JP2002164686A - Method and device for reed screen type magnetic shielding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and device for magnetic shielding with air permeability and see-through characteristic. SOLUTION: Finite-length magnetic bodies 6 are arrayed as a reed screen in a magnetic field. Here, the relationship between the cross-section area (Sa) of a gap G between adjoining magnetic bodies 6 and a product (Sm.μs) of the area (Sm) of lateral cross-section of the magnetic body 6 and a specific permeability μs of the magnetic body 6 is so selected that (Sm.μs)/Sa>1, attenuating the magnetic flux density between one side of the magnetic bodies 6 arrayed as a reed screen and the other side. The finite-length magnetic body 6 is preferred to comprise a grain oriented silicon steel plate or permalloy whose longitudinal permeability is higher than that lateral cross-section direction, with the length-direction being substantially parallel to the magnetic line direction of magnetic field. Further, the finite-length magnetic body 6 is strip-shaped with a square cross-section.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for intermittent magnetic shielding, and more particularly to a method and apparatus for intermittently using a group of finite-length magnetic materials in an interdigitated manner.

[0002]

2. Description of the Related Art With the advancement of technology, facilities using a large current are increasing. For example, in the train line 10 shown in FIG.
By increasing the number of vehicles per train and shortening the departure interval,
The current flowing through the forward cable 21 for feeding the feeder wire 11 and the trolley wire 12 of the line 10 and the current flowing through the return cable 22 connected to the rail 13 is large. There is also growing interest in the magnetic effect on the surroundings due to the increase in capacity of ultra-high voltage transmission lines. Furthermore, even inside a building, the magnetic influence on the surroundings by an NMR diagnostic apparatus and other devices using a large current has been studied.

Since an electric current generates a magnetic field around it, if there is an electronic device near a large current, its operation, for example, an electron flow in the device may be affected. In the illustrated example, in order to prevent the influence of the magnetic field around the line 10, the outward cable 21 and the backward cable 22 are housed in a magnetic shield duct 23 surrounded by a magnetic material plate such as an iron plate. If necessary, the feeder wire 11 is also stored in the magnetic shield duct 23. In the figure, reference numerals 14, 15,
16 and 17 show viaducts, substations, power supplies and trains, respectively.

[0004]

However, the conventional magnetic shield duct 23 made of an iron plate has no opening except for the cable penetrating portion, so that ventilation is poor, and the internal temperature is extremely high in summer due to direct sunlight. There is a problem. The high temperature inside the duct may cause insulation deterioration of the cable.

Accordingly, an object of the present invention is to provide a magnetic shielding method and apparatus having air permeability in order to solve the above problems.

[0006]

SUMMARY OF THE INVENTION The present inventor has noticed in an experiment using a magnetic shield plate that a magnetic shield effect is recognized not only on the surface of the magnetic shield plate but also in a certain range outside the periphery thereof. . First, the magnetic shield effect on the outer periphery of the magnetic shield plate will be described with reference to the experimental examples of FIGS.

[Experiment 1] FIG. 5 is a plan view of an experiment for confirming the magnetic shield effect on the outer periphery of one magnetic shield plate. In this experiment, length L = 4600 mm and width D = 3100
A current is passed through the horizontal coil 1 of mm and a distance S = 1550 from the conductor 1a inside the coil at the center of the conductor 1a on the long side.
A square oriented silicon steel plate 2 having a side length C = 910 mm was vertically set at a position of mm. The magnetic sensor 4 is placed on the measurement line 3 passing through the center in the longitudinal direction of the coil 1 at a distance X = 1540 mm from the coil conductor 1a. The magnetic flux density was measured while moving from one end in the vertical direction in parallel with the coil conductor 1a (in the Y-axis direction in FIG. 3A).

