WO2023182462A1

WO2023182462A1 - Magnetic marker

Info

Publication number: WO2023182462A1
Application number: PCT/JP2023/011654
Authority: WO
Inventors: 道治山本; 知彦長尾; 均青山
Original assignee: 愛知製鋼株式会社
Priority date: 2022-03-25
Filing date: 2023-03-23
Publication date: 2023-09-28
Also published as: JP2023142473A

Abstract

This magnetic marker (1) that is embedded in a road surface for use in vehicle driving assistance such as lane-associated autonomous steering or lane departure warnings is an assembly of a plurality of granular magnets (10) having a diameter of 1 mm. In the magnetic marker (1), adjacent magnets (10) among the plurality of magnets (10) are linked to one another using a foamed resin as a linking material. The magnetic marker (1) is provided with exceptional characteristics such that there is a possibility that a given extent of magnetic functionality can be maintained even when pavement is damaged, such as when potholes, which are holes in the road surface, are produced.

Description

magnetic marker

The present invention relates to magnetic markers placed on roads to assist vehicle driving.

Conventionally, magnetic marker systems for vehicles that utilize magnetic markers placed on roads have been known (for example, see Patent Document 1). Such magnetic marker systems are intended for vehicles equipped with magnetic sensors. When a vehicle detects magnetic markers placed along the lane, various types of driving support, such as automatic steering control and lane departure warning, are realized.

JP2019-214844A

However, when the road pavement deteriorates, the magnetic marker may fall off the road and the function of the magnetic marker may be lost all at once.

The present invention has been made in view of the above-mentioned conventional problems, and aims to provide a magnetic marker that has the possibility of maintaining its function even when pavement is damaged.

The present invention is a magnetic marker buried in a road surface for use in vehicle driving support,
The magnetic marker is an aggregate of a plurality of magnets, and the plurality of magnets are connected to form a column.

The magnetic marker of the present invention is an assembly in which a plurality of magnets are connected to form a column. This magnetic marker is divided into a plurality of parts and becomes easy to separate from each other because the connection between the magnets is impaired. For example, on a paved road surface, holes called potholes may occur as cracks in the road surface progress. For example, when a pothole near a magnetic marker gradually expands and the magnetic marker is exposed on its inner circumferential surface, if a portion can be separated as described above, there is a risk that the entire magnetic marker will immediately fall off the road. can be reduced. If even part of the magnetic marker remains on the road side, some of the magnetic functions of the magnetic marker can be maintained.

As described above, the magnetic marker of the present invention has an excellent property that it has the possibility of maintaining its magnetic performance to some extent even if damage occurs to the paved road surface.

FIG. 3 is an explanatory diagram showing magnetic markers placed on a road in Example 1. FIG. 1 is a sectional view showing a road pavement structure in Example 1. FIG. FIG. 2 is an explanatory diagram of the internal structure of a magnetic marker in Example 1. FIG. 7 is an explanatory diagram of the internal structure of a magnetic marker in Example 2. FIG. 3 is a cross-sectional view of a granular magnet in Example 2. FIG. 7 is an explanatory diagram of a guide member in Example 2. FIG. 7 is an explanatory diagram of the internal structure of a magnetic marker in Example 3. FIG. 7 is a perspective view showing a magnetic marker in Example 4. FIG. 8 is an explanatory diagram of the cross-sectional structure of the magnetic marker in Example 4 (view taken along the line AA in FIG. 8). FIG. 7 is an explanatory diagram of another magnet sheet in Example 4. FIG. 7 is an explanatory diagram of another method of joining magnet sheets in Example 4. FIG. 7 is a perspective view of a magnetic marker in Example 5. FIG. 7 is a perspective view of another magnetic marker in Example 5. FIG. 7 is a cross-sectional view of a magnetic marker in Example 6. FIG. 7 is a perspective view of a magnetic marker in Example 7. FIG. 7 is a perspective view of another magnetic marker in Example 7. FIG. 7 is an explanatory diagram of a marker bar in Example 8. FIG. 9 is an explanatory diagram showing how a magnetic marker is cut out from a marker rod in Example 8. FIG. 9 is an explanatory diagram of the state in which the tip of the marker rod is inserted into the accommodation hole in Example 8. FIG. 9 is an explanatory diagram of step 1 of separating the magnetic marker at the tip of the marker rod in Example 8. FIG. 7 is an explanatory diagram of the second procedure for separating the magnetic marker at the tip of the marker rod in Example 8. FIG. 9 is an explanatory diagram of the procedure for cutting off the magnetic marker at the tip of the marker rod and placing it in the accommodation hole in Example 8. FIG. 9 is a perspective view of a magnetic marker including a wireless tag in Example 9. FIG. 9 is a front view of the developed shape of the secondary antenna in Example 9.

(Example 1)
This example is an example of a magnetic marker 1 arranged on a road 3 so as to be detected by a magnetic sensor (not shown) attached to a vehicle. According to the magnetic marker 1, it is possible to support the driving operation of the vehicle by the driver or to control the vehicle to realize automatic driving that does not depend on the driver's operation. The contents will be explained with reference to FIGS. 1 to 3.

