JP2005243929

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DESCRIPTION JP2005243929
PROBLEM TO BE SOLVED: To make uniform the magnetic bias in the giant magnetostrictive
element and reduce the output distortion of the giant magnetostrictive unit. SOLUTION: A giant
magnetostrictive element 11, a coil 12 disposed in the radial direction of the giant
magnetostrictive element 11, and a permanent magnet 14 disposed in the radial direction of the
coil 12 are provided. Assuming that the axial length of the permanent magnet 14 is a1 and the
central diameter of the permanent magnet 14 is b1, in the present invention, 0.3 ≦ b1 / a1 ≦
0.7 is satisfied, and the giant magnetostrictive element 11 is When a length in the axial direction
of is set to a2, 1 ≦ a1 / a2 ≦ 2 is satisfied. As a result, since a uniform magnetic bias can be
applied to the giant magnetostrictive element 11, the output distortion of the giant
magnetostrictive unit 10 can be effectively reduced. [Selected figure] Figure 1
Super magnetostrictive unit
[0001]
The present invention relates to a giant magnetostrictive unit such as an actuator or pressure
sensor using a giant magnetostrictive element.
[0002]
Although magnetostrictive elements that expand and contract in response to the application of a
magnetic field have been known for a long time, the magnetostrictive elements so far have small
displacements, and thus have hardly been used practically.
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However, in recent years, magnetostrictive elements (super-magnetostrictive elements) having a
very large displacement such as 1500 ppm to 2000 ppm have become known, and various usage
forms thereof are currently proposed. For example, focusing on the level of responsiveness and
magnitude of the driving force possessed by the giant magnetostrictive element, it is proposed to
use it as an actuator (see Patent Documents 1 and 2), and to use it as a pressure sensor (patent
document) 3 to 6) are made a lot.
[0003]
Such a giant magnetostrictive unit basically includes a giant magnetostrictive element and a coil
disposed in the radial direction. Therefore, if the giant magnetostrictive element is displaced by
supplying a predetermined current to the coil, this can be used as an actuator. Conversely, if
displacement of the giant magnetostrictive element due to external force is detected as a change
in coil current It becomes possible to use this as a pressure sensor. Patent Document 1: Japanese
Patent Application Laid-Open No. 10-145892 Patent Document 2: Japanese Patent Application
Publication No. 2523027 Patent Document 5 Japanese Patent Application Publication No. 754282 Patent Document 2: Japanese Patent Application Publication No. 11-139270
[0004]
Since the displacement of the giant magnetostrictive element is not directional with respect to
the direction of the magnetic field, depending on the application, it is necessary to apply a
magnetic bias to the giant magnetostrictive element using a permanent magnet. However, the
giant magnetostrictive material generally has a low permeability (.mu. = 6 to about 10), which
causes the problem that the magnetic bias in the giant magnetostrictive element tends to be
uneven depending on the design of the magnetic circuit. If the magnetic bias in the giant
magnetostrictive element is nonuniform, distortion occurs in the output of the giant
magnetostrictive unit. Therefore, it is desirable that the magnetic bias in the giant
magnetostrictive element be as uniform as possible.
[0005]
Therefore, an object of the present invention is to make the magnetic bias in the giant
magnetostrictive element more uniform, thereby reducing the output distortion of the giant
magnetostrictive unit.
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[0006]
The giant magnetostrictive unit according to the present invention comprises a giant
magnetostrictive element, a coil disposed in the radial direction of the giant magnetostrictive
element, and a permanent magnet disposed in the radial direction of the coil, and the length of
the permanent magnet in the axial direction Assuming that the length is a1 and the central
diameter of the permanent magnet is b1, 0.3 ≦ b1 / a1 ≦ 0.7 and the axial length of the super
magnetostrictive element is a2. It is characterized in that 1 ≦ a1 / a2 ≦ 2 is satisfied.
According to the present invention, since a uniform magnetic bias can be applied to the giant
magnetostrictive element, it is possible to effectively reduce the output distortion of the giant
magnetostrictive unit.
[0007]
Preferably, the giant magnetostrictive unit according to the present invention further comprises a
yoke disposed in the axial direction of the giant magnetostrictive element. If a closed magnetic
circuit is configured by providing such a yoke, the magnetic flux density in the giant
magnetostrictive element can be made more uniform, and the magnetic flux density itself can be
increased.
