Coil unit and method for manufacturing the same

Abstract

To provide a coil unit including a low-priced and easily wound coil, and a method for manufacturing the coil unit.SOLUTION: The coil unit has a wound coil formed by pressing a metal pipe.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a coil unit and a method for manufacturing the coil unit.

Background Art

[0002] In recent years, wireless power transmission systems that transmit power without contact have been increasingly popular. In the future, the demand for wireless power transmission systems capable of transmitting large amounts of power is expected to increase particularly.

[0003] The coil unit described in Patent Document 1 has been proposed as a solution for suppressing stress concentration due to thermal expansion during energization. This coil unit is used in a non-contact charging system, and the coil is arranged in a spiral shape in a flat coil case. Further, the depth of the coil accommodation groove is set to be larger than the diameter of the coil, and there is a margin to allow bending when the coil thermally expands, and it is described that by doing so, the stress applied to a part of the coil can be dispersed.

[0004] Patent Document 2 provides a coil component for suppressing warping and peeling of a coil. This coil component has a spiral-shaped coil, a first coating layer, and a second coating layer, and the coil is arranged between the first coating layer and the second coating layer. And it is described that the linear expansion coefficients of the first coating layer and the second coating layer are the same.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, the coil described in Patent Document 1 is composed of Litz wire, which is formed by twisting a plurality of wire rods, and the man-hours and costs for manufacturing are too high. The coil described in Patent Document 2 is formed by punching a spiral shape from a copper plate or etching a copper foil into a spiral shape, so a lot of waste materials are generated. The present disclosure relates to a coil unit using a coil that is inexpensive and easily wound, and a method for manufacturing the coil unit.

Means for Solving the Problems

[0007] As a result of intensive studies by the present inventors, it has been found that the above problems can be solved by the means shown below, and the present invention has been achieved. 1. A coil unit including a wound coil, The coil is a crushed metal pipe, the coil unit. 2. The coil unit according to 1 above, wherein the crushed metal pipe is housed in a resin coil case. 3. The coil unit according to 2 above, wherein at least a part of the coil is disposed on the surface layer of a resin coil case. 4. The coil unit according to 3 above, wherein the end portions in the width direction of the coil are gripped by a resin coil case. 5. The resin coil case contains reinforcing fibers, The coil unit according to any one of 2 to 4 above, wherein the weight average fiber length of the reinforcing fibers is 100 mm or less. 6. The resin coil case has a thick-walled portion and a thin-walled portion thinner than the thick-walled portion, and the relationship between the flatness Fa of the resin component and the difference h in thickness between the thick-walled portion and the thin-walled portion is 0 < Fa / h < 1.3. The coil unit according to 5 above. 7. The coil unit according to any one of 1 to 6 above, wherein the coil is wound in a spiral shape in the same plane. 8. The coil unit according to any one of 1 to 7 above, wherein the metal pipe is a copper pipe. 9. The coil unit according to any one of the preceding 1 to 8, wherein the thickness of the coil is 0.01 mm or more and 10 mm or less. 10. A method for manufacturing a coil unit including a coil, wherein the coil is manufactured by winding a metal pipe and then crushing the metal pipe from a direction perpendicular to the winding direction. Method for manufacturing a coil unit. 11. The method for manufacturing a coil unit according to claim 10, wherein the metal pipe is wound in a spiral shape in the same plane. 12. The method for manufacturing a coil unit according to any one of claims 10 or 11, after manufacturing the coil by crushing the metal pipe, by injecting a resin material into the coil and integrally molding it, the coil is housed in a resin coil case. Method for manufacturing a coil unit. 13. The method for manufacturing a coil unit according to claim 12, wherein the resin coil case contains reinforcing fibers, the weight average fiber length of the reinforcing fibers is 100 mm or less, at least a part of the coil is disposed on the surface layer of the resin coil case, and the end of the coil is gripped by the resin coil case. Method for manufacturing a coil unit.

Effect of the Invention

[0008] According to the coil unit and the method for manufacturing a coil unit of the present disclosure, a coil that is inexpensive and easily wound can be used, and unlike conventional coils, no waste material is generated.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

DETAILED DESCRIPTION OF THE INVENTION

[0010] First, embodiments of the present disclosure will be listed and described. A coil unit according to an embodiment of the present disclosure includes a wound coil, and the coil is formed by crushing a metal pipe.

[0011] [Metal pipe] There are various types of metal pipes, which are not particularly limited in the present invention, and general metal pipes can be used.

