U.S. patent application number 17/235427 was filed with the patent office on 2021-08-05 for magnetostriction element and magnetostriction-type vibration powered generator using same.
The applicant listed for this patent is Panasonic Intellectual Property Management Co., Ltd.. Invention is credited to Taichi NAKAMURA, Kazuki SAKAI.
Application Number | 20210242809 17/235427 |
Document ID | / |
Family ID | 1000005526944 |
Filed Date | 2021-08-05 |
United States Patent
Application |
20210242809 |
Kind Code |
A1 |
NAKAMURA; Taichi ; et
al. |
August 5, 2021 |
MAGNETOSTRICTION ELEMENT AND MAGNETOSTRICTION-TYPE VIBRATION
POWERED GENERATOR USING SAME
Abstract
A magnetostriction-type vibration powered generator including a
power generating section and a frame joined to the power generating
section. The power generating section includes a diaphragm formed
of non-magnetic material and disposed at a first end of the power
generating section, a magnetostriction element disposed at a second
end of the power generating section; and a coil wrapped around the
magnetostriction element along the longitudinal direction. The
frame includes a frame body formed of a magnetic material and
joined to a second end of the power generating section. A magnet is
provided on the frame body so as to face the magnetostriction
element of the power generating section.
Inventors: |
NAKAMURA; Taichi; (Osaka,
JP) ; SAKAI; Kazuki; (Osaka, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Panasonic Intellectual Property Management Co., Ltd. |
Osaka |
|
JP |
|
|
Family ID: |
1000005526944 |
Appl. No.: |
17/235427 |
Filed: |
April 20, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
16460145 |
Jul 2, 2019 |
11012007 |
|
|
17235427 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 41/125 20130101;
H01L 41/20 20130101; H02N 2/188 20130101; C22C 38/002 20130101 |
International
Class: |
H02N 2/18 20060101
H02N002/18; H01L 41/12 20060101 H01L041/12; H01L 41/20 20060101
H01L041/20 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 30, 2018 |
JP |
2018-160992 |
Claims
1. A magnetostriction-type vibration powered generator comprising a
power generating section, and a frame joined to the power
generating section, the power generating section having a first end
and a second end, and including: a diaphragm formed of a
non-magnetic material and disposed at the first end of the power
generating section; a magnetostriction element disposed at the
second end of the power generating section, the magnetostriction
element comprising a magnetostrictive material that is a
monocrystalline alloy represented by the following formula (1),
Fe.sub.(100-.alpha.-.beta.) Ga.sub..alpha.X.sub..beta., Formula (1)
wherein .alpha. and .beta. represent Ga content (at %) and X
content (at %), respectively, X is at least one element selected
from a group consisting of Sm, Eu, Gd, Tb, Dy, Cu, and C, and the
formula satisfies 5.ltoreq..alpha..ltoreq.40, and
0.ltoreq..beta..ltoreq.1, the magnetostriction element having a
longitudinal direction along which the magnetostriction element
extends between opposing first and second ends, the
magnetostriction element having a <100> crystal orientation
of the monocrystalline alloy along a direction parallel to the
longitudinal direction, and having a Ga concentration gradient that
decreases in a direction from the second end to the first end
disposed at the second end of the power generating section; and a
coil wrapped around the magnetostriction element along the
longitudinal direction, the frame having a first end and a second
end, and including: a frame body formed of a magnetic material and
joined to the second end of the power generating section at the
first end of the frame, the frame body extending between the first
end and the second end of the frame; and a magnet provided on the
frame body so as to face the magnetostriction element of the power
generating section, the magnetostriction element being disposed in
such an orientation that the direction from the second end to the
first end of the power generating section corresponds to the
longitudinal direction of the magnetostriction element, and that
the magnetostriction element joins the diaphragm at the first end
of the magnetostriction element.
2. The magnetostriction-type vibration powered generator according
to claim 1, wherein the power generating section and the frame have
a C-shape as a whole.
3. The magnetostriction-type vibration powered generator according
to claim 1, wherein the magnet is provided on the frame body so as
to face the magnetostriction element at the first end of the
magnetostriction element.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a divisional application of U.S.
application Ser. No. 16/460,145 filed on Jul. 2, 2019 and claims
the benefit of foreign priority of Japanese patent application
2018-160992 filed on Aug. 30, 2018, the contents of which are
incorporated herein by reference.
TECHNICAL FIELD
[0002] The technical field relates to a magnetostriction element
formed of a magnetostrictive material, and to a
magnetostriction-type vibration powered generator using same.
BACKGROUND
[0003] Recent years have seen the arrival of the Internet of things
(IoT), a world where "things" equipped with autonomous
communication functions automatically control one another by
exchanging information. The spread of IoT means a society with
increasing numbers of IoT devices featuring communication
functions. IoT devices, such as sensors, require a power supply to
operate. However, the needs for wirings and service time, and the
cost make it difficult to provide power supplies for these
proliferating numbers of devices. This has created a need for a
power supply technology suited for IoT devices in the coming era of
IoT. Against this background, an important consideration is a
technology called "energy harvesting", a process by which small
amounts of energy from the everyday environment are converted into
electrical power. Vibration is a form of energy source that is
constantly produced by moving objects such as automobiles, trains,
machinery, and humans in many places, and represents an energy
source that is not influenced by weather or climate. It is
therefore envisioned that a system that enables vibration-based
power to be used as a power supply to applications coupled to
movement of moving objects such as above can open the door to more
effective IoT.
[0004] Vibration-based power generation can be divided into four
categories: magnetostrictive, piezoelectric, electrostatic
induction, and electromagnetic induction. In magnetostrictive power
generation, a leakage magnetic flux due to a change in magnetic
field inside a magnetostrictive material in response to applied
stress is converted into electrical energy through a coil wrapped
around the magnetostrictive material. The magnetostrictive power
generation involves a smaller internal resistance, and generates
more power than the other types of vibration-based power
generation. Another characteristic of the magnetostrictive power
generation is the desirable durability due to the metal alloy used
as magnetostrictive material. This makes the magnetostrictive power
generation a desirable mode of power generation that could overcome
an issue associated with magnetostriction-type vibration powered
generators or elements, namely, the durability of
magnetostriction-type vibration powered generators or elements.
[0005] An example of a magnetostriction-type vibration powered
generator is one having a cantilever beam structure. A traditional
magnetostriction-type vibration powered generator having a
cantilever beam structure has a magnetostrictive rod (or a
magnetostriction element) formed of a magnetostrictive material; a
coil wrapped around the magnetostrictive rod; a magnetic rod
disposed parallel to the magnetostrictive rod; a frame curved in a
U shape; and a magnet attached to inside of the frame (see
WO2015/141414). The frame is a magnetic material with two ends. One
of the ends on either side of the U-shaped bent portion is a fixed
end, and the other end is a free end. In this way, a part of the
frame works as a back yoke, and the frame forms an air gap between
the magnet and the inner surface of the frame where the magnet is
not attached.
[0006] In such a cantilever beam structure having a fixed end, the
magnetostrictive rod is subjected to tensile and compressional
stress when an external force (vibration) is applied within a
horizontal plane, and this creates an alternating magnetic field in
the magnetic field lines. Voltage is extracted in the form of
electrical energy as the coil generates voltage in accordance with
the law of electromagnetic induction, which states that voltage
occurs in proportion to changes occurring in magnetic flux density
over time.
[0007] In a magnetostriction-type vibration powered generator,
power output P is represented by P=NId/dt(.intg.iBdA), and power
density E is represented by E=P/v. Here, N is the number of turns
in the coil, I is the value of the current through the coil, B is
the magnetic flux density of the magnetostriction element, A is the
cross sectional area of the magnetostriction element, and v is the
volume of the magnetostriction-type vibration powered generator.
