Coil unit and method for manufacturing the same, as well as induction heating cooker, power transmission device, power receiving device and power transmission system

Abstract

To provide a coil unit that can stably and easily maintain the positional relationship between a sheet coil and another member such as another sheet coil.SOLUTION: A coil unit 10A according to an embodiment includes a first sheet coil 30 including a first coil conductor 31 having a spiral shape and a plurality of first protruding pieces 32 provided on the first coil conductor 31 so as to protrude from the outer circumferential surface 31B of the first coil conductor 31 facing outward in the radial direction perpendicular to the central axis C1 of the first coil conductor 31, and a base member 20 as a holding member having a base portion 21 and a plurality of spacer protrusions 22 protruding from the base portion 21. The first sheet coil 30 overlaps the base member 20 such that each of the plurality of spacer protrusions 22 contacts one of the plurality of first protruding pieces 32.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present disclosure relates to a coil unit, a method for manufacturing the same, and an induction cooker, a power transmission device, a power reception device, and a power transmission system.

Background Art

[0002] An induction cooker generates an induction magnetic field by passing a high-frequency current through a coil, and uses this induction magnetic field to heat a metal cooking utensil such as a pan.

[0003] Generally, a coil formed by winding Litz wire has been used as the coil incorporated in an induction cooker.

[0004] The coil of Litz wire has various advantages. For example, in Litz wire, the skin effect that can occur due to the application of a high-frequency current can be suppressed. Therefore, when the coil of Litz wire is used in an induction cooker, the cooking utensil can be efficiently heated by suppressing losses. However, since Litz wire is formed by twisting a plurality of enameled wires, the manufacturing cost is high and the manufacturing is laborious.

[0005] On the other hand, a so-called sheet coil can be manufactured more easily than the coil of Litz wire. The sheet coil has a spiral shape and a plate shape, and the cross-sectional shape of its conductor is rectangular. Therefore, the sheet coil can be easily mass-produced, for example, by punching with a mold. Therefore, the sheet coil is likely to suppress the manufacturing cost and the labor of manufacturing. In addition, the sheet coil is also advantageous in terms of thinning and weight reduction of the device to be incorporated such as an induction cooker.

[0006] Generally, it is difficult to increase the thickness of a sheet coil, but the inductance can be increased by multi-layerization. Various techniques related to multi-layerization of coils have been proposed so far. For example, Patent Document 1 discloses a structure in which a plurality of sheet coils are built in a block-shaped ceramic in a multi-layer manner. Patent Document 2 discloses a structure in which a plurality of coils of Litz wire are arranged in a multi-layer manner and adjacent coils are in contact with each other. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2016-085818 [Patent Document 2] Japanese Patent Publication No. 2015-162319 [Overview of the project] [Problems that the invention aims to solve]

[0008] In the structure of Patent Document 1, adjacent sheet coils are held in a separated state. It is desirable that such sheet coils be held stably and as simply as possible.

[0009] This disclosure has been made in consideration of the above circumstances, and the problem to be addressed is to provide a coil unit and a method for manufacturing the same that can stably and easily maintain the positional relationship between a sheet coil and other members, such as other sheet coils, as well as an induction heating cooker, a power transmission device, a power receiving device, and a power transmission system. [Means for solving the problem]

[0010] A coil unit according to one embodiment comprises a spiral-shaped first coil conductor, a first sheet coil having a plurality of first protruding pieces provided on the first coil conductor so as to protrude from at least one of the inner circumferential surface of the first coil conductor facing inward in a radial direction perpendicular to the central axis of the first coil conductor and the outer circumferential surface of the first coil conductor facing outward in the radial direction, and a holding material for holding the first sheet coil, wherein the first protruding pieces are in contact with the holding material.

[0011] The first protruding piece may be provided only on the outer circumferential surface of the first coil conductor.

[0012] The first coil conductor includes a plurality of turned portions arranged in the radial direction perpendicular to the central axis of the first coil conductor, and the first protruding pieces provided on each of the radially adjacent turned portions may be offset from each other in the circumferential direction about the central axis of the first coil conductor.

[0013] The first coil conductor includes a plurality of turned portions arranged radially perpendicular to the central axis of the first coil conductor, and the plurality of first protruding pieces include a group of one-side protruding pieces, which include a first offset protruding piece located away from one side in the circumferential direction centered on the central axis from a first reference line extending radially outward from the central axis so as to intersect the plurality of turned portions, and a second offset protruding piece located away from the first reference line on the other side in the circumferential direction, wherein the first offset protruding piece may be provided on one of the radially adjacent turned portions, and the second offset protruding piece may be provided on the other of the radially adjacent turned portions.

[0014] The first offset projection may be located on a first auxiliary line extending radially outward from the central axis, and the second offset projection may be located on a first auxiliary line that is symmetrical to the first auxiliary line with respect to the first reference line.

[0015] The turn portion is symmetrical with respect to a line symmetry reference line perpendicular to the central axis and the first reference line, and includes a circumferential portion that orbits the central axis. The plurality of first protruding pieces include a group of other-side protruding pieces, which include a third offset protruding piece located away from one side in the circumferential direction from a second reference line extending radially outward from the central axis in the opposite direction to the first reference line, and a fourth offset protruding piece located away from the other side in the circumferential direction from the second reference line. The third offset protruding piece may be provided on one of the radially adjacent turn portions, and the fourth offset protruding piece may be provided on the other of the radially adjacent turn portions.

[0016] The group of protruding pieces on one side and the group of protruding pieces on the other side may be point-symmetric with respect to the central axis of the first coil conductor when viewed in the axial direction of the first coil conductor.

[0017] The plurality of first protruding pieces include a third group of protruding pieces, which includes a fifth offset protruding piece positioned away from the line of symmetry reference line to one side in the circumferential direction, and a sixth offset protruding piece positioned away from the line of symmetry reference line to the other side in the circumferential direction, wherein the fifth offset protruding piece may be provided on one of the radially adjacent turn portions, and the sixth offset protruding piece may be provided on the other of the radially adjacent turn portions.

[0018] The second sheet coil further comprises a spiral-shaped second coil conductor provided so as to overlap with the retaining material and the first coil conductor, and the second coil conductor may include a plurality of turns arranged radially perpendicular to the central axis of the second coil conductor.

[0019] When the second sheet coil is inverted around a pivot axis perpendicular to the central axis of the second coil conductor, the shape of the second sheet coil may coincide with the shape of the first sheet coil.

[0020] The first coil conductor includes a plurality of turned portions arranged in the radial direction perpendicular to the central axis of the first coil conductor, the turned portions of the first coil conductor include a circumferential portion that is an annular in shape with a portion cut out around the central axis of the first coil conductor, the turned portions of the second coil conductor include a circumferential portion that is an annular in shape with a portion cut out around the central axis of the second coil conductor, the circumferential portions of the turned portions of the second coil conductor each overlap with any of the circumferential portions of the turned portions of the first coil conductor, and the first protruding piece may be provided on the circumferential portion of the turned portion of the first coil conductor.

[0021] The holding member is a base member having a base portion and a plurality of spacer protrusions protruding from the base portion, and the first sheet coil may overlap the base member such that the plurality of spacer protrusions contact any one of the plurality of first protruding pieces.

[0022] The spacer protrusion may pass between adjacent turn portions of the second coil conductor.

[0023] The coil unit according to an embodiment may further include a filling layer that fills a space between the first sheet coil and the base portion.

[0024] The holding member may be a carrier member that embeds the first sheet coil.

[0025] The coil unit according to an embodiment may further include a second sheet coil having a spiral-shaped second coil conductor embedded in the carrier member in a state of overlapping the first coil conductor.

[0026] The carrier member may be formed with a hole that exposes the first protruding piece to the outside through between adjacent turn portions of the second coil conductor.

[0027] The first protruding piece may contact the carrier member in the circumferential direction centered on the central axis of the first coil conductor.

[0028] A method for manufacturing a coil unit according to one embodiment comprises the steps of: preparing a base member having a base portion and a plurality of spacer protrusions protruding from the base portion; preparing a first sheet coil having a spiral-shaped first coil conductor and a plurality of first protruding pieces provided on the first coil conductor so as to protrude from at least one of the inner circumferential surface of the first coil conductor facing inward in a radial direction perpendicular to the central axis of the first coil conductor and the outer circumferential surface of the first coil conductor facing outward in the radial direction; and stacking the first sheet coil on the base member such that each of the plurality of spacer protrusions contacts one of the plurality of first protruding pieces. A method for manufacturing a coil unit according to one embodiment may further include a step of providing a molding material so as to fill the space between the base portion and the first sheet coil and embed the first sheet coil, and curing the molding material. A method for manufacturing a coil unit according to one embodiment may further include a step of removing the base member after the molding material has hardened.

[0029] Furthermore, a method for manufacturing a coil unit according to one embodiment includes the steps of: preparing a base member having a base portion and a plurality of spacer protrusions protruding from the base portion; preparing a first sheet coil having a spiral-shaped first coil conductor and a plurality of first protruding pieces provided on the first coil conductor so as to protrude from at least one of the inner circumferential surface of the first coil conductor facing inward in a radial direction perpendicular to the central axis of the first coil conductor and the outer circumferential surface of the first coil conductor facing outward in the radial direction; preparing a second sheet coil having a spiral-shaped second coil conductor; stacking the second sheet coil on the base member such that the second coil conductor is in contact with the base portion and the spacer protrusions do not interfere with the second coil conductor; and stacking the first sheet coil on the base member such that each of the plurality of spacer protrusions is in contact with one of the plurality of first protruding pieces. A method for manufacturing a coil unit according to one embodiment may further include a step of providing a molding material so as to fill the space between the base portion and the second coil conductor and the first coil conductor while embedding the first sheet coil and the second sheet coil, and then curing the molding material. A method for manufacturing a coil unit according to one embodiment may further include a step of removing the base member after the molding material has hardened.

