Reactor manufacturing method

Abstract

Improve the reactor's heat dissipation performance and manufacturing costs. [Solution] The product comprises a core 2, a coil 3 wound around the core 2, multiple mounting brackets 4, a primary molded resin part 5 formed by primary injection molding, and a secondary molded resin part 6 formed by secondary injection molding, wherein the core 2 is composed of multiple core members 21, and the coil 3 is composed of an edgewise coil made of rectangular wire wound at a right angle, and the primary molded resin part 5 integrates the multiple core members 21, whose core heat dissipation surface areas 2a are positioned by a primary molding mold 8, and the coil 3, whose coil heat dissipation surface area 3a is positioned by the primary molding mold 8, to form a primary molded product A, and the secondary molded resin part 6 integrates the primary molded product A, whose core heat dissipation surface area 2a and coil heat dissipation surface area 3a are positioned by a secondary molding mold 9, and multiple mounting brackets 4, which are positioned by the secondary molding mold 9.

Description

[Technical Field]

[0001] The present invention relates to a reactor that is integrally molded by injection molding. Manufacturing method Regarding. [Background technology]

[0002] With the trend toward electrification of automobiles, reactors (power inductors) are becoming increasingly important in applications such as high-power battery charging circuits, high-power boost circuits from batteries to motor drives, high-power DC / DC boost circuits in fuel cell vehicles, and high-power compressor drive circuits that operate hydrogen batteries.

[0003] Such reactors for automotive applications operate with high-frequency, large currents, and therefore require a heat dissipation structure with low thermal resistance to the heat sink while maintaining insulation between the coil and core and heat sink, as well as a durable structure that can withstand vehicle vibrations, shocks, heat, etc. for a long period of time.

[0004] In recent years, the mainstream of on-board reactors has been integrally molded using PPS (polyphenylene sulfide) resin or the like (see, for example, Patent Document 1). Components of such integrally molded reactors include multiple core members that make up the core, a coil of rectangular wire wound around the core, a ceramic or plastic gap spacer, a bobbin for assembling the core and coil, and mounting hardware (collars and nuts) for mounting the reactor.

[0005] In the conventional manufacturing of an integrally molded reactor, a primary assembly including multiple core members, coils, and spacers is first formed using a bobbin and adhesive. After the adhesive dries, the primary assembly is placed into an integrally molded mold, and necessary components such as mounting brackets are also placed in the integrally molded mold. The integrally molded reactor is then completed through injection molding. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-243211 Summary of the Invention [Problem to be solved by the invention]

[0007] However, such an integrally molded reactor has room for improvement in terms of heat dissipation performance and manufacturing costs. [Means for solving the problem]

[0008] The present invention has been created in view of the above-mentioned circumstances and with the aim of solving these problems. The invention of claim 1 is a product that is integrally molded by injection molding. , attached to a heat sink A method for manufacturing a reactor, the reactor comprising: a core; a coil wound around the core; to the heat sink a plurality of mounting brackets serving as mounting portions, the core being composed of a plurality of core members; The core member is an E-core integrally including three parallel leg portions and a connecting portion that connects one end of the three leg portions together, and the core is configured by combining two E-cores so that the other end portions of the three leg portions are linearly continuous with each other, The coil is an edgewise coil made by winding a rectangular wire at a right angle. and the heat sink is wound around the middle leg of the core member, and the heat sink comprises a plurality of screw portions to which the mounting bracket is attached, a core cooling portion that cools a core heat dissipation surface area of ​​the core, and a coil cooling portion that cools a coil heat dissipation surface area of ​​the coil, and by attaching the mounting bracket to the screw portions, the core heat dissipation surface area is positioned relative to the core cooling portion and the coil heat dissipation surface area is positioned relative to the coil cooling portion, The method for manufacturing the reactor is to use a primary molding die. The aforementioned a step of forming a primary molded product by integrating, by primary injection molding, a plurality of the core members, each having a core heat dissipation surface area positioned therein, and the coil, each having a coil heat dissipation surface area positioned therein by the primary molding die; and a step of integrating, by secondary injection molding, the primary molded product, each having the core heat dissipation surface area and the coil heat dissipation surface area positioned therein by the secondary molding die, and a plurality of the mounting brackets, each having a core heat dissipation surface area positioned therein by the secondary molding die. the secondary molding die comprises a first surface that contacts the coil heat dissipation surface area of ​​the primary molded product, a second surface that is parallel to the first surface and contacts the core heat dissipation surface area of ​​the primary molded product, and a third surface that is parallel to the first and second surfaces and contacts the lower surfaces of the multiple mounting brackets, the vertical distance between the first surface and the second surface being determined based on the vertical distance between the coil cooling portion and the core cooling portion of the heat sink, and the vertical distance between the first surface and the third surface being determined based on the vertical distance between the coil cooling portion and the screw portion, It is characterized by: [Effects of the Invention]

