阅读说明：本技术 磁致伸缩元件及使用其的磁致伸缩式振动发电装置 (Magnetostrictive element and magnetostrictive vibration power generation device using same ) 是由 中村太一 酒井一树 于 2019-07-25 设计创作，主要内容包括：本发明提供一种磁致伸缩元件及使用其的磁致伸缩式振动发电装置,磁致伸缩元件示出更大的发电量及发电密度。磁致伸缩元件由磁致伸缩材料构成,并且,在相互对置的第一端部及第二端部之间沿长边方向延伸,所述磁致伸缩材料是以下述式1表示的单晶合金,Fe<Sub>(100-α-β)</Sub>Ga<Sub>α</Sub>X<Sub>β</Sub>…式1,在式1中,α及β分别是以at％为单位的Ga含有率及以at％为单位的X含有率,X是从由Sm、Eu、Gd、Tb、Dy、Cu及C构成的组中选择的一种以上的元素,满足5≤α≤40且0≤β≤1,其中,该磁致伸缩元件与所述长边方向平行地具有所述单晶合金的＜100＞晶体取向,并且,Ga浓度具有在从所述第二端部朝向所述第一端部的方向上减少的梯度。(The invention provides a magnetostrictive element and a magnetostrictive vibration power generation device using the same, wherein the magnetostrictive element shows larger power generation amount and power generation density. The magnetostrictive element is made of a magnetostrictive material, and extends in the longitudinal direction between a first end and a second end which are opposite to each other, the magnetostrictive material being a single crystal alloy represented by the following formula 1, Fe (100‑α‑β) Ga α X β … formula 1, wherein in formula 1, α and β are the Ga content in at% and the X content in at%, X is at least one element selected from the group consisting of Sm, Eu, Gd, Tb, Dy, Cu and C, 5 ≤ α ≤ 40 and 0 ≤ β ≤ 1, respectively, and the magnetostrictive element has the single crystal alloy in parallel with the longitudinal direction<100> crystal orientation, and the Ga concentration has a gradient decreasing in a direction from the second end toward the first end.)

1. A magnetostrictive element which is made of a magnetostrictive material and extends in a longitudinal direction between a first end and a second end that are opposite to each other, the magnetostrictive material being a single crystal alloy represented by the following formula 1,

Fe_(100-α-β)Ga_αX_β… formula 1

In formula 1, α and β are the Ga content in at% and the X content in at%, respectively, X is at least one element selected from the group consisting of Sm, Eu, Gd, Tb, Dy, Cu and C, and satisfy 5. ltoreq. α. ltoreq.40 and 0. ltoreq. β. ltoreq.1,

the magnetostrictive element has a <100> crystal orientation of the single crystal alloy parallel to the longitudinal direction, and the Ga concentration has a gradient that decreases in a direction from the second end toward the first end.

2. The magnetostrictive element according to claim 1,

the magnetostrictive element has a plate-like shape.

3. The magnetostrictive element according to claim 1,

the Ga concentration is 14 at% or more and 16 at% or less at the first end portion, and is 17 at% or more and 19 at% or less at the second end portion.

4. The magnetostrictive element according to claim 1,

the Ga concentration decreases in a direction from the second end toward the first end at a ratio of 0.15 at% or more and 0.2 at% or less on average per 1 mm.

5. The magnetostrictive element according to claim 1,

x is one or more elements selected from the group consisting of Sm, Cu and C, and satisfies 14. ltoreq. α. ltoreq.19 and 0.5. ltoreq. β. ltoreq.1.

6. A magnetostrictive vibration power generator includes a power generating unit and a frame connected to the power generating unit,

the power generation unit has a first end and a second end, and includes: a vibration plate disposed at the first end of the power generation section and made of a nonmagnetic material; the magnetostrictive element according to claim 1 disposed at the second end of the power generating section; and a coil wound around the magnetostrictive element in the longitudinal direction,

the frame has a first end and a second end, and the second end of the power generation unit is connected to the first end of the frame, and the frame includes: a frame body extending between the first end and the second end of the frame and made of a magnetic material; and a magnet provided on the frame body so as to face the magnetostrictive element of the power generation section,

the magnetostrictive element is arranged such that a direction from the second end toward the first end of the power generation section corresponds to a longitudinal direction of the magnetostrictive element, and the vibrating plate is connected to the first end of the magnetostrictive element.

