Coil component, power transmission device, power reception device, mobile body, and power transmission system

Abstract

To improve a production efficiency of a coil component.SOLUTION: In a power transmission system, a coil component 5 comprises a coil 10 containing first and second flat surface coil elements 11 and 12. Each of the first and second flat surface coil elements has a spiral shape having a plurality of turn parts 111 to 116, and 121 to 123. Each of the first and second flat surface coil elements is arranged opposing to each other in a shaft direction extending on center shaft wires C1 and C2 in this spiral shape. The first and second flat surface coil elements is serially connected to each other. The number of turns of the second flat surface coil element is smaller than the number of turns of the first flat surface coil element. Also, in view of the shaft direction, at least one of the plurality of turn parts of the second flat surface coil element is overlapped to two or more of the plurality of turn parts of the first flat surface coil element. Also, each gap between the plurality of turn parts of the second flat surface coil element in the shaft direction is overlapped with any one of the gaps between the plurality of turn parts of the first flat surface coil element.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a coil component, a power transmitting device, a power receiving device, a moving body, and a power transfer system. [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] When transmitting power contactlessly, a high-frequency current flows through a resonant circuit including a coil. A coil component used in such a resonant circuit is disclosed in Patent Document 1. The coil component disclosed in Patent Document 1 uses a coil formed by stacking two spiral, plate-like planar coil elements. This makes it possible to reduce the dimensions of the coil in a planar view.

[0004] When forming a coil as a laminate of two planar coil elements, as disclosed in Patent Document 1, two planar coil elements of the same or corresponding patterns (i.e., having the same number of turns and pitch of the turns) are produced, stacked one on top of the other, and electrically connected. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-27112 Summary of the Invention [Problem to be solved by the invention]

[0006] On the other hand, there is a demand for improving the manufacturing efficiency of coil components. The manufacturing efficiency of coil components can be improved, for example, by improving the handleability of members constituting the coil components. In particular, in the case of coil components having a small thickness of planar coil elements, the difficulty in handling the planar coil elements when assembling the coil components is a problem.

[0007] An embodiment of the present disclosure aims to improve the manufacturing efficiency of coil components. [Means for solving the problem]

[0008] One embodiment of the present disclosure relates to the following [1] to

[19] .

[0009] [1] a coil including a first planar coil element and a second planar coil element, each of which has a spiral shape with a plurality of turns, which are arranged opposite each other in an axial direction extending along a central axis of the spiral shape and connected in series with each other; the number of turns of the second planar coil element is less than the number of turns of the first planar coil element, When viewed in the axial direction, at least one of the plurality of turn portions of the second planar coil element overlaps with two or more of the plurality of turn portions of the first planar coil element; a coil component in which, as viewed in the axial direction, each gap between the plurality of turn portions of the second planar coil element overlaps with any one of the gaps between the plurality of turn portions of the first planar coil element.

[0010] [2] the number of turns of the first planar coil element is twice the number of turns of the second planar coil element; The coil component according to [1], wherein each turn portion of the second planar coil element overlaps with two turn portions of the first planar coil element when viewed in the axial direction.

[0011] [3] The coil component according to [1] or [2], wherein, when viewed in the axial direction, an inner edge of each turn portion of the second planar coil element overlaps with an inner edge of any turn portion of the first planar coil element, and an outer edge of each turn portion of the second planar coil element overlaps with an outer edge of any turn portion of the first planar coil element.

[0012] [4] The coil component according to any one of [1] to [3], wherein a slot is formed in each of the plurality of turn portions of the second planar coil element, the slot extending along the turn portions.

[0013] [5] The coil component according to [4], wherein the long hole extends along the spiral shape of the second planar coil element.

[0014] [6] The coil component according to [4] or [5], wherein, when viewed in the axial direction, the long hole overlaps with any one of the gaps between the plurality of turn portions of the first planar coil element.

[0015] [7] The coil component according to any one of [1] to [6], wherein the second planar coil element has a thickness of 0.15 mm or more and 0.35 mm or less.

[0016] [8] The coil component according to any one of [1] to [7], further comprising a magnetic shield member disposed opposite the second planar coil element.

[0017] [9] a magnetic wall portion extending along the axial direction and extending along gaps between the plurality of turn portions of the first planar coil element as viewed in the axial direction, The coil component according to [8], wherein the magnetic wall portion is arranged facing a second surface of the first planar coil element opposite a first surface facing the second planar coil element.

[0018]

[10] a magnetic wall portion extending along the axial direction and extending along gaps between the plurality of turn portions of the first planar coil element as viewed in the axial direction, The coil component described in [8], wherein the magnetic wall portion extends along the axial direction from one side to the other side of the first planar coil element through gaps between multiple turn portions of the first planar coil element.

[0019]

[11] The coil component according to any one of [1] to [7], further comprising a magnetic shield member disposed opposite the first planar coil element.

[0020]

[12] a magnetic wall portion extending along the axial direction and extending along gaps between the plurality of turn portions of the second planar coil element as viewed in the axial direction, The coil component according to

[11] , wherein the magnetic wall portion is disposed opposite a fourth surface of the second planar coil element opposite a third surface facing the first planar coil element.

[0021]

[13] a magnetic wall portion extending along the axial direction and extending along gaps between the plurality of turn portions of the second planar coil element as viewed in the axial direction, The coil component according to

[11] , wherein the magnetic wall portion extends along the axial direction from one side to the other side of the second planar coil element through gaps between a plurality of turn portions of the second planar coil element.

[0022]

[14] a long hole is formed in each of the plurality of turn portions of the second planar coil element, the long hole extending along the turn portions; The coil component further includes an additional magnetic wall portion, The additional magnetic wall portion extends along the axial direction and extends along the long hole when viewed in the axial direction, The coil component according to any one of

[11] to

[13] , wherein the additional magnetic wall portion is arranged facing a fourth surface of the second planar coil element opposite a third surface facing the first planar coil element.

[0023]

[15] a long hole is formed in each of the plurality of turn portions of the second planar coil element, the long hole extending along the turn portions; The coil component further includes an additional magnetic wall portion, The additional magnetic wall portion extends along the axial direction and extends along the long hole when viewed in the axial direction, The method for manufacturing a coil component according to any one of

[11] to

[13] , wherein the additional magnetic wall portion extends along the axial direction from one side to the other side of the second planar coil element through the long hole formed in multiple turns of the second planar coil element.

[0024]

[16] A power transmitting device comprising the coil component according to any one of [1] to

[15] .

[0025]

[17] A power receiving device comprising the coil component according to any one of [1] to

[15] .

[0026]

[18]

[17] A mobile object comprising the power receiving device described in

[17] .

[0027]

[19] 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 includes the coil component according to any one of [1] to

[15] . Effect of the Invention

[0028] According to an embodiment of the present disclosure, it is possible to improve the manufacturing efficiency of coil components. [Brief description of the drawings]

