, there is a region on the brazing filler metal side where the Fe concentration is higher than the Fe concentration in the brazing filler metal used. In this case, the increase in the Fe concentration on the brazing filler metal side is due to the diffusion of Fe from the grain-oriented electrical steel sheet to the brazing filler metal. The diffusion of 0.2 mass% or more of Fe into the brazing filler metal results in alloying of the diffused Fe and the Ni in the brazing filler metal, which is preferable. Therefore, the region where the Fe concentration is [Fe concentration in the brazing filler metal used] + 0.2 mass% or more is the region where the Fe derived from the grain-oriented electrical steel sheet and the Ni derived from the brazing filler metal are alloyed. It is more preferable that the amount of Fe diffusing from the grain-oriented electrical steel sheet to the brazing filler metal is 0.5 mass% or more. It is believed that the greater the diffusion amount, the larger the alloyed region and the stronger the joint.

[0049] Similarly, there is a region on the grain-oriented electrical steel sheet side where the Ni concentration is higher than the Ni concentration contained in the grain-oriented electrical steel sheet. The increase in the Ni concentration on the grain-oriented electrical steel sheet side is due to the diffusion of Ni from the brazing filler metal side to the grain-oriented electrical steel sheet. The diffusion of 0.2 mass% or more of Ni into the grain-oriented electrical steel sheet is preferable because it alloys the diffused Ni with the Fe of the electrical steel sheet. Therefore, on the grain-oriented electrical steel sheet side, the region where the Ni concentration is [the Ni concentration of the grain-oriented electrical steel sheet used] + 0.2 mass% or more is the region where the Fe derived from the grain-oriented electrical steel sheet and the Ni derived from the brazing filler metal are alloyed. It is more preferable that the amount of Ni diffusing from the brazing filler metal side to the grain-oriented electrical steel sheet is 0.5 mass% or more. It is thought that the greater the diffusion amount, the greater the alloyed region and the stronger the joint.

[0050] The width L of the alloyed region is preferably 2 μm or more. A width L of 2 μm or more is sufficient to achieve high joint strength. Since a larger width L increases joint strength, a width L of 4 μm or more is more preferable. The width L of the alloyed region can be determined by performing point analysis using EDS at multiple locations on the contact surface between the grain-oriented electrical steel sheet and the Ni-based brazing filler metal, quantifying the elemental composition, and determining the alloyed region (i.e., the region where the Fe concentration on the brazing filler metal side is [the Fe concentration contained in the brazing filler metal used] + 0.2 mass% or more, and the region where the Ni concentration on the grain-oriented electrical steel sheet side is [the Ni concentration of the grain-oriented electrical steel sheet used] + 0.2 mass% or more) based on the obtained Fe and Ni concentrations. Whether the width L of the alloyed region is 2 μm or more can also be confirmed by selecting any region of 2 μm or more from within the contact surface, including a region where the Fe concentration and Ni concentration are close to each other, based on the respective concentration profiles of Fe and Ni, and quantifying the elemental composition of the selected region.

[0051] Furthermore, when an alloyed region exists on both the grain-oriented electrical steel sheet side and the Ni-based brazing filler metal side, the alloyed region on the Ni-based brazing filler metal side and the alloyed region on the grain-oriented electrical steel sheet side are continuous, and a sum of the width L1 of the alloyed region on the Ni-based brazing filler metal side and the width L2 of the alloyed region on the grain-oriented electrical steel sheet side of 2 μm or more is sufficient to achieve high joint strength. Furthermore, widths L1 and L2 are preferably 1 μm or more, and more preferably 2 μm or more. This is because the larger widths L1 and L2 are, the higher the joint strength. Note that the brazing filler metal becomes liquid during brazing, so Fe from the grain-oriented electrical steel sheet easily diffuses into the liquid brazing filler metal, and therefore width L1 tends to be wider than width L2.

[0052] Brazing filler metals with Ni as the main element also have excellent corrosion resistance, which contributes to the durability of magnetostrictive power generation devices.

[0053] The brazing filler metal portion using a Ni-based brazing filler metal, which is a preferred brazing filler metal in the present invention, preferably further contains at least one oxide selected from the group consisting of Mg oxide, Cr oxide, and Si oxide. These oxides may originate from an oxide coating that was present on the surface of the grain-oriented electrical steel sheet and may be peeled off by the brazing filler metal and incorporated into the brazing filler metal. It is believed that the incorporation of oxides from the oxide coating of the grain-oriented electrical steel sheet into the brazing filler metal forms a strong metal bond between the grain-oriented electrical steel sheet and the brazing filler metal. While it is sufficient to contain any one of Mg oxide, Cr oxide, and Si oxide, two or three types may also be contained. These oxides are less likely to deform than metals. Therefore, a magnetostrictive element including a brazing filler metal portion containing these oxides is less likely to deform when subjected to bending strain due to vibration than a magnetostrictive element including a brazing filler metal portion that does not contain these oxides. As a result, the relaxation of strain between the layers of the laminate is further suppressed, improving power generation. The oxides in the brazing filler metal portion may exist alone or as a composite oxide containing at least one of these oxides.

