JPH1127967A - Driving of super magnetostrictive material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain very fine displacements in units of microseconds by forming a time lag in respective exciting coils for energizing them, so that a plurality of elastic waves based on magnetic strain generated by respective exciting coils overlap each other at one end surface of a magnetostrictive material. SOLUTION: The shape of a super magnetostrictive material 1 and exciting coils 2a, 2b are designated. A time lag is formed in only each of the exciting coils 2a, 2b so as to pass trigger pulse current and generate a displacement waveform at the end of the super magnetostrictive material 1. As a result, for example, pulse current is passed through the exciting coil 2a from the end of the super magnetostrictive material 1. When the pulse current is passed through the exciting coil 2b, after 12.4 μs the displacement of the displacement waveform of the end becomes one in which almost two displacements overlap each other, thus it is possible to attain very fine displacements in units of microseconds.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an application field of a displacement or a force for realizing a displacement of a unit of .mu.m in a microsecond or less, and more particularly to an application field of a micromachining, a high-precision high-speed positioning, a micropump and the like. Things.

[0002]

2. Description of the Related Art A phenomenon in which the dimensions change when a magnetic material is magnetized, that is, a "magnetostriction" phenomenon has been known for a long time. In recent years, however, a giant magnetostrictive material exhibiting unprecedented large magnetostriction has been discovered. The giant magnetostrictive material is a compound of a transition metal such as Fe, Ni, and Co and a rare earth metal such as terbium (Tb) and dysprosium (Dy), and shows a large magnetostriction even at room temperature.

[0003]

As a giant magnetostrictive material, for example, Terfenol-D (trade name) is generally available. And did not consider displacing the rod in microseconds (μs).

That is, considering the displacement in microseconds, even if the entire rod is displaced at the same time, the displacement of each part of the rod is the time required for the propagation of the elastic wave. Therefore, the conventional method described above cannot be said to be an effective displacement driving method of the rod made of the giant magnetostrictive material.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and has a plurality of exciting coils wound at different positions in the longitudinal direction of a bar-shaped giant magnetostrictive material. A method of driving a giant magnetostrictive material in which local magnetostriction is generated in the vicinity of each exciting coil of the giant magnetostrictive material by applying a current in the shape of the giant magnetostrictive material. It is an object of the present invention to provide a method of driving a giant magnetostrictive material in which the excitation coils are energized with a time difference so that a wave overlaps at one end face of the magnetostrictive material.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic circuit diagram of an electric circuit of a high-speed exciting coil driving device made of a giant magnetostrictive material. In the drawing, by inputting a trigger pulse, a single-shot substantially half-sine-wave current can be supplied to the exciting coil. In this experiment, it took about 5 minutes for the half-wave current to flow.
μs, that is, a frequency of about 100 KHz, so that the maximum value of the current can flow up to about 200 amperes.

In FIG. 2, the rod of the giant magnetostrictive material has a cylindrical shape with a diameter of 6 mm and a length of 60 mm, and an exciting coil for driving the rod has a diameter of 0.2 mm.
Wind a 4mm copper wire 17 times, inner diameter 6.5mm, outer diameter 10
mm and a length of 2.5 mm. Further, the position of the exciting coil was represented by a distance X from the axial end of the rod to the center of the coil. The displacement of the upper end of the rod was measured by an optical fiber type non-contact displacement meter.

First, in FIG. 2, when a distance x between the upper end of the giant magnetostrictive material and the center of the exciting coil is set to 30 mm, a pulse current of about 200 amperes and 5 μs is applied to the coil to generate magnetostriction. The displacement at the center of the upper end of the shaft was as shown in FIG. A search coil (not shown) is separately wound around the exciting coil to measure a voltage (electromotive force) induced by magnetic flux flowing through the exciting coil. In FIG. 3, the electromotive voltage is also superimposed on the time axis. Indicated.

Referring to the electromotive voltage data of the search coil shown in FIG. 3, a substantially half-sine-wave current flows through the exciting coil, and the flowing time is 4.8 μs. It turns out that the time until it becomes 2.2 μs. In FIG. 3, the value of 17.7 μs, which is the difference between the time when the current of the exciting coil becomes maximum and the time when the displacement of the shaft end of the giant magnetostrictive material becomes maximum, is the elastic wave due to the magnetostriction. From the surface to the end face of the giant magnetostrictive material, and the propagation speed of the elastic wave is about 1700 m /
s is calculated.

