Coil unit, power transmission device, power reception device, power transmission system, and movable body

Abstract

To provide a coil unit, a power transmission device, a power reception device, a power transmission system, and a movable body that achieve reduction in the thickness of the coil unit and efficient power transmission.SOLUTION: In a wireless power transmission system, a coil unit 5 comprises: a coil 10 that is formed spirally around a central axis C; a first shield member 20 that has a front side face 20a facing the coil and a rear side face 20b being a surface on the opposite side of the front side face; and a second shield member 30 that is arranged facing the front side face of the first shield member on the radial outside and / or the radial inside of the coil 1, which are laminated in this order in a third direction D3. The first shield member and the second shield member have magnetism. The first shield member is divided into a plurality of first small pieces 20P. When seen in an axial direction, the adjacent first small pieces of the first shield member have a gap G formed therebetween. The second shield member at least partially overlaps the gaps of the first shield member when seen in the axial direction.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] In recent years, wireless power transmission systems that transmit power from a power transmitting device to a power receiving device in a non-contact manner have become widespread. Patent Document 1 discloses a coil unit used in a power transmitting device and a power receiving device of a wireless power transmission system. The coil unit includes a coil formed in a spiral shape. When power is supplied to the coil of the power transmitting device, a magnetic field is generated around the coil. Due to the effect of this magnetic field, a current flows in the coil of the power receiving device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-27112 Summary of the Invention [Problem to be solved by the invention]

[0004] In such a wireless power transmission system, it is desirable to improve the performance of the coil unit to perform efficient power transmission, and at the same time, it is desirable to make the coil unit thinner and lighter.

[0005] An object of the present disclosure is to achieve a thinner coil unit and efficient power transmission. [Means for solving the problem]

[0006] One embodiment of the present disclosure relates to the following [1] to

[15] .

[0007] [1] A coil formed in a spiral shape around a central axis; A first shield member having a front side surface facing the coil and a back side surface opposite to the front side surface; A second shield member disposed radially outward and / or inward of the coil so as to face the front surface of the first shield member; Equipped with the first shield member and the second shield member are magnetic, The first shield member is divided into a plurality of first small pieces, A gap is formed between adjacent first small pieces of the first shield member when viewed in the axial direction, A coil unit, wherein, when viewed in the axial direction, the second shield member overlaps at least a portion of the gap of the first shield member.

[0008] [2] The coil unit described in [1], wherein the second shielding member is arranged radially outward of the coil and covers at least 80% or more of the gap existing outside the coil when viewed in the axial direction.

[0009] [3] The coil unit according to [1] or [2], wherein the second shielding member is arranged radially inward of the coil and covers at least 80% or more of the gap existing inside the coil when viewed in the axial direction.

[0010] [4] The coil unit according to any one of [1] to [3], wherein the first shielding member and the second shielding member contain ferrite.

[0011] [5] The coil unit according to any one of [1] to [4], wherein the first shielding member and the second shielding member have a relative magnetic permeability of 500 or more.

[0012] [6] a third shield member disposed opposite the rear surface of the first shield member, The coil unit according to any one of [1] to [5], wherein the distance between the coil and the third shield member is 30 mm or less.

[0013] [7] a third shield member disposed opposite the rear surface of the first shield member, The coil unit according to any one of [1] to [6], wherein the distance between the first shielding member and the third shielding member is 25 mm or less.

[0014] [8] The coil includes a group of straight portions that are arranged in a radial direction and extend in one direction, The coil unit according to any one of [1] to [7], wherein at least a part of the gap extends linearly and crosses at least a part of the group of linear portions when viewed in the axial direction.

[0015] [9] The coil unit according to [8], wherein when viewed in the axial direction, an angle formed between the straight portion and at least a portion of the gap is greater than or equal to 80° and less than or equal to 100°.

[0016]

[10] The coil includes a group of curved portions including a plurality of curved portions arranged in a radial direction and extending along a circumferential direction, The coil unit according to any one of [1] to [7], wherein at least a portion of the gap extends linearly and crosses at least a portion of the group of curved portions when viewed in the axial direction.

[0017]

[11] The coil unit according to

[10] , wherein when viewed in the axial direction, an angle formed between a tangent to the curved portion and at least a portion of the gap is greater than or equal to 80° and less than or equal to 100°.

[0018]

[12] A power transmitting device comprising the coil unit according to any one of [1] to

[11] .

[0019]

[13] A power receiving device comprising the coil unit according to any one of [1] to

[11] .

[0020]

[14] 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 is provided with the coil unit according to any one of [1] to

[11] .

[0021]

[15] A moving body comprising the coil unit according to any one of [1] to

[11] . Effect of the Invention

[0022] According to an embodiment of the present disclosure, a thinner coil unit and efficient power transmission can be achieved. [Brief description of the drawings]

[0023] [Figure 1] FIG. 1 is a diagram that illustrates a schematic diagram of a wireless power transmission system to which a coil unit according to an embodiment of the present disclosure can be applied. [Diagram 2] FIG. 2 is a perspective view of a coil unit according to an embodiment. [Diagram 3] FIG. 3 is a cross-sectional view of the carp unit taken along line III-III in FIG. [Figure 4] FIG. 4 is a plan view of the coil unit shown in FIG. [Diagram 5] FIG. 5 is a plan view corresponding to FIG. 4, showing a modified example of the coil unit. [Figure 6] FIG. 6 is a table showing the measurement results of Example 1 and Comparative Example 1. [Figure 7] FIG. 7 is a cross-sectional view showing the configuration of the power transmission coil unit of Example 2 and Comparative Example 2. As shown in FIG. [Figure 8] FIG. 8 is a table showing the maximum transmission efficiencies of Example 2 and Comparative Example 2.

[0024] An embodiment will be described below with reference to the drawings. In the drawings accompanying this specification, the scale and aspect ratios have been appropriately changed and exaggerated from those of the actual objects for the convenience of illustration and understanding.

[0025] 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.

[0026] 1 is a schematic diagram of a wireless power transmission system S to which a coil unit 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.