[0029] [Figure 1] 1 is a diagram illustrating a schematic diagram of a wireless power transmission system to which a coil component according to an embodiment is applied. [Diagram 2] FIG. 1 is a perspective view of a coil component according to an embodiment. [Diagram 3] 3 is a cross-sectional view taken along line III-III of the coil device shown in FIG. 2. [Figure 4] FIG. 4 is an exploded perspective view of a coil of the coil component shown in FIG. [Diagram 5] FIG. 4 is a cross-sectional view corresponding to FIG. 3 and showing a modified example of the coil component. [Figure 6] FIG. 4 is a cross-sectional view corresponding to FIG. 3 and showing another modified example of the coil component. [Figure 7] FIG. 7 is an exploded perspective view of a coil of the coil component shown in FIG. 6. [Figure 8] FIG. 4 is a cross-sectional view corresponding to FIG. 3 and showing still another modified example of the coil component. [Figure 9] FIG. 4 is a cross-sectional view corresponding to FIG. 3 and showing still another modified example of the coil component. [Figure 10] 10 is an exploded perspective view of a coil of the coil component shown in FIG. 9. [Figure 11] FIG. 4 is a cross-sectional view corresponding to FIG. 3 and showing still another modified example of the coil component. [Figure 12] FIG. 3 is a perspective view corresponding to FIG. 2 and showing still another modified example of the coil component. [Figure 13] 13 is a cross-sectional view taken along line XIII-XIII of the coil device shown in FIG. 12. [Figure 14] FIG. 14 is an exploded perspective view of a coil of the coil device shown in FIG. 13. [Figure 15] FIG. 14 is a cross-sectional view corresponding to FIG. 13 and showing still another modified example of the coil component. [Figure 16] FIG. 4 corresponds to FIG. 3 and shows cross sections of coil components according to comparative examples 1 to 3. [Figure 17] FIG. 4 corresponds to FIG. 3 and shows a cross section of a coil component according to Comparative Example 4. [Figure 18] FIG. 4 corresponds to FIG. 3 and shows a cross section of a coil component according to Comparative Example 5. [Figure 19] FIG. 4 corresponds to FIG. 3 and shows a cross section of a coil component according to Comparative Example 6. [Figure 20] 1 is a table showing the performance of coil components of Examples 1 to 4 and Comparative Examples 1 to 6. [Figure 21] 1 is a graph showing the performance of coil parts according to Examples 1 to 4 and Comparative Examples 1 to 6. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] An embodiment and its modified examples will be described below with reference to the drawings. In the drawings attached to this specification, the scale and the aspect ratio are appropriately changed and exaggerated from those of the actual objects for the convenience of illustration and understanding.

[0031] In addition, in this specification, terms such as "sheet," "film," and "plate" 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 and plates.

[0032] Fig. 1 shows a schematic diagram of a wireless power transmission system S to which a coil component 5 according to an 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 a coil component different from the coil component 5 according to the present embodiment can be applied to the power transmission system S.

[0033] <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 5 and a high-frequency current supplying unit 1A. The coil component 5 in the power transmitting device 1 functions as a power transmitting coil component. The high-frequency current supplying unit 1A supplies a high-frequency current to the coil component 5 serving as a power transmitting coil component.

[0034] The power receiving device 2 includes a coil component 5 and a conversion unit 2A. The coil component 5 in the power receiving device 2 functions as a power receiving coil component. The conversion unit 2A shapes a high-frequency current generated in the coil component 5. 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 include, for example, a full-wave rectifier circuit including a plurality of diodes and a smoothing capacitor.

[0035] In this embodiment, each of the power transmitting device 1 and the power receiving device 2 includes a coil component 5. However, the coil component 5 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.

[0036] 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 5 serving as a power transmitting coil component. At this time, a magnetic field is generated in the coil component 5 by electromagnetic induction. Then, due to the influence of this magnetic field, a high-frequency current is generated in the coil component 5 serving as a power receiving coil component in the power receiving device 2. That is, the power receiving device 2 receives a magnetic field from the power transmitting device 1 or is influenced by the magnetic field in the power transmitting device 1, and causes a 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.

[0037] The power transmission system S shown in Fig. 1 employs a magnetic resonance method as a power transmission method. However, the coil component 5 according to the present embodiment may be used in a power transmission system that employs an electromagnetic induction method. The power transmission system S is configured as a system that wirelessly transmits power to an electric vehicle. In this case, the power transmitting device 1 is installed on a road, a parking lot, or the like. The power receiving device 2 is installed in the electric vehicle.

[0038] However, the use of the power transmission system S is not limited to power transmission to electric vehicles. For example, the power transmission system S may be used to transmit power to flying objects such as drones and robots. The power transmission system S may also be used to transmit power to submersibles and exploration robots in the sea. In this way, the power transmission system S can be used to transmit power to various moving objects such as electric vehicles, flying objects, robots, and submersibles. The use of the coil component 5 is not limited to wireless power transmission systems. For example, the coil component 5 may be used in transformers, DC-DC converters, antennas, and the like.

[0039] <Coil parts> The coil component 5 will now be described. Fig. 2 is a perspective view of the coil component 5. Fig. 3 is a cross-sectional view of the coil component 5 taken along line III-III in Fig. 2. Fig. 4 is an exploded perspective view of the coil 10 included in the coil component 5.

[0040] As shown in FIGS. 2 and 3, the coil device 5 includes a coil 10, a magnetic shield member 20, a holder 30, a magnetic wall portion 40, a first connection terminal 51, and a second connection terminal 52.

[0041] As shown in FIG. 3, coil 10 includes a back side surface 10a facing magnetic shield member 20 and a front side surface 10b opposite to back side surface 10a. Coil 10 also includes first planar coil element 11 and second planar coil element 12. In the example shown in FIG. 3, first planar coil element 11 forms front side surface 10b, and second planar coil element 12 forms back side surface 10a. In other words, in coil component 5 shown in FIG. 3, second planar coil element 12 and first planar coil element 11 are arranged on magnetic shield member 20 so as to overlap in this order. First planar coil element 11 and second planar coil element 12 are connected in series and overlap with a gap therebetween. Second planar coil element 12 and magnetic shield member 20 also overlap with a gap therebetween.

[0042] The holder 30 functions to maintain a gap between the first planar coil element 11 and the second planar coil element 12, and to maintain a gap between the second planar coil element 12 and the magnetic shield member 20. The holder 30 also functions to integrate the first planar coil element 11 and the second planar coil element 12.

[0043] (First planar coil element and second planar coil element) The first planar coil element 11 and the second planar coil element 12 have a spiral shape as shown in FIG. 2 and FIG. 4. The first planar coil element 11 and the second planar coil element 12 are made of a conductive material. In the present embodiment, the first planar coil element 11 and the second planar coil element 12 contain copper. Specifically, the first planar coil element 11 and the second planar coil element 12 are made of copper. However, the first planar coil element 11 and the second planar coil element 12 may be made of a copper alloy, aluminum, an aluminum alloy, or the like. The first planar coil element 11 and the second planar coil element 12 may be made of conductive materials different from each other.

[0044] The first planar coil element 11 and the second planar coil element 12 are plate-shaped, as shown in Fig. 3 and Fig. 4. As shown in Fig. 3, the cross-sectional shape of the first planar coil element 11 in a direction perpendicular to the direction in which the first planar coil element 11 winds around in a spiral shape is rectangular. Similarly, the cross-sectional shape of the second planar coil element 12 in a direction perpendicular to the direction in which the second planar coil element 12 winds around in a spiral shape is rectangular.

[0045] First planar coil element 11 has a first surface 11a facing second planar coil element 12 and a second surface 11b opposite to first surface 11a. In the example shown in FIG. 4, second surface 11b forms front surface 10b of coil 10.

[0046] Second planar coil element 12 has a third surface 12a facing first planar coil element 11 and a fourth surface 12b opposite to third surface 12a. In the example shown in FIG. 4, fourth surface 12b forms backside surface 10a of coil 10.

[0047] Reference symbol C1 in FIGS. 2 to 4 indicates the first central axis of the first planar coil element 11 passing through the center of the spiral shape of the first planar coil element 11. Hereinafter, the "axial direction of the first planar coil element 11" means a direction extending on the first central axis C1 or a direction parallel to the first central axis C1. Moreover, the "radial direction of the first planar coil element 11" means a radial direction of a circle drawn on a plane centered on an arbitrary point on the first central axis C1 and perpendicular to the first central axis C1. Moreover, the radial inward direction of the first planar coil element 11 and the turn portion 11n constituting the first planar coil element 11 means a direction approaching the first central axis C1 in the radial direction. Moreover, the radial outward direction of the first planar coil element 11 and the turn portion 11n means a direction moving away from the first central axis C1 in the radial direction.

