Coil unit for contactless power supply

Abstract

To improve the cooling efficiency of a coil.SOLUTION: A coil unit 10 includes a coil portion 20 including a coil 70 formed by winding a conductive wire 71 in a planar shape, and a cooling portion 30 disposed on one side of the coil portion 20. The cooling portion 30 has a flow path 31 through which a refrigerant flows. The cooling portion 30 is made of a material containing ceramics.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a coil unit for contactless power supply. [Background technology]

[0002] The coils used in contactless power transfer have a certain amount of electrical resistance, so a portion of the applied electrical energy is lost and converted into heat. A rise in temperature leads to an increase in the coil's electrical resistance, resulting in a decrease in power transfer efficiency. Naturally, heat generation also has a negative impact not only on the coil but also on surrounding devices. Heat generation can be suppressed by lowering the electrical resistance of the wiring, but there are also factors that increase electrical resistance, such as the proximity effect and the skin effect, making it difficult to suppress heat generation.

[0003] For example, Patent Document 1 discloses a coil unit used for contactless transmission of electric power for running a vehicle. This coil unit includes a coil and a plate-shaped coil holder that holds the coil. The coil holder includes a first spiral passage that is provided along the plate surface of the coil holder and in which conductors that make up the coil are disposed, and a second spiral passage that is provided along the first passage and at a position different from the first passage at least in the direction along the plate surface of the coil holder and in which a coolant is disposed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-85808 Summary of the Invention [Problem to be solved by the invention]

[0005] The coil unit in Patent Document 1 exemplifies a configuration in which the coil holder is made of resin, but the cooling efficiency of the coil is insufficient. Furthermore, if a metal cooling pipe or the like is used, the electromagnetic field from the coil may generate an induced electromotive force, which may cause the coil itself to generate heat. Therefore, a configuration that can cool the coil more efficiently is desired. The present disclosure has been made in view of the above-described circumstances, and aims to provide a coil unit for contactless power supply that can improve the cooling efficiency of the coil. The present disclosure can be realized in the following aspects. [Means for solving the problem]

[0006] [1] A coil portion including a coil formed by winding a conductor in a plane; a cooling unit disposed on one side of the coil unit, the cooling unit has a flow path through which a refrigerant flows, The cooling unit is made of a material containing ceramics. Coil unit for contactless power supply.

[0007] According to the coil unit for contactless power transfer described above in [1], the cooling part is made of a material containing ceramics, which has a relatively high thermal conductivity, thereby enhancing thermal conductivity. Furthermore, if the cooling part were made of a single metal, there would be a risk of heat generation due to induced electromotive force generated by the electromagnetic field from the coil. However, in this coil unit, the cooling part is made of a material containing ceramics, which has a relatively high thermal conductivity and electrical resistance, thereby suppressing such heat generation. Therefore, in this coil unit, the cooling efficiency of the coil can be enhanced.

[0008] [2] The cooling unit has a main body portion having a groove and a lid portion covering the main body portion, The lid portion covers the opening of the groove to form the flow path, The coil unit for contactless power supply described in [1], wherein the main body is made of a material including ceramics.

[0009] According to the coil unit for contactless power supply described in [2] above, it is easier to form grooves than holes in the main body made of a material containing ceramics, so a flow path can be easily formed by forming a groove in the main body and covering the opening of the groove with the lid.

[0010] [3] The coil unit for contactless power supply described in [2], wherein the cover portion is made of a material including ceramics.

[0011] According to the coil unit for contactless power supply described above in [3], the thermal conductivity of the lid portion can be improved compared to when the lid portion is made of resin alone.

[0012] [4] A coil unit for contactless power supply according to [2] or [3], wherein the cover portion is made of a material containing resin.

[0013] According to the coil unit for contactless power supply described above in [4], the adhesion between the main body and the lid can be improved compared to when the lid is made of a single metal or the like.

[0014] [5] The lid portion is made of a material in which ceramic particles are dispersed in a resin matrix, The coil unit for contactless power supply according to any one of [2] to [4], wherein the resin includes a thermosetting resin.

[0015] According to the coil unit for contactless power transfer described above in [5], the lid is made of a material containing a resin matrix, which improves adhesion to the main body. Furthermore, even though the lid has a thermosetting resin matrix, ceramic particles with relatively good thermal conductivity are dispersed therein, which improves the heat dissipation of the cooling unit.

[0016] [6] The ceramic contained in the cooling portion includes at least one selected from the group consisting of alumina, aluminum nitride, silicon nitride, zirconia, and boron nitride; A coil unit for contactless power supply according to any one of [1] to [5].

[0017] According to the coil unit for contactless power supply of [6] above, by using a type of ceramic having a relatively high thermal conductivity, the heat dissipation performance of the cooling part can be further improved.

[0018] [7] The coil portion includes a magnetic material, The ends of the coil are electrode connection portions, the coil, excluding the end portion, is embedded in the magnetic body, and is surrounded by the magnetic body; In at least one cross section perpendicular to the axis of the conductor, the magnetic material fills the spaces between adjacent conductors in a portion of the coil where the conductors are arranged side by side. A coil unit for contactless power supply according to any one of [1] to [6].

[0019] According to the coil unit for contactless power supply described in [7] above, the magnetic field generated from the conductor wire of the coil is less likely to leak from the magnetic body, and the proximity effect between adjacent conductor wires can be suppressed, thereby suppressing an increase in the electrical resistance of the coil.

[0020] [8] A magnetic member and an electromagnetic shielding member are provided in this order on the opposite side of the cooling unit from the coil unit, The complex relative permeability of the magnetic member is greater than the complex relative permeability of the magnetic body. [7] A coil unit for contactless power supply.