However, in the magnetostriction-type vibration powered generator
above, the stress exerted on the magnetostriction element in
response to an external force (vibration) applied within a
horizontal plane in the cantilever beam structure is greater at the
fixed end than at the free end, and this creates a stress
distribution as a result of the stress not being exerted throughout
the magnetostriction element in a uniform fashion. The stress
distribution creates a distribution in the magnetic field lines
running inside the magnetostriction element, and changes in the
magnetic flux density B of the magnetostriction element become
smaller as a whole, with the result that the power output P also
becomes smaller. That is, the power density E (power output P per
volume) is too small to achieve the high output (high power output)
needed for IoT. Indeed, the power density E of the
magnetostriction-type vibration powered generator needs to be
improved for practical applications. For example, a
magnetostriction-type vibration powered generator requires a
consumed power density of about 1.0 mW/cm.sup.3 in applications
such as tire air pressure monitoring systems, and sensor networks
for factories.
SUMMARY OF THE INVENTION
[0008] The present disclosure is intended to provide a
magnetostriction element and a magnetostriction-type vibration
powered generator having a large power output and a high power
density.
[0009] According to a first gist of the present disclosure, there
is provided a magnetostriction element comprised of a
magnetostrictive material that is a monocrystalline alloy
represented by the following formula (1),
Fe .sub.(100-.alpha.-.beta.) Ga.sub..alpha.X.sub..beta., Formula
(1)
wherein .alpha. and .beta. represent the Ga content (at % ) and the
X content (at %), respectively, X is at least one element selected
from the group consisting of Sm, Eu, Gd, Tb, Dy, Cu, and C, and the
formula satisfies 5.ltoreq..alpha..ltoreq.40, and
0.ltoreq..beta..ltoreq.1,
[0010] the magnetostriction element having a longitudinal direction
along which the magnetostriction element extends between opposing
first and second ends,
[0011] the magnetostriction element having the <100> crystal
orientation of the monocrystalline alloy along a direction parallel
to the longitudinal direction, and having a Ga concentration
gradient that decreases in a direction from the second end to the
first end.
[0012] In an aspect of the first gist of the present disclosure,
the magnetostriction element may be plate-like in shape.
[0013] In an aspect of the first gist of the present disclosure,
the Ga concentration may be 14 at % or more and 16 at % or less at
the first end, and 17 at % or more and 19 at % or less at the
second end.
[0014] In an aspect of the first gist of the present disclosure,
the Ga concentration may decrease at an average rate of 0.15 at %
or more and 0.2 at % or less per millimeter in the direction from
the second end to the first end.
[0015] In an aspect of the first gist of the present disclosure, X
may be at least one element selected from the group consisting of
Sm, Cu, and C, and the formula may satisfy
14.ltoreq..alpha..ltoreq.19, and 0.5.ltoreq..beta..ltoreq.1.
[0016] According to a second gist of the present disclosure, there
is provided a magnetostriction-type vibration powered generator
comprising a power generating section, and a frame joined to the
power generating section,
[0017] the power generating section having a first end and a second
end, and including: [0018] a diaphragm formed of a non-magnetic
material and disposed at the first end of the power generating
section; [0019] the magnetostriction element of claim 1 disposed at
the second end of the power generating section; and [0020] a coil
wrapped around the magnetostriction element along the longitudinal
direction,
[0021] the frame having a first end and a second end, and
including:
[0022] a frame body formed of a magnetic material and joined to the
second end of the power generating section at the first end of the
frame, the frame body extending between the first end and the
second end of the frame; and
[0023] a magnet provided on the frame body so as to face the
magnetostriction element of the power generating section,
[0024] the magnetostriction element being disposed in such an
orientation that the direction from the second end to the first end
of the power generating section corresponds to the longitudinal
direction of the magnetostriction element, and that the
magnetostriction element joins the diaphragm at the first end of
the magnetostriction element.
[0025] In an aspect of the second gist of the present disclosure,
the power generating section and the frame may have a C-shape as a
whole.
[0026] In an aspect of the second gist of the present disclosure,
the magnet may be provided on the frame body so as to face the
magnetostriction element at the first end of the magnetostriction
element.
[0027] The present disclosure has provided a magnetostriction
element and a magnetostriction-type vibration powered generator
having a large power output and a high power density.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] FIG. 1 is a schematic diagram of a magnetostriction element
of an embodiment of the present disclosure.
[0029] FIG. 2 is a graph schematically representing a distribution
of Ga concentration in the magnetostriction element of the
embodiment of the present disclosure.
[0030] FIG. 3 is a cross sectional view representing a
magnetostriction-type vibration powered generator equipped with the
magnetostriction element of the embodiment of the present
disclosure.
[0031] FIG. 4 is a perspective view representing the
magnetostriction-type vibration powered generator equipped with the
magnetostriction element of the embodiment of the present
disclosure.
DETAILED DESCRIPTION OF EMBODIMENTS
[0032] The following describes a magnetostriction element, and a
method of manufacture thereof according to an embodiment of the
present disclosure. A magnetostriction-type vibration powered
generator provided with the magnetostriction element is also
described. It is to be noted that the present disclosure is not
limited to the embodiments below.
Magnetostriction Element
[0033] The magnetostriction element of the present embodiment is
formed of a magnetostrictive material that is a monocrystalline
alloy represented by the following formula (1),
Fe .sub.(100-.alpha.-.beta.) Ga.sub..alpha.X.sub..beta., Formula
(1)
wherein .alpha. and .beta. represent the Ga content (at %) and the
X content (at %), respectively, X is at least one element selected
from the group consisting of Sm, Eu, Gd, Tb, Dy, Cu, and C, and the
formula satisfies 5.ltoreq..alpha..ltoreq.40, and
0.ltoreq..beta..ltoreq.1.
[0034] The magnetostriction element has a longitudinal direction
along which the magnetostriction element extends between opposing
first and second ends.
[0035] The magnetostriction element has the <100> crystal
orientation of the monocrystalline alloy along a direction parallel
to the longitudinal direction, and has a Ga concentration gradient
that decreases in a direction from the second end to the first
end.
[0036] The FeGaX monocrystalline alloy of the formula (1) includes
an FeGa binary alloy because .beta. can take a value of 0.
[0037] Preferably, X in the formula (1) is at least one element
selected from the group consisting of Sm, Cu, and C, and the
formula satisfies 14.ltoreq..alpha..ltoreq.19, and
0.5.ltoreq..beta..ltoreq.1. In another embodiment, the formula (1)
satisfies 14.ltoreq..alpha..ltoreq.19, and .beta.=0, preferably
17.ltoreq..alpha..ltoreq.18.4, and .beta.=0.
[0038] The magnetostriction element of the present embodiment may
have any appropriately selected shape. For example, the
magnetostriction element of the present embodiment may have a
rectangular shape (or a plate-like shape), a cubic shape, a
columnar shape, a polygonal column shape, or some other solid
shape. The preferred shape is a plate-like shape. In the case of a
plate-like shape, the magnetostriction element may have, for
example, cross sectional dimensions measuring 5 mm to 20 mm in
width, and 1 mm to 3 mm in height, preferably about 10 mm in width,
and about 1 mm in height. The longitudinal length (the distance
between the opposing ends along the longitudinal direction) may be
10 mm to 30 mm, preferably about 30 mm, more preferably about 20
mm.