[0048] 2 to 4 indicates the second central axis of the second planar coil element 12 passing through the center of the spiral shape of the second planar coil element 12. Hereinafter, the "axial direction of the second planar coil element 12" means a direction extending on the second central axis C2 or a direction parallel to the second central axis C2. The "radial direction of the second planar coil element 12" means a radial direction of a circle drawn on a plane centered on an arbitrary point on the second central axis C2 and perpendicular to the second central axis C2. The radial inward direction of the second planar coil element 12 and the turn parts 12n constituting the second planar coil element 12 means a direction approaching the second central axis C2 in the radial direction. The radial outward direction of the second planar coil element 12 and the turn parts 12n means a direction moving away from the second central axis C2 in the radial direction.

[0049] In this embodiment, second planar coil element 12 is arranged to be coaxial with first planar coil element 11. That is, first central axis C1 of first planar coil element 11 and second central axis C2 of second planar coil element 12 coincide with each other. In other words, first central axis C1 and second central axis C2 are positioned on the same straight line.

[0050] The first planar coil element 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 element 11 are arranged in a 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 in a radially outward direction. This forms the spiral shape.

[0051] 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.

[0052] Hereinafter, the turn portion 11n that is 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 the following, when describing matters common to each of the turn portions 11n, they will basically be referred to as the turn portion 11n.

[0053] In this embodiment, the turn portion 11n goes around to form a rectangular shape. However, the turn portion 11n may also have a shape that goes around to form a circle. Note that the spiral shape in this specification and this disclosure means a planar curve shape that is wound in a spiral shape. The planar curve here includes a planar pattern that goes around repeatedly while bending in a broken line shape as shown in the figure. In other words, the spiral shape means a planar curve shape that moves away from the center as it goes around (or approaches the center as it goes around).

[0054] Similarly, the second planar coil element 12 has a conductor 12E having a spiral shape formed by a plurality of turn portions 12n. The plurality of turn portions 12n of the second planar coil element 12 are arranged in a direction perpendicular to the second central axis C2 of the spiral shape. More specifically, the plurality of turn portions 12n are connected so as to gradually move away from the second central axis C2 of the spiral shape in a radially outward direction. This forms the spiral shape.

[0055] The turn portion 12n is basically a shape in which a linear conductor portion does not form a loop but goes around the second central axis C2 360 degrees. In the case of a so-called planar coil, both ends of the turn portion 12n are shifted in the radial direction. In the case of the multiple turn portions 12n, the radially outer end of one turn portion 12n is connected to the radially inner end of another turn portion 12n, and the other turn portions 12n extend away from the second central axis C2.

[0056] Hereinafter, the turn portion 12n that is closest to the second central axis C2 may be referred to as the turn portion 121. Also, the turn portion connected to the turn portion 121 may be referred to as the turn portion 122. In the following, when describing matters common to each of the turn portions 12n, they will basically be referred to as the turn portion 12n.

[0057] In this embodiment, the shape of second planar coil element 12 corresponds to the shape of first planar coil element 11. Specifically, when turn portion 11n goes around to form a rectangle as in the illustrated example, turn portion 12n also goes around to form a rectangle like turn portion 11n. Also, when turn portion 11n has a shape that goes around to form a circle, turn portion 12n may also go around to form a circle like turn portion 11n.

[0058] Here, in this embodiment, the first central axis C1 is determined as follows. First, linear virtual turn parts having a shape similar to that of the innermost turn part 111 are drawn in a spiral shape inward in the radial direction from the radially inner end of the innermost turn part 111. Then, drawing is continued until a virtual turn part that fits within a diameter of 1 cm can be drawn. Then, a line passing through a radially inner region of the virtual turn part 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 the first central axis C1. The second central axis C2 is also determined in the same manner as the first central axis C1. First, linear virtual turn parts having a shape similar to that of the innermost turn part 121 are drawn in a spiral shape inward in the radial direction from the radially inner end of the innermost turn part 121. Then, drawing is continued until a virtual turn part that fits within a diameter of 1 cm can be drawn. A line passing through a radially inner region of the imaginary turn portion that is within a diameter of 1 cm, in a direction perpendicular to the circumferential and radial directions of the spiral shape, is defined as a second center axis C2.

[0059] The radially inner end (end close to the first central axis C1) of the first planar coil element 11 is electrically connected to the radially inner end (end close to the second central axis C2) of the second planar coil element 12. The connection wiring portion 14 shown in FIG. 2 is a conductor and electrically connects the first planar coil element 11 and the second planar coil element 12 in series. When the first planar coil element 11 and the second planar coil element 12 are connected, the direction in which the first planar coil element 11 goes around from the end of the first planar coil element 11 that is not connected to the second planar coil element 12 (the radially outer end of the first planar coil element 11) to the end that is connected to the second planar coil element 12 is the same as the direction in which the second planar coil element 12 goes around from the end of the second planar coil element 12 that is connected to the first planar coil element 11 to the end that is not connected to the first planar coil element 11 (the radially outer end of the second planar coil element 12).

[0060] The illustrated connection wiring section 14 is formed integrally with the first planar coil element 11, for example. The connection wiring section 14 may be connected to the second planar coil element 12 by ultrasonic connection or the like. On the other hand, a radially outer end (an end farther from the first central axis C1) of the first planar coil element 11 is connected to a first connection terminal 51. Also, a radially outer end (an end farther from the second central axis C2) of the second planar coil element 12 is connected to a second connection terminal 52.

[0061] In the present embodiment, the first planar coil element 11 and the second planar coil element 12 are formed, for example, by punching a metal plate such as a copper plate or an aluminum plate into a spiral shape. However, the first planar coil element 11 and the second planar coil element 12 can also be formed by etching a metal foil such as a copper foil or an aluminum foil into a spiral shape.

[0062] The thicknesses of the first planar coil element 11 and the second planar coil element 12 (the thicknesses of the conductors 11E and 12E) are measured along the axial direction of the first planar coil element 11 and the second planar coil element 12. The thicknesses of the first planar coil element 11 and the second planar coil element 12 (the thicknesses of the conductors 11E and 12E) may be, for example, 0.1 mm or more and 1.0 mm or less, 0.2 mm or more and 0.7 mm or less, or 0.3 mm or more and 0.4 mm or less. The thicknesses of the first planar coil element 11 and the second planar coil element 12 (the thicknesses of the conductors 11E and 12E) may be, for example, 0.15 mm or more and 0.35 mm or less. The thickness of the first planar coil element 11 (the thickness of the conductor 11E) may be the same as the thickness of the second planar coil element 12, or may be smaller or larger than the thickness of the second planar coil element 12. In other words, the thickness of second planar coil element 12 (the thickness of conductor 12E) may be the same as the thickness of first planar coil element 11, or may be greater than or smaller than the thickness of first planar coil element 11.

[0063] The radius of first planar coil element 11 (the distance from first central axis C1 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. The aspect ratio of first planar coil element 11 (conductor 11E) having a rectangular cross-sectional shape is determined by dividing the line width (the radial width of each turn portion 11n) of first planar coil element 11 (conductor 11E) by the thickness of first planar coil element 11 (conductor 11E). The aspect ratio of first planar coil element 11 (conductor 11E) may be 2 or more and 12 or less, or may be 3 or more and 10 or less.

[0064] Similarly, the radius of the second planar coil element 12 (the distance from the 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. The aspect ratio of the second planar coil element 12 (conductor 12E) having a rectangular cross-sectional shape is determined by dividing the line width (the radial width of each turn portion 12n) of the second planar coil element 12 (conductor 12E) by the thickness of the second planar coil element 12 (conductor 12E). The aspect ratio of the second planar coil element 12 (conductor 12E) may be 2 or more and 12 or less, or may be 3 or more and 10 or less.

[0065] The thickness and line width of conductors 11E and 12E may be measured by measuring each portion of conductors 11E and 12E with a ruler or the like in a cross section obtained by cutting coil component 5 in the axial direction to expose conductors 11E and 12E, or by analyzing a cross section image. Also, first planar coil element 11 and second planar coil element 12 may be taken out of coil component 5, and the thicknesses of conductors 11E and 12E may be measured with a ruler, calipers, or the like.