[0021] According to the coil unit for contactless power supply described above in [8], the magnetic member can improve the inductance of the coil, and the electromagnetic shielding member can reflect electromagnetic noise that may be generated from the coil and prevent it from leaking to the outside. [Effects of the Invention]

[0022] The present disclosure can provide a coil unit for contactless power supply that can improve the cooling efficiency of the coil. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is an explanatory diagram illustrating a power transmission system according to a first embodiment of the present disclosure. [Figure 2] 4 is a cross-sectional view illustrating a magnetic field generated between a power transmitting coil unit and a power receiving coil unit. FIG. [Figure 3] FIG. 2 is a cross-sectional view of a coil unit. [Figure 4] FIG. [Figure 5] FIG. 2 is a partially perspective plan view of the coil section and the cooling section. [Figure 6] FIG. [Figure 7] 10A to 10C are explanatory views illustrating a manufacturing process of the cooling section. [Figure 8] FIG. 10 is a plan view of a cooling section of the second embodiment. [Figure 9] FIG. 10 is a plan view of a cooling section of a third embodiment. [Figure 10] FIG. 10 is a plan view of a cooling section of a fourth embodiment. [Figure 11] FIG. 11 is a plan view of a cooling section of a fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0024] The present disclosure will be described in detail below. In this specification, when a numerical range is indicated using "-", it is intended to include both the lower limit and the upper limit unless otherwise specified. For example, the expression "10-20" includes both the lower limit "10" and the upper limit "20". In other words, "10-20" has the same meaning as "10 or more and 20 or less". In addition, in this specification, the upper limit and lower limit of each numerical range can be combined in any way.

[0025] First Embodiment 1. Power transmission system 100 Fig. 1 shows an example of a power transmission system 100 according to the first embodiment. The power transmission system 100 is configured as, for example, a system for supplying power wirelessly (contactlessly) to an electric vehicle, a system for supplying power to a mobile terminal (such as a smartphone), or the like. As shown in Fig. 1, the power transmission system 100 includes a power transmitting device 110 and a power receiving device 120. In the power transmission system 100, power is supplied wirelessly (contactlessly) from the power transmitting device 110 to the power receiving device 120.

[0026] The power transmitting device 110 has a coil unit 10 for contactless power supply (hereinafter also simply referred to as the coil unit 10) and a conversion unit 112. The conversion unit 112 is configured as, for example, an inverter. The conversion unit 112 receives power from, for example, a power source (commercial power source, etc.) 114, converts the voltage and frequency, and supplies the power to the coil unit 10.

[0027] The power receiving device 120 has a coil unit 10 and a conversion unit 122. The conversion unit 122 is configured as, for example, an inverter, a rectifier, etc. The conversion unit 122 is supplied with power generated by the coil unit 10, converts AC to DC, and supplies the power to a battery 124. The conversion unit 122 is also supplied with power generated by the coil unit 10, converts the voltage and frequency, and supplies the power to a motor 126.

[0028] When power is supplied wirelessly (contactlessly) from the power transmitting device 110 to the power receiving device 120, a high-frequency current of a predetermined frequency is supplied from the conversion unit 112 in the power transmitting device 110 to the coil unit 10. As shown in Fig. 2, a magnetic field is generated in the coil unit 10 of the power transmitting device 110, and a high-frequency current is generated in the coil unit 10 of the power receiving device 120 due to the influence of this magnetic field. The conversion unit 122 in the power receiving device 120 converts this high-frequency current and supplies it to the battery 124 and the motor 126.

[0029] 2. Coil unit 10 Fig. 3 shows an example of the coil unit 10 of the first embodiment. The coil unit 10 includes a coil section 20, a cooling section 30, a magnetic member 40, an electromagnetic shielding member 50, and a cover 60. Fig. 4 shows an example of the coil section 20. The coil section 20 includes a coil 70 and a magnetic body 80. As shown in Fig. 3, the cooling section 30, the magnetic member 40, and the electromagnetic shielding member 50 are layered on the coil section 20 in this order.

[0030] 2-1. Coil 70 The coil 70 is a planar coil formed by winding a conductor 71 in a plane. The coil 70 has a spiral shape (a planar curve wound in a spiral shape) wound around a central axis C (see FIGS. 3 to 5). The conductors 71 are arranged so as to gradually move away from the central axis C in a radially outward direction from the central axis C. The coil 70 is wound to form a rectangular shape (more specifically, a square shape with rounded corners). The coil 70 has a ring shape as a whole. The coil 70 has a shape in which the conductor 71 is wound, for example, about nine times.

[0031] The coil 70 is made of a conductive material, such as aluminum (Al), an aluminum (Al) alloy, copper (Cu), or a copper (Cu) alloy.

[0032] The coil 70 is, for example, a rectangular wire. That is, the cross-sectional shape of the coil 70 (the cross-sectional shape perpendicular to the axis of the conductive wire 71) is rectangular (more specifically, a rectangle whose length is in the radial direction relative to the central axis C). The coil 70 is, for example, a so-called edgewise coil.

[0033] The size (thickness) of the conductor 71 in a direction parallel to the central axis C is, for example, 0.4 mm to 1.0 mm, e.g., 0.6 mm or 0.8 mm. The size (width) of the conductor 71 in a radial direction (direction perpendicular to the central axis C) is, for example, 5 mm to 70 mm, e.g., 8 mm.

[0034] The spacing between adjacent conductor wires 71 in the portion of coil 70 where conductor wires 71 are lined up next to each other is, for example, constant throughout coil 70. The minimum distance between adjacent conductor wires 71 (the minimum distance between opposing side surfaces) is preferably 0.3 mm or more. The minimum distance between adjacent conductor wires 71 is, for example, 0.2 mm or more and 6 mm or less, e.g., 2.5 mm.

[0035] Ends 72, 73 of the coil 70 (see Figures 3 and 4) serve as electrode connection portions. The ends 72, 73 of the coil 70 are connected to, for example, the conversion units 112, 122, etc. The inner end 72 extends in a direction along the central axis C from the winding portion of the coil 70 that is closest to the central axis C. The outer end 73 extends in a direction along the central axis C from the winding portion of the coil 70 that is closest to the central axis C. The ends 72, 73 extend on the same side (the downward side in Figures 3 and 4) with respect to the plane on which the conductive wire 71 is wound. The ends 72, 73 are bent, for example, at a right angle with respect to the rest of the conductive wire 71.