[0054] Furthermore, the oxides in the brazing filler metal are preferably lumpy. The presence of lumpy oxides in the brazing filler metal makes deformation of the brazing filler metal less likely to occur. There are no particular limitations on the method for confirming the presence of lumpy oxides in the brazing filler metal. For example, the laminate can be cut perpendicular to the plate surface and the brazing filler metal in the cross section can be observed using a scanning electron microscope (SEM). The maximum diameter of the oxides present within the observed field of view can be measured and used as the size of the lumpy oxides. The size of the lumpy oxides is preferably 130 μm or less, more preferably 90 μm or less, and even more preferably 70 μm or less. A lumpy oxide size of 130 μm or less is preferable because it is difficult for the oxide to separate from the brazing filler metal matrix. Furthermore, the size of the oxide measured in the plate thickness direction of the laminate is preferably 95% or less, more preferably 70% or less, of the thickness of the brazing filler metal. A lumpy oxide size of 95% or less of the thickness of the brazing filler metal is preferable because it is difficult for the oxide to separate from the brazing filler metal matrix.

[0055] Furthermore, the brazing filler metal may contain Cu or Mo to improve the strength of the brazing filler metal itself.

[0056] Furthermore, when the magnetostrictive element has a plurality of brazing filler metal portions, the plurality of brazing filler metal portions may be formed from the same brazing filler metal, or brazing filler metal portions formed from different brazing filler metals may be mixed.

[0057] The thickness of the brazing filler metal is not particularly limited as long as it can join the grain-oriented electrical steel sheets, but is preferably 5 to 100 μm. If the thickness of the brazing filler metal is less than 5 μm, the metallurgical bond between the brazing filler metal and the grain-oriented electrical steel sheets may be insufficient. In particular, if the grain-oriented electrical steel sheets have an oxide coating on their surfaces, if the thickness of the brazing filler metal is less than 5 μm, the effect of peeling the oxide coating from the grain-oriented electrical steel sheet and incorporating it into the brazing filler metal will be reduced, resulting in insufficient metallurgical bond between the brazing filler metal and the grain-oriented electrical steel sheets and reduced joint strength. Note that even if the thickness of the brazing filler metal exceeds 100 μm, no further effects will be observed in terms of joint strength and durability.

[0058] Furthermore, the brazing filler metal portion may have voids of 50% or less in volume fraction. The voids have the effect of alleviating distortion, and if the volume fraction is 50% or less, durability is further improved. Even if the volume fraction of the voids is 0%, there are no problems with durability. Furthermore, the voids in the brazing filler metal portion alleviate distortion between the layers of the laminate, but if the volume fraction of the voids is 50% or less, the impact on power generation can be minimized. This is thought to be because more than 50% of the volume fraction between the layers is occupied by metallic brazing filler metal with high rigidity, which is firmly bonded to the grain-oriented electrical steel sheet.

[0059] (2) Frame The magnetostrictive generating device of the present invention further comprises a frame connected to the magnetostrictive element. In the present invention, the "frame" of the magnetostrictive generating device refers to the part that is joined to the magnetostrictive element, the weight, and the magnet, respectively, and that constitutes the main body of the magnetostrictive generating device. Furthermore, in the present invention, it is preferable that the frame is continuous with the magnetostrictive element, and that at least a part of the frame is made of the material that forms the magnetostrictive element. This means that at least the part of the frame adjacent to the magnetostrictive element (the part near the coil where the coil is not wound) is integral with the magnetostrictive element; it is not necessary that the entire frame be integral with the magnetostrictive element.

[0060] Hereinafter, a magnetostrictive power generating device will be described in which at least a part of the frame is made of a material that forms the magnetostrictive element.

[0061] In the frame of a magnetostrictive power generation device, there is a region made of the material that forms the magnetostrictive element (i.e., grain-oriented electromagnetic steel sheet, elastic material, or laminate thereof) extending from each end of the magnetostrictive element (so as to extend beyond the coil). The length of this region is at least 50% of the length of the coil, and preferably at least the length corresponding to the length of the coil. In such a magnetostrictive power generation device, the joint between the power-generating magnetostrictive element and the frame is not located within or near the magnetostrictive element, so stress concentration is less likely to occur at the joint when continuous bending strain is applied to the magnetostrictive element for power generation, improving the durability of the device. Furthermore, it is preferable that the material extending from the magnetostrictive element (i.e., grain-oriented electromagnetic steel sheet, elastic material, or laminate thereof) extend to the joint position of the weight that applies bending strain to the magnetostrictive portion, so that bending strain generated by the vibration of the weight is efficiently transmitted to the magnetostrictive element.

