Coil component, electric power sending device, electric power reception device, electric power transmission system, and method for transmitting electric power

Abstract

To cause a multilayered flat coil to function efficiently while suppressing increase of size and increase of weight.SOLUTION: A coil component 10 according to an embodiment includes: a first flat coil 11; a second flat coil 12 on the first flat coil 11; and a holding body 20 as a magnetic member, the holding body including a first layer part 21 covering a surface of the first flat coil 11 which is opposite to a surface facing the second flat coil 12. The first flat coil 11 and the second flat coil 12 are serially connected and the second flat coil 12 has a thickness of 0.01 mm to 0.025 mm, both inclusive.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a coil component, a power transmitting device, a power receiving device, a power transfer system, and a power transfer method. [Background technology]

[0002] 2. Description of the Related Art Wireless power transmission systems that transmit power in a non-contact manner are becoming more and more common.

[0003] For example, a system is known that transmits power in a non-contact manner by passing a high-frequency current through a resonant circuit including a coil.

[0004] When a high-frequency current is passed through a coil, a skin effect can occur. The skin effect increases AC resistance, which causes a decrease in transmission efficiency during power transmission. If the coil is made of Litz wire in consideration of this, the skin effect can be suppressed, and therefore the decrease in transmission efficiency can be suppressed. However, since Litz wire is formed by twisting together many enameled wires, the manufacturing costs are high and it takes a lot of effort to manufacture, and the larger the coil, the greater the manufacturing effort.

[0005] On the other hand, a technique is also known that employs a planar coil that is spirally shaped and plate-like, and has a rectangular conductor cross section (see Patent Document 1). Such a planar coil can be formed, for example, by punching out the coil from a plate material. Therefore, such a planar coil can improve manufacturing efficiency regardless of the size of the coil. It is also advantageous in terms of making the device into which the coil is incorporated thinner and lighter.

[0006] In a wireless power transmission system for an electric vehicle, a power transmitting device is installed on a road surface such as a parking lot, and a power receiving device is installed on the electric vehicle. For example, when the above-mentioned planar coil is used for an electric vehicle, the height dimensions of both the power transmitting device and the power receiving device can be suppressed. Therefore, the above-mentioned planar coil is useful in, for example, the vehicle field where space constraints are severe. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2020-47614 A Summary of the Invention [Problem to be solved by the invention]

[0008] The above-mentioned wireless power transmission system may be used in, for example, a drone, which is an unmanned flying object, or an underwater drone. In this case, a power receiving device including a coil is mounted on the moving object, but it is not desired that the weight and size of the moving object be significantly increased by mounting the power receiving device. Therefore, it is desirable that the power receiving device and its coil are lightweight and small in volume.

[0009] In addition, when contactless power transmission is applied to a drone, which is an unmanned flying object, the power transmission device may be installed in various locations such as high places and mountainous areas. In this case, if the power transmission device is heavy and large, the installation work is time-consuming. Therefore, it is desirable that the power transmission device and its coil are also lightweight and small in volume.

[0010] On the other hand, it is not desirable for the coil to be so miniaturized that its performance does not meet the desired specifications. In this regard, by stacking and connecting a plurality of the above-mentioned planar coils in series, it is possible to increase, for example, the inductance while suppressing the size increase.

[0011] The present inventors have found that in the above-mentioned configuration in which planar coils are multi-layered (hereinafter referred to as coil components), the coil performance (Q value, resistance, etc.) varies greatly depending on the relationship between the frequency of the supply current and the thickness of the planar coil. In particular, the present inventors have found that simply increasing the cross-sectional area of ​​the planar coil does not improve performance, and that using a planar coil with a small thickness, for example, can result in higher performance than using a planar coil with a large thickness.

[0012] As a result of intensive research based on the above findings, the inventors have found a configuration that allows a multi-layered planar coil to function efficiently while suppressing increases in size and weight by setting desirable dimensional conditions for the planar coil according to the frequency of use. In particular, the inventors have found a configuration that can function particularly well when applied to drones, which are relatively small unmanned aerial vehicles, and underwater drones.

[0013] The present disclosure has been made against the above background, and an object of the present disclosure is to provide a coil component, a power transmitting device, a power receiving device, a power transfer system, and a power transfer method that can enable a multi-layered planar coil to function efficiently while suppressing increases in size and weight. [Means for solving the problem]

[0014] The embodiments of the present disclosure relate to the following [1] to

[21] .

[0015] [1] A first planar coil; a second planar coil overlapping the first planar coil; a first layer covering a surface of the first planar coil opposite to a surface facing the second planar coil, the first layer including a magnetic member having magnetism; the first planar coil and the second planar coil are connected in series; A coil component, wherein the second planar coil has a thickness of 0.01 mm or more and 0.025 mm or less.

[0016] [2] The coil component according to [1], wherein the thickness of the first planar coil is 0.4 mm or more and 0.6 mm or less.

[0017] [3] The first planar coil comprises aluminum; The coil component according to [1] or [2], wherein the second planar coil contains copper.

[0018] [4] The magnetic member integrally holds the first planar coil and the second planar coil in a state where the first planar coil and the second planar coil overlap with a gap therebetween, The coil component according to any one of [1] to [3], wherein the magnetic member further includes a second layer portion covering a side surface of the first planar coil and a third layer portion filling the gap.

[0019] [5] The coil component according to any one of [1] to [4], wherein the magnetic member includes a wall portion protruding from the second planar coil.

[0020] [6] The coil component according to any one of [1] to [5], wherein the magnetic member includes a resin and magnetic particles held in the resin.

[0021] [7] The coil component according to any one of [1] to [6], wherein the magnetic member has a relative permeability of 5.0 or more.

[0022] [8] The coil component according to any one of [1] to [7], wherein the magnetic member is annular.

[0023] [9] A coil component described in any one of [1] to [8], further comprising a magnetic shielding member arranged to face the side of the first layer portion of the magnetic material opposite to the side facing the first planar coil.

[0024]

[10] The coil component according to [9], wherein the magnetic shielding member includes plate-shaped ferrite.

[0025]

[11] The coil component according to [9] or

[10] , wherein the magnetic shielding member has a relative permeability of 500 or more.

[0026]

[12] The first planar coil and the second planar coil each include a plurality of turns arranged in a radial direction, a distance in the radial direction from a center of the first planar coil to an inner circumferential surface of the turn portion of the first planar coil located at the innermost position in the radial direction is greater than a distance in the radial direction from an inner circumferential surface of the turn portion of the first planar coil located at the innermost position in the radial direction to an outer circumferential surface of the turn portion of the first planar coil located at the outermost position in the radial direction, 13. The coil component according to any one of claims 1 to 11, wherein a radial distance from a center of the second planar coil to an inner circumferential surface of the turn portion of the second planar coil that is located most inward in the radial direction is greater than a radial distance from an inner circumferential surface of the turn portion of the second planar coil that is located most inward in the radial direction to an outer circumferential surface of the turn portion of the first planar coil that is located most outward in the radial direction.

[0027]

[13] The first planar coil and the second planar coil each include an equal number of turns; 13. The coil component according to any one of claims 1 to 12, wherein the turn portions of the first planar coil and the second planar coil that are at the same position when counted from their respective centers at least partially overlap each other.

[0028]

[14] The coil component described in any one of [1] to

[13] , wherein the first planar coil and the second planar coil each include, as a plurality of turn portions, only a first turn portion and a second turn portion located radially outward from the first turn portion.

[0029]

[15] The coil component described in any one of [1] to

[14] , wherein the second planar coil includes a catalyst layer attached to the magnetic member and a plating layer laminated on the catalyst layer.

[0030]

[16] A first planar coil; a second planar coil overlapping the first planar coil; a member including a first layer portion covering a surface of the first planar coil opposite to a surface facing the second planar coil, the first planar coil and the second planar coil are connected in series; A coil component, wherein the second planar coil has a thickness of 0.01 mm or more and 0.025 mm or less.

[0031]

[17] A coil component described in any of [1] to

[16] , wherein the first planar coil and the second planar coil are supplied with an alternating current of 10 MHz or more, or are supplied with an alternating magnetic field of 10 MHz or more.

[0032]

[18] A coil component according to any one of [1] to

[16] , A power transmitting device comprising: a high-frequency current supply unit that supplies an alternating current of 10 MHz or more to the coil component.

