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JP2005080462

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DESCRIPTION JP2005080462
PROBLEM TO BE SOLVED: To efficiently apply a magnetic field from a magnetic field excitation
coil to a magnetostrictive element. SOLUTION: The magnetostrictive element 10 is formed into a
cylindrical shape, and the magnetic field exciting coils 12 and 14 wound around the inner
peripheral portion and the outer peripheral portion of the cylindrical magnetostrictive element
10 are disposed. [Selected figure] Figure 1
Magnetostrictive actuator
[0001]
The present invention relates to a magnetostrictive actuator provided with a magnetostrictive
element that generates magnetostriction by the application of an external magnetic field.
[0002]
In general, a magnetostrictive actuator including a magnetostrictive element that generates a
magnetostriction by application of an external magnetic field using a magnetostriction
phenomenon is known as an actuator that generates vibration or displacement.
[0003]
A Ni-based magnetostrictive alloy, an Fe-Al-based magnetostrictive alloy, and a ferrite-based
magnetostrictive alloy are mainly used as the material of the magnetostrictive element of the
magnetostrictive actuator.
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1
Recently, as a material of this magnetostrictive element, a rare earth metal-transition metal
supermagnetostrictive alloy that can generate a displacement larger than that of this Ni-based
magnetostrictive alloy, Fe-Al-based magnetostrictive alloy, or ferrite-based magnetostrictive alloy
by one digit or more It is done.
[0004]
Whether this magnetostrictive element expands or contracts depends on the constituent material
of this magnetostrictive element, and in the case of a Ni-based magnetic alloy, it contracts mainly,
Fe-Al-based magnetostrictive alloy, ferrite-based magnetostrictive alloy, rare earth metaltransition metal-based supermagnetostriction It mainly stretches in alloys.
[0005]
As shown in FIG. 2, a conventional magnetostrictive actuator is wound around the inner
periphery of a yoke 2 formed of a cylindrical ferromagnetic material so as to surround, for
example, a columnar magnetostrictive element 1 of rare earth metal-transition metal
supermagnetostrictive alloy. A magnetic field exciting coil 3 mounted is provided, and a drive rod
4 is provided, for example, on the upper side of the magnetostrictive element 1 (see Patent
Document 1).
[0006]
In FIG. 2, when current flows through the magnetic field excitation coil 3, a magnetic field is
generated, and this magnetic field is applied to the magnetostrictive element 1, and the
magnetostrictive element 1 expands (contracts) by the applied magnetic field to displace the
drive rod 4. Do.
[0007]
Although not described in the example of FIG. 2, in the case of the magnetostrictive actuator
using the magnetostrictive element 1, the amount of distortion when the magnetic field is applied
by applying stress from the outside to the magnetostrictive element 1 in advance It has been
found that it can be made larger.
The stress includes compressive stress and tensile stress, but this also depends on the material
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2
that constitutes the magnetostrictive element 1.
[0008]
For example, when a tensile stress is applied to a Ni-based magnetostrictive alloy and a
compressive stress is applied mainly to a Fe-Al-based magnetostrictive alloy, a ferrite-based
magnetostrictive alloy, or a rare earth metal-transition metal supercoiled magnetostrictive alloy,
the amount of strain can be increased.
Unexamined-Japanese-Patent No. 3-169087 gazette
[0009]
By the way, while the reduction in weight and weight of various products is progressing in recent
years, energy saving is required.
For that purpose, in the magnetostrictive actuator as shown in FIG. 2, it is required to increase
the amount of magnetostriction of the magnetostrictive element 1 by the same current flowing
through the magnetic field excitation coil 3.
[0010]
That is, how small the current flowing through the magnetic field excitation coil 1 is, and how
large the magnetic field supplied to the magnetostrictive element 1 is, is required.
[0011]
In the conventional magnetostrictive actuator, as shown in FIG. 2, the magnetic field exciting coil
3 is arranged to surround the outer periphery of the magnetostrictive element 1 using a
cylindrical magnetostrictive element 1. Therefore, as shown in FIG. It is difficult to efficiently
apply the magnetic field excited from the magnetic field excitation coil 3 to the central portion of
the magnetostrictive element 1, and the distribution of the applied magnetic field is generated in
the radial direction of the magnetostrictive element 1.
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[0012]
Furthermore, since the magnetic field exciting coil 3 of this magnetostrictive actuator has an
inductance component, the impedance of the magnetic field exciting coil 3 becomes high when
the frequency of the flowing current becomes high.
[0013]
An object of the present invention is to make it possible to efficiently apply a magnetic field from
a magnetic field excitation coil to a magnetostrictive element in view of the above point.
[0014]
In the magnetostrictive actuator of the present invention, the magnetostrictive element has a
cylindrical shape, and magnetic excitation coils wound around the inner and outer peripheral
portions of the cylindrical magnetostrictive element are disposed.
[0015]
Further, in the magnetostrictive actuator of the present invention, the strengths of the magnetic
fields excited from the magnetic field excitation coils disposed on the inner and outer peripheral
portions of the cylindrical magnetostrictive element are added and reinforced within the
cylindrical magnetostrictive element. The
[0016]
Further, in the magnetostrictive actuator of the present invention, magnetic field exciting coils
respectively wound around the inner and outer peripheral portions of the cylindrical
magnetostrictive element are connected in parallel.
[0017]
According to the present invention, the magnetostrictive element is formed in a cylindrical shape,
and the magnetic field excitation coil is disposed on the inner and outer peripheral portions of
the cylindrical magnetostrictive element. Therefore, the magnetic field excitation coil for the
inner and outer peripheral portions is excited The magnetic field can be efficiently applied to the
magnetostrictive element.