[0027] <Wireless power transmission system> The power transmission system S includes a power transmitting device 1 and a power receiving device 2. The power transmitting device 1 includes a coil unit 5 and a high-frequency current supplying unit 1A. The coil unit 5 in the power transmitting device 1 functions as a power transmitting coil unit. The high-frequency current supplying unit 1A supplies a high-frequency current to the coil unit 5 serving as a power transmitting coil unit.

[0028] The power receiving device 2 includes a coil unit 5 and a conversion unit 2A. The coil unit 5 in the power receiving device 2 functions as a power receiving coil unit. The conversion unit 2A shapes a high-frequency current generated in the coil unit 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.

[0029] In this embodiment, each of the power transmitting device 1 and the power receiving device 2 includes a coil unit 5. However, the coil unit 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 unit may be used in the other.

[0030] 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 unit 5 serving as a power transmitting coil unit. At this time, a magnetic field is generated in the coil unit 5 by electromagnetic induction. Then, due to the influence of this magnetic field, a high-frequency current is generated in the coil unit 5 serving as a power receiving coil unit 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.

[0031] The power transmission system S shown in Fig. 1 employs a magnetic resonance method as a power transmission method. However, the coil unit 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.

[0032] 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 unit 5 is not limited to wireless power transmission systems. For example, the coil unit 5 may be used in transformers, DC-DC converters, antennas, and the like.

[0033] The coil unit 5 according to this embodiment will be described below.

[0034] <Coil unit> The coil unit 5 according to this embodiment will be described below. Fig. 2 is a perspective view of the coil unit 5. Fig. 3 is a cross-sectional view taken along line III-III of the coil unit 5 shown in Fig. 2. Fig. 4 is a plan view of the coil unit 5 shown in Fig. 2. However, in Fig. 4, a thermally conductive layer 50 and an insulating layer 55, which will be described later, are omitted. In Fig. 4, a coil 10 and a second shield member 30, which will be described later, are hatched to facilitate understanding, but these hatches do not indicate cross sections of the coil 10 and the second shield member 30.

[0035] 2 and 3, the coil unit 5 includes a coil 10, a first shielding member 20, and a second shielding member 30. In the illustrated example, the coil unit 5 further includes a third shielding member 40, a thermally conductive layer 50, an insulating layer 55, a first connecting terminal 61, and a second connecting terminal 62. As shown in Fig. 3, the third shielding member 40, the insulating layer 55, the first shielding member 20, the thermally conductive layer 50, the coil 10, and the second shielding member 30 are layered in this order in a third direction D3.

[0036] The coil unit 5 and its components each have a front side surface facing the third direction D3 and a back side surface opposite to the front side surface. The coil 10 has a back side surface 10b facing the first shield member 20 and a front side surface 10a opposite to the back side surface 10b. The terms "front side" and "back side" used for the coil unit 5 and its components respectively mean the side facing in the same direction as the front side surface 10a and the side facing in the same direction as the back side surface 10b. In the example shown in FIG. 2 to FIG. 4, the coil 10 forms the front side surface of the coil unit 5, and the third shield member 40 forms the back side surface of the coil unit 5.

[0037] (coil) The coil 10 has a spiral shape as shown in Figures 2 and 4. The coil 10 is made of a conductive material. In the illustrated example, the coil 10 includes copper. Specifically, the coil 10 is made of copper. However, the coil 10 may be made of a copper alloy, aluminum, an aluminum alloy, or the like.

[0038] The coil 10 has a plate shape. As shown in Fig. 3, the cross-sectional shape of the coil 10 in a direction perpendicular to the direction in which the coil 10 winds in a spiral shape is rectangular.

[0039] The symbol C shown in Figs. 2 to 4 indicates the central axis of the coil 10. The central axis C passes through the center of the spiral shape of the coil 10. In other words, the coil 10 is formed to have a spiral shape around the central axis C. In addition, the spiral shape in this disclosure means a planar curve shape wound in a spiral shape. The planar curve here also includes a planar pattern that repeatedly goes around 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 turns (or approaches the center as it turns).

[0040] Hereinafter, "axial direction" refers to a direction extending on the central axis C or a direction parallel to the central axis C. The above-mentioned third direction D3 is a direction along the axial direction. Moreover, "radial direction" refers to the radial direction of a circle drawn on a plane perpendicular to the central axis C with an arbitrary point on the central axis C as its center. Moreover, the radial inward direction of the coil 10 and the turn portions 10n constituting the coil 10 refers to a direction approaching the central axis C in the radial direction. Moreover, the radial outward direction of the coil 10 and the turn portions 10n refers to a direction away from the central axis C in the radial direction.

[0041] The coil 10 has a conductor 10E having a spiral shape formed by a plurality of turn portions 10n. The plurality of turn portions 10n of the coil 10 are arranged in a direction perpendicular to the central axis C of the spiral shape. More specifically, the plurality of turn portions 10n are connected so as to gradually move away from the central axis C of the spiral shape in a radially outward direction. This forms the spiral shape.

[0042] The turn portion 10n is basically a shape in which a linear conductor portion does not form a ring but turns 360 degrees around the central axis C. In the case of a so-called planar coil, both ends of the turn portion 10n are shifted in the radial direction. In the multiple turn portions 10n, a radially outer end of a certain turn portion 10n is connected to a radially inner end of another turn portion 10n, and the other turn portions 10n extend so as to move away from the central axis C. In the illustrated example, the coil 10 has turn portions 101 to 108. Of the multiple turn portions 10n, the one closest to the central axis C is the turn portion 101. Of the multiple turn portions 10n, the one furthest from the central axis C is the turn portion 108. In the following, when describing matters common to each of the multiple turn portions 10n, they are basically referred to as turn portions 10n.

[0043] In the illustrated example, the turn portion 10n goes around to form a quadrangle as a whole, but the turn portion 10n may have a polygonal shape other than a quadrangle (e.g., a hexagonal shape, an octagonal shape, or a dodecagonal shape) or may go around to form a circle.

