JP2021136734A - Power generator - Google Patents

Abstract

To provide a power generator capable of increasing a power generation amount by suppressing magnetic field distribution in a magnetostrictor.SOLUTION: A power generator comprises: a vibrating plate that extends in a first direction and includes a free end; a tabular magnetostrictor that extends in the first direction, is provided on one surface of the vibrating plate, and is made from magnetostrictive material; a coil provided around the magnetostrictor; a frame that has one end connected to the vibrating plate's one end on the opposite side to the free end and the other end connected to a vibration source and is made from non-magnetic material; a first magnet and a second magnet that apply magnetic fields to the magnetostrictor from directions along a plane crossing the first direction; and a magnetic plate which is disposed on the frame and on which the first magnet and the second magnet are mounted. The first magnet and the second magnet are disposed on the magnetic plate apart from each other along a second direction crossing the first direction so as to be substantially axially symmetric with respect to an axis of the coil. The first magnet's polarity on the magnetic plate side and the second magnet's polarity on the magnetic plate side are opposite to each other.SELECTED DRAWING: Figure 1A

Description

The present disclosure relates to a power generation device that uses a reverse magnetostrictive effect that converts mechanical energy applied to a reverse magnetostrictive element into electrical energy in power generation using vibration.

Vibration power generation includes a piezoelectric method, an electrostatic induction method, an electromagnetic induction method, a magnetostrictive method, and the like. The piezoelectric method using a piezoelectric element (piezo element) has a problem that mechanical durability is low due to the vulnerability of the piezoelectric element. In the electrostatic induction method, a MEMS (Micro Mechanical System) device using a Si (silicon) substrate is generally used, but since a semiconductor process is used, the cost tends to be high. Moreover, since it does not have ductility like metal, there is a problem in durability as in the piezoelectric method. The electromagnetic induction method has a problem that it is difficult to miniaturize because it has a moving part.
On the other hand, the magnetostrictive method using a metal-based magnetostrictive material is excellent in mechanical properties and workability because the magnetostrictive element is a ductile material. Further, since the magnetostrictive method has a low impedance electrically, it is highly adaptable to various circuits connected to a power generation device.

Magnetostrictive vibration power generation changes the magnetic field lines generated by the magnetostrictive effect by applying stress to the magnetostrictive element, and generates electromotive force in the coil wound around the magnetostrictive element according to the law of electromagnetic induction. It is a power generation method that changes mechanical energy into electrical energy.

For example, Patent Document 1 discloses a power generation device that performs magnetostrictive vibration power generation. Here, the power generation device of Patent Document 1 will be described with reference to FIGS. 9A and 9B. FIG. 9A is a schematic side view of the power generation device of Patent Document 1. FIG. 9B is a schematic cross-sectional view showing a cross-sectional structure seen in the direction AA in FIG. 9A.
As shown in FIGS. 9A and 9B, the power generation device 100 of Patent Document 1 includes a magnetostrictive element 101, a frame yoke 102, a magnetic portion 103, a back yoke 104, a magnet 105, a diaphragm 106, a weight 107, and a coil 108.

The magnetostrictive element 101 is attached to a frame yoke 102, which is a substantially U-shaped member made of a magnetic material. Further, the magnetic portion 103 formed in a part of the frame yoke 102 forms a parallel beam with the magnetostrictive element 101.
The back yoke 104 has a U-shape, and magnets 105 are attached to each end of the back yoke 104, and both magnets are sandwiched between the side surfaces of the frame yoke 102 with a gap. As such, the back yoke 104 is supported by the frame yoke 102.
Further, the diaphragm 106 is a part of the frame yoke 102 on the free end E1 side, and a weight 107 is attached to the tip of the diaphragm 106. The coil 108 is wound around a parallel beam portion composed of a magnetostrictive element 101 and a magnetic portion 103, and a current flows due to a change in magnetic flux generated by the magnetostrictive element 101. In such a power generation device 100, the fixed end E2 side of the frame yoke 102 is attached to the vibration source 109 via the metal fitting 110, and the vibration plate 106 and the weight 107 vibrate due to the transmission of vibration from the vibration source 109. An external force is applied to the magnetostrictive element 101 and the magnetic portion 103.

The magnetic portion 103 of the power generation device 100 is characterized in that it is magnetically saturated by a magnetic field from the magnet 105. A magnetic flux is generated by the magnetic field from the magnet 105, and the magnetic flux passes from the back yoke 104 through the magnetostrictive element 101 and the frame yoke 102 and returns to the magnet 105 again. (Arrows shown in FIGS. 9A and 9B) At this time, if the magnetostrictive element 101 is excited while the magnetic portion 103 is not magnetically saturated, the magnetic flux generated from the magnetostrictive element 101 flows to the magnetic portion 103, which is new. A recirculation path is formed, and the amount of power generation is reduced. By magnetically saturating the magnetic portion 103, it is possible to prevent the formation of a new reflux path and increase the amount of power generation.