[0039] As used herein, "Ga concentration" represents a fraction of
the number of Ga atoms with respect to the total number of atoms in
the alloy, and has a value in at % (atomic percent). More
specifically, "Ga concentration" is a Ga content as measured by
analysis of the alloy using an electron probe microanalyzer (EPMA).
Similarly, the concentrations or contents of the other elements
(for example, Fe, Sm, Eu, Gd, Tb, Dy, Cu, and C) in the alloy are
measured values in at % (atomic percent) obtained by using the same
method. It is to be noted here that the monocrystalline alloy (an
FeGa alloy or an FeGaX alloy) constituting the magnetostriction
element of the present embodiment may contain trace amounts of
unavoidable elements (for example, less than 0.005 at % of oxygen),
provided that the monocrystalline alloy is configured essentially
from the elements specified above.
[0040] As used herein, "gradient" means the presence of an increase
or a decrease of a predetermined value, for example, a
concentration, along a direction from one specified location to
another. Specifically, the term "gradient" as used herein means
monotonous decrease or monotonous increase. To be more specific, in
the present disclosure, the Ga concentration gradient is a measured
SPMA value taken end-to-end at the center of the magnetostriction
element, for example, by a spot analysis at different points of the
magnetostriction element, or by a line analysis of the
magnetostriction element.
[0041] In the present disclosure, the <100> crystal
orientation of the monocrystalline alloy can be determined by using
a known method. However, specifically, the <100> crystal
orientation of the monocrystalline alloy is one determined by using
an EBSD (Electron Backscatter Diffraction) technique. The
<100> orientation of the FeGa alloy or FeGaX alloy is not
easily magnetizable. However, the magnetostriction element is able
to produce large magnetostriction because the monocrystalline alloy
in the magnetostriction element of the present embodiment has the
<100> crystal orientation along a direction parallel to the
longitudinal direction of the magnetostriction element. The
magnetostriction element of the present embodiment can also produce
large magnetostriction when the direction parallel to the
longitudinal direction of the magnetostriction element has a small
angle difference of 10.degree. or less, preferably 6.degree. or
less, more preferably 4.degree. or less from the <100>
crystal orientation of the FeGa alloy or FeGaX alloy. Such a
magnetostriction element also represents the magnetostriction
element of the present embodiment.
[0042] The magnetostriction element of the present embodiment is
described below in greater detail, with reference to the
accompanying drawings.
[0043] FIG. 1 is a schematic diagram of a magnetostriction element
of an embodiment of the present disclosure. A magnetostriction
element 1 is formed of a magnetostrictive material that is a
monocrystalline alloy represented by the foregoing formula (1). As
illustrated in FIG. 1, the magnetostriction element 1 is a
plate-shaped element extending along its longitudinal direction
between a first end 1a at one end of the magnetostriction element
and a second end 1b at the opposite end. As illustrated in FIG. 1,
the magnetostriction element has a spot A at the second end 1b side
of the magnetostriction element, a spot B in the middle, and a spot
C at the first end 1a side of the magnetostriction element along
the longitudinal direction between the first end 1a and the second
end 1b of the magnetostriction element. The magnetostriction
element 1 has the <100> crystal orientation of the
monocrystalline alloy of formula (1) along a direction parallel to
the longitudinal direction, and has decreasing Ga concentrations
from spot A to spot B and to spot C when measured at these
points.
[0044] Preferably, the Ga concentration is 14 at % to 16 at % at
the first end 1a of the magnetostriction element, and 17 at % to 19
at % at the second end 1b of the magnetostriction element.
Preferably, the Ga concentration becomes smaller from the second
end 1b of the magnetostriction element toward the first end 1a of
the magnetostriction element at an average rate of 0.15 at % to 0.2
at % per millimeter. The Ga concentration at the first end 1a of
the magnetostriction element and at the second end 1b of the
magnetostriction element may be a concentration at a location near
the edge (or side) of the magnetostriction element 1. For example,
the Ga concentration is a concentration as measured in a region
within 0 to 3 mm, typically about 0.5 to 2.5 mm, from the edge of
the magnetostriction element 1.
[0045] FIG. 2 is a graph schematically representing a distribution
of Ga concentration in the magnetostriction element of the
embodiment of the present disclosure. In FIG. 2, the x axis
represents spots A, B, and C of the magnetostriction element 1, and
the y axis represents the Ga concentration (at %) of the
magnetostriction element 1. For example, as schematically
represented in the distribution graph, the Ga concentration of the
magnetostriction element 1 of the present embodiment has a
concentration gradient, and monotonously decreases from spot A to
spot C (from the second end 1b of the magnetostriction element to
the first end 1a of the magnetostriction element along the
longitudinal direction).
[0046] Because of the Ga concentration gradient, the
magnetostriction element 1 of the embodiment of the present
disclosure shows different magnetic characteristics (magnetic
anisotropy) in the gradient. Specifically, in the magnetostriction
element 1, the extent of magnetic flux density change is different
at different points of the Ga concentration gradient. In the
present disclosure, a magnetic flux density change due to applied
stress can be measured with a B--H curve measurement device
installed in a tensile-compression tester.
[0047] The method used to produce the magnetostriction element 1
according to the present embodiment is not particularly limited,
and any appropriately selected alloy manufacturing method may be
used. Examples of such methods include the Czochralski technique
(CZ technique), the Bridgeman technique, and a rapid solidification
method. With the CZ technique, large crystals can be produced with
accurate chemical compositions and crystal orientations. The Ga
concentration gradient in the magnetostriction element 1 can be
created by a skilled person forming the magnetostriction element 1
using, for example, the CZ technique. For example, the crucible is
rotated in the reversed direction from the direction of rotation of
a seed crystal, and each step is performed under appropriately
adjusted conditions (for example, the rotation speed of the seed
crystal and the crucible, and pressure). The concentration can then
be measured and confirmed by EPMA analysis. The magnetostriction
element 1 can be shaped as desired using any known technique. For
example, the magnetostriction element 1 may be cut out by wire
discharge machining.
Magnetostriction-Type Vibration Powered Generator
[0048] FIG. 3 is a cross sectional view of a magnetostriction-type
vibration powered generator equipped with the magnetostriction
element of the embodiment of the present disclosure. FIG. 4 is a
perspective view of the magnetostriction-type vibration powered
generator equipped with the magnetostriction element of the
embodiment of the present disclosure. As illustrated in FIGS. 3 and
4, a magnetostriction-type vibration powered generator 10 includes
a power generating section 2, and a frame 3 joined to the power
generating section 2.
[0049] The power generating section 2 has a first end 2a and a
second end 2b. The frame 3 has a first end 3a and a second end 3b.
The second end 2b of the power generating section is joined to the
first end 3a of the frame.
[0050] The method used to join the second end 2b of the power
generating section to the first end 3a of the frame is not
particularly limited, as long as it does not seriously impair the
function of the magnetostriction-type vibration powered generator
10 of the present embodiment as a whole, specifically, the function
that forms an appropriate magnetic circuit. For example, these ends
may be fixed to each other using screws, bolts, nuts, solders,
adhesives, or brazing filler metals, particularly, screws, bolts,
or nuts.
[0051] The frame 3 has a frame body 3A and a magnet 4. The frame
body 3A is made of a magnetic material, particularly, a
ferromagnetic material, and extends between the first end 3a and
the second end 3b of the frame. For example, the ferromagnetic
metallic material may be a cold rolled steel plate, or a steel band
(SPCC, SPCD, SPCE, SPCF, SPCG). The frame body 3A shown in FIGS. 3
and 4 has a C-shape. However, the shape is not particularly
limited, as long as the constituent members are joined to one
another, and function as the magnetostriction-type vibration
powered generator 10 after manufacture. For example, the power
generating section 2 and the frame 3, as a whole, may have, for
example, a C- or a U-shape after being joined to each other.