[0036] The AC resistance of the coil 70 is preferably 30 mΩ or more and 700 mΩ or less.

[0037] Besides the rectangular wire, the coil 70 may be a litz wire (a wire made by twisting together a plurality of conducting wires). For example, the diameter of the litz wire is preferably 20 μm or more and 10000 μm or less, for example, 5 mm.

[0038] 2-2.Magnetic material 80 The magnetic body 80 integrally covers the periphery of the coil 70. The magnetic body 80 is plate-shaped. The shape of the surface of the magnetic body 80 (as viewed in the axial direction of the central axis C) is a quadrangular shape (e.g., a square) with rounded corners. The coil 70, excluding the ends 72 and 73, is embedded in the magnetic body 80 and is surrounded by the magnetic body 80. In at least one cross section perpendicular to the axis of the conductor 71 (e.g., the cross section shown in FIG. 3), the spaces between adjacent conductor wires 71 in the portion of the coil 70 where the conductor wires 71 are lined up next to each other are filled with the magnetic body 80. More specifically, in all cross sections perpendicular to the axis of the conductor wire 71 (all cross sections including the cross section shown in FIG. 3), the spaces between adjacent conductor wires 71 in the portion of the coil 70 where the conductor wires 71 are lined up next to each other are filled with the magnetic body 80. In other words, the magnetic body 80 is sandwiched between adjacent conductor wires 71.

[0039] The magnetic body 80 contains, for example, a resin and soft magnetic particles. The soft magnetic particles are preferably uniformly dispersed within the magnetic body 80. Examples of resins include natural rubber, butyl rubber, nitrile rubber, silicone, acrylic, and polyimide. Among these, silicone is particularly preferred due to its ease of filler mixing and high heat resistance. Furthermore, when silicone is used, it is preferable that the molecular weight be 20,000 or more.

[0040] Examples of soft magnetic particles include Ni-Zn ferrite, Mn-Zn ferrite, magnetite, Fe-Si-B alloy, Fe-Si-B-Cr alloy, Fe-Si alloy, Fe-Si-Cr alloy, sendust, and permalloy. These materials are preferred from the viewpoint of suppressing the electrical resistance of the coil 70 when the coil unit 10 is used with an alternating current of about 85 kHz. When using spherical alloy-based fillers as soft magnetic particles, it is preferable that the particle diameter be 10 μm or more and 50 μm or less, taking into account loss due to eddy currents.

[0041] 3, the magnetic body 80 has holes 81 and 82 for leading out the ends 72 and 73 of the coil 70. The holes 81 and 82 extend in a direction along the central axis C (downward in FIG. 3).

[0042] 2-3. Cooling section 30 The cooling unit 30 cools the coil unit 20 (more specifically, the coil 70) and the like. As shown in FIGS. 3, 5, and 6, the cooling unit 30 has a flow path 31 through which a refrigerant flows. The cooling unit 30 is made of a material containing ceramics. The ceramic contained in the cooling unit 30 preferably contains at least one selected from the group consisting of alumina, aluminum nitride, silicon nitride, zirconia, and boron nitride.

[0043] 3 and 6, the cooling section 30 is, for example, flat. The cooling section 30 is arranged on one side of the coil section 20 (the side opposite to the side that generates a magnetic field, the bottom side in FIG. 3). As shown in FIG. 2, in the coil unit 10 of the power transmitting device 110, the cooling section 30 is arranged on the side of the coil section 20 opposite to the power receiving device 120. In the coil unit 10 of the power receiving device 120, the cooling section 30 is arranged on the side of the coil section 20 opposite to the power transmitting device 110. The cooling section 30 is in contact with one side of the coil section 20 (the bottom side in FIG. 3).

[0044] For example, the shape of the surface of the cooling section 30 (the shape when viewed from the axial direction of the central axis C) is a quadrilateral (for example, a square) with rounded corners. The shape of the surface of the cooling section 30 is the same as the shape of the surface of the coil section 20.

[0045] As shown in FIGS. 3, 5, and 6, a flow path space S1 is formed within the flow path 31. That is, the flow path 31 is a part of the cooling unit 30 that constitutes the flow path space S1. A refrigerant passes through the flow path space S1. The refrigerant is, for example, cooling water, antifreeze, oil, LLC, etc. As shown in FIG. 6, the flow path 31 has a spiral shape (a planar curve wound in a spiral shape) centered on a central axis C. The flow paths 31 are arranged radially outward from the central axis C so as to gradually move away from the central axis C. The flow paths 31 spiral to form a rectangular shape (more specifically, a square shape with rounded corners). The flow path 31 has a ring shape as a whole. The flow path 31 has a spiral shape that spirals around nine times, for example.

[0046] 3, the cross-sectional shape of the flow path space S1 (cross-sectional shape perpendicular to the axis of the flow path 31) is, for example, rectangular (more specifically, a rectangle elongated in the radial direction relative to the central axis C). The interval between adjacent portions of the flow path space S1 is, for example, constant throughout the entire flow path space S1.

[0047] As shown in FIGS. 5 and 6 , the shape of the flow path space S1 is the same as the shape of the coil 70, for example. The cooling unit 30 is arranged so that the flow path space S1 overlaps with the coil 70 in the axial direction of the central axis C. Specifically, the axial direction (spiral direction) of the flow path space S1 is parallel to the axial direction (spiral direction) of the coil 70. More specifically, the axis of the flow path space S1 (spiral direction axis) overlaps with the axis of the coil 70 in the axial direction of the central axis C. The size (width) of the flow path space S1 in the radial direction (direction perpendicular to the central axis C) is the same as the size (width) of the coil 70 in the radial direction (direction perpendicular to the central axis C), for example. Note that the size (width) of the flow path space S1 in the radial direction (direction perpendicular to the central axis C) may be smaller or larger than the size (width) of the coil 70 in the radial direction (direction perpendicular to the central axis C).

[0048] As shown in Figures 3 and 6, the cooling section 30 has a hole 32 formed therein that communicates with the inner end (on the central axis C side) of the flow path 31. The hole 32 extends downward from the inner end of the flow path 31 along the central axis C. The hole 32 is open to the lower surface side of the cooling section 30. A joint 33 is connected to the hole 32. The joint 33 is cylindrical and communicates with the hole 32. The joint 33 is made of, for example, resin.