[0030] Furthermore, an induction heating cooker according to one embodiment includes the coil unit described above. Furthermore, the power transmission device according to one embodiment includes the coil unit described above. Furthermore, the power receiving device according to one embodiment includes the coil unit described above. Furthermore, a power transmission system according to one embodiment comprises a power transmission device and a power receiving device, wherein at least one of the power transmission device and the power receiving device comprises the coil unit. [Effects of the Invention]

[0031] According to this disclosure, the positional relationship between a sheet coil and other members, such as other sheet coils, can be maintained stably and easily. [Brief explanation of the drawing]

[0032] [Figure 1] This is a diagram showing a coil unit according to the first embodiment. [Figure 2] This figure shows the base member constituting the coil unit according to the first embodiment. [Figure 3] This figure shows the first sheet coil constituting the coil unit according to the first embodiment. [Figure 4] This figure shows the second sheet coil constituting the coil unit according to the first embodiment. [Figure 5] This is a perspective view of a part of the coil unit according to the first embodiment. [Figure 6] This is a cross-sectional view of the coil unit along the line VI-VI in Figure 1. [Figure 7] This figure shows a coil intermediate for forming the first sheet coil shown in Figure 3 and the second sheet coil shown in Figure 4. [Figure 8] This is a diagram illustrating a method for manufacturing a coil unit according to the first embodiment. [Figure 9] This is a diagram illustrating a method for manufacturing a coil unit according to the first embodiment. [Figure 10] This figure shows a modified example of the first sheet coil shown in Figure 3. [Figure 11] This figure shows a coil unit according to a second embodiment. [Figure 12] This figure shows a coil unit according to the third embodiment. [Figure 13] This figure shows a coil unit according to the fourth embodiment. [Figure 14] This is a diagram showing a coil unit according to the fifth embodiment. [Figure 15] This is a cross-sectional view of the coil unit along the line XV-XV in Figure 14. [Figure 16] This figure illustrates a method for manufacturing a coil unit according to the fifth embodiment. [Figure 17] This figure illustrates a method for manufacturing a coil unit according to the fifth embodiment. [Figure 18] This figure illustrates a method for manufacturing a coil unit according to the fifth embodiment. [Figure 19] This figure shows an induction heating cooker equipped with a coil unit according to an embodiment. [Figure 20] This figure shows a wireless power transmission system equipped with a coil unit according to an embodiment. [Modes for carrying out the invention]

[0033] The embodiments will be described below with reference to the drawings.

[0034] In this specification, terms such as "sheet," "film," and "plate" are not distinguished from each other solely based on differences in name. Therefore, for example, "sheet" is a concept that includes components that could also be called films or plates.

[0035] Furthermore, in this specification, "sheet surface (board surface, film surface)" refers to the surface that coincides with the planar direction (surface direction) of the sheet-like member in question when viewed as a whole and in a broad sense.

[0036] <First Embodiment> Figure 1 shows a coil unit 10A according to the first embodiment. Figure 2 shows a base member 20 that constitutes the coil unit 10A. Figure 3 shows a first sheet coil 30 that constitutes the coil unit 10A. Figure 4 shows a second sheet coil 40 that constitutes the coil unit 10A. The coil unit 10A will be described below with reference to each figure.

[0037] (Coil unit) The coil unit 10A comprises a base member 20, a first sheet coil 30, and a second sheet coil 40. The first sheet coil 30 and the second sheet coil 40 are held in a state where they overlap the base member 20. That is, the coil unit 10A comprises the first sheet coil 30 and the second sheet coil 40 arranged in a multilayered state. In Figures 1 and 3, the first sheet coil 30 is marked with a dot for ease of explanation. The base member 20 is a member corresponding to the retaining member. The retaining member is a member that holds the first sheet coil 30 and the second sheet coil 40 in a state where they overlap at least in their axial direction. The retaining member is also a member that contacts the first sheet coil 30 and the second sheet coil 40 in part.

[0038] In this embodiment, the first sheet coil 30 and the second sheet coil 40 are connected in series. The coil unit 10A may be used, for example, as an induction heating coil in an induction cooker, or as a power transmission coil and power reception coil in contactless charging. In this case, the number of coil turns can be increased by connecting the first sheet coil 30 and the second sheet coil 40 in series. This increases the inductance when a high-frequency current is supplied to the first sheet coil 30 and the second sheet coil 40. However, the first sheet coil 30 and the second sheet coil 40 may be connected in parallel.

[0039] Figure 5 is a perspective view of a part of the coil unit 10A, and Figure 6 is a cross-sectional view of the coil unit 10A along the line VI-VI in Figure 1. Referring to Figures 2, 5, and 6, the base member 20 has a base portion 21 and a plurality of spacer protrusions 22 protruding from the base portion 21.

[0040] The base portion 21 has a flat main surface 21A that overlaps with the second sheet coil 40 in contact with it. More specifically, the second sheet coil 40 partially contacts the main surface 21A of the base portion 21. The spacer projection 22 is provided on the portion of the main surface 21A of the base portion 21 where the second sheet coil 40 does not overlap.

[0041] The spacer projection 22 protrudes beyond the second sheet coil 40 and contacts the first sheet coil 30 at its tip. The spacer projection 22 holds the first sheet coil 30 away from the base portion 21 and the second sheet coil 40. Specifically, multiple spacer projections 22 are provided in a dispersed manner, and the heights of the multiple spacer projections 22 are the same. As a result, the spacer projection 22 holds the first sheet coil 30 so that it is parallel to the second sheet coil 40 and the main surface 21A with a gap between them. A gap is formed between the first sheet coil 30 and the second sheet coil 40.

[0042] The base portion 21 is sheet-shaped, and the main surface 21A on which the spacer projection 22 is provided, as shown in Figure 2, is circular. However, the shape of the base portion 21 is not particularly limited as long as it is large enough to encompass the first sheet coil 30 and the second sheet coil 40 when they are stacked together. The base portion 21 does not have to be sheet-shaped; for example, it may be block-shaped. Also, the main surface 21A of the base portion 21 may be rectangular or other shapes.

[0043] The spacer projection 22 is columnar, and its tip is a flat surface. As shown in Figure 2, the cross-sectional shape of the spacer projection 22 is generally trapezoidal, but is not particularly limited. As will be described later, each of the multiple spacer projections 22 contacts one of the multiple first protruding pieces 32 provided on the spiral-shaped first coil conductor 31 in the first sheet coil 30, and holds the first sheet coil 30 away from the base portion 21 and the second sheet coil 40. A detailed explanation of the arrangement of the spacer projections 22 and the first protruding pieces 32 in the first sheet coil 30 will be given later.

[0044] In this embodiment, the base member 20 is made of resin, and the base portion 21 and the spacer projection 22 are formed simultaneously by integral molding. In this case, the base member 20 can be formed, for example, by injection molding or hot pressing. However, the material of the base member 20 is not particularly limited. The base member 20 may also be made of metal, for example.

[0045] As described above, the coil unit 10A may be used as an induction heating coil, or as a power transmission coil and power reception coil in contactless charging. In this case, when the coil unit 10A is used as an induction heating coil, power transmission coil, power reception coil, etc., with the base member 20 still attached, the base member 20 is formed of an insulating material such as resin. On the other hand, when the coil unit 10A is used as an induction heating coil, power transmission coil, power reception coil, etc., after the base member 20 has been removed, the base member 20 may be formed of a conductive material such as metal. Note that insulating properties refer to a volume resistivity of 10 10This means that the conductivity is greater than or equal to Ω·m. Conductivity means that the volume resistivity is 10 4 This means it is less than Ω·m.

[0046] The resin used to form the base member 20 may be a thermosetting resin or a thermoplastic resin. The thermosetting resin may be, for example, an epoxy resin. The thermoplastic resin may be, for example, a polyimide.

[0047] Furthermore, the base portion 21 of the base member 20 may be provided with positioning portions for positioning the first sheet coil 30 and the second sheet coil 40. Such positioning portions may be projections that protrude from the base portion 21 and pass through the second sheet coil 40 and the first sheet coil 30 in that order. The more such projections there are, the more stably the positions of the second sheet coil 40 and the first sheet coil 30 can be maintained. However, such projections require through holes to be formed in the first sheet coil 30 and the second sheet coil 40. Therefore, from the viewpoint of suppressing changes in coil performance, it may be desirable to limit the number and cross-sectional area of ​​the above-mentioned positioning projections.

[0048] As shown in Figure 3, the first sheet coil 30 has a spiral-shaped first coil conductor 31 and a plurality of first protruding pieces 32 provided on the first coil conductor 31. The first sheet coil 30 is formed entirely from a conductive material. In this embodiment, the first sheet coil 30 is formed from copper, but the first sheet coil 30 only needs to be conductive and may be formed from aluminum or the like.

[0049] The first sheet coil 30 is plate-shaped. In other words, the first sheet coil 30 is a coil also called a planar coil. More specifically, the first sheet coil 30 is a planar coil made of non-Litz wire. Figure 6 shows the wire cross-sectional shape in a direction perpendicular to the direction in which the first coil conductor 31, which forms a spiral shape in the first sheet coil 30, circulates. The conductive cross-sectional shape of the first coil conductor 31 is rectangular.

[0050] The symbol C1 shown in Figure 3 indicates the central axis of the first coil conductor 31, passing through the center of the spiral shape of the first coil conductor 31. Hereinafter, when referring to the axial direction of the first sheet coil 30 or the first coil conductor 31, that direction means the direction extending along the central axis C1 or the direction parallel to the central axis C1. The direction perpendicular to the central axis C1 is referred to as the radial direction of the first sheet coil 30 or the first coil conductor 31. The direction revolving around the central axis C1 is referred to as the circumferential direction of the first sheet coil 30 or the first coil conductor 31.

[0051] The first coil conductor 31 includes a plurality of turned portions 31n. The plurality of turned portions 31n are arranged radially outward from the central axis C1 of the spiral shape. The plurality of turned portions 31n are arranged radially so as to move radially outward from the central axis C1 and are connected in sequence, thereby forming a spiral shape. In other words, a spiral shape means the shape of a planar curve wound in a spiral. More specifically, a spiral shape is a shape that circles around a certain center, with the radial positions moving away from the center in sequence. In the illustrated embodiment, the spiral shape is located on a virtual plane perpendicular to the central axis.