7. A magnetostrictive vibration power generation device according to claim 6,

the power generation unit and the frame have an コ -shaped configuration as a whole.

8. A magnetostrictive vibration power generation device according to claim 6,

the magnet is provided on the frame body so as to face the magnetostrictive element at the first end of the magnetostrictive element.

Technical Field

The present invention relates to a magnetostrictive element made of a magnetostrictive material and a magnetostrictive vibration power generation device using the magnetostrictive element.

Background

In recent years, the arrival of the world of the Internet of Things (IoT) in which objects having a function of autonomous communication exchange information with each other and automatically control each other has been expected. When IoT soaks into society, IoT devices with communication capabilities come on the market in large numbers. A power supply is required to operate an IoT device such as a sensor. However, when the number of devices becomes enormous, it becomes difficult to secure a power supply in terms of time and cost for wiring and maintenance. Therefore, when implementing IoT, a power supply technology suitable for IoT devices is desired. Based on such background, a technique of converting minute energy that is ubiquitous in our surroundings into electricity to be effectively utilized, that is, "energy harvesting" is considered important. Vibration, which is one of energy sources, is generated in a motor vehicle, a railway, a machine, a person, or the like, and thus, is generated in many places and is energy that is not influenced by weather or weather. Therefore, it is considered that the construction of a system for maintaining power supply of an application linked to the motion of these mobile bodies by vibration power generation can be the beginning of the realization of an IoT with higher efficiency.

The power generation methods by vibration power generation are classified into four types, i.e., a magnetostrictive type, a piezoelectric type, an electrostatic induction type, and an electromagnetic induction type. The magnetostrictive material is a system in which magnetic flux leaking to the outside along with a change in magnetic field inside the magnetostrictive material by applying stress is converted into electricity by a wound coil. Since the internal resistance is smaller than that of the other method, the power generation amount is large. Further, since a metal alloy is used as the magnetostrictive material, it has a characteristic of excellent durability. Therefore, the magnetostrictive type is expected as a mode capable of improving durability, which is one of the problems of the magnetostrictive type vibration power generation device or the element.

The magnetostrictive vibration power generator can be, for example, a device having a cantilever structure. A conventional magnetostrictive vibration power generation device having a cantilever structure includes: a magnetostrictive rod (or magnetostrictive element) composed of a magnetostrictive material; a coil wound around the magnetostrictive rod; a magnetic rod disposed in parallel with the magnetostrictive rod; a frame bent in an コ shape; and a magnet attached to the inside of the frame (see patent document 1). The frame is made of a magnetic material, and one end portion is a fixed end that is fixedly supported and the other end portion is a free end with the コ -shaped bent portion interposed therebetween. A part of the frame functions as a back yoke (back yoke), and a gap is formed between the magnet and an inner surface of the frame to which the magnet is not attached.

In the cantilever structure in which one end portion is a fixed end, when an external force (vibration) is applied in a horizontal plane, tensile and compressive stresses are applied to the magnetostrictive rod, and the magnetic lines of force change to an alternating magnetic field. Therefore, based on the electromagnetic induction law that voltage is generated in proportion to the time change of magnetic flux density, the coil is configured to generate voltage and output the voltage as electric energy.