[0049] As shown in Figures 3 and 6, the cooling section 30 has a hole 34 formed therein, which is connected to the outer end of the flow path 31 (the side opposite the central axis C). The hole 34 extends downward from the outer end of the flow path 31 along the central axis C. The hole 34 is open to the underside of the cooling section 30. A joint 35 is connected to the hole 34. The joint 35 is cylindrical and communicates with the hole 34. The joint 35 is made of, for example, resin.

[0050] The cooling portion 30 is formed with holes 36 and 37 through which the ends 72 and 73 of the coil 70 pass. The holes 36 and 37 are formed at positions that overlap the ends 72 and 73 of the coil 70, respectively, when viewed in the axial direction of the central axis C.

[0051] 6, the hole 32 is located adjacent to the hole 36. When viewed in the axial direction of the central axis C, the hole 32 is located more inward in the flow path 31 than the hole 36 (on the hole 34 side in the circumferential direction of the flow path 31).

[0052] 6, the hole 34 is located adjacent to the hole 37. When viewed in the axial direction of the central axis C, the hole 34 is located more inward in the flow path 31 than the hole 37 (closer to the hole 32 in the circumferential direction of the flow path 31).

[0053] It is preferable that the refrigerant is supplied from the inner end of the flow path 31 and discharged from the outer end of the flow path 31. Specifically, it is preferable that the refrigerant passes through the joint 33, hole 32, flow path space S1, hole 34, and joint 35 in this order. This allows for efficient cooling of the coil 70, which tends to become hotter on the inner side (the side closer to the central axis C).

[0054] As shown in FIG. 3, the cooling unit 30 has a main body 38 having a groove 38A, and a lid 39 that covers the main body 38. The lid 39 covers an opening 38B of the groove 38A to form a flow path 31. The main body 38 is flat. The shape of the surface of the main body 38 (when viewed in the axial direction of the central axis C) is a quadrilateral (for example, a square) with rounded corners. The groove 38A is a recess that is recessed in the axial direction of the central axis C. The lid 39 is flat. The shape of the surface of the lid 39 (when viewed in the axial direction of the central axis C) is a quadrilateral (for example, a square) with rounded corners.

[0055] The main body 38 is preferably made of a material containing ceramics. The ceramic contained in the main body 38 preferably contains at least one selected from the group consisting of alumina, aluminum nitride, silicon nitride, zirconia, and boron nitride.

[0056] The lid portion 39 is preferably made of a material containing ceramic. The ceramic contained in the lid portion 39 preferably contains at least one selected from the group consisting of alumina, aluminum nitride, silicon nitride, zirconia, and boron nitride. The material of the lid portion 39 may contain resin. The lid portion 39 is preferably made of a material in which ceramic particles are dispersed in a resin matrix. The resin preferably contains a thermosetting resin.

[0057] The thermal conductivity of the ceramic contained in the cooling unit 30 is preferably greater than the thermal conductivity of the magnetic member 40, the thermal conductivity of the resin contained in the lid unit 39, and the thermal conductivity of the magnetic body 80. For example, the thermal conductivity of the ceramic contained in the cooling unit 30 is preferably greater than the thermal conductivity of the magnetic member 40. The thermal conductivity of the magnetic member 40 is preferably equal to or greater than the thermal conductivity of the resin contained in the lid unit 39. The thermal conductivity of the resin contained in the lid unit 39 is preferably equal to or greater than the thermal conductivity of the magnetic body 80.

[0058] 2-4. Magnetic member 40 3, the magnetic member 40 is, for example, in the shape of a flat plate. The magnetic member 40 is disposed on the opposite side of the cooling unit 30 from the coil unit 20 (the lower side in FIG. 3). The magnetic member 40 may be in contact with the cooling unit 30, or may be separated from the cooling unit 30 via another member (such as a resin member).

[0059] The complex relative permeability of the magnetic member 40 is preferably greater than the complex relative permeability of the magnetic body 80. The magnetic member 40 is made of, for example, the same material as the soft magnetic particles contained in the magnetic body 80. Examples of the magnetic member 40 include Ni-Zn ferrite, Mn-Zn ferrite, magnetite, Fe-Si-B alloy, Fe-Si-B-Cr alloy, Fe-Si alloy, Fe-Si-Cr alloy, sendust, and permalloy.

[0060] The magnetic member 40 has holes (not shown) through which the ends 72 and 73 of the coil 70 pass, for example. The magnetic member 40 has holes (not shown) through which the joints 33 and 35 pass, for example.

[0061] The magnetic member 40 is larger than the coil portion 20 and the cooling portion 30 in size so as to protrude from the coil portion 20 and the cooling portion 30 when viewed in the axial direction of the central axis C, for example.

[0062] 2-5. Electromagnetic shielding material 50 3, the electromagnetic shielding member 50 is, for example, in the shape of a flat plate. The electromagnetic shielding member 50 is disposed on the opposite side of the magnetic body 80 from the coil portion 20 (the lower side in FIG. 3). The electromagnetic shielding member 50 may be in contact with the magnetic body 80, or may be separated therefrom via another member (such as a resin member).

[0063] The electromagnetic shielding member 50 has a non-magnetic metal layer and is, for example, an aluminum (Al) plate, an aluminum (Al) alloy plate, a copper (Cu) plate, a copper (Cu) alloy plate, or a plate in which aluminum foil or copper foil is attached to a resin plate.

[0064] The electromagnetic shielding member 50 has holes (not shown) through which the ends 72 and 73 of the coil 70 pass, for example. The electromagnetic shielding member 50 has holes (not shown) through which the joints 33 and 35 pass, for example.

[0065] The electromagnetic shield member 50 is larger than the coil portion 20, the cooling portion 30 and the magnetic member 40, for example, when viewed in the axial direction of the central axis C, so as to protrude from the coil portion 20, the cooling portion 30 and the magnetic member 40.