[0052] The turned portion 31n has a shape in which the linear conductor portion does not form a complete ring (in other words, it forms a ring with a portion cut out) and rotates 360 degrees around the central axis C1. In the case of a so-called planar coil, both ends of the turned portion 31n are offset in the radial direction. In multiple turned portions 31n, the radially inward end of one turned portion 31n is connected to the radially outward end of another turned portion 31n, and the other turned portions 31n extend away from the central axis C1.

[0053] In turn section 31n, "n" represents a variable that takes a number from 1 to the number of turns of the first sheet coil 30. Hereafter, the turn section 31n closest to the central axis C1 may be referred to as turn section 311. Additionally, the turn section connected to the radially outer end of turn section 311 may be referred to as turn section 312, and the turn section connected to the radially outer end of turn section 312 may be referred to as turn section 313. In the example in Figure 3, the number of turns is 9, and the multiple turn sections 31n are composed of 9 turn sections 311 to 319. Turn section 319 corresponds to the turn section located on the outermost periphery.

[0054] To elaborate on the shape of the turn portion 31n, each turn portion 31n consists of one circumferential portion 31cn and one enlarged diameter portion 31en connected to the circumferential portion 31cn, or consists of one circumferential portion 31cn. In this embodiment, turn portions 311 to 318 consist of one circumferential portion 31cn and one enlarged diameter portion 31en. On the other hand, only the outermost turn portion 319 consists of one circumferential portion 31cn. The "n" in the circumferential portion 31cn and the enlarged diameter portion 31en also represents a variable that takes a number from 1 to a number corresponding to the number of turns of the first sheet coil 30. The circumferential portion 31cn of the innermost turn portion 311 is sometimes referred to as 31c1, and the enlarged diameter portion 31en is sometimes referred to as 32e1.

[0055] The circumferential portion 31cn is an annular shape with a portion cut out, extending in a circular manner around the central axis C. The circumferential portion 31cn has a starting end and an ending end, and the enlarged diameter portion 31en is connected to the ending end of the circumferential portion 31cn. The enlarged diameter portion 31en includes a portion that extends radially outward from the ending end of the circumferential portion 31cn while also extending in the circumferential direction. The enlarged diameter portion 31en is connected to the starting end of the circumferential portion 31cn in other turn portions 31n that are adjacent to the turn portion 31n to which it belongs in the radially outward direction. In other words, the enlarged diameter portion 31en connects the circumferential portions 31cn in radially adjacent turn portions 31n. As a result, the first coil conductor 31 as a whole forms a spiral shape.

[0056] In Figure 3, the symbol SL indicates a line of symmetry reference line perpendicular to the central axis C1. More specifically, in this embodiment, each circumferential portion 31cn is symmetric with respect to the line of symmetry reference line SL. More specifically, each circumferential portion 31cn is symmetric with respect to the line of symmetry reference line SL and orbits such that a circle of a predetermined radius is inscribed within it. The radii of the circles inscribed within each circumferential portion 31cn are different from each other. Furthermore, each circumferential portion 31cn is arranged such that the centers of the circles inscribed within each circumferential portion 31cn coincide, and the centers of the circles inscribed within each circumferential portion 31cn coincide with the central axis C1. That is, the multiple circumferential portions 31cn are arranged concentrically with respect to the central axis C1.

[0057] The radii of the circles inscribed in the multiple circumferential sections 31c1 to 31c9 increase in this order. In other words, the radius of the circle inscribed in the radially outer circumferential section 31cn of adjacent circumferential sections 31cn is larger than the radius of the circle inscribed in the radially inner circumferential section 31cn.

[0058] In this embodiment, as described above, the circumferential portion 31cn is symmetrical with respect to the line symmetry reference line SL and circulates such that a circle of a predetermined radius is inscribed within it. However, the circumferential portion 31cn does not necessarily have to follow a circle as long as it is symmetrical with respect to the line symmetry reference line SL. For example, the circumferential portion 31cn may be a rectangular ring with a portion cut out, as long as it is symmetrical with respect to the line symmetry reference line SL. Furthermore, the circumferential portion 31cn does not have to be symmetrical with respect to the line symmetry reference line SL.

[0059] Furthermore, the outermost turn portion 319 consists only of a circumferential portion 31c9, and a first lead portion 33 is connected to the end of the circumferential portion 31c9. The first lead portion 33 is used, for example, as a contact point with a high-frequency power supply.

[0060] The first coil conductor 31 has an inner circumferential surface 31A facing radially inward and an outer circumferential surface 31B facing radially outward. The inner circumferential surface 31A is the surface facing the central axis C1. The outer circumferential surface 31B is the surface facing the opposite side of the central axis C1. The inner circumferential surface 31A is formed by the surfaces of the multiple turn portions 31n facing the central axis C1 and extends in a spiral shape. The outer circumferential surface 31B is formed by the surfaces of the multiple turn portions 31n facing the opposite side of the central axis C1 and extends in a spiral shape. In this embodiment, the first protruding piece 32 described above is provided only on the outer circumferential surface 31B of the inner circumferential surface 31A and outer circumferential surface 31B. More specifically, the first protruding piece 32 is provided only on the circumferential portion 31cn and only on the outer circumferential surface of the circumferential portion 31cn.

[0061] The first protruding piece 32 may be provided on both the inner circumferential surface 31A and the outer circumferential surface 31B, or it may be provided only on the inner circumferential surface 31A. However, providing the first protruding piece 32 only on the outer circumferential surface 31B is preferable from the viewpoint of suppressing the influence of the first protruding piece 32 on the coil characteristics. This will be explained later.

[0062] As described above, each of the multiple spacer protrusions 22 contacts one of the multiple first protruding pieces 32 provided on the first coil conductor 31. That is, the first sheet coil 30 is placed on the base member 20 such that each of the multiple spacer protrusions 22 contacts one of the multiple first protruding pieces 32. As a result, the first sheet coil 30 is held away from the base member 21 and the second sheet coil 40 by the multiple spacer protrusions 22.

[0063] Referring to Figures 2 and 3 in comparison, the multiple first protruding pieces 32 are provided corresponding to the multiple spacer protrusions 22. In this embodiment, the formation pattern of the multiple first protruding pieces 32 matches the formation pattern of the multiple spacer protrusions 22. However, the formation pattern of the multiple first protruding pieces 32 does not necessarily have to match the formation pattern of the multiple spacer protrusions 22, as long as it is possible to hold the first sheet coil 30 away from the base portion 21 and the second sheet coil 40.

[0064] The formation patterns of the multiple first protruding pieces 32 will be described in detail below. In this embodiment, the multiple first protruding pieces 32 form a group of protruding pieces 32g1 on one side, a group of protruding pieces 32g2 on the other side, and a third group of protruding pieces 32g3.

[0065] The first reference line BL1 shown in Figure 3 is a hypothetical straight line extending radially outward from the central axis C1 so as to intersect with multiple turn sections 31n. The first reference line BL1 is perpendicular to both the central axis C1 and the line symmetry reference line SL. The group of protruding pieces 32g1 on one side is formed by multiple first protruding pieces 32 provided in the vicinity of the first reference line BL1.

[0066] The first protruding piece 32 forming the group of protruding pieces 32g1 on one side includes a first offset protruding piece 32-1 positioned away from the first reference line BL1 in the circumferential direction to one side, and a second offset protruding piece 32-2 positioned away from the first reference line BL1 in the circumferential direction to the other side.

[0067] In the one-sided projection piece group 32g1, a first offset projection piece 32-1 is provided on one of the radially adjacent turn portions 31n, and a second offset projection piece 32-2 is provided on the other of the radially adjacent turn portions 31n, and the first offset projection piece 32-1 and the second offset projection piece 32-2 are offset from each other in the circumferential direction. As a result, when viewing the turn portions 31n sequentially radially outward from the central axis C1 side along the first reference line BL1, the first offset projection piece 32-1 and the second offset projection piece 32-2 are positioned at different distances from each other with respect to the first reference line BL1. Multiple first offset projection pieces 32-1 and multiple second offset projection pieces 32-2 positioned in this alternating manner form the one-sided projection piece group 32g1. In other words, the group of protruding pieces 32g1 on one side has first offset protruding pieces 32-1 and second offset protruding pieces 32-2 alternately provided on the radially arranged turn portions 31n, and the first offset protruding pieces 32-1 and second offset protruding pieces 32-2 are positioned offset from each other in the circumferential direction from the first reference line BL1. The length from each first offset protruding piece 32-1 to the first reference line BL1 along the turn portion 32n on which the first offset protruding piece 32-1 is provided may be less than 1 / 2, less than 1 / 3, less than 1 / 4, or less than 1 / 5 of the total length of the turn portion 32n.

[0068] In this embodiment, as shown in Figure 3, a plurality of first offset protrusions 32-1 are arranged on a first one-sided auxiliary line SBL1 extending radially outward from the central axis C1, skipping one turn portion 31n, and a plurality of second offset protrusions 32-2 are also arranged on a first other-sided auxiliary line SBL2 extending radially outward from the central axis C1, skipping one turn portion 31n. The first other-sided auxiliary line SBL2 is symmetrical with the first one-sided auxiliary line SBL1 with respect to the first reference line BL1. However, the plurality of first offset protrusions 32-1 do not have to be arranged in a straight line, and the plurality of second offset protrusions 32-2 do not have to be arranged in a straight line. The first offset protrusions 32-1 and the second offset protrusions 32-2 are provided so as not to enter the formation range of the other other-sided protrusion group 32g2 and the formation range of the third protrusion group 32g3. In this embodiment, the first offset projection 32-1 and the second offset projection 32-2 are positioned less than 45 degrees away from the first reference line BL1 in the circumferential direction to one or the other side, specifically, about 20 degrees away from the first reference line BL1 in the circumferential direction. By positioning the first offset projection 32-1 and the second offset projection 32-2 relatively close to the first reference line BL1, they are prevented from interfering with the other group of projection pieces 32g2 and the third group of projection pieces 32g3.

[0069] On the other hand, the group of protruding pieces 32g2 on the other side is formed by a plurality of first protruding pieces 32 provided in the vicinity of the second reference line BL2. The second reference line BL2 shown in Figure 3 is a hypothetical straight line that extends radially outward from the central axis C1 so as to intersect with a plurality of turn portions 31n. The second reference line BL2 is perpendicular to both the central axis C1 and the line symmetry reference line SL. The second reference line BL2 extends from the central axis C1 in the opposite direction to the first reference line BL1.