Japanese Unexamined Patent Publication No. 2018-148791

However, the power generation device 100 of Patent Document 1 has the following problems.
The magnetostrictive element 101 has a rectangular plate shape, and the direction of the magnetic field generated from the magnet 105 is applied along the axis (X-axis) of the coil 108 substantially parallel to the side of the magnetostrictive element 101. In such a configuration, a large distribution is generated in the magnetic field in the magnetostrictive element 101 along the X-axis direction. That is, the magnetic field applied to the portion of the magnetostrictive element 101 closer to the magnet 105 is larger, and the magnetic field is smaller to the portion of the magnetostrictive element 101 farther from the magnet 105. The magnetic field inside the magnetostrictive element 101 has the same magnetic permeability when no load is applied, but the magnetic field at that time is inversely proportional to the square of the distance from the magnet, so that a magnetic field distribution is generated.

Here, the equation (1) representing the amount of power generated in the inverse magnetostrictive vibration power generation is shown.

In equation (1), P is the amount of power generated (W), V is the voltage (V), R is the electrical resistance (Ω), N is the number of coil turns (no unit), and S is the cross-sectional area of the magnetic strain material (m ² ). , F is the vibration frequency (Hz), σ is the coil resistance (Ω · m), L is the total coil winding length (m), r is the coil wire diameter (m), and ΔB is the change in magnetic flux density. Represents a quantity (T). When the structure is the same, it can be seen that the larger the ΔB, the larger the power generation amount P.

Further, FIG. 10 shows a schematic diagram of a BH curve showing the relationship between the magnetic flux densities generated when a magnetic field is applied to the magnetostrictive element. The horizontal axis is the magnetic field H (A / m), and the vertical axis is the magnetic flux density B (T). The magnetostrictive element behaves differently in the BH curve when it is pulled and when it is compressed. That is, as shown in FIG. 10, when a tensile force is applied, the change in the magnetic flux density B with respect to the magnetic field H is large, and when the magnetic field H exceeds a certain level, the magnetic flux density B is saturated. Further, when a compressive force is applied, the change in the magnetic flux density B with respect to the magnetic field H is small, but when the magnetic field H exceeds a certain level, it is saturated. In the configuration of Patent Document 1, when the power generation device 100 is vibrated, the free end E1 side has a cantilever structure having a large amplitude. In this case, the tensile and compressive stresses are alternately applied to the magnetostrictive element 101 due to the swing of the weight 107 at the tip. Further, since the magnetic field H applied by the magnet 105 is almost constant, it is possible to maximize the amount of power generation by generating the optimum magnetic field in which the difference between the magnetic flux densities B at the time of tension and the magnetic flux density B at the time of compression in the BH curve is the largest. Leads to.

However, as described above, in the configuration of Patent Document 1, since the magnetic field distribution is generated inside the magnetostrictive element 101, the magnetic flux density change ΔB also has a distribution, and the power generation amount P can be sufficiently increased. Have difficulty.

An object of one aspect of the present disclosure is to provide a power generation device capable of uniformly generating a change in magnetic flux density due to vibration and improving the amount of power generation.

The power generation device according to one aspect of the present disclosure includes a diaphragm extending in the first direction and having a free end.
A plate-shaped magnetostrictive element extending in the first direction and made of a magnetostrictive material provided on one surface of the diaphragm.
A coil provided around the magnetostrictive element and
A frame made of a non-magnetic material, one end of which is connected to one end of the diaphragm opposite to the free end and the other end of which is connected to a vibration source.
A first magnet and a second magnet that apply a magnetic field to the magnetostrictive element from a direction along a surface intersecting the first direction.
A magnetic plate arranged on the frame and mounting the first magnet and the second magnet,
With
The first magnet and the second magnet are separated from each other along a second direction intersecting with the first direction so as to be substantially line-symmetrical with respect to the axis of the coil. It is placed on a magnetic plate and
Further, the polarity of the first magnet on the magnetic plate side and the polarity of the second magnet on the magnetic plate side are opposite to each other.

According to the power generation device according to the present disclosure, the amount of power generation can be improved by reducing the magnetic field distribution in the magnetostrictive element and generating a uniform change in magnetic flux density.