[0012] The metal material constituting the metal pipe is not particularly limited, and various metals or alloys can be used according to the required properties. Examples of the metal material include copper, aluminum, iron, chromium, nickel, manganese, or alloys thereof. Examples of the metal pipe include the following. (i) Steel pipe: A pipe made of an alloy of iron and steel, which is durable and can withstand high pressure and temperature. (ii) Stainless steel pipe: A pipe made of stainless steel, which has corrosion resistance and is resistant to corrosion and rust. (iii) Copper pipe: A pipe made of copper, which has excellent thermal conductivity and corrosion resistance. (iv) Aluminum pipe: Lightweight and corrosion-resistant, with high thermal conductivity.

[0013] [Winding] 1. Winding method There is no particular limitation on the winding method of the metal pipe. For example, it can be wound as follows. 1.1 Method of winding by hand (i) Cut the pipe to an appropriate length. (ii) Use a file or a rasp to flatten both ends of the pipe. This ensures that the ends of the pipe are firmly connected. (iii) Prepare a tool for winding the pipe. A dedicated tool called a pipe bender is required to wind a metal pipe. The pipe bender consists of a bending head and a handle for bending the pipe. (iv) Bend the pipe using the pipe bender. Attach the bending head of the pipe bender to one end of the pipe and bend the pipe slowly while applying force using the handle. Since the bending angle and the bending position vary depending on the purpose of the pipe to be used and the installation location, it is necessary to confirm the appropriate angle and position. 1.2 Method of winding by machine A dedicated jig can be created and the winding can be done automatically using a machine. For example, if it is to be bent at an angle, a plurality of pins can be provided on a plate and it can be rotated along them. 2. Types of winding There is no particular limitation on the way of winding the metal pipe, and examples include spiral winding, overlap winding, spiral winding, etc. It can also be wound in a spiral shape. When winding in a spiral shape, it can be wound not only in a circular shape (Figure 6A) like a mosquito coil, but also in a polygonal shape such as a square shape or a triangular shape.

[0014] [Crushing] After winding the metal pipe, it is advisable to crush the metal pipe from a direction perpendicular to the winding direction to manufacture a coil.

[0015] The crushing of a metal pipe refers to the phenomenon where the metal pipe deforms due to external pressure or force, the internal space narrows, and the metal pipe collapses. Generally, measures are taken to avoid the crushing of metal pipes. On the other hand, the metal pipe of the present invention forms a coil by actively crushing the pipe. Due to the crushing, the internal space may be completely eliminated, or it may only narrow slightly with a little space remaining.

[0016] When manufacturing a coil, in the case of a litz wire formed by twisting wire rods, the man-hours for twisting are too high. Furthermore, compared to a litz wire, the crushed pipe of the present invention has a higher density, so the space can be effectively utilized, and the thickness of the coil can be reduced. As a result, for example, when arranging the coil unit of the present invention in an automobile, the design space can be expanded.

[0017] Also, when punching or etching a coil from a metal plate, waste materials are generated, and a large amount of unnecessary waste is produced. Especially when trying to manufacture a coil with a large thickness, the productivity drops extremely in etching, and the price soars. In the coil unit according to the present invention, since a metal pipe is used and crushed, it is possible to manufacture a coil in a simple process. Also, depending on the shape of the pipe, it is possible to make the crushing load less than half of the punching load.

[0018] The metal pipe for crushing is preferably a hollow metal pipe. Compared to a solid bar, the hollow metal pipe has a smaller crushing load and bending load. Although a solid metal wire or a solid bar may be used, the hollow metal pipe is easier to wind, so it is easier to manufacture a coil. Also, when manufacturing a coil, after crushing the metal pipe, it is not necessarily required to crush it so that it becomes solid.

[0019] [Thickness of the coil] The thickness of the coil is not particularly limited, but is preferably 0.01 mm or more and 10 mm or less, more preferably 0.05 mm or more and 10.0 mm or less, still more preferably 0.1 mm or more and 8.0 mm or less, and even more preferably 0.1 mm or more and 1.0 mm or less. From the viewpoint of the design freedom of the resin coil case, a thinner coil is preferable. The coil of the present invention is formed by crushing a metal pipe, and the maximum length along the thickness direction in the cross section of the crushed metal pipe is regarded as the thickness of the coil.