[0044] Here, in the present disclosure, the central axis C is determined as follows. First, linear imaginary turn portions similar in shape to the innermost turn portion 101 are drawn in sequence from the radially inner end of the innermost turn portion 101 to form a spiral shape radially inward. Drawing is continued until a virtual turn portion that fits within a diameter of 1 cm is drawn. Then, a line that passes through the radially inner region of the imaginary 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 the central axis C.

[0045] As described above, in the illustrated example, the turn portion 10n goes around to form a quadrangle as a whole. Each turn portion 10n has first to fourth straight portions 11 to 14. The first to fourth straight portions 11 to 14 are connected in this order along the circumferential direction of a circle centered on the central axis C. The first straight portion 11 and the third straight portion 13 extend along a first direction D1. The second straight portion 12 and the fourth straight portion 14 extend along a second direction D2. The first direction D1 and the second direction D2 are directions along a plane perpendicular to the axial direction. The second direction D2 is a direction intersecting the first direction D1. In the illustrated example, the second direction D2 is perpendicular to the first direction D1, but is not limited thereto.

[0046] The first straight portions 11 of the plurality of turn portions 101-108 form a first straight portion group 11F. The second straight portions 12 of the plurality of turn portions 101-108 form a second straight portion group 12F. The third straight portions 13 of the plurality of turn portions 101-108 form a third straight portion group 13F. The fourth straight portions 14 of the plurality of turn portions 101-108 form a fourth straight portion group 14F.

[0047] A central axis C is located between the first straight line group 11F and the third straight line group 13F. A central axis C is located between the second straight line group 12F and the fourth straight line group 14F. The second straight line group 12F is located between one end of the first straight line group 11F and one end of the third straight line group 13F. The fourth straight line group 14F is located between the other end of the first straight line group 11F and the other end of the third straight line group 13F.

[0048] In the illustrated example, the straight line portions 11, 12; 12, 13; 13, 14; 14, 11 adjacent in the circumferential direction are connected by first to fourth curved portions 15-18 that curve along the circumferential direction, respectively. The first curved portions 15 of the plurality of turn portions 101-108 form a first curved portion group 15F. The second curved portions 16 of the plurality of turn portions 101-108 form a second curved portion group 16F. The third curved portions 17 of the plurality of turn portions 101-108 form a third curved portion group 17F. The fourth curved portions 18 of the plurality of turn portions 101-108 form a fourth curved portion group 18F.

[0049] As an example, the coil 10 is formed by punching a metal plate such as a copper plate or an aluminum plate into a spiral shape. However, the coil 10 can also be formed by etching a metal foil such as a copper foil or an aluminum foil into a spiral shape.

[0050] The thickness of the coil 10 (the thickness of the conductor 10E) is measured along the axial direction of the coil 10. The thickness of the coil 10 (the thickness of the conductor 10E) 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.

[0051] The radius of coil 10 (the distance from the central axis C to the farthest point 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 coil 10 (conductor 10E) having a rectangular cross-sectional shape is determined by dividing the line width (radial width) of coil 10 (conductor 10E) by the thickness of coil 10 (conductor 10E). The aspect ratio of coil 10 (conductor 10E) may be 2 or more and 12 or less, or may be 3 or more and 10 or less.

[0052] The thickness of the conductor 10E may be measured by measuring each part of the conductor 10E with a ruler or the like in a cross section obtained by cutting the coil unit 5 in the axial direction to expose the conductor 10E, or by analyzing a cross section image. Alternatively, the coil 10 may be removed from the coil unit 5, and the thickness of the conductor 10E may be measured with a ruler, calipers, or the like. Similarly, the dimensions of other parts of the coil unit 5 may be measured by measuring the cross section with a ruler or the like, or by analyzing a cross section image.

[0053] (First shielding member) The first shield member 20 is provided to suppress the transmission of a magnetic field and / or leakage of a magnetic field. The first shield member 20 is disposed on the rear side of the coil 10. The first shield member 20 is provided between the third shield member 40 and the coil 10.

[0054] The first shielding member 20 is formed in a flat plate shape overall, and extends along a plane perpendicular to the axial direction of the coil 10. The first shielding member 20 is sized such that an outer edge 20e is located outside the coil 10 when viewed in the axial direction. A front side surface 20a of the first shielding member 20 faces the coil 10. A back side surface 20b of the first shielding member 20 faces the third shielding member 40.

[0055] The first shield member 20 includes a magnetic material. As a result, the first shield member 20 can orient the magnetic field (magnetic lines of force) that are generated in the coil 10 so as to spread in all directions relative to the central axis C toward the central axis C. This can increase the magnetic efficiency of the coil unit 5. In addition, the first shield member 20 can prevent the magnetic lines of force from reaching peripheral components. In other words, the first shield member 20 suppresses leakage magnetic fields that do not contribute to the generation of current.

[0056] The first shield member 20 preferably includes a soft magnetic material. More specifically, the first shield member 20 includes a ferrite, preferably a soft ferrite. The first shield member 20 may also include a nanocrystalline magnetic material.

[0057] The relative permeability of the first shield member 20 may be equal to or greater than 500, or may be equal to or greater than 1000. The relative permeability of the first shield member 20 may be equal to or greater than 500 and equal to or less than 3000, or may be equal to or greater than 1000 and equal to or less than 3000. Note that the relative permeability in this disclosure is a value measured at a frequency of 85 kHz and an environmental temperature of 23 degrees.

[0058] In the illustrated example, the first shielding member 20 is divided into a plurality of first small pieces 20P. In other words, the first shielding member 20 includes a plurality of first small pieces 20P arranged in the same plane. The dimensions of each of the first small pieces 20P as viewed in the axial direction may be 150 mm or less × 150 mm or less. By configuring the first shielding member 20 from a plurality of first small pieces 20P, it becomes easier to form a first shielding member 20 with large dimensions.

[0059] In the illustrated example, each of the first small pieces 20P has a triangular or rectangular planar shape, but is not limited thereto. The planar shape of the first small pieces 20P can be any shape, such as a polygonal shape other than a triangular or rectangular shape, or a circular shape.

[0060] A gap G is formed between adjacent first small pieces 20P, 20P. The width of the gap G is arbitrary, but considering the manufacturing tolerance of the first small pieces 20P, the width of the gap G is preferably 1 mm or more. Furthermore, from the viewpoint of suppressing the transmission of magnetic lines through the gap G, the width of the gap G is preferably 6 mm or less.