[0066] First planar coil element 11 and second planar coil element 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 large, it will hinder the thinning of coil device 5.

[0067] The number of turns of coil 10 (the sum of number of turns T1 of first planar coil element 11 and number of turns T2 of second planar coil element 12) is determined in consideration of the performance required of coil component 5. More specifically, it is determined so that coil component 5 has an appropriate inductance. For example, when coil component 5 is applied to system S that wirelessly transmits power to an electric vehicle, it is desirable that the inductance of coil component 5 is about 35 Hz to 50 Hz. In this case, the number of turns of coil 10 is, for example, about 8 to 10. However, the number of turns of coil 10 is not limited to this. The number of turns of coil 10 may be, for example, 6 to 24.

[0068] Here, there is a demand for improving the manufacturing efficiency of the coil component 5. For this reason, improvements in the handleability of the members constituting the coil component 5 have been studied.

[0069] Considering such circumstances, in the present embodiment, the number of turns of each of planar coil elements 11 and 12 is determined so that the number of turns T2 of second planar coil element 12 is smaller than the number of turns T1 of first planar coil element 11. This can improve the ease of handling of second planar coil element 12. That is, compared with the case where first planar coil element 11 and second planar coil element 12 have the same number of turns, the number of turns T2 of second planar coil element 12 is reduced, and therefore handling of second planar coil element 12 becomes easier. In the illustrated example, the number of turns T1 of first planar coil element 11 is twice the number of turns T2 of second planar coil element 12. More specifically, in the illustrated example, the number of turns of coil 10 is about 8 to 10, and based on this, the number of turns T1 of first planar coil element 11 is 6, and the number of turns T2 of second planar coil element 12 is 3. In other words, the plurality of turn portions 11n are composed of six turn portions 111 to 116. The plurality of turn portions 12n are each made up of three turn portions 121-123.

[0070] In addition, in the illustrated example, the line width of the second planar coil element 12 is larger than the line width of the first planar coil element 11. This reduces the risk of the second planar coil element 12 being deformed when the second planar coil element 12 is handled. This improves the ease of handling of the second planar coil element 12. In addition, the electrical resistance of the second planar coil element 12 can be reduced. In particular, in the illustrated example, the line width of the second planar coil element 12 arranged to face the magnetic shield member 20 is more than twice the line width of the first planar coil element 11.

[0071] The present inventors have found that it is possible to prevent the Q value of the coil component 5 from being significantly lower than that of a coil component including a conventional coil having a similar number of turns by arranging the plurality of turn portions 111-116 of the first planar coil element 11 and the plurality of turn portions 121-123 of the second planar coil element 12 as follows: That is, when viewed in the axial direction, at least one of the plurality of turn portions 121-123 of the second planar coil element 12 overlaps with two or more of the plurality of turn portions 111-116 of the first planar coil element 11, and each gap between the plurality of turn portions 121-123 of the second planar coil element 12 overlaps with one of the gaps between the plurality of turn portions 111-116 of the first planar coil element 11, when viewed in the axial direction.

[0072] In the illustrated example, each turn portion 12n of the second planar coil element 12 is disposed so as to overlap two adjacent turn portions of the first planar coil element 11 when viewed in the axial direction. In the illustrated example, when viewed in the axial direction, the turn portion 121 overlaps with the turn portions 111 and 112. Also, when viewed in the axial direction, the turn portion 122 overlaps with the turn portions 113 and 114. Also, when viewed in the axial direction, the turn portion 123 overlaps with the turn portions 115 and 116.

[0073] In the illustrated example, when viewed in the axial direction, the gap between the turn portions 121 and 122 overlaps with the gap between the turn portions 112 and 113. When viewed in the axial direction, the gap between the turn portions 122 and 123 overlaps with the gap between the turn portions 114 and 115.

[0074] Furthermore, in the illustrated example, an edge of each turn portion 12n of the second planar coil element 12 overlaps an edge of any of the turn portions of the first planar coil element 11 when viewed in the axial direction. More specifically, an inner edge of each turn portion 12n of the second planar coil element 12 overlaps an inner edge of any of the turn portions of the first planar coil element 11. Also, an outer edge of each turn portion 12n of the second planar coil element 12 overlaps an outer edge of any of the turn portions of the first planar coil element 11. In the illustrated example, an inner edge of the turn portion 121 overlaps an inner edge of the turn portion 111. An outer edge of the turn portion 121 overlaps an outer edge of the turn portion 112. An inner edge of the turn portion 122 overlaps an inner edge of the turn portion 113. An outer edge of the turn portion 122 overlaps an outer edge of the turn portion 114. An inner edge of turn portion 123 overlaps with an inner edge of turn portion 115. An outer edge of turn portion 123 overlaps with an outer edge of turn portion .

[0075] The ratio between the number of turns T1 of the first planar coil element 11 and the number of turns T2 of the second planar coil element 12 is not limited to 2:1. For example, the ratio may be 3:1. Furthermore, the number of turns T1 of the first planar coil element 11 does not have to be an integer multiple of the number of turns T2 of the second planar coil element 12. For example, the number of turns T1 of the first planar coil element 11 may be 5, and the number of turns T2 of the second planar coil element 12 may be 3. In this case, the line width of some of the turn portions of the second planar coil element 12 may be different from the line width of the other turn portions so that each gap between the plurality of turn portions 121 to 123 of the second planar coil element 12 overlaps with one of the gaps between the plurality of turn portions of the first planar coil element 11 when viewed in the axial direction. For example, the width of each turn portion 12n of the second planar coil element 12 may be determined so that the turn portion 121 overlaps with the turn portion 111, the turn portion 122 overlaps with the turn portions 112 and 113, and the turn portion 123 overlaps with the turn portions 114 and 115.

[0076] The line width of the first planar coil element 11 (the conductor 11E), i.e., the radial width of each turn portion 11n, is not particularly limited. However, in consideration of being able to transmit power of 1 kW or more, preferably 5 kW or more, in a high-frequency current frequency band of, for example, 79 kHz to 90 kHz, the radial width of the turn portion 11n may be 2 mm to 20 mm, 2 mm to 16 mm, 2 mm to 12 mm, or 2 mm to 8 mm.

[0077] The line width of the second planar coil element 12 (the conductor 12E), i.e., the radial width (width in the radial direction) of each turn portion 12n, is not particularly limited either. However, the line width of each turn portion 12n of the second planar coil element 12 is determined so that each gap between the multiple turn portions 121-123 of the second planar coil element 12 overlaps with any of the gaps between the multiple turn portions 111-116 of the first planar coil element 11 when viewed in the axial direction.

[0078] (Magnetic shielding material) The magnetic shield member 20 is provided to suppress magnetic transmission and / or leakage magnetic field. The magnetic shield member 20 is a sheet-like member separate from the first planar coil element 11, the second planar coil element 12, and the holder 30. The magnetic shield member 20 being separate from the first planar coil element 11, the second planar coil element 12, and the holder 30 means that the magnetic shield member 20 is not integrated with the first planar coil element 11, the second planar coil element 12, and the holder 30. However, the magnetic shield member 20 and the holder 30 may be joined via an adhesive layer or the like. The magnetic shield member 20 is formed to a size that includes the first planar coil element 11 and the second planar coil element 12 in a planar view. The magnetic shield member 20 overlaps the first planar coil element 11, the second planar coil element 12, and the holder 30, and is in direct contact with a part of the holder 30 (a second interlayer portion 32 described later).

[0079] The magnetic shield member 20 in this embodiment has magnetism and includes or is made of a magnetic material. In the coil component 5, a magnetic field is generated when a current is supplied to the first planar coil element 11 and the second planar coil element 12. The magnetic field generated in the coil component 5 spreads in all directions with respect to the central axes C1 and C2 of the first planar coil element 11 and the second planar coil element 12. At this time, the magnetic shield member 20 has magnetism, so that the spreading magnetic flux lines can be oriented toward the central axes C1 and C2. In addition, the coil component 5 can be installed on a moving body, and in this case, if the magnetic field generated by the coil component 5 flows toward other moving body components, the moving body components may be adversely affected. In such a case, the magnetic shield member 20 can suppress the leakage magnetic field that does not contribute to the generation of the current.