It is a schematic side view of the power generation apparatus which concerns on Embodiment 1 of this disclosure. It is a schematic top view of the power generation apparatus which concerns on Embodiment 1 of this disclosure. It is a schematic diagram which shows the mode that the magnetic flux of the power generation apparatus which concerns on Embodiment 1 of this disclosure returns. It is a schematic perspective view of the power generation apparatus which concerns on Embodiment 1 of this disclosure. It is a graph which shows the magnetic field distribution along three lines of the magnetostrictive element in the power generation apparatus of FIG. 2A. It is a schematic side view of the power generation apparatus which concerns on the reference example with respect to Embodiment 1 of this disclosure. It is a schematic diagram which shows the mode that the magnetic flux of the power generation apparatus which concerns on a reference example with respect to Embodiment 1 of this disclosure recirculates. It is a schematic perspective view of the power generation apparatus which concerns on the reference example with respect to Embodiment 1 of this disclosure. It is a graph which shows the magnetic field distribution along three lines of the magnetostrictive element in the power generation apparatus of FIG. 4A. It is a schematic side view of the power generation apparatus which concerns on Embodiment 2 of this disclosure. It is a schematic top view of the power generation apparatus which concerns on Embodiment 2 of this disclosure. It is the schematic perspective view of the power generation apparatus which concerns on Embodiment 2 of this disclosure. 6 is a graph showing the magnetic field distribution along the three lines of the magnetostrictive element in the power generation device of FIG. 6A. It is a schematic side view of the power generation apparatus which concerns on Embodiment 3 of this disclosure. It is a schematic top view of the power generation apparatus which concerns on Embodiment 3 of this disclosure. It is the schematic perspective view of the power generation apparatus which concerns on Embodiment 3 of this disclosure. It is a graph which shows the magnetic field distribution along three lines of the magnetostrictive element in the power generation apparatus of FIG. 8A. It is a schematic side sectional view which shows the sectional structure of the power generation apparatus of Patent Document 1. FIG. 9 is a schematic cross-sectional view showing a cross-sectional structure in the AA direction in FIG. 9A. It is a graph which shows the BH curve when a stress is applied to a magnetostrictive element.

The power generation device according to the first aspect includes a diaphragm extending in the first direction and having a free end.
A plate-shaped magnetostrictive element extending in the first direction and made of a magnetostrictive material provided on one surface of the diaphragm.
A coil provided around the magnetostrictive element and
A frame made of a non-magnetic material, one end of which is connected to one end of the diaphragm opposite to the free end and the other end of which is connected to a vibration source.
A first magnet and a second magnet that apply a magnetic field to the magnetostrictive element from a direction along a surface intersecting the first direction.
A magnetic plate arranged on the frame and mounting the first magnet and the second magnet,
With
The first magnet and the second magnet are separated from each other along a second direction intersecting with the first direction so as to be substantially line-symmetrical with respect to the axis of the coil. It is placed on a magnetic plate and
Further, the polarity of the first magnet on the magnetic plate side and the polarity of the second magnet on the magnetic plate side are opposite to each other.

In the first aspect of the power generation device according to the second aspect, the first magnet or the second magnet is a group of magnets divided into two or more along the first direction. May be good.

In the power generation device according to the third aspect, in the second aspect, the magnet groups may be arranged at equal intervals.

In the power generation device according to the fourth aspect, in any one of the first to third aspects, the spatial distance between the first magnet and the second magnet is the same as that of the first magnet and the magnetostrictive element. Longer than the spatial distance of, and longer than the spatial distance between the second magnet and the magnetostrictive element.
The first magnet and the second magnet do not have to overlap the magnetostrictive element when viewed from the first direction and the third direction orthogonal to the second direction.

In the power generation device according to the fifth aspect, in any one of the first to fourth aspects, the coil is wound around the magnetostrictive element and the diaphragm with the first direction as an axis. You may.

The power generation device according to the sixth aspect may further include a weight arranged at the free end of the diaphragm in any one of the first to fifth aspects.

Hereinafter, each embodiment of the present disclosure will be described with reference to the accompanying drawings. The components common to each figure are designated by the same reference numerals, and the description thereof will be omitted as appropriate.

(Embodiment 1)
The power generation device 1 according to the first embodiment of the present disclosure will be described.

<Structure>
First, the configuration of the power generation device 1 according to the present embodiment will be described with reference to FIGS. 1A and 1B. FIG. 1A is a schematic side view of the power generation device 1 according to the first embodiment. FIG. 1B is a schematic top view of the power generation device according to the first embodiment of the present disclosure. For convenience, the longitudinal direction of the diaphragm 3 is shown as the X direction, the width direction is shown as the Y direction, and the vertically upper direction is shown as the Z direction.
As shown in FIGS. 1A and 1B, the power generation device 1 includes a magnetostrictive element 2, a diaphragm 3, a weight 4, a coil 5, a frame 6, a first magnet 7, a second magnet 8, and a magnetic plate 9.
The magnetostrictive element 2 is arranged so as to be laminated on the diaphragm 3, and a weight 4 is further arranged at the tip 3a which is a free end of the diaphragm 3. Further, a coil 5 for winding the magnetostrictive element 2 and the diaphragm 3 is provided around the laminated portion of the magnetostrictive element 2 and the diaphragm 3.

The frame 6 is a member made of a so-called substantially U-shaped non-magnetic material having a bent portion 6a which is a folded portion. The frame 6 has a bent portion 6a, a first frame 6b (long portion) extended from one end of the bent portion 6a, and a second frame 6c extended from the other end of the bent portion 6a.