[0061] In the illustrated example, a part of the gap G formed in the first shield member 20 extends linearly and crosses at least a part of the first straight portion group 11F. In other words, the gap G does not extend parallel to the first straight portion 11. This prevents the magnetic field lines formed around the first straight portion 11 from reaching the third shield member 40 through the gap G. This prevents the magnetic field lines formed around the first straight portion 11 from generating eddy currents in the third shield member 40. This contributes to further improving the magnetic efficiency of the coil unit 5.

[0062] Similarly, in the illustrated example, another part of the gap G formed in the first shield member 20 extends linearly and crosses at least a part of the second to fourth straight portion groups 12F-14F. This prevents the magnetic field lines formed around the second to fourth straight portion groups 12-14 from reaching the third shield member 40 through the gap G. This prevents the magnetic field lines formed around the second to fourth straight portion groups 12-14 from generating eddy currents in the third shield member 40. This contributes to further improving the magnetic efficiency of the coil unit 5.

[0063] When viewed in the axial direction, the angle formed by the first to fourth straight portions 11-14 and the gap G intersecting the straight portions 11-14 may be, for example, 80° to 100°. In this case, it is possible to effectively prevent eddy currents from being generated in the third shield member 40 due to magnetic field lines formed around the first to fourth straight portions 11-14. In the illustrated example, the angle formed by the first to fourth straight portions 11-14 and the gap G intersecting the straight portions 11-14 is 90°. In this case, it is possible to more effectively prevent eddy currents from being generated in the third shield member 40 due to magnetic field lines formed around the first to fourth straight portions 11-14.

[0064] In the illustrated example, a portion of the gap G formed in the first shield member 20 extends linearly and crosses at least a portion of the first curved portion group 15F. In other words, the gap G does not extend parallel to the first curved portion 15. This prevents the magnetic field lines formed around the first curved portion 15 from reaching the third shield member 40 through the gap G. This makes it possible to prevent eddy currents from being generated in the third shield member 40 by the magnetic field lines formed around the first curved portion 15.

[0065] Similarly, in the illustrated example, another portion of the gap G formed in the first shield member 20 extends linearly and crosses at least a portion of the second to fourth curved portion groups 16F-18F. This prevents the magnetic field lines formed around the second to fourth curved portion groups 16F-18F from reaching the third shield member 40 through the gap G. This prevents the magnetic field lines formed around the second to fourth curved portion groups 16F-18F from generating eddy currents in the third shield member 40.

[0066] When viewed in the axial direction, the angle between the tangents L15-L18 of the first to fourth curved portions 15-18 and the gap G intersecting the curved portions 15-18 may be, for example, 80° to 100°. In this case, it is possible to effectively prevent eddy currents from being generated in the third shield member 40 due to the magnetic field lines formed around the first to fourth curved portions 15-18. In the illustrated example, the angle between the tangents L15-L18 of the first to fourth curved portions 15-18 and the gap G intersecting the curved portions 15-18 is 90°. In this case, it is possible to more effectively prevent eddy currents from being generated in the third shield member 40 due to the magnetic field lines formed around the first to fourth curved portions 15-18.

[0067] Of course, the manner in which the first shielding member 20 is divided is not limited to the above. For example, the first shielding member 20 may be divided as shown in Fig. 5. As shown in Fig. 5, a part of the gap G of the first shielding member 20 may extend parallel to any one of the first to fourth straight portions 11 to 14 of the coil 10 when viewed in the axial direction.

[0068] In the illustrated example, gap G includes a portion that extends outward from coil 10 and a portion that extends inward from coil 10 when viewed in the axial direction. Hereinafter, the portion of gap G that extends outward from coil 10 is also referred to as "outer gap GO." Additionally, the portion of gap G that extends inward from coil 10 is also referred to as "inner gap GI."

[0069] The thickness of the first shield member 20 is arbitrary, but is, for example, 0.01 mm or more, preferably 1 mm or more, and more preferably 3 mm or more. When the thickness of the first shield member 20 is 0.01 mm or more, thermal deformation of the first shield member 20 due to the heat of the coil 10 is suppressed.

[0070] The distance between the first shield member 20 and the coil 10 is arbitrary, but is, for example, 1 mm or less, preferably 0.7 mm or less, and more preferably 0.5 mm or less, which allows the coil unit 5 to be effectively made thinner.

[0071] (Second shielding member) The second shield member 30 is also provided to suppress the transmission of a magnetic field and / or leakage of a magnetic field. In particular, the second shield member 30 is provided to suppress the transmission of a magnetic field through the gap G of the first shield member 20.

[0072] The second shield member 30 includes a magnetic material. When viewed in the axial direction, the second shield member 30 is disposed radially outward and / or inward of the coil 10. When viewed in the axial direction, the second shield member 30 overlaps at least a portion of the gap G of the first shield member 20. This makes it possible to suppress the transmission of magnetic field lines through the gap G. Therefore, the magnetic efficiency of the coil unit 5 can be further improved.

[0073] The second shield member 30 is not disposed at a position overlapping with the coil 10 when viewed in the axial direction. This makes it possible to suppress an increase in the weight of the coil unit 5 due to the inclusion of the second shield member 30 in the coil unit 5. Therefore, it is possible to achieve both improved magnetic efficiency and reduced weight of the coil unit 5.

[0074] The second shield member 30 is disposed facing the front side surface 20a of the first shield member 20. In other words, the second shield member 30 is disposed on the front side of the first shield member 20. The second shield member 30 is disposed on the radially outer side and / or inner side of the coil 10. In other words, as shown in FIG. 3, the side surface of the second shield member 30 faces the side surface of the coil 10 in the radial direction. In further words, the second shield member 30 is disposed at the same axial position as the coil 10. This makes it possible to suppress an increase in the thickness of the coil unit 5 due to the inclusion of the second shield member 30 in the coil unit 5. Therefore, it is possible to achieve both an improvement in magnetic efficiency and a reduction in thickness of the coil unit 5.