Prior art documents

Patent document

Patent document 1: international publication No. 2015/141414

Disclosure of Invention

Problems to be solved by the invention

In the magnetostrictive vibration power generation device, the amount of power generation P is represented by P ═ NI · d/dt ([ integral ] BdA), and the power generation density E is represented by E ═ P/v. Here, N denotes the number of turns of the coil, I denotes the value of current flowing in the coil, B denotes the magnetic flux density of the magnetostrictive element, a denotes the cross-sectional area of the magnetostrictive element, and v denotes the volume of the magnetostrictive vibration power generation device. However, in the magnetostrictive vibration power generation device as described above, in the cantilever structure, when an external force (vibration) is applied in the horizontal plane, the stress applied to the magnetostrictive element by the fixed end is larger than the stress applied to the magnetostrictive element by the free end, and the stress is not uniformly applied to the magnetostrictive element, resulting in a stress distribution. Since the stress distribution is generated and the magnetic lines of force passing through the magnetostrictive element are also distributed, the change in the magnetic flux density B of the entire magnetostrictive element is small, and the power generation amount P is small. Therefore, the power generation density E (the amount of power generation P per unit volume) also decreases, and it is not possible to achieve high output of IoT (high power generation). For practical use, it is necessary to increase the power generation density E of the magnetostrictive vibration power generation device. For example, when a magnetostrictive vibration power generation device is applied to a tire air pressure monitoring system or a sensor network in a factory, the power consumption density is required to be about 1.0mW/cm³。

The invention aims to provide a magnetostrictive element and a magnetostrictive vibration power generation device which show larger power generation capacity and power generation density.

Means for solving the problems

According to a first aspect of the present invention, there is provided a magnetostrictive element that is formed of a magnetostrictive material and extends in a longitudinal direction between a first end and a second end that are opposed to each other, the magnetostrictive material being a single crystal alloy represented by the following formula (1),

Fe_(100-α-β)Ga_αX_β…(1)

in the formula (1), α and β represent the Ga content (at%) and the X content (at%), respectively, X represents one or more elements selected from the group consisting of Sm, Eu, Gd, Tb, Dy, Cu and C, and 5. ltoreq. α. ltoreq.40 and 0. ltoreq. β. ltoreq.1 are satisfied,

the magnetostrictive element has a <100> crystal orientation of the single crystal alloy parallel to the longitudinal direction, and the Ga concentration has a gradient that decreases in a direction from the second end toward the first end.

In one aspect of the first aspect of the present invention, the magnetostrictive element may have a plate-like shape.

In one aspect of the first aspect of the present invention, the Ga concentration may be 14 at% or more and 16 at% or less at the first end portion and 17 at% or more and 19 at% or less at the second end portion.

In one aspect of the first aspect of the present invention, the Ga concentration may decrease in a direction from the second end toward the first end at a ratio of 0.15 at% or more and 0.2 at% or less on average per 1 mm.

In one embodiment of the first aspect of the present invention, X is at least one element selected from the group consisting of Sm, Cu and C, and satisfies 14. ltoreq. α. ltoreq.19 and 0.5. ltoreq. β. ltoreq.1.

According to a second aspect of the present invention, there is provided a magnetostrictive vibration power generation device comprising a power generation unit and a frame connected to the power generation unit,

the power generation unit has a first end and a second end, and includes: a vibration plate disposed at the first end of the power generation section and made of a nonmagnetic material; the magnetostrictive element according to the first aspect disposed at the second end of the power generating section; and a coil wound around the magnetostrictive element in the longitudinal direction,

the frame has a first end and a second end, and the second end of the power generation unit is connected to the first end of the frame, and the frame includes: a frame body extending between the first end and the second end of the frame and made of a magnetic material; and a magnet provided on the frame body so as to face the magnetostrictive element of the power generation section,

the magnetostrictive element is arranged such that a direction from the second end toward the first end of the power generation section corresponds to a longitudinal direction of the magnetostrictive element, and the vibrating plate is connected to the first end of the magnetostrictive element.

In one aspect of the second aspect of the present invention, the power generating unit and the frame may have an コ -shaped configuration as a whole.

In one aspect of the second aspect of the present invention, the magnet may be provided on the frame body so as to be opposed to the magnetostrictive element at the first end of the magnetostrictive element.

Effects of the invention

According to the present invention, a magnetostrictive element and a magnetostrictive vibration power generation device that exhibit a larger amount of power generation and a larger power generation density are provided.

Drawings

Fig. 1 is a schematic view of a magnetostrictive element according to an embodiment of the present invention.