[0008]
Here, when the diameter of the yoke is b3, it is preferable to satisfy 1 ≦ b3 / b1 ≦ 3. If the
relationship between b3 and b1 is set in the above range, it is possible to make the magnetic flux
density sufficiently uniform while preventing an excessive decrease in the magnetic flux density.
[0009]
Preferably, a gap of 0.1 mm or more is provided in the axial direction between the yoke and the
permanent magnet. According to this, it is possible to appropriately suppress the rise of the
magnetic bias at the end of the giant magnetostrictive element.
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[0010]
The permeability of the yoke is preferably 100 or more, and more preferably 1000 or more. This
is because the higher the magnetic permeability of the yoke, the more the magnetic flux density
at the end of the giant magnetostrictive element can be suppressed, and as a result, the magnetic
flux density becomes more uniform.
[0011]
Furthermore, in the present invention, it is preferable that the axial length of the giant
magnetostrictive element and the axial length of the coil be substantially the same. According to
this, the magnetic flux density in the giant magnetostrictive element by the coil can be made
uniform, and the output distortion of the giant magnetostrictive unit can be effectively reduced.
[0012]
As described above, since the magnetostrictive unit according to the present invention has a
uniform magnetic bias in the magnetostrictive element, the output distortion is significantly
increased when used as an actuator or as a pressure sensor. It is possible to reduce the
[0013]
Hereinafter, preferred embodiments of the present invention will be described in detail with
reference to the accompanying drawings.
[0014]
FIG. 1 is a schematic cross-sectional view showing the structure of a giant magnetostrictive unit
10 according to a preferred embodiment of the present invention.
[0015]
As shown in FIG. 1, the giant magnetostrictive unit 10 according to the present embodiment
includes a columnar giant magnetostrictive element 11, a cylindrical coil 12 disposed in the
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radial direction of the giant magnetostrictive element 11, and an axis of the giant
magnetostrictive element 11. A disk-shaped yoke 13 disposed in the direction and a cylindrical
permanent magnet 14 disposed in the radial direction of the coil 12 are provided.
The giant magnetostrictive unit 10 according to the present embodiment can be used as an
actuator for displacing the giant magnetostrictive element 11 by supplying a predetermined
current to the coil 12. Further, the displacement of the giant magnetostrictive element 11 due to
external force can be used as a coil current It is also possible to use as a pressure sensor which
detects as change of.
[0016]
The giant magnetostrictive element 11 is a cylindrical element made of a giant magnetostrictive
material which is displaced in response to the application of a magnetic field and whose
permeability changes in accordance with displacement due to an external force.
The super-magnetostrictive material to be used is not particularly limited, but a supermagnetostrictive material having Tb0.34-Dy0.66-Fe1.90 as a central composition can be used.
The size of the giant magnetostrictive element 11 may be appropriately selected in accordance
with the intended use and output of the giant magnetostrictive unit 10.
[0017]
The super magnetostrictive element 11 is inserted in the hollow portion of the coil 12, and the
coil 12 is used as an electromagnetic conversion means magnetically coupled to the giant
magnetostrictive element 11. Therefore, when a predetermined current is supplied to the coil 12
from a drive circuit (not shown), the coil 12 applies a magnetic field based thereon to the giant
magnetostrictive element 11, and the displacement of the giant magnetostrictive element 11
obtained thereby is a first change of the yoke 13. It can be taken out from the part 13a. That is,
in this case, the giant magnetostrictive unit 10 functions as an actuator. Conversely, when the
external force applied to the first portion 13a of the yoke 13 causes the super magnetostrictive
element 11 to expand and contract, thereby changing the magnetic permeability of the giant
magnetostrictive element 11, the coil 12 detects the current generated thereby. To supply. That
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is, in this case, the giant magnetostrictive unit 10 functions as a pressure sensor.
[0018]
As shown in FIG. 1, in the giant magnetostrictive unit 10 according to the present embodiment,
the axial length of the giant magnetostrictive element 11 and the axial length of the coil 12
substantially coincide with each other. This is to make the magnetic flux density in the giant
magnetostrictive element 11 by the coil 12 uniform, and the output distortion of the giant
magnetostrictive unit 10 is reduced by such a configuration. That is, when the length in the axial
direction of the giant magnetostrictive element 11 is shorter than the length in the axial direction
of the coil 12, the magnetic flux density at the end of the giant magnetostrictive element 11
becomes higher than that in the central portion. When the length in the axial direction of the coil
is longer than the length in the axial direction of the coil 12, the magnetic flux density at the end
of the giant magnetostrictive element 11 is lower than that in the central portion. On the other
hand, if the lengths in the axial direction are made to substantially coincide with each other, the
magnetic flux density in the giant magnetostrictive element 11 can be made substantially
uniform from the end portion to the central portion. However, in the present invention, it is not
essential to substantially match the axial length of the giant magnetostrictive element 11 and the
axial length of the coil 12.