[0070] The first protruding piece 32 forming the other-side protruding piece group 32g2 includes a third offset protruding piece 32-3 positioned away from the second reference line BL2 in the circumferential direction to one side, and a fourth offset protruding piece 32-4 positioned away from the second reference line BL2 in the circumferential direction to the other side.

[0071] In the other side group of protruding pieces 32g2, a third offset protruding piece 32-3 is provided on one of the radially adjacent turn portions 31n, and a fourth offset protruding piece 32-4 is provided on the other of the radially adjacent turn portions 31n, and the third offset protruding piece 32-3 and the fourth offset protruding piece 32-4 are offset from each other in the circumferential direction. As a result, when viewing the turn portions 31n sequentially radially outward from the central axis C1 side along the second reference line BL2, the third offset protruding piece 32-3 and the fourth offset protruding piece 32-4 are positioned alternately apart with respect to the second reference line BL2. Multiple third offset protruding pieces 32-3 and multiple fourth offset protruding pieces 32-4 positioned alternately in this manner form the other side group of protruding pieces 32g2. That is, the group of protruding pieces 32g2 on the other side has third offset protruding pieces 32-3 and fourth offset protruding pieces 32-4 alternately provided on the radially arranged turn portions 31n, and the third offset protruding pieces 32-3 and fourth offset protruding pieces 32-4 are positioned offset from each other in the circumferential direction from the second reference line BL2. The length from each third offset protruding piece 32-3 to the second reference line BL2 along the turn portion 31n on which the third offset protruding piece 32-3 is provided may be less than 1 / 2, less than 1 / 3, less than 1 / 4, or less than 1 / 5 of the total length of the turn portion 31n. The length along the turn portion 31n provided with each third offset projection 32-3 from each third offset projection 32-3 to the second reference line BL2 is shorter than the length along the turn portion 31n provided with each first offset projection 32-1 from each first offset projection 32-1 to the second reference line BL2, and shorter than the length along the turn portion 31n provided with each second offset projection 32-2 from each second offset projection 32-2 to the second reference line BL2.

[0072] In this embodiment, the group of protruding pieces 32g1 on one side and the group of protruding pieces 32g2 on the other side are point-symmetric with respect to the central axis C1 when viewed in the axial direction of the first coil conductor 31. This configuration not only improves the stability of the holding state of the first sheet coil 30 but also brings manufacturing advantages. Details of this will be described later.

[0073] Furthermore, the third group of protruding pieces 32g3 is formed by a plurality of first protruding pieces 32 provided in the vicinity of the line symmetry reference line SL. Specifically, when the line symmetry reference line SL is divided into a line segment extending to one side from the central axis C1 and a line segment extending to the other side, the plurality of enlarged diameter portions 31en described above are formed to be aligned along the line segment extending to one side of the line symmetry reference line SL. In contrast, a plurality of first protruding pieces 32 are provided in the vicinity of the line segment extending to the other side of the line symmetry reference line SL, and these plurality of first protruding pieces 32 form the third group of protruding pieces 32g3.

[0074] The first protruding piece 32 that forms the third group of protruding pieces 32g3 includes a fifth offset protruding piece 32-5 that is positioned away from the line of symmetry reference line SL on one side in the circumferential direction, and a sixth offset protruding piece 32-6 that is positioned away from the line of symmetry reference line SL on the other side in the circumferential direction.

[0075] In the third group of protruding pieces 32g3, a fifth offset protruding piece 32-5 is provided on one of two radially adjacent turn portions 31n, and a sixth offset protruding piece 32-6 is provided on the other of two radially adjacent turn portions 31n. Furthermore, the fifth offset protruding piece 32-5 and the sixth offset protruding piece 32-6 are offset from each other in the circumferential direction. As a result, when viewing the turn portions 31n sequentially radially outward from the central axis C1 side along the line of symmetry reference line SL, the fifth offset protruding piece 32-5 and the sixth offset protruding piece 32-6 are positioned alternately apart with respect to the line of symmetry reference line SL. These multiple fifth offset protruding pieces 32-5 and multiple sixth offset protruding pieces 32-6, positioned alternately in this manner, form the third group of protruding pieces 32g3.

[0076] More specifically, the multiple fifth offset protrusions 32-5 are aligned on a straight line extending radially, skipping one turn portion 31n, and the multiple sixth offset protrusions 32-6 are also aligned on a straight line extending radially, skipping one turn portion 31n. However, the multiple fifth offset protrusions 32-5 do not have to be aligned on a straight line, and the multiple sixth offset protrusions 32-6 do not have to be aligned on a straight line. In addition, as with the case of the one-sided protrusion group 32g1 described above, the fifth offset protrusions 32-5 and the sixth offset protrusions 32-6 are provided so as not to enter the formation range of the other one-sided protrusion group 32g1 and the other-sided protrusion group 32g2. In this embodiment, similar to the case of the one-sided projection group 32g1 described above, the fifth offset projection 32-5 and the sixth offset projection 32-6 are separated from the line symmetry reference line SL by a range of less than 45 degrees in the circumferential direction to one or the other side, specifically by about 20 degrees in the circumferential direction from the line symmetry reference line SL. In this way, the fifth offset projection 32-5 and the sixth offset projection 32-6 are provided relatively close to the line symmetry reference line SL so as not to interfere with the other one-sided projection group 32g1 and the other-sided projection group 32g2.

[0077] Next, as shown in Figure 4, the second sheet coil 40 has a spiral-shaped second coil conductor 41 and a plurality of second protruding pieces 42 provided on the second coil conductor 41. The second sheet coil 40 is formed entirely from a conductive material. In this embodiment, the second sheet coil 40 is formed from copper, but the second sheet coil 40 only needs to be conductive and may be formed from aluminum or the like.

[0078] The second sheet coil 40 is a planar coil made of non-Litz wire, similar to the first sheet coil 30. Figure 6 shows the wire cross-sectional shape in the direction perpendicular to the direction in which the second coil conductor 41, which forms a spiral shape in the second sheet coil 40, rotates. The conductive cross-sectional shape of the second coil conductor 41 is rectangular.

[0079] The symbol C2 shown in Figure 4 indicates the central axis of the second coil conductor 41, passing through the center of the spiral shape of the second coil conductor 41. Hereinafter, when referring to the axial direction of the second sheet coil 40 or the second coil conductor 41, that direction means the direction extending along the central axis C2 or the direction parallel to the central axis C2. The direction perpendicular to the central axis C2 is called the radial direction of the second coil conductor 41. The direction that revolves around the central axis C2 is called the circumferential direction of the second coil conductor 41.

[0080] When the second coil conductor 41 is incorporated into the coil unit 10A so as to be located between the base portion 21 and the first coil conductor 31, in this example it is coaxial with the first coil conductor 31. Therefore, as shown in Figure 1, when the first sheet coil 30 and the second sheet coil 40 are incorporated into the coil unit 10A, the central axis C1 of the first coil conductor 31 and the central axis C2 of the second coil conductor 41 coincide. Thus, in the coil unit 10A, the axial, radial, and circumferential directions of the first sheet coil 30 coincide with the axial, radial, and circumferential directions of the second sheet coil 40, respectively. Note that the first coil conductor 31 and the second coil conductor 41 do not necessarily have to be coaxial.

[0081] In this embodiment, when the second sheet coil 40 is inverted around a pivot axis perpendicular to the central axis C2 of the second coil conductor 41, the shape of the second sheet coil 40 matches the shape of the first sheet coil 30. More specifically, the second sheet coil 40 in this embodiment is constructed by inverting a first sheet coil 30 that is different from the first sheet coil 30 incorporated into the coil unit 10A. As a result, when the second sheet coil 40 is inverted around a pivot axis perpendicular to the central axis C2 of the second coil conductor 41, the shape of the second sheet coil 40 matches the shape of the first sheet coil 30. More specifically, when the second sheet coil 40 is inverted around a pivot axis corresponding to the line symmetry reference line SL shown in Figure 1, the shape of the second sheet coil 40 matches the shape of the first sheet coil 30.

[0082] As described above, when the second sheet coil 40 is inverted around a pivot axis perpendicular to the central axis C2 of the second coil conductor 41, if the shape of the second sheet coil 40 matches the shape of the first sheet coil 30, then, as shown in Figure 1, the first sheet coil 30 and the second sheet coil 40 can be superimposed such that they are coaxially arranged and are symmetrical with respect to a straight line perpendicular to the central axes C1 and C2. In Figure 1, the first sheet coil 30 and the second sheet coil 40 are symmetrical with respect to the symmetry reference line SL defined for the first sheet coil 30.

[0083] The second coil conductor 41 has the shape of the first coil conductor 31 inverted, and therefore includes a plurality of turns 41n arranged radially. As shown in Figures 5 and 6, the spacer projection 22 passes between adjacent turns 41n in the second coil conductor 41. In the turns 41n, "n" represents a variable that takes a number from 1 to the number of turns of the second sheet coil 40. The second coil conductor 41 has 9 turns, similar to the first coil conductor 31, and the plurality of turns 41n consist of 9 turns 411 to 419. Turn 419 corresponds to the turn located on the outermost periphery.

[0084] Each turn section 41n, like the turn section 31n, consists of one circumferential section 41cn and one enlarged diameter section 41en connected to the circumferential section 41cn, or consists of one circumferential section 41cn. In this embodiment, turn sections 411 to 418 consist of one circumferential section 41cn and one enlarged diameter section 41en. On the other hand, only the outermost turn section 419 consists of one circumferential section 41cn. The "n" in the circumferential section 41cn and the enlarged diameter section 41en also represents a variable that takes a number from 1 to the number of turns of the second sheet coil 40. The circumferential section 41cn of turn section 411 is sometimes referred to as 41c1, and the enlarged diameter section 41en is sometimes referred to as 42e1.