The magnetic marker 1 (FIG. 1) of this example is a buried type magnetic marker, and is installed (buried) in a state of being accommodated in a 30 mm deep accommodation hole 30 provided in the road surface 3S. The magnetic marker 1 has a columnar shape with a diameter of 30 mm and a height of 20 mm. Since the height of the magnetic marker 1 is 20 mm with respect to the depth of the accommodation hole 30 mm, the upper surface of the magnetic marker 1 placed in the accommodation hole 30 is set back about 10 mm from the road surface. After accommodating the magnetic marker 1, the accommodating hole 30 is filled with a polymeric material such as asphalt or a resin material. As a result, a lid 31 made of asphalt, resin material, or the like is formed on the upper surface side of the magnetic marker 1.

The cross-sectional structure (Fig. 2) of a road 3 paved with asphalt etc. roughly consists of a subgrade 3C made of compacted soil, a subgrade 3B made of granular materials such as crushed stone or crush run (an example of a base layer), and a heated asphalt mixture. It has a three-layer structure: a surface layer 3A. The heated asphalt mixture is an asphalt mixture in which coarse aggregate 331, fine aggregate 332, filler, and asphalt are mixed in a heated state. The layer thickness of the surface layer 3A is, for example, about 10 cm.

The coarse aggregate 331 is, for example, crushed stone with a particle size of 2.5 to 5 mm. Fine aggregate 332 is, for example, aggregate that passes through a 2.36 mm sieve and remains on a 0.075 mm sieve. The fine aggregate 332 is, for example, sand with a particle size of 0.075 to 2.36 mm. The filler, which is not shown, is a mineral powder that passes through a 0.075 mm sieve. The filler is, for example, stone powder made from powdered limestone.

The pavement of Road 3 inevitably suffers damage such as potholes as it ages. A pothole is a hole that occurs when a part of the surface layer 3A made of the heated asphalt mixture peels off from the road surface 3S. Potholes occur, for example, when the connection structure between the coarse aggregates 331 in the heated asphalt mixture forming the surface layer 3A is impaired.

The magnetic marker 1 (FIG. 3) is a substantially cylindrical molded product in which granular magnets 10 (hereinafter simply referred to as magnets 10) having a diameter of about 1 mm are dispersed in a molding material. That is, this magnetic marker 1 is an aggregate of a plurality of granular magnets 10, and the plurality of magnets 10 are connected so as to form a columnar shape as a whole using a molding material as a connecting material. As mentioned above, the outer dimensions of the magnetic marker 1 are 30 mm in diameter and 20 mm in height. The magnetic marker 1 is magnetized after molding, so that the direction of the magnetic pole of each magnet 10 is constant. Note that FIG. 3 is a perspective view showing a cross section including the central axis of the columnar magnetic marker 1.

The magnet 10 is an isotropic ferrite plastic magnet in which iron oxide magnetic powder, which is a magnetic material, is dispersed in a polymeric material that forms a base material. The polymer material is, for example, nylon 12. As the polymer material, in addition to nylon 12, for example, rubber, PPS (Poly Phenylene Sulfide), nylon 66, etc. may also be used.

This magnet 10 has a magnetic property of maximum energy product (BHmax)=12 kJ/m3. Isotropic ferrite plastic magnets, which are permanent magnets, are resistant to corrosion because their magnetic material is iron oxide. Therefore, the magnetic marker 1 including this magnet 10 is less likely to have a lower magnetic force due to corrosion, and can be directly accommodated in the accommodation hole 30 provided in the road surface 3S.

The molding material forming the magnetic marker 1 is polystyrene, which is an example of a resin material. The magnetic marker 1 is, for example, a molded article made of a material in which granular magnets 10 are mixed into a material obtained by primarily foaming raw material beads made of polystyrene and a hydrocarbon foaming agent. The magnetic marker 1 can be manufactured by filling a mold (not shown) with this material and molding it into a columnar shape. In the magnetic marker 1 of this example, an inter-magnet region 100 forming a gap between the granular magnets 10 is formed of styrene foam (foamed plastic, foamed resin), which is an example of a porous foam. That is, in the magnetic marker 1, adjacent granular magnets 10 are connected using expanded polystyrene as a connecting material. Styrofoam as a connecting material is less brittle than the magnet 10, which is an isotropic ferrite plastic magnet. When an excessive external force is applied to the magnetic marker 1, the styrene foam that is the connecting material breaks, and as a result, the magnetic marker 1 can separate into a plurality of small pieces and decompose.

The magnetic marker 1 of this example has magnetic properties such that the surface magnetic flux density is 45 mT (millitesla) and the magnetic flux density reaching a height of 250 mm is about 8 μT. Note that the height of 250 mm is an example of a height that corresponds to the upper limit of the expected range of mounting heights of the magnetic sensor in a vehicle.

