A coil includes: a wound conducting wire; and a terminal structure formed on an end of the conducting wire. The conducting wire is formed by bundling and twisting a plurality of strands. The strands are arranged longitudinally along a central axis of the coil. A method for manufacturing the coil includes: causing the end to pass through an internal space; then inserting a partition plate into a sleeve in a longitudinal direction so as to push the strands apart and arranging the strands in a first region and a second region; and then pinching the sleeve in a lateral direction and crushing the sleeve.

CROSS-REFERENCE TO RELATED APPLICATION

Priority is claimed on Japanese Patent Application No. 2022-054187, filed on Mar. 29, 2022, the contents of which are incorporated herein by reference.

BACKGROUND

Field of the Invention

The present invention relates to a coil.

Background

In recent years, in order to enable more people to secure easy access to affordable, reliable, sustainable, and advanced energy, research and development have been conducted on charging and power supply in vehicles equipped with secondary batteries that contribute to energy efficiency.

Coils used in contactless power transmission systems are known (see, for example, Japanese Unexamined Patent Application, First Publication No. 2015-220357, Japanese Unexamined Patent Application, First Publication No. 2010-042690, and Japanese Unexamined Utility Model application, First Publication No. H06-050330).

SUMMARY

In technology relating to charging and power supply in vehicles equipped with secondary batteries, since known coils are made of litz wires, it is difficult to perform end processing for electrically connecting a plurality of strands that constitute the litz wires to terminals.

An object of an aspect of the present invention is to provide a coil that facilitates end processing. Further, the aspect of the present invention contributes to energy efficiency.

A coil according to a first aspect of the present invention includes: a wound conducting wire; and a terminal structure formed on an end of the conducting wire, wherein the conducting wire is formed by bundling and twisting a plurality of strands, and the strands are arranged longitudinally along a central axis of the coil.

According to this configuration, the conducting wire is formed by bundling and twisting the plurality of strands, and the strands are arranged longitudinally along the central axis of the coil. Thus, a part of an inner surface of a sleeve penetrates an insulating coating from both sides of the end that has passed through the sleeve and directly bites into the strands, so that the end and the sleeve can be electrically connected to each other. Accordingly, a terminal structure can be formed without requiring a release agent to permeate and melt the insulating coating of the strand in an inner layer inside an outer layer, or without requiring the end and the sleeve serving as a terminal to be electrically connected to each other via solder. Accordingly, it is possible to provide a coil that facilitates end processing.

In a second aspect, diameters of the strands may be at least 0.20 mm and at most 0.45 mm.

According to this configuration, the diameters of the strands are at least 0.20 mm and at most 0.45 mm Thus, the diameters of the strands can be made within twice the skin depth of the strand in a case in which a working frequency is at least 85 kHz, which is used in a contactless power receiving and supply system. Accordingly, even in a case in which the coil is used when the skin depth is small and at relatively high frequencies where conduction is difficult inside the conducting wire, the diameter of the strand can be increased to the extent that an influence of a skin effect can be inhibited. It is possible to reduce the number of rows of the strands arranged longitudinally in a cross-section of the conducting wire. It is possible to effectively reduce uneven distribution of current density inside the conducting wire due to the skin effect and a proximity effect, thereby inhibiting AC resistance.

In a third aspect, the strands may be arranged in three rows or less along the central axis of the coil.

According to this configuration, the strands are arranged in three rows or less along the central axis of the coil. Thus, at the end, the strands arranged in an internal space of the sleeve can be arranged in two rows by dividing each row by a partition plate. All strands constituting the cross-section of the conducting wire can be brought into contact with the inner surface of the sleeve. Accordingly, the terminal structure can be formed on the end without requiring a release agent, solder, or the like.

In a fourth aspect, an insulating coating of the strands may have a melting point exceeding the melting point of solder.

According to this configuration, the insulating coating of the strands has the melting point exceeding the melting point of the solder.

