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JPH0923497

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DESCRIPTION JPH0923497
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
magnetic field application mechanism of a magnetostrictive rod that causes magnetostrictive
vibration in a magnetostrictive rod in an industrial product utilizing magnetostriction of a
magnetostrictive rod such as a large underwater power source, actuator, or speaker. is there.
[0002]
2. Description of the Related Art Heretofore, as a technique in such a field, for example, there has
been one shown in the following document. Technical Report (1993-8), The Institute of
Electronics, Information and Communication Engineers, Akira Kawamori et al., "Low-frequency
sound source using giant magnetostrictive material" P. 57-64 FIG. 2 is a cross-sectional view
showing the structure of a conventional magnetostrictive vibrator. The magnetostrictive vibrator
is, for example, a magnetostrictive vibrator provided to a large power output in water, and has a
magnetostrictive rod 1 formed of a rare earth alloy. A solenoid coil 2 for driving a
magnetostrictive rod is wound around the outer periphery of the magnetostrictive rod 1. The
reason for using the solenoid coil 2 is to reduce the leakage of the magnetic field and to increase
the energy efficiency. A yoke material 3 of high magnetic permeability is attached to both ends of
the magnetostrictive rod 1. A permanent magnet 4 for applying a magnetic bias is attached to the
opposite side of the magnetostrictive rod 1 in each yoke material 3. The solenoid coil 2 is
configured to be supplied with an alternating current from a current source 5. When an
alternating current is applied from the current source 5, the solenoid coil 2 generates a magnetic
field, which is applied to the yoke material 3. The yoke material 3 concentrates the magnetic flux
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on the magnetostrictive lot 1 to give an alternating magnetic field. Thereby, the magnetostrictive
lot 1 performs magnetostrictive oscillation centering on the magnetic bias point set by the
magnets 4 on both sides.
[0003]
However, the conventional magnetostrictive vibrator has the following problems. When a large
current for driving magnetostriction flows, the solenoid coil 2 generates heat, and the
temperature of the magnetostrictive rod 1 around and inside the solenoid coil 2 rises. The
physical characteristics of the rare earth alloy constituting the magnetostrictive rod 1 may
change due to the temperature rise, and there is a problem that the characteristics of the
magnetostrictive vibration deteriorate. Further, both ends of the yoke material 3 become a
magnetic field, resulting in a demagnetizing field. Therefore, it has been difficult to apply a strong
magnetic bias.
[0004]
According to a first aspect of the present invention, there is provided a magnetostrictive rod
which is formed using a rare earth alloy and vibrates in the axial direction based on an applied
alternating magnetic field to solve the above problems. The magnetic field application
mechanism of the magnetostrictive rod for applying a magnetic field is configured as follows.
That is, the magnetic field application mechanism of the magnetostrictive rod of the first
invention comprises a current source for outputting a drive current in which an alternating
current is superimposed on a direct current, and both ends of the magnetostrictive rod. And a
solenoid coil which is wound around a part of the yoke material and which applies a magnetic
field based on the drive current to the yoke material. The second invention is a magnetic field
application mechanism of a magnetostrictive rod which is formed using a rare earth alloy and
vibrates in the axial direction based on an applied alternating magnetic field, and applies the
alternating magnetic field. I have to. That is, a current source for outputting a DC or AC driving
current, a yoke material attached to both ends of the magnetostrictive rod and formed of a high
permeability material forming a closed loop of magnetic flux for the magnetostrictive lot, The
yoke material includes a DC coil and an AC coil wound around a part of the yoke material, and
the magnetic field corresponding to the DC and AC driving currents respectively input to the DC
coil and the AC coil. And a solenoid coil for giving.
[0005]
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According to a third invention, in the magnetic field application mechanism of the
magnetostrictive rod of the first or second invention, a heat insulating mechanism is provided
between the solenoid coil and the magnetostrictive rod. According to a fourth invention, in the
magnetic field application mechanism of the magnetostrictive rod of the first, second or third
invention, the yoke material is formed in three or more parts, and an axial compressive stress is
applied to the magnetostrictive rod. Configuration. According to a fifth invention, in the magnetic
field application mechanism of the magnetostrictive rod of the first, second, third or fourth
invention, a heat radiation plate is provided at a non-wound portion of the solenoid coil of the
yoke material. A sixth aspect of the invention is the magnetic field application mechanism of the
magnetostrictive rod according to the first, second, third, fourth or fifth aspect of the present
invention, wherein a portion of the yoke material attached to the magnetostrictive rod is a part of
a rotating ellipse. The magnetostrictive rod is attached to the concave surface of the shape.