One end of the frame 6 (the end of the first frame 6b) is fixed to the vibration source 10. The other end of the frame 6 (the end of the second frame 6c) is connected to one end 3b on the side opposite to the tip 3a of the diaphragm 3.
As shown in FIG. 1B, the first magnet 7 and the second magnet 8 are line-symmetrical with respect to the axial direction (X direction) of the coil 5 in the width direction (centered on the axis of the coil 5). They are arranged so as to be separated from each other along the Y direction.
Further, the side length L of the magnetostrictive element 2 parallel to the axis of the coil 5 and the side length L of the first magnet 7 and the second magnet 8 are substantially the same. As a result, the surfaces through which the magnetic flux passes between the first magnet 7 and the second magnet 8 and the magnetostrictive element 2 can be aligned with each other.
Further, the first magnet 7 is arranged so that the upper surface is the N pole and the lower surface is the S pole, and the second magnet 8 is arranged so that the upper surface is the S pole and the lower surface is the N pole. There is.
As described above, the power generation device 1 has a cantilever structure as a whole.

Next, the reflux of the magnetic flux in the power generation device 1 will be described with reference to FIG. 1C. Generally, the magnetic field generated by a magnet has a property of drawing a magnetic field line that returns from the north pole to the south pole. In FIG. 1C, the magnetic path 11 is a magnetic path formed by the first magnet 7, the second magnet 8, and the magnetostrictive element 2. As shown in FIG. 1C, for example, the spatial distance between the first magnet 7 and the second magnet 8 is longer than the spatial distance between the first magnet 7 and the magnetostrictive element 2, and the second magnet 8 It is longer than the spatial distance between the magnetostrictive element 2 and the magnetostrictive element 2. Further, the first magnet 7 and the second magnet 8 are provided at positions in FIGS. 1B and 1C that do not overlap with the magnetostrictive element 2 when viewed from the Z direction. As a result, the magnetic resistance between the first magnet 7 and the second magnet 8 becomes larger than the magnetic resistance of the path passing through the magnetostrictive element 2, and a short-circuit magnetic path not passing through the magnetostrictive element 2 is formed. Can be suppressed. Specifically, the magnetic flux 12 emitted from the north pole of the first magnet 7 enters the magnetostrictive element 2 through the gap 11a between the first magnet 7 and the magnetostrictive element 2. Then, the magnetic flux 12 that has passed through the magnetostrictive element 2 enters the S pole of the second magnet 8 through the gap 11a between the magnetostrictive element 2 and the second magnet 8. Further, the magnetic flux 12 passes through the magnetic plate 9 from the north pole of the second magnet 8 and returns to the south pole of the first magnet 7. As described above, the magnetic path 11 is a closed magnetic path in which the magnetic flux 12 returns along the YZ plane. The gap 11a between the first magnet 7 and the magnetostrictive element 2 and the gap 11a between the magnetostrictive element 2 and the second magnet 8 are narrowed, for example, within a range that does not interfere with the vibration of the diaphragm 3. You may keep it.

Next, each component of the power generation device 1 will be described in more detail.

[Morcostrictive element 2]
As the magnetostrictive element 2, a material having a characteristic of generating a magnetic flux change when it expands or contracts due to stress can be used. Examples of this material include TbFe ₂ (terbium-iron alloy), DyFe ₂ (disprocium-iron alloy), HoFe ₂ (formium-iron alloy), Galphenol (gallium-iron alloy), and Terfenol-D (terbium-iron alloy). Disprosium-iron alloy), FeSiB (iron-silicon-boron amorphous alloy) and the like.
The magnetostrictive element 2 has, for example, a rectangular plate shape long in the X direction, but is not limited to this, and may be, for example, a rectangular parallelepiped, a cube, a cylinder, or the like.
The magnetostrictive element 2 may be either a single crystal or a polycrystal, but the single crystal is preferable because the magnetic flux generated by the magnetostrictive effect is larger.

[Diaphragm 3, weight 4]
The diaphragm 3 and the weight 4 are provided so that the power generation device 1 can generate power according to the vibration conditions of the vibration source 10. The diaphragm 3 has a free end 3a. A weight 4 may be provided at the free end 3a.
An object has a unique frequency. Therefore, the vibration condition of the diaphragm 3 is adjusted to the vibration condition of the vibration source 10, and the vibration plate 3 resonates with the vibration source 10, so that the power generation device 1 can vibrate greatly and a large amount of power can be obtained. That is, it is preferable that the diaphragm 3 and the weight 4 have a structure matched to the vibration frequency of the vibration source 10.
For example, the resonance frequency of the power generation device 1 decreases when the weight 4 is made heavier or the diaphragm 3 is made longer. Using this characteristic, the resonance frequency of the power generation device 1 can be adjusted. If a desired natural frequency can be obtained simply by adjusting the length of the diaphragm 3, the weight 4 may not be provided.

Further, since it is not necessary to pass the magnetic flux through the diaphragm 3, it is preferable that the diaphragm 3 is a non-magnetic material, and for example, a plate-shaped SUS304 can be used.
The material of the weight 4 is not particularly limited, but from the viewpoint of miniaturization, the size of the weight 4 can be reduced by using a material having a high density (for example, tungsten or the like). Further, since it is not necessary to pass the magnetic flux through the weight 4, the material of the weight 4 is more preferably a non-magnetic material.