One of the technical features of the magnetic marker 1 of this example is that the inter-magnet region 100 is a porous region formed of expanded polystyrene. Styrofoam has a lower breaking strength than paving materials and can break relatively easily. As described above, the magnetic marker 1 of this example has the characteristic that it is easily separated into small pieces when the polystyrene foam forming the inter-magnet region 100 between the granular magnets 10 breaks.

If the magnetic marker 1 exposed on the road surface 3S remains in one piece, the magnetic marker 1 will fall off the road as a whole due to the occurrence of potholes, and the magnetic function of the magnetic marker 1 will be lost all at once. It turns out. If the magnetic marker 1 of this example has a structure that can be separated into a plurality of small pieces, it is possible to separate a part according to the enlargement of a pothole or the like, and the remaining part may remain on the road side. Therefore, there is a high possibility that the magnetic marker 1 can maintain its magnetic function to some extent.

In this example, the magnetic marker 1 is illustrated in which granular magnets 10 each having a diameter of 1 mm are arranged in a dispersed manner. The size of the granular magnet 10 is preferably 0.2 mm or more and 3.0 mm or less. As the magnet 10, a spherical magnet with a diameter of 1 mm is exemplified, but it may also be a granular shape of a rectangular parallelepiped or a cube, or a granular shape having a plurality of protrusions, such as confetti. The size of the magnet 10 may vary. Furthermore, the magnet 10 may be in the form of powder or in the form of irregularly shaped pieces.

As the molding material, a resin material such as polyethylene, polypropylene, or polyurethane may be used instead of polystyrene in this example. As with the magnetic marker 1 of this example, the magnets 10 may be dispersed in a foamed resin (foamed body) made of these resin materials. For example, a polyurethane stock solution may be poured into a mold pre-filled with granular magnets 10 and foamed. Thereby, a magnetic marker in which the magnets 10 are dispersed in polyurethane foam, which is an example of a foam, can be obtained. Note that a degradable material may also be used as the resin material forming the foam.

The granular magnet 10 may be a ferrite rubber magnet or a sintered magnet instead of the isotropic ferrite plastic magnet of this example.
Note that in this example, a columnar magnetic marker with a circular cross section is exemplified. The cross-sectional shape is not limited to a circular shape. A columnar magnetic marker having a cross-sectional shape such as a triangular, square, or pentagonal shape may be used.

(Example 2)
This example is an example in which the manner in which the granular magnets 10 are gathered is changed based on the magnetic marker 1 of Example 1. The contents will be explained with reference to FIGS. 4 to 6.
The magnetic marker 1 of this example is an aggregate of granular magnets 10 with a diameter of 1 mm, as in Example 1 (FIG. 4). In this magnetic marker 1, the granular magnets 10 are bonded to each other at locations where they circumscribe each other, and a columnar outer shape is realized as a whole. Note that the broken line in FIG. 4 indicates a substantially cylindrical outer shape.

In this example, asphalt, which is a polymeric material, is used as the adhesive material for bonding the magnets 10 to each other. The adhesive material in the magnetic marker 1 is located in the gap between adjacent magnets 10 and serves as an example of a connecting material that connects the adjacent magnets 10. Asphalt as an adhesive material is arranged so as to cover the outer peripheral surface of the spherical granular magnets 10, but does not fill the gaps between adjacent granular magnets 10. As a result, an inter-magnet region 100 including holes 108 is formed between adjacent granular magnets 10 .

Here, an example of a method for manufacturing the magnetic marker 1 of this example will be shown. After filling a granular magnet 10 (FIG. 5) with a diameter of 1 mm with a coating layer 107 made of asphalt on the outer peripheral surface into a mold (not shown) having a space of 30 mm in diameter and 20 mm in depth, the asphalt is heated and softened. let The magnets 10 in the mold are bonded and joined by softened asphalt at their mutually circumscribing locations, thereby connecting them to form a columnar shape with a diameter of 30 mm and a height of 20 mm.

In the magnetic marker 1 of this example, the substantially spherical magnets 10 circumscribe each other, while gaps are created between adjacent magnets 10 to form holes 108. In this magnetic marker 1, the area where adjacent magnets 10 are in contact with each other and bonded together is small. Therefore, the magnetic marker 1 is easily broken and easily separated into small pieces.

Asphalt is also a road pavement material. In road pavements, the gaps between adjacent aggregates are filled with asphalt. On the other hand, in the magnetic marker 1 of this example, the gaps between the granular magnets 10 instead of aggregate are not filled with asphalt, and holes 108 are formed. Therefore, the magnetic marker 1 is less brittle and has lower breaking strength than pavement made of asphalt.

As the magnet 10, a granular magnet in which magnetic powder is dispersed in asphalt that forms the base material may be adopted. In this case, by heating the magnet 10, the outer periphery of the magnet 10 can be softened, thereby allowing adjacent magnets 10 to be bonded together.