[0009] Claim 1 of According to the present invention, the positions of the core heat dissipation surface area, the coil heat dissipation surface area, and the mounting bracket are defined with high precision, so that the core heat dissipation surface area and the coil heat dissipation surface area can be positioned with high precision in the heat sink to which the reactor is attached, thereby improving the cooling efficiency of the reactor. 。 [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a perspective view showing a state in which a reactor according to an embodiment of the present invention is attached to a heat sink. [Figure 2] FIG. 2 is an exploded perspective view of FIG. 1. [Figure 3] FIG. 3 is a perspective view of FIG. 2 seen from a different angle. [Figure 4] FIG. 1 is a perspective view showing the components of a primary injection mold. [Figure 5] FIG. 1 is an explanatory diagram of primary injection molding. [Figure 6] FIG. [Figure 7] FIG. 2 is a cross-sectional perspective view of a primary molded product. [Figure 8] FIG. 1 is a perspective view showing components of a secondary injection mold. [Figure 9] FIG. 1 is an explanatory diagram of secondary injection molding. [Figure 10] 10A and 10B are diagrams showing modified cores, where (a) is a diagram showing the core of this embodiment, (b) is a diagram showing the core of a first modified core, (c) is a diagram showing the core of a second modified core, (d) is a diagram showing the core of a third modified core, and (e) is a diagram showing the core of a fourth modified core. DETAILED DESCRIPTION OF THE INVENTION

[0011] [Reactor] 1 to 9, a reactor 1 is integrally molded by injection molding (insert molding), and includes a core 2, a coil 3, a mounting bracket 4, a primary molded resin part 5, and a secondary molded resin part 6.

[0012] 4, the core 2 is made up of multiple core members 21 and has a core heat dissipation surface area 2a that remains exposed even after secondary injection molding. The core member 21 is, for example, an E-core that integrally includes three parallel leg portions 21a to 21c and a connecting portion 21d that connects one end of the legs 21a to 21c, and the core 2 is formed by combining two E-cores so that the other end portions of the legs 21a to 21c are linearly continuous with each other.

[0013] 4 to 7, the coil 3 is wound around the core 2. The coil 3 is configured as an edgewise coil in which a rectangular wire is wound at a right angle, and is wound, for example, around the middle leg 21b of the core member 21. The coil 3 has at least a coil heat dissipation surface region 3a and one end 3b and the other end 3c of the coil 3 as regions that remain exposed even after secondary injection molding.

[0014] The mounting bracket 4 is a member that serves as a mounting portion for the reactor 1, and is formed, for example, by a nut or a collar. For example, as shown in FIGS. 1 to 3, the reactor 1 of this embodiment is intended to be mounted to a heat sink 7 for use, and the mounting bracket 4 includes a plurality of collars. When mounting the reactor 1 to the heat sink 7, a bolt (not shown) is inserted into the collar and screwed into the threaded portion 71 of the heat sink 7.

