JPH0576194

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DESCRIPTION JPH0576194
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
high magnetostrictive rare earth alloy for protecting the high magnetostrictive rare earth alloy
from breakage or the like in various driving devices such as an underwater wave transmitter
using the high magnetostrictive rare earth alloy. It relates to a protection mechanism.
[0002]
2. Description of the Related Art Heretofore, as a technique in such a field, for example, there
have been described in the following documents. Literature; UDT CONFERENCE (1991) (France)
Fclaeyssen D, Boucher "Design of Lanthanide Magnet tactical Sonar Projectors (DESIGN OF
LANTHANIDE MAGNETOSTRICTIVE SONAR PROJECTORS)" P. 1059-1065 FIG. 2 is a schematic
cross-sectional view of an underwater wave transmitter using the conventional high
magnetostrictive rare earth alloy described in the above-mentioned document.
[0003]
This transmitter has a plurality of magnetostrictive rods 1 formed of a high magnetostrictive rare
earth alloy, and a coil 2 for generating magnetic bias or AC magnetic field is wound around the
magnetostrictive rods 1. There is. Disc-shaped vibrating bodies 4 are attached to both end faces
of the magnetostrictive rod 1 via the magnetic coupler 3 respectively. The vibrators 4 attached to
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both end surfaces of the magnetostrictive rod 1 are fixed by bolts 5 for applying prestress, and
apply prestress to the magnetostrictive rod 1 in the axial direction. In addition, a forced cooling
device 6 is attached to the outside of the coil 2, and the heat generated by the coil 2 is dissipated
to the outside.
[0004]
In this type of underwater wave transmitter, after being appropriately waterproofed, it is put in
water, and when an alternating current is passed through the coil 2, the magnetostrictive rod 1 is
moved in the axial direction (according to its magnitude) by the alternating magnetic field. It
expands and contracts in the longitudinal direction, and generates driving force in the axial
direction. The driving force is transmitted to the vibrating body 4 to vibrate the vibrating body 4,
generating a sound wave (such as an ultrasonic wave), and the sound wave is emitted into water.
[0005]
However, the apparatus having the above configuration has the following problems. The
magnetostrictive rod 1 formed using a high magnetostrictive rare earth alloy has a problem that
it is broken by mechanical force due to twisting or bending at the time of attachment to the
vibrator 4 or the like because the strength against lateral load is weak. . Moreover, when
prestressing the magnetostrictive rod 1 with the bolt 5, it is difficult to keep the joint surfaces of
the vibrating body 4 and the magnetostrictive rod 1 in parallel, and it is impossible to keep them
parallel. There is a problem that the force is concentrated on a part of the joint surface with the
magnetic coupler 3 and tipping is generated, and it is difficult to sufficiently protect the
magnetostrictive rod 1 there were.
[0006]
The present invention provides a protection mechanism of a high magnetostrictive rare earth
alloy, which solves the problem such as breakage or chipping of a magnetostrictive rod formed
using a high magnetostrictive rare earth alloy as a problem of the prior art. It is
[0007]
SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present
invention is formed using a high magnetostrictive rare earth alloy, and the magnetostriction is
expanded and contracted in the axial direction according to the magnitude of an alternating
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magnetic field acting from the outside. Actuator, transducer and the like provided with a rod, a
vibrating body attached to the end face of the magnetostrictive rod and vibrating due to the
strain of the magnetostrictive rod, and a prestressing means for applying a prestress in the axial
direction to the magnetostrictive rod The following measures are taken in such a drive device.
[0008]
That is, in the present invention, a bearing having a bearing surface in the direction parallel to
the magnetostrictive rod is provided with a pair or a plurality of pairs on the vibrator, and a
bearing is supported on the bearing surface slidably in parallel to the magnetostrictive rod. And
the high magnetostrictive rare earth alloy are protected.
[0009]
According to the present invention, since the protection mechanism of the high magnetostrictive
rare earth alloy is constituted as described above, the bearing having a bearing surface in the
direction parallel to the magnetostrictive rod and attached to the vibrator is It works to slidably
support the inserted shaft with a small clearance (gap).
Therefore, transmission of force is restricted only in the drive direction (axial direction) of the
magnetostrictive rod, transmission of force from other directions is excluded, and bending stress
and shear force acting as external force are not transmitted to the magnetostrictive rod.
Thereby, problems such as cutting and chipping of the magnetostrictive rod can be solved.
[0010]
1 (a) and 1 (b) are schematic structural views of an underwater wave transmitter showing an
embodiment of the present invention, and FIG. 1 (a) is a plan view and FIG. (B) is a sectional view.
This transmitter includes a magnetostrictive rod 10 formed of a supermagnetostrictive rare earth
alloy such as terbium dysprosium iron (TbDyFe). One or more magnetostrictive rods 10 are used
depending on the purpose of use, but FIG. 1 shows the case where one magnetostrictive rod 10 is
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used. A cylindrical bobbin 11 is disposed on the outer periphery of the magnetostrictive rod 10,
and a solenoid coil 12 for driving the magnetostrictive rod is wound around the bobbin 11.