[0066] 2-6. Cover 60 3, the cover 60 covers and integrates the coil unit 20, the cooling unit 30, the magnetic member 40, and the electromagnetic shielding member 50. The cover 60 is made of, for example, a resin material. The cover 60 covers, for example, the other surface (the surface opposite to the cooling unit 30) and side surface of the coil unit 20, the side surface of the cooling unit 30, the entire surface of the magnetic member 40, and one surface of the electromagnetic shielding member 50 (the surface facing the magnetic member 40).

[0067] The cover 60 has holes (not shown) through which the ends 72 and 73 of the coil 70 pass, for example. The cover 60 has holes (not shown) through which the joints 33 and 35 pass, for example.

[0068] 3. Manufacturing method of coil unit 10 A method for manufacturing the coil unit 10 of the present disclosure will be described.

[0069] 3-1. Formation of coil 70 The coil 70 can be formed, for example, by performing laser processing or the like on a metal plate (such as an alloy plate) of a predetermined thickness and punching it into a desired shape.

[0070] 3-2. Formation of magnetic material 80 The magnetic body 80 can be formed, for example, as follows. First, the coil 70 is placed on one side of a first sheet (not shown) containing a magnetic material. Next, the spaces between adjacent conductive wires 71 in the coil 70 are filled with a magnetic material-containing paste. Furthermore, a second sheet (not shown) containing a magnetic material is placed on the side of the coil 70 opposite the first sheet. Thereafter, the magnetic material-containing paste is hardened, and the hardened magnetic material-containing paste is integrated with the first sheet and the second sheet to form the magnetic body 80.

[0071] 3-3. Formation of cooling section 30 The cooling unit 30 can be formed, for example, as follows: The main body 38 can be formed by sintering a plate-shaped ceramic formed body 38X (see FIG. 7(A)) containing ceramic raw materials. The ceramic formed body 38X may be an integrated member corresponding to the entire main body 38.

[0072] Alternatively, ceramic compact 38X may be formed by sintering divided pieces and then joining them together. In this case, it is preferable to seal the vicinity of groove 38A with a water- and oil-resistant adhesive to prevent liquid leakage from the joints. When forming grooves in ceramic compact 38X before sintering, methods such as near-net molding by press molding, extrusion molding, slip casting, injection molding, or gel cast molding, or methods of forming grooves in advance by laminating green sheets are preferred.

[0073] 7(B), the grooves 38A may be formed in advance in the ceramic compact 38X, and the grooves may be formed in the same shape during sintering. Alternatively, the grooves 38A may be formed after the ceramic compact 38X is sintered. In this case, the grooves 38A are preferably formed by blasting, drilling, or the like.

[0074] The lid portion 39 is formed by curing a resin molded body made of a material containing resin. The resin molded body is preferably made of a material in which ceramic particles are dispersed in a resin matrix. The resin preferably contains a thermosetting resin. The thermosetting resin preferably contains polydimethylsiloxane. The ceramic particles are, for example, alumina particles. The resin molded body may also contain a silane coupling agent, a catalyst, a crosslinking agent, etc.

[0075] The resin molded body is in a sheet form. The resin molded body is thermally cured to obtain the lid portion 39 (see FIG. 7(C)). The thermal curing is performed, for example, by heating at 200°C or less. Note that the lid portion 39 may be formed in close contact with the main body portion 38 by thermally curing the resin molded body while the main body portion 38 is covered with the resin molded body.

[0076] Holes 32 and 34 are formed in the lid 39 to allow the refrigerant to flow in and out. Joints 33 and 35 are connected to the holes 32 and 34, respectively. The gap between the hole 32 and the joint 33, and the gap between the hole 34 and the joint 35 are sealed with silicone adhesive to prevent leakage.

[0077] The main body 38 and lid 39 prepared as shown in Figure 7(C) are integrated as shown in Figure 7(D). The gap between the main body 38 and lid 39 may be sealed using a silicone adhesive. The holes 36 and 37 may be formed, for example, after the member corresponding to the main body 38 and the member corresponding to the lid 39 are integrated. Alternatively, the corresponding portions of the holes 36 and 37 may be formed when the main body 38 and the lid 39 are formed, respectively.

[0078] 3-4. Formation of layered structure After forming the magnetic member 40 and the electromagnetic shielding member 50, the coil section 20, the cooling section 30, the magnetic member 40, and the electromagnetic shielding member 50 are stacked together and then covered with the cover 60. In this way, the coil unit 10 is completed.

[0079] 4. Example of Effects of the First Embodiment The coil unit 10 of the first embodiment includes a coil section 20 including a coil 70 formed by planarly winding a conductive wire 71, and a cooling section 30 disposed on one side of the coil section 20. The cooling section 30 has a flow path 31 through which a refrigerant flows. The cooling section 30 is made of a material containing ceramics. According to this coil unit 10, the cooling section 30 is made of a material containing ceramics, which has a relatively high thermal conductivity, thereby enhancing thermal conduction. Furthermore, if the cooling section 30 were made of a single metal, there is a risk of heat generation due to induced electromotive force generated by the electromagnetic field from the coil 70. However, in this coil unit 10, the cooling section 30 is made of a material containing ceramics, which has a relatively high thermal conductivity and electrical resistance, thereby suppressing such heat generation. Therefore, this coil unit 10 improves the cooling efficiency of the coil 70.

[0080] In the coil unit 10 of the first embodiment, the cooling section 30 has a main body 38 having a groove 38A and a lid 39 that covers the main body 38. The lid 39 covers an opening 38B of the groove 38A to form a flow path 31. The main body 38 is made of a material that contains ceramics. According to this coil unit 10, it is easier to form a groove than to form a hole in the main body 38 made of a material that contains ceramics. Therefore, by forming the groove 38A in the main body 38 and then covering the opening 38B of the groove 38A with the lid 39, the flow path 31 can be easily formed.

[0081] In the coil unit 10 of the first embodiment, the lid portion 39 is made of a material containing ceramics. With this coil unit 10, the thermal conductivity of the lid portion 39 can be improved compared to when the lid portion 39 is made of resin alone.