[0020] [Storage in a resin coil case] The crushed metal pipe may be housed in a resin coil case. The resin coil case has a thick-walled portion and a thin-walled portion thinner than the thick-walled portion, and at least a part of the coil may be disposed on the outer surface of the resin component along the thin-walled portion (FIG. 3A).

[0021] When the coil unit is manufactured by insert molding, it is preferable to dispose the crushed metal pipe on the surface of the lower mold for molding (FIG. 7). Thereafter, when the resin material is laminated from above and press-molded, when the coil unit is formed, the crushed metal pipe is disposed along the bottom of the thin-walled portion (recessed portion) (FIG. 3A). As shown in FIG. 3A, it is not necessary to completely embed the coil in the resin coil case, and as shown in FIG. 3B, a part of the coil may be embedded.

[0022] The thickness of the resin coil case is not particularly limited. For example, it is preferably 0.1 mm or more and 10 mm or less, more preferably 0.5 mm or more and 10.0 mm or less, and still more preferably 1.0 mm or more and 8.0 mm or less. The thickness of the resin coil case here is the thickness of the thickest part, and more specifically, the maximum thickness of the thick-walled portion.

[0023] [Storage of the coil] There is no particular limitation on the method of storing a coil, which is a crushed metal pipe, in a resin coil case. The coil and the resin coil case may be fastened with bolts, rivets, etc., or an adhesive may be used. However, from the viewpoint of manufacturing efficiency, it is preferable to store the coil in a resin coil unit during the molding process. At this time, it is good to integrally mold by thickening a part of the resin coil case (providing a thick-walled part and a thin-walled part) so as to sandwich the coil. In other words, it is good to integrally mold so as to cover the coil.

[0024] More specifically, it is preferable that the end portion in the width direction of the crushed metal pipe is gripped by a resin coil case. Since the crushed metal pipe is a coil, it can be rephrased that it is preferable to grip the end portion in the width direction of the coil by a resin coil case. For example, FIG. 6A is a schematic diagram of a spiral coil, and FIG. 6B is a cross-section taken along line A-A of FIG. 6A. The state where the end portion in the width direction of the coil (crushed metal pipe) indicated by 601 in FIGS. 6A and 6B is gripped (603 in FIG. 6B) by a resin coil case 602 is shown. By storing the coil with a resin coil case as shown in FIG. 6B, the coil can be prevented from falling off. In particular, when the difference in thermal expansion between the coil and the resin coil case is large, the coil is likely to peel off from the coil case, and storing as depicted in FIG. 6B can effectively prevent the coil from falling off. The method of gripping as shown in FIG. 6 will be described in the section on the manufacturing method.

[0025] [Resin] The resin constituting the coil unit is not particularly limited, and various raw materials can be appropriately selected according to the use of the coil unit, and it may be a thermoplastic resin or a thermosetting resin.

[0026] Examples of thermoplastic resins include vinyl chloride resins, vinylidene chloride resins, vinyl acetate resins, polyvinyl alcohol resins, polystyrene resins, acrylonitrile-styrene resins (AS resins), acrylonitrile-butadiene-styrene resins (ABS resins), acrylic resins, methacrylic resins, polyethylene resins, polypropylene resins, various thermoplastic polyamide resins, polyacetal resins, polycarbonate resins, polyethylene terephthalate resins, polyethylene naphthalate resins, polybutylene naphthalate resins, polybutylene terephthalate resins, polyarylate resins, polyphenylene ether resins, polyphenylene sulfide resins, polysulfone resins, polyether sulfone resins, polyether ether ketone resins, and polylactic acid resins.

[0027] The thermoplastic resin may be a crystalline resin or an amorphous resin. In the case of a crystalline resin, specific preferred crystalline resins include polyamide resins such as nylon 6, polyethylene terephthalate resins, polybutylene terephthalate resins, polyethylene resins, polypropylene resins, polyacetal resins, polyphenylene sulfide resins, and the like. Among them, polyamide resins, polybutylene terephthalate resins, and polyphenylene sulfide resins are preferably used because they are excellent in heat resistance and mechanical strength.

[0028] When using a thermosetting resin, it is preferably one or more resins selected from the group consisting of unsaturated polyester resins, vinyl ester resins, epoxy resins, and phenolic resins. Further, when using a thermosetting resin, it is preferable to produce a resin coil case with a sheet molding compound using reinforcing fibers (sometimes called SMC).