It is also possible to prepare a bottomed cylindrical guide member 111 (FIG. 6), fill the inside of the guide member 111 with granular magnets 10, and then heat it. After the magnets 10 are bonded to each other by heating, the guide member 111 may be removed or may be used as a part of the magnetic marker 1 as it is.

In this example, asphalt is used as an adhesive material for bonding the magnets 10 together. Adhesive materials are not limited to asphalt. It is also good to use rubber, PPS (Poly Phenylene Sulfide), nylon 66, nylon 12, etc.
Note that the other configurations and effects are the same as in Example 1.

(Example 3)
This example is an example in which the molding material was changed based on the magnetic marker of Example 1. This content will be explained with reference to FIG.

This example is an example in which a degradable material that decomposes over time is used as the molding material for the magnetic marker 1. In this magnetic marker 1, an inter-magnet region 100 forming a gap between magnets 10 is filled with a degradable material. The inter-magnet region 100 is a region where the degradable material decomposes over time and pores and cracks can be formed. Naturally, if the molding material in the inter-magnet region 100 decomposes to form holes or cracks, the fracture strength of the magnetic marker 1 itself will decrease.

Examples of degradable materials that decompose over time include polymeric materials that decompose under the action of at least one of heat, light, and water, and biodegradable materials that decompose into low-molecular compounds due to the involvement of microorganisms in nature. materials, etc.

Further, as the molding material for the magnetic marker 1, it is also possible to use an adhesive material, an adhesive material, or the like, which has high strength initially, but whose strength gradually decreases due to changes over time.
Note that the adhesive material is an adhesive material in a narrow sense that is in a liquid state before use and becomes solid over time. The adhesive material is a semi-solid and viscous adhesive material that has both liquid and solid properties. It can also be considered that the concept of adhesive material in a broad sense includes adhesive materials and adhesive materials in a narrow sense.

As the adhesive material or adhesive material, for example, it is also possible to use an adhesive material that has relatively high strength immediately after bonding, but whose bonding strength gradually decreases due to changes over time. Further, for example, it is also possible to employ a disassembly adhesive material or a disassembly adhesive material that has some kind of disassembly factor and has the property that the bonding force decreases or the adhesive material peels off due to a disassembly operation that activates the disassembly factor.

If the bonding strength of the adhesive material, etc. in the inter-magnet region 100 is reduced, the bond between adjacent magnets 10 will become weaker, making it easier for cracks to occur.

For example, it may be an adhesive material that has a disassembly factor such as gas generation at the adhesive interface and loses its bonding strength by the disassembly operation of ultraviolet irradiation. This adhesive material is used, for example, as an adhesive material for ultraviolet release tape. Ultraviolet release tape is a tape called dicing tape in semiconductor processes. For example, it may be a water-absorbing resin-containing adhesive material that has a disassembly factor such as expansion of the water-absorbing resin and whose bonding strength is reduced by a disassembly operation such as immersion in water. For example, it may be a thermally expandable microcapsule-containing adhesive material that has a disintegration factor of microcapsule expansion and whose bonding strength is reduced by heating. For example, it may be a thermosetting/thermoplastic adhesive material that has disassembly factors such as softening and melting, and whose bonding strength is reduced by the disassembly operation of heating. For example, it may be an adhesive material that has a disassembly factor of embrittlement of the adhesive material and whose bonding strength decreases due to the embrittlement caused by heating or ultraviolet irradiation. For example, it may be a hydrolyzable adhesive material or adhesive material that has a disassembly factor called hydrolysis and whose bonding strength is reduced by the disassembly operation of supplying moisture. It may be a moisture-absorbing and peelable adhesive material that has disintegration factors such as moisture absorption and softening/melting of the adhesive material, and whose bonding strength decreases when immersed in hot water. For example, it may be an electromagnetic induction/thermoplastic adhesive material that has disintegration factors such as softening and melting, and whose bonding strength is reduced by electromagnetic induction heating. For example, it may be an easily peelable adhesive material that has a disassembly factor of mechanical fracture and whose bonding strength is reduced by a disassembly operation of applying a vertical load. For example, it may be an adhesive material that has a disassembly factor called mechanical destruction and whose bonding strength is reduced by the disassembly operation called action of shear load.

Furthermore, for example, a biodegradable material may be used as the molding material for the magnetic marker.
Further, for example, a biodegradable adhesive material or adhesive material may also be used. By using a biodegradable adhesive material that decomposes in nature, the bonding force can be gradually reduced after the magnetic marker 1 is embedded. Furthermore, if the adhesive material is biodegradable, the magnetic marker 1 can be easily disposed of, and the cost required for disposing of the magnetic marker 1 can be reduced.
Note that the other configurations and effects are the same as in Example 1.

(Example 4)
This example is an example in which the shape of the magnet constituting the magnetic marker 1 is changed based on the magnetic marker of Example 1. The outer shape and installation manner of the magnetic marker 1 are the same as in the first embodiment. The contents will be explained with reference to FIGS. 8 to 11.