[0075] In the illustrated example, the second shield member 30 includes a plurality of second small pieces 30P. Each second small piece 30P is generally formed in a flat plate shape and extends along a plane perpendicular to the axial direction of the coil 10. Some of the plurality of second small pieces 30P are disposed radially outward of the coil 10. Other parts of the plurality of second small pieces 30P are disposed radially inward of the coil 10. Hereinafter, the second small pieces 30P disposed radially outward of the coil 10 among the plurality of second small pieces 30P are also referred to as "second outer small pieces 30PO". In addition, the second small pieces 30P disposed radially inward of the coil 10 among the plurality of second small pieces 30P are also referred to as "second inner small pieces 30PI".

[0076] The second outer piece 30PO overlaps at least a portion of the outer gap GO when viewed in the axial direction. The second outer piece 30PO covers at least 80% of the outer gap GO that is present outside the coil 10 when viewed in the axial direction. This makes it possible to effectively suppress the transmission of magnetic lines of force through the outer gap GO.

[0077] The second inner piece 30PI overlaps at least a portion of the inner gap GI when viewed in the axial direction. The second inner piece 30PI covers at least 80% of the inner gap GI that exists inside the coil 10 when viewed in the axial direction. This makes it possible to effectively suppress the transmission of magnetic lines through the inner gap GI.

[0078] Each second small piece 30P can also orient the magnetic field (magnetic lines of force) that is generated in the coil 10 so as to spread in all directions relative to the central axis C toward the central axis C. This can increase the magnetic efficiency of the coil unit 5. The second small pieces 30P can also prevent the magnetic lines of force from reaching surrounding components. In other words, the second small pieces 30P also suppress leakage magnetic fields that do not contribute to the generation of current.

[0079] In the illustrated example, each second small piece 30P has a triangular or rectangular planar shape, but is not limited thereto. The planar shape of the second small pieces 30P can be any shape, such as a polygonal shape other than a triangular or rectangular shape, or a circular shape.

[0080] The thickness of the second shield member 30 is arbitrary, but is, for example, 0.01 mm or more, preferably 1 mm or more, and more preferably 3 mm or more. When the thickness of the second shield member 30 is 0.01 mm or more, thermal deformation of the second shield member 30 due to the heat of the coil 10 is suppressed.

[0081] 3, the rear surface of the second shielding member 30 is flush with the rear surface 10b of the coil 10, but is not limited to this. The rear surface of the second shielding member 30 may be closer to the first shielding member 20 than the rear surface 10b of the coil 10, or may be farther away from the first shielding member 20.

[0082] 3, the second shield member 30 protrudes in the third direction D3 beyond the front side surface 10a of the coil 10. This allows the second shield member 30 to effectively orient the magnetic field (magnetic lines of force) that is generated in the coil 10 so as to spread in all directions relative to the central axis C, toward the central axis C.

[0083] Of course, the second shield member 30 does not have to protrude in the third direction D3 beyond the front side surface 10a of the coil 10. The front side surface of the second shield member 30 may be flush with the front side surface 10a of the coil 10. Furthermore, the coil 10 may protrude in the third direction D3 beyond the front side surface of the second shield member 30.

[0084] The second shield member 30 preferably includes a soft magnetic material. More specifically, the second shield member 30 includes a ferrite, preferably a soft ferrite. The second shield member 30 may also include a nanocrystalline magnetic material. The second shield member 30 may be formed of the same material as the first shield member 20.

[0085] The relative magnetic permeability of the second shield member 30 may be equal to or greater than 500, or may be equal to or greater than 1000. The relative magnetic permeability of the second shield member may be equal to or greater than 500 and equal to or less than 3000, or may be equal to or greater than 1000 and equal to or less than 3000.

[0086] The distance between the second shield member 30 and the first shield member 20 is arbitrary, but is preferably, for example, 1 mm or more. By making the distance between the second shield member 30 and the first shield member 20 1 mm or more, it is possible to suppress the occurrence of discharge between the second shield member 30 and the first shield member 20. Note that, by disposing a highly insulating layer between the second shield member 30 and the first shield member 20, it is possible to suppress the occurrence of discharge between the second shield member 30 and the first shield member 20 even if the distance between the second shield member 30 and the first shield member 20 is less than 1 mm.

[0087] (Third shielding component) The third shielding member 40 is disposed on the rear side of the first shielding member 20. In other words, the third shielding member 40 is disposed facing the rear side surface 20b of the first shielding member 20. The third shielding member 40 shields the electromagnetic waves generated in the coil 10 from the rear side. The electromagnetic waves generated in the coil 10 are blocked by the third shielding member 40, so that the electromagnetic waves can be prevented from affecting other electronic components, the human body, and the like. The material for forming the third shielding member 40 may be a metal such as aluminum. When the coil unit 5 is attached to an automobile, the third shielding member 40 may be a metal plate that constitutes the body of the automobile.

[0088] In the illustrated example, the third shield member 40 is formed in a flat plate shape overall, and extends along a plane perpendicular to the axial direction of the coil 10. The third shield member 40 has a size such that an outer edge 40e thereof is positioned outside the coil 10 when viewed in the axial direction.

[0089] The thickness of the third shield member 40 is arbitrary, but is, for example, 1 mm or more, and preferably 2 mm or more.

[0090] The distance between the third shield member 40 and the coil 10 is arbitrary, but is, for example, 30 mm or less, preferably 20 mm or less, and more preferably 10 mm or less. The distance between the third shield member 40 and the first shield member 20 is arbitrary, but is, for example, 25 mm or less, preferably 15 mm or less, and more preferably 5 mm or less. This allows the coil unit 5 to be effectively made thinner.

[0091] (Thermal Conduction Layer) 2 and 3, a thermally conductive layer 50 is disposed between the coil 10 and the first shield member 20 and between the second shield member 30 and the first shield member 20. The first shield member 20 is heated by the heat of the coil 10. The thermally conductive layer 50 can promote heat dissipation from the first shield member 20. In the illustrated example, the thermally conductive layer 50 is in contact with the first shield member 20.