The graph of FIG. 6 shows the case where one magnetic shield plate 2 is used (curve β), the case where three magnetic shield plates 2 are superposed (curve γ), and the case where five magnetic shield plates 2 are superposed (curve δ). 6 shows an example of a magnetic flux density measurement result by the magnetic sensor 4. The horizontal axis of the graph indicates the distance from one end of the coil 1 in the length direction. In the same graph, the magnetic flux density when the magnetic shield plate 2 is not used (curve α) is also shown for comparison. From the graph, it can be seen that the magnetic shield effect is also recognized in a certain range outside the peripheral edge of the shield plate 2. As is clear from the graph, the shielding effect increases as the number of the shield plates 2 increases, but in the present experiment, the superposition of the five shield plates almost reached the saturation.

[Experiment 2] Further, the present inventor conducted an experiment for confirming the magnetic shielding effect when the magnetic shield plate has a gap. In this experiment, as shown in FIG.
Two magnetic shield plates 2 of 455 × 455 mm square made of iron plate were installed in parallel with the coil conductor 1a with an interval G in the horizontal direction. The same magnetic sensor 4 as in Experiment 1 was placed on the measurement line 3 at the center of both shield plates 2 at a distance X from the coil conductor 1a, and the magnetic flux density was measured while moving the magnetic sensor 4 in parallel with the coil conductor 1a.

FIG. 8 is a graph showing two magnetic shield plates 2.
An example of the results of magnetic flux density measurement by the magnetic sensor 4 when the gap G between them is 0, 50, 100, 200, and 455 mm is shown (curves β to の in the figure). The horizontal axis of the graph indicates the distance Y on a line passing through the origin and orthogonal to the measurement line 3 with the measurement point taken at the center of both shield plates 2 as the origin (see FIG. 7). Further, in the same graph, the magnetic flux density measurement result when one magnetic shield plate 2 is used is also shown for comparison (curve α).

As is clear from the graph of FIG. 1, even if an interval G equal to or less than the width of the shield plate 2 in a direction parallel to the coil conductor 1a is provided (curve ζ), the two magnetic shield plates 2 A considerable magnetic shielding effect was obtained in a portion including the portion behind the surface determined by the interval G and the outside of the peripheral edge thereof (hereinafter, may be referred to as a portion behind the two shield plates 2). When the gap G was less than half the width of the shield plate 2 (curve ε), an effect of reducing the magnetic flux density of about 10 μT was obtained in the area behind the two shield plates 2. When two shield plates 2 are brought into close contact with each other and the gap G between them is set to 0 mm (curve β), 900
The same shielding effect as a single × 455 mm rectangular shield plate was obtained.

As a result of performing the above experiment 2 on magnetic shield plates 2 of various shapes and materials, a plurality of magnetic shield plates 2 were arranged in parallel with the direction of the current to be magnetically shielded, and the distance G between adjacent shield plates 2 was set as follows. It has been found that a magnetic shield effect by a plurality of magnetic shield plates 2 can be obtained by selecting as follows. That is, the orthogonal space between the adjacent magnetic members 6 with respect to the product (Sm · μs) of the cross-sectional area (Sm) of the magnetic shield plate 2 and the relative magnetic permeability μs of the shield plate 2 in the direction orthogonal to the direction of the magnetic field to be shielded. Cross section of (Sa)
The shield plate 2 is arranged such that the magnetic flux density in the gap becomes significantly smaller than the magnetic flux density in the magnetic shield plate 2, specifically, (Sm · μs) / Sa> 1. Then, a magnetic shielding effect by the plurality of magnetic shielding plates 2 can be obtained. The present invention has been completed based on this finding. The interval between the adjacent shield plates 2 in the plurality of magnetic shield plates 2 does not need to be constant. Also, when the current is magnetically shielded, the angle between the surface of the magnetic shield plate 2 and the direction of the current to be shielded does not need to be limited to a right angle or a parallel angle, and may be any angle.

Referring to FIG. 1, in the interdigital magnetic shield method according to the present invention, a group of magnetic bodies 6 each having a finite length are arranged in an interdigital magnetic field, and the area (Sm) of the cross section of each magnetic body 6 is determined. ) And the relative permeability μs of the magnetic body (Sm · μs) to the ratio of the cross-sectional area (Sa) of the gap G (see FIG. 7) between the adjacent magnetic bodies 6 to (Sm · μs) / Sa> 1. The magnetic flux density is attenuated between the opposing surfaces of the group of magnetic members 6 arranged in an interdigitated manner.