[0033]

[19] A coil component according to any one of [1] to

[16] , A conversion unit that converts an AC current of 10 MHz or more generated by electromagnetic induction in the coil component into a DC current.

[0034]

[20] A power transmitting device and a power receiving device, A power transfer system, wherein at least one of the power transmitting device and the power receiving device is equipped with a coil component described in any one of [1] to

[17] .

[0035]

[21] A step of supplying an AC current of 10 MHz or more to a coil component in a power transmission device including the coil component according to any one of [1] to

[16] ; generating a current in a power receiving device based on a magnetic field generated in the power transmitting device, Effect of the Invention

[0036] According to the present disclosure, it is possible to make a multi-layered planar coil function efficiently while suppressing an increase in size and weight. [Brief description of the drawings]

[0037] [Figure 1] FIG. 1 is a diagram illustrating a schematic view of a wireless power transmission system to which coil components according to first to third embodiments are applied. [Diagram 2] FIG. 1 is a perspective view of a coil component according to a first embodiment. [Diagram 3] 3 is a cross-sectional view of the coil component taken along line III-III in FIG. 2. [Figure 4] FIG. 4 is an enlarged view of FIG. [Figure 5A] 5A to 5C are diagrams illustrating an example of a manufacturing method for the coil component according to the first embodiment. [Figure 5B] 5A to 5C are diagrams illustrating an example of a manufacturing method for the coil component according to the first embodiment. [Figure 5C] 5A to 5C are diagrams illustrating an example of a manufacturing method for the coil component according to the first embodiment. [Figure 5D] 5A to 5C are diagrams illustrating an example of a manufacturing method for the coil component according to the first embodiment. [Figure 5E] 5A to 5C are diagrams illustrating an example of a manufacturing method for the coil component according to the first embodiment. [Figure 6] FIG. 4 is a graph illustrating the relationship between the thickness of the planar coil and the Q value in the coil component according to the first embodiment. [Figure 7] FIG. 13 is a perspective view of a coil component according to a second embodiment. [Figure 8] 8 is a cross-sectional view of the coil component taken along line VII-VII in FIG. 7. [Figure 9] FIG. 11 is a graph illustrating the relationship between the thickness of the planar coil and the Q value in the coil component according to the second embodiment. [Figure 10] FIG. 13 is a perspective view of a coil component according to a third embodiment. [Figure 11] 11 is a cross-sectional view of the coil component taken along line XX in FIG. 10. [Figure 12] FIG. 11 is a graph illustrating the relationship between the thickness of the planar coil and the Q value in the coil component according to the third embodiment. [Figure 13] 1A to 1C are diagrams illustrating an example in which the coil components according to the first and third embodiments are applied to a power transmission system for a drone. [Figure 14] 1A to 1C are diagrams illustrating an example in which the coil components according to the first and third embodiments are applied to a power transmission system for a drone. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] Each embodiment will be described below with reference to the drawings.

[0039] In this specification, the terms "sheet," "film," "plate," and the like are not distinguished from one another solely on the basis of differences in name. Thus, for example, "sheet" is a concept that includes members that may also be called films or plates.

[0040] Fig. 1 shows a schematic diagram of a wireless power transmission system S to which a coil component 10 according to a first embodiment is applied. First, the wireless power transmission system S (hereinafter, abbreviated as power transmission system S) will be described with reference to Fig. 1. It goes without saying that coil components according to embodiments different from the first embodiment can be applied to the power transmission system S. Also, a combination of coil components according to different embodiments can be applied to the power transmission system S.

[0041] <Wireless power transmission system> The power transfer system S includes a power transmitting device 1 and a power receiving device 2. The power transmitting device 1 includes a coil component 10 and a high-frequency current supplying unit 1A. The coil component 10 in the power transmitting device 1 functions as a power transmitting coil. The high-frequency current supplying unit 1A supplies a high-frequency current to the coil component 10 serving as a power transmitting coil.

[0042] The power receiving device 2 includes a coil component 10 and a conversion unit 2A. The coil component 10 in the power receiving device 2 functions as a power receiving coil. The conversion unit 2A shapes a high-frequency current generated in the coil component 10. The conversion unit 2A has a rectifier circuit that converts the high-frequency current into a direct current, and the like. The conversion unit 2A may be configured to include, for example, a full-wave rectifier circuit including a plurality of diodes and a smoothing capacitor.

[0043] In this embodiment, each of the power transmitting device 1 and the power receiving device 2 includes a coil component 10. However, the coil component 10 may be used in only one of the power transmitting device 1 and the power receiving device 2, and a different type of coil component may be used in the other.

[0044] When transmitting power wirelessly (contactlessly) from the power transmitting device 1 to the power receiving device 2, the power transmitting device 1 supplies a high-frequency current of a predetermined frequency from the high-frequency current supply unit 1A to the coil component 10 serving as a power transmitting coil. At this time, a magnetic field is generated in the coil component 10 by electromagnetic induction. Then, due to the influence of this magnetic field, a high-frequency current is generated in the coil component 10 serving as a power receiving coil in the power receiving device 2. That is, the power receiving device 2 receives the magnetic field or is influenced by the magnetic field in the power transmitting device 1, and causes the high-frequency current to flow by electromagnetic induction. The conversion unit 2A converts this high-frequency current into a direct current, and supplies the converted direct current to, for example, a battery not shown.

[0045] As an example, the coil component 10 according to the embodiment described below is manufactured so that its performance is improved when it is supplied with an AC current of 500 KHz or more and 15 MHz or less, or when it is supplied with an AC magnetic field of 500 KHz or more and 15 MHz or less. Therefore, the high-frequency current supply unit 1A may supply an AC current of 500 KHz or more and 15 MHz or less, for example, so as to correspond to an AC current desired for the coil component 10. Also, the conversion unit 2A may convert an AC current of 500 KHz or more and 15 MHz or less, which is generated by electromagnetic induction when an AC magnetic field is supplied, into a DC current.

[0046] 1 employs a magnetic resonance method as a power transmission method. However, the coil component 10 according to the present embodiment may be used in a power transmission system that employs an electromagnetic induction method.

[0047] The use of the power transmission system S is not particularly limited, and the power transmission system S may be used, for example, in an electric vehicle, a drone, a robot, an underwater submersible or exploration robot in the sea, or an underwater drone. The use of the coil component 10 is not limited to a wireless power transmission system. For example, the coil component 10 may be used in a transformer, a DC-DC converter, an antenna, or the like.

[0048] <Coil parts> The following describes the coil device 10. Fig. 2 is a perspective view of the coil device 10. Fig. 3 is a cross-sectional view of the coil device 10 taken along line III-III in Fig. 2.

[0049] As shown in Figures 2 and 3, coil device 10 includes a first planar coil 11, a second planar coil 12, a holder 20 corresponding to a magnetic member, a first magnetic shield member 30, a second magnetic shield member 40, a first connection terminal 51, and a second connection terminal 52.

[0050] First planar coil 11 and second planar coil 12 are connected in series and overlap with a gap therebetween. Holding body 20 holds first planar coil 11 so as to maintain a state in which first planar coil 11 and first magnetic shield member 30 are separated from each other. Holding body 20 includes a portion (first layer portion 21 shown in FIG. 3 ) that covers the surface of first planar coil 11 opposite to the surface facing second planar coil 12. Holding body 20 holds first planar coil 11 and second planar coil 12 so as to maintain a state in which first planar coil 11 and second planar coil 12 are separated from each other.

[0051] The first magnetic shield member 30 is disposed so as to face a surface of the holder 20 (more precisely, the first layer 21 as the covering portion of the holder 20) opposite to the surface facing the first planar coil 11. In other words, the first magnetic shield member 30 also includes a portion covering the surface of the first planar coil 11 opposite to the surface facing the second planar coil 12. In detail, the first magnetic shield member 30 includes a portion covering the surface of the first planar coil 11 opposite to the surface facing the second planar coil 12 via the first layer 21 of the holder 20. The second magnetic shield member 40 also includes a portion covering the surface of the first magnetic shield member 30 opposite to the surface facing the first planar coil 11. In this embodiment, the second magnetic shield member 40 is in contact with the first magnetic shield member 30, but the second magnetic shield member 40 may be separated from the first magnetic shield member 30.

[0052] (First planar coil and second planar coil) First planar coil 11 has a spiral shape and is made of a conductive material. In the present embodiment, first planar coil 11 includes aluminum. Specifically, first planar coil 11 is made of aluminum.