[0018]
Further, according to the present invention, since the magnetic field exciting coils respectively
disposed on the inner and outer peripheral portions of the magnetostrictive element having a
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cylindrical shape are connected in parallel, the inductance component of the input impedance of
the magnetic field exciting coil can be reduced. .
[0019]
Hereinafter, an example of the best mode for carrying out the magnetostrictive actuator of the
present invention will be described with reference to FIGS. 1A and 1B.
[0020]
In this example, as shown in FIGS. 1A and 1B, the magnetostrictive element 10 is formed in a
cylindrical shape.
As a material of the magnetostrictive element 10, a Ni-based magnetostrictive alloy, an Fe-Albased magnetostrictive alloy, a ferrite-based magnetostrictive alloy, a rare earth metal-transition
metal-based super magnetostrictive alloy, or the like is used.
Whether this magnetostrictive element 10 expands or contracts depends on the constituent
material of this magnetostrictive element 10, and although it contracts mainly in a Ni-based
magnetostrictive alloy, Fe-Al-based magnetostrictive alloy, ferrite-based magnetostrictive alloy,
rare earth metal In transition metal-based giant magnetostrictive alloys, it mainly elongates.
[0021]
In this example, a rare earth metal-transition metal supermagnetostrictive alloy is used as the
magnetostrictive element 10 to form a cylindrical shape.
[0022]
In the present embodiment, as shown in FIGS. 1A and 1B, a magnetic field excitation coil 12
wound around a cylindrical yoke 11 of a cylindrical ferromagnetic body is disposed on the inner
peripheral portion of the cylindrical magnetostrictive element 10.
In this case, a slight gap is provided between the inner peripheral surface of the cylindrical
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magnetostrictive element 10 and the outer peripheral surface of the magnetic field exciting coil
12 as shown in FIG. 1B so that the magnetostrictive element 10 can be moved.
[0023]
When a current in one direction is supplied to the magnetic field excitation coil 12, the direction
of the magnetic line of force a generated by the magnetic field excitation coil 12 excites a
magnetic field as shown from the top to the bottom of the magnetostrictive element 10 as shown
in FIG. 1A. When a current in the other direction flows, the magnetic field in the reverse direction
is excited.
[0024]
Further, in the present embodiment, a magnetic field exciting coil 14 wound around an inner
peripheral portion of a cylindrical yoke 13 made of a cylindrical ferromagnetic material is
disposed on an outer peripheral portion of the cylindrical magnetostrictive element 10.
In this case, a slight gap is provided between the outer peripheral surface of the cylindrical
magnetostrictive element 10 and the inner peripheral surface of the magnetic field exciting coil
14 as shown in FIG. 1B so that the magnetostrictive element 10 can be moved.
[0025]
Further, in this example, when a current in one direction flows through the magnetic field
excitation coil 14, the direction of the magnetic line of force b generated by the magnetic field
excitation coil 14 is from above to below the magnetostrictive element 10 as shown in FIG. 1A.
The magnetic field to be directed is excited, and when the current in the other direction flows,
the magnetic field in the reverse direction is excited.
[0026]
In this case, in this example, magnetic lines of force a and b from the magnetic field exciting coils
12 and 14 disposed on the inner and outer peripheral portions of the cylindrical
magnetostrictive element 10 are added in the magnetostrictive element 10 and The strength of
the magnetic field excited from the magnetic field exciting coils 12 and 14 is added in the inside
of the cylindrical magnetostrictive element 10, so that the magnetic field can be applied
efficiently by strengthening each other.
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[0027]
In the present embodiment, the magnetic field exciting coils 12 and 14 are connected in parallel.
In this case, the inductance component of the combined input impedance of the magnetic field
excitation coils 12 and 14 can be reduced, which is particularly advantageous when supplying a
high frequency current to the magnetic field excitation coils 12 and 14.
[0028]
Further, in FIG. 1A, reference numeral 15 denotes a lower yoke in which the lower end of the
cylindrical magnetostrictive element 10, the lower end of the cylindrical yoke 11 and the lower
end of the cylindrical yoke 13 are respectively fixed. The drive rod 16 is provided movably.
[0029]
In FIG. 1A, when current flows through the magnetic field exciting coils 12 and 14, a magnetic
field is generated, and this magnetic field is applied to the magnetostrictive element 10, and this
magnetostrictive element 10 expands (contracts) by the applied magnetic field to drive the rod
16. Displace.
[0030]
According to this example, the magnetostrictive element 10 is formed in a cylindrical shape, and
the magnetic field excitation coils 12 and 14 are disposed on the inner and outer peripheral
portions of the cylindrical magnetostrictive element 10. Therefore, the magnetic field excitation
of the inner and outer peripheral portions The magnetic field excited by the coils 12 and 14 can
be applied efficiently to the magnetostrictive element 10 with a strong magnetic field.
[0031]
Further, according to the present embodiment, since the magnetic field excitation coils
respectively disposed on the inner and outer peripheral portions of the cylindrical
magnetostrictive element 10 are connected in parallel, the combined input impedance of the
magnetic field excitation coils 12 and 14 can be obtained. It is possible to reduce the inductance
component, which is advantageous when supplying a high frequency current to the coils 12 and
14 for magnetic field excitation.
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[0032]
The present invention is not limited to the above-described example, and it goes without saying
that various other configurations can be adopted without departing from the scope of the present
invention.
[0033]
The example of embodiment of the magnetostrictive actuator of this invention is shown, A is a
longitudinal cross-sectional view, B is BB sectional drawing of A figure.
It is a longitudinal cross-sectional view which shows the example of the conventional
magnetostrictive actuator.
Explanation of sign
[0034]
10. Magnetostrictive element 11 Columnar yoke 12, 14 Coil for magnetic field excitation 13.
Cylindrical yoke 15. Lower yoke 16. Drive rod
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