Thus, heat resistance of the strands and the conducting wire can be improved. Accordingly, the coil can be used for applications that require heat resistance and durability such as a contactless power receiving and supply system, where a high voltage of tens of thousands of volts or more normally acts on the coil.

In a fifth aspect, the terminal structure may include a sleeve having an internal space through which the end passes, a blade protruding inward from an inner surface of the sleeve, and a partition plate dividing the internal space into a first region and a second region, and the strands may be arranged in the first region and the second region.

According to this configuration, the terminal structure is configured to include a sleeve having an internal space through which the end passes, a blade protruding inward from the inner surface of the sleeve, and a partition plate dividing the internal space into the first region and the second region. In addition, the strands are arranged in the first region and the second region. Thus, the strand arranged in the first region is electrically connected to the sleeve through contact with the blade passing through the insulating coating while arranged longitudinally between the partition plate and the blade. Accordingly, the terminal structure can be formed on the end of the conducting wire without requiring processing using a release agent, solder, or the like.

A sixth aspect of the present invention is a coil manufacturing method for manufacturing the coil, the method including: causing the end to pass through the internal space; then inserting the partition plate into the sleeve in a longitudinal direction so as to push the strands apart and arranging the strands in the first region and the second region; and then pinching the sleeve in a lateral direction and crushing the sleeve.

According to this configuration, the method for manufacturing a coil includes: causing the end to pass through the internal space, then inserting the partition plate into the sleeve in the longitudinal direction so as to push the strands apart and arranging the strands in the first region and the second region, and then pinching the sleeve in the lateral direction and crushing the sleeve. Thus, the blade can be made to penetrate the insulating coating formed on the strand and come into contact with a conductor covered with the insulating coating of the strand. In each of the first region and the second region, the strands can be arranged in a row in the longitudinal direction without overlapping each other in the lateral direction. Accordingly, the blade can be brought into contact with the conductor covered with the insulating coating in all the strands at the end. Thus, electrical connection between the end and the sleeve can be ensured without requiring processing using a release agent, solder, or the like. In addition, it is possible to provide the coil that facilitates end processing.

A contactless power supply device according to a seventh aspect of the present invention includes the coil.

According to this configuration, the contactless power supply device includes the coil. Thus, it is possible to provide the contactless power supply device that facilitates end processing.

A contactless power receiving device according to an eighth aspect of the present invention includes the coil.

According to this configuration, the contactless power receiving device includes the coil. Thus, it is possible to provide the contactless power receiving device that facilitates end processing.

A contactless power receiving and supply system according to a ninth aspect of the present invention includes the contactless power supply device and the contactless power receiving device.

According to this configuration, the contactless power receiving and supply system includes the contactless power supply device and the contactless power receiving device. Thus, it is possible to provide the contactless power receiving and supply system that facilitates end processing.

According to the aspect of the present invention, it is possible to provide the coil that facilitates end processing.

DESCRIPTION OF EMBODIMENTS

Embodiment

A coil1according to an embodiment of the present invention will be described below with reference to the drawings.

FIG.1is a perspective view showing a contactless power supply device100or a contactless power receiving device200including the coil1according to the embodiment.FIG.2is a cross-sectional view along arrow A inFIG.1.FIG.3is a cross-sectional view along arrow C inFIG.1.FIG.4is an explanatory diagram for explaining an assembling state of a terminal structure20. In addition,FIG.2shows, as a representative, a cross-section of a conducting wire10for two turns, which is a cross-section of the conducting wire10of an n-th turn and the conducting wire10adjacent thereto.

Also, hereinafter, a direction along a central axis P of the coil1may be referred to as a longitudinal direction, and a direction perpendicular to the central axis P and perpendicular to an extending direction D of the conducting wire10may be referred to as a lateral direction B.