[0080] The magnetic shield member 20 preferably includes a soft magnetic material or a nanocrystalline magnetic material. More specifically, the magnetic shield member 20 includes ferrite, preferably soft ferrite. In the present embodiment, the magnetic shield member 20 includes plate-shaped ferrite. More specifically, the magnetic shield member 20 is configured by arranging a plurality of plate-shaped ferrites in a sheet shape.

[0081] The relative permeability of the magnetic shield member 20 may be equal to or greater than 500, or equal to or greater than 1000. The relative permeability of the magnetic shield member 20 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.

[0082] (holding body) As described above, the holder 30 functions to maintain the gap between the first planar coil element 11 and the second planar coil element 12, and also to maintain the gap between the second planar coil element 12 and the magnetic shield member 20. In the present embodiment, the holder 30 also has a function of integrating the first planar coil element 11 and the second planar coil element 12. In detail, as shown in FIG. 3 , the holder 30 includes a first interlayer portion 31 disposed between the first planar coil element 11 and the second planar coil element 12, and a second interlayer portion 32 disposed between the second planar coil element 12 and the magnetic shield member 20.

[0083] In this embodiment, the first interlayer section 31 is joined to the first planar coil element 11 and the second planar coil element 12, and the second interlayer section 32 is joined to the second planar coil element 12. This integrates the first planar coil element 11, the second planar coil element 12, and the holder 30. In detail, the first interlayer section 31 fills the gaps between the turn sections 11n and 12n facing each other from the innermost turn sections 111 and 121 to the outermost turn sections 116 and 123 in the first planar coil element 11 and the second planar coil element 12. In addition, the second interlayer section 32 fills the gaps between all the turn sections 121 to 123 and the portions of the magnetic shield member 20 facing them from the innermost turn section 121 to the outermost turn section 123 in the second planar coil element 12.

[0084] In the illustrated example, the first interlayer section 31 also fills the gaps between the turn portions 111-116 of the first planar coil element 11. In the illustrated example, the second interlayer section 32 also fills the gaps between the turn portions 121-123 of the second planar coil element 12.

[0085] Moreover, the retainer 30 in this embodiment further includes an outer peripheral frame portion 33 located on the outer peripheral side of the first interlayer portion 31 and the second interlayer portion 32, and an inner peripheral core portion 34 located on the inner peripheral side of the first interlayer portion 31 and the second interlayer portion 32. The first interlayer portion 31 and the second interlayer portion 32 are connected to the outer peripheral frame portion 33 and are also connected to the inner peripheral core portion 34. As a result, the first interlayer portion 31, the second interlayer portion 32, the outer peripheral frame portion 33 and the inner peripheral core portion 34 are formed as an integral part.

[0086] Note that the holding body 30 may have the first interlayer portion 31 function only for the purpose of maintaining the gap between the first planar coil element 11 and the second planar coil element 12, and the second interlayer portion 32 function only for the purpose of maintaining the gap between the second planar coil element 12 and the magnetic shield member 20. In this case, it goes without saying that the first interlayer portion 31 does not have to be joined to the first planar coil element 11 and the second planar coil element 12, and the second interlayer portion 32 does not have to be joined to the second planar coil element 12. Also, the holding body 30 does not have to include the outer peripheral frame portion 33 and the inner peripheral core portion 34.

[0087] The holder 30 is insulating and contains a resin. The holder 30 may be formed of, for example, an insulating resin. The resin contained in the holder 30 is not particularly limited as long as it is non-magnetic and insulating. The holder 30 may contain, for example, polyethylene or polypropylene, or may be formed of, polyethylene or polypropylene. The holder 30 may also contain, for example, fiber-reinforced plastic, or may be formed of fiber-reinforced plastic. More specifically, the holder 30 may contain, or be formed of, glass fiber-reinforced polyamide. Note that the term "insulating" refers to a material having a volume resistivity of 10 10 This means that the resistance is Ω·m or more.

[0088] (Magnetic wall) The magnetic wall portion 40 extends in the axial direction as shown in Fig. 3. As can be seen from Figs. 2 and 3, the magnetic wall portion 40 extends along the gaps between the turn portions 111-116 of the first planar coil element 11 as viewed in the axial direction. In the illustrated example, the magnetic wall portion 40 has a spiral shape and overlaps with the gaps between the turn portions 111-116 of the first planar coil element 11 as viewed in the axial direction.

[0089] The magnetic wall portion 40 has magnetism, and suppresses eddy current loss and leakage flux, and increases the coupling coefficient, thereby improving coil performance. The relative permeability of the magnetic wall portion 40 is preferably 2.0 or more, and may be 2.0 or more and 20.0 or less. The relative permeability of the magnetic wall portion 40 is more preferably 5.0 or more, and may be 5.0 or more and 20.0 or less. The relative permeability of the magnetic wall portion 40 is not particularly limited, but if it is too large, the flexibility and strength of the magnetic wall portion 40 may be undesirably impaired. Therefore, the relative permeability of the magnetic wall portion 40 may be 200 or less.

[0090] 3, the magnetic wall portion 40 is disposed opposite the second surface 11b of the first planar coil element 11. In the illustrated example, the magnetic wall portion 40 is disposed on the same plane as the second surface 11b. The height (dimension along the axial direction) of the magnetic wall portion 40 is not particularly limited, but may be, for example, 0.5 mm or more, or 1.0 mm or more.

[0091] The magnetic wall 40 in the present embodiment includes, for example, a holding material containing a resin and a plurality or an infinite number of magnetic particles made of a magnetic material. The magnetic particles are held by the holding material. The holding material is insulating, specifically, non-magnetic and insulating. The holding material is not particularly limited, and may include, for example, polyethylene or polypropylene, or may be formed from polyethylene or polypropylene. The holding material may include, for example, fiber reinforced plastic, or may be formed from fiber reinforced plastic. More specifically, the holding material may include, or be formed from glass fiber reinforced polyamide.

[0092] The magnetic particles may be formed from any one or more of ferrite, particularly soft magnetic material ferrite, nanocrystalline magnetic material, silicon steel, soft magnetic iron, and amorphous metal.

[0093] (Connection terminal) 2 and 4, the first connection terminal 51 is connected to a radially outer end of the turn portion 116 of the first planar coil element 11. The second connection terminal 52 is connected to a radially outer end of the turn portion 123 of the second planar coil element 12. The first connection terminal 51 and the second connection terminal 52 can be used, for example, when connecting to the high-frequency current supply unit 1A or the conversion unit 2A. The connection between the first connection terminal 51 and the turn portion 116 and the connection between the second connection terminal 52 and the turn portion 123 may be performed by ultrasonic bonding. However, the connection method is not limited, and for example, a connection using a conductive adhesive may be adopted.

[0094] <Modification> Various modifications can be made to the above-described embodiment. Modifications of this embodiment will be described below with reference to Figs.

[0095] For example, the magnetic wall portion 40 may extend along the axial direction from one side to the other side of the first planar coil element 11 through gaps between the plurality of turn portions 111-116 of the first planar coil element 11. In this case, the holder 30 may be formed with a slit 36 ​​for receiving the magnetic wall portion 40.

[0096] 6 to 8, second planar coil element 12 may have long holes 12h extending along the plurality of turn portions 121 to 123 of second planar coil element 12. In this case, due to the skin effect, more current can flow through second planar coil element 12. In the illustrated example, long holes 12h extend along the spiral shape of second planar coil element 12.

[0097] 6 and 8, when the long hole 12h is formed in the second planar coil element 12, the long hole 12h may overlap with any of the gaps between the turn portions 111 to 116 of the first planar coil element 11 as viewed in the axial direction. In this case, the magnetic wall portion 40 may extend into the long hole 12h of the second planar coil element 12, as shown in FIG.