[0019]
As shown in FIG. 1, the yoke 13 is constituted by a first portion 13a provided on one end side of
the giant magnetostrictive element 11 and a second portion 13b provided on the other end side.
There is. The first portion 13a of the yoke 13 functions as an input / output unit which takes out
the displacement of the giant magnetostrictive element 11 or transmits an external force to the
giant magnetostrictive element 11, and the second portion 13b of the yoke 13 is substantially
fixed. Ru.
[0020]
Although it is not essential to provide a yoke in the present invention, if a closed magnetic circuit
is configured by providing this, it is possible to make the magnetic flux density in the giant
magnetostrictive element 11 by the coil 12 and the permanent magnet 14 more uniform and The
magnetic flux density itself can be increased.
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[0021]
In the present embodiment, the diameter b3 of the yoke 13 is set such that the center diameter
(= (inner diameter + outer diameter) / 2) of the permanent magnet 14 is larger than b1.
The relationship between the diameter b3 of the yoke 13 and the central diameter b1 of the
permanent magnet 14 preferably satisfies 1 ≦ b3 / b1 ≦ 3. This is because the diameter b3 of
the yoke 13 is equal to the central diameter b1 of the permanent magnet 14 On the other hand,
the larger the magnetic flux density is, the more the magnetic flux density becomes uniform and
the lower the magnetic flux density. That is, when the relationship between b3 and b1 is set in
the above range, it is possible to make the magnetic flux density sufficiently uniform while
preventing an excessive decrease in the magnetic flux density.
[0022]
As a material of the yoke 13, it is preferable to use a material having a high permeability as much
as possible. Specifically, the permeability (μ) is preferably 100 or more, and more preferably
1000 or more. This is because the higher the magnetic permeability of the yoke 13, the higher
the effect of suppressing the decrease in the magnetic flux density at the end of the giant
magnetostrictive element 11, and a material having a magnetic permeability of 100 or more is
used as the material of the yoke 13. For example, in combination with the configuration of the
present embodiment, it is possible to make the magnetic flux density more uniform. In particular,
if a material having a permeability of 1000 or more is used as the material of the yoke 13, it is
possible to make the magnetic flux density substantially uniform, in combination with the
configuration of the present embodiment. Preferred specific materials include pure iron (μ =
5000 or more), silicon iron (μ = 6000 or more), electromagnetic stainless steel (μ = 4000 or
more), permalloy (μ = 30000 or more), ferrite (μ = 1000 or more) Etc. can be mentioned.
[0023]
The permanent magnet 14 is a cylindrical body surrounding the outside of the coil 12 and serves
to apply a magnetic bias to the giant magnetostrictive element 11. This is because, in the absence
of the magnetic bias, the displacement of the giant magnetostrictive element 11 is not directional
with respect to the direction of the magnetic field.
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[0024]
In the giant magnetostrictive unit 10 according to the present embodiment, the length of the
permanent magnet 14 in the axial direction is a1, and the central diameter of the permanent
magnet 14 (= (inner diameter + outer diameter) / 2) is b1. 0.3 ≦ b1 /A1≦0.7 is set. The reason
for this setting is to give a uniform magnetic bias to the giant magnetostrictive element 11, and
the output distortion of the giant magnetostrictive unit 10 is reduced by such a configuration.
That is, while b1 / a1 <0.3, the magnetic bias at the central portion of the giant magnetostrictive
element 11 is insufficient, and the magnetic bias at the end becomes significantly stronger than
the central portion, while b1 / a1> 0.7 If so, the magnetic bias at the end of the giant
magnetostrictive element 11 becomes significantly weaker than in the central portion. On the
other hand, when the relationship between a1 and b1 is set in the above range, the magnetic bias
in the giant magnetostrictive element 11 can be made uniform from the end portion to the
central portion. Specifically, the magnetic bias strength at the end can be 80% or more and 150%
or less of the magnetic bias strength at the central part. Here, the reason why the magnetic bias
intensity difference at the end with respect to the central part is largely permitted in the positive
direction (more than 100%) is that the problem is larger when the magnetic bias is too strong
compared to when the magnetic bias is too strong. is there.