[0082] In the coil unit 10 of the first embodiment, the lid portion 39 is made of a material containing resin. With this coil unit 10, the adhesion between the main body portion 38 and the lid portion 39 can be improved compared to when the lid portion 39 is made of metal alone.

[0083] In the coil unit 10 of the first embodiment, the lid portion 39 is made of a material in which ceramic particles are dispersed in a resin matrix. The resin includes a thermosetting resin. According to this coil unit 10, the lid portion 39 is made of a material that includes a resin matrix, which improves adhesion to the main body portion 38. Furthermore, even though the lid portion 39 has a thermosetting resin matrix, ceramic particles with relatively good thermal conductivity are dispersed therein, which improves the heat dissipation performance of the cooling portion 30.

[0084] In the coil unit 10 of the first embodiment, the ceramic contained in the cooling section 30 includes at least one selected from the group consisting of alumina, aluminum nitride, silicon nitride, zirconia, and boron nitride. According to this coil unit 10, by using a type of ceramic having a relatively high thermal conductivity, the heat dissipation performance of the cooling section 30 can be further improved.

[0085] In the coil unit 10 of the first embodiment, the coil section 20 includes a magnetic body 80. Ends 72 and 73 of the coil 70 are electrode connection sections. The coil 70, excluding the ends 72 and 73, is embedded in the magnetic body 80 and is surrounded by the magnetic body 80. In at least one cross section perpendicular to the axis of the conductor wires 71, the spaces between adjacent conductor wires 71 in the coil 70 where the conductor wires 71 are lined up next to each other are filled with the magnetic body 80. According to this coil unit 10, the magnetic field generated from the conductor wires 71 of the coil 70 is less likely to leak from the magnetic body 80, and the proximity effect between adjacent conductor wires 71 can be suppressed. Therefore, an increase in the electrical resistance of the coil 70 can be suppressed.

[0086] The coil unit 10 of the first embodiment includes a magnetic member 40 and an electromagnetic shielding member 50, in this order, on the side of the cooling unit 30 opposite the coil unit 20. The complex relative permeability of the magnetic member 40 is greater than the complex relative permeability of the magnetic body 80. In this coil unit 10, the magnetic member 40 can improve the inductance of the coil 70. The electromagnetic shielding member 50 can reflect electromagnetic noise that may be generated from the coil 70, preventing it from leaking to the outside.

[0087] Second Embodiment A second embodiment of the present disclosure will be described below with reference to Fig. 8. The coil unit of the second embodiment differs from that of the first embodiment in the shape of the flow path of the cooling section, but is otherwise the same. Note that the same components as those of the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0088] The coil unit of the second embodiment includes a cooling section 230 shown in Fig. 8. The cooling section 230 has a flow path 231 through which a refrigerant flows. A flow path space S2 is formed within the flow path 231. That is, the flow path 231 is a part of the cooling section 230 that constitutes the flow path space S2. The flow path 231 overlaps with the coil 70 in the axial direction of the central axis C.

[0089] Holes 232 and 234 are formed at both ends of the flow path 231. The holes 232 and 234 are open to one surface of the cooling unit 230. The hole 232 is, for example, a supply port for the coolant. The hole 234 is, for example, a discharge port for the coolant.

[0090] The flow path 231 has common paths 231A and 231B and a plurality of branch paths 231C. The common path 231A is formed on one end side of the cooling unit 230 and is, for example, a portion where the refrigerant supplied from the hole 232 spreads. The refrigerant from the common path 231A branches and flows into the plurality of branch paths 231C. The axial directions (directions in which the refrigerant flows) of the plurality of branch paths 231C are parallel. The common path 231B is formed on the other end side of the cooling unit 230 and is, for example, a portion where the refrigerant flowing from the plurality of branch paths 231C join together.

[0091] <Third embodiment> A third embodiment embodying the present disclosure will be described below with reference to Fig. 9. The coil unit of the third embodiment differs from that of the first embodiment in the shape of the flow path of the cooling section, but is otherwise the same. Note that the same components as those of the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0092] The coil unit of the third embodiment includes a cooling section 330 shown in Fig. 9. The cooling section 330 has a flow path 331 through which a refrigerant flows. A flow path space S3 is formed within the flow path 331. That is, the flow path 331 is a part of the cooling section 330 that constitutes the flow path space S3. The flow path 331 overlaps with the coil 70 in the axial direction of the central axis C.

[0093] Holes 332 and 334 are formed at both ends of the flow path 331. The holes 332 and 334 are open to the side surfaces of the cooling unit 330. The hole 332 is, for example, a supply port for the coolant. The hole 334 is, for example, a discharge port for the coolant.

[0094] The flow path 331 has a meandering portion 331A.

[0095] <Fourth embodiment> A fourth embodiment embodying the present disclosure will be described below with reference to Fig. 10. The coil unit of the fourth embodiment differs from that of the first embodiment in the shape of the flow path of the cooling section, but is otherwise the same. Note that the same components as those of the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

[0096] The coil unit of the fourth embodiment includes a cooling section 430 shown in FIG. 10. The cooling section 430 has a plurality of flow paths 431 through which a refrigerant flows. A flow path space S4 is formed within the flow path 431. That is, the flow path 431 is a part of the cooling section 430 that constitutes the flow path space S4. The axial directions of the plurality of flow paths 431 (the direction in which the refrigerant flows) are parallel to each other. The plurality of flow paths 431 overlap with the coil 70 in the axial direction of the central axis C.

[0097] Holes 432 and 434 are formed at both ends of the flow path 431. The holes 432 and 434 are open to the side surface of the cooling unit 430. The hole 432 is, for example, a supply port for the coolant. The hole 434 is, for example, a discharge port for the coolant.