Specifically, the shape is not limited, as long as the power
generating section 2 extending end-to-end between the second end 2b
and the first end 2a is facing the frame body 3A extending toward
the second end 3b of the frame, and the first end 2a (the end on
the diaphragm 5 side, specifically, the free end) of the power
generating section is facing the second end 3b (the fixed end) of
the frame.
[0052] The magnet 4 is provided on the frame body 3A, opposite the
magnetostriction element1 of the power generating section 2.
Preferably, the magnet 4 is provided on the frame body 3A so as to
face the magnetostriction element1 at the first end 1a of the
magnetostriction element 1. Specifically, the magnet 4 may be
provided so as to form an air gap with the magnetostriction element
1. With such an air gap, it is possible to form a desirable closed
magnetic circuit of the magnet 4, the magnetostriction element 1,
and the frame body 3A through the air gap. The magnet 4 is not
particularly limited, as long as it is a substance having the
property to attract a magnetic material, and that generates a
bipolar magnetic field. Examples of such materials include a
neodymium magnet, a samarium-cobalt magnet, and an alnico magnet.
Preferably, the magnet is a neodymium magnet.
[0053] The frame body 3A and the magnet 4 can be installed, for
example, simply by mounting the magnet 4 on the frame body 3A,
which is a magnetic material. With the magnet 4 mounted on the
frame body 3A, the generated magnetic force can hold the magnet 4
in place with the magnetic field lines running through the frame
body 3A. The magnet 4 may be installed or attached using a method
involving other types of magnetic forces. When the frame body 3A
and the magnet 4 are bonded to each other with an adhesive or other
such materials that do not easily pass magnetic field lines, the
resulting magnetic circuit is reduced in size as such materials
become magnetic reluctance.
[0054] As illustrated in FIGS. 3 and 4, the power generating
section 2 includes a diaphragm 5 and a coil 6, in addition to the
magnetostriction element1 of the embodiment described above.
[0055] The diaphragm 5 is disposed at the first end 2a of the power
generating section. The material of the diaphragm 5 is not
particularly limited, as long as it is a non-magnetic material. For
example, the diaphragm 5 is configured from a non-magnetic material
such as a non-magnetic metal (for example, aluminum, titanium,
copper, or brass), and a resin (for example, acrylic resin). By
varying the dimensions (length and thickness) of the diaphragm 5 or
by attaching a weight to the diaphragm, the spring characteristics
of the diaphragm 5 can be altered to adjust the resonant
frequency.
[0056] The magnetostriction element 1 is disposed at the second end
2b of the power generating section. The magnetostriction element 1,
which is the magnetostriction element 1 of the embodiment described
above, is disposed in such an orientation that the direction from
the second end 2b to the first end 2a of the power generating
section corresponds to the longitudinal direction of the
magnetostriction element1, and that the magnetostriction element
joins the diaphragm 5 at the first end 1a, that is, the end with a
lower Ga concentration (in the vicinity of spot C).
[0057] In the magnetostriction element 1, the Ga concentration is
higher at spot A, and the magnetic flux density difference under no
load and under applied stress is large at spot A when the applied
stress is large. At spot C, where the Ga concentration is lower,
the magnetic flux density difference under no load and under
applied stress is large when the applied stress is small.
Accordingly, the magnetostriction element 1, which is made of an
FeGa alloy or an FeGx alloy, can effectively produce a large
magnetic flux density change as a whole when the magnetostriction
element 1 has its second end 1b, near spot A, disposed on the frame
side of the magnetostriction element (fixed-end side) and its first
end 1a, near spot C, disposed on the diaphragm 5 side (free-end
side). This is because the configuration of the
magnetostriction-type vibration powered generator 10 is such that
the magnetostriction element 1 experiences a greater stress at the
fixed end than at the free end. In this way, the
magnetostriction-type vibration powered generator 10 can have
increased power density. In the present disclosure, a magnetic flux
density difference under no load and under applied stress means a
magnetic flux density difference between the magnetic flux density
measured under no load with a B--H curve measurement device, and
the magnetic flux density measured under applied tensile or
compressional stress with a B--H curve measurement device installed
in a tensile-compression tester.
[0058] The method used to attach (or join) the diaphragm 5 to the
magnetostriction element 1 is not particularly limited. For
example, these may be fixed to each other using, for example,
screws, bolts, nuts, solders, adhesives, brazing filler metals, or
double-sided tapes. Preferably, the diaphragm 5 and the
magnetostriction element 1 are fixed to each other with screws,
bolts, nuts, or the like.
[0059] The coil 6 is wrapped around the magnetostriction element 1
along the longitudinal direction of extension of the
magnetostriction element1, that is, in a direction from the second
end 2b to the first end 2a of the power generating section. The
coil 6 generates a voltage that is proportional to the
time-dependent changes occurring in the magnetic field lines
running through the magnetostriction element 1, in accordance with
the law of electromagnetic induction. The material of the coil 6 is
not particularly limited. For example, a copper wire may be used. A
generated voltage can be determined by V=Nd.PHI./dt, where N is the
number of turns in the coil 6, and .PHI. is the magnetic flux.
Accordingly, a large voltage can be generated by increasing the
amount of magnetic flux change per unit time, or by increasing the
number of turns in the coil 6. The amount of magnetic flux change
per unit time is determined by the resonant frequency or other
mechanical characteristics of the power-generating element.
Accordingly, an easier way of increasing the generated voltage of
the power-generating element is to increase the number of turns in
the coil 6.
EXAMPLES
[0060] The present disclosure is described below in greater detail
by way of Examples and Comparative Examples. The present
disclosure, however, is not limited by the following
descriptions.
Example 1
[0061] In Example 1, a plate-shaped FeGa-alloy magnetostriction
element was produced that had varying Ga concentrations along its
longitudinal direction. The magnetostriction element was then
measured for magnetic flux density under no applied stress and
under applied compressional stress, and changes occurring in
magnetic flux density were confirmed.
Production of Magnetostriction Element
[0062] In order to produce an FeGa-alloy magnetostriction element
of
[0063] Example 1-1, iron (purity 99.999%) and gallium (purity
99.999%) were weighed with an electronic balance. The content of
each element in alloy specimens was measured and adjusted by EPMA
analysis.
[0064] Specimens were grown using a high-frequency dielectric
heating CZ furnace. A dense alumina crucible measuring 45 mm in
outer diameter (.PHI.) was disposed inside a graphite crucible
having an inner diameter .PHI. of 50 mm, and weighed 400 g of Fe
and Ga was supplied as raw materials of each alloy specimen. The
crucibles charged with the raw materials were placed in a growth
furnace, and an argon gas was introduced after creating a vacuum
inside the furnace. Heat was applied as soon as the pressure inside
the furnace became atmospheric pressure, and the alloy was heated
for 12 hours, until a melt was obtained. An FeGa monocrystal was
cut to produce a seed crystal of <100> orientation, and the
seed crystal was lowered down to the vicinity of the melt. While
being rotated at 5 ppm, the seed crystal was then gradually lowered
toward the melt until the tip of the seed crystal contacted the
melt. In order to create a Ga concentration gradient in the
specimen, the crucible was rotated at 10 rpm in the opposite
direction from the seed crystal, and the crystal was grown by
gradually decreasing temperature, before lifting the seed crystal
at a rate of 1.0 mm/hr. This produced a monocrystalline alloy
having a Ga concentration gradient and measuring 10 mm in diameter
and 80 mm in length along the length of its body. For measurement,
the monocrystalline alloy was cut into a plate-shaped
magnetostriction element by wire discharge machining. Here, the
plate-shaped magnetostriction element had cross sectional
dimensions measuring 10 mm in width, 1 mm in height, and 20 mm in
length (a longitudinal distance between the first end and the
second end). The longitudinal direction was parallel to the
<100> orientation of the FeGa alloy. This produced the
FeGa-alloy magnetostriction element of Example 1-1 of the shape
shown in FIG. 1 having varying Ga concentrations along the
longitudinal direction.