[Coil 5]
The coil 5 generates a voltage in proportion to the time change of the magnetic flux passing through the magnetostrictive element 2 according to the law of electromagnetic induction. Further, in order to maintain the reliability of the power generation device 1, the coil 5 is formed of the magnetostrictive element 2 and the diaphragm 3 via an insulating resin or the like (not shown) with the first direction (X direction) as an axis. It is wound around fixedly. The coil 5 may be wound around the magnetostrictive element 2 and the diaphragm 3 with a space for ensuring electrical insulation.
As the material of the coil 5, for example, copper wire or aluminum wire can be used, but the material is not limited thereto. Further, the magnitude of the voltage and the magnitude of the resistance can be adjusted by changing the number of turns and the wire diameter of the coil 5. Both ends of the winding of the coil 5 are electrically connected to a rectifier or the like (not shown) as needed. Thereby, the electric energy obtained by the vibration can be taken out.

[Frame 6]
The frame 6 transmits the vibration from the vibration source 10 to the magnetostrictive element 2 and the diaphragm 3. Further, since the frame 6 does not function as the magnetic path 11 shown in FIG. 1C, it is preferable to use a non-magnetic material such as SUS304 so that magnetic flux does not flow in an unnecessary portion. The frame 6 may have, for example, rigidity and elasticity so that it can vibrate. The frame 6 may be formed by bending one plate, or may be formed by joining (for example, screwing) a plurality of members. Further, in the present embodiment, the diaphragm 3 and the frame 6 are treated as separate members, but when the same material is used, there is no problem even if one plate is molded in the same manner. ..

[First magnet 7, second magnet 8]
The first magnet 7 and the second magnet 8 are arranged to apply a magnetic field to the magnetostrictive element 2 from a direction along a plane (YZ plane) intersecting the first direction (X direction). .. As shown in FIG. 10, the shape and material of the first magnet 7 and the second magnet 8 are not limited as long as they are the optimum magnetic fields capable of improving the amount of power generation. For example, neodymium-based permanent magnets can be used, but ferrite-based and cobalt-based permanent magnets may also be used. Further, the size is not limited as long as the arrangement relationship described with reference to FIGS. 1A and 1B or the magnetic path described with reference to FIG. 1C is not broken.

[Magnetic plate 9]
The magnetic plate 9 is a part of the magnetic path 11 for refluxing the magnetic flux 12 from the second magnet 8 to the first magnet 7, as described with reference to FIG. 1C. Therefore, as the material of the magnetic plate 9, it is preferable to use an iron-based material having a high magnetic permeability, for example, cold-rolled steel (for example, SPCC: JIS G3141) or the like.

<Effect>
The effect of the power generation device 1 (the effect of reducing the distribution of the magnetic field applied to the magnetostrictive element 2) according to the first embodiment will be described. Here, the effect of the power generation device 1 will be described by comparing the power generation device 1 of the present embodiment with a reference example.

[evaluation]
In order to analyze the magnetic flux in detail, the effects of the first embodiment and the reference example were verified using electromagnetic field analysis software (JMAG: manufactured by JSOL). This verification result will be described with reference to FIGS. 2A and 2B. FIG. 2A is a schematic perspective view showing the positional relationship between the magnetostrictive element 2, the first magnet 7, the second magnet 8, and the magnetic plate 9. FIG. 2B shows a graph showing the magnetic field distribution applied to the magnetostrictive element 2.
First, each component used in the analysis will be described. The magnetostrictive element 2 is a rectangle having a length (X direction) of 26 mm, a width (Y direction) of 8 mm, and a thickness (Z direction) of 0.5 mm. Further, the first magnet 7 and the second magnet 8 are rectangular shapes having a length (X direction) of 26 mm, a width (Y direction) of 2 mm, and a thickness (Z direction) of 2 mm, and as described in FIG. 1B, the coils. The axes 5 were arranged symmetrically along the width direction (Y direction). The magnetic plate 9 has a length (X direction) of 26 mm, a width (Y direction) of 12 mm, and a thickness (Z direction) of 1 mm, and the first magnet 7 and the second magnet 8 are arranged at both ends in the width direction. It was configured. Further, when a non-magnetic material is used for the diaphragm 3, the weight 4, and the frame 6, the description of the dimensions and the illustration of the shape are omitted because they have almost no influence on the magnetic field.