As shown inFIG.1, the contactless power supply device100or the contactless power receiving device200according to the embodiment includes the coil1wound around the central axis P. Thus, it is possible to provide the contactless power supply device100or the contactless power receiving device200that facilitates end processing.

The coil1may be used in the contactless power supply device100. The contactless power supply device100including the coil1may be provided near a road surface of a road.

The coil1may be used in the contactless power receiving device200. The contactless power receiving device200including the coil1may be provided at a bottom portion of a vehicle traveling on the road.

The contactless power supply device100and the contactless power receiving device200are provided in a contactless power receiving and supply system disposed in a positional relationship in which they can come close to each other and face each other. The coil1may be used in the contactless power supply device100. The coil1may be used in the contactless power receiving device200. The coil1may be used in both the contactless power supply device100and the contactless power receiving device200.

The contactless power receiving and supply system includes the contactless power supply device100including the coil1and the contactless power receiving device200including the coil1. The contactless power supply device100and the contactless power receiving device200including the coil1are disposed in a positional relationship in which they face each other at a distance within an influence of magnetic field resonance. Thus, electric power can be wirelessly transmitted from the contactless power supply device100to the contactless power receiving device200. In addition, it is possible to provide the contactless power receiving and supply system that facilitates end processing.

As shown inFIG.1, the coil1includes the wound conducting wire10and the terminal structure20formed at an end10E of the conducting wire10.

As shown inFIG.2, the conducting wire10is formed by bundling and twisting a plurality of strands10a. Also, here, 16 strands10aare arranged in three rows. In addition,FIG.2shows an arbitrary cross-section of the conducting wire10configured by twisting and bundling each of the strands10a. Accordingly, each of the strands10ais disposed at a different position depending on a cross-section thereof.

The coil1is obtained by winding the conducting wire10. The conducting wire10is wound around the central axis P. The conducting wire10is wound seven turns around the central axis P, for example.

A distance between adjacent conducting wires10(a distance between a center of the n-th turn conducting wire10and a center of the n+1-th turn conducting wire10) can be preferably about twice the width of the conducting wire10. Thus, alternating current resistance can be reduced, ensuring a space factor.

The coil1can be wound in a spiral shape, preferably along the same plane. Thus, a size of the coil1in a direction along the central axis P can be restrained. Electromagnetic compatibility and output can be ensured by inhibiting parasitic capacitance and leakage electromagnetic waves.

The coil1may be wound in a rectangular shape along the same plane. Thus, the output can be effectively ensured while the size of the coil in the direction along the central axis P is kept small. Long sides of the rectangular shape are disposed in a traveling direction of the vehicle on which the contactless power receiving device200is mounted, and thus even in a case in which a relative positional relationship between the coil1of the contactless power supply device100and the coil1of the opposing contactless power receiving device200deviates, as long a transmission time of the electric power as possible can be secured.

The conducting wire10is made of a conductive material such as copper, aluminum, clad steel, or the like.

The conducting wire10is a twisted wire obtained by twisting and bundling the plurality of strands10a.

As shown inFIG.2, the conducting wire10is disposed in a posture in which the longitudinal direction of the cross-section (arrangement of the strands10a) is aligned with the central axis P of the coil1. Thus, it is possible to increase the number of turns by disposing the adjacent conducting wires10at appropriate intervals while ensuring a cross-sectional area of the conducting wire10in accordance with the electric power supplied to the conducting wire10. Accordingly, it is possible to increase the output by increasing the space factor of the conductive wire and restrain the size of the coil in the direction along the central axis. In addition, a surface area of the conducting wire10can be increased, and cooling efficiency can be enhanced.