[0062] Furthermore, the portion of the frame made of the material that forms the magnetostrictive element preferably accounts for 20% or more of the overall length of the frame, and more preferably 40% or more. When the magnetostrictive element is formed from a laminate (i.e., a laminate of two or more grain-oriented electromagnetic steel sheets and / or a grain-oriented electromagnetic steel sheet and an elastic material), having 20% ​​or more of the overall length of the frame made of the laminate makes it possible to expand the joint surface between the two or more grain-oriented electromagnetic steel sheets included in the magnetostrictive element and / or between the grain-oriented electromagnetic steel sheet and the elastic material. As a result, the continuity within the components that make up the magnetic circuit is improved, reducing the occurrence of magnetic gaps, making it easier to adjust the bias magnetic field using magnets and stabilizing the voltage.

[0063] When only a portion of the frame is made of the material that forms the magnetostrictive element, there are no particular limitations on the material of the remaining portion of the frame; the frame can be completed by joining other steel plates, elastic materials, etc. However, from the standpoint of device durability and ease of manufacturing, it is preferable that the entire frame be integrally formed with the grain-oriented electromagnetic steel sheets that form the magnetostrictive element or grain-oriented electromagnetic steel sheets extending from the laminate. In particular, when the magnetostrictive element is formed of a laminate including grain-oriented electromagnetic steel sheet layers and elastic material layers, a structure in which grain-oriented electromagnetic steel sheets are present in the portion corresponding to the magnetostrictive element and the entire frame, and elastic material is laminated in the portion corresponding to the magnetostrictive element and the entire frame, or a structure in which elastic material is present in the portion corresponding to the magnetostrictive element and the entire frame, and grain-oriented electromagnetic steel sheets are laminated in the portion corresponding to the magnetostrictive element and the entire frame, is preferable. In such a structure in which the grain-oriented electromagnetic steel sheets or elastic material that constitutes the magnetostrictive element extends throughout the frame, both the magnetostrictive element and the frame can be manufactured by fabricating a laminate including grain-oriented electromagnetic steel sheets and elastic material. This simplifies the manufacturing process. Furthermore, it is particularly preferable that at least a portion of the directional electromagnetic steel plate and elastic material that constitute the magnetostrictive element extend to the fixing portion for fixing the magnetostrictive power generation device to a vibration source, etc., because this enables vibrations from the vibration source, etc. to be efficiently transmitted to the magnetostrictive element portion.

[0064] Furthermore, the entire frame may be made of the material that forms the magnetostrictive element (i.e., grain-oriented electromagnetic steel sheet, elastic material, or a laminate thereof). In particular, when the magnetostrictive element is formed of a laminate including grain-oriented electromagnetic steel sheet layers and elastic material layers, this configuration is preferable from the standpoint of durability, since the laminate including grain-oriented electromagnetic steel sheet and elastic material continuously forms both the magnetostrictive element and the frame, and there is no joint between the magnetostrictive element and the frame. Furthermore, since the continuity within the components that make up the magnetic circuit is increased, the occurrence of magnetic gaps is reduced, making it easier to adjust the bias magnetic field using magnets and further stabilizing the voltage.

[0065] Although there are no particular limitations on the dimensions of the frame containing the magnetostrictive element, the length of the frame containing the magnetostrictive element is generally 30 mm to 700 mm, preferably 60 mm to 500 mm, and more preferably 120 mm to 300 mm. The width of a typical frame is 4 mm to 70 mm, preferably 6 mm to 50 mm, and more preferably 8 mm to 30 mm. The frame dimensions can be reflected in the design according to the amount of power required to operate the device.

[0066] The shape of the frame is not particularly limited, and it can be plate-shaped or have a curved portion such as a U-shape, a V-shape, etc. In the present invention, since a highly tough grain-oriented electromagnetic steel sheet is used for the magnetostrictive element, not only plate-shaped frames but also U-shaped frames with curved portions can be manufactured from the magnetostrictive material that forms the magnetostrictive element.

[0067] The larger the dimensions of the magnetostrictive element for power generation in the magnetostrictive power generation device of the present invention, the more the number of coil turns can be increased in the power generation device, and the greater the voltage that can be obtained. Therefore, there are no particular restrictions on the dimensions of the magnetostrictive element (the length of the region around which the coil is wound), but it is usually 5 mm or more and 150 mm or less, preferably 10 mm or more and 100 mm or less, and more preferably 20 mm or more and 70 mm or less.