Next, under the above experimental conditions, the distribution of the approximate magnetic flux density inside the giant magnetostrictive material will be estimated. Now
The giant magnetostrictive material is an isotropic material, the BH curve is linear, the relative magnetic permeability is 10, the electric resistance is 6 × 10 −7 Ωm, and the exciting coil is 2
When the eddy current field analysis is performed on the assumption that a sine wave current of 100 KHz flows at 00 amps, the magnetic flux lines near the exciting coil are as shown in FIG. Note that the figure shows only one side half as an axisymmetric problem.

From the results of the experiment and analysis, it is understood that only the vicinity of the exciting coil contributes to the magnetostriction when high-speed pulse driving is performed.

Since it has been found that the local displacement caused by magnetostriction proceeds at about 1700 m / s as an elastic wave, a pulse current is supplied to each excitation coil by giving a time difference calculated from the interval between two excitation coils. Shed.

As shown in FIG. 5, the shapes and dimensions of the giant magnetostrictive material 1 and the exciting coils 2a and 2b are the same as those described above. One exciting coil 2a is located at a position 25 mm from the shaft end, and the other exciting coil 2b Was placed at a position 5 mm from the shaft end.
Also, the current flowing through each of the excitation coils 2a and 2b is
Same as above. First, FIGS. 6 (b) and 6 (d) show displacement waveforms of the giant magnetostrictive material shaft end when a pulse current is applied to only one excitation coil 2a and 2b, respectively. FIGS. 6A, 6C and 6E show the electromotive voltages of the search coils attached to the exciting coils 2a and 2b.

First, a pulse current is applied to the exciting coil 2a at a position 25 mm from the axial end of the giant magnetostrictive material 1, and 12.4 μs later, the exciting coil 2b at a position 5 mm away
Fig. 6 shows the displacement waveform of the shaft end when a pulse current is applied to the shaft.
(F). The displacement shown in FIG.
The displacements in (b) and (d) overlap.

As described above, the present invention has been described based on the embodiments. However, the present invention is not limited to the above-described embodiments, and may be implemented in any manner unless the configuration described in the claims is changed. it can. For example, in the above-described embodiment, the number of the excitation coils is two. However, if the number of the excitation coils is further increased, a larger displacement can be obtained.

[0016]

As described above, the method of driving a giant magnetostrictive material according to the present invention can obtain a minute displacement in a unit of microsecond with a simple structure, so that fine machining, precise high-speed positioning, and micro pumping can be performed. It can be used in various fields such as, for example, and has a great effect.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an electric circuit of a high-speed exciting coil driving device for giant magnetostrictive material according to the present invention.

FIG. 2 is a schematic view of a driving device for a giant magnetostrictive material.

FIG. 3 is a characteristic diagram showing displacement at a shaft end of a giant magnetostrictive material when a coil position X = 30 mm.

FIG. 4 is a conceptual diagram showing a state of a magnetic flux line when a coil position X = 30 mm.

FIG. 5 is a schematic view of a giant magnetostrictive material driving device according to an embodiment of the present invention.

FIGS. 6A to 6F are conceptual diagrams showing the principle of a driving device for a giant magnetostrictive material according to an embodiment of the present invention, and FIGS. 6A and 6C respectively show a coil position X = 25 mm;
And the electromotive voltage of the search coil when X = 5 mm,
(B) and (d) are displacements of the rod shaft end when the coil positions X = 25 mm and X = 5 mm, respectively, and (e) are searches when the exciting coils are simultaneously driven at the coil positions X = 25 mm and X = 5 mm. (F) is a characteristic diagram showing the displacement of the rod shaft end when the exciting coil is simultaneously driven at the coil positions X = 25 mm and X = 5 mm.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Giant magnetostrictive material 2a, 2b Excitation coil 3 Optical fiber type non-contact displacement meter

Claims (1)

[Claims] 1. A plurality of exciting coils of the above-mentioned exciting material are wound by changing a position of a plurality of exciting coils in the longitudinal direction of a bar-shaped giant magnetostrictive material, and applying a pulsed current to each of the exciting coils. A method of driving a giant magnetostrictive material that causes local magnetostriction in the vicinity thereof, wherein each of the excitations is performed so that a plurality of elastic waves based on magnetostriction generated by the excitation coils overlap on one end surface of the giant magnetostriction material. A method for driving a giant magnetostrictive material, wherein current is supplied with a time difference between coils.