Referring also to FIGS. 1 and 2, the intermittent magnetic shield device 8 according to the present invention includes a group of finite-length magnetic bodies 6 arranged in an interdigital manner in a magnetic field. The product of the area (Sm) and the relative permeability μs of the magnetic material (S
The ratio of the cross-sectional area (Sa) of the gap G between the adjacent magnetic bodies 6 (see FIG. 7) to (m · μs) is selected so as to satisfy (Sm · μs) / Sa> 1, and the group of magnetic bodies 6 arranged in an interdigital shape The magnetic flux density is attenuated between the opposing surfaces of. Reference numeral 7 in FIG.
Indicates a frame for fixing the magnetic bodies 6 arranged in a screen.
This frame 7 is not essential to the device of the present invention.

[0015]

1A, the magnetic shield plate 2 of FIGS. 5 and 7 made of a magnetic material having a relative magnetic permeability μs = 60,000 as a finite-length magnetic body 6 has a length C = 910 mm. ,
A rectangular magnetic body 5 having a rectangular cross section with a width of 20 mm and a thickness of 0.35 mm was used. In the figure, the short side (thickness direction) of the rectangular cross section is arranged parallel to the direction of the current of the current carrier 1. Further, an adjacent gap (hereinafter, sometimes referred to as a pitch) between the strip-shaped magnetic bodies 5 is set to 25 mm. The current in the horizontal coil conductor 1 was 50 amps. Hereinafter, the current carrier 1
A description will be given of a case where the coil conductor 1 is used as a magnetic field generating source hereinafter. However, the current carrier 1 is not limited to the coil conductor.

In order to confirm the magnetic shielding effect of the group of strip-shaped magnetic bodies 5 arranged as shown in FIG. 1A, as shown in FIG. 5, a gap S = 50 mm from the coil conductor 1a outside the central portion of the coil conductor 1a. A row of the strip-shaped magnetic bodies 5 was formed so that the center of the strip-shaped magnetic bodies 5 in the longitudinal direction was at the same height as the coil conductor 1a. The magnetic sensor 4 was placed on the measurement line 3 passing through the center in the length direction of the coil 1 at a distance X from the coil conductor 1a, and the magnetic flux density was measured while changing the distance X from the coil conductor 1a. An example of the measurement result by the magnetic sensor 4 is shown in the graph of FIG. Furthermore, a strip-shaped magnetic body 5
FIG. 3 shows the results obtained by measuring the shielding effect with the magnetic sensor 4 when the pitch was increased to 50, 100, 200, 400 and 800 mm.
Are shown together.

As can be seen from the graph of FIG. 3, when the strip-shaped magnetic bodies 5 are arranged at a pitch of 25 mm, the magnetic shield plate 2 of FIG. The same shielding effect was obtained. The graph of FIG. 3 is a measurement result when the height of the magnetic sensor 4 is set to the level of the coil conductor 1a (hereinafter, referred to as a coil level). As shown in FIG. Even when the height was changed, it was confirmed that a shielding effect substantially equivalent to that of the entire shield could be obtained at a point 500 mm or more away from the coil conductor 1.

From the graphs of FIGS. 3 and 4, it can be seen that, in the arrangement of the magnetic body group of FIG. 1A in which a gap is provided between adjacent strip-shaped magnetic bodies 5, the cross-sectional area Sm of the magnetic body in the direction perpendicular to the magnetic field caused by the current. (= 20 mm × 0.35 mm) and the relative permeability μs of the magnetic body 6 = 60
000 (Sm · μs), the magnetic flux density in the gap is reduced to about 25 mm × 20 mm by making the cross-sectional area Sa of the gap between the adjacent magnetic bodies 6 in the direction perpendicular to the magnetic field approximately equal to (25 mm × 20 mm). The magnetic flux density can be remarkably reduced as compared with the magnetic flux density in the middle, and it has been confirmed that a magnetic shield effect having substantially the same air permeability as the whole surface shield and air permeability can be obtained by the magnetic material group having a gap.