[0065] In order to produce an FeGa-alloy magnetostriction element
of Comparative Example 1-1, an FeGa monocrystalline alloy was
produced using the Bridgeman technique, which enables growth of
monocrystals of a uniform composition. As in Example 1-1, the
monocrystalline alloy was cut by wire discharge machining into a
plate shape measuring 10 mm.times.1 mm in cross section and 20 mm
in length (a longitudinal distance between the first end and the
second end). Here, the longitudinal direction was parallel to the
<100> orientation of the FeGa alloy, as in Example 1-1.
Ga Concentration Measurement of Magnetostriction Elements
[0066] The Ga concentrations of the magnetostriction elements
of
[0067] Example 1-1 and Comparative Example 1-1 were measured by
EPMA analysis. Specifically, the Ga concentrations of the FeGa
monocrystalline alloys were measured at spots A, B, and C shown in
FIG. 1.
Magnetic Flux Density Measurement of Magnetostriction Element under
No Applied Stress and under Applied Compressional Stress
[0068] The magnetostriction elements of Example 1-1 and Comparative
Example 1-1 were measured for magnetic flux density under no
applied stress and under applied stress (under 5 MPa compressional
stress and under 15 MPa compressional stress) at 8 kA/m.
Specifically, the magnetic flux density was measured for a length
of about 2 mm in the vicinity of spots A, B, and C shown in FIG. 1.
This was accomplished by using a B--H measurement device with a
short-length detection coil.
[0069] Table 1 shows the results of the Ga concentration (at %; the
rest is the Fe concentration (at %)) measurements at spots A, B,
and C, and the results of the magnetic flux density (T)
measurements for the FeGa-alloy magnetostriction elements of
Example 1-1 and Comparative Example 1-1 conducted under no applied
stress and under applied compressional stress.
TABLE-US-00001 TABLE 1 Ex. 1-1 Com. Ex. 1-1 Ga concentration at
spot A [at. %] 18.4 18.4 Ga concentration at spot B [at. %] 16.9
18.4 Ga concentration at spot C [at. %] 15.4 18.4 Magnetic flux
density [T] Near spot A 1.6 1.6 under no load Near spot B 1.2 1.6
Near spot C 0.8 1.6 Magnetic flux density [T] Near spot A 1.5 1.5
under 5 MPa compression Near spot B 1.0 1.5 Near spot C 0.5 1.5
Magnetic flux density [T] Near spot A 0.8 0.6 under 15 MPa
compression Near spot B 0.7 0.6 Near spot C 0.6 0.6
[0070] As shown in Table 1, the Ga concentration was 1.5 at % lower
at spot B, and 3 at % lower at spot C than at spot A in Example
1-1. That is, because the magnetostriction element was 20-mm long,
the magnetostriction element of Example 1-1 had a composition
gradient in which the Ga concentration monotonously decreased at
0.15 at %/mm. In Comparative Example 1-1, the Ga concentration was
18.4 at % in all of spot A, B, and C, and the composition was
uniform.
[0071] In Example 1-1, the magnetic flux density monotonously
decreased with the measured value of 1.6 T at spot A, 1.2 T at spot
B, and 0.8 T at spot C under no applied stress. This result is
considered to be due to the decreasing Ga concentrations from spot
A to spot C in the FeGa-alloy magnetostriction element of Example
1-1. That is, there appears to be a correlation between Ga
concentration and magnetic flux density. The same correlation also
should be present under applied compressional stress. Under an
applied compressional stress of 5 MPa, the magnetic flux density
showed a decrease from 1.5 T at spot A to 1.0 T at spot B, and to
0.5 T at spot C. Similarly, under an applied compressional stress
of 15 MPa, the magnetic flux density showed a decrease from 0.8 T
at spot A to 0.7 T at spot B, and to 0.6 T at spot C. These results
also suggest that there is a correlation between Ga concentration
and magnetic flux density.
[0072] In Comparative Example 1-1, the Ga concentration was
uniform, with spots A, B, and C all showing a Ga concentration of
18.4 at %. Here, the magnetic flux density was 1.6 T under no
applied stress, and 1.5 T and 0.6 T under applied compressional
stress (under 5 MPa and under 15 MPa), regardless of the spot, A,
B, or C. It can be said from these results that there is a
correlation between Ga concentration and magnetic flux density.
[0073] The results for Example 1-1 and Comparative Example 1-1
showed that there is a correlation between Ga concentration and
magnetic flux density in the magnetostriction elements formed of
FeGa-alloy magnetostrictive material, and that, with the Ga
concentration gradient in the composition of the magnetostriction
element, the magnetic flux density also has a gradient, under no
applied stress and under applied compressional stress. In both
Example 1-1 and Comparative Example 1-1, the magnetic flux density
was smaller under applied compressional stress than under no
applied stress. This is probably a result of the hindered motion of
the domain wall inside the magnetostriction element due to the
applied compressional stress to the magnetostriction element formed
of magnetostrictive material.
Example 2
[0074] In Example 2, magnetostriction elements of various Ga
concentrations were produced in the same manner as for the
FeGa-alloy magnetostriction element of Example 1-1. These were then
measured for magnetic flux density under no applied stress and
under applied compressional stress, and changes occurring in
magnetic flux density were confirmed. For the evaluation of the
power density of each magnetostriction element, the
magnetostriction element was installed in a magnetostriction-type
vibration powered generator of the configuration shown in FIGS. 3
and 4, and measured for power density.
[0075] The magnetostriction elements used for measurement had a
plate shape as in Example 1-1. The Ga concentrations in the
magnetostriction elements had the values shown in Table 2 at spots
A, B, and C as measured by EPMA analysis (the rest is the Fe
concentration (at %)). In Examples 2-1 to 2-4, the magnetostriction
elements had varying Ga concentrations at spots A, B, and C. The
magnetostriction elements of Comparative Examples 2-1 and 2-3 had a
constant Ga concentration. The magnetostriction element of
Comparative Example 2-2 had the same Ga concentrations at spots A,
B, and C as Example 2-1. The magnetostriction elements were
produced and cut (wire discharge machining) in the same manner as
in Example 1-1. The magnetostriction elements were measured for
magnetic flux density under no applied stress and applied
compressional stress in the same manner as in Example 1-1.
Evaluation of Power Density in Magnetostriction-Type Vibration
Powered Generator Equipped with Magnetostriction Element
[0076] The magnetostriction elements produced in the manner
described above were each installed in a magnetostriction-type
vibration powered generator of the configuration shown in FIGS. 3
and 4. In Examples 2-1 to 2-4 and Comparative Examples 2-1 and 2-3,
the magnetostriction element was installed in such an orientation
that spot C was on the diaphragm side (free-end side), and spot A
was on the frame side (fixed-end side). The orientation was
reversed in Comparative Example 2-2. The magnetostriction-type
vibration powered generator equipped with the magnetostriction
element was fitted to a vibrator, and the power density was
measured. Specifically, vibration was applied from the vibrator at
an acceleration of 2 G. The generated voltage was detected with an
oscilloscope, and the resonant-frequency power output was
calculated. The power density was then determined by dividing the
calculated value by the size of the magnetostriction-type vibration
powered generator.