[0029] [Reinforcing fiber: fiber length] The resin coil case contains reinforcing fibers, and the weight average fiber length of the reinforcing fibers is preferably 100 mm or less, more preferably contains discontinuous reinforcing fibers of 1 mm or more and 100 mm or less, and the weight average fiber length Lw of the reinforcing fibers is more preferably 3 mm or more and 80 mm or less, and even more preferably 5 mm or more and 60 mm or less.

[0030] If the weight average fiber length Lw of the reinforcing fibers is 100 mm or less, when manufacturing the resin coil case by press molding, the fluidity of the material is less likely to decrease, and it is easy to create the desired shape. Also, when the weight average fiber length Lw is 1 mm or more, the mechanical strength of the obtained resin coil case is less likely to decrease, which is preferable.

[0031] That is, the reinforcing fibers contained in the coil case of the present invention are preferably discontinuous fibers. When using discontinuous fibers, the formability is improved compared to using only continuous fibers, and it becomes easier to create a complex molded body. Also, by using discontinuous reinforcing fibers, it is difficult for a direction in which the mechanical properties extremely weaken to occur regardless of the direction in which stress is applied to the resin coil case.

[0032] In the case of a molded product made by injection molding, the weight average fiber length of the reinforcing fibers is about 0.1 to 0.3 mm. Therefore, when the weight average fiber length of the reinforcing fibers is 1 mm or more and 100 mm or less, it is preferable to create the molded body by press molding.

[0033] In the present invention, discontinuous reinforcing fibers having different fiber lengths may be used in combination. In other words, the discontinuous reinforcing fibers used in the present invention may have a single peak in the distribution of the weight average fiber length, or may have a plurality of peaks.

[0034] [Measurement method of number average fiber length Ln and weight average fiber length Lw of reinforcing fibers] Generally, if the fiber length of each reinforcing fiber is Li, the number average fiber length Ln and the weight average fiber length Lw are obtained by the following formulas (1) and (2). The units of the number average fiber length Ln and the weight average fiber length Lw are mm. Ln = ΣLi / I ··· Formula (1) Lw = (ΣLi 2 ) / (ΣLi) ··· Formula (2) Here, "I" represents the number of the measured reinforcing fibers.

[0035] When the fiber length is constant, the number average fiber length and the weight average fiber length are the same value. The extraction of the reinforcing fiber from the molded product can be performed, for example, by performing a heat treatment at about 500 °C for 1 hour and removing the resin in the furnace.

[0036] The average fiber length can be obtained, for example, by measuring the fiber lengths of 100 fibers randomly extracted from a resin coil case to the unit of 1 mm using a caliper or the like and based on Formula (1).

[0037] When short fibers that cannot be measured with a caliper are included, after removing the resin, the obtained reinforcing fibers are put into water containing a surfactant and sufficiently stirred by ultrasonic vibration. The stirred dispersion is randomly sampled with a measuring spoon to obtain an evaluation sample, and it is good to measure the lengths of 3000 fibers with an image analyzer Luzex AP manufactured by Nireco Corporation. Using the measured values of the fiber lengths, the number average fiber length Ln and the weight average fiber length Lw can be obtained in the same manner as the above-mentioned Formulas (1) and (2).

[0038] [Reinforcing fiber: Fiber volume ratio] There is no particular limitation on the fiber volume ratio Vf of the reinforcing fiber contained in the resin coil case, but 20 to 70% is preferable, 25 to 60% is more preferable, and 30 to 55% is still more preferable. The fiber volume ratio (unit of Vf: volume%) is the ratio of the volume of the reinforcing fiber to the total volume including not only the reinforcing fiber and the resin but also other additives and the like. There is no limitation on the analysis of the reinforcing fiber volume ratio, but it is good to measure as follows.

[0039] Cut out a sample from the resin coil case, burn and remove the resin in a furnace at 500 °C for 1 hour, and calculate the masses of the reinforcing fiber, resin, and other additives by weighing the sample before and after the treatment. Next, use the specific gravity of each component to calculate the volume ratio of the reinforcing fiber and the resin. Vf = 100 × volume of reinforcing fiber / (volume of reinforcing fiber + volume of resin + volume of other additives)

[0040] [Reinforcing fiber] In this specification, the reinforcing fiber is preferably at least one selected from the group consisting of carbon fiber, aramid fiber, glass fiber, polyester fiber, nylon fiber, polypropylene fiber, and polyethylene fiber. More preferably, the reinforcing fiber is carbon fiber or glass fiber.