Moreover, according to the arrangement of the magnetic body 6 group shown in FIG. 1, it is sufficient to arrange the strip-shaped magnetic bodies 5 having a width of 20 mm at intervals of 25 mm as compared with the whole shield by the magnetic shield plate 2 of FIG. In order to obtain a shielding effect substantially equivalent to that of a full-screen shield, as a magnetic material, 20% (= {(25−2
0) / 25} × 100).

FIG. 2 shows, for example, a frame 7 surrounding a crossing line of a plane parallel to the direction of the current flowing through the current carrier 1 (see FIG. 1) and a row of planes at predetermined intervals perpendicular to the direction of the current. An example is shown in which a group of finite-length magnetic bodies 6, which are rod-shaped in this case, are attached to the frame body 7 along the crossing line.
Even when the rod-shaped finite-length magnetic body 6 of FIG. 2 is used, the product of the relative permeability μs of the finite-length magnetic body 6 and the cross-sectional area Sm (Sm · μs)
By adjusting the ratio of the cross-sectional area (Sa) of the gap between the adjacent magnetic bodies 6 with respect to the above, it is possible to obtain a shielding effect substantially equivalent to that of the whole-surface shield as in the case of FIGS. The present inventors have confirmed experimentally. That is, by arranging not only the strip-shaped magnetic body 5 but also the finite-length magnetic body 6 at the above-mentioned predetermined gap, the magnetic shielding effect provided with the air permeability and the see-through property by the space between the adjacent finite-length magnetic bodies 6 can be obtained. can get.

Thus, the provision of the "method and apparatus for air-permeable magnetic shielding" which is the object of the present invention is achieved.

[0022]

FIG. 1B shows a strip-shaped magnetic material 5 shown in FIG.
This is an embodiment in which a pair of 2 sheets is arranged at a pitch of 50 mm.
According to the magnetic body arrangement shown in FIG. 1B, the shielding effect near the current carrier 1 is inferior to the arrangement shown in FIG.
It was confirmed that a magnetic shielding effect similar to the arrangement of FIG. 1A can be obtained at a point 500 mm or more away from the current carrier 1. The ratio of the space cross-sectional area (Sa) between adjacent magnets to the value of the product of the cross-sectional area and the relative magnetic permeability (Sm · μs) in the set of two strip-shaped magnetic bodies 5 is 1 in FIG. It is considered that this is the same as the case where the strip-shaped magnetic bodies 5 are arranged one by one. The arrangement shown in FIG. 1B can create a larger gap than the arrangement shown in FIG. 1A, and thus can provide better air permeability and transparency.

In FIG. 1A, the short side (thickness direction) of the rectangular cross section of the strip-shaped magnetic body 5 is arranged (vertically) in parallel with the direction of the current, as shown in FIG. It is also possible to arrange the long side (width direction) of the rectangular cross section of the strip-shaped magnetic body 5 in parallel (horizontally) with the current carrier, that is, the coil conductor 1.
FIG. 10 shows a graph for comparing the magnetic shielding effect when the magnetic body 5 is placed vertically and horizontally. FIG.
From the graph of 0, it was confirmed that the vertical and horizontal installations exhibited substantially the same magnetic shielding effect. However, in the vicinity of the coil conductor 1, the horizontal magnetic shield performance is slightly superior. This is presumably because the interval between adjacent strip-shaped magnetic bodies 5 is smaller in the case of horizontal installation than in the case of vertical installation.

When the strip-shaped magnetic body 5 is used, the vertical or horizontal installation can be appropriately selected according to the conditions of the installation place. Preferably, every other strip-shaped magnetic body 5 is arranged horizontally or vertically with a rectangular cross section, and the other strip-shaped magnetic bodies 5
Are arranged vertically or horizontally, and the horizontally arranged magnetic bodies 5 and the vertically arranged magnetic bodies 5 are alternately arranged. By alternately disposing the horizontal and vertical arrangements, it is possible to adjust the air permeability and the transparency while maintaining the desired magnetic shield performance. It should be noted here that the orientation of each strip-shaped magnetic body 5 is not limited to the horizontal or vertical orientation described above, but may be at any angular position between the horizontal and vertical orientations. Further, the pitch of the plurality of strip-shaped magnetic bodies 5 is not necessarily required to be constant, and the interval between the adjacent strip-shaped magnetic bodies 5 differs depending on the position of the adjacent strip-shaped magnetic bodies 5 in the group of many magnetic bodies 5. Is also good.