[0085] Referring together to Figures 1 and 4, the circumferential portions 41cn of the turn portion 41n of the second coil conductor 41 each overlap with the corresponding circumferential portions 31cn of the turn portion 31n of the first coil conductor 31 without protruding. More specifically, each circumferential portion 41cn overlaps with the corresponding circumferential portion 31cn, with their contours aligned. Specifically, for example, circumferential portion 41c1 overlaps with the corresponding circumferential portion 31c1, and circumferential portion 41c2 overlaps with the corresponding circumferential portion 31c2. A similar relationship holds between circumferential portions 41c3 to c9 and the corresponding circumferential portions 31c3 to c9. On the other hand, the second protruding piece 42 protrudes from the turn portion 31n of the first coil conductor 31.

[0086] Furthermore, the circumferential portion 41cn may overlap the circumferential portion 31cn in a way that it protrudes from the corresponding circumferential portion 31cn. Alternatively, the circumferential portion 41cn may be thinner than the corresponding circumferential portion 31cn and overlap the corresponding circumferential portion 31cn in a way that it is recessed relative to the corresponding circumferential portion 31cn. However, if the circumferential portion 41cn protrudes from the corresponding circumferential portion 31cn, it may lead to an increase in the size of the first protruding piece 32. Also, if the circumferential portion 41cn is recessed relative to the corresponding circumferential portion 31cn, the volume of the second coil conductor 41 may decrease.

[0087] Furthermore, as described above, the first sheet coil 30 and the second sheet coil 40 are connected in series. When the first sheet coil 30 and the second sheet coil 40 are connected in series, for example, the starting end P1 (see Figure 3) of the circumferential portion 31c1 of the innermost turn portion 311 of the first coil conductor 31 and the starting end P2 (see Figure 4) of the circumferential portion 41c1 of the innermost turn portion 411 of the second coil conductor 41 may be connected via a conductor (not shown). In this case, the conductor is provided in the gap between the first sheet coil 30 and the second sheet coil 40. The connection between the conductor and each starting end P1, P2 may be made by ultrasonic welding or by conductive adhesive.

[0088] The second protruding piece 42 in the second sheet coil 40 may be omitted.

[0089] (Manufacturing method for coil units) Next, an example of a manufacturing method for the coil unit 10A will be described with reference to Figures 7 to 9.

[0090] Figure 7 shows a coil intermediate 60 for forming the first sheet coil 30 and the second sheet coil 40. The coil intermediate 60 shown in Figure 7 has a first coil conductor 31 and a plurality of connecting parts 61, also called tie bars, that connect adjacent turn portions 31n in the first coil conductor 31. Each pair of adjacent turn portions 31n has six connecting parts 61 that are offset in the circumferential direction. Any of the six connecting parts 61 between adjacent pairs of turn portions 31n are aligned radially with any of the six connecting parts 61 between other adjacent pairs of turn portions 31n. Thus, the coil intermediate 60 has six groups of multiple connecting parts 61 aligned radially. The coil intermediate 60 may be formed, for example, by punching out a copper plate with a die.

[0091] In this embodiment, some of the multiple connecting portions 61 are completely removed, and other parts of the multiple connecting portions 61 are partially removed to form the first protruding piece 32. Therefore, the multiple connecting portions 61 are provided in positions corresponding to where the first protruding piece 32 is intended to be formed.

[0092] In this embodiment, the removal of the connecting portion 61 is performed by punching with a die 200. At this time, as shown in Figure 8, multiple (two in the illustration) coil intermediates 60 are stacked so that their contours match. Then, the die 200 is pressed against the multiple coil intermediates 60. The die 200 includes a protrusion that removes the entire connecting portion 61 and a protrusion that partially removes the connecting portion 61 to form the first protruding piece 32.

[0093] Then, after pressing the mold 200, multiple (two in the illustration) first sheet coils 30 are formed, as shown in Figure 9. Here, for example, one of the two first sheet coils 30 is used as is. Also, one of the two first sheet coils 30 is flipped over to form a second sheet coil 40. In this way, the first sheet coil 30 and the second sheet coil 40 are prepared.

[0094] Next, the base member 20 is prepared. Then, the second sheet coil 40 is placed on the base member 20 such that the second coil conductor 41 is in contact with the base portion 21 of the base member 20 and the spacer projections 22 do not interfere with the second coil conductor 41. Subsequently, the first sheet coil 30 is placed on the base member 20 such that each of the multiple spacer projections 22 is in contact with one of the multiple first protruding pieces 32. The coil unit 10A according to this embodiment is manufactured by following these steps.

[0095] The coil unit 10A according to the embodiment described above comprises a spiral-shaped first coil conductor 31, a first sheet coil 30 having a plurality of first protruding pieces 32 provided on the first coil conductor 31 so as to protrude from at least one of the inner circumferential surface 31A of the first coil conductor 31 which faces inward in the radial direction perpendicular to the central axis C1 of the first coil conductor 31, and the outer circumferential surface 31B of the first coil conductor 31 which faces outward in the radial direction, and a base member 20 having a base portion 21 and a plurality of spacer protrusions 22 protruding from the base portion 21. The first sheet coil 30 is placed on the base member 20 such that each of the plurality of spacer protrusions 22 contacts one of the plurality of first protruding pieces 32.

[0096] In this coil unit 10A, the first sheet coil 30 can be held away from the base portion 21 by the contact between the first protruding piece 32 provided on the first coil conductor 31 of the first sheet coil 30 and the spacer projection 22 provided on the base portion 21 of the base member 20. In this case, since the first sheet coil 30 is held away from the base portion 21 by two types of members, the structure for holding the first sheet coil 30 away from the base portion 21 is not complicated and can be manufactured simply. In addition, the contact between the first protruding piece 32 and the spacer projection 22 also suppresses displacement of the first sheet coil 30 in the circumferential and radial directions relative to the base member 20. In particular, spiral-shaped coils may gradually shift and loosen in the circumferential direction over time, but the contact between the first protruding piece 32 and the base member 20 can suppress this displacement. Furthermore, since the first protruding piece 32 protrudes from the inner circumferential surface 31A and / or outer circumferential surface 31B (in this example, the outer circumferential surface 31B) of the first coil conductor 31, a space can be formed between the first coil conductor 31 and the base portion 21. Thus, the positional relationship between the first sheet coil 30 and the base portion 21 of the base member 20, which is another component, can be maintained stably and easily. Moreover, while forming a space between the first sheet coil 30 and the base portion 21, the first sheet coil 30 can be easily held away from the base portion 21.

[0097] In particular, the first protruding piece 32 is provided only on the outer circumferential surface 31B of the first coil conductor 31. When current flows through the first coil conductor 31, the current tends to concentrate on the inner circumferential surface 31A. Therefore, in a configuration where the first protruding piece 32 is provided on the outer circumferential surface 31B of the first coil conductor 31, it is possible to suppress the increase in losses caused by current flowing through the first protruding piece 32. Thus, changes in the performance of the first sheet coil 30 can be suppressed.

[0098] Figure 10 shows a modified first sheet coil 30' in which the first protruding piece 32 is provided only on the inner circumferential surface 31A of the first coil conductor 31. This embodiment can suppress losses more effectively than the modified example shown in Figure 10. Table 1 below shows simulation results comparing the inductance (μH), impedance (Ω), and Q value of the first sheet coil 30 in the first embodiment with the inductance (μH), impedance (Ω), and Q value of the modified first sheet coil 30' shown in Figure 10.

[0099] [Table 1]

[0100] The simulation results shown in Table 1 show that the inductance and Q value in the embodiment are higher than those in the comparative example, and the impedance in the embodiment is smaller than that of the modified example. These simulation results also confirm that the configuration in which the first protruding piece 32 is provided on the outer peripheral surface 31B of the first coil conductor 31 is beneficial.

[0101] Furthermore, in this embodiment, the first coil conductor 31 includes a plurality of turn portions 31n arranged radially perpendicular to the central axis C1 of the first coil conductor 31, and the first protruding pieces 32 provided on each of the radially adjacent turn portions 31n are offset from each other in the circumferential direction about the central axis C1 of the first coil conductor 31. In this configuration, the contact points between the first protruding pieces 32 and the spacer projections 22 are dispersed, so that the first sheet coil 30 can be stably held away from the base portion 21. Moreover, the circumferential displacement of the first sheet coil 30 over time can be effectively suppressed.

[0102] Furthermore, the multiple first protruding pieces 32 include a first offset protruding piece 32-1 positioned away from one side in the circumferential direction from a first reference line BL1 that extends radially outward from the central axis C1 of the first coil conductor 31 so as to intersect with the multiple turn portions 31n, and a second offset protruding piece 32-2 positioned away from the other side in the circumferential direction from the first reference line BL1. The first offset protruding piece 32-1 is provided on one of the radially adjacent turn portions 31n, and the second offset protruding piece 32-2 is provided on the other of the radially adjacent turn portions 31n, and the first offset protruding piece 32-1 and the second offset protruding piece 32-2 are offset from each other in the circumferential direction. Then, when viewing the turn portion 31n radially outward from the central axis C1 side along the first reference line BL1, the first offset projection 32-1 and the second offset projection 32-2 are positioned alternately apart from the first reference line BL1, forming a group of projection pieces 32g1 on one side.

[0103] In this configuration, rotation of the first sheet coil 30 around the first reference line BL1 is suppressed, thereby improving the stability of the holding state of the first sheet coil 30.

[0104] Furthermore, the turn portion 31n of the first coil conductor 31 is symmetric with respect to a line symmetric reference line SL perpendicular to the central axis C1 and the first reference line BL1, and includes a circumferential portion 31cn that orbits the central axis C1. The plurality of first protruding pieces 32 include a third offset protruding piece 32-3 positioned away from one side in the circumferential direction from the second reference line BL2, which extends radially outward from the central axis C1 in the opposite direction to the first reference line BL1, and a fourth offset protruding piece 32-4 positioned away from the other side in the circumferential direction from the second reference line BL2. The third offset protruding piece 32-3 is provided on one of two radially adjacent turn portions 31n, and the fourth offset protruding piece 32-4 is provided on the other of two radially adjacent turn portions 31n, and the third offset protruding piece 32-3 and the fourth offset protruding piece 32-4 are offset from each other in the circumferential direction. Then, when viewing the turn portion 31n radially outward from the central axis C1 side along the second reference line BL2, the third offset projection 32-3 and the fourth offset projection 32-4 are positioned alternately apart with respect to the second reference line BL2, forming the other side projection group 32g2. Here, the one side projection group 32g1 and the other side projection group 32g2 are point-symmetric with respect to the central axis C1 of the first coil conductor 31 when viewed in the axial direction of the first coil conductor 31.