[0053] In this embodiment, aluminum is used as the material of first planar coil 11 in order to reduce the weight and cost of coil component 10. As will be described later, in this embodiment, second planar coil 12 is made of copper. That is, in this embodiment, weight reduction is achieved by selecting a material for first planar coil 11 whose specific gravity is smaller than that of second planar coil 12. The material for first planar coil 11 may be, for example, an aluminum alloy. The conductivity of aluminum and aluminum alloys is smaller than that of copper. However, aluminum and aluminum alloys have a small specific gravity and are inexpensive. Therefore, when aluminum and aluminum alloys are used, if the requirements for coil performance such as transmission performance are not excessively high, a coil component with desired performance can be obtained rationally while suppressing weight increase and cost. As will be described later, the material for second planar coil 12 is not limited to copper, and may be aluminum or an aluminum alloy as long as the desired performance is obtained.

[0054] First planar coil 11 has a plate shape, and as shown in FIG. 3, first planar coil 11 has a rectangular cross-sectional shape in a direction perpendicular to the direction in which first planar coil 11 winds around in a spiral shape.

[0055] 2 and 3 indicates a first central axis of first planar coil 11 that passes through the center of the spiral shape of first planar coil 11. Hereinafter, the axial direction of first planar coil 11 refers to a direction extending on first central axis C1 or a direction parallel to first central axis C1. In addition, a direction perpendicular to first central axis C1 is referred to as a radial direction of first planar coil 11.

[0056] The first planar coil 11 has a conductor 11E having a spiral shape formed by a plurality of turn portions 11n. The plurality of turn portions 11n of the first planar coil 11 are arranged in a radial direction perpendicular to a first central axis C1 of the spiral shape. More specifically, the plurality of turn portions 11n are connected so as to gradually move away from the first central axis C1 of the spiral shape toward the radially outward direction. This forms the spiral shape.

[0057] The turn portion 11n is basically a shape in which a linear conductor portion does not form a ring but goes around the first central axis C1 360 degrees. In the case of a so-called planar coil, both ends of the turn portion 11n are shifted in the radial direction. In the case of a plurality of turn portions 11n, a radially outer end of one turn portion 11n is connected to a radially inner end of another turn portion 11n, and the other turn portions 11n extend away from the first central axis C1.

[0058] Hereinafter, the turn portion 11n closest to the first central axis C1 may be referred to as the turn portion 111. Also, the turn portion connected to the turn portion 111 may be referred to as the turn portion 112. In this embodiment, the turn portions 11n are composed of two turn portions 111-112. More specifically, the first planar coil 11 includes only the first turn portion 111 and the second turn portion 112 located radially outward from the first turn portion 111. Hereinafter, when describing matters common to each of the turn portions 11n, they will basically be referred to as the turn portion 11n.

[0059] In this embodiment, turn portion 11n winds around to form a circular shape. However, turn portion 11n may also wind around to form a rectangular shape. Note that the spiral shape referred to in this specification and disclosure means a planar curved shape wound in a helical shape. In other words, the spiral shape is a shape that winds around first central axis C1 of first planar coil 11 so as to be gradually positioned outward.

[0060] A radially inner end (end close to the first central axis C1) of the turn portion 111 closest to the first central axis C1 is electrically connected to the second planar coil 12. The connection wiring portion 14 shown in FIG. 2 is a conductor and electrically connects the turn portion 111 and the second planar coil 12 in series. The connection wiring portion 14 shown in the figure is formed integrally with the second planar coil 12 as an example, but may be formed integrally with the first planar coil 11. The connection wiring portion 14 may be connected to the first planar coil 11 by ultrasonic connection or the like. On the other hand, a radially outer end (end away from the first central axis C1) of the turn portion 112 farthest from the first central axis C1 among the multiple turn portions 11n is connected to a first connection terminal 51 (see FIG. 2).

[0061] Here, the radially inward direction of first planar coil 11 (turn portion 11n) means a direction approaching first central axis C1 in the radial direction. Moreover, the radially outward direction of first planar coil 11 (turn portion 11n) means a direction moving away from first central axis C1 in the radial direction. Moreover, in this embodiment, first central axis C1 is determined as follows. First, linear virtual turn portions having a shape similar to that of innermost turn portion 111 are drawn inward in the radial direction in sequence from the radially inner end of innermost turn portion 111 so as to form a spiral shape. Then, drawing is continued until a virtual turn portion that fits within a diameter of 1 cm can be drawn. Then, a line that passes through a radially inner region of the virtual turn portion that fits within a diameter of 1 cm in a direction perpendicular to the circumferential and radial directions of the spiral shape is determined as first central axis C1.

[0062] In the present embodiment, first planar coil 11 is formed by punching out an aluminum plate into a spiral shape, for example. The thickness of first planar coil 11 (thickness of conductor 11E) may be, for example, 0.1 mm or more and 1.0 mm or less. Coil component 10 provides or receives a magnetic field from the side not covered by first magnetic shield member 30 and second magnetic shield member 40. According to the knowledge of the present inventors, good coil performance can be obtained when the thickness of the coil closest to first magnetic shield member 30 is relatively large. From this viewpoint, the thickness of first planar coil 11 may be 0.4 mm or more and 1.0 mm or less. In particular, from the viewpoint of weight reduction, the thickness of first planar coil 11 may be 0.4 mm or more and 0.6 mm or less, 0.45 mm or more and 0.55 mm or less, or 0.5 mm or less. In addition, the radius of first planar coil 11 (the distance from first central axis C1 to the part farthest from it in the radial direction) may be 80 mm or more, or 80 mm or more and 450 mm or less.

[0063] Furthermore, the line width of first planar coil 11 (line width of conductor 11E), i.e., the radial width of each turn portion 11n (width in the radial direction), is not particularly limited. For example, the radial width of turn portion 11n may be 2 mm or more and 20 mm or less, 2 mm or more and 16 mm or less, 2 mm or more and 12 mm or less, or 2 mm or more and 8 mm or less. Although the number of turns of first planar coil 11 is 2 in this embodiment, it may be 3 or more.

[0064] In addition, in this embodiment, the inner space of first planar coil 11 is large. For more details, referring to FIG. 2, a radial distance D1 from the center of first planar coil 11 to an inner circumferential surface of first turn portion 111 of first planar coil 11 located radially inward is larger than a radial distance D2 from the inner circumferential surface of first turn portion 111 to an outer circumferential surface of second turn portion 112 of first planar coil 11 located radially outward. Distance D1 is preferably at least twice distance D2. However, the shape of such first planar coil 11 is not particularly limited.

[0065] Next, second planar coil 12 also has a spiral shape, and in this embodiment, second planar coil 12 contains copper. The material of second planar coil 12 is not particularly limited, but may be a material having a specific gravity greater than that of first planar coil 11, for example, a copper alloy. The material of second planar coil 12 may also be aluminum or an aluminum alloy. Second planar coil 12 also has a plate shape, and as shown in FIG. 3, the cross-sectional shape of second planar coil 12 in a direction perpendicular to the direction in which second planar coil 12 winds around in a spiral shape is rectangular.

[0066] 2 and 3 indicates a second central axis of second planar coil 12 that passes through the center of the spiral shape of second planar coil 12. Hereinafter, the axial direction of second planar coil 12 refers to a direction extending on second central axis C2 or a direction parallel to second central axis C2. In addition, a direction perpendicular to second central axis C2 is referred to as a radial direction of second planar coil 12.

[0067] In the present embodiment, second planar coil 12 is arranged to be coaxial with first planar coil 11. That is, first central axis C1 of first planar coil 11 and second central axis C2 of second planar coil 12 coincide with each other, in other words, they are located on the same straight line. However, first planar coil 11 and second planar coil 12 may overlap with each other such that first central axis C1 of first planar coil 11 and second central axis C2 of second planar coil 12 are parallel to each other. That is, first planar coil 11 and second planar coil 12 do not have to be coaxial.

[0068] Second planar coil 12 also has conductor 12E having a spiral shape with multiple turn portions 12n. Multiple turn portions 12n of second planar coil 12 are arranged in a direction perpendicular to second central axis C2 of the spiral shape.