In the graph of FIG. 2B, the horizontal axis shows the position (mm) of the magnetostrictive element 2 in the length direction (X direction), and the vertical axis shows the magnetic field index (no unit). Further, on the horizontal axis, the end of the magnetostrictive element 2 on the bent portion 6a side of the frame 6 is 0 mm, and the end of the magnetostrictive element 2 on the free end side is 26 mm. The magnetic field on the vertical axis indicates the magnetic field on the outermost surface of the magnetostrictive element 2, and is the center of the magnetostrictive element 2 in the width direction ((a) in FIG. 2A) and a position 1 mm inward from the left and right ends (FIG. The magnetic fields of (b) and (c) in 2A were graphed. Further, regarding handling the magnetic field on the outermost surface of the magnetostrictive element 2, there is almost no distribution in the thickness direction, so that there is no problem in explaining the effect of the present embodiment. Further, the magnetic field is not an absolute value, but the magnitude of the magnetic field at the position of 0 mm along the X direction of the magnetostrictive element 2 (a) is set to "1", and the magnitude of each magnetic field is set with respect to the magnitude of the magnetic field. It is shown as a relative magnetic field index. This is because the optimum absolute value of the magnetic field differs depending on the characteristics of the magnetostrictive element 2 described with reference to FIG. Since the object of the present disclosure is to reduce the magnetic field distribution in the magnetostrictive element, the effect may be expressed as a magnetic field index.

As shown in the graph of FIG. 2B, it can be seen that the magnetic field index rises from 0 mm toward the center along the X direction, and when it exceeds the center, the magnetic field index tends to approach 1 again. This has the same tendency in any of (a), (b), and (c) indicating the position of the surface of the magnetostrictive element 2 described above. As for the distribution of the magnetic field, the relative magnetic field index is in the range of 0.94 to 1.70.

[Difference from reference example]
Next, the power generation device 1a according to the reference example of the present embodiment will be described.
FIG. 3A is a schematic side view of the power generation device 21 according to the reference example. The difference in configuration from the power generation device according to the first embodiment is that one magnet 27 is used and the magnetic plate 9 is not arranged. As shown in FIG. 3A, the magnet 27 is arranged in the first frame 26b of the frame 26 at a position not facing the magnetostrictive element 22. At this time, the frame 26 uses a magnetic material as a material for the magnetic path 31 described below.
FIG. 3B is a schematic view showing how the magnetic flux of the power generation device 21 according to the reference example with respect to the first embodiment of the present disclosure returns. In the case of the configuration as in the reference example, the magnetic flux 32 emitted from the north pole of the magnet 27 passes through the gap 31a and passes through the inside from the end of the magnetostrictive element 22. Further, when exiting from the magnetostrictive element 22, the frame 26 passes through the end of the second frame 26c of the frame 26. After that, the magnetic flux 32 becomes a closed magnetic path that returns to the S pole of the magnet 27. In this case, in the power generation device 21 according to the reference example, the closed magnetic path is configured along the ZX plane.
FIG. 4A is a schematic perspective view of the power generation device 21 according to the reference example for the first embodiment of the present disclosure. FIG. 4B is a graph showing the magnetic field distribution along the three lines of the magnetostrictive element 22 in the power generation device 21 of FIG. 4A. The dimensions of the magnetostrictive element 22 are the same as those in the first embodiment, but the magnet 27 is a rectangle having a length of 10 mm, a width of 8 mm, and a thickness of 2 mm.

In the graph of FIG. 4B, the horizontal axis shows the position (mm) of the magnetostrictive element 22 in the length direction (X direction), and the vertical axis shows the magnetic field index (no unit). Further, on the horizontal axis, the end of the magnetostrictive element 22 on the bent portion 26a side of the frame 26 is 0 mm, and the end of the magnetostrictive element 22 on the free end side is 26 mm. The magnetic field on the vertical axis indicates the magnetic field on the outermost surface of the magnetostrictive element 22, and is the center in the width direction of the magnetostrictive element 22 ((a) in FIG. 4A) and a position 1 mm inward from the left and right ends (FIG. The magnetic fields of (b) and (c) in 4A were graphed. Further, regarding handling the magnetic field on the outermost surface of the magnetostrictive element 22, there is almost no distribution in the thickness direction, so that there is no problem in explaining the effect of the present embodiment. Further, the magnetic field is not an absolute value, but the magnitude of the magnetic field at the position of 0 mm along the X direction of the magnetostrictive element 22 (a) is set to "1", and the magnitude of each magnetic field is set with respect to the magnitude of the magnetic field. It is shown as a relative magnetic field index.

As the graph of FIG. 4B shows, the magnetic field index rises from 0 mm toward the center along the X direction, and becomes steeper as it approaches the magnet. This is because, as described above, the magnetic field is inversely proportional to the distance from the magnet, and (a), (b), and (c) indicating the position of the surface of the magnetostrictive element 22 all have almost the same tendency. .. The distribution of the magnetic field in the reference example is a relative magnetic field index in the range of 0.65 to 8.51.
As described above, the distribution of the magnetic field of the magnetostrictive element 2 in the power generation device according to the first embodiment shown in FIG. 2B has a magnetic field index in the range of 0.94 to 1.70. On the other hand, the distribution of the magnetic field of the magnetostrictive element 22 in the power generation device according to the reference example shown in FIG. 4B has a magnetic field index in the range of 0.65 to 8.51 as described above.