Here, as shown inFIG.2, the strands10aare arranged longitudinally along the central axis P of the coil1in a cross-sectional view perpendicular to the extending direction D of the conducting wire10. In other words, when the conducting wire10is viewed in a cross-section perpendicular to the extending direction D of the conducting wire10, a contour formed by the plurality of strands10ahas the maximum dimension in the longitudinal direction along the central axis P that is larger than the maximum dimension in the lateral direction B perpendicular to the central axis P. In this way, in the cross-section of the conducting wire10, the strands10aare arranged longitudinally along the central axis P of the coil1. Thus, a sleeve21is crushed (crimped) in the lateral direction, and a portion of an inner surface of the sleeve21penetrates insulating coatings from both sides of the end10E passed through the sleeve21and directly bites into the strands10a, and thus, the end10E and the sleeve21can be electrically connected to each other. Accordingly, the terminal structure20can be formed without requiring a release agent to be permeated in order to melt the insulation coatings of the strands10ain an inner layer inside an outer layer, or the end10E and the sleeve21serving as a terminal to be electrically connected to each other via solder.

Thus, the coil that facilitates end processing can be provided. In addition, since the width of the conducting wire10can be reduced, the conducting wire10can be tightly packed on the same plane and wound with a high space factor. Thus, outer dimensions of the coil1can be kept as small as possible while inner dimensions thereof can be made as large as possible. Accordingly, the coil1can be compact and have a high coupling coefficient. Further, in the cross-section of the conducting wire10, an area ratio of a group of the strands10ain the inner layer inside the outermost layer in the lateral direction B can be reduced, and thus it is possible to reduce uneven distribution of current density due to a proximity effect occurring between the adjacent strands10aand a skin effect occurring between the adjacent conducting wires10, thereby inhibiting AC resistance.

Each strand10ais covered with the insulating coating (not shown).

The insulating coating of the strand10ahave a melting point exceeding a melting point of solder. For example, the strand10ais covered with the insulating film made of a resin material having a melting point higher than that of solder (for example, a highly heat-resistant foam material such as PEEK or polyurethane). Thus, heat resistance of the strand10aand the conducting wire10can be improved. Accordingly, it can be used for applications requiring heat resistance and durability such as a contactless power receiving and supply system in which a high voltage of tens of thousands of volts or more normally acts on the coil1.

Diameters of the strands10aare preferably at least 0.20 mm and at most 0.45 mm. In this way, the diameters of the strands10aare set to at least 0.20 mm and at most 0.45 mm Thus, the diameters of the strands10acan be made within twice the skin depths δ of the strands10ain a case in which the frequency used is set to 85 kHz or higher, which is used in a contactless power receiving and supply system. Also, the skin depth δ may be a theoretical value calculated from an angular frequency of an AC current flowing through the conducting wire10, electrical conductivity of the conducting wire10, and magnetic permeability of the conducting wire10. Accordingly, even in a case in which the skin depth δ is small and it is used at a relatively high frequency at which electric conduction is difficult to be made inside the conducting wire10, the diameters of the strands10acan be increased to the extent that the influence of the skin effect can be inhibited. In the cross-section of the conducting wire10, the rows of the strands10aarranged longitudinally can be reduced. It is possible to effectively reduce uneven distribution of current density inside the conducting wire due to the skin effect and the proximity effect, and to inhibit AC resistance.

The strands10acan preferably be arranged in three rows or less along the central axis P of the coil1. Thus, as shown inFIG.3, at the end10E, the strands10adisposed in an internal space S of the sleeve21can be partitioned row by row by a partition plate22and arranged in two rows. All the strands10athat form the cross-section of the conducting wire10can be brought into contact with the inner surface of the sleeve21. Accordingly, the terminal structure20can be formed at the end10E without requiring a release agent, solder, or the like.

Also, the number of rows of the strands10amay be four or more. Even in a case in which the number of rows of the strands10ais four or more, if a thickness of the partition plate22is changed in accordance with the number of rows of the strands10a, the strands10aof the end10E can be disposed row by row.

As shown inFIG.3, the terminal structure20includes the sleeve21having the internal space S through which the end10E of the conducting wire10is passed, the partition plate22dividing the internal space S into a first region S1and a second region S2, and blades23protruding inward from the inner surface of the sleeve21. The strands10aof the end10E are divided and disposed in the first region S1and the second region S2.