[0069] The connection manner of the plurality of turn portions 12n and the names (such as turn portion 121) according to the positions are the same as those of turn portion 11n of first planar coil 11. In the present embodiment, the number of turns of first planar coil 11 and the number of turns of second planar coil 12 are the same, and the plurality of turn portions 12n are configured of two turn portions 121-122. That is, second planar coil 12 includes only first turn portion 121 and second turn portion 122 located radially outward from first turn portion 121. Also, turn portion 12n winds around to form a circular shape like turn portion 11n. Note that turn portion 12n may have a shape winding around to form a rectangular shape. Also, the number of turns of first planar coil 11 and the number of turns of second planar coil 12 may be different. Note that in second planar coil 12, turn portion 12n is entirely located on holding body 20. The first turn portion 121 has a shape that goes around the second central axis C2 by 360 degrees, and both ends are shifted in the radial direction. On the other hand, the second turn portion 122 does not go around the second central axis C2 by 360 degrees, and both ends are not shifted in the radial direction. However, the shape of the turn portion 12n is not particularly limited.

[0070] 3 and 4, in the present embodiment, any one of a plurality of turn portions 11n of first planar coil 11 and any one of a plurality of turn portions 12n of second planar coil 12 partially overlap in the axial direction of first planar coil 11. A part of turn portion 11n of first planar coil 11 and a part of turn portion 12n of second planar coil 12 that overlap in the axial direction of first planar coil 11 extend parallel to each other with their respective winding directions aligned. The state in which the winding directions are aligned means that the winding directions of first planar coil 11 and second planar coil 12 do not intersect at a point but overlap a certain distance on the same line.

[0071] In the present embodiment, turn portion 11n of first planar coil 11 and turn portion 12n of second planar coil 12 that are located at the same position when counted from their respective centers at least partially overlap. More specifically, first turn portion 111 of first planar coil 11 and first turn portion 121 of second planar coil 12 overlap with each other in the axial direction. Second turn portion 112 of first planar coil 11 and second turn portion 122 of second planar coil 12 overlap with each other in the axial direction.

[0072] The length of a portion of turn portions 11n of first planar coil 11 and the length of a portion of turn portions 12n of second planar coil 12, which overlap and extend parallel to each other as described above, may be ½ or more, or ¾ or more, of their respective total lengths. The present inventors have found that the greater the proportion of overlap between first planar coil 11 and second planar coil 12 extending parallel to each other, the more eddy current loss can be suppressed.

[0073] As described above, the radially inner end of turn portion 111 closest to first central axis C1 is electrically connected to second planar coil 12. More specifically, the radially inner end of turn portion 111 is connected to an inner end of turn portion 121 in second planar coil 12 via connection wiring portion 14. Here, when first planar coil 11 and second planar coil 12 are connected, the direction in which first planar coil 11 winds from an end not connected to second planar coil 12 (a radially outer end of turn portion 112) to an end connected to second planar coil 12 becomes the same as the direction in which second planar coil 12 winds from an end connected to first planar coil 11 to an end not connected to first planar coil 11 (a radially outer end of turn portion 122).

[0074] Moreover, the radially outer end of turn portion 122, which is farthest from second central axis C2, among the multiple turn portions 12n, is connected to second connection terminal 52. The radially inner and outer directions of second planar coil 12 (turn portion 12n) are defined in the same manner as the radially inner and outer directions of first planar coil 11 described above. The position of second central axis C2 is also determined in the same manner as the first central axis C1.

[0075] In the present embodiment, the thickness of first planar coil 11 (the thickness of conductor 11E) is greater than the thickness of second planar coil 12. In other words, the thickness of second planar coil 12 (the thickness of conductor 12E) is smaller than the thickness of first planar coil 11. The thickness of second planar coil 12 is not less than 0.01 mm and not more than 0.025 mm.

[0076] In this embodiment, since the thickness of the second planar coil 12 is very small as described above, the second planar coil 12 is formed by electroless plating, electrolytic plating, PVD, or CVD. More specifically, the second planar coil 12 in this embodiment is formed by electroless copper plating. Therefore, as shown in FIG. 4, the second planar coil 12 includes a catalyst layer 12X attached to the holder 20 and a plating layer 12Y laminated on the catalyst layer 12X. The catalyst layer 12X includes a catalyst metal, which may be palladium. The plating layer 12Y includes copper. Note that, when the second planar coil 12 is formed by electrolytic plating, PVD, or CVD, etching is required, but when electroless copper plating is used, the etching step can be omitted. Therefore, the second planar coil 12 can be formed efficiently.

[0077] The present inventors have found that when first planar coil 11 and second planar coil 12 are stacked on first magnetic shield member 30 and holding body 20 (specifically, first layer 21 thereof) or on holding body 20 (specifically, first layer 21 thereof), the performance of coil component 10 when used in a predetermined frequency band can be ensured while suppressing an increase in size and weight by setting the thickness of second planar coil 12 to 0.01 mm or more and 0.025 mm or less as described above. For this reason, the thickness of second planar coil 12 is set to 0.01 mm or more and 0.025 mm or less. The predetermined frequency band is the frequency band of the AC current to be passed, and specifically, is 500 KHz or more and 15 MHz or less. That is, coil component 10 according to the present embodiment is configured to ensure good performance while suppressing an increase in size and weight when the frequency band of the AC current to be passed is 500 KHz or more and 15 MHz or less. This will be described in detail later.

[0078] The radius of second planar coil 12 (the distance from second central axis C2 to the part farthest in the radial direction) may be 80 mm or more, or may be 80 mm or more and 450 mm or less, as in the case of first planar coil 11. In addition, the line width of second planar coil 12 (the line width of conductor 12E), i.e., the radial width of each turn portion 12n (the width in the radial direction), may be 2 mm or more and 20 mm or less, 2 mm or more and 16 mm or less, 2 mm or more and 12 mm or less, or 2 mm or more and 8 mm or less. In addition, the number of turns of second planar coil 12 is 2 in this embodiment, but may be 3 or more.

[0079] In addition, the inner space of second planar coil 12 is large like first planar coil 11. For details, referring to Figs. 2 and 3, a radial distance D1 from the center of second planar coil 12 to an inner circumferential surface of first turn portion 121 of second planar coil 12 located radially inward is larger than a radial distance D2 from the inner circumferential surface of first turn portion 121 to an outer circumferential surface of second turn portion 122 of second planar coil 12 located radially outward. Distance D1 is preferably at least twice distance D2. However, the shape of second planar coil 12 is not particularly limited.

[0080] Moreover, first planar coil 11 and second planar coil 12 overlap with a gap therebetween. This gap may be 0.5 mm or more and 1.5 mm or less. The size of the gap is not particularly limited, but if the gap is too small, eddy current loss occurring in first planar coil 11 and second planar coil 12 when current is supplied tends to be large. Furthermore, if the gap is too large, the thinning of coil component 10 is hindered.

[0081] In the present embodiment, the thickness of second planar coil 12 is set to 0.01 mm or more and 0.025 mm or less, thereby ensuring the performance of coil device 10 when used in a predetermined frequency band while suppressing an increase in size and weight. The inventors of the present invention have confirmed through experiments and simulations that this effect occurs under conditions that assume at least the radial widths (2 mm to 20 mm) of turn portions 11n, 12n and the number of turns (2) of first planar coil 11 and second planar coil 12 exemplified above. However, the present disclosure is not limited to the conditions exemplified in the embodiment. That is, for example, the effect of ensuring the performance of coil device 10 when used in a predetermined frequency band (500 KHz to 15 MHz) while suppressing an increase in size and weight by setting the thickness of second planar coil 12 to 0.01 mm or more and 0.025 mm or less can occur regardless of the dimensions, the number of turns, etc.

[0082] (Holding body (magnetic member)) As described above, holder 20 holds first planar coil 11 so as to maintain first planar coil 11 and first magnetic shield member 30 in a state separated from each other. Holder 20 also holds first planar coil 11 and second planar coil 12 so as to maintain first planar coil 11 and second planar coil 12 in a state separated from each other. In detail, holder 20 covers surface 111A of first planar coil 11 facing second planar coil 12 and surface 111B opposite surface 111A, and fills the gap between first planar coil 11 and second planar coil 12. This maintains first planar coil 11 and first magnetic shield member 30 in a state separated from each other, and also maintains first planar coil 11 and second planar coil 12 in a state separated from each other. Moreover, holder 20 fills the gap between first planar coil 11 and second planar coil 12, thereby covering surface 121B of second planar coil 12 that faces first planar coil 11.