Fig. 2 is a graph showing a mode distribution of Ga concentration of the magnetostrictive element in the embodiment of the invention.

Fig. 3 is a cross-sectional view showing a magnetostrictive vibration power generation device provided with a magnetostrictive element in an embodiment of the present invention.

Fig. 4 is a perspective view showing a magnetostrictive vibration power generation device provided with a magnetostrictive element in an embodiment of the present invention.

Description of reference numerals:

1a magnetostrictive element;

1a first end of a magnetostrictive element;

1b a second end of the magnetostrictive element;

2a power generation section;

2a first end of the power generating section;

2b a second end of the power generating section;

3, a frame;

3a first end of the frame;

3b a second end of the frame;

3A a frame body;

4, a magnet;

5a vibrating plate;

6, a coil;

10 magnetostrictive vibration power generation device.

Detailed Description

Hereinafter, a magnetostrictive element, a method for manufacturing the same, and a magnetostrictive vibration power generation device provided with the magnetostrictive element according to embodiments of the present invention will be described. However, the present invention is not limited to the above embodiment.

< magnetostrictive element >

The magnetostrictive element in the present embodiment is made of a magnetostrictive material that is a single crystal alloy represented by the following formula (1) and extends in the longitudinal direction between a first end and a second end that face each other,

Fe_(100-α-β)Ga_αX_β…(1)

in the formula (1), α and β represent the Ga content (at%) and the X content (at%), respectively, X represents one or more elements selected from the group consisting of Sm, Eu, Gd, Tb, Dy, Cu and C, and 5. ltoreq. α. ltoreq.40 and 0. ltoreq. β. ltoreq.1 are satisfied,

wherein the magnetostrictive element has a <100> crystal orientation of the single crystal alloy parallel to the longitudinal direction, and the Ga concentration has a gradient that decreases in a direction from the second end toward the first end.

Note that the FeGaX single crystal alloy of formula (1) also includes a binary alloy of FeGa since β is 0.

In addition to the above formula (1), X is preferably one or more elements selected from the group consisting of Sm, Cu and C, and satisfies 14 ≦ α ≦ 19 and 0.5 ≦ β ≦ 1, and in other embodiments, in addition to the above formula (1), 14 ≦ α ≦ 19 and β ≦ 0 may be satisfied, and preferably 17 ≦ α ≦ 18.4 and β ≦ 0 may be satisfied.

The magnetostrictive element of this embodiment may have any suitable shape. For example, the shape may be a rectangular parallelepiped (also referred to as a plate shape), a cubic shape, a cylindrical shape, a polygonal prism shape, or another three-dimensional shape. Among them, a plate shape is preferable. In the case of a plate-like shape, the shape can be as follows: the size is, for example, about 5mm to 20mm in width and about 1mm to 3mm in height, preferably about 10mm in width and about 1mm in height, and the length in the longitudinal direction (the distance between one end and the other end facing each other) is about 10mm to 30mm, preferably about 30mm, and more preferably about 20 mm.

In the present disclosure, "Ga concentration" refers to a ratio of the number of atoms of the Ga element to the number of atoms of the entire alloy, and is a value expressed in units of at% (atomic percentage). More specifically, the content of Ga element is measured by analyzing the alloy with an electron beam microanalyzer (EPMA). The concentration or content of other elements (e.g., Fe, Sm, Eu, Gd, Tb, Dy, Cu, or C) contained in the alloy is also the value of at% (atomic%) measured by the same method. The single crystal alloy (FeGa alloy or FeGaX alloy) of the magnetostrictive material constituting the magnetostrictive element in the present embodiment may include a trace element (for example, oxygen at less than 0.005 at%) that is inevitably mixed, as long as the single crystal alloy is substantially composed of the listed elements.

In the present disclosure, the term "gradient" refers to a case where a predetermined value, such as concentration, changes in a decreasing or increasing manner in a direction from a specific site to another specific site. In the present disclosure, gradient means in particular changing in a monotonically decreasing or monotonically increasing manner. More specifically, in the present disclosure, the gradient of Ga concentration is measured by performing point analysis, line analysis, or the like at a plurality of positions from one end side to the other end side of the magnetostrictive element at the center of the magnetostrictive element by using EPMA.