In this way, the strands10aof the end10E are divided and disposed in the first region S1and the second region S2partitioned by the partition plate22. Thus, the strands10adisposed in the first region S1are electrically connected to the sleeve21through contact with the blades23penetrating the insulating coatings in a state in which they are disposed longitudinally between the partition plate22and the blades23. Thus, the terminal structure20can be formed at the end10E of the conducting wire10without requiring processing using a release agent, solder, or the like.

Also, the internal space S may be partitioned into a third region S3in addition to the first region S1and the second region S2by two or more partition plates22.

The sleeve21is a so-called crimp terminal. The sleeve21is made of a conductive material. The sleeve21may be formed by, for example, plating a base material made of brass, phosphor bronze, or the like with tin or the like as appropriate.

The sleeve21may be a cylindrical body of rotation or may have a quadrangular square tube shape.

The internal space S of the sleeve21has a cross-sectional shape larger than a cross-sectional shape of the end10E of the conducting wire10.

In a state before the sleeve21and the end10E are pressed, the first region S1of the sleeve21has a lateral width (a gap between the blade23and the partition plate22) exceeding the diameters of the strands10aand less than twice the diameters of the strands10a.

In a state before the sleeve21and the end10E are pressed, the second region S2of the sleeve21has a lateral width (a gap between the blade23and the partition plate22) exceeding the diameters of the strands10aand less than twice the diameters of the strands10a.

In a state before the sleeve21and the end10E are pressed, the internal space S of the sleeve21has a lateral width obtained by adding the lateral width of the first region S1, the lateral width of the second region S2, and a lateral width (a thickness) of the partition plate22.

In this way, the first region S1and the second region S2of the sleeve21each have the lateral width exceeding the diameters of the strands10aand less than twice the diameters of the strands10a. Thus, when the partition plate22is inserted into the sleeve21, the strands10aof the end10E in the internal space S are pushed into the first region S1and the second region S2, so that the strands10apushed into the first region S1and the second region S2can be arranged in a row. Each of the strands10aarranged in a row is pierced through the insulating coatings by the blades23on the inner surface of the sleeve21. Thus, the strands10aand the sleeve21can be reliably connected to each other simply by pressing the sleeve21toward the end10E without using a release agent, solder, or the like.

As shown inFIG.4, the sleeve21may optionally have a tongue piece25with an opening through which a bolt for connecting the terminal structure20to a terminal block (not shown) is passed. The tongue piece25extends along an axial center of the sleeve21.

The sleeve21has a slit26into which the partition plate22is inserted. The slit26is formed to extend linearly along the axial center of the sleeve21in a direction perpendicular to the axial center of the sleeve21(longitudinal direction) and perpendicular to the crimping direction (lateral direction B). Thus, the partition plate22can be inserted in the direction perpendicular to the crimping direction.

The partition plate22is a plate-like body. The partition plate22can preferably be made of a conductive material. The partition plate22can preferably be made of the same material as the sleeve21. The thickness of the partition plate22may be approximately the same as the diameters of the strands10a. The height of the partition plate22(a dimension in a direction in which it is inserted into the sleeve21) may be approximately the same as an inner dimension of the internal space S and may be approximately the same as an outer diameter of the sleeve21. The length of the partition plate22(a dimension along the axial center of the sleeve21) may be approximately the same as a length of the sleeve21(a dimension along the axial center of the sleeve21).

The partition plate22has a wedge-shaped tip22e. Thus, the strands10aof the end10E arranged in the internal space S can be easily pushed apart, and the partition plate22can be easily inserted into the internal space S of the sleeve21.

The blades23protrude inward from the inner surface of the sleeve21.

The blades23can preferably be made of a conductive material. The blades23can preferably be of the same material as the sleeve21.