[0083] On the other hand, holding body 20 does not cover surface 121A of second planar coil 12 opposite surface 121B that faces first planar coil 11. Holding body 20 also includes wall portion 25 that protrudes from second planar coil 12 in the axial direction of second planar coil 12. Wall portion 25 has a spiral shape when viewed in the axial direction of second planar coil 12, and extends along second planar coil 12.

[0084] 2 and 3, holder 20 is annular. This forms a space inside holder 20 and first planar coil 11 and second planar coil 12 held by holder 20, and components related to coil component 10 and other peripheral components can be placed in this space. Holder 20 is formed so that the radial distance from its center to its inner circumferential surface is greater than the radial distance from the inner circumferential surface to the outer circumferential surface. The radial distance from the center of holder 20 to its inner circumferential surface is preferably at least twice the distance from the inner circumferential surface to the outer circumferential surface.

[0085] 3, holder 20 specifically includes first layer 21, second layer 22, third layer 23, fourth layer 24, and wall 25, which are seamlessly and integrally formed. First layer 21, second layer 22, third layer 23, and fourth layer 24 are formed to a size sufficient to encompass first planar coil 11 and second planar coil 12 in their entirety when viewed in the axial direction of first planar coil 11 and second planar coil 12.

[0086] First layer 21 is a portion that covers surface 111B of first planar coil 11 opposite surface 111A facing second planar coil 12, and is in contact with first magnetic shield member 30. Second layer 22 is a portion that overlaps first layer 21 and covers the side surface of first planar coil 11. In other words, second layer 22 is a portion that covers the entire side surface of first planar coil 11 from the inside and outside in the radial direction. Third layer 23 is a portion that is interposed between first planar coil 11 and second planar coil 12. That is, third layer 23 is a portion that fills the gap between first planar coil 11 and second planar coil 12. And fourth layer 24 is a portion that covers the side surface of second planar coil 12. In other words, fourth layer 24 is a portion that covers the entire side surface of second planar coil 12 from the inside and outside in the radial direction. The surface of fourth layer 24 opposite to the surface connected to third layer 23 is flush with surface 121A of second planar coil 12. Wall 25 protrudes from the surface of fourth layer 24 that is flush with surface 121A of second planar coil 12.

[0087] The holder 20 as a whole has magnetic properties, that is, the first layer 21, the second layer 22, the third layer 23, the fourth layer 24, and the wall 25 each have magnetic properties. The holder 20 suppresses eddy current loss and leakage flux by magnetism, and increases the coupling coefficient, thereby improving coil performance. The relative permeability of the holder 20 is preferably 2.0 or more, and may be 2.0 or more and 10.0 or less. The relative permeability of the holder 20 is more preferably 5.0 or more, and may be 5.0 or more and 10.0 or less. The relative permeability of the holder 20 is not particularly limited, but if it is too large, the flexibility and strength of the holder 20 may be undesirably impaired. Therefore, the relative permeability of the holder 20 may be 200 or less.

[0088] Furthermore, the holder 20 is provided with the wall portion 25, which can effectively improve the coil performance. The height of the wall portion 25 is not particularly limited, and may be, for example, 0.1 mm or more, 0.5 mm or more, or 1.0 mm or more. The higher the wall portion 25 is, the higher the effect of suppressing eddy current loss and the higher the coupling coefficient tend to be. On the other hand, the higher the wall portion 25 is, the more likely it is to be damaged starting from its base. Therefore, the height of the wall portion 25 may be, for example, 10 mm or less. The wall portion 25 does not have to be provided.

[0089] The holder 20 in the present embodiment includes, as an example, a resin and a plurality or an infinite number of magnetic particles made of a magnetic material. The magnetic particles are held by the resin as a holding material. The resin has insulating properties. The insulating properties are defined as a property in which the volume resistivity is 10 10 This means that the resistance is Ω·m or more.

[0090] The magnetic particles may be made of any one or more of ferrite, particularly soft magnetic ferrite, nanocrystalline magnetic material, silicon steel, soft magnetic iron, and amorphous metal. The resin as the holding material may be glass fiber reinforced polyamide. That is, the resin may be made of a material containing polyamide as a thermoplastic resin (thermoplastic material) and glass fiber. However, the material of the holding body 20 is not particularly limited.

[0091] (First magnetic shield member) The first magnetic shield member 30 is provided to suppress magnetic transmission and / or leakage magnetic field. The first magnetic shield member 30 is a sheet-like member separate from the first planar coil 11, the second planar coil 12, and the holding body 20. The first magnetic shield member 30 being separate from the first planar coil 11, the second planar coil 12, and the holding body 20 means that the first magnetic shield member 30 is not integrated with the first planar coil 11, the second planar coil 12, and the holding body 20. However, the first magnetic shield member 30 and the holding body 20 may be joined via an adhesive layer or the like. The first magnetic shield member 30 is formed to a size that includes the first planar coil 11 and the second planar coil 12 in a planar view. The first magnetic shield member 30 overlaps the first planar coil 11, the second planar coil 12, and the holding body 20, and is in direct contact with the holding body 20.

[0092] The first magnetic shield member 30 in the present embodiment has magnetism and includes or is made of a magnetic material. In the coil component 10, a magnetic field is generated when a current is supplied to the first planar coil 11 and the second planar coil 12. The magnetic field generated in the coil component 10 spreads in all directions with respect to the central axes C1 and C2 of the first planar coil 11 and the second planar coil 12. At this time, the first magnetic shield member 30 has magnetism, so that the spreading magnetic flux lines can be oriented toward the central axes C1 and C2. In addition, the coil component 10 can be installed in a vehicle or other mobile object such as a drone. In this case, if the magnetic field generated by the coil component 10 flows toward other peripheral components, the peripheral components may be adversely affected. In such a case, the first magnetic shield member 30 can suppress the leakage magnetic field that does not contribute to the generation of the current.

[0093] The first magnetic shield member 30 preferably includes a soft magnetic material or a nanocrystalline magnetic material. More specifically, the first magnetic shield member 30 includes ferrite, preferably soft ferrite. In the present embodiment, the first magnetic shield member 30 includes plate-shaped ferrite. More specifically, the first magnetic shield member 30 is configured by arranging a plurality of plate-shaped ferrites in a sheet shape.

[0094] The relative permeability of the first magnetic shield member 30 may be equal to or greater than 500, or equal to or greater than 1000. The relative permeability of the first magnetic shield member 30 may be equal to or greater than 500 and equal to or less than 3000, or equal to or greater than 1000 and equal to or less than 3000. Note that the relative permeability in this specification is a value measured at a frequency of 85 KHz and an environmental temperature of 23 degrees.

[0095] <Second magnetic shield member> The second magnetic shield member 40 is provided so as to cover the first magnetic shield member 30. In this embodiment, the second magnetic shield member 40 contacts the first magnetic shield member 30. Alternatively, the second magnetic shield member 40 may contact the first magnetic shield member 30 via a spacer. The second magnetic shield member 40 is made of a metal material and has electrical conductivity. Specifically, the second magnetic shield member 40 in this embodiment is made of aluminum. In this case, leakage of magnetism from the first planar coil 11 and the second planar coil 12 through the second magnetic shield member 40 is suppressed. The second magnetic shield member 40 may be made of an aluminum alloy, copper, stainless steel, or the like.

[0096] (Connection terminal) 2, first connection terminal 51 is connected to a radially outer end of turn portion 112 of first planar coil 11. Second connection terminal 52 is connected to a radially outer end of turn portion 122 of second planar coil 12. First connection terminal 51 and second connection terminal 52 can be used, for example, when connecting to high-frequency current supply unit 1A or conversion unit 2A.

[0097] <Manufacturing method of coil parts> Next, an example of a method for manufacturing the coil device 10 according to the first embodiment will be described with reference to FIGS. 5A to 5E.

[0098] First, as shown in FIG. 5A, first planar coil 11 and holder-forming material 110 are prepared and placed between die 101 and punch 102 in a mold. Holder-forming material 110 contains resin and a plurality or an infinite number of magnetic particles made of a magnetic material. The magnetic particles are dispersed in the resin. The resin is a thermoplastic resin, and in this example, contains polyamide and glass fiber. In this example, first planar coil 11 and holder-forming material 110 placed on both sides thereof are sandwiched between die 101 and punch 102. Die 101 and punch 102 have heaters. Punch 102 is provided with spiral-shaped protrusion 102A. Protrusion 102A is a portion for forming wall 25 of holder 20.