In the present disclosure, the <100> crystal orientation of the single crystal alloy can be determined by a known method, but particularly refers to the <100> crystal orientation determined by an EBSD (Electron back scatter Diffraction) method. In the FeGa alloy or the FeGaX alloy, the <100> orientation is an orientation in which magnetization is easy, and therefore, the magnetostrictive element of the present embodiment can obtain a larger amount of magnetostriction by having the <100> crystal orientation of the single crystal alloy in parallel with the longitudinal direction thereof. Alternatively, even when the direction parallel to the longitudinal direction of the magnetostrictive element differs from the <100> crystal orientation of the FeGa alloy or the FeGaX alloy by as small an angle as possible of 10 ° or less, preferably 6 ° or less, and more preferably 4 ° or less, a large amount of magnetostriction can be obtained, and therefore, the magnetostrictive element can be used as the magnetostrictive element of the present embodiment.

The magnetostrictive element in the present embodiment will be specifically described with reference to the drawings.

Fig. 1 is a schematic view of a magnetostrictive element according to an embodiment of the present invention. The magnetostrictive element 1 is made of a magnetostrictive material that is a single crystal alloy represented by the above formula (1). As shown in fig. 1, the magnetostrictive element 1 extends in the longitudinal direction between a first end 1a of the magnetostrictive element, which is one end of the magnetostrictive element, and a second end 1b of the magnetostrictive element, which is the other end of the magnetostrictive element, which are opposite to each other, and has a plate-like shape. In the longitudinal direction between the first end 1a of the magnetostrictive element and the second end 1B of the magnetostrictive element, as shown in fig. 1, the second end 1B side of the magnetostrictive element is set to point a, the middle portion is set to point B, and the first end 1a side of the magnetostrictive element is set to point C. The magnetostrictive element 1 has the <100> crystal orientation of the single crystal alloy of formula (1) parallel to the longitudinal direction, and when the Ga concentration of the magnetostrictive element 1 is compared at the point a, the point B, and the point C, the values become higher in the order of the point a, the point B, and the point C.

Preferably, the Ga concentration is 14 at% or more and 16 at% or less at the first end 1a of the magnetostrictive element, and is 17 at% or more and 19 at% or less at the second end 1b of the magnetostrictive element. Preferably, the Ga concentration decreases in a direction from the second end 1b of the magnetostrictive element toward the first end 1a of the magnetostrictive element at a ratio of 0.15 at% or more and 0.2 at% or less on average per 1 mm. The Ga concentration at the first end 1a of the magnetostrictive element and the second end 1b of the magnetostrictive element may be a concentration at a position close to the edge (or side) of the magnetostrictive element 1, and for example, the Ga concentration in a region within a range of 0 to 3mm from the edge of the magnetostrictive element 1, typically a region of about 0.5 to 2.5 mm.

Fig. 2 is a graph showing a mode distribution of Ga concentration of the magnetostrictive element in the embodiment of the invention. The x-axis of fig. 2 shows the point a, the point B, and the point C of the magnetostrictive element 1. The y-axis shows the Ga concentration (at%) of the magnetostrictive element 1. For example, as shown in the graph of the mode distribution, the Ga concentration of the magnetostrictive element 1 in the present embodiment has a gradient of concentration from the point a toward the point C (in the longitudinal direction and in the direction from the second end 1b of the magnetostrictive element toward the first end 1a of the magnetostrictive element), and tends to decrease monotonously.

The magnetostrictive element 1 according to the embodiment of the invention has a gradient of Ga concentration, and therefore shows different magnetic characteristics (or magnetic anisotropy) in the gradient. More specifically, the magnetostrictive element 1 has different ratios of changes in magnetic flux density at different positions in the gradient of Ga concentration. In the present disclosure, the change in magnetic flux density when stress is applied can be measured by providing a B-H curve measuring device in a tensile compression tester.