[0092] The thermally conductive layer 50 is formed in a sheet shape. When viewed in the axial direction, the thermally conductive layer 50 extends continuously from the inside to the outside of the coil 10. In other words, when viewed in the axial direction, the thermally conductive layer 50 has a size such that its outer edge 50e is located outside the coil 10. With such a thermally conductive layer 50, the heat of the first shielding member 20 is dispersed in the planar direction of the thermally conductive layer 50, and the temperature gradient in the planar direction of the first shielding member 20 can be reduced. In particular, in the illustrated example, the first shielding member 20 is divided into a plurality of first small pieces 20P. Since the thermally conductive layer 50 extends continuously, the heat of the first small pieces 20P can be moved along the planar direction of the thermally conductive layer 50. As a result, it is possible to suppress the risk that some of the first small pieces 20P are maintained at a high temperature.

[0093] The thermally conductive layer 50 is preferably made of an insulating material, which can prevent electrical connection between the first shield member 20 and other members (for example, the coil 10 and the second shield member 30).

[0094] The material for forming the thermally conductive layer 50 may be, for example, "COOL PROVIDE (registered trademark) CPSH" or "COOL PROVIDE (registered trademark) CPVG-2" manufactured by Kitagawa Industries Co., Ltd. Alternatively, the thermally conductive layer 50 may be formed using, for example, an insulating heat dissipation material prepared by dispersing a thermally conductive filler in an insulating resin.

[0095] (insulating layer) 2 and 3, an insulating layer 55 is disposed between the first shielding member 20 and the third shielding member 40. This makes it possible to prevent electrical connection between the first shielding member 20 and the third shielding member 40.

[0096] In the illustrated example, the insulating layer 55 is formed in a sheet shape. In this example, the insulating layer 55 has a size that covers the thermally conductive layer 50 when viewed in the axial direction. The insulating layer 55 does not have to be formed in a sheet shape. For example, the insulating layer 55 may be composed of a plurality of insulating members formed in a block shape. In this case, the plurality of insulating members may be spaced apart from each other. Even with such an insulating layer 55, the distance between the first shielding member 20 and the third shielding member 40 can be maintained at a predetermined distance, and electrical connection between the first shielding member 20 and the third shielding member 40 can be prevented.

[0097] The insulating layer 55 may have thermal conductivity. In this case, the insulating layer 55 can promote heat dissipation from the coil unit 5. In this case, the insulating layer 55 may be made of the same material as the thermally conductive layer 50.

[0098] (Connection terminal) As shown in FIG. 2, the first connection terminal 61 and the second connection terminal 62 are connected to the outer end and the inner end in the radial direction of the coil 10, respectively. More specifically, the first connection terminal 61 is connected to the turn portion 108, and the second connection terminal 62 is connected to the turn portion 101. The first connection terminal 61 and the second connection terminal 62 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 61 and the turn portion 108 and the connection between the second connection terminal 62 and the turn portion 101 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.

[0099] When the coil unit 5 is used as the power transmission coil unit, the first connection terminal 61 and the second connection terminal 62 are connected to the high frequency current supply unit 1A or the AC power supply as shown in Fig. 1. When a current is supplied to the coil 10 from the high frequency current supply unit 1A or the AC power supply, a magnetic field including magnetic lines of force along the central axis C is generated in the coil 10.

[0100] On the other hand, when the coil unit 5 is used as the power receiving coil unit, the first connection terminal 61 and the second connection terminal 62 are connected to the conversion unit 2A as shown in Fig. 1. When the coil 10 is subjected to a magnetic field including magnetic field lines along the central axis C, a high-frequency current is generated in the coil 10. Then, this high-frequency current can be supplied from the first connection terminal 61 or the second connection terminal 62 to the conversion unit 2A or a battery.

[0101] <Coil unit applications> The coil unit 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.

[0102] When the coil unit 5 is used as a power transmission coil, the first connection terminal 61 and the second connection terminal 62 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 unit 5, the current can be passed from the first connection terminal 61 to the coil 10, and then from the second connection terminal 62 to the high frequency current supply unit 1A or the AC power supply. Also, the current can be passed from the second connection terminal 62 to the coil 10, and then from the first connection terminal 61 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 coil 10.

[0103] On the other hand, when the coil unit 5 is used as a receiving coil, a high-frequency current can be generated in the coil 10 by receiving or generating a magnetic field including magnetic lines of force that pass through the inside of the coil 10. Then, this high-frequency current can be supplied to an external device from the first connection terminal 61 or the second connection terminal 62.

[0104] The coil unit 5 can also be used in a transformer, an antenna, etc. For example, when the coil unit 5 functions as a primary coil in a transformer, the first connection terminal 61 and the second connection terminal 62 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 coil 10 to the iron core.

[0105] Next, the difference in performance of the coil unit 5 depending on whether or not the second shield member 30 is present will be described.

[0106] <Example 1> As the coil unit 5 of Example 1, a first coil unit 5a and a second coil unit 5b were prepared. The first coil unit 5a was configured in the same manner as the coil unit 5 shown in Figure 5, and included a spirally formed coil 10, a first shielding member 20, a second shielding member 30, a third shielding member 40, a thermally conductive layer 50, and an insulating layer 55. The second coil unit 5b differed from the first coil unit 5a in that it did not include the third shield member 40 and the insulating layer 55. In other respects, the second coil unit 5b was similar to the first coil unit 5a. The coil 10 in the first and second coil units 5a was made of copper, had a line width of 6 mm, and a thickness of 0.5 mm. The dimensions of the coil 10 along the first direction D1 and the second direction D2 were 296 mm and 296 mm, respectively. The first shielding member 20 was formed by dividing it into ten first small pieces 20P. Each first small piece 20P was a ferrite plate. The width of the gap G between adjacent first small pieces 20P, 20P was 1 mm. The dimensions of the first shielding member 20 in the first direction D1 and the second direction D2 were 360 ​​mm and 360 mm, respectively. The thickness of the first shielding member 20 was 3 mm. In addition, the distance between the first shielding member 20 and the coil 10 was 1 mm. The second shielding member 30 included eight second small pieces 30P. Each second small piece 30P was a ferrite plate. One of the eight second small pieces 30P was disposed inside the coil 10. The other second small pieces 30P were disposed outside the coil 10. The second small pieces 30P disposed inside the coil 10 covered 80% of the gap G present inside the coil 10 when viewed in the axial direction. The second small pieces 30P disposed outside the coil 10 covered 80% of the gap G present outside the coil 10 when viewed in the axial direction. The thickness of the second shielding member 30 was 3 mm. The back side of the second shielding member 30 was flush with the back side 10b of the coil 10. The third shielding member 40 was made of aluminum. The dimensions of the third shielding member 40 in the first direction D1 and the second direction D2 were 400 mm and 400 mm, respectively. The thickness of the third shielding member 40 was 2 mm. The distance between the first shielding member 20 and the third shielding member 40 was 0.5 mm. The thermally conductive layer 50 was formed using "Cool Provide (registered trademark) CPSH" manufactured by Kitagawa Industries Co., Ltd. The thermally conductive layer 50 had a thickness of 2 mm. The insulating layer 55 was a plastic sheet and had a thickness of 0.5 mm.