[0099] After first planar coil 11 is placed between die 101 and punch 102 as described above, die 101 and punch 102 are pressed against first planar coil 11 and holder-forming material 110 arranged on both sides thereof, and heated, as shown in FIG. 5B. This heat pressing melts and integrates holder-forming material 110 on both sides of first planar coil 11. Holder-forming material 110 then cools and hardens to form holder 20, forming intermediate body 10M in which first planar coil 11 is embedded in holder 20. In the process of forming intermediate body 10M, protrusion 102A of punch 102 is pressed into holder-forming material 110 to form a spiral-shaped recess in holder-forming material 110, and wall portion 25 of holder 20 is formed by a portion that protrudes relative to this recess.

[0100] Thereafter, as shown in FIG. 5C, the intermediate 10M is removed from the metal mold (die 101 and punch 102). Then, as shown in FIG. 5D, a catalyst Mc is provided on a portion (surface of the third layer 23) on one surface of the support 20 of the intermediate 10M where there is no wall 25. The catalyst Mc used here may be, for example, a complex of palladium and tin (Pd-Sn complex). Then, a part of the catalyst Mc is adsorbed on the portion on one surface of the intermediate 10M where there is no wall 25, thereby forming a catalyst layer 12X. Specifically, the tin in the Pd-Sn complex is dissolved to form a catalyst layer 12X containing palladium.

[0101] Then, intermediate body 10M is immersed in a copper solution to grow plated copper on catalyst layer 12X, thereby forming plated layer 12Y as shown in Fig. 5E, thereby forming second planar coil 12. When second planar coil 12 is formed by electroless plating in this manner, etching is not required and the use of complicated production equipment can be suppressed, thereby improving production efficiency.

[0102] <Performance evaluation of coil components> Next, the results of performance evaluation of coil device 10 according to the present embodiment will be described. Fig. 6 shows a graph for explaining the relationship between the thickness of planar coils (11, 12) in coil device 10 and the Q value. In the performance evaluation described below, a plurality of values ​​were set for the thickness of first planar coil 11 and the thickness of second planar coil 12, and the frequency of the supply current was changed to calculate the Q value. Specifically, the Q value was calculated from a simulation. The simulation was performed using Femtet (registered trademark) manufactured by Murata Software Co., Ltd.

[0103] In the simulation described below, a plurality of values ​​were set for the thickness of first planar coil 11 and the thickness of second planar coil 12 in coil device 10 according to the above-described embodiment, and materials were determined for first planar coil 11 and second planar coil 12. Then, the Q value corresponding to each condition was calculated for a plurality of frequencies.

[0104] The individual conditions regarding the thickness and material of first planar coil 11 and second planar coil 12 are as follows. Condition 1: first planar coil 11 is made of aluminum and has a thickness of 0.5 mm. Second planar coil 12 is made of copper and has a thickness of 0.025 mm (Al0.5 / Cu0.025). Condition 2: first planar coil 11 is made of aluminum and has a thickness of 0.5 mm. Second planar coil 12 is made of copper and has a thickness of 0.0125 mm (Al0.5 / Cu0.0125). The above conditions 1 and 2 are the conditions for the coil device 10 according to the embodiment. On the other hand, the comparison conditions for comparison with conditions 1 and 2 are as follows: Comparison condition 1: First planar coil 11 is made of aluminum and has a thickness of 0.5 mm. Second planar coil 12 is made of copper and has a thickness of 0.1 mm (Al0.5 / Cu0.1). Comparison condition 2: first planar coil 11 is made of aluminum and has a thickness of 0.5 mm. Second planar coil 12 is made of copper and has a thickness of 0.05 mm (Al0.5 / Cu0.05). Comparison condition 3: first planar coil 11 is made of aluminum and has a thickness of 0.5 mm. Second planar coil 12 is made of copper and has a thickness of 0.00625 mm (Al0.5 / Cu0.00625).

[0105] The common conditions in the simulations are as follows: The high frequency current supplied is 40A and the frequency is 85KHz. The electrical conductivity of the first planar coil 11 made of aluminum is 3.77×10 7 The electrical conductivity of the second planar coil 12 made of copper is 5.98×10 7 [S / m]. The first magnetic shield member 30 has a relative magnetic permeability of 3000, and the holder 20 has a relative magnetic permeability of 5.0. The second magnetic shield member is made of aluminum. The rear diameter of first planar coil 11 and second planar coil 12 shown in FIG. 2 is 400 mm.

[0106] 6, the line indicated by symbol S1 shows the results for condition 1 (Al0.5 / Cu0.025), the line indicated by symbol S2 shows the results for condition 2 (Al0.5 / Cu0.0125), the line indicated by symbol C1 shows the results for comparative condition 1 (Al0.5 / Cu0.1), the line indicated by symbol C2 shows the results for comparative condition 2 (Al0.5 / Cu0.05), and the line indicated by symbol C3 shows the results for comparative condition 3 (Al0.5 / Cu0.00625).

[0107] 6, in conditions 1 and 2 where the thickness of the second planar coil is 0.01 mm to 0.025 mm, when the frequency of the supply current is 5 MHz or more, 6.78 MHz or more, and particularly 10 MHz or more, the Q value becomes smaller than, equal to, or larger than the Q value in comparative conditions 1 and 2 where the coil thickness is larger than that in conditions 1 and 2. That is, this means that conditions 1 and 2 can ensure high performance while reducing weight and size with a small amount of copper used. Such results support the effect of the present disclosure that by setting the thickness of second planar coil 12 to 0.01 mm or more and 0.025 mm or less, it is possible to efficiently function a multi-layered planar coil while suppressing the increase in size and weight of coil component 10.

[0108] Although the results in Fig. 6 are evaluation results when an AC current is supplied to generate a magnetic field, the Q value is also increased when an AC current is generated by receiving an AC magnetic field. Therefore, the evaluation results in Fig. 6 support the fact that the coil device 10 functions effectively even when an AC magnetic field of 5 MHz or more, 6.78 MHz or more, and particularly 10 MHz or more is supplied.

[0109] <Applications of coil components> The coil component 10 according to this embodiment can be used as a power transmitting coil in the power transmitting device 1 of the wireless power transmission system S described above, and can be used as a power receiving coil in the power receiving device 2.

[0110] When coil component 10 is used as a power transmission coil, first connection terminal 51 and second connection terminal 52 are connected to high-frequency current supply unit 1A or an AC power source as shown in Fig. 1. When high-frequency current is supplied to coil component 10, the current can be passed from first connection terminal 51 to first planar coil 11 and second planar coil 12, and then passed from second connection terminal 52 to high-frequency current supply unit 1A or an AC power source. Also, the current can be passed from second connection terminal 52 to second planar coil 12 and first planar coil 11, and then passed from first connection terminal 51 to high-frequency current supply unit 1A or an AC power source. This makes it possible to generate a magnetic field including magnetic field lines along the central axis of the planar coil.

[0111] On the other hand, when coil device 10 is used as a receiving coil, a high-frequency current can be generated in first planar coil 11 and second planar coil 12 by receiving a magnetic field including magnetic field lines passing through the inside of first planar coil 11 and second planar coil 12. Then, this high-frequency current can be supplied to an external device from first connection terminal 51 or second connection terminal 52.

[0112] The coil component 10 can also be used in a transformer, an antenna, etc. For example, when the coil component 10 functions as a primary coil in a transformer, the first connection terminal 51 and the second connection terminal 52 are connected to an AC power source. When a high-frequency current is supplied, a magnetic flux can be supplied from the center of the planar coil to the iron core.

[0113] Coil device 10 according to the present embodiment described above includes first planar coil 11, second planar coil 12 overlapping first planar coil 11, and holder 20 which is a magnetic member having magnetism and includes first layer 21 covering the surface of first planar coil 11 opposite to the surface facing second planar coil 12. First planar coil 11 and second planar coil 12 are connected in series, and second planar coil 12 has a thickness of 0.01 mm or more and 0.025 mm or less.