The method for producing the magnetostrictive element 1 according to the present embodiment is not particularly limited, and any suitable alloy production method can be used. Examples thereof include the Czochralski (CZ) method, the Bridgman (Bridgeman) method, and the rapid solidification (rapid solidification) method. When the crystal is produced by the CZ method, the chemical composition and the crystal orientation can be produced with high accuracy in a large crystal. The gradient of Ga concentration can be formed in the magnetostrictive element 1 by measuring and confirming the gradient by EPMA analysis by rotating the crucible in the direction opposite to the rotation direction of the seed crystal and appropriately adjusting the conditions in each step (for example, the rotation speed, pressure, and the like of the seed crystal and the crucible) in the CZ method, for example, as long as those skilled in the art are concerned. Any known method can be used to obtain the magnetostrictive element 1 having a desired shape. For example, the cutting can be performed by wire electric discharge machining or the like.

< magnetostrictive vibration Power Generation device >

Fig. 3 is a cross-sectional view showing a magnetostrictive vibration power generation device provided with a magnetostrictive element in an embodiment of the present invention. Fig. 4 is a perspective view showing a magnetostrictive vibration power generation device provided with a magnetostrictive element in an embodiment of the present invention. As shown in fig. 3 and 4, the magnetostrictive vibration power generation device 10 includes a power generation unit 2 and a frame 3 connected to the power generation unit 2.

The power generating part 2 and the frame 3 have one and the other end portions, i.e., a first end portion 2a of the power generating part and a second end portion 2b of the power generating part, and a first end portion 3a of the frame and a second end portion 3b of the frame, respectively, and the second end portion 2b of the power generating part is connected to the first end portion 3a of the frame.

The method of connecting the second end 2b of the power generation section and the first end 3a of the frame is not particularly limited as long as the function of the magnetostrictive vibration power generation device 10 in the present embodiment, that is, the function of forming an appropriate magnetic circuit, is not significantly impaired as a whole. For example, a method of fixing with a screw, a bolt, a nut, a solder, an adhesive, a wax material, or the like is mentioned, and among them, a method of fixing with a screw, a bolt, or a nut is mentioned.

The frame 3 includes a frame body 3A and a magnet 4. The frame body 3A extends between the first end 3A of the frame and the second end 3b of the frame, and is made of a magnetic material, particularly a ferromagnetic material. Examples of the ferromagnetic metal material include cold-rolled steel sheets and steel strips (SPCC, SPCD, SPCE, SPCF, SPCG). The shape of the frame body 3A shown in fig. 3 and 4 is an コ -shaped shape, but is not particularly limited as long as it is a shape that ultimately connects the respective constituent elements to function as the magnetostrictive vibration power generation device 10. For example, the power generation unit 2 and the frame 3 connected to each other may have an コ -shaped or U-shaped configuration as a whole. More specifically, the power generation section 2 extending from the second end 2b of the power generation section to the first end 2a of the power generation section may be opposed to the frame body 3A extending in the direction toward the second end 3b of the frame, and the first end 2a of the power generation section (the end on the side of the vibration plate 5, that is, the end on the free end side) and the second end 3b of the frame (that is, the end on the fixed end side) may be in a shape facing each other.

The magnet 4 is provided on the frame body 3A so as to face the magnetostrictive element 1 of the power generation section 2. Preferably, the frame body 3A is provided so as to face the magnetostrictive element 1at the first end 1a thereof. Specifically, a gap may be formed between the magnet 4 and the magnetostrictive element 1. When the gap is formed in this manner, a magnetic closed circuit passing through the magnet 4, the magnetostrictive element 1, and the frame body 3A is appropriately formed via the gap. The magnet 4 is not particularly limited as long as it has a property of attracting a magnetic material and generates a bipolar magnetic field. Examples thereof include neodymium magnets, samarium-cobalt magnets, alnico magnets, and the like. Preferably, the magnet is a neodymium magnet.