[0041] [Reinforcing fiber: Carbon fiber] 1. Carbon fiber in general When using carbon fiber, generally polyacrylonitrile (PAN)-based carbon fiber, petroleum pitch-based carbon fiber, rayon-based carbon fiber, cellulose-based carbon fiber, lignin-based carbon fiber, phenol-based carbon fiber, etc. are known. In the present invention, any of these carbon fibers can be preferably used. Among them, in the present invention, it is preferable to use polyacrylonitrile (PAN)-based carbon fiber in terms of excellent tensile strength. As the PAN-based carbon fiber, for example, the carbon fiber "Tenax" (registered trademark) STS40-24KS (average fiber diameter 7 μm) manufactured by Teijin Limited can be used. 2. Sizing agent for carbon fiber The carbon fiber used in the present invention may have a sizing agent attached to its surface. When using carbon fiber with a sizing agent attached, the type of the sizing agent can be appropriately selected according to the type of carbon fiber and the type of resin used for the X material or Y material, and is not particularly limited.

[0042] [Reinforcing fiber: Glass fiber] The case where the reinforcing fiber used in the present invention is glass fiber will be described. 1. Glass fiber in general Any glass fiber may be used as long as it is generally referred to as glass fiber. The glass compositions such as A glass, C glass, and E glass are not particularly limited, and may contain components such as TiO2, SO3, and P2O5 depending on the case. As the glass fiber, for example, the glass fiber E-glass RS240QR-483 (count: 2400 g / 1000 m) manufactured by Nitto Boseki Co., Ltd. can be used. 2. Sizing Agent for Glass Fiber The glass fiber used in the present invention may have a sizing agent attached to its surface. When using a glass fiber with a sizing agent attached, the type of the sizing agent can be appropriately selected according to the type of the glass fiber and the type of the resin, and is not particularly limited. It is preferable to use a glass fiber that has been pretreated with a conventionally known coupling agent such as an organosilane-based compound, an organotitanium-based compound, an organoborane-based compound, and an epoxy-based compound.

[0043] [Manufacturing Method of Coil Unit] The manufacturing method of the coil unit provided with the coil of the present invention manufactures a coil by crushing a metal pipe from a direction perpendicular to the winding direction after winding the metal pipe. The vertical direction of the paper surface in FIG. 1 is the direction of crushing, and the wound metal pipe spreads in the left-right direction of the paper surface in FIG. 1.

[0044] [Molding of Resin Coil Case] The resin coil case may be a flat resin material, but preferably a fiber-reinforced composite material can be used. When a resin coil case is manufactured by press molding using a flat fiber-reinforced composite material, a coil unit having a thick-walled portion and a thin-walled portion is likely to warp during cooling in the molding process.

[0045] [Shape of Resin Coil Case] When the difference in thickness between the thick-walled part and the thin-walled part of the coil unit is equal to or greater than the thickness of the coil, the coil housed in the coil case is less likely to shift. A coil unit having such a configuration can be manufactured by placing the coil on the surface of the lower molding die 701 and performing molding. Note that it is not necessary for the entire coil to be arranged along the surface of the lower molding die. As long as at least a part of the coil is arranged along the surface of the lower molding die, the position of the coil after molding is less likely to shift.

[0046] [Integral Molding of Coil Case and Crushed Metal Pipe] After manufacturing the coil by crushing the metal pipe, it is preferable to store the coil in a resin coil case by injecting a resin material into the coil and performing integral molding. The integral molding is preferably insert molding.

[0047] 1. Problems in the Storage of Crushed Metal Pipe There is a difference between the thermal shrinkage rate of the coil (crushed metal pipe) and the thermal shrinkage rate of the resin coil case. For example, (i) the difference in molding shrinkage rate when integrally molding a separately described resin coil case and the coil, (ii) the difference in expansion rate / shrinkage rate due to heat generation when electricity is passed through the coil, and (iii) there is a risk that the coil may peel off from the resin coil case due to temperature differences. Furthermore, as the crushed metal pipe in the present invention, one having rounded corners at the ends in the width direction can be used (for example, the schematic diagram of FIG. 1 and the photograph of FIG. 2). When the coil is simply placed in the resin coil case and joined to the resin coil case by adhesion or the like, the ends in the width direction will lift off from the resin coil case. In this case, the coil in the present invention tends to peel off more easily from the resin coil case.

[0048] 2. Storage of Coil by Integral Molding As a solution to the problems in storing the coil, when injecting a resin material into the coil and integrally molding it, it is advisable to fill the resin material into the end of the crushed metal pipe with rounded corners (the region 603 in Fig. 6B). That is, by integrally molding, the end portions in the width direction of the coil (crushed metal pipe) can be gripped by the resin coil case. Thereby, it is possible to prevent the coil from falling off the coil case.