[0114] According to the coil component 10 of the present embodiment, the multi-layered planar coil can function efficiently while suppressing the increase in size and weight. Generally speaking, it is assumed that the thicker the coil, the higher the inductance obtained in the coil, and the more the coil performance such as the Q value tends to improve. However, the present inventors have found through intensive research that such a tendency does not necessarily occur in a configuration in which a planar coil is stacked in series on a magnetic member. The present inventors have found that, in a configuration in which the first planar coil 11 and the second planar coil 12 are stacked in this order on a magnetic member (the holder 20 and the first magnetic shield member 30), when an AC current or an AC magnetic field in a predetermined frequency band (5 MHz or more, 6.78 MHz or more, particularly 10 MHz or more) is supplied, a high Q value can be ensured in spite of the extremely thin thickness when the thickness of the second planar coil 12 is between 0.01 mm and 0.025 mm, regardless of the thickness of the first planar coil 11. This finding has revealed that the performance of coil device 10 can be improved by using second planar coil 12 having a thickness of, for example, 0.025 mm, rather than using second planar coil 12 having a thickness of 0.05 mm.

[0115] That is, in the coil component 10 based on such knowledge, by setting the thickness of the second planar coil 12 to 0.01 mm or more and 0.025 mm or less, the second planar coil 12 can be made thin and lightweight. And the performance of the coil component 10 can be improved as much as possible when used in a predetermined frequency band. This can improve the performance of the coil component 10 while suppressing the increase in the overall size and weight of the coil component 10. For example, it is a phenomenon that is difficult to predict from technical common sense that the performance of the coil component 10 can be improved by using the second planar coil 12 having a thickness of 0.025 mm compared to the case where the second planar coil 12 having a thickness of 0.5 mm or 0.05 mm is used. It is believed that the above coil component invented based on such a phenomenon has a remarkable effect that greatly contributes to the improvement of the performance of the coil component. Furthermore, a material containing aluminum is used as the material of the first planar coil 11. This can more effectively suppress the weight increase and keep costs down while ensuring a reasonably high coil performance.

[0116] The thickness of first planar coil 11 is preferably 0.4 mm or more and 0.6 mm or less. With this configuration, good coil performance can be obtained while suppressing increases in thickness and weight.

[0117] In the present embodiment, holding body 20 includes resin and magnetic particles held by the resin. In this case, the bonding strength between the resin and first planar coil 11 and second planar coil 12 can be improved, so that first planar coil 11 and second planar coil 12 can be integrated in a stable state.

[0118] The relative magnetic permeability of the holder 20 may be 5.0 or more. In this case, the performance of the coil component can be improved by the magnetic permeability of the holder 20. The relative magnetic permeability of the holder 20 may be 10.0 or less. In this case, the strength of the holder 20 can be appropriately ensured, and the bond between the holder 20 and each of the planar coils 11 and 12 can be strengthened.

[0119] Moreover, holder 20 in the present embodiment includes wall portion 25 protruding from second planar coil 12. This configuration can effectively improve the transmission efficiency of magnetic flux sent from coil component 10 or received from other coil components.

[0120] Moreover, in this embodiment, the holder 20 is annular. This allows the weight of the holder 20 to be reduced. Also, a space is formed inside the holder 20, and components related to the coil component 10 and other peripheral components can be disposed in this space. In other words, the space inside the holder 20 can be effectively utilized.

[0121] In particular, in the present embodiment, the radial distance from the center of first planar coil 11 to the inner circumferential surface of first turn portion 111 of first planar coil 11 located radially inward is greater than the radial distance from the inner circumferential surface of first turn portion 111 to the outer circumferential surface of second turn portion 112 of first planar coil 11 located radially outward. Also, the radial distance from the center of second planar coil 12 to the inner circumferential surface of first turn portion 121 of second planar coil 12 located radially inward is greater than the radial distance from the inner circumferential surface of first turn portion 121 to the outer circumferential surface of second turn portion 122 of second planar coil 12 located radially outward. And, in holding body 20, the radial distance from its center to the inner circumferential surface is greater than the radial distance from the inner circumferential surface to the outer circumferential surface. This allows the space inside first planar coil 11, second planar coil 12, and holding body 20 to be effectively utilized.

[0122] Moreover, first planar coil 11 and second planar coil 12 each include, as the multiple turn portions, only a first turn portion and a second turn portion located radially outward from the first turn portion. In this case, even if the distance over which power is transmitted becomes relatively long, efficient power transmission is possible, and this is also advantageous in terms of weight reduction. The present inventors have confirmed this through experiments, etc.

[0123] <Second embodiment> Next, a coil device 10a according to a second embodiment will be described with reference to Fig. 7 to Fig. 9. Among the components of the embodiment described below, the same components as those of the first embodiment will be denoted by the same reference numerals and will not be described.

[0124] 7 and 8, the coil component 10a according to the second embodiment does not include the second magnetic shield member 40. In such an embodiment, the magnetic shielding effect of the second magnetic shield member 40 is lost, but the coil component 10a can function more efficiently. Such an embodiment is suitable for application to a power transmission device.

[0125] 9 shows a graph for explaining the relationship between the thickness of the planar coils (11, 12) in coil device 10a and the Q value. In the performance evaluation described below, a plurality of values ​​were set for the thickness of first planar coil 11 and the thickness of second planar coil 12, and the frequency of the supply current was changed to calculate the Q value. Specifically, the Q value was calculated from a simulation. The simulation was performed using Femtet (registered trademark) manufactured by Murata Software Co., Ltd.

[0126] In the simulation described below, a plurality of values ​​were set for the thickness of first planar coil 11 and the thickness of second planar coil 12 in coil component 10a according to the second embodiment, and the materials of first planar coil 11 and second planar coil 12 were determined. Then, the Q value corresponding to each condition was calculated for a plurality of frequencies. The specific conditions of the simulation are the same as those described in the first embodiment. In FIG. 9, the line indicated by symbol S11 shows the result of condition 1 (Al0.5 / Cu0.025), and the line indicated by symbol S12 shows the result of condition 2 (Al0.5 / Cu0.0125). The line indicated by symbol C11 shows the result of comparative condition 1 (Al0.5 / Cu0.1), the line indicated by symbol C12 shows the result of comparative condition 2 (Al0.5 / Cu0.05), and the line indicated by symbol C13 shows the result of comparative condition 3 (Al0.5 / Cu0.00625).

[0127] 9, in conditions 11 and 12 where the thickness of the second planar coil is 0.01 mm to 0.025 mm, when the frequency of the supply current is 5 MHz or more, 6.78 MHz or more, and particularly 10 MHz or more, the Q value becomes smaller than, equal to, or larger than the Q value in the comparative conditions 1 and 2 where the coil thickness is larger than that in conditions 1 and 2. That is, this means that conditions 1 and 2 can ensure high performance while reducing weight and size with a small amount of copper used. Such results support the effect that by setting the thickness of second planar coil 12 to 0.01 mm or more and 0.025 mm or less, the multi-layered planar coil can be efficiently operated while preventing the coil component 10 from becoming large and heavy.

[0128] 9 is an evaluation result when an AC current is supplied to generate a magnetic field, but the Q value is also increased when an AC current is generated by receiving an AC magnetic field. Therefore, the evaluation result in FIG. 9 supports the fact that the coil device 10b functions effectively even when an AC magnetic field of 5 MHz or more, 6.78 MHz or more, and especially 10 MHz or more is supplied.

[0129] <Third embodiment> Next, a coil device 10b according to a third embodiment will be described with reference to Fig. 10 to Fig. 12. Among the components of the embodiment described below, the same components as those of the first and second embodiments will be denoted by the same reference numerals and will not be described.

[0130] 10 and 11, the coil component 10b according to the third embodiment does not include the first magnetic shield member 30 and the second magnetic shield member 40. In such an embodiment, the magnetic shielding effect provided by the first and second magnetic shield members 30 and 40 is lost, but the coil component 10b can function more efficiently. Such an embodiment is suitable for application to a power transmission device.

[0131] 12 shows a graph illustrating the relationship between the thickness of the planar coils (11, 12) in coil device 10a and the Q value. In the performance evaluation described below, a plurality of values ​​were set for the thickness of first planar coil 11 and the thickness of second planar coil 12, and the frequency of the supply current was changed to calculate the Q value. Specifically, the Q value was calculated from a simulation. The simulation was performed using Femtet (registered trademark) manufactured by Murata Software Co., Ltd.