[0077] As mentioned above, a magnetostriction-type vibration
powered generator applied to a tire air pressure monitoring system
or a sensor network for factories requires a consumed power density
of at least about 1.0 mW/cm.sup.3. By using this as a reference,
the power density was determined as being acceptable when the
calculated value was 1.0 mW/cm.sup.3 or more, and unacceptable when
the calculated value was less than 1.0 mW/cm.sup.3.
[0078] Table 2 shows the measurement results for Examples 2-1 to
2-4 and Comparative Examples 2-1 to 2-3, specifically, the Ga
concentrations at spots A, B, and C of the FeGa-alloy
magnetostriction element, the magnetic flux density under no
applied stress and under applied compressional stress, the magnetic
flux density difference under no applied stress and under applied
compressional stress, the installation direction of the
magnetostriction element in the magnetostriction-type vibration
powered generator, and the power density values, along with the
evaluation results.
TABLE-US-00002 TABLE 2 Ex. 2-1 Ex. 2-2 Ex. 2-3 Ex. 2-4
Magnetostriction Ga concentration at spot A [at. %] 19 19 18 17
element Ga concentration at spot B [at. %] 17.5 17 16.5 15.5 Ga
concentration at spot C [at. %] 16 15 15 14 Magnetic flux density
Near spot A 1.65 1.65 1.55 1.2 [T] under no load Near spot B 1.2
1.25 1.15 0.8 Near spot C 0.75 0.85 0.75 0.4 Magnetic flux density
Near spot A 1.6 1.6 1.4 1.1 [T] under 5 MPa Near spot B 1.1 1 0.9
0.6 compression Near spot C 0.4 0.45 0.45 0.1 Magnetic flux density
Near spot A 0.85 0.85 0.8 0.7 [T] under 15 MPa Near spot B 0.75 0.7
0.65 0.6 compression Near spot C 0.6 0.55 0.55 0.4 Magnetic flux
density Near spot A 0.05 0.05 0.15 0.1 difference [T] Near spot B
0.1 0.25 0.25 0.2 under no load and Near spot C 0.35 0.4 0.3 0.3
under applied 5 MPa compression Magnetic flux density Near spot A
0.8 0.8 0.75 0.5 difference [T] under Near spot B 0.45 0.55 0.5 0.2
no load and under Near spot C 0.15 0.3 0.2 0 applied 15 MPa
compression Magnetostriction- Frame side (fixed-end side) Spot A
Spot A Spot A Spot A type vibration Diaphragm side (free-end side)
Spot C Spot C Spot C Spot C powered generator Power density
[mW/cm.sup.3] 2.1 1.9 1.8 1.6 Evaluation result Acceptable
Acceptable Acceptable Acceptable Com. Ex. 2-1 Com. Ex. 2-2 Com. Ex.
2-3 Magnetostriction Ga concentration at spot A [at. %] 19 19 17
element Ga concentration at spot B [at. %] 19 17.5 17 Ga
concentration at spot C [at. %] 19 16 17 Magnetic flux Near spot A
1.65 1.65 1.25 density [T] under Near spot B 1.65 1.2 1.25 no load
Near spot C 1.65 0.75 1.25 Magnetic flux Near spot A 1.6 1.6 1
density [T] under 5 Near spot B 1.6 1.1 1 MPa compression Near spot
C 1.6 0.4 1 Magnetic flux Near spot A 0.85 0.85 0.7 density [T]
under Near spot B 0.85 0.75 0.7 15 MPa Near spot C 0.85 0.6 0.7
compression Magnetic flux Near spot A 0.05 0.05 0.25 density
difference Near spot B 0.05 0.1 0.25 [T] under no load Near spot C
0.05 0.35 0.25 and under applied 5 MPa compression Magnetic flux
Near spot A 0.8 0.8 0.55 density difference Near spot B 0.8 0.45
0.55 [T] under no load Near spot C 0.8 0.15 0.55 and under applied
15 MPa compression Magnetostriction- Frame side (fixed-end side)
Spot A Spot C Spot A type vibration Diaphragm side (free-end side)
Spot C Spot A Spot C powered generator Power density [mW/cm.sup.3]
0.7 0.5 0.4 Evaluation result Unacceptable Unacceptable
Unacceptable
[0079] As shown in Table 2, the power density was 1.0 mW/cm.sup.3
or more, and the values were acceptable in all of Examples 2-1 to
2-4.
[0080] In Example 2-1, the Ga concentration monotonously decreased
with the measured value of 19 at % at spot A, 17.5 at % at spot B,
and 16 at % at spot C. The magnetic flux density under no applied
stress also decreased with the measured value of 1.65 T at spot A,
1.2 T at spot B, and 0.75 T at spot C. Under applied compressional
stress (5 MPa), the magnetic flux density showed a decrease from
1.6 T at spot A to 1.1 T at spot B, and to 0.4 T at spot C. Under
applied compressional stress (15 MPa), the magnetic flux density
showed a decrease from 0.85 T at spot A to 0.75 T at spot B, and to
0.6 T at spot C. These results also suggest that there is a
correlation between Ga concentration and magnetic flux density, as
in Example 1-1. By focusing on the magnetic flux density difference
under no applied stress and under applied compressional stress in
Example 2-1, the largest magnetic flux density difference under no
applied stress and under an applied compressional stress of 5 MPa
was 0.35 T, and this occurred at spot C. Under no applied stress
and under an applied compressional stress of 15 MPa, the largest
magnetic flux density difference was 0.8 T, and this occurred at
spot A.
[0081] In Example 2-1, the magnetostriction element was installed
in the magnetostriction-type vibration powered generator in such an
orientation that spot A, where the magnetic flux density difference
under no applied stress and under an applied compressional stress
of 15 MPa (under a large applied stress) was the greatest and the
Ga concentration was the highest, was on the frame side (fixed-end
side), and spot C, where the magnetic flux density difference under
no applied stress and under an applied compressional stress of 5
MPa (under a small applied stress) was the greatest and the Ga
concentration was the lowest, was on the diaphragm side (free-end
side). This is probably the reason for the increased magnetic flux
density change in the FeGa-alloy magnetostriction element as a
whole, and the large power density of 1.0 mW/cm.sup.3 or more.
[0082] The same pattern was observed in Examples 2-2 to 2-4. In
Example 2-2, the largest magnetic flux density difference under no
applied stress and under an applied compressional stress of 5 MPa
was 0.4 T, and this occurred at spot C. Under no applied stress and
under an applied compressional stress of 15 MPa, the largest
magnetic flux density difference was 0.8 T, and this occurred at
spot A. In Example 2-3, the largest magnetic flux density
difference under no applied stress and under an applied
compressional stress of 5 MPa was 0.3 T, and this occurred at spot
C. Under no applied stress and under an applied compressional
stress of 15 MPa, the largest magnetic flux density difference was
0.75 T, and this occurred at spot A. In Example 2-4, the largest
magnetic flux density difference under no applied stress and under
an applied compressional stress of 5 MPa was 0.3 T, and this
occurred at spot C. Under no applied stress and under an applied
compressional stress of 15 MPa, the largest magnetic flux density
difference was 0.55 T, and this occurred at spot A. As in Example
2-1, the magnetostriction element was installed in the
magnetostriction-type vibration powered generator in such an
orientation that spot A, where the magnetic flux density difference
under no applied stress and under an applied compressional stress
of 15 MPa (under a large applied stress) was the greatest and the
Ga concentration was the highest, was on the frame side (fixed-end
side), and spot C, where the magnetic flux density difference under
no applied stress and under an applied compressional stress of 5
MPa (under a small applied stress) was the greatest and the Ga
concentration was the lowest, was on the diaphragm side (free-end
side). This is probably the reason for the increased magnetic flux
density change in the FeGa-alloy magnetostriction element as a
whole, and the large power density of 1.0 mW/cm.sup.3 or more.