The magnetic marker 1 of this example is the magnetic marker shown in FIGS. 8 and 9. FIG. 8 is a perspective view showing the appearance of the magnetic marker 1. FIG. 9 is a cross-sectional view showing the structure of a cross section including the central axis of the columnar shape. The cross section in this figure is taken along line AA in FIG.

The magnetic marker 1 (FIG. 8) of this example is a columnar magnetic marker in which disc-shaped magnet sheets (an example of magnet pieces) 11 each having a diameter of 30 mm are laminated using an adhesive material or an adhesive material. That is, the magnetic marker 1 of this example is an assembly of magnet sheets 11 that are disk-shaped permanent magnets. This magnetic marker 1 is a permanent magnet having a columnar outer shape with a diameter of 30 mm and a height of 20 mm, similar to the magnetic marker of Example 1. The magnet sheet 11 is a sheet-shaped isotropic ferrite rubber magnet in which iron oxide magnetic powder, which is a magnetic material, is dispersed in a polymeric material, which is a base material. Note that the magnetic performance of this magnetic marker 1 is almost the same as that of the magnetic marker of Example 1. Note that it is also good to laminate magnet sheets made of isotropic ferrite plastic magnets.

In the magnetic marker 1 (FIGS. 8 and 9), a bonding layer 12 made of an adhesive material or an adhesive material is formed in the gap between adjacent magnet sheets 11. For example, if an adhesive material or adhesive material that does not harden over time is used as the adhesive material or adhesive material, adjacent pieces can be easily separated via the bonding layer 12. Alternatively, it is also possible to use an adhesive material that hardens but easily causes the bonding layer 12 to break. If the bonding layer 12 breaks, cracks will occur between adjacent magnet sheets 11 and the bonding layer 12 will break, making it easy for the magnetic marker 1 to separate into a plurality of small pieces. As the adhesive material or adhesive material, the materials exemplified in Example 2 and Example 3 can be employed.

After accommodating the magnetic marker 1 in the accommodating hole 30 (see FIG. 1), if the accommodating hole 30 is filled with a polymeric material such as asphalt or a resin material, the shape of the magnetic marker 1 is maintained by the polymeric material. obtain. Therefore, even if the bonding force of the bonding layer 12 is lost over time, as long as the magnetic marker 1 remains in the accommodation hole 30, the magnetic marker 1 will not separate into a plurality of small pieces and will remain in an integrated state.

Incidentally, concave grooves 112 may be provided in a grid pattern on the surface of the magnet sheet 11 constituting the magnetic marker 1 in FIG. 8, as shown in FIG. 10. This magnet sheet 11 is easily divided into pieces because the concave grooves 112 serve as cuts. In addition to the bonding layer 12, the groove 112 of each magnet sheet piece serves as a cut in the magnetic marker in which the magnet sheets 11 are stacked, making it easy to separate into a plurality of small pieces. Furthermore, when stacking the magnet sheet pieces shown in FIG. 8, it is also possible to apply an adhesive material or the like only to the surfaces other than the concave grooves 112, or only to the concave grooves 112. In this case, the bonding area between adjacent magnet sheets 11 can be suppressed, and the bonding strength can be reduced.

As shown in FIG. 11, the adhesive material or the like may be applied only to the X-shaped region 113 indicated by dot hatching in the figure on the surface of the magnet sheet 11. In this case, by suppressing the bonding area between adjacent magnet sheet pieces, the magnetic marker 1 can be easily separated into a plurality of small pieces.

Furthermore, it is also possible to omit adhesive materials and the like. The stacked state of the magnetic markers 1 can be maintained by the magnetic attraction force generated between adjacent magnet sheets 11. The magnet sheet 11 constituting the magnetic marker 1 has a north pole on one side and a south pole on the other side. Adjacent magnet sheets 11 are laminated with the N-pole surface and the S-pole surface facing each other. Therefore, adjacent magnet sheets 11 are magnetically attracted to each other. A magnetic marker may be an assembly in which a plurality of magnet sheets 11 are magnetically connected to each other by the magnetic force of each magnet sheet 11, which is a permanent magnet.
Note that the other configurations and effects are the same as in Example 1.

(Example 5)
The magnetic marker 1 of this example is based on Example 4 and employs a guide member for maintaining the stacked state of the magnet sheets (an example of magnet pieces) 11. This content will be explained with reference to FIGS. 12 and 13.
In the magnetic marker 1 of FIG. 12, the stacked state of magnetic sheets 11 similar to the magnetic marker of Example 4 is held by a cylindrical guide member 115 extending in the axial direction (an example of a predetermined direction). It is. The guide member 115 is, for example, a sheet of paper, a metal foil such as aluminum foil, or a resin film wound into a cylindrical shape. The guide member 115 is preferably one that is easily torn to some extent rather than one that has high strength. When the guide member 115 breaks or breaks, the magnetic marker 1 becomes easily separated into a plurality of small pieces. Note that the two adjacent pieces of magnet sheets 11 in the magnetic marker 1 may be bonded to each other using an adhesive material with a weak bonding force, or may be attracted to each other only by the magnetic force of the magnet sheets 11. .