[0098] 9 to 11, the first planar coil element 11 may be disposed facing the magnetic shield member 20. In other words, the first planar coil element 11 may be disposed between the second planar coil element 12 and the magnetic shield member 20. In this case, the fourth surface 12b of the second planar coil element 12 forms the front side surface 10b of the coil 10. In addition, the second surface 11b of the first planar coil element 11 forms the back side surface 10a of the coil 10. In this case, the magnetic wall portion 40 may extend along the gaps between the turn portions 121 to 123 of the second planar coil element 12 as viewed in the axial direction. In the example shown in FIG. 9 and FIG. 11, the magnetic wall portion 40 overlaps with the gaps between the turn portions 121 to 123 of the second planar coil element 12 as viewed in the axial direction. The magnetic wall portion 40 may be disposed facing the fourth surface 12b of the second planar coil element 12 as shown in FIG. 9. 9, the magnetic wall portion 40 is disposed on the same plane as the fourth surface 12b. Alternatively, as shown in FIG 11, the magnetic wall portion 40 may extend axially from one side to the other side of the second planar coil element 12 through gaps between the turn portions 121-123 of the second planar coil element 12.

[0099] In addition, when the first planar coil element 11 is disposed facing the magnetic shield member 20, the second planar coil element 12 may have a long hole 12h extending along the turn portions 121 to 123 of the second planar coil element 12, as shown in FIGS. 12 to 15. In this case, the coil component 5 may further include an additional magnetic wall portion 45. The additional magnetic wall portion 45 extends along the axial direction. The additional magnetic wall portion 45 extends along the long hole 12h as viewed in the axial direction. In the example shown in FIGS. 12 to 15, the additional magnetic wall portion 45 overlaps with the long hole 12h as viewed in the axial direction. The additional magnetic wall portion 45 may be disposed facing the fourth surface 12b of the second planar coil element 12, as shown in FIGS. 12 to 14. In the example shown in FIGS. 12 and 13, the additional magnetic wall portion 45 is disposed on the same plane as the fourth surface 12b. 15 , the additional magnetic wall portion 45 may extend axially from one side to the other side of the second planar coil element 12 through a long hole 12h formed in the plurality of turn portions 121-123 of the second planar coil element 12. In this case, a slit 37 for receiving the additional magnetic wall portion 45 may be formed in the holder 30.

[0100] <Applications of coil components> The coil component 5 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.

[0101] When the coil component 5 is used as a power transmission coil, the first connection terminal 51 and the second connection terminal 52 are connected to the high frequency current supply unit 1A or the AC power supply as shown in Fig. 1. When a high frequency current is supplied to the coil component 5, the current can be passed from the first connection terminal 51 to the planar coil element 11, and then from the second connection terminal 52 to the high frequency current supply unit 1A or the AC power supply. Also, the current can be passed from the second connection terminal 52 to the planar coil element 11, and then from the first connection terminal 51 to the high frequency current supply unit 1A or the AC power supply. This makes it possible to generate a magnetic field including magnetic lines of force along the central axis C of the planar coil element 11.

[0102] On the other hand, when the coil component 5 is used as a receiving coil, a high-frequency current can be generated in the planar coil element 11 by receiving or generating a magnetic field including magnetic lines of force that pass through the inside of the planar coil element 11. Then, this high-frequency current can be supplied to an external device from the first connection terminal 51 or the second connection terminal 52.

[0103] The coil component 5 can also be used in a transformer, an antenna, etc. For example, when the coil component 5 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 element 11 to the iron core.

[0104] <Simulation for evaluating the performance of coil component 5> Simulations performed to evaluate the performance of coil components 5, 5', 5'', 5''' and 5'''' according to Examples 1 to 4 and Comparative Examples 1 to 6 will be described below. The simulations were performed using Femtet (registered trademark) manufactured by Murata Software Corporation.

[0105] The common conditions for the simulations of Examples 1 to 4 and Comparative Examples 1 to 6 are as follows. The high frequency current supplied is 40A and the frequency is 85KHz. The first planar coil element 11 and the second planar coil elements 12, 12', 12'' are made of copper. The dimension of the gap between first planar coil element 11 and second planar coil elements 12, 12', 12'', 12''' is 0.50 mm, and the dimension of the gap between coils 10, 10', 10'', 10'''' and magnetic shield member 20 is 1.0 mm. The magnetic shield member 20 has a relative magnetic permeability of 3,000. The magnetic wall portion 40 is disposed on the same plane as the front side surfaces 10b, 10b', 10b'', and 10b'' of the coils 10, 10', 10'', and 10'''. The relative magnetic permeability of the magnetic wall portion 40 is 5.0.

[0106] The common conditions for the simulations in Examples 1 to 4 are as follows. The number of turns T1 of first planar coil element 11 is six, and the number of turns T2 of second planar coil element 12 is three. The line width of first planar coil element 11 is 9 mm, and the line width of second planar coil element 12 is 22 mm. When viewed in the axial direction, the inner edge of turn portion 121 overlaps with the inner edge of turn portion 111. When viewed in the axial direction, the outer edge of turn portion 121 overlaps with the outer edge of turn portion 112. When viewed in the axial direction, the inner edge of turn portion 122 overlaps with the inner edge of turn portion 113. When viewed in the axial direction, the outer edge of turn portion 122 overlaps with the outer edge of turn portion 114. When viewed in the axial direction, the inner edge of turn portion 123 overlaps with the inner edge of turn portion 115. When viewed in the axial direction, the outer edge of turn portion 123 overlaps with the outer edge of turn portion 116.