[0132] In the simulation described below, a plurality of values ​​were set for the thickness of first planar coil 11 and the thickness of second planar coil 12 in coil component 10b according to the third embodiment, and the materials of first planar coil 11 and second planar coil 12 were determined. Then, the Q value corresponding to each condition was calculated for a plurality of frequencies. The specific conditions of the simulation are the same as those described in the first embodiment. In FIG. 9, the line indicated by symbol S21 shows the result of condition 1 (Al0.5 / Cu0.025), and the line indicated by symbol S22 shows the result of condition 2 (Al0.5 / Cu0.0125). The line indicated by symbol C21 shows the result of comparative condition 1 (Al0.5 / Cu0.1), the line indicated by symbol C22 shows the result of comparative condition 2 (Al0.5 / Cu0.05), and the line indicated by symbol C23 shows the result of comparative condition 3 (Al0.5 / Cu0.00625).

[0133] 12, in conditions 1 and 2 where the thickness of the second planar coil is 0.01 mm to 0.025 mm, when the frequency of the supply current is 6.78 MHz or more, particularly 10 MHz or more, the Q value becomes smaller than, equal to, or larger than the Q value in comparative conditions 1 and 2 where the coil thickness is larger than that in conditions 1 and 2. That is, this means that conditions 1 and 2 can ensure high performance while reducing weight and size with a small amount of copper used. Such results support the effect that by setting the thickness of second planar coil 12 to 0.01 mm or more and 0.025 mm or less, the multi-layered planar coil can be efficiently operated while preventing the coil component 10 from becoming large and heavy.

[0134] 12 is an evaluation result when an AC current is supplied to generate a magnetic field, but the Q value is also increased when an AC current is generated by receiving an AC magnetic field. Therefore, the evaluation result in FIG. 12 supports the fact that the coil component 10b functions effectively even when an AC magnetic field of 6.78 MHz or more, particularly 10 MHz or more, is supplied.

[0135] <Application to drones> 13 and 14 are diagrams illustrating an example in which the coil components 10 and 10b according to the first and third embodiments are applied to a power transmission system for a drone.

[0136] 13, a drone 200 is provided with a power receiving device 2 including the coil device 10 according to the first embodiment. A power transmitting device 1 provided at a power supply spot is provided with a coil device 10b according to the third embodiment.

[0137] In the example of FIG. 14, the drone 200 is provided with the coil component 10 according to the first embodiment and the coil component 10b according to the third embodiment. In the drone 200, the coil component 10b is disposed below the coil component 10. The coil components 10 and 10b are stacked such that the central axes of the planar coils (11, 12) included in each of them are coaxial or parallel. The coil components 10 and 10b are not electrically connected. The high-frequency current supply unit 1A is connected to the coil component 10. Meanwhile, in the coil component 10b, the first connection terminal 51 and the second connection terminal 52 are connected via a capacitor.

[0138] The power transmission device 1 provided at the power supply spot shown in FIG. 14 also includes the coil component 10 according to the first embodiment and the coil component 10b according to the third embodiment. In the power transmission device 1, the coil component 10b is disposed above the coil component 10. The coil components 10 and 10b are stacked such that the central axes of the planar coils (11, 12) included in each of them are coaxial or parallel. The coil components 10 and 10b are not electrically connected. The high-frequency current supply unit 1A is connected to the coil component 10. Meanwhile, in the coil component 10b, the first connection terminal 51 and the second connection terminal 52 are connected via a capacitor.

[0139] Although the embodiment of the present disclosure has been described above, various modifications may be made to the above-described embodiment, and such modifications are also within the technical scope of the present disclosure. [Explanation of symbols]

[0140] S…Power transmission system 1...Power transmission device 1A…High frequency current supply 2...Power receiving device 2A…Conversion section 10...Coil parts 10M…Intermediate 11…First planar coil 11n, 111~112...Turn section 111…First turn 112…Second turn 11E…Conductor 12…Second planar coil 12n, 121~122...Turn section 121…First turn 122…Second turn 12E…Conductor 12X…Catalyst layer 12Y…Plating layer 20...Holding body 21…First layer 22…Second layer 23…Third layer 24…Fourth layer 25…Wall part 30...First magnetic shield member 40...Second magnetic shield member 51…First connection terminal 52…Second connection terminal 110...Holding body forming material 101…Die 102...Punch 102A…Convex part 200…Drone C1…First central axis line C2…Second central axis line Mc…Catalyst metal

Claims

1. A first planar coil; a second planar coil overlapping the first planar coil; a first layer covering a surface of the first planar coil opposite to a surface facing the second planar coil, the first layer including a magnetic member having magnetism; the first planar coil and the second planar coil are connected in series; The second planar coil has a thickness of 0.01 mm or more and 0.025 mm or less.

2. The coil component according to claim 1 , wherein the first planar coil has a thickness of 0.4 mm or more and 0.6 mm or less.

3. the first planar coil comprises aluminum; The coil component of claim 1 , wherein the second planar coil comprises copper.

4. the magnetic member integrally holds the first planar coil and the second planar coil in a state in which the first planar coil and the second planar coil overlap with a gap therebetween, The coil component according to claim 1 , wherein the magnetic member further includes a second layer portion covering a side surface of the first planar coil, and a third layer portion filling the gap.

5. The coil component according to claim 1 , wherein the magnetic member includes a wall portion protruding from the second planar coil.

6. The coil component according to claim 1 , wherein the magnetic member includes a resin and magnetic particles held by the resin.

7. The coil component according to claim 1 , wherein the magnetic member has a relative permeability of 5.0 or more.

8. The coil component according to claim 1 , wherein the magnetic member is annular.

9. The coil component according to claim 1 , further comprising a magnetic shield member arranged to face a surface of the first layer portion of the magnetic member opposite to a surface facing the first planar coil.

10. The coil component according to claim 9 , wherein the magnetic shield member includes a plate-shaped ferrite.

11. The coil component according to claim 9 , wherein the magnetic shielding member has a relative permeability of 500 or more.

12. each of the first planar coil and the second planar coil includes a plurality of turns arranged in a radial direction; a distance in the radial direction from a center of the first planar coil to an inner circumferential surface of the turn portion of the first planar coil located at the innermost position in the radial direction is greater than a distance in the radial direction from an inner circumferential surface of the turn portion of the first planar coil located at the innermost position in the radial direction to an outer circumferential surface of the turn portion of the first planar coil located at the outermost position in the radial direction, 2. The coil component according to claim 1, wherein a radial distance from a center of the second planar coil to an inner circumferential surface of the turn portion of the second planar coil that is located most inward in the radial direction is greater than a radial distance from an inner circumferential surface of the turn portion of the second planar coil that is located most inward in the radial direction to an outer circumferential surface of the turn portion of the first planar coil that is located most outward in the radial direction.

13. the first planar coil and the second planar coil each include the same number of turn portions; The coil component according to claim 12 , wherein the turn portion of the first planar coil and the turn portion of the second planar coil that are at the same position when counted from their respective centers at least partially overlap each other.

14. 13. The coil component according to claim 12, wherein the first planar coil and the second planar coil each include, as the plurality of turn portions, only a first turn portion and a second turn portion located radially outward from the first turn portion.

15. The coil component according to claim 1 , wherein the second planar coil includes a catalyst layer attached to the magnetic member, and a plating layer laminated on the catalyst layer.

16. A first planar coil; a second planar coil overlapping the first planar coil; a member including a first layer portion covering a surface of the first planar coil opposite to a surface facing the second planar coil, the first planar coil and the second planar coil are connected in series; The second planar coil has a thickness of 0.01 mm or more and 0.025 mm or less.

17. 17. The coil component according to claim 1, wherein the first planar coil and the second planar coil are supplied with an AC current of 10 MHz or more, or an AC magnetic field of 500 KHz to 15 MHz.

18. A coil component according to any one of claims 1 to 16, a high-frequency current supply unit that supplies an alternating current of 10 MHz or more to the coil component.

19. A coil component according to any one of claims 1 to 16, A conversion unit that converts an AC current of 10 MHz or more generated by electromagnetic induction in the coil component into a DC current.

20. The power transmission device and the power receiving device are provided. A power transfer system, wherein at least one of the power transmitting device and the power receiving device comprises the coil component according to claim 1 .

21. A step of supplying an AC current of 10 MHz or more to a coil component in a power transmission device including the coil component according to any one of claims 1 to 16; generating a current in a power receiving device based on a magnetic field generated in the power transmitting device,

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