[0025]
In order to apply a uniform magnetic bias to the giant magnetostrictive element 11, it is
preferable to set 0.45 ≦ b1 / a1 ≦ 0.55.
[0026]
Furthermore, in the giant magnetostrictive unit 10 according to the present embodiment, when
the length of the giant magnetostrictive element 11 in the axial direction is a2, a1 = a2 is set.
As a result, it is possible to apply a uniform magnetic bias to the giant magnetostrictive element
11 while reducing the overall size as much as possible. On the other hand, if a1 <a2, a region in
which the magnetic bias is almost zero may be generated in the super magnetostrictive element
11, and in this case, the magnetic bias becomes extremely nonuniform. Conversely, the case
where a1> a2 will be described later.
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[0027]
In the super magnetostrictive unit 10 having the above configuration, as described above, the
relationship between the length a1 of the permanent magnet 14 in the axial direction and the
central diameter b1 of the permanent magnet 14 is set to 0.3 ≦ b1 / a1 ≦ 0.7. Since the
relationship between the length a1 in the axial direction of the permanent magnet 14 and the
length a2 in the axial direction of the giant magnetostrictive element 11 is set to a1 = a2, the
magnetism uniform in the giant magnetostrictive element 11 is obtained. It becomes possible to
give a bias. Furthermore, in the present embodiment, the yoke 13 is provided in the axial
direction of the giant magnetostrictive element 11, and the relationship between the diameter b3
thereof and the central diameter of the permanent magnet 14 is set to 1 ≦ b3 / b1 ≦ 3. Thus,
the magnetic flux density due to the magnetic bias can be made more uniform.
[0028]
Moreover, in the present embodiment, since the axial length of the giant magnetostrictive
element 11 and the axial length of the coil 12 substantially coincide with each other, the
uniformity of the magnetic flux density in the giant magnetostrictive element 11 by the coil 12 is
uniform. Will be very high.
[0029]
As a result, it is possible to significantly reduce the output distortion in either the case where the
super magnetostrictive unit 10 of the present embodiment is used as an actuator or the case
where it is used as a pressure sensor.
[0030]
FIG. 2 is a schematic cross-sectional view showing the structure of the giant magnetostrictive unit
20 according to another preferred embodiment of the present invention.
[0031]
The giant magnetostrictive unit 20 according to the present embodiment is different from the
above embodiment in that the length a1 of the permanent magnet 14 in the axial direction is
longer than the length a2 of the permanent magnet 14 in the axial direction.
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This is focused on the point that the magnetic bias becomes even more uniform by making the
length a1 in the axial direction of the permanent magnet 14 longer than the length a2 in the
axial direction of the giant magnetostrictive element 11.
[0032]
As the length a1 of the permanent magnet 14 in the axial direction becomes longer than the
length a2 of the magnetostrictive element 11 in the axial direction, the magnetic bias becomes
more uniform, while the magnetic flux density thereof decreases.
Therefore, in the present invention, it is necessary to set the relationship between the length a1
in the axial direction of the permanent magnet 14 and the length a2 in the axial direction of the
giant magnetostrictive element 11 within the range of 1 ≦ a1 / a2 ≦ 2. Thereby, it is possible to
make the magnetic bias substantially uniform while preventing an excessive decrease in
magnetic flux density.
[0033]
FIG. 3 is a schematic cross-sectional view showing the structure of the giant magnetostrictive unit
30 according to still another preferred embodiment of the present invention.
[0034]
The giant magnetostrictive unit 30 according to this embodiment is different from the above
embodiments in that the yoke 13 and the permanent magnet 14 are not in direct contact with
each other, and a gap 31 is provided therebetween.
This is because the provision of the gap 31 can suppress the excessive buildup of the magnetic
bias at the end of the giant magnetostrictive element 11.
[0035]
The width of the gap 31 is preferably 0.1 mm or more in the axial direction.
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This is because if the width of the gap 31 is less than 0.1 mm, the effect of the gap can not be
sufficiently obtained.
[0036]
Also in this embodiment, the length a1 in the axial direction of the permanent magnet 14 may be
set longer than the length a2 in the axial direction of the giant magnetostrictive element 11, but
again, the range of 1 ≦ a1 / a2 ≦ 2 Should be set within.