[0068] There are no particular limitations on the thickness of the grain-oriented electromagnetic steel sheet included in the magnetostrictive element and the grain-oriented electromagnetic steel sheet layer that forms the frame, but it is usually between 0.2 mm and 10 mm. If the thickness of the part corresponding to the magnetostrictive element is 0.2 mm or more, it is advantageous because it allows for a large change in magnetic flux and therefore a large generated voltage, while if it is 10 mm or less, it is advantageous because it makes it easier to design rigidity appropriate for vibration. The thickness of the grain-oriented electromagnetic steel sheet inside the magnetostrictive element and inside the frame may be the same or different.

[0069] There are no particular limitations on the thickness of the elastic material contained in the magnetostrictive element and the elastic material forming the frame, but it is usually 0.02 mm to 50 mm, preferably 0.1 mm to 10 mm, and more preferably 0.2 mm to 5 mm. If the thickness of the part corresponding to the magnetostrictive element is 0.02 mm or more, it is advantageous to achieve either a compressive or tensile stress load on the entire magnetostrictive part, and if it is 50 mm or less, it is possible to suppress interference with the vibration of the magnetostrictive element. The thickness of the elastic material within the magnetostrictive element and the frame may be the same or different.

[0070] (3) Magnets The magnetostrictive power generation device of the present invention further includes a magnet. There are no particular limitations on the size or number of magnets, and they can be selected according to the configuration of the device. It is preferable to use a permanent magnet to generate the bias magnetic field, because permanent magnets can be miniaturized and the bias magnetic field is easy to control. Furthermore, NdFeB magnets are preferred as permanent magnets because they can generate a larger bias magnetic field.

[0071] (4) Configuration of the magnetostrictive power generation device In the present invention, the magnetostrictive portion of the magnetostrictive element is formed of a grain-oriented electromagnetic steel sheet. <001> It is important to configure the magnetostrictive power generation device so that a bias magnetic field is applied in a direction tilted by 5° to 35° relative to the azimuth. As long as such a configuration is achieved, there are no particular limitations on the arrangement of the magnets and magnetostrictive elements. In the present invention, by using a magnetostrictive element manufactured as described below, it is possible to generate a magnetostrictive power generation device with the same configuration as a conventional magnetostrictive power generation device, using a grain-oriented electrical steel sheet. <001> It is possible to apply a bias magnetic field in a direction tilted by 5° to 35° relative to the azimuth.

[0072] A method for manufacturing a magnetostrictive element will now be briefly described. First, only the portion to be joined with the brazing material is prepared. The grain-oriented electromagnetic steel sheets (and elastic material) are sheared and cut to a predetermined size to prepare the number of grain-oriented electromagnetic steel sheets (and elastic material) to be used. At this time, for at least one of the grain-oriented electromagnetic steel sheets, the longitudinal axis of the cut shape (for example, strip shape) is aligned with the grain-oriented electromagnetic steel sheet. <001> The cutting is performed so that the angle is 10 to 30 degrees with respect to the azimuth. The angle set here will be the angle in the direction in which the bias magnetic field is applied in the final magnetostrictive power generation device.

[0073] Next, grain-oriented electromagnetic steel sheets (and elastic material) are stacked in the desired number and order with the brazing filler metal sandwiched between them. For example, the brazing filler metal may be in the form of a foil with a thickness of approximately 25 μm to 75 μm, or powdered brazing filler metal with a particle size of 150 μm or less. When using a foil-shaped brazing filler metal, it is also cut to the same size as the grain-oriented electromagnetic steel sheets (and elastic material) and laminated with the grain-oriented electromagnetic steel sheets (and elastic material). When powdered brazing filler metal is used, the powdered brazing filler metal is applied to the grain-oriented electromagnetic steel sheets and / or elastic material before lamination. A grain-oriented electromagnetic steel sheet layer containing two or more grain-oriented electromagnetic steel sheets can be produced by stacking the grain-oriented electromagnetic steel sheets, brazing filler metal, and elastic material in this order. It is also possible to produce a laminate containing a grain-oriented electromagnetic steel sheet layer and an elastic material layer by stacking the grain-oriented electromagnetic steel sheets, brazing filler metal, and elastic material in this order.