The cylindrical guide member 115 may be a molded layer formed on the outer peripheral surface of a columnar body on which the magnet sheets 11 are laminated. The mold layer is, for example, a layer made of a polymeric material such as asphalt or a resin material. Examples of the resin material include rubber, PPS (Poly Phenylene Sulfide), nylon 66, and nylon 12. Note that the magnet sheet 11 may be one illustrated in FIG. 10 . The guide member 115 may lose its shape by melting due to the action of moisture such as water or humidity or heat.

The mold layer, which is an example of the guide member 115, may be one that extends in the axial direction, as shown in FIG. 13, and does not necessarily have a cylindrical shape. As shown in the figure, strip-shaped mold layers 116 extending in the axial direction may be provided at multiple locations in the circumferential direction on the outer peripheral surface of the cylindrical magnetic marker 1. Such a mold layer 116 is effective in maintaining the laminated state of the magnet sheets 11. Instead of the mold layer 116 in FIG. 13, it is also possible to use a strip-shaped tape such as paper, metal foil such as aluminum foil, or resin film. It is preferable that the mold layer or tape be easily broken rather than having high strength. The mold layer 116 may lose its shape by melting due to the action of moisture such as water or moisture or heat.
Note that the other configurations and effects are the same as in Example 4.

(Example 6)
This example is an example of a magnetic marker based on Example 4, which employs a shaft-shaped guide member 117 for maintaining the stacked state of the magnet sheets (an example of magnet pieces) 11. The contents will be explained with reference to FIG. 14.

In the magnetic marker 1 shown in FIG. 14, a disc-shaped magnet sheet 11 with a small hole in the center is held by a rod-shaped guide member 117 extending in the axial direction (an example of a predetermined direction). be. The magnet sheet 11 is the same as the magnet sheet of the magnetic marker of Example 4 except for the small hole in the center. The rod-shaped guide member 117 may be, for example, a stick made of paper or wood, or a polymer material hardened into a rod shape.

The paper or wood rod used as the guide member 117 is preferably one that is easy to break, such as a thin rod or a rod with cuts at multiple locations in the axial direction. The rod made of a polymeric material may be a rod made of solidified asphalt, or a rod made of a resin material such as rubber, PPS (Poly Phenylene Sulfide), nylon 66, nylon 12, or the like. It is best to choose a material and thickness that is easy to break. The guide member 117 may lose its shape by melting due to moisture such as water or moisture or the action of heat.

Furthermore, the guide member 117 may be an elongated magnetic bar with magnetic poles disposed at both ends.
Note that the other configurations and effects are the same as in Example 4.

(Example 7)
The magnetic marker 1 of this example is a magnetic marker in which a plurality of columnar magnet pieces 13 having a fan-shaped cross section are combined to form a columnar shape similar to the other embodiments. The contents will be explained with reference to FIGS. 15 and 16.

In the magnetic marker 1 shown in FIG. 15, the magnet pieces 13 may be joined to each other using, for example, the adhesive material or adhesive material illustrated in Example 2 or Example 3, or a belt-like belt, string, etc. You may use it to bind. Alternatively, the cylindrical guide member illustrated in Example 5 may be used. The belt may be a ring of paper, metal foil, or resin film, or may be a molded layer made of a polymeric material. The string may be made of paper, metal, natural fiber, or chemical fiber, or may be a string-like string formed by printing a polymeric material on the outer peripheral surface.

For example, if a very thin iron belt or string is placed on a road, it can lose its binding function due to aging such as oxidation. Even if the binding function of the belt or string is lost, the columnar shape of the magnetic marker 1 can be maintained as long as it is accommodated in the accommodation hole 30 and the outer periphery is filled with asphalt or the like. Note that the members such as belts, strings, guide members, etc. that bind the columnar magnet pieces 13 with fan-shaped cross sections may lose their shape due to melting due to moisture such as water or moisture or heat. good.

Furthermore, as shown in FIG. 16, a magnet piece 131 may be employed in which a columnar body having a similar shape to the magnet piece 13 of FIG. 15 is divided into a plurality of pieces in the axial direction. The magnet piece 131 may be a fan-shaped thin magnetic sheet piece (an example of a magnet piece) like a piece of pizza. By stacking fan-shaped thin magnetic sheet pieces, a columnar body having a fan-shaped cross section can be formed. The magnetic marker 1 shown in FIG. 16 is a combination of these columnar bodies.

While an adhesive material or the like is used to form a columnar body with a fan-shaped cross section, when combining these columnar bodies to form the magnetic marker 1, it is also possible to bind them together with a belt, string, or cylindrical guide member. The columnar bodies may be joined together using a method such as the following. Alternatively, in forming the columnar bodies, the guide members such as mold layers and foils as exemplified in Example 5 may be used, while in combining the columnar bodies, the columnar bodies may be joined using an adhesive material or the like. It is also good to bind with belts, strings, or cylindrical guide members. The columnar body having a fan-shaped cross section may be formed by magnetically attracting fan-shaped magnetic sheet pieces like a piece of pizza to each other.