[0037]
The present invention is not limited to the embodiment described above, and various
modifications are possible within the scope of the invention described in the claims, and they are
also included in the scope of the present invention. It goes without saying that
[0038]
Hereinafter, in order to demonstrate the effect of the present invention, the results of static
magnetic field simulation using a static magnetic field analyzer will be described.
The embodiment described below is a simulation focusing on the magnetic bias by the
permanent magnet, and thus the coil is omitted.
[0039]
Example 1
[0040]
First, assuming a giant magnetostrictive unit having a cross section shown in FIG. 4, the magnetic
flux density along the central axis 11 a of the giant magnetostrictive element 11 was simulated.
The permeability (μ) of the giant magnetostrictive element 11 was 6, and the length a2 in the
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axial direction was 20 mm, and the diameter was 2 mm.
Further, the length a1 of the permanent magnet 14 in the axial direction is also 20 mm, and the
center diameter b1 thereof is 7 mm. The residual magnetic flux density (Br) of the permanent
magnet 14 was 1.25 T, and the magnetic permeability (μ) was 1.05. In Example 1, b1 / a1 =
0.35 and a1 / a2 = 1.
[0041]
In this structure, the magnetic flux density along the central axis 11 a of the giant
magnetostrictive element 11 was simulated. The simulation results are shown in FIG.
[0042]
As shown in FIG. 5, the magnetic flux density along the central axis 11a is substantially uniform
in the axial direction of the giant magnetostrictive element 11, and the end relative to the
magnetic flux density (T1) at the central portion (region about 3 mm from the end, Similarly, the
deviation (= (T2 / T1)-100%) of the magnetic flux density (T2) was confirmed to be about +
48.6%. Moreover, the magnetic flux density (T1) of the center part was 0.2339T.
[0043]
Example 2
[0044]
The magnetic flux density was simulated under the same conditions as Example 1 except that the
central diameter b1 of the permanent magnet 14 was 9 mm.
In the second embodiment, b1 / a1 = 0.45 and a1 / a2 = 1. The simulation results are also shown
in FIG. As shown in FIG. 5, the magnetic flux density along the central axis 11a is substantially
uniform in the axial direction of the giant magnetostrictive element 11, and the deviation of the
magnetic flux density (T2) at the end relative to the magnetic flux density (T1) in the central part
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is It was confirmed to be about + 15.0%. Further, the magnetic flux density (T1) at the central
portion was 0.2601 T, and a value higher than that of Example 1 was obtained.
[0045]
[Example 3]
[0046]
The magnetic flux density was simulated under the same conditions as Example 1 except that the
central diameter b1 of the permanent magnet 14 was 11 mm.
In the third embodiment, b1 / a1 = 0.55 and a1 / a2 = 1. The simulation results are also shown in
FIG. As shown in FIG. 5, the magnetic flux density along the central axis 11a is substantially
uniform in the axial direction of the giant magnetostrictive element 11, and the deviation of the
magnetic flux density (T2) at the end relative to the magnetic flux density (T1) in the central part
is It was confirmed to be about -5.4%. In addition, the magnetic flux density (T1) at the central
portion was 0.2737 T, which was a higher value than in Example 2.
[0047]
Example 4
[0048]
The simulation of the magnetic flux density was performed under the same conditions as in
Example 1 except that the central diameter b1 of the permanent magnet 14 was 13 mm.
In the fourth embodiment, b1 / a1 = 0.65 and a1 / a2 = 1. The simulation results are also shown
in FIG. As shown in FIG. 5, the magnetic flux density along the central axis 11a is substantially
uniform in the axial direction of the giant magnetostrictive element 11, and the deviation of the
magnetic flux density (T2) at the end relative to the magnetic flux density (T1) in the central part
is The magnetic flux density at the end was found to be about -18.0%, but the magnetic flux
density (T1) at the central part was 0.2776 T, and a value as high as that of Example 3 was
obtained.
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[0049]
Comparative Example 1
[0050]
The magnetic flux density was simulated under the same conditions as Example 1 except that the
central diameter b1 of the permanent magnet 14 was 5 mm.
In Comparative Example 1, b1 / a1 = 0.25 and a1 / a2 = 1. The simulation results are also shown
in FIG. As shown in FIG. 5, the magnetic flux density along the central axis 11a rises extremely at
the end of the giant magnetostrictive element 11, and the deviation of the magnetic flux density
(T2) of the end with respect to the magnetic flux density (T1) at the central part is about It
reached + 103.3%.