[0098] Fifth Embodiment A fifth embodiment embodying the present disclosure will be described below with reference to Fig. 11. The coil unit of the fifth embodiment differs from that of the first embodiment in the shape of the flow path of the cooling section, but is otherwise the same as that of the first embodiment. Note that the same components as those of the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0099] The coil unit of the fifth embodiment includes a cooling section 530 shown in Fig. 11. The cooling section 530 has a flow path 531 through which a refrigerant flows. A flow path space S5 is formed within the flow path 531. That is, the flow path 531 is a part of the cooling section 530 that constitutes the flow path space S5. The flow path 531 overlaps with the coil 70 in the axial direction of the central axis C.

[0100] Holes 532 and 534 are formed at both ends of the flow path 531. The holes 532 and 534 are open to one surface of the cooling unit 530. The hole 532 is, for example, a supply port for the coolant. The hole 534 is, for example, a discharge port for the coolant.

[0101] The flow path 531 has common paths 531A and 531B and an intersection path 531C. The common path 531A is formed on one end side of the cooling unit 530 and is, for example, a portion where the refrigerant supplied from the hole 532 spreads. The intersection path 531C is a lattice-shaped path where multiple vertical lines and horizontal lines intersect. The refrigerant flows along each line of the intersection path 531C. The common path 531B is formed on the other end side of the cooling unit 530 and is, for example, a portion where the refrigerant flowing in from the intersection path 531C joins. [Example]

[0102] Next, the above embodiment will be described in more detail with reference to examples and comparative examples. Table 1 shows the configurations of the coil units of Examples 1-13 and Comparative Examples 1-6, and the evaluation results.

[0103] [Table 1]

[0104] In Table 1, the column "Flow path shape of cooling section" indicates the planar shape of the flow path (flow path space). For example, "spiral" is the same shape as the flow path 31 of the first embodiment (see FIG. 6). "serpentine" is the same shape as the flow path 331 of the third embodiment (see FIG. 9). "multiple straight lines" is the same shape as the flow path 431 of the fourth embodiment (see FIG. 10). "branching straight lines" is the same shape as the flow path 231 of the second embodiment (see FIG. 8). "lattice" is the same shape as the flow path 531 of the fifth embodiment (see FIG. 11). "none" indicates a solid, flat cooling section with no flow paths. "-" indicates that no cooling section is used.

[0105] In the "Lid Material" column in Table 1, "Alumina Dispersed Silicone" indicates a composition in which alumina particles are dispersed in a silicone matrix. The same is true for "Aluminum Nitride Dispersed Silicone," "Silicon Nitride Dispersed Silicone," and "Boron Nitride Dispersed Silicone."

[0106] In Table 1, the "Coil Type" column indicates the type of coil (material, shape). For example, "Copper Rectangular" indicates that the coil is made of copper (Cu) alloy and is configured as a rectangular wire. "Aluminum Rectangular" indicates that the conductor is made of aluminum (Al) alloy and is configured as a rectangular wire. "Copper Litz" indicates that the conductor is made of copper (Cu) alloy and is configured as a Litz wire (a wire made by twisting together multiple copper wires).

[0107] 1. Fabrication of the coil unit 1-1. Making the coil The rectangular coils were made using copper alloy or aluminum alloy. The coil shape was punched out of an alloy plate of a specified thickness using laser processing. For copper alloys, the coil thickness (size in the direction parallel to the central axis C) was 0.6 mm, and for aluminum alloys, the coil thickness was 0.8 mm. The coil width (size in the direction perpendicular to the central axis C) was 8 mm. The coil turn spacing (the distance between adjacent conductors) was 2.5 mm. The coil winding (number of turns) was 9. When Litz wire was used, the diameter was 5 mm.

[0108] 1-2. Preparation of cooling unit In Example 1, a ceramic molded body before sintering was obtained by stacking green sheets made of alumina. The ceramic molded body was degreased and sintered at 1500°C, after which it was cut and polished to obtain an alumina ceramic plate measuring 350 mm square and 4 mm thick. The obtained ceramic plate was subjected to a blasting process along the spiral coil shape to form a flow path and a main body.

[0109] The surface of the main body where the flow path was formed was covered with a resin molded body made of sheet-like silicone (polydimethylsiloxane) with alumina particles dispersed therein, and the two were integrated. The resin molded body contained a silane coupling agent, a catalyst, and a cross-linking agent. The integrated main body and resin molded body were subjected to a heat treatment at 200°C or less to harden the resin molded body.

[0110] Holes were formed in the lid to allow the refrigerant to flow in and out. Joints were connected to the holes, and the holes and joints were sealed with silicone adhesive to prevent leakage.

[0111] The cooling sections of Examples 2-13 and Comparative Examples 1-5 were also produced in the same manner as in Example 1. The cooling section of Comparative Examples 1-5 did not have a flow path formed therein.

[0112] 1-3.Laminated structure As in the above-mentioned embodiments 1-5, the coil section (a member in which a coil is covered with a magnetic material), the cooling section, the magnetic member, and the electromagnetic shielding member are laminated and covered with a resin cover.

[0113] 2. Evaluation Method The temperature rise when current was passed through the coil was evaluated. The coil unit of the power transmitting device and the coil unit of the power receiving device were placed opposite each other. The distance between the coil units was 175 mm, which is the distance between the surfaces of the resin covers (the surface opposite the coils). Capacitors were connected to each coil to resonate at 85 kHz, and a power transmission test was conducted with the power on the transmitting side set to 4 kW.

[0114] The temperature of the resin cover surface (the surface opposite the coil) of the coil unit of the power receiving device was measured using a thermal camera and recorded as the coil unit temperature. The temperature was measured 2 minutes after operation (start of the test). The refrigerant was antifreeze, and the flow rate was 10 L / min.

[0115] 3. Evaluation Results In Examples 1-13 and Comparative Examples 1-5, the coil unit was equipped with a cooling unit. In Comparative Example 6, the coil unit was not equipped with a cooling unit. In Examples 1-13 and Comparative Examples 1-5, the temperature of the coil unit was 42°C-73°C. In Comparative Example 6, the temperature of the coil unit was 77°C. It is thought that in Examples 1-13 and Comparative Examples 1-5, the coil unit was cooled by the cooling unit, which allowed the temperature rise of the coil unit to be suppressed compared to Comparative Example 6.