As described above, from the results of FIGS. 2B and 4B, it can be seen that the configuration of the power generation device according to the first embodiment can reduce the magnetic field distribution in the magnetostrictive element as compared with the power generation device according to the reference example. Specifically, in the first embodiment, the magnetic field is applied to the magnetostrictive element not along the ZX plane including the longitudinal direction (X direction) but along the YZ plane including the width direction (Y direction). It is characterized by doing. As a result, in the power generation device according to the first embodiment, the magnetic field distribution along the X direction can be reduced.
Further, in particular, in the reference example, since the part of the magnetostrictive element 22 on the side close to the magnet tends to enter the large saturation region of the magnetic field in FIG. 10, the magnetic flux density change ΔB is almost the same even when tension or compression due to vibration is applied. Therefore, the magnetostrictive element 22 cannot be used effectively, and it is difficult to extract electric power. Conversely, the power generation device according to the first embodiment can significantly improve the portion of the magnetostrictive element 2 that contributes to power generation, and is expected to increase the amount of power generation.

(Embodiment 2)
The power generation device 1a according to the second embodiment of the present disclosure will be described.
<Structure>
First, the configuration of the power generation device 1a according to the second embodiment will be described with reference to FIGS. 5A and 5B. FIG. 5A is a schematic side view of the power generation device 1a according to the second embodiment. FIG. 5B is a schematic top view of the power generation device 1 according to the second embodiment. The second embodiment is different from the first embodiment in that the first magnets 7a and 7b and the second magnets 8a and 8b are separately arranged. The first magnets 7a and 7b and the second magnets 8a and 8b are arranged so as to be separated from each other along the X direction with respect to the left-right direction (Y direction) in FIG. 5B. Is the same for the first magnets 7a and 7b and the second magnets 8a and 8b. Since the other structures are the same as those in the first embodiment, the description thereof will be omitted. The same applies to the return path of magnetic flux.

<Effect>
[evaluation]
Similar to the first embodiment, the effect of the power generation device according to the second embodiment was verified by using the electromagnetic field analysis software (JMAG: manufactured by JSOL). This verification result will be described with reference to FIGS. 6A and 6B.
FIG. 6A is a schematic perspective view showing the positional relationship between the magnetostrictive element 2, the first magnets 7a and 7b, the second magnets 8a and 8b, and the magnetic plate 9. FIG. 6B shows a graph showing the magnetic field distribution applied to the magnetostrictive element 2.
First, each component used in the analysis will be described. The first magnets 7a and 7b and the second magnets 8a and 8b have a rectangular parallelepiped shape having a length of 11 mm, a width of 2 mm and a thickness of 2 mm. Other members are the same as those in the first embodiment. The same characteristics were used for the strength of the magnet used in electromagnetic field analysis.

In the graph of FIG. 6B, the horizontal axis shows the position (mm) of the magnetostrictive element 2 in the length direction (X direction), and the vertical axis shows the magnetic field index (no unit). Further, on the horizontal axis, the end of the magnetostrictive element 2 on the bent portion 6a side of the frame 6 is 0 mm, and the end of the magnetostrictive element 2 on the free end side is 26 mm. The magnetic field on the vertical axis indicates the magnetic field on the outermost surface of the magnetostrictive element 2, and is the center of the magnetostrictive element 2 in the width direction ((a) in FIG. 6A) and a position 1 mm inward from the left and right ends (FIG. 6A). The magnetic fields of (b) and (c) in 6A were graphed.
As shown in the graph of FIG. 6B, it can be seen that the central portion of the magnetostrictive element 2 has two peaks in which the relative magnetic field index tends to decrease. This is the effect of dividing the first magnets 7a and 7b and the second magnets 8a and 8b, and the magnetic field index is distributed in the range of 1.00 to 1.58. The distribution of the magnetic field can be further reduced as compared with the first embodiment.

(Embodiment 3)
The power generation device 1b according to the third embodiment of the present disclosure will be described.
<Structure>
First, the configuration of the power generation device 1b according to the third embodiment will be described with reference to FIGS. 7A and 7B. FIG. 7A is a schematic side view of the power generation device 1b according to the third embodiment. FIG. 7B is a schematic top view of the power generation device 1b according to the third embodiment. The third embodiment is different from the first embodiment in that the first magnets 7a, 7b, 7c and the second magnets 8a, 8b, 8c are separately arranged. The first magnets 7a, 7b, 7c and the second magnets 8a, 8b, 8c are arranged so as to be separated from each other in the left-right direction in FIG. 7b, 7c, and the second magnets 8a, 8b, 8c are the same. Since the other structures are the same as those in the first embodiment, the description thereof will be omitted. The same applies to the return path of magnetic flux.

<Effect>
[evaluation]
Similar to the first embodiment, the effect of the third embodiment was verified by using the electromagnetic field analysis software (JMAG: manufactured by JSOL). This verification result will be described with reference to FIGS. 8A and 8B.
FIG. 8A is a schematic perspective view showing the positional relationship between the magnetostrictive element 2, the first magnets 7a, 7b, 7c, the second magnets 8a, 8b, 8c, and the magnetic plate 9. FIG. 8B shows a graph showing the magnetic field distribution applied to the magnetostrictive element 2.