As described above, the magnetic marker 1 of this example is a magnetic component having a structure that can be separated into a plurality of small pieces. With this magnetic marker 1, when a pothole occurs due to damage to the pavement, it is possible to separate a portion according to the spread of the pothole. Therefore, even if a pothole occurs nearby, there is a high possibility that a part of the magnetic marker 1 will remain on the road side, and it is possible to maintain the magnetic function of the magnetic marker 1 to some extent. There is sex.

Further, the coarse aggregate 331 forming the surface layer of the pavement has a particle size of, for example, 2.5 to 5 mm, while the magnetic marker 1 has a diameter of 30 mm and a height of 20 mm. If the magnetic marker is integrated, there is a possibility that when a pothole occurs, the magnetic marker larger than the coarse aggregate 331 may roll out onto the road surface. On the other hand, if the magnetic marker 1 of this example has a structure that can be separated into a plurality of small pieces, there is little risk of it rolling out onto the road surface while remaining as one piece. Since this magnetic marker 1 can be separated into a plurality of small pieces, it only rolls out onto the road surface as small pieces that are the same size or smaller than the coarse aggregate 331.

In this example, a columnar magnetic marker with a circular cross section is illustrated. The cross-sectional shape is not limited to a circular shape. A columnar magnetic marker having a cross-sectional shape such as a triangular, square, or pentagonal shape may be used.
Note that the other configurations and effects are the same as in the other embodiments.

(Example 8)
This example is an example of an embodiment in which a plurality of magnetic markers can be handled integrally by utilizing a structure that can be separated into a plurality of small pieces. This example relates to a marker rod 1R in which a plurality of magnetic markers 1 of Example 1 are connected. This content will be explained using FIGS. 17 to 19(d).

The marker rod 1R (FIG. 17) has a connecting surface 100C that connects two magnetic markers 1 in the axial direction, and is composed of a plurality of magnetic markers 1 as a whole. The connection strength between the two magnetic markers 1 on the connection surface 100C is set to be smaller than the strength required to separate each magnetic marker 1 into small pieces.

For example, as shown in FIG. 18, if the marker rod 1R is placed on the workbench 105 so that the tip protrudes from the edge and a force in the orthogonal direction is applied to the tip, the connecting surface 100C becomes a cutting surface and the marker rod 1R The magnetic marker 1 can be cut out from. If the amount of protrusion of the tip from the edge of the worktable 105 is set to slightly exceed the height (total length) of the magnetic marker 1, the magnetic markers 1 can be efficiently cut out one by one.

It is also possible to use the marker rod 1R to accommodate the magnetic markers 1 one by one in the accommodation hole 30, as shown in FIGS. 19(a) to 19(d), for example. When the tip of the marker rod 1R is inserted, for example, about 13 to 18 mm (less than the height of the magnetic marker 1) into the accommodation hole 30 with a diameter of 38 mm and a depth of 30 mm (Fig. 19(a)), the marker rod 1R is inserted. By rotating the rear end side (FIG. 19(b)), one magnetic marker 1 can be easily separated (FIG. 19(c)). The magnetic marker 1 separated from the marker rod 1R in this manner falls to the bottom of the accommodation hole 30 due to its own weight and is accommodated (FIG. 19(d)).

For example, in the case of the magnetic marker of Example 1 or Example 2 (FIGS. 3 and 4), a horizontal hole or slit may be formed along the connecting surface 100C after producing a rod-shaped body. By using horizontal holes, slits, etc., the strength of the connecting surface 100C can be suppressed.

For example, in the case of the magnetic marker of Example 4 (FIG. 8), the amount of adhesive material applied on the connecting surface 100C is set to be lower than the amount of adhesive material applied for joining adjacent magnet sheets 11 in the magnetic marker 1. It is also good to have less. Alternatively, an adhesive material with lower bonding strength may be used as the adhesive material on the connecting surface 100C. By selecting the amount and type of adhesive material applied in this way, the strength of the connecting surface 100C can be suppressed.

For example, in the case of the magnetic marker of Example 5 (FIG. 12), it is preferable to employ a guide member to hold the entire marker rod 1R, while reducing the breaking strength of the guide member at a location corresponding to the connecting surface 100C. Various methods can be considered to reduce the breaking strength of the guide member, such as providing a cut in the guide member, reducing the thickness of the guide member, and the like. Furthermore, a low-strength connection structure may be provided at a location where a guide member corresponding to one of the adjacent magnetic markers 1 and a guide member corresponding to the other magnetic marker 1 are connected. .

Note that it is not an essential configuration to suppress the strength of the connecting surface 100C. It is preferable to use a jig or the like to cut out the magnetic markers 1 one by one from the marker rod 1R. By using a jig or the like, the magnetic marker 1 can be efficiently cut out from the marker rod 1R whose breaking strength in the axial direction is substantially constant.
Note that the other configurations and effects are the same as in the first embodiment.