[0074] The stacked materials are subjected to heat treatment for brazing. While a single laminate may be subjected to heat treatment, multiple laminates can also be stacked together. For example, multiple stacks of magnetic steel sheets, brazing filler metal, and grain-oriented magnetic steel sheets can be stacked together in the following order: grain-oriented magnetic steel sheet / brazing filler metal / grain-oriented magnetic steel sheet / grain-oriented magnetic steel sheet / brazing filler metal / grain-oriented magnetic steel sheet / ...grain-oriented magnetic steel sheet / brazing filler metal / grain-oriented magnetic steel sheet; or multiple stacks of grain-oriented magnetic steel sheets, brazing filler metal, and elastic material can be stacked together in the following order: grain-oriented magnetic steel sheet / brazing filler metal / grain-oriented magnetic steel sheet / brazing filler metal / elastic material / ...grain-oriented magnetic steel sheet / brazing filler metal / grain-oriented magnetic steel sheet / brazing filler metal / elastic material. Because of the presence of an oxide film on the surface of grain-oriented magnetic steel sheets, the brazed laminates can be easily separated after brazing, even when grain-oriented magnetic steel sheets or grain-oriented magnetic steel sheets and magnetic materials are in contact with each other during heat treatment. However, to make separation easier, a release agent may be sprayed onto the surfaces of the grain-oriented electrical steel sheets before they are stacked.

[0075] Heat treatment for brazing is performed in an inert gas atmosphere such as Ar or in a vacuum, preferably using a furnace capable of heating in a vacuum. The brazing temperature varies depending on the brazing material used, but is preferably within 70°C of the melting point of the brazing material. Brazing temperatures exceeding 70°C of the melting point of the brazing material do not improve the strength or durability of the brazed portion. The heat treatment time is preferably approximately 5 to 120 minutes. When the number of layers in the laminate is large, the interior of the laminate may not reach the predetermined temperature even after the furnace temperature has risen to the predetermined temperature, so time is required for the temperature of the laminate to become uniform. Therefore, by maintaining the treatment temperature for a longer period, for example, 120 minutes, the interior of the laminate can be heated uniformly.

[0076] Furthermore, during the heat treatment for brazing, a load is applied to the laminate. There is no particular limitation on the load per unit area of ​​the laminate, but it is usually 0.1 g / mm 2 ~5g / mm 2 The load is preferably 0.1 g / mm 2If it is less than 5g / mm, the porosity in the brazing material will exceed 50%, which is not preferable as it may reduce the strength of the joint. 2 Even if a load of over 1000kJ is applied, no significant change occurs in the brazing material. To apply a load to the laminate, a hot press can be used, which can be used in a vacuum or in an inert gas atmosphere such as Ar.

[0077] A laminate in which all layers are bonded via brazing filler metal parts can be produced by the above method. When layers are bonded using a material other than brazing filler metal, the layer having the brazing filler metal part produced by the above method and another layer (for example, a plate of an elastic material or a laminate in which multiple layers are bonded with an adhesive) are bonded by a method other than brazing, for example, by using an adhesive.

[0078] Next, the basic configuration of the magnetostrictive power generating device of the present invention will be described with reference to Figs. 1 and 2, which are schematic diagrams of the device, but the device of the present invention is not limited to these.

[0079] 1 is a schematic diagram of a magnetostrictive power generation device 100 manufactured in accordance with the present invention, in which the magnetostrictive element and a portion of the U-shaped frame are formed of a laminate having a laminated structure of grain-oriented electromagnetic steel sheet / brazing material portion / elastic material / brazing material portion / grain-oriented electromagnetic steel sheet. The magnetostrictive element 110 included in the magnetostrictive power generation device 100 is formed of a laminate 120 having a laminated structure of grain-oriented electromagnetic steel sheet / brazing material portion / elastic material / brazing material portion / grain-oriented electromagnetic steel sheet, in which two grain-oriented electromagnetic steel sheet layers 121 and an elastic material layer 122 (grain-oriented electromagnetic steel sheet and non-magnetic material SUS304 in the present embodiment) are joined via a brazing material portion (not shown). In the magnetostrictive element 110, the grain-oriented electromagnetic steel sheet layer 121 serves as the magnetostrictive portion 111, the elastic material layer 122 serves as the stress control portion 112, and a detection coil 160 is mounted around the magnetostrictive element 110. The device 100 has a weight 140 for applying a strain to the magnetostrictive portion 111 and a magnet 150 for applying a bias magnetic field. Furthermore, the frame 130 of the device 100 is entirely composed of a laminate 120 extending from the magnetostrictive element 110, and can be fixed onto a vibration source or the like by a fixing portion 170.