[0006]
According to the first aspect of the invention, since the magnetic field application mechanism of
the magnetostrictive rod is configured as described above, the current source generates a drive
current in which an alternating current is added to the direct current and supplies it to the
solenoid coil. The direct current is for magnetic biasing and the alternating current is for
alternating magnetic fields. Here, the solenoid coil is wound around the yoke material, not the
magnetostrictive rod. Therefore, the heat generated in the solenoid coil does not directly reach
the magnetostrictive rod. The solenoid coil generates an alternating magnetic field centering on a
magnetic bias corresponding to the drive current. A magnetic flux is given to the
magnetostrictive rod through the yoke material, and the magnetostrictive rod oscillates
magnetostrictively based on an alternating magnetic field centering on the magnetic bias.
According to the second aspect of the invention, direct current and alternating current drive
currents are output from the current source and supplied to the solenoid coil. The DC coil in the
solenoid coil generates a magnetic bias corresponding to a DC drive current. The AC coil
generates an alternating magnetic field corresponding to an AC drive current. That is, an
alternating magnetic field centering on the magnetic bias corresponding to the drive current is
generated in the solenoid coil. Here, the solenoid coil is wound around the yoke material, not the
magnetostrictive rod. Therefore, the heat generated in the solenoid coil does not directly reach
the magnetostrictive rod. A magnetic flux is given to the magnetostrictive rod through the yoke
material, and the magnetostrictive rod oscillates magnetostrictively based on an alternating
magnetic field centering on the magnetic bias. According to the third invention, the heat
insulation mechanism prevents the heat propagation between the solenoid coil and the
magnetostrictive rod in the first or second invention.
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[0007]
According to the fourth invention, in the first, second, or third invention, axial compressive stress
is applied to the magnetostrictive rod by the yoke material formed in three or more parts.
According to the fifth invention, the yoke material is cooled by the heat radiation plate provided
to the yoke material in the first, second, third or fourth invention. That is, the heat generated by
the solenoid coil that conducts the yoke material is released by the heat radiation plate.
According to the sixth invention, the connecting portion between the yoke material and the
magnetostrictive rod in the first, second, third, fourth or fifth invention has a shape obtained by
hollowing out the yoke material at a part of the spheroid. . As a result, the magnetic field applied
to the magnetostrictive rod becomes uniform. Therefore, the problem can be solved.
[0008]
FIG. 1 is a cross-sectional view of a magnetic field application mechanism of a magnetostrictive
rod showing a first embodiment of the present invention. A yoke material 11 is attached to both
ends of the magnetostrictive rod 10 formed of a rare earth alloy so as to form a loop of magnetic
flux. A solenoid coil 12 for excitation is wound around a portion of the yoke material 11 apart
from the magnetostrictive rod 10. The yoke material 11 is made of, for example, a laminate of
silicon steel plates, or a member having high permeability and low resistivity such as soft
magnetic sintered metal. In addition, the yoke material 11 is constituted by three parts of parts
11a and 11b at both ends of the magnetostrictive rod 10 and a part 11c in which the solenoid
coil 12 is wound, and a compressive stress, that is, a strong magnetic bias is applied to the
magnetostrictive rod 10. It has become. A heat insulating mechanism 13 such as a heat
insulating material is provided between the solenoid coil 12 and the magnetostrictive rod 10. A
current source 14 is connected to the solenoid coil 12. Next, the operation of the magnetic field
application mechanism of the magnetostrictive rod of FIG. 1 will be described with reference to
FIG. FIG. 3 is a diagram showing the current supplied by the current source in FIG.
[0009]
The current source 14 superimposes an alternating current for alternating magnetic field
excitation on a direct current for magnetic bias and supplies a driving current as shown in FIG. 3
to the solenoid coil 12. A drive current is applied to the solenoid coil 12, which generates a
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magnetic field and applies a magnetic flux to the yoke material 11. The yoke material 11
transmits the magnetic flux to the magnetostrictive rod 10. A magnetic bias and an alternating
magnetic field for excitation are applied to the magnetostrictive rod 10, and a magnetostriction
phenomenon occurs in the magnetostrictive rod 10. Here, the heat generated by the solenoid coil
12 is shut off by the heat insulating mechanism 13, and the magnetostrictive rod 10 and its
surroundings do not rise in temperature. As described above, in the first embodiment, since the
solenoid coil 12 is wound around the yoke member 11, the heat generation of the solenoid coil
12 is not directly transmitted to the magnetostrictive rod 10, so that the temperature rise of the
magnetostrictive lot 10 is small. It has become. Further, since the heat insulating mechanism 13
is provided, the radiant heat of the solenoid coil 12 is shut off, and the effect is further enhanced.