(Example 9)
This example is an example in which a wireless tag 18 is added based on the magnetic markers of Examples 1 to 8. The contents will be explained with reference to FIGS. 20 and 21.
The magnetic marker 1 of this example (FIG. 20) is based on the magnetic marker of Example 1, with a wireless tag 18 attached to the end face. With respect to the end face of the magnetic marker 1 having a diameter of 30 mm, the wireless tag 18 has a cross-sectional shape of approximately 10 mm x 2 mm and a length of approximately 25 mm.

The wireless tag 18 is an electronic component in which an IC chip, an antenna for wireless communication, and the like are housed in a case made of a resin material or the like. The wireless tag 18 operates by external power supply using wireless radio waves, and wirelessly outputs pre-stored information. The information output by the wireless tag 18 is, for example, information such as location information and road type.

A secondary antenna 19 that amplifies radio waves transmitted and received by the wireless tag 18 is provided on the outer peripheral surface and end surface of the magnetic marker 1 of this example. The secondary antenna 19 is formed by printing conductive ink on the outer surface of the magnetic marker 1. The secondary antenna 19 has hook-shaped portions 194 bent at right angles at both ends, as shown in FIG. 21, which is shown unfolded on a plane. The hook-shaped portions 194 at both ends are bent opposite to the straight portion 191 in the middle. The straight portion 191 extends in the radial direction on the end surface, which is the mounting surface of the wireless tag 18, to reach the outer circumferential surface of the magnetic marker 1, and extends along the axial direction on the outer circumferential surface. The hook-shaped portion 194 is provided along the circumferential direction on the outer peripheral surface of the magnetic marker 1 .

In the magnetic marker 1 in FIG. 20, the wireless tag 18 is attached in contact with the straight portion 191 of the secondary antenna 19. Due to the electromagnetic coupling between the communication antenna built into the wireless tag 18 and the secondary antenna 19, the radio waves transmitted and received by the wireless tag 18 are amplified. The secondary antenna 19 may be an antenna made of copper foil, aluminum foil, or the like instead of a printed antenna made of conductive ink. If the antenna is made of metal foil, it should be sufficiently thin so that it does not interfere with the feature of the magnetic marker 1 that it can be separated into small pieces, or it can be easily peeled off from the outer peripheral surface of the magnetic marker 1. It is best to configure it like this.

Note that the secondary antenna 19 may also be used as a guide member that maintains the shape of the magnetic marker, which is an assembly of magnets. In this case, it is preferable that the straight portion 191 of the secondary antenna 19 be formed over the entire area in the axial direction on the outer peripheral surface of the magnetic marker 1.
Note that the other configurations and effects are the same as in the other embodiments.

Although specific examples of the present invention have been described above in detail as in the embodiments, these specific examples merely disclose an example of technology included in the scope of the claims. Needless to say, the scope of the claims should not be interpreted to be limited by the configurations, numerical values, etc. of the specific examples. The scope of the claims includes techniques in which the specific examples described above are variously modified, changed, or appropriately combined using known techniques and the knowledge of those skilled in the art.

1 Magnetic marker 10 Magnet 100 Area between magnets 108

Hole

111, 115, 117 Guide member 18 Wireless tag 19 Secondary antenna 3 Road

3A Surface layer

3S Road surface 30 Accommodation hole 331 Coarse aggregate 332 Fine aggregate

Claims

A magnetic marker buried in the road surface for use in vehicle driving support,
The magnetic marker is an aggregate of a plurality of magnets, and the plurality of magnets are connected to form a column.
In claim 1, the material located in the gap between adjacent magnets among the plurality of magnets is a connecting material that connects adjacent magnets among the plurality of magnets, and the connecting material is a connecting material that connects adjacent magnets among the plurality of magnets. A magnetic marker that is a less brittle material than each of the magnets.
3. The magnetic marker according to claim 2, wherein the connecting material is a foamed resin.
In any one of claims 1 to 3, the material located in the gap between adjacent magnets among the plurality of magnets is a connecting material that connects adjacent magnets among the plurality of magnets, and The connecting material is an adhesive material or an adhesive material,
The adhesive material or the adhesive material is a magnetic marker that is a disassembly adhesive material or a disassembly adhesive material whose bonding force is reduced by activating a disassembly factor through a predetermined disassembly operation.
In any one of claims 1 to 3, the material located in the gap between adjacent magnets among the plurality of magnets is a connecting material that connects adjacent magnets among the plurality of magnets, and The connecting material is a magnetic marker, which is a biodegradable material.
2. The magnetic marker according to claim 1, wherein the plurality of magnets are magnetically interconnected by the magnetic force of each magnet to form the aggregate.
The magnetic marker according to any one of claims 1 to 6, wherein the plurality of magnet pieces are held in a columnar state by a guide member extending in a predetermined direction.
8. The magnetic marker according to claim 7, wherein the guide member is a mold layer made of a polymeric material formed on the outer peripheral surface of a columnar magnetic marker.