[0015] The primary molded resin part 5 is formed by primary injection molding. As shown in Fig. 5, the primary molded resin part 5 forms a primary molded product A by integrating a plurality of core members 21, each having a core heat dissipation surface area 2a positioned by a primary molding die 8, with the coil 3, each having a coil heat dissipation surface area 3a positioned by the primary molding die 8.

[0016] The secondary molded resin part 6 is formed by secondary injection molding. As shown in Fig. 7, the secondary molded resin part 6 integrates the primary molded product A, in which the core heat dissipation surface area 2a and the coil heat dissipation surface area 3a are positioned by the secondary molding die 9, with the multiple mounting brackets 4, which are also positioned by the secondary molding die 9, to form the reactor 1.

[0017] With such a reactor 1, the positions of the core heat dissipation surface area 2a, the coil heat dissipation surface area 3a, and the mounting bracket 4 are determined with high precision, so that the core heat dissipation surface area 2a and the coil heat dissipation surface area 3a can be positioned with high precision in the heat sink 7 to which the reactor 1 is assembled, thereby improving the cooling efficiency of the reactor 1.

[0018] For example, the heat sink 7 shown in Figures 1 to 3 has the three screw portions 71 mentioned above, two core cooling portions 72 that cool the core heat dissipation surface area 2a, and a coil cooling portion 73 that cools the coil heat dissipation surface area 3a. By attaching the mounting bracket 4 to the screw portions 71, not only can the core heat dissipation surface area 2a of the reactor 1 be positioned with high precision relative to the core cooling portions 72 of the heat sink 7, but the coil heat dissipation surface area 3a of the reactor 1 can also be positioned with high precision relative to the coil cooling portions 73 of the heat sink 7.

[0019] 1, reference numeral 74 denotes a core heat dissipation sheet sandwiched between the core heat dissipation surface area 2a of the reactor 1 and the core cooling section 72 of the heat sink 7, and reference numeral 75 denotes a coil heat dissipation sheet sandwiched between the coil heat dissipation surface area 3a of the reactor 1 and the coil cooling section 73 of the heat sink 7. In this embodiment, a resin frame 6a is integrally formed with the secondary molded resin part 6 to hold the coil heat dissipation sheet 75 when attaching the reactor 1 to the heat sink 7. Furthermore, an insulating heat dissipation material such as a heat dissipation gap filler (e.g., insulating liquid rubber) may be used instead of the heat dissipation sheets 74 and 75.

[0020] Furthermore, according to the above-described reactor 1, the multiple core members 21 and the coil 3 can be integrated via the primary molded resin part 5, without using a bobbin or adhesive. This reduces the number of parts and manufacturing steps, and makes it possible to significantly reduce the manufacturing cost of the reactor 1.

[0021] [Reactor manufacturing method] Next, a method for manufacturing the reactor 1 will be described with reference to Figures 4 to 9. However, in the drawings, only the main parts of the primary molding die 8 and the secondary molding die 9 are shown.

[0022] The manufacturing method of the reactor 1 includes a primary molding process in which a plurality of core members 21, each having a core heat dissipation surface area 2a positioned by a primary molding mold 8, and a coil 3, each having a coil heat dissipation surface area 3a positioned by the primary molding mold 8, are integrated by primary injection molding to form a primary molded product A, and a secondary molding process in which the primary molded product A, each having a core heat dissipation surface area 2a and a coil heat dissipation surface area 3a positioned by a secondary molding mold 9, and a plurality of mounting brackets 4, each positioned by the secondary molding mold 9, are integrated by secondary injection molding.

[0023] 5, in the primary molding step, first, one core member 21 is set in the primary molding die 8 with its legs 21a to 21c extending upward. Next, the coil 3 is set so that it is wound around the middle leg 21b of the set core member 21. Thereafter, the other core member 21 is placed on top of the one core member 21 with its legs 21a to 21c extending downward.