Further, the present inventor has proposed that the finite-length magnetic body 6 used in the interdigital magnetic shield of the present invention be made of a directional magnetic material made of a directional silicon steel sheet or the like having a magnetic permeability in the longitudinal direction larger than the magnetic permeability in the cross-sectional direction. Was found to be suitable. In the embodiment of FIGS. 1 and 8, a strip-shaped magnetic body 5 made of a directional silicon steel sheet is used, and the magnetic permeability in the magnetic field direction can be increased as compared with that of a non-oriented silicon steel sheet. It was confirmed that it could be obtained. It was also confirmed that the same shielding effect was obtained for Permalloy and an equivalent magnetic material.

FIG. 12 shows various cross-sectional shapes of the finite magnetic body 6 used in the present invention. (A) in the figure is a cross-shaped cross section,
(B) is a Y-shaped cross section, (C) is a circular cross section, (D) is a hollow circular cross section, (E) is a square (rectangular) cross section, (F) is a hollow rectangular (rectangular) cross section, and (G) is a star. Shape section, (H) is H-shaped section, (I) is I-shaped section, (J) is T-shaped section, (K)
Is a semicircular cross section, (L) is a triangular cross section, (M) is a spiral cross section, (N) is a circular cross section having a multilayer space inside,
(O) shows rectangular cross sections each having a multilayer space inside. The intermittent magnetic shield method and apparatus of the present invention include:
The desired effect is exhibited by the finite length magnetic body 6 having any of the cross-sectional shapes shown in FIGS. Further, the cross-sectional shape of the finite-length magnetic body 6 in the present invention is not limited to the illustrated example.

FIG. 13 is a schematic view of the overall shape of a different embodiment of the strip-shaped magnetic body 6 of FIG. In the figure, (A) is a simple strip type, (B) is a middle swelling type, (C) is a perforated strip cut,
(D) is a needle type, (E) is a triangular type, (F) is a curved strip type,
(G) is a bent strip type, (H) is an angle member type, (I)
Indicates a twisted strip type, and (J) indicates a spiral type. FIG.
3 (K) shows a rotating trapezoidal finite length magnetic body, and (L) shows a finite length magnetic body having a different diameter rebar.

FIG. 14 is an explanatory view of a mode in which the finite-length magnetic bodies 6 of the interdigital arrangement according to the present invention are incorporated into a magnetic shield wall, a floor or a fitting. In the figure, (A) is a door incorporating a finite-length magnetic material, (B) is a partition panel incorporating a finite-length magnetic material, (C) is a ceiling hanging duct incorporating a finite-length magnetic material, (D) ) Is, for example, a display screen or display cover incorporating a finite-length magnetic material of an ultra-thin strip in an interdigital shape,
(E) shows window blinds each incorporating a finite-length magnetic body.

FIGS. 15A and 15B show various modes of the interdigital arrangement by the finite length magnetic body 6 of the present invention. FIG. 15B shows a magnetic shield of a wire pair by a row of perforated strip-shaped magnetic bodies, and FIG. 2
The magnetic shield which sandwiched the electric wire pair by the strip-shaped magnetic substance group of a row is shown. As shown in FIG. 3B, the finite length magnetic body is formed in a rectangular shape with a rectangular cross section, and a through hole is formed at a predetermined position of each finite length magnetic body. By aligning the body with the through hole and inserting the electric wire through the aligned through hole of the finite-length magnetic body, a magnetic shield device for the electric wire can be obtained.

FIG. 15A is a conceptual diagram of a magnetic shield type tent using a curtain member incorporating a finite length magnetic material. In order to make the magnetic shield type tent of FIG. A flexible curtain such as cloth, film, or paper in which a finite-length magnetic body for a shield device is interwoven or woven into an interdigitated shape.