[0107] The individual conditions in the simulations of Examples 1 to 4 and Comparative Examples 1 to 4 are as follows. <Example 1> 2 to 4, in coil component 5 of Example 1, magnetic shield member 20 is disposed opposite second planar coil element 12. First planar coil element 11 has a thickness of 0.25 mm, and second planar coil element 12 has a thickness of 0.5 mm. Magnetic wall portion 40 extends along and overlaps with gaps between multiple turn portions 111-116 of first planar coil element 11 as viewed in the axial direction. <Example 2> In the coil component 5 of the second embodiment, similarly to the examples shown in Figs. 6 and 7, the magnetic shield member 20 is disposed facing the second planar coil element 12. The second planar coil element 12 has a long hole 12h extending along the spiral shape of the second planar coil element 12. When viewed in the axial direction, the long hole 12h overlaps with the gap between the turn portions 111 and 112, the gap between the turn portions 113 and 114, and the gap between the turn portions 115 and 116. The width of the long hole 12h along the radial direction is 9 mm. The other configurations are the same as those of the first embodiment. <Example 3> In coil device 5 of Example 3, similarly to the example shown in FIGS. 9 and 10, magnetic shield member 20 is disposed facing first planar coil element 11. First planar coil element 11 has a thickness of 0.5 mm, and second planar coil element 12 has a thickness of 02.5 mm. Magnetic wall portion 40 is disposed facing fourth surface 12b of second planar coil element 12. Magnetic wall portion 40 extends along and overlaps with gaps between multiple turn portions 121-123 of second planar coil element 12 when viewed in the axial direction. The other configurations are the same as those of Example 1. <Example 4> In the coil component 5 of the fourth embodiment, similarly to the examples shown in FIGS. 12 to 14, the magnetic shield member 20 is disposed facing the second planar coil element 12. The first planar coil element 11 has a thickness of 0.25 mm, and the second planar coil element 12 has a thickness of 0.5 mm. The second planar coil element 12 has a long hole 12h extending along the spiral shape of the second planar coil element 12. The long hole 12h overlaps with the gap between the turn portions 111 and 112, the gap between the turn portions 113 and 114, and the gap between the turn portions 115 and 116, as viewed in the axial direction. The long hole 12h has a width of 9 mm along the radial direction. An additional magnetic wall portion 45 is disposed facing the fourth surface 12b of the second planar coil element 12. The additional magnetic wall portion 45 extends along the long hole 12h as viewed in the axial direction, and overlaps with the long hole 12h. The relative permeability of the additional magnetic wall portion 45 is 5.0. The other configurations are the same as those of the third embodiment. <Comparative Example 1> In the conventional coil device 5' of Comparative Example 1, as shown in FIG. 16, the magnetic shield member 20 is disposed facing the second planar coil element 12'. The first planar coil element 11' has four turn portions 111 to 114. The second planar coil element 12' has four turn portions 121 to 124. That is, the number of turns T1 of the first planar coil element 11 and the number of turns T2 of the second planar coil element 12' are both 4. The line widths of the first planar coil element 11' and the second planar coil element 12' are both 14 mm. When viewed in the axial direction, both edges of the turn portion 121 overlap with both edges of the turn portion 111. When viewed in the axial direction, both edges of the turn portion 122 overlap with both edges of the turn portion 112. When viewed in the axial direction, both edges of the turn portion 123 overlap with both edges of the turn portion 113. Moreover, when viewed in the axial direction, both edge portions of the turn portion 124 overlap both edge portions of the turn portion 114. The other configurations are the same as those in the first embodiment. <Comparative Example 2> In conventional coil device 5' of Comparative Example 2, first planar coil element 11' and second planar coil element 12' each have a line width of 10 mm. <Comparative Example 3> In conventional coil device 5' of Comparative Example 3, first planar coil element 11' and second planar coil element 12' each have a line width of 8 mm. <Comparative Example 4> In a conventional coil device 5'' of Comparative Example 4, as shown in FIG. 17, a magnetic shield member 20 is disposed facing a second planar coil element 12''. The first planar coil element 11 has six turn portions 111 to 116. The second planar coil element 12'' has six turn portions 121 to 126. That is, the number of turns T1 of the first planar coil element 11 and the number of turns T2 of the second planar coil element 12'' are both 6. The line width of the second planar coil element 12'' is 9 mm. When viewed in the axial direction, both edges of the turn portion 121 overlap with both edges of the turn portion 111. When viewed in the axial direction, both edges of the turn portion 122 overlap with both edges of the turn portion 112. When viewed in the axial direction, both edges of the turn portion 123 overlap with both edges of the turn portion 113. Moreover, when viewed in the axial direction, both edges of turn portion 124 overlap with both edges of turn portion 114. Moreover, when viewed in the axial direction, both edges of turn portion 125 overlap with both edges of turn portion 115. Moreover, when viewed in the axial direction, both edges of turn portion 126 overlap with both edges of turn portion 116. The other configurations are the same as in Example 1. <Comparative Example 5> In coil device 5''' of Comparative Example 5, as shown in FIG. 18, magnetic shield member 20 is disposed facing second planar coil element 12'. First planar coil element 11 has six turn portions 111-116. Second planar coil element 12' has four turn portions 121-124. That is, the number of turns T1 of first planar coil element 11 is 6, and the number of turns T2 of second planar coil element 12' is 4. Second planar coil element 12' has a line width of 14 mm. When viewed in the axial direction, the gaps between the plurality of turn portions 121-124 of second planar coil element 12' do not overlap any of the gaps between the plurality of turn portions 111-116 of first planar coil element 11. The other configurations are similar to those of Example 1. <Comparative Example 6> In the coil device 5'''' of Comparative Example 6, as shown in FIG. 19, the magnetic shield member 20 is disposed facing the first planar coil element 11. The first planar coil element 11 has a thickness of 0.5 mm, and the second planar coil element 12 has a thickness of 0.25 mm. The magnetic wall portion 40 extends along the gaps between the turn portions 121-124 of the second planar coil element 12' when viewed in the axial direction. The magnetic wall portion 40 extends along the gaps between the turn portions 121-124 of the second planar coil element 12' when viewed in the axial direction, and overlaps with the gaps. The other configurations are the same as those of Comparative Example 5.

[0108] Simulation results are shown in Fig. 20 and Fig. 21. As can be seen from Fig. 20 and Fig. 21, even if the number of turns T2 of second planar coil element 12 is made smaller than the number of turns T1 of first planar coil element 11, as long as each gap between the plurality of turn portions 121-123 of second planar coil element 12 overlaps with any of the gaps between the plurality of turn portions 111-116 of first planar coil element 11, the Q value of coil device 5 does not decrease significantly compared to coil devices 5' of Comparative Examples 2 and 3 including conventional coil 10' having the same line width of first planar coil element 11 and the same number of coil turns.

[0109] The coil component 5 according to the embodiment and its modification described above includes a coil 10 including a first planar coil element 11 and a second planar coil element 12. The first planar coil element 11 and the second planar coil element 12 each have a spiral shape having a plurality of turn portions 111-116 and 121-123. The first planar coil element 11 and the second planar coil element 12 are arranged facing each other in an axial direction extending on central axes C1 and C2 of the spiral shape. The first planar coil element 11 and the second planar coil element 12 are connected in series with each other. The number of turns T2 of the second planar coil element 12 is smaller than the number of turns T1 of the first planar coil element 11. Also, when viewed in the axial direction, at least one of the plurality of turn portions 121-123 of the second planar coil element 12 overlaps with two or more of the plurality of turn portions 111-116 of the first planar coil element 11. Moreover, when viewed in the axial direction, each gap between the plurality of turn portions 121-123 of the second planar coil element 12 overlaps with one of the gaps between the plurality of turn portions 111-116 of the first planar coil element 111. Such coil component 5 can improve the handleability of the second planar coil element 12, thereby improving the manufacturing efficiency of the coil component. Furthermore, there is a low risk of the Q value of coil component 5 being significantly reduced, as compared with coil component 5' having a conventional coil 10' in which the line width of first planar coil element 11 is approximately the same and the number of coil turns is approximately the same.

[0110] In coil component 5 according to the embodiment and its modification, number of turns T1 of first planar coil element 11 is twice number of turns T2 of second planar coil element 12. When viewed in the axial direction, each turn portion 121, 122, and 123 of second planar coil element 12 overlaps two turn portions 111, 112, 123, 124, and 125, 126 of first planar coil element 11. Such coil component 5 is easy to design.

[0111] In coil device 5 according to the embodiment and its modification, when viewed in the axial direction, the inner edge of each of turn portions 121, 122, and 123 of second planar coil element 12 overlaps with the inner edge of any of turn portions 111, 113, and 114 of first planar coil element 11. Also, the outer edge of each of turn portions 121, 122, and 123 of second planar coil element 12 overlaps with the outer edge of any of turn portions 112, 114, and 116 of the first planar coil element.

[0112] In coil component 5 according to the modified example, long holes 12h extending along turn portions 121-123 are formed in multiple turn portions 121-123 of second planar coil element 12. This allows more current to flow through second planar coil element 12.

[0113] In coil device 5 according to the modified example, slot 12h extends along the spiral shape of second planar coil element 12.

[0114] In coil device 5 according to the modified example, slot 12h overlaps with any of the gaps between the plurality of turn portions 111-116 of first planar coil element 11 when viewed in the axial direction.

[0115] In coil device 5 according to the embodiment and its variations, second planar coil element 12 has a thickness of 0.15 mm or more and 0.35 mm or less. When second planar coil element 12 has such a small thickness, the handleability of second planar coil element 12 is significantly improved by reducing number of turns T2 of second planar coil element 12.

[0116] Coil device 5 according to the embodiment and its modified example further includes magnetic shield member 20 disposed opposite second planar coil element 12. In this case, the performance of coil device 5 can be improved.

[0117] In the embodiment and the modified example in which the second planar coil element 12 is disposed facing the magnetic shield member 20, the coil device 5 further includes a magnetic wall portion 40 extending along the axial direction and extending along gaps between the plurality of turn portions 111-116 of the first planar coil element 11 as viewed in the axial direction. The magnetic wall portion 40 is disposed facing a second surface 11b of the first planar coil element 11 opposite to a first surface 11a facing the second planar coil element 12. In this case, the performance of the coil device 5 can be further improved.