[0107] <Comparative Example 1> As the coil unit 205 of Comparative Example 1, a third coil unit 205a and a fourth coil unit 205b were prepared. The third coil unit 205a differed from the first coil unit 5a in that it did not include the second shield member 30. In other respects, the third coil unit 205a was similar to the first coil unit 5a. The fourth coil unit 205b differed from the second coil unit 5b in that it did not include the second shield member 30. In other respects, the fourth coil unit 205b was similar to the second coil unit 5b.

[0108] (Rating 1) Next, a high-frequency current of 85 kHz was applied to the coils 10 of the first coil unit 5a, the second coil unit 5b, the third coil unit 205a, and the fourth coil unit 205b thus fabricated, and the Q value, inductance (L), and impedance (Z) of each of the coil units 5a, 5b, 205a, and 205b were measured. The measurement results are shown in FIG. 6.

[0109] As can be seen from FIG. 6, when comparing the third coil unit 205a and the fourth coil unit 205b, the Q value of the third coil unit 205a was 26% lower than the Q value of the fourth coil unit 205b. On the other hand, when comparing the first coil unit 5a and the second coil unit 5b, the Q value of the first coil unit 5a was only 13% lower than the Q value of the second coil unit 5b. The difference between the third coil unit 205a and the fourth coil unit 205b is that the former has the third shielding member 40, whereas the latter does not have the third shielding member 40. The difference between the first coil unit 5a and the second coil unit 5b is that the former has the third shielding member 40, whereas the latter does not have the third shielding member 40. Also, the difference between the first coil unit 5a and the third coil unit 205a is that the former has the second shielding member 30 while the latter does not have the second shielding member 30. Also, the difference between the second coil unit 5b and the fourth coil unit 205b is that the former has the second shielding member 30 while the latter does not have the second shielding member 30.

[0110] 6, it can be seen that in the coil unit of Comparative Example 1, the presence of the third shield member 40 reduces the Q value by 26%, whereas in the coil unit 5 of Example 1, the presence of the third shield member 40 reduces the Q value by only 13%. From this, it can be seen that in the coil unit 5 of Example 1, the presence of the second shield member 30 prevents the magnetic field generated in the coil 10 from reaching the third shield member 40.

[0111] Example 2 Next, the first coil unit 5a of the first embodiment is used as a power receiving coil unit, and the maximum transmission efficiency value (η max More specifically, the power transmission coil unit was configured as shown in the "Configuration of the Power Transmission Coil Unit" below, and the maximum transmission efficiency value (η maxIn both cases, the receiving coil unit was connected to an LCR meter "Agilent 4248A" manufactured by Agilent Technologies, and the inductance and impedance were measured at a measurement frequency of 85 kHz. The inductance was measured using the inductance (L open ) and inductance in SHORT compensation mode (L sc ) was measured.

[0112] <Configuration of power transmission coil unit> 7, the power transmitting coil unit 305 has a coil 310, a first shielding member 320, a second shielding member 330, a third shielding member 340, and a heat dissipation sheet 360. The third shielding member 340, the heat dissipation sheet 360, the second shielding member 330, the first shielding member 320, and the coil 310 are layered in this order in a direction along the central axis of the coil 310. The coil 310 was made of a litz wire. The coil 310 was formed in a spiral shape around the central axis 300C. The litz wire was made by twisting together 1600 enameled wires having a diameter of 0.05 mm. The coil 310 was produced by winding the litz wire so that a coil element having 10 turns was laminated in one layer in the axial direction. The thickness (diameter) of the litz wire was 3.5 mm. The dimensions of the coil 310 along the first direction D1 and the second direction D2 were 500 mm and 650 mm, respectively. The first shielding member 320 was a ferrite plate. The dimensions of the first shielding member 320 in the first direction D1 and the second direction D2 were 600 mm and 700 mm, respectively. The thickness of the first shielding member 320 was 3 mm. The distance between the first shielding member 320 and the coil 10 was 2 mm. The second shielding member 330 was a ferrite plate. The dimensions of the second shielding member 330 in the first direction D1 and the second direction D2 were 600 mm and 700 mm, respectively. The thickness of the second shielding member 330 was 3 mm. In addition, the distance between the second shielding member 330 and the first shielding member 320 was 2 mm. The heat dissipation sheet 360 was made of aluminum. The dimensions of the heat dissipation sheet 360 in the first direction D1 and the second direction D2 were 600 mm and 700 mm, respectively. The thickness of the third shielding member 40 was 35 mm. The distance between the heat dissipation sheet 360 and the second shielding member 330 was 2 mm. The third shield member 340 was made of aluminum. The dimensions of the third shield member 340 in the first direction D1 and the second direction D2 were 680 mm and 750 mm, respectively. The thickness of the third shield member 340 was 5 mm. The distance between the third shield member 340 and the heat dissipation sheet 360 was 0.5 mm.