[0080] 2 is a schematic diagram of a magnetostrictive power generation device 200 in which the magnetostrictive element and a portion of the U-shaped frame are formed of a laminate having a laminated structure of grain-oriented electromagnetic steel sheet / brazing material portion / elastic material / brazing material portion / grain-oriented electromagnetic steel sheet. The magnetostrictive element 210 included in the magnetostrictive power generation device 200 is formed of a laminated body 220 having a laminated structure of grain-oriented electromagnetic steel sheet / brazing material portion / elastic material / brazing material portion / grain-oriented electromagnetic steel sheet, in which two grain-oriented electromagnetic steel sheet layers 221 and an elastic material layer 222 (grain-oriented electromagnetic steel sheet and non-magnetic material SUS304 in this embodiment) are joined via a brazing material portion (not shown). In the magnetostrictive element 210, the grain-oriented electromagnetic steel sheet layer 221 serves as the magnetostrictive portion 211, the elastic material layer 222 serves as the stress control portion 212, and a detection coil 260 is mounted around the magnetostrictive element 210. The device 200 further includes a weight 240 for applying a strain to the magnetostrictive portion 211 and a magnet 250 for applying a bias magnetic field. Furthermore, the frame 230 of the device 200 is mostly composed of the laminate 220 extending from the magnetostrictive element 210, and the outer grain-oriented electromagnetic steel sheet layer 221 of the U-shaped frame 230 contacts the other grain-oriented electromagnetic steel sheet layer 221 disposed on the inside through a hole formed in the elastic material layer 222 at the fixing portion 270. Furthermore, the outer and inner grain-oriented electromagnetic steel sheet layers 221 of the U-shaped frame 230 are also in contact at the tip on the side where the weight 240 is disposed. By bringing the outer and inner grain-oriented electromagnetic steel sheets into contact in this manner, it becomes possible to efficiently magnetize the grain-oriented electromagnetic steel sheets using a magnet. Furthermore, the device 200 is provided with a support 280 at the U-shaped portion of the frame 230 to facilitate vibration of the magnetostrictive element 210 in the detection coil 260. The device 200 can be fixed to a vibration source or the like using the fixing portion 270, and a height adjustment plate 290 made of SUS304 stainless steel having the same thickness as the grain-oriented electromagnetic steel sheet is adhered to the fixing portion 270.

[0081] 2. Magnetostrictive elements for power generation The second embodiment of the present invention is a magnetostrictive element for power generation including a magnetostrictive portion formed of at least one grain-oriented electrical steel sheet, wherein the grain-oriented electrical steel sheet has a {110} <001> It is a grain-oriented electrical steel sheet with a GOSS texture, <001> The present invention relates to a magnetostrictive element for power generation that is configured so that a bias magnetic field is applied in a direction tilted by 5° to 35° with respect to the azimuth.

[0082] In the present invention, "grain-oriented electrical steel sheet" <001> The phrase "configured so that a bias magnetic field is applied in a direction inclined by 5° to 35° with respect to the azimuth" means that when the magnetostrictive element for power generation of the present invention is incorporated into any magnetostrictive power generation device, a magnetostrictive portion is formed, but the {110} <001> Grain-oriented electrical steel sheet with GOSS texture <001> This means that a bias magnetic field is applied in a direction tilted by 5° to 35° with respect to the azimuth. There are no particular limitations on the structure of a magnetostrictive power generation device that uses the magnetostrictive element for power generation of the present invention, and it may be configured in the same way as a conventional magnetostrictive power generation device.

[0083] The direction in which the bias magnetic field is applied to the magnetostrictive element can also be adjusted by adjusting the cutting direction of the grain-oriented electromagnetic steel sheet when manufacturing the magnetostrictive element. For example, when a magnetostrictive element has a rectangular magnetostrictive portion, and a magnet and a weight are placed at one end of the magnetostrictive power generation device, the longitudinal axis of the rectangular grain-oriented electromagnetic steel sheet is aligned with the direction of the grain-oriented electromagnetic steel sheet. <001> Grain-oriented electrical steel sheets are cut out so that they are inclined at 10° to 30° from the orientation. <001> The tilt with respect to the azimuth will be the tilt of the direction in which the bias magnetic field is applied in the final magnetostrictive power generation device. Also, when the grain-oriented electromagnetic steel sheet used as the magnetostrictive part of the magnetostrictive element is square or circular, any one axis in the direction in which the bias magnetic field is applied can be regarded as the "longitudinal axis" and cut out.

[0084] In addition, the magnetostrictive element for power generation is made of grain-oriented electromagnetic steel sheet that forms the magnetostrictive part. <001> Whether or not the bias magnetic field is applied in a direction tilted by 5° to 35° with respect to the azimuth can be confirmed by the following method.

[0085] The magnetostrictive element for power generation is cut so that the plane formed by the longitudinal direction of the grain-oriented electrical steel sheet contained therein and the direction perpendicular to the sheet is exposed, and the cross section is exposed using the cross-section polisher method. The exposed cross section is measured using electron backscatter diffraction (EBSD). Information about the crystal orientation can be obtained by analyzing the obtained diffraction pattern. That is, in the grain-oriented electrical steel sheet sample, <001> You can see how the direction is oriented. For example, <001> The angle that the direction makes with the longitudinal direction of the grain-oriented electrical steel sheet sample can be determined. Diffraction is performed with an electron beam spot diameter of 0.5 μm and a step width of 0.10 μm.