Therefore, performance degradation in the magnetostrictive rod 10 is prevented. Further, since
the thermal influence on the magnetostrictive rod 10 and the periphery thereof is small, it is
possible to flow a large current to the solenoid coil 12, and the magnetic bias can be set by the
direct current. Thus, it also becomes possible to control the amount of magnetic bias. On the
other hand, since the yoke material 11 has a structure forming a closed loop of magnetic flux, the
influence of the demagnetizing field can be eliminated.
[0010]
FIG. 4 is a cross-sectional view showing the structure of the underwater wave transmitter using
FIG. 1, and the elements common to the elements in FIG. 1 are given the same reference
numerals. In this underwater wave transmitter, the same magnetostrictive rod 10 as in FIG. 1 and
a mechanism composed of a yoke material 11, a solenoid coil 12 and a current source 14 are
incorporated. The vibrating flanges 21 and 22 are attached to both sides of the parts 11 a and
11 b of the yoke material 11. The lower part of the vibrating flange 21, the parts 11a and 11b of
the yoke material 11, the magnetostrictive rod 10, and the vibrating flange 22 are
accommodated in the case 23, and a part of the part 11c of the yoke material 11 and a solenoid
wound around it The coil 12 is housed in the radiator 24. In this case, the case 23 is a heat
insulating mechanism for the magnetostrictive rod 10. A magnetostrictive material such as a rare
earth alloy used as a giant magnetostrictive material has a large change in performance due to
the ambient temperature of the material. In addition, since the permeability of the
magnetostrictive material is small, it is desirable to suppress the influence of the demagnetizing
field and to give a slightly large magnetic bias. In FIG. 1, even if a large current is supplied to the
solenoid coil 12, there is no problem, which is effective for an underwater wave transmitter as
shown in FIG. 4 which outputs a large power, an actuator, a speaker and the like.
[0011]
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Second Embodiment FIG. 5 is a cross-sectional view of a magnetic field application mechanism of
a magnetostrictive rod according to a second embodiment of the present invention, and the
elements common to the elements in FIG. There is. The magnetic field application mechanism of
the magnetostrictive rod is provided with a yoke material 11, a solenoid coil 12, a heat insulation
mechanism 13 and a current source 14 similar to those of FIG. And, unlike FIG. 1, two heat
radiation plates 31 and 32 are attached to the connecting portion of the magnetostrictive rod 10
and the solenoid coil 12 of the yoke material 11. The heat radiation plates 31 and 32 are
respectively formed of a material having good heat conductivity. When the heat radiation plates
31, 32 are cooled by water cooling or the like, among the heat generated by the solenoid coil 12,
the heat conducted in the yoke material 12 and transmitted to the magnetostrictive rod 10
escapes to the cooling water side. As described above, in the second embodiment, the heat
radiation plates 31 and 32 are attached to the yoke material 12 connecting the magnetostrictive
rod 10 and the solenoid coil 12, and the yoke material 12 is attached to the heat radiation plates
31 and 32. Heat is prevented from being transmitted to the magnetostrictive rod 10. Thus, the
effect of the first embodiment is further ensured.
[0012]
Third Embodiment FIG. 6 is a cross-sectional view of a magnetic field application mechanism of a
magnetostrictive rod showing a third embodiment of the present invention, and the elements
common to the elements in FIG. There is. In this magnetic field application mechanism, both ends
of the magnetostrictive rod 10 are attached to a yoke member 40 different from the first
embodiment. A solenoid coil 12 similar to that shown in FIG. 1 is wound around a portion of the
yoke member 40 away from the magnetostrictive rod 10, and the solenoid coil 12 is connected
to the current source 14. Similarly to the yoke material 11 in FIG. 1, the yoke material 40 is made
of, for example, a laminate of silicon steel plates, or a member having high permeability and low
resistivity such as soft magnetic sintered metal. The attachment portions 40a and 40b of the
magnetostrictive rod 10 on both sides of the yoke member 40 are formed by being cut out by a
spheroid. The solenoid coil 12 generates a magnetic field based on the drive current supplied
from the current source 14. The yoke material 40 applies a magnetic flux corresponding to the
magnetic field generated by the solenoid coil 12 to the magnetostrictive rod 10. Here, the
attachment portions 40 a and 40 b of the yoke material 40 have a shape that is hollowed out by
a spheroid, and the yoke material 40 gives a uniform magnetic field to the magnetostrictive rod
10.