[0049] 3. An example of a method for manufacturing a coil unit Next, a method for manufacturing a coil unit according to an embodiment of the present disclosure will be described. When manufacturing a coil unit, it is advisable to use a mold having an upper mold and a lower mold.

[0050] Fig. 7 depicts an example of a mold when manufacturing a coil unit in which a coil is embedded in a resin coil unit. As shown in Fig. 7, the coil 703 is disposed on the surface of the lower mold 701. The coil 703 depicted in Fig. 7 is a crushed metal pipe and typically has the same shape as the coil after molding. Next, a heated flat resin material 705 (preferably a thermoplastic resin material containing reinforcing fibers) is placed between the upper mold 702 and the lower mold 701, and the mold 704 is closed to perform compression molding. The mold temperature is below the solidification temperature of the thermoplastic resin when the resin is a thermoplastic resin. In this compression molding process, the resin material flows according to the coil shape to form a thickness deviation portion. Also, it can be formed so that the end portions in the width direction of the coil 703 are gripped. This is because the crushed metal pipe has rounded corners as shown in Fig. 1. Thereafter, by opening the mold 704 and taking out the coil unit, a coil unit in which the coil and the resin coil case are integrated is obtained.

[0051] The coil unit formed in this way has a resin coil case and a coil. The resin coil case has a thick-walled portion and a thin-walled portion thinner than the thick-walled portion. The coil is disposed at least partially on the surface layer of the resin coil case (more specifically, at least a part of the coil is embedded in the resin coil case). Furthermore, the end portions in the width direction of the coil are gripped by the resin coil case. In FIG. 7, the resin material 705 is located above the coil. However, if the obtained coil unit is inverted upside down, it coincides with the configuration of the coil unit shown in FIG. 3A.

[0052] When forming the coil unit by compression molding, the charging rate of the resin material 705 is preferably 90% or more, more preferably 95% or more, and still more preferably 99% or more. The upper limit of the charging rate is not particularly limited and may exceed 100%, but is preferably 100% or less in order to reduce the amount of waste material. The charging rate of the resin material during compression molding is the ratio (A2 / A1) of the area A2 of the resin material placed in the mold 704 before molding to the area A1 of the coil unit in a plan view. When the charging rate is high, the in-plane flow of the matrix resin is suppressed, so that the unevenness of the fiber ratio of the resin coil unit after molding can be reduced. Although the mode of compression molding the resin material has been described, it may be formed by other molding methods such as injection molding.

[0053] [Flatness of the resin coil case] In a cross-sectional view perpendicular to the outer surface of the resin coil case, the thick-walled portion and the thin-walled portion may be alternately located. According to the coil unit of the present invention, the crushed metal pipe can be disposed evenly on the resin coil case. The "cross-section perpendicular to the outer surface of the resin coil case" is not uniquely determined, but the case where the thick-walled portion and the thin-walled portion are alternately located in any cross-sectional view perpendicular to the outer surface of the resin coil case is regarded as "in a cross-sectional view perpendicular to the outer surface of the resin coil case, the thick-walled portion and the thin-walled portion are alternately located".

[0054] It is preferable that the relationship between the flatness Fa of the resin coil case and the difference h in thickness between the thick-walled portion 402 and the thin-walled portion 403 is 0 < Fa / h < 1.3. With such a coil unit, the lifting of the metal pipe crushed from the resin coil case can be further reduced, and it becomes easier to combine with other components.

[0055] [Flatness of the resin coil case: when integrally molded] (1) Difference in shrinkage rate When manufacturing a coil unit by integrally molding a resin material and a crushed metal pipe, since it is heated during molding and then cooled to room temperature, each component constituting the coil unit shrinks during cooling. In the case of a coil unit having a resin coil case and a crushed metal pipe, generally, since the thermal expansion coefficient of the crushed metal pipe is larger than that of the resin coil case, the crushed metal pipe shrinks more than the resin coil case. More specifically, since the temperature of the resin material to be introduced is higher than the temperature of the coil, the amount of shrinkage is larger for the resin material.