FIG. 15D shows a magnetic shield in which an electric wire is passed through a hollow portion of a large number of hollow annular magnetic bodies, and a through hole is formed at the center of each finite length magnetic body in the group of finite length magnetic bodies. A rectangular magnetic plate was placed, and the rectangular magnetic plates were aligned with the through holes and arranged through the gap between the adjacent magnetic materials, and an electric wire was inserted into the through holes where the finite length magnetic material was aligned. Things. FIG. 7E shows a finite-length magnetic body 6.
FIG. 2D shows a cable covering or bellows, and magnetic plates having an annular cross section with a ring through hole formed in the center are arranged along the length direction of the cable as shown in FIG. FIG. 5F shows a magnetic shield of a cable duct formed by a row of a finite length magnetic body having both ends bent. The figure shows the cable
A long magnetic shield duct can be formed by showing one section of the duct and arranging this section along the length direction of the cable as shown in FIG.

FIG. 16 shows another embodiment of the interdigital arrangement of the strip-shaped magnetic bodies for the purpose of the magnetic shield. In the figure,
(A) is an arrangement in which two rows of strip-shaped magnetic bodies of the same shape arranged in parallel are interdigitated with each other in a comb shape, and (B) is a row of strip-shaped magnetic bodies having a wide width and a strip having a narrow width. An arrangement mode in which the rows of magnetic bodies are interdigitated with each other in a comb shape, (C) shows strip-shaped magnetic bodies of the same shape arranged in parallel like one row in which strip-shaped magnetic bodies of the same shape are arranged in parallel. An arrangement mode in which the other rows are adjacent to each other at right angles, (D) is an arrangement mode in which two rows of strip-shaped magnetic bodies of the same shape arranged in parallel on both sides of the flexible curtain are attached, respectively. E) shows an arrangement mode in which flexible curtains are attached to both side surfaces of a row of strip-shaped magnetic bodies of the same shape arranged in parallel.

FIG. 17 is an explanatory diagram of a method of forming a magnetic dark room (magnetic shield room) with a wall using a strip-shaped magnetic material. In the figure, (A) is a magnetic dark room having a peripheral wall in which rows of strip-shaped magnetic bodies of the same shape vertically arranged are provided outside, (B)
Is a magnetic dark room having a peripheral wall provided on the inner side and the outer side with rows of strip-shaped magnetic bodies of the same shape arranged vertically, and (C) shows the same as a row of strip-shaped magnetic bodies of the same shape arranged in parallel. A magnetic dark room in which other rows in which strip-shaped magnetic bodies of the same shape are arranged in parallel are attached to the inside and outside of the peripheral wall at right angles to each other, and (D) is a row of strip-shaped magnetic bodies of the same shape arranged horizontally. (E) shows a magnetic dark room having a peripheral wall provided outside, and (E) shows a magnetic dark room in which the entire peripheral wall is magnetically shielded by rows of strip-shaped magnetic bodies of the same shape arranged in parallel.

FIG. 17 (F) shows a flow path in which a plurality of vertical strip-shaped magnetic bodies are arranged so as to pass through the intersections of the horizontal orthogonal meshes at an interval from each other, and FIG. 17 (G) is along the center axis. The flow paths each having a plurality of strip-shaped magnetic bodies radially attached around the hollow portion at intervals from each other are shown.

The intermittent magnetic shield method of the present invention can be widely applied to civil engineering, construction and other technical fields. In the civil engineering field, when applying a magnetic shielding function to railway noise barriers, floor slabs, box culverts, formwork ribs, station buildings, feeder wire covers, etc., or when adding a magnetic shielding function to underground transmission lines such as common trenches, etc. It can be expected to be applied to
In the field of construction, for example, MRI and SQUA in hospitals
Magnetic shields (passive shields) for shielding disturbing magnetic fields into facilities such as IDs, EB devices and electron microscopes in semiconductor factories, electron microscopes and NMR in laboratories, and strong magnetic shields (eg, accelerators and nuclear fusion in laboratories). Magnetic shields (active shields) to prevent magnetic fields from leaking from magnetic fields facilities, motors and transformers in substations, electrical rooms in offices, and other facilities, and magnetic shield walls and slabs in computer rooms and electrical rooms in buildings It can be expected to be applied to such applications. It can be expected to be used as an equipment member such as a display cover, and can be expected to be applied to a hybrid type fitting such as a soundproof / magnetic shield wall combined with a sound absorbing material.