[0086] The materials and configuration of the magnetostrictive element for power generation of the present invention are all as explained above in relation to the magnetostrictive element for power generation provided in the magnetostrictive power generation device of the present invention.

[0087] The performance of a magnetostrictive element can be evaluated by assembling a magnetostrictive power generation device that includes the element and measuring its power generation performance. Even without fabricating a magnetostrictive power generation device, the magnetostrictive element can be fixed to a measurement unit that applies bending strain to the magnetostrictive element, and the change in magnetic flux density ΔB of the element that occurs when an external stress is applied to the magnetostrictive element can be used as an evaluation index. ΔB (unit: mT or T) can be calculated using the following method.

[0088] A magnetostrictive element with a cross-sectional area of ​​S is inserted into a coil with N turns and an external stress is applied. At this time, if a change in magnetic flux density ΔB occurs over time Δt, a voltage of V = -N(S ΔB / Δt) is generated in the coil. Therefore, ΔB can be calculated as the time integral of the voltage signal generated in the coil. The performance index of a magnetostrictive vibration power generator can be evaluated as the total voltage generated over Δt. In other words, it can be evaluated as the change in magnetic flux density ΔB, which is the time integral of the voltage. ΔB can be measured by connecting the voltage generated in the coil to a flux meter. The magnetic flux density change ΔB obtained by this measurement method is the time integral value of the voltage change, and therefore does not depend on the speed at which the strain is applied.

[0089] The present invention will be specifically explained below with reference to examples, but the present invention is not limited to these examples. [Example]

[0090] Magnetostrictive power generation device equipped with a magnetostrictive element consisting of grain-oriented electrical steel sheet / brazing material / SUS304 / brazing material / grain-oriented electrical steel sheet A magnetostrictive power generation device with the structure shown in Figure 1 was fabricated using grain-oriented electrical steel sheets as the electrical steel sheet layers and SUS304 as the elastic material layers. The electrical steel sheet layer was made of 35ZH110 grain-oriented electrical steel with a coating, manufactured by Nippon Steel Corporation. The thickness was 0.35 mm and the crystal orientation was {110} <001> The elastic material layer was made of a non-magnetic material, SUS304, and had a width of 150 mm and a length of 150 mm.

[0091] As shown in FIG. 1, the device fabricated here has an integrated structure including a magnetostrictive element 110 in which grain-oriented electromagnetic steel sheets are arranged on both sides of SUS304, and a frame 130. In the magnetostrictive element 110, the grain-oriented electromagnetic steel sheet layer 121 becomes the magnetostrictive portion 111, and the elastic material layer 122 (SUS304) becomes the stress control portion 112. At this time, the grain-oriented electromagnetic steel sheet <001> The grain-oriented electrical steel sheets were arranged so that their orientations were aligned. A 35 μm thick amorphous foil with a BNi-2 composition was used as the brazing filler metal, and the foil was cut to a length of 140 mm and a width of 140 mm. The brazing filler metal was sandwiched between each grain-oriented electrical steel sheet and the elastic material (SUS304) at the contact point, and the sheets were fixed in place to prevent misalignment. The brazing process was carried out in a vacuum at 1050°C for 10 minutes to form an integrated structure.

[0092] Then, the electromagnetic steel sheet on one side <001> The longitudinal direction was tilted at the angle shown in Table 1, based on the direction of shearing. A rectangle with a longitudinal length of 110 mm and a width of 8 mm was obtained. Next, using a hand bender, the rectangular plate was bent into a U-shape with a diameter of 12 mm to obtain an integrated structure with the shape shown in Figure 1. The length corresponding to the lower fixing part 170 was approximately 80 mm, and the length of the upper part where the detection coil 160 and weight 140 were attached was approximately 50 mm. After processing such as shearing, the grain-oriented electrical steel sheet was annealed in a vacuum at 800°C for 2 hours to remove distortion.

[0093] A 5000-turn detection coil 160 was mounted in the portion of the resulting integrated structure corresponding to the magnetostrictive element. The length of the coil was 15 mm. Next, a 7 g tungsten weight 140 was glued and fixed to the integrated structure. Furthermore, an NdFeB magnet was placed as a magnet 150 at the end in the longitudinal direction so that magnetic flux would be applied in the longitudinal direction. A magnetostrictive power generation device was obtained in which the entire frame was integrated with the magnetostrictive element.