[0118] In a modification in which the second planar coil element 12 is disposed facing the magnetic shield member 20, the coil component 5 further includes a magnetic wall portion 40 extending along the axial direction and extending along the gaps between the turn portions 111-116 of the first planar coil element 11 as viewed in the axial direction. The magnetic wall portion 40 extends along the axial direction from one side to the other side of the first planar coil element 11 through the gaps between the turn portions 111-116 of the first planar coil element 11. In this case, the performance of the coil component 5 can be further improved.

[0119] Coil device 5 according to the modified example further includes a magnetic shield member 20 disposed opposite first planar coil element 11. In this case as well, the performance of coil device 5 can be improved.

[0120] In a modification in which the first planar coil element 11 is disposed facing the magnetic shield member 20, the coil component 5 further includes a magnetic wall portion 40 extending along the axial direction and extending along gaps between the plurality of turn portions 121-123 of the second planar coil element 12 as viewed in the axial direction. The magnetic wall portion 40 is disposed facing a fourth surface 12b of the second planar coil element 12 opposite to a third surface 12a facing the first planar coil element 11. In this case, the performance of the coil component 5 can be further improved.

[0121] In a modification in which the first planar coil element 11 is disposed facing the magnetic shield member 20, the coil component 5 further includes a magnetic wall portion 40 extending along the axial direction and extending along the gaps between the turn portions 121-123 of the second planar coil element 12 as viewed in the axial direction. The magnetic wall portion 40 extends along the axial direction from one side to the other side of the second planar coil element 12 through the gaps between the turn portions 121-123 of the second planar coil element 12. In this case, the performance of the coil component 5 can be further improved.

[0122] In a modification in which the first planar coil element 11 is disposed facing the magnetic shield member 20, a long hole 12h extending along the turn portions 121-123 of the second planar coil element 12 is formed in the plurality of turn portions 121-123. The coil component 5 further includes an additional magnetic wall portion 45. The additional magnetic wall portion 45 extends along the axial direction and extends along the long hole 12h as viewed in the axial direction. The additional magnetic wall portion 45 is disposed facing a fourth surface 12b of the second planar coil element 12 opposite to a third surface 12a facing the first planar coil element 11. In this case, the performance of the coil component 5 can be further improved.

[0123] In a modification in which the first planar coil element 11 is disposed facing the magnetic shield member 20, the coil component 5 has a long hole 12h formed in the plurality of turn portions 121-123 of the second planar coil element 12, the long hole 12h extending along the turn portions 121-123. The coil component 5 further includes an additional magnetic wall portion 45. The additional magnetic wall portion 45 extends along the axial direction and extends along the long hole 12h as viewed in the axial direction. The additional magnetic wall portion 45 passes through the long hole 12h formed in the plurality of turn portions 121-123 of the second planar coil element 12 and extends along the axial direction from one side to the other side of the second planar coil element 12. In this case, the performance of the coil component 5 can be further improved.

[0124] Although several modifications to the above-mentioned embodiment have been described, it is of course possible to apply a plurality of modifications in appropriate combination. [Explanation of symbols]

[0125] S…Power transmission system 1...Power transmission device 1A…High frequency current supply 2...Power receiving device 2A…Conversion section 5, 5', 5'', 5''', 5''''... Coil parts 10, 10', 10''... coil 11, 11'...first planar coil element 11a…First page 11b…Second side 11E…Conductor 12, 12', 12''...second planar coil element 12a...Side 3 12b...Side 4 12h…long hole 12E…Conductor 20...Magnetic shielding material 30...Holding body 40...Magnetic wall part 45…Additional magnetic wall 51…First connection terminal 52…Second connection terminal C1…First central axis line C2…Second central axis line

Claims

1. a coil including a first planar coil element and a second planar coil element each having a spiral shape with a plurality of turns, the first planar coil element and the second planar coil element being arranged opposite each other in an axial direction extending along a central axis of the spiral shape and being connected in series with each other; the number of turns of the second planar coil element is less than the number of turns of the first planar coil element, When viewed in the axial direction, at least one of the plurality of turn portions of the second planar coil element overlaps with two or more of the plurality of turn portions of the first planar coil element; a coil component in which, when viewed in the axial direction, each gap between the plurality of turn portions of the second planar coil element overlaps with any one of the gaps between the plurality of turn portions of the first planar coil element.

2. a number of turns of the first planar coil element is twice the number of turns of the second planar coil element; The coil component according to claim 1 , wherein each turn portion of the second planar coil element overlaps two turn portions of the first planar coil element when viewed in the axial direction.

3. 2. The coil component according to claim 1, wherein, when viewed in the axial direction, an inner edge of each turn portion of the second planar coil element overlaps an inner edge of any turn portion of the first planar coil element, and an outer edge of each turn portion of the second planar coil element overlaps an outer edge of any turn portion of the first planar coil element.

4. The coil component according to claim 1 , wherein the second planar coil element has a plurality of turn portions each having a slot formed therein and extending along the turn portions.

5. The coil component according to claim 4 , wherein the slot extends along the spiral shape of the second planar coil element.

6. The coil component according to claim 4 , wherein the long hole overlaps any one of the gaps between the plurality of turn portions of the first planar coil element when viewed in the axial direction.

7. The coil component according to claim 1 , wherein the second planar coil element has a thickness of 0.15 mm or more and 0.35 mm or less.

8. The coil component according to claim 1 , further comprising a magnetic shield member disposed opposite the second planar coil element.

9. a magnetic wall portion extending along the axial direction and extending along gaps between the plurality of turn portions of the first planar coil element as viewed in the axial direction, The coil component according to claim 8 , wherein the magnetic wall portion is disposed to face a second surface of the first planar coil element opposite a first surface facing the second planar coil element.

10. a magnetic wall portion extending along the axial direction and extending along gaps between the plurality of turn portions of the first planar coil element as viewed in the axial direction, 9. The coil component according to claim 8, wherein the magnetic wall portion extends along the axial direction from one side to the other side of the first planar coil element through gaps between a plurality of turns of the first planar coil element.

11. The coil component according to claim 1 , further comprising a magnetic shield member disposed opposite the first planar coil element.

12. a magnetic wall portion extending along the axial direction and extending along gaps between the plurality of turn portions of the second planar coil element as viewed in the axial direction, The coil component according to claim 11 , wherein the magnetic wall portion is disposed to face a fourth surface of the second planar coil element opposite a third surface facing the first planar coil element.

13. a magnetic wall portion extending along the axial direction and extending along gaps between the plurality of turn portions of the second planar coil element as viewed in the axial direction, 12. The coil component according to claim 11, wherein the magnetic wall portion extends along the axial direction from one side to the other side of the second planar coil element through gaps between a plurality of turns of the second planar coil element.

14. a long hole is formed in each of the plurality of turn portions of the second planar coil element, the long hole extending along the turn portion; The coil component further includes an additional magnetic wall portion, The additional magnetic wall portion extends along the axial direction and extends along the long hole when viewed in the axial direction, The coil component according to claim 11 , wherein the additional magnetic wall portion is disposed to face a fourth surface of the second planar coil element opposite a third surface facing the first planar coil element.

15. a long hole is formed in each of the plurality of turn portions of the second planar coil element, the long hole extending along the turn portions; The coil component further includes an additional magnetic wall portion, The additional magnetic wall portion extends along the axial direction and extends along the long hole when viewed in the axial direction, 12. The coil component according to claim 11, wherein the additional magnetic wall portion extends along the axial direction from one side to the other side of the second planar coil element through the long hole formed in a plurality of turns of the second planar coil element.

16. A power transmitting device comprising the coil component according to claim 1.

17. A power receiving device comprising the coil component according to claim 1.

18. A mobile object comprising the power receiving device according to claim 17.

19. 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 .

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