[0113] <Three cases> Case 1 The distance between the power receiving coil unit and the power transmitting coil unit in the third direction D3 is 120 mm. The central axis C of the coil of the power receiving coil unit coincides with the central axis 300C of the coil of the power transmitting coil unit. Second Case The distance between the receiving coil unit and the transmitting coil unit is 150 mm. The central axis C of the coil of the power receiving coil unit is shifted from the central axis 300C of the coil of the power transmitting coil unit by 75 mm in the first direction D1 and by 100 mm in the second direction D2. Case 3 The distance between the power receiving coil unit and the power transmitting coil unit is 250 mm. The central axis C of the coil of the power receiving coil unit is shifted from the central axis 300C of the coil of the power transmitting coil unit by 75 mm in the first direction D1 and by 100 mm in the second direction D2.

[0114] In addition, the maximum transmission efficiency value (η max ) is a theoretical value calculated using the following formula:

number

number

[0115] Comparative Example 2 In addition, the first coil unit 205a of Comparative Example 1 was used as a power receiving coil unit, and the maximum transmission efficiency value (η max The configuration of the power transmission coil unit was the same as that of the power transmission coil unit used in Example 2. The maximum transmission efficiency value (η max The method for determining was the same as in Example 2.

[0116] (Rating 2) FIG. 8 shows the maximum transmission efficiency values ​​(η max 8, X and Y respectively denote the distance between the central axis C of the power receiving coil unit 5a, 205a and the central axis 300C of the power transmitting coil unit along the first direction D1 and the second direction D2. Also, in FIG. 8, Z denotes the distance between the power receiving coil unit 5a, 205a and the power transmitting coil unit along the axial direction.

[0117] As can be seen from FIG. 8, in all of the first to third cases, the maximum transmission efficiency value (η max ) is the maximum transmission efficiency value (η max In particular, in the third case (i.e., when the central axis C of the power receiving coil unit is offset from the central axis 300C of the power transmitting coil unit) in which the distance between the power receiving coil unit and the power transmitting coil unit is large, the maximum transmission efficiency value (η max ) is the maximum transmission efficiency value (η max ) is significantly higher than that.

[0118] The coil unit 5 according to the embodiment and the modified example thereof described above includes a coil 10, a first shielding member 20, and a second shielding member 30. The coil 10 is formed in a spiral shape around an arbitrary central axis C. The first shielding member 20 has a front side surface 20a facing the coil 10 and a back side surface 20b that is the surface opposite to the front side surface 20a. The second shielding member 30 is disposed radially outward and / or inward of the coil 10, facing the front side surface 20a of the first shielding member 20. The first shielding member 20 and the second shielding member 30 are magnetic. The first shielding member 20 is divided into a plurality of first small pieces 20P. When viewed in the axial direction, a gap G is formed between the adjacent first small pieces 20P, 20P of the first shielding member 20. When viewed in the axial direction, the second shielding member 30 overlaps at least a part of the gap G of the first shielding member 20. Such a coil unit 5 can suppress the transmission of magnetic lines through the gap G of the first shield member 20, thereby improving the performance of the coil unit 5. In addition, an increase in the axial dimension of the coil unit 5 caused by the second shield member 30 can be suppressed.

[0119] 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]

[0120] 1 Power transmission equipment 2 Power receiving device 5 Coil unit 10 Coil 10n Turn section 11 1st straight section 11F 1st straight line group 12 2nd straight section 12F 2nd straight line group 13 3rd straight section 13F 3rd straight section group 14 4th straight section 14F 4th straight line group 20 First shield member 20a Front side 20b Back side 20P 1st small piece 30 Second shield member 30P 2nd small piece 30PI 2nd inner piece 30PO 2nd outer piece 40 Third shield member 50 Thermal Conductive Layer 55 Insulating layer C center axis G gap S Wireless power transmission system

Claims

1. A coil formed in a spiral shape around a central axis; A first shield member having a front side surface facing the coil and a back side surface opposite to the front side surface; A second shield member disposed radially outward and / or inward of the coil so as to face the front surface of the first shield member; Equipped with the first shield member and the second shield member are magnetic, The first shield member is divided into a plurality of first small pieces, A gap is formed between adjacent first small pieces of the first shield member when viewed in the axial direction, A coil unit, wherein the second shield member overlaps at least a portion of the gap of the first shield member when viewed in the axial direction.

2. The coil unit according to claim 1 , wherein the second shield member is disposed radially outward of the coil and covers at least 80% or more of the gap present outside the coil when viewed in the axial direction.

3. The coil unit according to claim 1 , wherein the second shield member is disposed radially inward of the coil and covers at least 80% or more of the gap present inside the coil when viewed in the axial direction.

4. The coil unit according to claim 1 , wherein the first shielding member and the second shielding member comprise ferrite.

5. The coil unit according to claim 1 , wherein the first shield member and the second shield member have a relative magnetic permeability of 500 or more.

6. a third shield member disposed opposite the rear surface of the first shield member, The coil unit according to claim 1 , wherein the distance between the coil and the third shield member is 30 mm or less.

7. a third shield member disposed opposite the rear surface of the first shield member, The coil unit according to claim 1 , wherein the distance between the first shield member and the third shield member is 25 mm or less.

8. The coil includes a group of straight portions that are arranged in a radial direction and extend in one direction, The coil unit according to claim 1 , wherein at least a portion of the gap extends linearly and crosses at least a portion of the group of straight portions when viewed in the axial direction.

9. The coil unit according to claim 8 , wherein an angle formed between the straight portion and at least a part of the gap is equal to or greater than 80° and equal to or less than 100° when viewed in the axial direction.

10. The coil includes a group of curved portions including a plurality of curved portions arranged in a radial direction and extending along a circumferential direction, The coil unit according to claim 1 , wherein at least a portion of the gap extends linearly and crosses at least a portion of the group of curved portions when viewed in the axial direction.

11. The coil unit according to claim 10 , wherein an angle formed between a tangent to the curved portion and at least a part of the gap is equal to or greater than 80° and equal to or less than 100° when viewed in the axial direction.

12. A power transmitting device comprising the coil unit according to claim 1 .

13. A power receiving device comprising the coil unit according to claim 1 .

14. 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 unit according to claim 1 .

15. A moving body comprising the coil unit according to any one of claims 1 to 11.

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