[0105] In this configuration, rotation of the first sheet coil 30 around the line symmetry reference line SL is suppressed, thereby improving the stability of the holding state of the first sheet coil 30. Furthermore, the uniform arrangement of the first protruding pieces 32 more effectively suppresses circumferential displacement of the first sheet coil 30 over time. In particular, since the group of protruding pieces 32g1 on one side and the group of protruding pieces 32g2 on the other side are point-symmetric with respect to the central axis C1 of the first coil conductor 31, when the first sheet coil 30 is inverted to form the second sheet coil 40 and the first sheet coil 30 and the second sheet coil 40 are stacked, a structure can be easily formed in which the second protruding piece 42 of the second sheet coil 40 and the spacer projection 22 come into contact with the first protruding piece 32 without interference between them. As a result, as shown in Figures 8 and 9, it becomes possible to form a multilayer structure of the sheet coil while reducing manufacturing costs and effort.

[0106] Furthermore, the multiple first protruding pieces 32 include a fifth offset protruding piece 32-5 positioned away from the line of symmetry reference line SL in the circumferential direction, and a sixth offset protruding piece 32-6 positioned away from the line of symmetry reference line SL in the circumferential direction. The fifth offset protruding piece 32-5 is provided on one of the radially adjacent turn portions 31n, and the sixth offset protruding piece 32-6 is provided on the other of the radially adjacent turn portions 31n, and the fifth offset protruding piece 32-5 and the sixth offset protruding piece 32-6 are offset from each other in the circumferential direction. When the turn portions 31n are viewed sequentially radially outward from the central axis C1 side along the line of symmetry reference line SL, the fifth offset protruding piece 32-5 and the sixth offset protruding piece 32-6 are positioned alternately away from the line of symmetry reference line SL, forming a third group of protruding pieces 32g3.

[0107] This configuration also suppresses the rotation of the first sheet coil 30 around the line of symmetry reference line SL, thereby improving the stability of the holding state of the first sheet coil 30. Furthermore, the uniform arrangement of the first protruding pieces 32 can more effectively suppress the circumferential displacement of the first sheet coil 30 over time.

[0108] Furthermore, the coil unit 10A according to this embodiment further comprises a second sheet coil 40 having a spiral-shaped second coil conductor 41 located between the base portion 21 and the first coil conductor 31. The second coil conductor 41 includes a plurality of turn portions 41n arranged radially perpendicular to the central axis C2 of the second coil conductor 41, and the spacer projection 22 passes between adjacent turn portions 41n in the second coil conductor 41.

[0109] In this configuration, a space is formed between the first sheet coil 30 and the second sheet coil 40, while the first sheet coil 30 can be easily held away from the second sheet coil 40. Furthermore, the inductance can be increased by using multiple layers of sheet coils.

[0110] In this embodiment, when the second sheet coil 40 is inverted around a pivot axis perpendicular to the central axis C2 of the second coil conductor 41, the shape of the second sheet coil 40 matches the shape of the first sheet coil 30.

[0111] In this configuration, the first sheet coil 30 and the second sheet coil 40 can be made common, thus reducing the number of parts in the coil unit 10A and improving manufacturing efficiency. In particular, as mentioned above, when the group of protruding pieces 32g1 on one side and the group of protruding pieces 32g2 on the other side are point-symmetric with respect to the center of the spiral shape, a structure can be easily formed in which the spacer protrusion 22 and the first protruding piece 32 come into contact without interfering with the second protruding piece 42 and the spacer protrusion 22 in the second sheet coil 40. Specifically, the spacer protrusion 22 and the first protruding piece 32 can come into contact while avoiding a complex configuration of the spacer protrusion 22. Therefore, a multilayer structure of the sheet coil can be formed while reducing manufacturing costs and effort.

[0112] Furthermore, each of the circumferential portions 41cn in the turned portion 41n of the second coil conductor 41 overlaps with one of the circumferential portions 31cn in the turned portion 31n of the first coil conductor 31. The first protruding piece 32 is provided on the circumferential portion 31cn in the turned portion 31n of the first coil conductor 31. This configuration is advantageous in terms of material cost and suppressing changes in coil characteristics because it is possible to bring the spacer projection 22 and the first protruding piece 32 into contact while avoiding a complex structure for the spacer projection 22 and without increasing the size of the first protruding piece 32.

[0113] <Second Embodiment> Next, a coil unit 10B according to a second embodiment will be described. Figure 11 is a diagram showing the coil unit 10B according to the second embodiment, and is more specifically a schematic cross-sectional view. Components in this embodiment that are the same as those in the first embodiment are denoted by the same reference numerals, and redundant explanations are omitted.

[0114] In addition to the base member 20, the first sheet coil 30, and the second sheet coil 40, the coil unit 10B further includes a filling layer 50 that fills the space between the first sheet coil 30 and the base portion 21 of the base member 20.

[0115] The filling layer 50 may be formed of an insulating material such as resin. Alternatively, the filling layer 50 may include granules composed of an insulating material such as resin and a magnetic material contained in the insulating material. The granules composed of magnetic material may be one or more of the following: ferrite, particularly soft magnetic material; nanocrystalline magnetic material; silicon steel; electromagnetic soft iron; and amorphous metal. The insulating material such as resin may be glass fiber reinforced polyamide.

[0116] According to the coil unit 10B of the second embodiment, the filling layer 50 ensures that the first sheet coil 30 is kept separate from the second sheet coil 40 and the base portion 21 of the base member 20. Furthermore, if the filling layer 50 includes granular material made of magnetic material, the coil performance may be improved compared to when the filling layer 50 is made of insulating material only.

[0117] <Third Embodiment> Next, a coil unit 10C according to the third embodiment will be described. Figure 12 is a diagram showing the coil unit 10C according to the third embodiment, and is more specifically a schematic cross-sectional view. Components in this embodiment that are the same as those in the first and second embodiments are denoted by the same reference numerals, and redundant explanations are omitted.

[0118] The coil unit 10C further comprises a first sheet coil 30, a second sheet coil 40, and a filling layer 50 that fills the space between the first sheet coil 30 and the second sheet coil 40. The base member 20 is removed after the filling layer 50 has been filled and cured. In this configuration, the base member 20 may be made of metal.

[0119] <Fourth Embodiment> Next, a coil unit 10D according to the fourth embodiment will be described. Figure 13 is a diagram showing the coil unit 10D according to the fourth embodiment, and is more specifically a schematic cross-sectional view. Components in this embodiment that are the same as those in the first to third embodiments are denoted by the same reference numerals, and redundant explanations are omitted.

[0120] The coil unit 10D comprises a base member 20 and a first sheet coil 30. A space is formed between the first sheet coil 30 and the base portion 21 of the base member 20, and the first sheet coil 30 is supported by spacer protrusions 22. In the coil unit 10D, the space between the first sheet coil 30 and the base member 20 may be filled with the filling layer 50 shown in Figures 11 and 12. The coil unit 10D is manufactured by the steps of preparing the base member 20, preparing the first sheet coil 30, and stacking the first sheet coil 30 on the base member 20 such that each of the multiple spacer protrusions 22 contacts one of the multiple first protruding pieces 32.

[0121] <Fifth Embodiment> Next, a coil unit 10E according to the fifth embodiment will be described. Figure 14 is a diagram showing the coil unit 10E according to the fifth embodiment. Figure 15 is a cross-sectional view of the coil unit 10E along the line XV-XV in Figure 14. Components in this embodiment that are the same as those in the first to fourth embodiments are denoted by the same reference numerals, and redundant explanations are omitted.

[0122] The coil unit 10E comprises a carrier member 80, a first sheet coil 30, and a second sheet coil 40. The first sheet coil 30 and the second sheet coil 40 are held overlapping on the carrier member 80. More specifically, the first sheet coil 30 and the second sheet coil 40 are held on the carrier member 80 such that the first coil conductor 31 and the second coil conductor 41 overlap in the same manner as described in the first embodiment.

[0123] The carrier member 80 is a member corresponding to the holding material. As shown in Figure 15, the carrier member 80 holds the first sheet coil 30 and the second sheet coil 40 in an embedded state. Specifically, the carrier member 80 embeds the first sheet coil 30 such that it is covered from both sides in its axial direction. On the other hand, the carrier member 80 embeds the second sheet coil 40 such that one side of the second sheet coil 40 in its axial direction (the upper side in Figure 15) is exposed to the outside. The carrier member 80 also fills the spaces between adjacent turn portions 31n in the first coil conductor 31 and between adjacent turn portions 41n in the second coil conductor 41.

[0124] The first protruding piece 32 of the first sheet coil 30 contacts the carrier member 80 in the circumferential direction around the central axis C1 of the first coil conductor 31. The second protruding piece 42 of the second sheet coil 40 contacts the carrier member 80 in the circumferential direction around the central axis C2 of the second coil conductor 41. As a result, the positions of the first sheet coil 30 and the second sheet coil 40 are stably maintained by the carrier member 80.

[0125] Furthermore, the carrier member 80 has a hole 81 that allows the first protruding piece 32 to be exposed to the outside by passing between adjacent turned portions 41n in the second coil conductor 41. The hole 81 extends in the axial direction of the first sheet coil 30. The hole 81 can promote cooling of the first sheet coil 30 by, for example, receiving air. Also, if, for example, a member with high heat dissipation is provided in the hole 81, cooling of the first sheet coil 30 can be promoted.

[0126] The carrier member 80 may be formed of an insulating material such as resin. Alternatively, the carrier member 80 may include granules composed of an insulating material such as resin and a magnetic material contained in the insulating material. The granules composed of magnetic material may be one or more of the following: ferrite, especially soft magnetic material ferrite, nanocrystalline magnetic material, silicon steel, electromagnetic soft iron, and amorphous metal. The insulating material such as resin may be glass fiber reinforced polyamide.

[0127] An example of a method for manufacturing the coil unit 10E will be described below with reference to Figures 16 to 18. In this embodiment, the coil unit 10E according to the fifth embodiment is manufactured using the coil unit 10A according to the first embodiment.