[0051]
Comparative Example 2
[0052]
The simulation of the magnetic flux density was performed under the same conditions as in
Example 1 except that the central diameter b1 of the permanent magnet 14 was set to 15 mm.
In Comparative Example 2, b1 / a1 = 0.75 and a1 / a2 = 1. The simulation results are also shown
in FIG. As shown in FIG. 5, the magnetic flux density along the central axis 11a drops largely at
the end of the giant magnetostrictive element 11, and the deviation of the magnetic flux density
(T2) at the end with respect to the magnetic flux density (T1) at the central part is about − It
reached 25.8%.
[0053]
[Example 5]
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[0054]
Assuming a super magnetostrictive unit having a cross section shown in FIG. 6, assuming that the
length a1 of the permanent magnet 14 in the axial direction is 24 mm and the central diameter
b1 thereof is 11 mm, the central axis 11a is the same as in Example 1. A simulation of the
magnetic flux density along was conducted.
In Example 5, b1 / a1 = 0.458 and a1 / a2 = 1.2.
[0055]
The simulation results are shown in FIG. As shown in FIG. 7, in the structure of Example 5, it was
confirmed that the deviation of the magnetic flux density (T2) at the end with respect to the
magnetic flux density (T1) at the central part was about + 15.5%. Moreover, the magnetic flux
density (T1) of the center part was 0.2173T.
[0056]
[Example 6]
[0057]
The simulation of the magnetic flux density was performed under the same conditions as
Example 5 except that the length a1 of the permanent magnet 14 in the axial direction was 28
mm and the center diameter b1 thereof was 13 mm.
In Example 5, b1 / a1 = 0.464 and a1 / a2 = 1.4, and the value of b1 / a1 is substantially the
same as in Example 5. The simulation results are also shown in FIG. As shown in FIG. 7, in the
structure of Example 6, the deviation of the magnetic flux density (T2) at the end with respect to
the magnetic flux density (T1) at the central part is about + 10.3%, and the magnetic bias is more
uniform. The magnetic flux density (T1) at the central portion was 0.1859 T, which was lower
than that of Example 5.
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[0058]
[Example 7]
[0059]
The simulation of the magnetic flux density was performed under the same conditions as
Example 5 except that the length a1 of the permanent magnet 14 in the axial direction was 32
mm and the center diameter b1 thereof was 15 mm.
In Example 7, b1 / a1 = 0.469 and a1 / a2 = 1.6, and the value of b1 / a1 is almost the same as in
Examples 5 and 6. The simulation results are also shown in FIG. As shown in FIG. 7, in the
structure of Example 7, the deviation of the magnetic flux density (T2) at the end with respect to
the magnetic flux density (T1) in the central part was about + 6.1%, and the magnetic bias was
more uniform. The magnetic flux density (T1) in the central part was 0.1627 T, which was lower
than that in Example 6.
[0060]
[Example 8]
[0061]
The simulation of the magnetic flux density was performed under the same conditions as
Example 5 except that the length a1 of the permanent magnet 14 in the axial direction was 36
mm and the center diameter b1 thereof was 17 mm.
In Example 8, b1 / a1 = 0.472 and a1 / a2 = 1.8, and the value of b1 / a1 is almost the same as in
Examples 5-7. The simulation results are also shown in FIG. As shown in FIG. 7, in the structure
of Example 8, the deviation of the magnetic flux density (T2) at the end with respect to the
magnetic flux density (T1) in the central part was about + 2.6%, and the magnetic bias was more
uniform. The magnetic flux density (T1) at the central portion was 0.1451 T, which was lower
than that of Example 7.
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[0062]
[Example 9]
[0063]
The magnetic flux density was simulated under the same conditions as Example 5 except that the
length a1 of the permanent magnet 14 in the axial direction was 40 mm and the center diameter
b1 thereof was 19 mm.
In Example 9, b1 / a1 = 0.475 and a1 / a2 = 2, and the value of b1 / a1 is substantially the same
as in Examples 5-8. The simulation results are also shown in FIG. As shown in FIG. 7, in the
structure of Example 9, the deviation of the magnetic flux density (T2) at the end relative to the
magnetic flux density (T1) in the central part was about + 0.1%, and the magnetic bias was more
uniform. The magnetic flux density (T1) in the central part was 0.1312 T, which was lower than
that in Example 8.