[0116] In Example 1-13, a flow path through which the refrigerant flows was formed in the cooling section. In Comparative Example 1-5, a flow path through which the refrigerant flows was not formed in the cooling section. In Example 1-13, the temperature of the coil unit was 42°C-49°C. In Comparative Example 1-5, the temperature of the coil unit was 70°C-73°C. It is thought that in Example 1-13, the flow of the refrigerant in the cooling section was able to further suppress the temperature rise of the coil unit compared to Comparative Example 1-5.

[0117] The results of Examples 1-13 showed that a sufficient cooling effect could be obtained regardless of the shape of the flow path in the cooling section (spiral, serpentine, multiple straight lines, branched straight lines, lattice). It was also found that a sufficient cooling effect could be obtained regardless of the material of the main body (alumina, aluminum oxide, silicon nitride, alumina and zirconia, boron nitride). It was also found that a sufficient cooling effect could be obtained regardless of the material of the lid (alumina-dispersed silicone, aluminum nitride-dispersed silicone, silicon nitride-dispersed silicone, boron nitride-dispersed silicone, alumina, PEEK).

[0118] 4. Effects of the Example According to the above embodiment, the coil unit has improved cooling efficiency of the coil.

[0119] <Other embodiments> The present disclosure is not limited to the embodiments described above and in the drawings. For example, any combination of features of the above-described or following embodiments is possible within a range that does not contradict. Furthermore, any feature of the above-described or following embodiments may be omitted unless explicitly stated as essential. Furthermore, the above-described embodiment may be modified as follows.

[0120] In the first to fifth embodiments, the cooling section is in contact with one surface of the coil section, but it may be in close proximity via a resin member, etc. For example, the cooling section may be spaced about 1 mm from the one surface of the coil section.

[0121] In the first to fifth embodiments, the cooling unit is configured by integrating the main body and lid, which are configured as separate bodies, but may be configured as a single inseparable member.

[0122] In the first to fifth embodiments, the cooling section is configured to be made of a material containing ceramics, but it may also contain metal (for example, metal powder such as copper powder having a relatively high thermal conductivity), resin, etc. The metal powder is preferably powder having a diameter of 50 μm or less.

[0123] In the first to fifth embodiments, the cooling unit is arranged on one side of the coil unit (the side opposite to the side where the magnetic field is generated), but it may be arranged on the other side (the side where the magnetic field is generated, the other coil unit side in the power transmission system 100). In this case, it is preferable that the cooling unit does not contain metal powder. Also, the cooling unit may be arranged on both sides of the coil unit.

[0124] In the first to fifth embodiments, the configuration in which the main body of the cooling unit is disposed on the coil unit side has been exemplified, but the configuration in which the lid of the cooling unit is disposed on the coil unit side may also be used.

[0125] In the first to fifth embodiments, the power transmission system 100 is configured as a system for supplying power wirelessly (contactlessly) to an electric vehicle, but is not limited thereto. For example, the power transmission system 100 may be used in a transformer, a DC-DC converter, an antenna, etc.

[0126] In the first to fifth embodiments, the coil is wound to form a rectangle, but it may be wound to form a circle. Also, the coil is wound to form a square with rounded corners, but it may be wound to form a square with sharp corners.

[0127] In the first to fifth embodiments, the coils may be arranged in multiple stages at intervals in the axial direction.

[0128] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is not limited to the embodiments disclosed herein, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0129] 10: Coil unit for contactless power supply 20: Coil section 30: Cooling section 31: Flow path 32,34: Hole 33,35: Joint 36,37: Hole 38: Main body 38A: Groove 38B: Aperture 38X: Ceramic molding 39: Lid 40: Magnetic materials 50: Electromagnetic shielding material 60: Cover 70: Coil 71: Conductor 72,73: End 80: Magnetic material 81,82: Hole 100: Power transmission systems 110: Power transmission equipment 112,122: Conversion section 114: Power supply 120: Power receiving device 124: Battery 126: Motor 230: Cooling section 231: Channel 231A,231B: Common path 231C: Fork in the road 232,234: Hole 330: Cooling section 331: Channel 331A: Serpentine section 332,334: hole 430: Cooling section 431: Flow path 432,434: Hole 530: Cooling section 531: Flow path 531A, 531B: Common path 531C: Intersection Road 532, 534: Hole C: Central axis S1, S2, S3, S4, S5: Flow space

Claims

1. a coil portion including a coil formed by winding a conductor wire in a planar shape; a cooling unit disposed on one side of the coil unit, the cooling unit has a flow path through which a refrigerant flows, The cooling unit is made of a material containing ceramics. Coil unit for contactless power supply.

2. the cooling unit has a main body portion having a groove and a lid portion covering the main body portion, The lid portion covers the opening of the groove to form the flow path, The coil unit for contactless power supply according to claim 1 , wherein the main body is made of a material containing ceramics.

3. The coil unit for contactless power supply according to claim 2 , wherein the cover portion is made of a material containing ceramics.

4. The coil unit for contactless power supply according to claim 2 , wherein the cover portion is made of a material containing resin.

5. the lid portion is made of a material in which ceramic particles are dispersed in a resin matrix, The coil unit for contactless power supply according to claim 2 , wherein the resin includes a thermosetting resin.

6. The ceramic contained in the cooling portion includes at least one selected from the group consisting of alumina, aluminum nitride, silicon nitride, zirconia, and boron nitride. The coil unit for contactless power supply according to any one of claims 1 to 5.

7. The coil portion includes a magnetic material, The ends of the coil are electrode connection portions, the coil, excluding the end portion, is embedded in the magnetic body, and is surrounded by the magnetic body; In at least one cross section perpendicular to the axis of the conductor, the magnetic material fills the spaces between adjacent conductors in a portion of the coil where the conductors are arranged side by side. The coil unit for contactless power supply according to any one of claims 1 to 5.

8. a magnetic member and an electromagnetic shielding member in this order on an opposite side of the cooling unit from the coil unit, The complex relative permeability of the magnetic member is greater than the complex relative permeability of the magnetic body. The coil unit for contactless power supply according to claim 7.

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