[0036]

As described in detail above, the intermittent magnetic shield method or apparatus according to the present invention has the following remarkable effects since a plurality of finite-length magnetic bodies are arranged in an interdigital manner at intervals. .

(A) A magnetic shield having good air permeability is provided.
It is possible to prevent deterioration of materials and equipment due to temperature rise. (B) The magnetic shield device can be made transparent so that maintenance and management of the magnetically shielded device can be facilitated. (C) A magnetic shield device in which a strip-shaped magnetic body is provided in a blind manner at a variable angle can realize a magnetic shield capable of adjusting air permeability and transparency. (D) It is possible to reduce the amount of the magnetic material corresponding to a predetermined interval provided between the finite-length magnetic bodies. (E) Economical design that optimizes the amount of material used according to the required shield level becomes possible.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of one embodiment of a magnetic shield method according to the present invention.

FIG. 2 is an explanatory diagram of one embodiment of the magnetic shield device of the present invention.

FIG. 3 is a graph showing a shielding effect of the present invention using a group of finite-length magnetic bodies having different pitches.

FIG. 4 is a graph showing the shielding effect of the present invention when the height of the magnetic sensor is changed.

FIG. 5 is an explanatory diagram of an experiment 1 for confirming a shielding effect of a peripheral edge of a magnetic shield plate.

FIG. 6 is an example of a graph showing the peripheral magnetic shield effect of FIG. 5;

FIG. 7 is an explanatory diagram of an experiment 2 for confirming a magnetic shielding effect of a magnetic shielding plate having a gap.

FIG. 8 is an example of a graph showing the magnetic shield effect of FIG. 7;

FIG. 9 is an explanatory view of an embodiment in which the long sides of the rectangular cross section of the strip-shaped magnetic body are arranged in parallel with the current.

FIG. 10 is an example of a graph showing the shielding effect of the embodiment of FIG. 9;

FIG. 11 is an explanatory diagram of a magnetic shield in a conventional train line.

FIG. 12 is a view showing various cross-sectional shapes of a finite-length magnetic body.

FIG. 13 is a view showing various three-dimensional shapes of a strip-shaped magnetic body.

FIG. 14 is an explanatory diagram of a mode in which a finite length magnetic body is incorporated into a wall, a floor, or a fitting.

FIG. 15 is an explanatory diagram of a magnetic shield for electric wires using a finite-length magnetic body.

FIG. 16 is a view showing various mounting modes of a strip-shaped magnetic body.

FIG. 17 is a diagram showing a wall surface of a magnetic dark room using a strip-shaped magnetic body.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Current carrier 2 ... Magnetic shield plate 3 ... Measurement line 4 ... Magnetic sensor 5 ... Strip magnetic body 6 ... Finite length magnetic body 7 ... Frame 8 ... Magnetic shield device 10 ... Train line 11 ... Feeding wire 12 ... Trolley wire 13 ... rail 14 ... viaduct 15 ... substation 16 ... power supply 17 ... train 21 ... outbound cable 22 ... return cable 23 ... magnetic shield duct.