[0024] 5, the primary molding die 8 includes a fixed part 81 and a plurality of movable parts 82 to 85 that are movable relative to the fixed part 81. The fixed part 81 includes a first surface 81a that abuts against the lower surface of one core member 21 to position the one core member 21 in the up-down direction, a second surface 81b that rises from one end of the first surface 81a and abuts against the core heat dissipation surface area 2a of the one core member 21 to position the one core member 21 in the left-right direction, a third surface 81c that extends to one side from the upper end of the second surface 81b, a fourth surface 81d that rises from one end of the third surface 81c and abuts against the coil heat dissipation surface area 3a of the coil 3 to position the coil 3 in the left-right direction, and a fifth surface (not shown) that abuts against the lower surface of the coil 3 to position the coil 3 in the up-down direction.

[0025] 5 after the two core members 21 and the coil 3 are set in the primary molding die 8, the movable parts 82 to 85 are slid in the directions of the arrows shown in Fig. 5 to abut against predetermined locations of the core members 21 or the coil 3 to position the core members 21 or the coil 3. Specifically, the first movable part 82 abuts against the core heat dissipation surface area 2a of the other core member 21 to position the other core member 21 in the left-right direction, the second movable part 83 abuts against the surface of the other core member 21 opposite the core heat dissipation surface area 2a to position the other core member 21 in the left-right direction, the third movable part 84 abuts against the surface of one core member 21 opposite the core heat dissipation surface area 2a to position the one core member 21 in the left-right direction, and the fourth movable part 85 abuts against the surface of the coil 3 opposite the coil heat dissipation surface area 3a to position the coil 3 in the left-right direction.

[0026] The two core members 21 positioned in this manner within the primary molding die 8 are brought into close contact with each other due to gravity. On the other hand, the two core members 21 and the coil 3 do not come into direct contact with each other due to their dimensional relationship, and a gap of a predetermined dimension is secured between the two core members 21 and the coil 3.

[0027] In the primary molding step, primary injection molding is performed in this positioned state. The resin injected into the primary molding die 8 fills the gaps between the two core members 21 and the coil 3, integrating the two core members 21 with the coil 3. This makes it possible to form a primary molded product A (see FIGS. 6 and 7) in which the two core members 21 and the coil 3 are integrated, without using a bobbin or adhesive.

[0028] As shown in Figure 9, in the secondary molding process, the primary molded product A is set in a secondary molding mold 9 in a positioned state with the coil heat dissipation surface area 3a at the bottom, and then multiple mounting brackets 4 are set in a positioned state, and then secondary injection molding is performed to form the reactor 1.

[0029] The secondary molding die 9 has a first surface 9a that abuts against the coil heat dissipation surface region 3a of the primary molded product A, a second surface 9b that is parallel to the first surface 9a and abuts against the core heat dissipation surface region 2a of the primary molded product A, and a third surface 9c that is parallel to the first surface 9a and the second surface 9b and abuts against the lower surfaces of the multiple mounting brackets 4. The vertical distance L1 between the first surface 9a and the second surface 9b is determined based on the vertical distance between the coil cooling portion 73 and the core cooling portion 72 of the heat sink 7, and the vertical distance L2 between the first surface 9a and the third surface 9c is determined based on the vertical distance between the coil cooling portion 73 and the screw portion 71.

[0030] According to the secondary molding process using such a secondary molding die 9, the positions of the core heat dissipation surface area 2a, the coil heat dissipation surface area 3a, and the mounting bracket 4 are determined with high precision, so that the core heat dissipation surface area 2a and the coil heat dissipation surface area 3a can be positioned with high precision in the heat sink 7 to which the reactor 1 is assembled, thereby improving the cooling efficiency of the reactor 1.

[0031] [Variations] Next, a modified example of the reactor 1 will be described with reference to Fig. 10. However, for configurations common to the above-described embodiment, the same reference numerals as those in the above-described embodiment will be used, and the description of the above-described embodiment may be used.