Inner tips of the blades23are sharp so that they can shear and penetrate the insulating coatings.

The blades23extend in the direction perpendicular to the axial center of the sleeve21and perpendicular to the crimping direction (longitudinal direction). Also, the crimping direction is a lateral direction of the end10E which is longitudinally elongated. Thus, the blades23can be opposed to respective side surfaces of the strands10aarranged in a row. Accordingly, due to the crimping, the blades23can reliably penetrate the insulating coatings of the strands10a.

The blades23are provided in pairs at opposing positions on the inner surface of the sleeve21. Thus, when the sleeve21is crushed in the lateral direction, a shearing force acting on the strands10ain the first region S1from one of the paired blades23and a shearing force acting on the strands10ain the second region S2from the other of the paired blades23can be located on the same plane, and thus the shearing forces can be reliably applied to the insulating coatings of the strands10a. Also, the number of pairs of blades23is not limited to one. The pairs of blades23may be more than two pairs.

Next, a method for manufacturing the coil1will be described with reference toFIGS.4to8.

FIG.4is an explanatory diagram for explaining an assembling state of the terminal structure20.FIG.5is an explanatory diagram showing a state in which the partition plate22is inserted into the sleeve21.FIG.6is an explanatory diagram showing a state in which the strands10aare pushed apart by the partition plate22. FIG.7is an explanatory diagram showing a state in which the internal space S is divided by the partition plate22to separate the strands10a.FIG.8is an explanatory diagram showing a state in which the sleeve21is crushed from sides. Also,FIGS.5to8show a cross-section while the terminal structure20is assembled.

As shown inFIG.4, the terminal structure20of the coil1includes the sleeve21, the end10E of the conducting wire10inserted into the internal space S of the sleeve21, and the partition plate22. The terminal structure20of the coil1can be manufactured by crimping the sleeve21in a state in which the end10E is passed through the internal space S of the sleeve21.

Specifically, first, the end10E is passed through the internal space S.

After that, as shown inFIG.5, the partition plate22is in a posture oriented in the longitudinal direction with the tip22efacing the sleeve21. Then, as shown inFIG.6, the partition plate22is inserted into the slit26of the sleeve21in the longitudinal direction. Then, as shown inFIG.7, while the strands10aare pushed apart by the partition plate22, the tip22eof the partition plate22is brought close to or in contact with the inner surface of the sleeve21, and the partition plate22is moved to a position at which the internal space S can be partitioned. In this manner, the strands10aare arranged separately in the first region S1and the second region S2. Also, the partition plate22may be inserted from above or below the sleeve21.

After that, as shown inFIG.8, the sleeve21is pinched and crushed in the lateral direction. In this case, using an appropriate crimping tool, an appropriate amount of crimping (a crimp width) is controlled so that the blades23can reliably penetrate the insulating coatings and the conducting wire10is not cut.

As described above, the method for manufacturing the coil1is performed by inserting the end10E into the internal space S, then inserting the partition plate22into the sleeve21in the longitudinal direction to push the strands10aapart to be arranged into the first region S1and the second region S2, and then pinching and crushing the sleeve21in the lateral direction B.

Thus, the blades23can penetrate the insulating coatings formed on the strands10aand come into contact with the conductors covered with the insulating coatings of the strands10a. In each of the first region S1and the second region S2, the strands10acan be arranged in a row in the longitudinal direction without overlapping the strands10ain the lateral direction. Accordingly, the blades23can be brought into contact with the conductors covered with the insulating coatings in all the strands10a. Thus, electrical connection between the end10E and the sleeve21can be ensured without requiring processing using a release agent, solder, or the like. In addition, it is possible to provide the coil that facilitates end processing.

Further, the technical scope of the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the present invention.

In addition, it is possible to appropriately replace the constituent elements in the above-described embodiment with well-known constituent elements without departing from the scope of the present invention, and the modifications described above may be combined as appropriate.