Claims (15)

[Claims] 1. A group of finite-length magnetic bodies arranged in an interdigitated manner in a magnetic field, and a group (Sm · μs) of a cross-sectional area (Sm) of each magnetic body and a relative magnetic permeability μs of the magnetic body. The ratio of the cross-sectional area (Sa) of the gap between the adjacent magnetic bodies is selected so as to satisfy (Sm · μs) / Sa> 1, and the magnetic flux density attenuation occurs between the opposing surfaces of the group of magnetic bodies arranged in an interdigitated manner. Naruto blind magnetic shield method. 2. The method of claim 1, wherein the length direction of the finite length magnetic body is substantially parallel to the direction of the magnetic field lines of the magnetic field. 3. The shielding method according to claim 1, wherein
An interdigital magnetic shield method, wherein the finite-length magnetic body is made of a directional magnetic material having a magnetic permeability in a longitudinal direction greater than a magnetic permeability in a cross-sectional direction. 4. The method according to claim 1, wherein the finite-length magnetic body has a rectangular or circular rectangular cross section. 5. The shielding method according to claim 4, wherein one of two long and short sides of the rectangular cross section of the finite length magnetic body is:
A screen-type magnetic shield method in which the screen is inclined by a predetermined angle with respect to the direction in which the screens are arranged in a screen. 6. The shielding method according to claim 4, wherein one of two long and short sides of the rectangular cross section of the finite length magnetic body is:
An interdigitated magnetic shield method in which every other finite length magnetic body is parallel to the interdigitated direction and is perpendicular to the interdigitated direction for the remaining finite length magnetic substances. 7. A magnetic recording medium comprising a group of finite-length magnetic bodies arranged in an interdigitated manner, wherein a product (Sm · μs) of an area (Sm) of a cross section of each magnetic body and a relative magnetic permeability μs of the magnetic body. The ratio of the cross-sectional area (Sa) of the gap between adjacent magnetic materials to (Sm · μs) / Sa>
And a magnetic intermittent shield device which causes magnetic flux density attenuation between opposing surfaces of the interdigital magnetic body group when installed in a magnetic field. 8. The intermittent magnetic shield device according to claim 7, wherein said finite length magnetic body is made of a directional magnetic material having a magnetic permeability in a longitudinal direction larger than a magnetic permeability in a lateral direction. 9. The shield device according to claim 7, wherein
A screen-shaped magnetic shield device in which the finite-length magnetic body is formed in a rectangular shape with a rectangular cross section, and one of two long and short sides of the rectangular cross section is inclined at a predetermined angle with respect to the direction in which the screens are arranged in a screen. . 10. The shield device according to claim 7, wherein each of the finite-length magnetic members in the group of finite-length magnetic members is a rectangular magnetic plate having a through hole formed at the center thereof, and the rectangular magnetic plate is formed as a rectangular magnetic plate. An interdigitated magnetic shield device for an electric wire, wherein the electric wire is aligned in the through hole and arranged through the gap between the adjacent magnetic bodies, and the electric wire is inserted into the aligned through hole in the finite length magnetic body. 11. The group of finite-length magnetic bodies according to claim 7, wherein the finite-length magnetic bodies are formed in a rectangular shape with a rectangular cross section, and a through hole is formed at a predetermined position of each finite-length magnetic body. An interdigitated magnetic shield device for an electric wire, wherein each of the finite-length magnetic bodies in the medium is aligned with the through-hole, and the electric wire is inserted into the through-hole aligned with the finite-length magnetic body. 12. A shield device according to claim 7, wherein said group of finite-length magnetic bodies is formed by mutually interdigitating two rows of strip-shaped magnetic bodies of the same shape arranged in parallel. A blind-type magnetic shield device that can be used. 13. The shield device according to claim 7 or 8, wherein the group of finite-length magnetic bodies is formed of a strip-shaped magnetic body having the same shape in the same manner as one row in which strip-shaped magnetic bodies having the same shape are arranged in parallel. An interdigitated magnetic shield device formed by adjoining other parallel rows at right angles to each other. 14. The method according to claim 7, wherein the entire surface of each peripheral wall of the magnetic dark room is provided.
A magnetic dark room equipped with a magnetic shield device. 15. A row in which strip-shaped magnetic bodies of the same shape are arranged in parallel, and another row in which strip-shaped magnetic bodies of the same shape are arranged in parallel, on the entire surface of each peripheral wall of the magnetic dark room. 2. The group of finite-length magnetic bodies formed adjacent to each other at right angles to each other.
A magnetic dark room provided with the magnetic shield device of No. 3.