[0032] As shown in (a) of Figure 10, the core 2 in the above-mentioned embodiment is constructed by combining two core members 21, and all of the legs 21a to 21c are in close contact with each other. However, in order to adjust the impedance characteristics of the reactor 1, the middle leg 21b may be made slightly shorter than the other legs 21a and 21c, and a gap G of a predetermined dimension may be formed between the middle legs 21b, as in the first modified example shown in (b) of Figure 10.

[0033] Furthermore, as shown in Fig. 10(a), in the core member 21 of the embodiment described above, the tip corners of the legs 21a to 21c and the corners of the connecting portion 11d are rounded by cutting out an arc, but they may be cut out at an angle as in a second modified example shown in Fig. 10(c), or may be right-angled without cutting out as in a third modified example shown in Fig. 10(d). The shape of the corners of such core member 21 can be selected as appropriate depending on factors such as ease of manufacture, the desired distribution of leakage magnetic flux, and optimization of inductance saturation characteristics.

[0034] 10(e), a core member 21 having a sub-gap G2 may be applied to the reactor 1. Such a core member 21 is configured, for example, by dividing the middle leg portion 21b and bonding the divided leg portion 21b via a gap spacer.

[0035] The present invention is not limited to the above-described embodiment, and various modifications and variations are possible within the scope of the claims. For example, the number of mounting brackets 4 is not limited to three, but may be four or more. Furthermore, multiple mounting brackets 4 may not be arranged on the same plane, but may be arranged on different planes with steps. [Explanation of symbols]

[0036] 1 reactor 2 cores 2a Core heat dissipation area 21 Core member 3 coils 3a Coil heat dissipation surface area 4 Mounting bracket 5 Primary molded resin part 6 Secondary molded resin part 7 Heatsink 8 Primary molding mold 9 Secondary molding mold A Primary molded product

Claims

[Claim 1] A method for manufacturing a reactor that is integrally molded by injection molding and attached to a heat sink, comprising the steps of: The reactor comprises: The core and a coil wound around the core; a plurality of mounting brackets that serve as mounting portions for the reactor to the heat sink, the core is composed of a plurality of core members, The core member is an E-core integrally including three parallel leg portions and a connecting portion connecting one end of the three leg portions together, and the core is configured by combining two E-cores so that the other end portions of the three leg portions are linearly continuous with each other, The coil is an edgewise coil made by winding a rectangular wire at a right angle, and is wound around the leg portion in the middle of the core member, The heat sink includes a plurality of screw portions to which the mounting bracket is attached, a core cooling portion that cools a core heat dissipation surface area of ​​the core, and a coil cooling portion that cools a coil heat dissipation surface area of ​​the coil, and by attaching the mounting bracket to the screw portions, the core heat dissipation surface area is positioned relative to the core cooling portions and the coil heat dissipation surface area is positioned relative to the coil cooling portions, The method for manufacturing the reactor includes: a step of forming a primary molded product by integrating, by primary injection molding, the plurality of core members, each having a core heat dissipation surface region positioned by a primary molding die, and the coil, each having a coil heat dissipation surface region positioned by the primary molding die; and a step of integrating, by secondary injection molding, the primary molded product in which the core heat dissipation surface area and the coil heat dissipation surface area are positioned by a secondary molding die, and the plurality of mounting brackets positioned by the secondary molding die, The secondary molding die is a first surface that abuts against the coil heat dissipation surface area of ​​the primary molded product; a second surface that is parallel to the first surface and abuts against the core heat dissipation surface area of ​​the primary molded product; a third surface that is parallel to the first surface and the second surface and that abuts against the lower surfaces of the plurality of mounting fixtures, a vertical distance between the first surface and the second surface is determined based on a vertical distance between the coil cooling portion and the core cooling portion of the heat sink; A method for manufacturing a reactor, characterized in that the vertical distance between the first surface and the third surface is determined based on the vertical distance between the coil cooling portion and the threaded portion.

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