[0083] As shown in Table 2, the power density was less than 1.0
mW/cm.sup.3, and the values were unacceptable in Comparative
Examples 2-1 and 2-3 in which the magnetostriction elements of
uniform Ga concentration were installed. The smaller power density
values are probably due to the smaller magnetic flux density
changes occurring in the magnetostriction element as a whole as a
result of the stress being distributed over the frame side
(fixed-end side) and the diaphragm side (free-end side) of the
magnetostriction element in the magnetostriction-type vibration
powered generator, and thus creating a distribution in the magnetic
field lines running through the magnetostriction element formed of
magnetostrictive material. In Comparative Example 2-2, the
magnetostriction element was installed in the magnetostriction-type
vibration powered generator in such an orientation that spot A,
where the magnetic flux density difference under no applied stress
and under an applied compressional stress of 15 MPa (under a large
applied stress) was the greatest and the Ga concentration was the
highest, was on the diaphragm side (free-end side), and spot C,
where the magnetic flux density difference under no applied stress
and under an applied compressional stress of 5 MPa (under a small
applied stress) was the greatest and the Ga concentration was the
highest, was on the frame side (fixed-end side). This is probably
the reason for the decreased magnetic flux density change in the
FeGa-alloy magnetostriction element as a whole, and the small power
density of less than 1.0 mW/cm.sup.3. That is, the smaller power
density is considered to be due to the smaller magnetic flux
density change occurring in the magnetostriction element in the
magnetostriction-type vibration powered generator as a whole.
Example 3
[0084] In Example 3, the Ga concentration of the FeGa alloy of
Example 1-1 was varied, and a trace amount of Sm, Cu, or C was
added to produce magnetostriction elements. For the evaluation of
the power density of the magnetostriction element, the
magnetostriction element was installed in the magnetostriction-type
vibration powered generator in the same manner as in Example 2, and
the power density was measured to confirm the effectiveness of
adding these additional elements.
Evaluation of Power Density in Magnetostriction-Type Vibration
Powered Generator Equipped with Magnetostriction Element
[0085] The magnetostriction elements used for measurement had a
plate shape as in Example 1-1. The Ga concentrations (at %) at
spots A, B, and C of the magnetostriction elements had the values
shown in Tables 3-1 and 3-2 (spot A: 19; spot B: 17.5; spot C: 16)
and in Tables 4-1 and 4-2 (spot A: 17; spot B: 15.5; spot C: 14) as
measured by EPMA analysis. Tables 3-1 and 3-2 and Tables 4-1 and
4-2 also show the type of the additional element, Sm, Cu, or C,
added to the magnetostriction elements of Examples 3-1 to 3-12,
along with the concentrations (at %) of these elements. The
additional element, Sm, Cu, or C, was also added in Comparative
Examples 3-1 to 3-14. However, in Comparative Examples 3-1, 3-2,
3-4 to 3-9, and 3-11 to 3-14, these were added in different amounts
from the amounts added in Examples. In Comparative Examples 3-3 and
3-10, the magnetostriction element was installed in the
magnetostriction-type vibration powered generator in the reversed
direction from the other Comparative Examples.
[0086] The magnetostriction elements were produced and cut (wire
discharge machining) in the same manner as in Example 1-1. However,
the additional element, Sm, Cu, or C, was supplied as a raw
material to the crucible in the first step after weighing these
elements with Fe and Ga (both have 99.99% purity) in the first
step. The Sm, Cu, or C content was measured and adjusted by SPMA
analysis, as was the case for Fe and Ga. The magnetostriction
elements had no concentration gradient for Sm, Cu, and C, even
though the magnetostriction elements were produced in the same
manner as in Example 1-1. This is probably due to the much lower
melting point of gallium compared to the other elements, causing
gallium to preferentially vaporize. Another possibility is only the
trace amount of Sm, Cu, or C added. The power density of the
magnetostriction element in the magnetostriction-type vibration
powered generator was measured and evaluated in the same manner as
in Example 2.
[0087] Tables 3-1 and 3-2 and Tables 4-1 and 4-2 show the
measurement results for Examples 3-1 to 3-6 and Comparative
Examples 3-1 to 3-7 and for Examples 3-7 to 3-12 and Comparative
Examples 3-8 to 3-14, specifically, the Ga concentrations at spots
A, B, and C of the magnetostriction element, the type and
concentration of the additional element, the installation direction
of the magnetostriction element in the magnetostriction-type
vibration powered generator, and the measured power density values,
along with the evaluation results.
TABLE-US-00003 TABLE 3-1 Ex. 3-1 Ex. 3-2 Ex. 3-3 Ex. 3-4 Ex. 3-5
Ex. 3-6 Magnetostriction Ga concentration at 19 19 19 19 19 19
element spot A [at. %] Ga concentration at 17.5 17.5 17.5 17.5 17.5
17.5 spot B [at. %] Ga concentration at 16 16 16 16 16 16 spot C
[at. %] Concentration Sm 1.0 0 0 0 0.5 0 of additional Cu 0 0.5 0 0
0 1.0 element [at. %] C 0 0 1.0 0.5 0 0 Vibration Frame side (fixed
end) Spot A Spot A Spot A Spot A Spot A Spot A powered Diaphragm
side (free Spot C Spot C Spot C Spot C Spot C Spot C generator end)
Power density [mW/cm.sup.3] 2.3 2.2 2.2 2.2 2.3 2.4 Evaluation
result Acceptable Acceptable Acceptable Acceptable Acceptable
Acceptable
TABLE-US-00004 TABLE 3-2 Com. Ex. Com. Ex. Com. Ex. Com. Ex. Com.
Ex. Com. Ex. Com. Ex. 3-1 3-2 3-3 3-4 3-5 3-6 3-7 Magnetostriction
Ga concentration at 19 19 19 19 19 19231 19 element spot A [at. %]
Ga concentration at 17.5 17.5 17.5 17.5 17.5 17.5 17.5 spot B [at.
%] Ga concentration at 16 16 16 16 16 16 16 spot C [at. %]
Concentration of Sm 1.1 0.4 1.0 0 0 0 0 additional Cu 0 0 0 1.1 0.4
0 0 element [at. %] C 0 0 0 0 0 1.1 0.4 Vibration Frame side (fixed
end) Spot A Spot A Spot C Spot A Spot A Spot A Spot A powered
Diaphragm side Spot C Spot C Spot A Spot C Spot C Spot C Spot C
generator (free end) Power density [mW/cm.sup.3] 0.8 0.9 0.7 0.5
0.7 0.9 0.8 Evaluation result Unaccept- Unaccept- Unaccept-
Unaccept- Unaccept- Unaccept- Unaccept- able able able able able
able able
TABLE-US-00005 TABLE 4-1 Ex. 3-7 Ex. 3-8 Ex. 3-9 Ex. 3-10 Ex. 3-11
Ex. 3-12 Magnetostriction Ga concentration at 17 17 17 17 17 17
element spot A [at. %] Ga concentration at 15.5 15.5 15.5 15.5 15.5
15.5 spot B [at. %] Ga concentration at 14 14 14 14 14 14 spot C
[at. %] Concentration Sm 1.0 0 0 0 0.5 0 of additional Cu 0 0.5 0 0
0 1.0 element [at. %] C 0 0 1.0 0.5 0 0 Vibration Frame side (fixed
end) Spot A Spot A Spot A Spot A Spot A Spot A powered Diaphragm
side (free Spot C Spot C Spot C Spot C Spot C Spot C generator end)
Power density [mW/cm.sup.3] 1.7 1.8 1.8 1.9 1.7 1.6 Evaluation
result Acceptable Acceptable Acceptable Acceptable Acceptable
Acceptable
TABLE-US-00006 TABLE 4-2 Com. Ex. Com. Ex. Com. Ex. Com. Ex. Com.