First, each component used in the analysis will be described. The first magnets 7a, 7b, 7c and the second magnets 8a, 8b, 8c have a rectangular parallelepiped shape having a length of 8 mm, a width of 2 mm, and a thickness of 2 mm. Other members are the same as those in the first embodiment. The same characteristics were used for the strength of the magnet used in electromagnetic field analysis.

In the graph of FIG. 8B, the horizontal axis shows the position (mm) of the magnetostrictive element 2 in the length direction (X direction), and the vertical axis shows the magnetic field index (no unit). Further, on the horizontal axis, the end of the magnetostrictive element 2 on the bent portion 6a side of the frame 6 is 0 mm, and the end of the magnetostrictive element 2 on the free end side is 26 mm. The magnetic field on the vertical axis indicates the magnetic field on the outermost surface of the magnetostrictive element 2, and is the center in the width direction of the magnetostrictive element 2 ((a) in FIG. 8A) and a position 1 mm inward from the left and right ends (FIG. The magnetic fields of (b) and (c) in 8A were graphed.

As shown in the graph of FIG. 8B, as in the first embodiment, it can be seen that the magnetic field index tends to increase from 0 mm toward the center, and when the magnetic field index exceeds the center, the magnetic field index tends to approach 1 again. .. This has the same tendency in any of (a), (b), and (c) indicating the position of the surface of the magnetostrictive element 2 described above. As for the distribution of the magnetic field, the magnetic field index is in the range of 1.00 to 1.72, and almost the same effect as that of the first embodiment can be obtained.

As described above, in the power generation devices 1 of the first to third embodiments, a uniform magnetic flux density change ΔB can be obtained by reducing the magnetic field distribution applied to the magnetostrictive element 2, and the amount of power generation is improved. Can be made to.

It should be noted that the present disclosure includes appropriately combining any of the various embodiments and / or embodiments described above, and the respective embodiments and / or embodiments. The effect of the example can be achieved. Further, the description is not limited to the above embodiment, and various modifications can be made without departing from the gist thereof.

According to the power generation device according to the present disclosure, it is possible to improve the power generation efficiency. As a result, in the IoT (Internet of Things), which is expected to be used in many fields such as industrial fields, crime prevention / disaster prevention fields, social infrastructure fields, medical / welfare fields, etc., it can be applied to wireless sensor modules, which are key components. Is especially useful.

1, 1a, 1b, 21 Power generation device 2, 22 Magnetic strain element 3, 23 Vibrating plate 4, 24 Weight 5, 25 Coil 6, 26 Frame 6a Bending part 6b 1st frame 6c 2nd frame 7, 7a, 7b, 7c One magnet 8, 8a, 8b, 8c Second magnet 9 Magnetic plate 10 Vibration source 11, 31 Magnetic path 11a, 31a Void 12, 32 Magnetic flux 27 Magnet 100 Power generator 101 Magnetic distortion element 102 Frame yoke 103 Magnetic part 104 Back yoke 105 Magnet 106 Vibration plate 107 Weight 108 Coil 109 Vibration source 110 Metal fittings

Claims (6)

A diaphragm that extends in the first direction and has a free end,
A plate-shaped magnetostrictive element extending in the first direction and made of a magnetostrictive material provided on one surface of the diaphragm.
A coil provided around the magnetostrictive element and
A frame made of a non-magnetic material, one end of which is connected to one end of the diaphragm opposite to the free end and the other end of which is connected to a vibration source.
A first magnet and a second magnet that apply a magnetic field to the magnetostrictive element from a direction along a surface intersecting the first direction.
A magnetic plate arranged on the frame and mounting the first magnet and the second magnet,
With
The first magnet and the second magnet are separated from each other along a second direction intersecting with the first direction so as to be substantially line-symmetrical with respect to the axis of the coil. It is placed on a magnetic plate and
Further, the polarity of the first magnet on the magnetic plate side and the polarity of the second magnet on the magnetic plate side are opposite to each other.
Power generator. The power generation device according to claim 1, wherein the first magnet or the second magnet is a group of magnets divided into two or more along the first direction. The power generation device according to claim 2, wherein the magnet groups are arranged at equal intervals. The spatial distance between the first magnet and the second magnet is longer than the spatial distance between the first magnet and the magnetostrictive element, and is greater than the spatial distance between the second magnet and the magnetostrictive element. Long,
Any of claims 1 to 3, wherein the first magnet and the second magnet do not overlap with the magnetostrictive element when viewed from the first direction and the third direction orthogonal to the second direction. The power generation device according to item 1. The power generation device according to any one of claims 1 to 4, wherein the coil is wound around the magnetostrictive element and the diaphragm with the first direction as an axis. The power generation device according to any one of claims 1 to 5, further comprising a weight arranged at the free end of the diaphragm.

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