[0013]
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As described above, in the third embodiment, the portion to which the magnetostrictive rod 10 is
attached is provided with the yoke member 40 having a shape that is hollowed out by a spheroid.
As a result, the magnetic field applied to the magnetostrictive rod 10 becomes uniform, and the
magnetostrictive characteristics become good. The present invention is not limited to the above
embodiment, and various modifications are possible. For example, the heat insulation mechanism
13 or the heat radiation plates 31 and 32 used in the first and second embodiments are attached
to the magnetic field application mechanism of the third embodiment so as to suppress the
temperature rise of the magnetostrictive rod 10 and its surroundings. You may Further, in the
first to third embodiments, the current source 14 superimposes direct current and alternating
current and supplies the current to the solenoid coil 12. However, the solenoid coil 12 is formed
of a direct current coil and an alternating current coil. Even if 14 applies direct current to its
direct current coil and alternating current to its alternating current coil, the magnetostrictive rod
10 vibrates corresponding to the alternating magnetic field centering on the magnetic bias as in
the above embodiment. Can.
[0014]
As described above in detail, according to the first invention, the magnetic field application
mechanism of the magnetostrictive rod is attached to both ends of the magnetostrictive rod to
form a closed loop of magnetic flux, and the yoke material Since the solenoid coil wound around
a part of the motor and the current source for applying the drive current obtained by
superimposing the alternating current to the direct current to the solenoid coil are less affected
by the heat generated in the solenoid coil, The temperature change of the magnetostrictive rod
and its surroundings is reduced. Therefore, the characteristic of magnetostrictive vibration can
be maintained favorably. Further, the magnetic bias for the magnetostrictive lot can be adjusted
by the current, and the influence of the demagnetizing field is eliminated. Therefore, an axial
compressive stress is applied to the magnetostrictive rod. That is. It becomes possible to apply a
strong magnetic bias, and it becomes easy to apply to products with large output power utilizing
the magnetostriction phenomenon. According to the second invention, a yoke material attached
to both ends of the magnetostrictive rod to form a closed loop of magnetic flux, and a solenoid
coil wound around a part of the yoke material and having a DC current coil and an AC coil And
the current source for supplying a direct current and alternating current drive current to the
solenoid coil, so that the influence of heat generated in the solenoid coil becomes small as in the
first invention, and the temperature change of the magnetostrictive rod and its periphery
Becomes smaller. Therefore, the characteristic of magnetostrictive vibration can be maintained
favorably. Further, the magnetic bias for the magnetostrictive lot can be adjusted by the current,
and there is no influence of the demagnetizing field. Therefore, an axial compressive stress is
applied to the magnetostrictive rod. That is. It becomes possible to apply a strong magnetic bias,
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and it becomes easy to apply to products with large output power utilizing the magnetostriction
phenomenon.
[0015]
According to the third invention, since the heat insulation mechanism is provided in the first or
second invention, the temperature rise of the magnetostrictive rod is suppressed, and the effect
of the first or second invention is further ensured. According to the fourth invention, since the
yoke material is formed in three or more parts, compressive stress in the axial direction is more
strongly applied to the magnetostrictive rod than in the first, second or third invention. .
According to the fifth invention, since the heat radiation plate is provided, the heat generated by
the solenoid coil conducting the yoke material is released by the heat radiation plate and the heat
is not transmitted to the magnetostrictive rod. Therefore, the effects of the first to fourth
inventions can be further ensured. According to the sixth invention, the connecting portion
between the yoke material and the magnetostrictive lot has a shape obtained by hollowing out
the yoke material at a part of the spheroid, so that the magnetic field applied to the
magnetostrictive rod becomes uniform, The accuracy of the magnetostrictive vibration is
improved.
[0016]
Brief description of the drawings
[0017]
1 is a cross-sectional view of the magnetic field application mechanism of the magnetostrictive
rod showing the first embodiment of the present invention.
[0018]
2 is a cross-sectional view showing the structure of a conventional magnetostrictive vibrator.
[0019]
3 is a diagram showing the current supplied by the current source in FIG.
[0020]
4 is a cross-sectional view showing the structure of the underwater wave transmitter using FIG.
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[0021]
5 is a cross-sectional view of the magnetic field application mechanism of the magnetostrictive
rod showing a second embodiment of the present invention.
[0022]
6 is a cross-sectional view of the magnetic field application mechanism of the magnetostrictive
rod showing a third embodiment of the present invention.
[0023]
Explanation of sign
[0024]
DESCRIPTION OF SYMBOLS 10 Magnetostrictive rod 11, 40 Yoke material 12 Solenoid coil 13
Heat insulation mechanism 14 Current source 31, 32 Thermal radiation board
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