[0056] (2) Reduction of lifting due to warping of the resin coil case The resin coil case has a thick-walled portion and a thin-walled portion thinner than the thick-walled portion. In a cross-sectional view perpendicular to the outer surface of the resin coil case, when the thick-walled portion and the thin-walled portion are alternately positioned, it is preferable that the relationship between the flatness Fa of the resin coil case, the flatness Fa of the resin component, and the difference h in thickness between the thick-walled portion and the thin-walled portion is 0 < Fa / h < 1.3. The flatness Fa is defined by the following steps 1 to 5. (Step 1) The resin coil case is placed stationary so that the surface of the outer surface of the thick-walled portion 402 where the crushed metal pipe is disposed (hereinafter sometimes simply referred to as the "disposing surface") is on the lower side. (Step 2) Observe the cross-section of the resin coil case 401 in a cross-sectional view where the thick-walled portion 402 and the thin-walled portion 403 are alternately positioned. Cut out the observation range of the resin coil case 401 so that the length Ly along the direction in which the thick-walled portion 402 and the thin-walled portion 403 are alternately positioned is 40 cm. (Step 3) Pay attention to the lower surface of the resin coil case. (Step 4) Draw two parallel ideal straight lines with the minimum necessary vertical width so as to cover the entire surface. (Step 5) Define the distance between the two ideal straight lines drawn in Step 4 as flatness Fa.

[0057] Steps 1 to 5 will be described with reference to FIGS. 4A and 4B. Note that FIGS. 4A and 4B are drawn on the premise that the crushed metal pipe is arranged at the thin portion 403.

[0058] FIG. 4A shows a resin coil case 401 placed stationary with the arrangement surface of the uneven wall portion 402 facing downward. The uneven wall portion 402 and the thin portion 403 are alternately located along the Y-axis direction in FIG. 4A. The Z-axis direction is the thickness direction of the resin coil case 401. FIG. 4A is a view showing a cross section by the Y-Z plane, in which the observation range of the resin coil case 401 is cut out so that the length Ly along the Y-axis direction is 40 cm (Step 2). Pay attention to the lower surface of the resin coil case on the lower side of the paper surface (Steps 3 and 405 in FIG. 4).

[0059] The two parallel ideal straight lines are illustrated by 404 in FIG. 4A. The two parallel ideal straight lines 404 are drawn so that the distance between them is minimized. In other words, two parallel ideal straight lines 404 are drawn with the minimum necessary vertical width (Step 4). Note that the method of observing and measuring in a state where the top and bottom of the resin coil case in FIGS. 4A and 4B are reversed and the surface of the opposite side of the coil arrangement surface (405 in FIG. 4B) in the resin coil case is in contact with the table is not adopted in the present disclosure.

[0060] When the flatness Fa varies depending on the observation range, if there is a portion that satisfies 0 < Fa / h < 1.3 even at one point, it is regarded that 0 < Fa / h < 1.3 is satisfied on the arrangement surface of the uneven wall portion 402.

[0061] The thickness difference h between the thick part 402 and the thin part 403 indicates the depth of the groove when observing the cross-section where the thick part 502 and the thin part 503 are alternately positioned, as illustrated in FIG. 5. When the height h of the resin component 501 varies depending on the measurement position, if h satisfies 0 < Fa / h < 1.3 at at least one measurement position, it is regarded that 0 < Fa / h is satisfied on the placement surface of the thick part 502.

[0062] When Fa / h = 0, the placement surface where the coil is arranged is a completely flat plane, that is, an ideal plane. When the placement surface of the thick part 502 satisfies 0 < Fa / h, it means that the resin coil case is warped so as to be convex toward the coil. If 0 < Fa / h, the coil can be pulled in the plane direction of the resin coil case (the Y direction in FIG. 4A), and the floating of the coil from the resin coil case can be further reduced.

[0063] If Fa / h < 1.3, it is easy to combine with other components. For example, the assembly of an automobile is easy. More preferably, 0 < Fa / h ≤ 1.0, still more preferably 0 < Fa / h ≤ 0.7, even more preferably 0 < Fa / h ≤ 0.4, and most preferably 0 < Fa / h ≤ 0.1.

[0064] The preferred value of Fa is 0 mm or more and less than 30 mm, more preferably more than 0 mm and less than 20 mm, still more preferably more than 0 mm and less than 15 mm, even more preferably more than 0 mm and less than 10 mm, and most preferably more than 0 mm and less than 5 mm.

[0065] The preferred value of h is more than 0 mm and less than 30 mm, more preferably more than 0 mm and less than 20 mm, still more preferably more than 0 mm and less than 15 mm, even more preferably more than 0 mm and less than 10 mm, and most preferably more than 0 mm and less than 5 mm.