As for the method of installing the frame body 3A and the magnet 4, for example, the magnet 4 may be placed only on the frame body 3A as a magnetic material. When the magnet 4 is placed, the magnetic force thereof can be applied in a state where the magnetic lines of force pass through the frame body 3A. Alternatively, the magnetic force may be set or connected by a method of passing another magnetic force. When the frame body 3A and the magnet 4 are bonded with an adhesive or the like through which magnetic lines of force hardly pass, a magnetic resistance is generated, and the size of the formed magnetic circuit is reduced.

As shown in fig. 3 and 4, the power generation unit 2 includes a diaphragm 5, the magnetostrictive element 1 in the above-described embodiment, and a coil 6.

The diaphragm 5 is disposed at the first end 2a of the power generation section. The material of the vibrating plate 5 is not particularly limited as long as it is made of a nonmagnetic material. For example, the material is made of a nonmagnetic metal (e.g., aluminum, titanium, copper, brass), a resin (e.g., acrylic resin), or the like. The resonance frequency can be adjusted by changing the spring characteristics of the diaphragm 5 by changing the dimensions (length and thickness) of the diaphragm 5 or by adding a weight to the diaphragm 5.

The magnetostrictive element 1 is disposed at the second end 2b of the power generation section. The magnetostrictive element 1 is the magnetostrictive element 1 in the above-described embodiment, but is arranged so that the direction from the second end 2b of the power generation section toward the first end 2a of the power generation section corresponds to the longitudinal direction of the magnetostrictive element 1, and is connected to the diaphragm 5at the first end 1a of the magnetostrictive element, that is, at the end side (near point C) where the Ga concentration is lower.

In the magnetostrictive element 1, the Ga concentration at the site a is higher, and therefore, when the applied stress is large, the difference in magnetic flux density between the no-load state and the stress state is large. On the other hand, since the Ga concentration at the site C is lower, the difference in magnetic flux density between the no-load state and the stress state becomes large when the applied stress is small. Therefore, in the magnetostrictive element 1, the second end 1b of the magnetostrictive element close to the point a is disposed on the frame side (fixed end side) and the first end 1a of the magnetostrictive element close to the point C is disposed on the diaphragm 5 side (free end side), so that the change in the magnetic flux density of the entire magnetostrictive element 1 made of the FeGa alloy or the FeGx alloy can be effectively increased. This is because, as the structure of the magnetostrictive vibration power generation device 10, there is a premise that the stress applied to the magnetostrictive element 1 by the fixed end is larger than the stress applied to the magnetostrictive element 1 by the free end. As a result, the power generation density of the magnetostrictive vibration power generation device 10 can be further increased. In the present disclosure, the difference in magnetic flux density between the no-load state and the stress state refers to the difference between the magnetic flux density measured by using the B-H curve measuring device in the no-load state and the magnetic flux density measured by placing the B-H curve measuring device in a tensile compression testing machine and applying tensile or compressive stress.

The method of attaching (or connecting) the diaphragm 5 and the magnetostrictive element 1 is not particularly limited. For example, the fixing method is performed by using a screw, a bolt, a nut, a solder, an adhesive, a wax material, a double-sided tape, or the like. Preferably, the fixing is performed by a screw, a bolt, a nut, or the like.

The coil 6 is wound around the magnetostrictive element 1 in the longitudinal direction in which the magnetostrictive element 1 extends, that is, in the direction from the second end 2b of the power generation section toward the first end 2a of the power generation section. The coil 6 generates a voltage in proportion to a temporal change of the magnetic lines of force passing in the magnetostrictive element 1 according to the law of electromagnetic induction. The material of the coil 6 is not particularly limited. For example, copper wire or the like can be used. The generated voltage can be determined from V · N · d Φ/dt. Here, N is the number of turns of the coil 6, and Φ is the magnetic flux. Therefore, the generated voltage can be increased by increasing the amount of change in the magnetic flux per unit time or increasing the number of turns of the coil 6. The amount of change in magnetic flux per unit time is determined by the mechanical characteristics of the power generating element, such as the resonant frequency thereof. Therefore, in order to increase the generated voltage of the power generating element, it is an easier method to increase the number of turns of the coil 6.