Ex. Com. Ex. Com. Ex. 3-8 3-9 3-10 3-11 3-12 3-13 3-14
Magnetostriction Ga concentration at 17 17 17 17 17 17 17 element
spot A [at. %] Ga concentration at 15.5 15.5 15.5 15.5 15.5 15.5
15.5 spot B [at. %] Ga concentration at 14 14 14 14 14 14 14 spot C
[at. %] Concentration of Sm 1.1 0.4 1.0 0 0 0 0 additional Cu 0 0 0
1.1 0.4 0 0 element [at. %] C 0 0 0 0 0 1.1 0.4 Vibration Frame
side (fixed end) Spot A Spot A Spot C Spot A Spot A Spot A Spot A
powered Diaphragm side Spot C Spot C Spot A Spot C Spot C Spot C
Spot C generator (free end) Power density [mW/cm.sup.3] 0.5 0.7 0.6
0.4 0.6 0.5 0.4 Evaluation result Unaccept- Unaccept- Unaccept-
Unaccept- Unaccept- Unaccept- Unaccept- able able able able able
able able
[0088] As shown in Tables 3-1 and 4-1, the power density was 1.0
mW/cm.sup.3 or more, and the values were acceptable in Examples
3-1, 3-2, 3-7, and 3-8 in which trace amounts of Sm were added.
This is probably due to the increased magnetic flux density change
as a result of improved saturation flux density created by (i) the
localized strain induced by addition of Sm having a larger atomic
radius than Fe and Ga, and (ii) the magnetic anisotropy produced in
the crystals by the quadruple moment of the 4f electron of
samarium.
[0089] Comparative Examples 3-1 and 3-8, in which samarium was
added in an amount of 1.1 at %, had power densities of 0.8
mW/cm.sup.3 and 0.5 mW/cm.sup.3, respectively, and the values were
unacceptable, as shown in Tables 3-2 and 4-2. These small power
density values are probably due to the samarium being added beyond
the solid solubility limit, and the emergence of the second phase
inhibiting the movement of the domain wall and reducing the
magnetic flux density change.
[0090] Comparative Examples 3-2 and 3-9, in which samarium was
added in an amount of 0.4 at %, had power densities of 0.9
mW/cm.sup.3 and 0.7 mW/cm.sup.3, respectively, and the values were
unacceptable, as shown in Tables 3-2 and 4-2. This is probably
because the samarium content was too small to sufficiently improve
the saturation flux density.
[0091] It can be said from these results that the Sm concentration
(at %) must fall in a range of 0.5 Sm 1.0 to achieve a power
density of 1.0 mW/cm.sup.3 or more.
[0092] As shown in Tables 3-2 and 4-2, the power density was 0.7
mW/cm.sup.3 in Comparative Example 3-3, and 0.6 mW/cm.sup.3 in
Comparative Example 3-10, and the values were unacceptable in these
comparative examples in which samarium was added, and in which the
magnetostriction element was installed in such an orientation that
spot C of lower Ga concentration was on the frame side, and spot A
of higher Ga concentration was on the diaphragm side. These small
power density values are probably due to the smaller magnetic flux
density change occurring in the magnetostriction element as a whole
as a result of the reduced magnetic flux density difference under
no applied stress and under applied compressional stress due to the
installation direction of the magnetostriction element, as in
Example 2.
[0093] As shown in Tables 3-1 and 4-1, the power density was 1.0
mW/cm.sup.3 or more, and the values were acceptable in Examples
3-3, 3-4, 3-9, and 3-10 in which trace amounts of copper were
added. This is probably a result of the addition of copper
increasing the magnetic anisotropic energy of the crystals in the
alloy.
[0094] As shown in Tables 3-2 and 4-2, the power density was 0.5
mW/cm.sup.3 in Comparative Example 3-4, and 0.4 mW/cm.sup.3 in
Comparative Example 3-11, and the values were unacceptable in these
comparative examples in which Cu was added in an amount of 1.1 at
%. These small power density values are probably due to the copper
being added beyond the solid solubility limit, and the
precipitation of the FeCu-base compound inhibiting the movement of
the domain wall and reducing the magnetic flux density change.
[0095] As shown in Tables 3-2 and 4-2, the power density was 0.7
mW/cm.sup.3 in Comparative Example 3-5, and 0.6 mW/cm.sup.3 in
Comparative Example 3-12, and the values were unacceptable in these
comparative examples in which Cu was added in an amount of 0.4 at
%. This is probably because the copper content was too small to
sufficiently improve the saturation flux density.
[0096] It can be said from these results that the Cu concentration
(at %) must fall in a range of 0.5 Cu 1.0 to achieve a power
density of 1.0 mW/cm.sup.3 or more.
[0097] As shown in Tables 3-1 and 4-1, the power density was 1.0
mW/cm.sup.3 or more, and the values were acceptable in Examples
3-5, 3-6, 3-11, and 3-12 in which trace amounts of carbon were
added. This is probably a result of the addition of carbon inducing
tetragonal crystal strain in the Fe lattice.
[0098] As shown in Tables 3-2 and 4-2, the power density was 0.9
mW/cm.sup.3 in Comparative Example 3-6, and 0.5 mW/cm.sup.3 in
Comparative Example 3-13, and the values were unacceptable in these
comparative examples in which C was added in an amount of 1.1 at %.
These small power density values are probably due to the higher
content of carbon than gallium preventing entry of carbon atoms
into the Fe lattice and reducing the saturation flux density and
the magnetic flux density change.
[0099] As shown in Tables 3-2 and 4-2, the power density was 0.8
mW/cm.sup.3 in Comparative Example 3-7, and 0.4 mW/cm.sup.3 in
Comparative Example 3-14, and the values were unacceptable in these
comparative examples in which C was added in an amount of 0.4 at %.
This is probably because the carbon content was too small to
sufficiently induce tetragonal crystal strain in the Fe
lattice.
[0100] It can be said from these results that the C concentration
(at %) must fall in a range of 0.5.ltoreq.C.ltoreq.1.0 to achieve a
power density of 1.0 mW/cm.sup.3 or more.
[0101] The results of the power density measurement in the
magnetostriction-type vibration powered generator equipped with the
magnetostriction element prepared by adding one of Sm, Cu, and C to
the FeGa alloy confirmed that addition of these additional elements
produces a desirable effect, specifically, a power density of 1.0
mW/cm.sup.3 or more, when 0.5.ltoreq..beta..ltoreq.1.0 is satisfied
in the formula (1) represented by Fe.sub.(100-.alpha.-.beta.)
Ga.sub..alpha.X.sub..beta., where .alpha. and .beta. are the Ga
content (at %) and the X content (at %), respectively.
[0102] Because samarium is a rare earth, the same effect should be
obtained with the rare earths Eu, Gd, Tb, and Dy.
[0103] A magnetostriction element of the present disclosure shows
large magnetostriction, and a magnetostriction-type vibration
powered generator using the magnetostriction element has high power
density. This makes it possible to provide, for example, a
magnetostriction-type sensor or a magnetostriction-type actuator
that could open the door to more effective IoT.
* * * * *