[0064]
[Example 10]
[0065]
Assuming a super magnetostrictive unit having a cross section shown in FIG. 8, the simulation of
the magnetic flux density along the central axis 11a was performed in the same manner as in
Example 3 except that the diameter b3 of the yoke 13 was 11 mm.
In Example 10, b1 / a1 = 0.55, a1 / a2 = 1, and b3 / b1 = 1.
[0066]
The simulation results are shown in FIG. As shown in FIG. 9, in the structure of Example 10, it
was confirmed that the deviation of the magnetic flux density (T2) at the end with respect to the
magnetic flux density (T1) at the central part was about + 44.3%. Further, the magnetic flux
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density (T1) at the central portion was 0.3013 T, and a very high value was obtained.
[0067]
[Example 11]
[0068]
With the central axes of the giant magnetostrictive element 11 and the yoke 13 aligned, the
simulation of the magnetic flux density along the central axis 11a was performed in the same
manner as in Example 10 except that the diameter b3 of the yoke 13 was 12 mm.
In Example 11, b1 / a1 = 0.55, a1 / a2 = 1, and b3 / b1 = 1.09.
[0069]
The simulation results are also shown in FIG. As shown in FIG. 9, in the structure of Example 11,
the deviation of the magnetic flux density (T2) at the end relative to the magnetic flux density
(T1) in the central part is about + 44.5%, and the magnetic flux density (T1) in the central part is
0.. The characteristics were 2942 T, and substantially the same characteristics as in Example 10
were obtained.
[0070]
[Example 12]
[0071]
A simulation of the magnetic flux density along the central axis 11a was performed in the same
manner as in Example 10 except that the diameter b3 of the yoke 13 was set to 22 mm while the
central axes of the giant magnetostrictive element 11 and the yoke 13 were aligned.
In Example 11, b1 / a1 = 0.55, a1 / a2 = 1, and b3 / b1 = 2.
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[0072]
The simulation results are also shown in FIG. As shown in FIG. 9, in the structure of Example 11,
the deviation of the magnetic flux density (T2) at the end with respect to the magnetic flux
density (T1) in the central part was about + 9.8%, and very high uniformity was obtained. The
magnetic flux density (T1) in the central part was 0.1773 T, which was lower than that in
Example 10.
[0073]
[Example 13]
[0074]
A simulation of the magnetic flux density along the central axis 11a was performed in the same
manner as in Example 10 except that the diameter b3 of the yoke 13 was set to 33 mm while the
central axes of the giant magnetostrictive element 11 and the yoke 13 were aligned.
In Example 12, b1 / a1 = 0.55, a1 / a2 = 1, and b3 / b1 = 3.
[0075]
The simulation results are also shown in FIG. As shown in FIG. 9, in the structure of Example 12,
the deviation of the magnetic flux density (T2) at the end with respect to the magnetic flux
density (T1) in the central part was about + 2.7%, and very high uniformity was obtained. The
magnetic flux density (T1) in the central part was 0.1108 T, which was lower than that in
Example 12.
[0076]
Comparative Example 3
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[0077]
Assuming a super magnetostrictive unit having a cross section shown in FIG. 10, the simulation
of the magnetic flux density along the central axis 11a is performed in the same manner as in
Example 1 except that the length a1 of the permanent magnet 14 in the axial direction is 16 mm.
The
In Comparative Example 3, b1 / a1 = 0.438 and a1 / a2 = 0.8.
[0078]
The simulation results are shown in FIG. As shown in FIG. 11, in the structure of Comparative
Example 3, it was confirmed that a region in which the magnetic flux density is substantially zero
is generated in the giant magnetostrictive element 11.
[0079]
Example 14
[0080]
Assuming a super magnetostrictive unit having a cross section shown in FIG. 12, the magnetic
flux along the central axis 11a is the same as in Example 11 except that a gap 31 of 0.1 mm is
provided between the yoke 13 and the permanent magnet 14 Simulation of density was
performed.
[0081]
The simulation results are shown in FIG.
The results of Example 11 (without a gap) are also shown in FIG.
As shown in FIG. 13, in the structure of Example 14, the deviation of the magnetic flux density
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(T2) at the end with respect to the magnetic flux density (T1) in the central part is about + 40.0%,
which is more uniform than in Example 11. .