[0128] First, as shown in Figure 16, a coil unit 10A according to the first embodiment is prepared. Next, as shown in Figure 17, a molding material RM is provided so as to fill the space between the base portion 21 of the base member 20 and the second coil conductor 41 and the first coil conductor 31, while embedding the first sheet coil 30 and the second sheet coil 40. Then, as the molding material RM hardens, a carrier member 80 is formed. The molding material RM is, for example, a paste-like or liquid material. The molding material RM may be an insulating material such as a resin, or it may include an insulating material such as a resin and granules composed of a magnetic material contained in the insulating material.

[0129] Then, after the molding material RM hardens and becomes the carrier member 80, the base member 20 is removed as shown in Figure 18. This creates the coil unit 10E. In the carrier member 80, holes 81 are formed where the spacer projections 22 were before the removal of the base member 20. If the molding material RM is applied to the coil unit 10E shown in Figure 13 using the same procedure as in Figures 16 to 18, a coil unit consisting of the carrier member 80 and the first sheet coil 30 can be created.

[0130] In the coil unit 10E according to the fifth embodiment described above, the first coil conductor 31 in the first sheet coil 30 and the second coil conductor 41 in the second sheet coil 40 are embedded in and held by the carrier member 80. The first protruding piece 32 in the first sheet coil 30 is in contact with the carrier member 80. The second protruding piece 42 in the second sheet coil 40 is in contact with the carrier member 80. As a result, the positions of the first sheet coil 30 and the second sheet coil 40 are stably held by the carrier member 80. In other words, the contact between the first protruding piece 32 and the second protruding piece 42 and the carrier member 80 prevents the first sheet coil 30 and the second sheet coil 40 from shifting in the circumferential and radial directions relative to the carrier member 80. In particular, spiral-shaped coils may gradually shift over time as they loosen in the circumferential direction, but this shift can be suppressed by the contact between the first protruding piece 32 and the second protruding piece 42 and the carrier member 80. Therefore, the positional relationship between the first sheet coil 30 and the second sheet coil 40 and the carrier member 80, which is another component, can be maintained stably and easily.

[0131] Furthermore, in this embodiment, similar to the first embodiment, the first coil conductor 31 includes a plurality of turn portions 31n arranged radially perpendicular to the central axis C1 of the first coil conductor 31, and the first protruding pieces 32 provided on each of the radially adjacent turn portions 31n are offset from each other in the circumferential direction about the central axis C1 of the first coil conductor 31. With this configuration, the circumferential displacement of the first sheet coil 30 over time can be effectively suppressed. Similarly, circumferential displacement of the second sheet coil 40 can also be effectively suppressed.

[0132] Furthermore, in this embodiment as well, similar to the first embodiment, the plurality of first protruding pieces 32 include a first offset protruding piece 32-1 positioned away from one side in the circumferential direction from a first reference line BL1 that extends radially outward from the central axis C1 of the first coil conductor 31 so as to intersect with a plurality of turn portions 31n, and a second offset protruding piece 32-2 positioned away from the other side in the circumferential direction from the first reference line BL1. The first offset protruding piece 32-1 is provided on one of the radially adjacent turn portions 31n, and the second offset protruding piece 32-2 is provided on the other of the radially adjacent turn portions 31n, and the first offset protruding piece 32-1 and the second offset protruding piece 32-2 are offset from each other in the circumferential direction. Then, when viewing the turn portion 31n radially outward from the central axis C1 side along the first reference line BL1, the first offset projection 32-1 and the second offset projection 32-2 are positioned alternately apart from the first reference line BL1, forming a group of projection pieces 32g1 on one side.

[0133] Furthermore, the turn portion 31n of the first coil conductor 31 is symmetric with respect to a line symmetric reference line SL perpendicular to the central axis C1 and the first reference line BL1, and includes a circumferential portion 31cn that orbits the central axis C1. The plurality of first protruding pieces 32 include a third offset protruding piece 32-3 positioned away from one side in the circumferential direction from the second reference line BL2, which extends radially outward from the central axis C1 in the opposite direction to the first reference line BL1, and a fourth offset protruding piece 32-4 positioned away from the other side in the circumferential direction from the second reference line BL2. The third offset protruding piece 32-3 is provided on one of two radially adjacent turn portions 31n, and the fourth offset protruding piece 32-4 is provided on the other of two radially adjacent turn portions 31n, and the third offset protruding piece 32-3 and the fourth offset protruding piece 32-4 are offset from each other in the circumferential direction. Then, when viewing the turn portion 31n radially outward from the central axis C1 side along the second reference line BL2, the third offset projection 32-3 and the fourth offset projection 32-4 are positioned alternately apart with respect to the second reference line BL2, forming the other side projection group 32g2. Here, the one side projection group 32g1 and the other side projection group 32g2 are point-symmetric with respect to the central axis C1 of the first coil conductor 31 when viewed in the axial direction of the first coil conductor 31.

[0134] Furthermore, the multiple first protruding pieces 32 include a fifth offset protruding piece 32-5 positioned away from the line of symmetry reference line SL in the circumferential direction, and a sixth offset protruding piece 32-6 positioned away from the line of symmetry reference line SL in the circumferential direction. The fifth offset protruding piece 32-5 is provided on one of the radially adjacent turn portions 31n, and the sixth offset protruding piece 32-6 is provided on the other of the radially adjacent turn portions 31n, and the fifth offset protruding piece 32-5 and the sixth offset protruding piece 32-6 are offset from each other in the circumferential direction. When the turn portions 31n are viewed sequentially radially outward from the central axis C1 side along the line of symmetry reference line SL, the fifth offset protruding piece 32-5 and the sixth offset protruding piece 32-6 are positioned alternately away from the line of symmetry reference line SL, forming a third group of protruding pieces 32g3.

[0135] The uniform arrangement of the first protruding pieces 32 as described above makes it possible to more effectively suppress circumferential displacement of the first sheet coil 30 over time. Similarly, the second protruding pieces 42 of the second sheet coil 40 are also uniformly arranged, and circumferential displacement can be effectively suppressed in the same way.

[0136] <Applications of coil units> The coil units 10A to 10E according to the embodiments described above may be used as induction heating coils for induction cookers, or as power transmission and power reception coils in contactless charging, as described above.

[0137] Figure 19 shows an induction cooker 100 equipped with a coil unit 10A. The induction cooker 100 includes a casing 102 containing a top plate 101 on which a metal cooking container such as a pot is placed, a coil unit 10A as an induction heating coil unit, a high-frequency current supply circuit 103, and a cooling fan 104. The induction cooker 100 can generate an induced magnetic field by supplying a high-frequency current from the high-frequency current supply circuit 103 to the coil unit 10A, thereby causing eddy currents to flow through the cooking container and generating heat in the cooking container. Needless to say, any of the coil units 10B to 10E may also be incorporated into the induction cooker.

[0138] Figure 20 schematically shows a wireless power transmission system 110. The wireless power transmission system 110 comprises a power transmission device 111 and a power receiving device 112. The power transmission device 111 includes a coil unit 10A as a power transmission coil and a high-frequency current supply unit 111A. The high-frequency current supply unit 111A supplies high-frequency current to the coil unit 10A as a power transmission coil. The power receiving device 112 includes a coil unit 10A as a power receiving coil and a conversion unit 112A. The conversion unit 112A shapes the high-frequency current generated in the coil unit 10A. The conversion unit 112A has a rectifier circuit and the like that converts the high-frequency current to a DC current. Needless to say, any of the coil units 10B to 10E may be incorporated into the wireless power transmission system.

[0139] The applications of the coil unit according to this embodiment are not limited to induction cookers and wireless power transmission systems. For example, the coil unit according to this embodiment may be used in transformers, DC-DC converters, antennas, and the like.

[0140] While embodiments of this disclosure have been described above, various modifications may be made to the embodiments described above. Such modifications may also fall within the technical scope of this disclosure. [Explanation of Symbols]

[0141] 10A, 10B, 10C, 10D, 10E… Coil Units 20…Base component 21...Base section 21A…main surface 22...Spacer protrusion 30…First sheet coil 31…First coil conductor 31A…Inner peripheral surface 31B…Outer surface 31n, 311~319... Turn section 31cm...Circumference section 31en... Expanded diameter part 32...first protruding piece 32-1…First offset projection 32-2…Second offset projection 32-3…Third offset projection 32-4…Fourth offset projection 32-5…Fifth offset projection 32-6…Sixth offset projection 32g1…One side protruding piece group 32g2…Protruding piece group on the other side 32g3…Third group of protruding segments 33…First lead section 34…Second lead section 40…Second sheet coil 41…Second coil conductor 41n, 411~419... Turn section 41cm...Circumference section 41en...Expanded diameter part 42…Second protruding piece 50...Filled bed 60... Coil intermediate 61...Connection part 80... Carrier component 81…hole 100…Induction heating cooker 110... Wireless power transmission system 111... Power transmission equipment 112... Power receiving device C1...Central axis of the first sheet coil SL…Line symmetry reference line BL1…First reference line BL2…Second reference line

Claims

1. A first sheet coil having a spiral-shaped first coil conductor and a plurality of first protruding pieces provided on the first coil conductor so as to protrude from at least one of the inner circumferential surface of the first coil conductor facing inward in the radial direction perpendicular to the central axis of the first coil conductor and the outer circumferential surface of the first coil conductor facing outward in the radial direction, The system comprises a retaining material for holding the first sheet coil, The first coil conductor includes a plurality of turned portions arranged in the radial direction perpendicular to the central axis of the first coil conductor, The first protruding pieces provided on each of the radially adjacent turn portions are offset from each other in the circumferential direction with respect to the central axis of the first coil conductor. A coil unit in which the first protruding piece is in contact with the retaining material.

2. The plurality of first protruding pieces include a group of one-sided protruding pieces, which include a first offset protruding piece located away from one side in the circumferential direction with respect to the central axis from a first reference line extending radially outward from the central axis so as to intersect the plurality of turn portions, and a second offset protruding piece located away from the first reference line on the other side in the circumferential direction, The coil unit according to claim 1, wherein the first offset projection is provided on one of the radially adjacent turn portions, and the second offset projection is provided on the other of the radially adjacent turn portions.