[0066] [Shape of Resin Coil Unit] The resin coil case has a substantially flat plate shape as shown by 301 in FIG. 3 for example. The resin coil case has a thickened portion (302) and a thinner portion (303) thinner than the thickened portion (302). A convex portion corresponding to the thickened portion 302 is provided on one main surface (the upper surface in FIG. 3A) of the resin coil case 301, and the other main surface (the lower surface in FIG. 3A) is flat. In the present disclosure, the thickened portion 302 refers to a portion that is thickened with respect to the entire resin coil case 301, and the thickened portion 302 itself may have a uniform thickness.

[0067] [Crushed metal pipe housed in a resin coil unit] The crushed metal pipe 304 is disposed on the outer surface of the resin coil case 301. The crushed metal pipe 304 is arranged in a spiral shape on the main surface of the resin coil case 301 and is configured to widely cover the main surface of the resin coil case 301.

[0068] As described above, the present disclosure has been described along specific embodiments, but the present disclosure is not limited to these contents.

Industrial Applicability

[0069] The coil unit and the method for manufacturing the coil unit of the present disclosure are used in many different applications and are not particularly limited, but some of them are shown below. 1. Electromagnetic induction For example, it can be used for electromagnetic induction. This is often used to generate electromagnetic waves and is used in applications such as wireless communication, power transmission, or electromagnetic induction cookers. 2. Electronic devices For example, it can be generally used in electronic devices. These control the flow of current and enable the operation of specific electronic devices. For example, they are used in devices such as televisions, radios, and computers. 3. Power conversion For example, it can be generally used in power conversion devices (for example, transformers, inverters, converters). These devices convert power from one form to another. 4. Motors and Generators For example, it can be used in motors and generators. These devices convert electrical energy into mechanical energy or vice versa.

Explanation of Symbols

[0070] 301, 401, 501, 602: Resin Coil Cases 302, 402, 502: Concentric Part 303, 403, 503: Thin Part 304, 601: Crushed Metal Pipe (Coil) 404: Two Parallel Ideal Straight Lines 405: Coil Arrangement Plane in Resin Coil Case 603: Gripping Part 701: Lower Mold 702: Upper Mold 703: Coil 704: Molding Die 705: Resin Material

Claims

1. A coil unit comprising a wound coil, wherein the coil is formed by crushing a metal pipe, the coil unit.

2. The coil unit according to claim 1, wherein the crushed metal pipe is housed in a resin coil case.

3. The coil unit according to claim 2, wherein at least a part of the coil is disposed on the surface layer of a resin coil case.

4. The coil unit according to claim 3, wherein the end portions in the width direction of the coil are gripped by a resin coil case.

5. The resin coil case contains reinforcing fibers, The coil unit according to any one of claims 2 to 4, wherein the weight average fiber length of the reinforcing fibers is 100 mm or less.

6. The resin coil case has a thick-walled portion and a thin-walled portion thinner than the thick-walled portion, and the relationship between the flatness Fa of the resin component and the difference h in thickness between the thick-walled portion and the thin-walled portion is 0 < Fa / h < 1.

3. The coil unit according to claim 5.

7. The coil unit according to any one of claims 1 to 6, wherein the coil is wound in a spiral shape in the same plane.

8. The coil unit according to any one of claims 1 to 7, wherein the metal pipe is a copper pipe.

9. The coil unit according to any one of claims 1 to 8, wherein the thickness of the coil is 0.01 mm or more and 10 mm or less.

10. A method for manufacturing a coil unit provided with a coil, wherein the coil is manufactured by winding a metal pipe and then crushing the metal pipe from a direction perpendicular to the winding direction. A method for manufacturing a coil unit.

11. The method for manufacturing a coil unit according to claim 10, wherein the metal pipe is wound in a spiral shape in the same plane.

12. A method for manufacturing a coil unit according to any one of claims 10 or 11, after manufacturing the coil by crushing the metal pipe, by injecting a resin material into the coil and integrally molding it, the coil is housed in a resin coil case, A method for manufacturing a coil unit.

13. The method for manufacturing a coil unit according to claim 12, wherein the resin coil case contains reinforcing fibers, and the weight average fiber length of the reinforcing fibers is 100 mm or less, A method of manufacturing a coil unit, wherein at least a part of the coil is disposed on a surface layer of a resin coil case, and an end portion of the coil is gripped by the resin coil case.

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