[0082]
[Example 15]
[0083]
A simulation of the magnetic flux density along the central axis 11 a was performed in the same
manner as in Example 14 except that the gap 31 was set to 0.2 mm.
[0084]
The simulation results are also shown in FIG.
As shown in FIG. 13, in the structure of Example 15, the deviation of the magnetic flux density
(T2) at the end relative to the magnetic flux density (T1) in the central part is about + 35.8%,
which is more uniform than in Example 14. The
[0085]
[Example 16]
[0086]
A simulation of the magnetic flux density along the central axis 11 a was performed in the same
manner as in Example 14 except that the gap 31 was set to 0.3 mm.
[0087]
The simulation results are also shown in FIG.
As shown in FIG. 13, in the structure of Example 16, the deviation of the magnetic flux density
(T2) at the end relative to the magnetic flux density (T1) in the central part is about + 31.6%,
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which is more uniform than that of Example 15. The
[0088]
[Example 17]
[0089]
A simulation of the magnetic flux density along the central axis 11 a was performed in the same
manner as in Example 14 except that the gap 31 was set to 0.4 mm.
[0090]
The simulation results are also shown in FIG.
As shown in FIG. 13, in the structure of Example 17, the deviation of the magnetic flux density
(T2) at the end with respect to the magnetic flux density (T1) in the central part is about + 28.1%,
which is more uniform than in Example 16. The
[0091]
[Example 18]
[0092]
A simulation of the magnetic flux density along the central axis 11 a was performed in the same
manner as in Example 14 except that the gap 31 was set to 0.6 mm.
[0093]
The simulation results are also shown in FIG.
As shown in FIG. 13, in the structure of Example 18, the deviation of the magnetic flux density
(T2) at the end relative to the magnetic flux density (T1) in the central part is about + 22.0%,
which is more uniform than in Example 17. The
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[0094]
[Example 19]
[0095]
A simulation of the magnetic flux density along the central axis 11 a was performed in the same
manner as in Example 14 except that the gap 31 was set to 0.8 mm.
[0096]
The simulation results are also shown in FIG.
As shown in FIG. 13, in the structure of Example 19, the deviation of the magnetic flux density
(T2) at the end with respect to the magnetic flux density (T1) in the central part is about + 16.4%,
which is more uniform than in Example 18. The
[0097]
[Example 20]
[0098]
A simulation of the magnetic flux density along the central axis 11 a was performed in the same
manner as in Example 14 except that the gap 31 was set to 1.0 mm.
[0099]
The simulation results are also shown in FIG.
As shown in FIG. 13, in the structure of Example 20, the deviation of the magnetic flux density
(T2) at the end relative to the magnetic flux density (T1) in the central part is about + 12.0%,
which is more uniform than in Example 19. The
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[0100]
It is a schematic sectional drawing which shows the structure of the super magnetostriction unit
10 by preferable embodiment of this invention.
It is a schematic sectional drawing which shows the structure of the super-magnetostriction unit
20 by preferable other embodiment of this invention.
It is a schematic sectional drawing which shows the structure of the super-magnetostriction unit
30 by preferable other embodiment of this invention.
It is the cross-section of the super-magnetostrictive unit assumed in static magnetic field
simulation of Examples 1-4 and comparative examples 1 and 2.
It is a graph which shows the simulation result of Examples 1-4 and Comparative Examples 1 and
2.
It is a cross-section of the super-magnetostrictive unit assumed in static magnetic field simulation
of Examples 5-9.
It is a graph which shows the simulation result of Examples 5-9. It is a cross-section of the supermagnetostrictive unit assumed in static magnetic field simulation of Examples 10-13. It is a
graph which shows the simulation result of Examples 10-13. It is a cross-sectional structure of
the giant magnetostrictive unit assumed in the static magnetic field simulation of Comparative
Example 3. 15 is a graph showing simulation results of Comparative Example 3; It is a crosssection of the super-magnetostrictive unit assumed in static magnetic field simulation of
Examples 14-20. It is a graph which shows the simulation result of Examples 14-20.
Explanation of sign
[0101]
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10, 20, 30 giant magnetostrictive unit 11 giant magnetostrictive element 11a central axis 12 coil
13 yoke 13a first portion of yoke 13b second portion of yoke 14 permanent magnet 31 gap a1
axial length of permanent magnet a2 giant magnetostrictive Length of element in axial direction
b1 Center diameter of permanent magnet b3 Diameter of yoke
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