[0011]
On both end surfaces of the magnetostrictive rod 10, disk-shaped vibrators 15 made of brass or
the like are attached via a magnetic coupler 13 for applying a magnetic bias to the
magnetostrictive rod 10 and a permanent magnet 14, respectively. There is. The diaphragms 15
on both sides are mutually connected by a plurality of shafts 16 which are pre-stress applying
means, and coil springs 17 provided at both ends of the respective shafts 16 and provided in the
respective diaphragms 15 On the other hand, prestress is applied in parallel in the axial direction.
The prestressing shaft 16 and the coil spring 17 are provided in two to five directions with
respect to one magnetostrictive rod 10. In FIG. 1, they are provided in three directions.
[0012]
Slide bearings 20 having bearing surfaces in the direction parallel to the magnetostrictive rods
10 are embedded in the diaphragms 15 on both sides respectively, and a shaft 21 for protecting
the magnetostrictive rods is inserted into the holes of the respective slide bearings 20. The
driving force is transmitted to the magnetostrictive rod 10 only in its axial direction. That is, the
shaft 21 is fixed to only one of the vibrating members 16 using the bolt 22, and the other end of
the magnetostrictive rod 10 is kept free (slidable), and stiffness against axial driving is obtained.
Does not work as a fixed state, but includes a component of resistance due to friction. This shaft
21 is also provided in two to five directions with respect to one magnetostrictive rod 10 as in the
prestress system. In FIG. 1, they are provided in three directions. In addition, the clearance
between the bearing surface of the slide shaft system 20 and the shaft 21 is set to about 10 μm
to 0.5 mm as a region that has low friction and satisfies the condition of axial restriction.
[0013]
In this type of underwater wave transmitter, after being appropriately waterproofed, it is put into
water. Since a magnetic bias is applied to the magnetostrictive rod 10 by the magnetic coupler
13 and the permanent magnet 14, when an alternating current is superimposed on the solenoid
coil 12, an alternating magnetic field is generated by the solenoid coil 12 and the
magnetostrictive rod 10 is in the axial direction Cause vibration of stretching. Then, due to this
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vibration, the vibrators 15 on both sides vibrate respectively, and sound waves (ultrasound etc.)
are generated and emitted into water.
[0014]
In the protection mechanism of the high magnetostrictive rare earth alloy in this underwater
wave transmitter, a slide bearing 20 is provided on each vibrating body 15, and one end of a
shaft 21 is slidably inserted in the slide bearing 20 with a small clearance. The other end of the
shaft 21 is fixed to one of the vibrators 15. Therefore, the other vibrating body 15 can slide only
in one axial direction parallel to the magnetostrictive rod 10 with respect to the shaft 21.
Therefore, when the magnetostrictive rod 10 is attached to the vibrating body 15 or the like,
when a mechanical force such as twist or bending is applied to the magnetostrictive rod 10, the
mechanical force is absorbed by the slide bearing 20 and the shaft 21, The magnetostrictive rod
10 is not applied. Therefore, it is possible to properly prevent the magnetostrictive rod 10 from
being broken by mechanical force. In addition, when the magnetostrictive rod 10 is prestressed
by the shaft 16 and the coil spring 17, the joint surface of the vibrating body 15 and the
magnetostrictive rod 10 can be kept parallel by the slide bearing 20 and the shaft 21. Chipping
can be precisely prevented.
[0015]
The present invention is not limited to the above embodiment, but various modifications are
possible. (A) In FIG. 1, the slide bearing 20 is used as a bearing, but the same operation and effect
as the above embodiment can be obtained even if other bearings such as oilless bearings (rolling
bearings) are used. (B) Although one end of the protective shaft 21 is fixed to the vibrating body
15 using the bolt 22, it may be fixed by another method using an adhesive or the like. (C) In FIG.
1, although the magnetic bias is applied to the magnetostrictive rod 10 using the permanent
magnet 14, the magnetic bias may be applied by another method.
[0016]
(D) In the above embodiment, the shaft 16 and the coil spring 17 constitute the prestressing
means, but the prestressing means may be constituted by another structure using an elastic body
or the like. . (E) In the above embodiment, although the underwater wave transmitter has been
described, if the driving device utilizes the vibrational force of the magnetostrictive rod, the
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protective mechanism of the magnetostrictive rod may be applied to various devices such as an
actuator. It is possible. The protection mechanism may be changed to another shape or structure
according to the structure or shape of the drive device.
[0017]
As described above in detail, according to the present invention, in the driving device using a
high magnetostrictive rare earth alloy, a bearing is provided on the vibrating body in order to
regulate the vibration in one axial direction, Since the shaft is slidably supported by the bearing,
power is transmitted smoothly only in one axial direction, bending stress and shear force acting
as external force are absorbed by the bearing and the shaft, and are not transmitted to the
magnetostrictive rod. Therefore, it is possible to accurately prevent the magnetostrictive rod
from being chipped or broken with a simple structure. Therefore, the present invention can be
applied to various driving devices such as an underwater transmitter.
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