[0094] The U-shaped lower fixing part 170 of the fabricated magnetostrictive power generation device was fixed on a vibrator with adhesive and vibrated at 0.5 G. Next, a bias magnetic field was applied using an NdFeB magnet, and the AC voltage induced in the detection coil of the magnetostrictive power generation device was captured with a digital oscilloscope and measured. At this time, the frequency was changed and the peak voltage at the resonant frequency was measured, and the performance of the magnetostrictive power generation device was evaluated based on the peak voltage of the measured voltage waveform. The magnet used was one whose peak voltage was maximized by varying the strength (size) of the magnet, and the strength of the magnetic field applied to the magnetostrictive element was estimated to be approximately 2800 A / m (350 e) for oriented electromagnetic steel sheets.

[0095] The results are shown in Table 1 and FIG. [Table 1]

[0096] As is clear from Table 1 and the graph in Figure 3, the <001> In the devices of Examples 1 to 5, which were configured so that a bias magnetic field was applied in a direction tilted by 5° to 35° relative to the azimuth, the peak voltage was 1.34 V or more. <001> In the devices of Examples 2 to 4 of the present invention, which are configured so that a bias magnetic field is applied in a direction tilted by 10° to 30° relative to the azimuth, the peak voltage is 1.41 V or more, and the grain-oriented electrical steel sheet <001> Compared to the device of Comparative Example 1 in which a bias magnetic field was applied in the azimuth direction (ie, the tilt was 0°), the peak voltage improved by a maximum of about 1.3 times. [Industrial Applicability]

[0097] The present invention provides a magnetostrictive material for power generation devices, which is less expensive than FeGa alloys and FeCo alloys, and which has a {110} <001> A magnetostrictive power generation device and a magnetostrictive element for power generation are provided that are low-cost and have high power generation output, using grain-oriented electrical steel sheet having a GOSS texture without undergoing processing such as surface treatment. The magnetostrictive element for power generation of the present invention is useful not only for wireless sensor modules in IoT and the like, but also as a power source for various devices. [Explanation of symbols]

[0098] 100, 200 Magnetostrictive power generation device 110, 210 Magnetostrictive elements for power generation 111, 212 Magnetostrictive part (magnetic steel sheet layer) 112, 212 Stress control section (elastic material layer) 120, 220 laminate 121, 221 grain-oriented electrical steel sheet layer 122, 222 Elastic material layer 130, 230 frames 140, 240 weight 150, 250 magnets 160, 260 detection coil 170, 270 Fixed part 280 Post 290 Height adjustment plate

Claims

1. a magnetostrictive element for power generation including a magnetostrictive portion formed of at least one grain-oriented electromagnetic steel plate; a frame coupled to the magnetostrictive element for power generation; Magnet and A magnetostrictive power generating device comprising: The magnetostrictive power generation device is configured such that the grain-oriented electrical steel sheet has a {110}<001> GOSS texture, and a bias magnetic field is applied in a direction inclined by 5° to 35° with respect to the <001> orientation of the grain-oriented electrical steel sheet.

2. 2. The magnetostrictive power generation device according to claim 1, wherein a bias magnetic field is applied in a direction tilted by 10° to 30° with respect to the <001> orientation of the grain-oriented electrical steel sheet.

3. 2. The magnetostrictive power generation device according to claim 1, wherein the magnetostrictive element for power generation further includes a stress control section formed of at least one sheet of elastic material, and is formed by a laminate in which the directional electromagnetic steel sheet and the elastic material are bonded together.

4. The magnetostrictive power generating device according to claim 3 , wherein the laminated body includes two of the grain-oriented electrical steel sheets and one sheet of the elastic material bonded therebetween.

5. The magnetostrictive power generating device according to claim 3 , wherein the laminate is formed by joining the grain-oriented electrical steel sheets and the elastic material via a brazing material portion.

6. A magnetostrictive element for power generation including a magnetostrictive portion formed of at least one grain-oriented electromagnetic steel plate, The magnetostrictive element for power generation is configured so that the grain-oriented electromagnetic steel sheet has a {110}<001> GOSS texture, and a bias magnetic field is applied in a direction inclined by 5° to 35° with respect to the <001> orientation of the grain-oriented electromagnetic steel sheet.

7. 7. The magnetostrictive element for power generation according to claim 6, wherein a bias magnetic field is applied in a direction inclined by 10° to 30° with respect to the <001> orientation of the grain-oriented electrical steel sheet.

8. 7. The magnetostrictive element for power generation according to claim 6, further comprising a stress control section formed of at least one sheet of elastic material, and configured as a laminate in which the grain-oriented electrical steel sheet and the elastic material are bonded together.

9. 9. The magnetostrictive element for power generation according to claim 8, wherein the laminate includes two of the grain-oriented electrical steel sheets and one sheet of the elastic material bonded therebetween.

10. 9. The magnetostrictive element for power generation according to claim 8, wherein the grain-oriented electrical steel sheet and the elastic material are joined via a brazing material portion.

11. A magnetostrictive power generation device comprising the magnetostrictive element for power generation according to claim 6.

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