3. A first sheet coil having a spiral-shaped first coil conductor and a plurality of first protruding pieces provided on the first coil conductor so as to protrude from at least one of the inner circumferential surface of the first coil conductor facing inward in a radial direction perpendicular to the central axis of the first coil conductor and the outer circumferential surface of the first coil conductor facing outward in the radial direction, The system comprises a retaining material for holding the first sheet coil, The first coil conductor includes a plurality of turned portions arranged in the radial direction perpendicular to the central axis of the first coil conductor, The plurality of first protruding pieces include a group of one-sided protruding pieces, which include a first offset protruding piece located away from one side in the circumferential direction with respect to the central axis from a first reference line extending radially outward from the central axis so as to intersect the plurality of turn portions, and a second offset protruding piece located away from the first reference line on the other side in the circumferential direction. The first offset projection is provided on one of the radially adjacent turn portions, and the second offset projection is provided on the other of the radially adjacent turn portions. A coil unit in which the first protruding piece is in contact with the retaining material.

4. The first offset projection is located on a first auxiliary line extending radially outward from the central axis, The coil unit according to claim 2 or 3, wherein the second offset projection is located on a first auxiliary line that is symmetrical with respect to the first auxiliary line on one side with respect to the first reference line.

5. The turn portion is symmetrical with respect to a line symmetric reference line perpendicular to the central axis and the first reference line, and includes a circumferential portion that revolves around the central axis. The plurality of first protruding pieces include a group of other-side protruding pieces, which include a third offset protruding piece located away from one side in the circumferential direction from a second reference line extending radially outward from the central axis in the opposite direction to the first reference line, and a fourth offset protruding piece located away from the other side in the circumferential direction from the second reference line. The coil unit according to any one of claims 2 to 4, wherein the third offset projection is provided on one of the radially adjacent turn portions, and the fourth offset projection is provided on the other of the radially adjacent turn portions.

6. The coil unit according to claim 5, wherein the group of protruding pieces on one side and the group of protruding pieces on the other side are point-symmetric with respect to the central axis of the first coil conductor when viewed in the axial direction of the first coil conductor.

7. The plurality of first protruding pieces include a third group of protruding pieces, which includes a fifth offset protruding piece positioned away from the line of symmetry reference line to one side in the circumferential direction, and a sixth offset protruding piece positioned away from the line of symmetry reference line to the other side in the circumferential direction. The coil unit according to claim 5 or 6, wherein the fifth offset projection is provided on one of the radially adjacent turn portions, and the sixth offset projection is provided on the other of the radially adjacent turn portions.

8. The second sheet coil further comprises a spiral-shaped second coil conductor provided so as to overlap with the retaining material and the first coil conductor, The coil unit according to any one of claims 1 to 7, wherein the second coil conductor includes a plurality of turned portions arranged radially perpendicular to the central axis of the second coil conductor.

9. The coil unit according to claim 8, wherein when the second sheet coil is inverted around a pivot axis perpendicular to the central axis of the second coil conductor, the shape of the second sheet coil matches the shape of the first sheet coil.

10. The first coil conductor includes a plurality of turned portions arranged in the radial direction perpendicular to the central axis of the first coil conductor, The turn portion in the first coil conductor includes a circumferential portion that is an annular in shape with a portion cut out around the central axis of the first coil conductor, The turn portion in the second coil conductor includes a circumferential portion that is annular in shape and partially cut out around the central axis of the second coil conductor, Each of the circumferential portions in the turn portion of the second coil conductor overlaps with any of the circumferential portions in the turn portion of the first coil conductor. The coil unit according to claim 8 or 9, wherein the first protruding piece is provided on the circumferential portion of the turn portion of the first coil conductor.

11. The retaining material is a base member having a base portion and a plurality of spacer protrusions protruding from the base portion. The coil unit according to any one of claims 8 to 10, wherein the first sheet coil is superimposed on the base member such that each of the multiple spacer protrusions contacts one of the multiple first protruding pieces.

12. The coil unit according to any one of claims 8 to 10, wherein the retaining material is a carrier member for embedding the first sheet coil.

13. The coil unit according to claim 12, further comprising a second sheet coil having a spiral-shaped second coil conductor embedded in the carrier member in a state overlapping with the first coil conductor.

14. The coil unit according to claim 13, wherein the carrier member has a hole formed therein that allows the first protruding piece to be exposed to the outside by passing through the space between adjacent turns in the second coil conductor.

15. The coil unit according to any one of claims 12 to 14, wherein the first protruding piece is in contact with the carrier member in a circumferential direction with respect to the central axis of the first coil conductor.

16. A first sheet coil having a spiral-shaped first coil conductor and a plurality of first protruding pieces provided on the first coil conductor so as to protrude from at least one of the inner circumferential surface of the first coil conductor facing inward in a radial direction perpendicular to the central axis of the first coil conductor and the outer circumferential surface of the first coil conductor facing outward in the radial direction, The system comprises a retaining material for holding the first sheet coil, The retaining material is a base member having a base portion and a plurality of spacer protrusions protruding from the base portion. A coil unit in which the first sheet coil is superimposed on the base member such that each of the multiple spacer protrusions contacts one of the multiple first protruding pieces.

17. A second sheet coil further comprising a spiral-shaped second coil conductor provided so as to overlap the retaining material and the first coil conductor, The coil unit according to claim 16, wherein the second coil conductor includes a plurality of turned portions arranged radially perpendicular to the central axis of the second coil conductor.

18. The coil unit according to claim 11 or 17, wherein the spacer projection passes between adjacent turn portions in the second coil conductor.

19. The coil unit according to any one of claims 11, 17, and 18, further comprising a filling layer that fills the space between the first sheet coil and the base portion.

20. A first sheet coil having a spiral-shaped first coil conductor and a plurality of first protruding pieces provided on the first coil conductor so as to protrude from at least one of the inner circumferential surface of the first coil conductor facing inward in a radial direction perpendicular to the central axis of the first coil conductor and the outer circumferential surface of the first coil conductor facing outward in the radial direction, A retaining material for holding the first sheet coil, The second sheet coil comprises the retaining material and a spiral-shaped second coil conductor provided so as to overlap with the first coil conductor, The second coil conductor includes a plurality of turned portions arranged radially perpendicular to the central axis of the second coil conductor, The first protruding piece is in contact with the retaining material, The retaining material is a carrier member into which the first sheet coil and the second sheet coil are embedded. The carrier member has a hole formed therein that allows the first protruding piece to be exposed to the outside by passing through the space between adjacent turns in the second coil conductor, in the coil unit.

21. The coil unit according to claim 20, wherein the first protruding piece is in contact with the carrier member in a circumferential direction with respect to the central axis of the first coil conductor.

22. The coil unit according to any one of claims 17 to 21, wherein when the second sheet coil is inverted around a pivot axis perpendicular to the central axis of the second coil conductor, the shape of the second sheet coil matches the shape of the first sheet coil.

23. The first coil conductor includes a plurality of turned portions arranged in the radial direction perpendicular to the central axis of the first coil conductor, The turn portion in the first coil conductor includes a circumferential portion that is an annular in shape with a portion cut out around the central axis of the first coil conductor, The turn portion in the second coil conductor includes a circumferential portion that is annular in shape and partially cut out around the central axis of the second coil conductor, Each of the circumferential portions in the turn portion of the second coil conductor overlaps with any of the circumferential portions in the turn portion of the first coil conductor. The coil unit according to any one of claims 17 to 22, wherein the first protruding piece is provided on the circumferential portion of the turn portion of the first coil conductor.

24. The coil unit according to any one of claims 1 to 23, wherein the first protruding piece is provided only on the outer circumferential surface of the first coil conductor.

25. A step of preparing a base member having a base portion and a plurality of spacer protrusions protruding from the base portion, A step of preparing a first sheet coil having a spiral-shaped first coil conductor and a plurality of first protruding pieces provided on the first coil conductor so as to protrude from at least one of the inner circumferential surface of the first coil conductor facing inward in the radial direction perpendicular to the central axis of the first coil conductor and the outer circumferential surface of the first coil conductor facing outward in the radial direction, A method for manufacturing a coil unit, comprising the step of stacking a first sheet coil on the base member such that each of the plurality of spacer protrusions contacts one of the plurality of first protruding pieces.

26. A method for manufacturing a coil unit according to claim 25, further comprising the steps of providing a molding material so as to fill the space between the base portion and the first sheet coil and embed the first sheet coil, and curing the molding material.

27. A step of preparing a base member having a base portion and a plurality of spacer protrusions protruding from the base portion, A step of preparing a first sheet coil having a spiral-shaped first coil conductor and a plurality of first protruding pieces provided on the first coil conductor so as to protrude from at least one of the inner circumferential surface of the first coil conductor facing inward in the radial direction perpendicular to the central axis of the first coil conductor and the outer circumferential surface of the first coil conductor facing outward in the radial direction, A step of preparing a second sheet coil having a spiral-shaped second coil conductor, A step of stacking the second sheet coil on the base member such that the second coil conductor is in contact with the base portion and the spacer projection does not interfere with the second coil conductor, A method for manufacturing a coil unit, comprising the step of stacking a first sheet coil on the base member such that each of the plurality of spacer protrusions contacts one of the plurality of first protruding pieces.

28. A method for manufacturing a coil unit according to claim 27, further comprising the steps of providing a molding material so as to fill the space between the base portion and the second coil conductor and the first coil conductor while embedding the first sheet coil and the second sheet coil, and curing the molding material.

29. A method for manufacturing a coil unit according to claim 26 or 28, further comprising the step of removing the base member after the molding material has hardened.

30. An induction cooker comprising a coil unit according to any one of claims 1 to 24 as an induction heating coil unit.

31. A power transmission device comprising a coil unit according to any one of claims 1 to 24 as a power transmission coil.

32. A power receiving device comprising a coil unit according to any one of claims 1 to 24 as a power receiving coil.

33. It comprises a power transmission device and a power receiving device, The power transmission device comprises a coil unit according to any one of claims 1 to 24 as a power transmission coil, and / or A power transmission system wherein the power receiving device comprises a coil unit according to any one of claims 1 to 24 as a power receiving coil.

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