Reactor manufacturing method

Abstract

To improve the heat dissipation performance and manufacturing cost of the reactor. [Solution] The device comprises a core 2, a coil 3 wound around the core 2, a plurality of 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. The core 2 is composed of a plurality of core members 21, and the coil 3 is composed of an edgewise coil made by winding a flat wire at a right angle. The primary molded resin part 5 integrates a plurality of core members 21 whose core heat dissipation surface region 2a is positioned by a primary mold 8, and a coil 3 whose coil heat dissipation surface region 3a is positioned by a primary mold 8 to form a primary molded product A. The secondary molded resin part 6 integrates the primary molded product A, whose core heat dissipation surface region 2a and coil heat dissipation surface region 3a are positioned by a secondary mold 9, and a plurality of mounting brackets 4 positioned by a secondary mold 9.

Description

Technical Field

[0001] The present invention relates to a reactor integrally formed by injection molding.

Background Art

[0002] Reactors (power inductors) are becoming increasingly important in applications such as the high-power charging circuit of batteries, the high-power boost circuit from batteries to motor drives, the high-power DC / DC boost circuit of fuel cell vehicles, and the high-power compressor drive circuit for operating fuel cells, with the electrification of automobiles.

[0003] Such in-vehicle reactors operate with high-frequency large currents, so a heat dissipation structure with low thermal resistance to the heat sink while maintaining insulation between the coil and the core or heat sink, and a durability structure that can withstand vehicle vibrations, impacts, heat, etc. for a long time are required.

[0004] In recent years, in-vehicle reactors, integral molding with PPS (polyphenylene sulfide) resin, etc. has become the mainstream (for example, see Patent Document 1). The component parts of such integral molding reactors include a plurality of core members constituting the core, a flat wire coil wound around the core, a ceramic or plastic gap spacer, a bobbin for assembling the core and the coil, mounting brackets (collars and nuts) for mounting the reactor, etc.

[0005] In the conventional manufacture of integral molding reactors, first, a primary assembly including a plurality of core members, a coil, and a spacer is formed using a bobbin and an adhesive. After the adhesive dries, the primary assembly is placed in an integral molding die, and at the same time, necessary parts such as mounting brackets are also set in the integral molding die, and then injection molding is carried out to complete the integral molding reactor.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

[0007] However, there is room for improvement in terms of heat dissipation performance and manufacturing costs with such one-piece molded reactors. [Means for solving the problem]

[0008] The present invention was created in view of the above circumstances and with the aim of solving these problems, and the invention of claim 1 is a reactor integrally molded by injection molding, comprising a core, a coil wound around the core, a plurality of mounting brackets that serve as mounting parts for the reactor, a primary molded resin part formed by primary injection molding, and a secondary molded resin part formed by secondary injection molding, wherein the core is composed of a plurality of core members and has a core heat dissipation surface region that remains exposed even after the secondary injection molding, and the coil is an edgewise coil made by winding a flat wire at a right angle The primary molded resin part is characterized by integrating a plurality of core members whose core heat dissipation surface region is positioned by a primary mold and a coil whose coil heat dissipation surface region is positioned by the primary mold, to form a primary molded product, and the secondary molded resin part is characterized by integrating the primary molded product whose core heat dissipation surface region and coil heat dissipation surface region are positioned by a secondary mold and a plurality of mounting brackets positioned by the secondary mold. Furthermore, the invention of claim 2 is a reactor according to claim 1, characterized in that the plurality of core members and the coil are integrated via the primary molded resin portion without the use of a bobbin and adhesive. Furthermore, the invention of claim 3 is a method for manufacturing a reactor integrally molded by injection molding, wherein the reactor comprises a core, a coil wound around the core, and a plurality of mounting brackets that serve as mounting parts for the reactor, the core being composed of a plurality of core members, and the coil being composed of an edgewise coil wound at right angles on a flat wire, and the method for manufacturing the reactor is characterized by comprising the steps of forming a primary molded product by integrating a plurality of the core members, whose core heat dissipation surface region is positioned by a primary molding die, and the coil, whose coil heat dissipation surface region is positioned by the primary molding die, by primary injection molding, and integrating the primary molded product, whose core heat dissipation surface region and the coil heat dissipation surface region are positioned by a secondary molding die, and a plurality of the mounting brackets positioned by the secondary molding die, by secondary injection molding. [Effects of the Invention]

[0009] According to the invention of claim 1 or 3, the positions of the core heat dissipation surface area, the coil heat dissipation surface area, and the mounting bracket are precisely defined, so that in a heat sink to which a reactor is assembled, the core heat dissipation surface area and the coil heat dissipation surface area can be precisely positioned, thereby improving the cooling efficiency of the reactor. Furthermore, according to the invention of claim 2, since the multiple core members and coils are integrated via a primary molded resin part without the use of bobbins and adhesives, the number of parts and manufacturing processes can be reduced, and the manufacturing cost of the integrally molded reactor can be significantly reduced. [Brief explanation of the drawing]

[0010] [Figure 1] This is a perspective view showing a reactor according to an embodiment of the present invention mounted on a heatsink. [Figure 2] Figure 1 is an exploded perspective view. [Figure 3] Figure 2 is a perspective view from a different angle. [Figure 4] This is a perspective view showing the components of a primary injection molded part. [Figure 5] This is an explanatory diagram of primary injection molding. [Figure 6]This is a perspective view of the primary molded product. [Figure 7] This is a cross-sectional perspective view of the primary molded product. [Figure 8] This is a perspective view showing the components of a secondary injection molding process. [Figure 9] This is an explanatory diagram of secondary injection molding. [Figure 10] This diagram shows modified versions of the core, where (a) shows the core of this embodiment, (b) shows the core of the first modified version, (c) shows the core of the second modified version, (d) shows the core of the third modified version, and (e) shows the core of the fourth modified version. [Modes for carrying out the invention]

[0011] [Reactor] Embodiments of the present invention will be described below with reference to the drawings. In Figures 1 to 9, 1 is a reactor integrally molded by injection molding (insert molding), and the reactor 1 comprises a core 2, a coil 3, a mounting bracket 4, a primary molded resin part 5, and a secondary molded resin part 6.

[0012] As shown in Figure 4, the core 2 is composed of a plurality of core members 21 and has a core heat dissipation surface region 2a that remains exposed even after secondary injection molding. The core member 21 is, for example, an E-core integrally comprising three parallel leg portions 21a to 21c and a connecting portion 21d that connects one end of each leg portion 21a to 21c. The core 2 is constructed by combining two E-cores such that the other ends of the leg portions 21a to 21c are linearly continuous.

[0013] As shown in Figures 4 to 7, the coil 3 is wound around the core 2. The coil 3 is made of an edgewise coil, which is made by winding a flat wire at a right angle, and is wound around, for example, the intermediate leg portion 21b of the core member 21. The coil 3 also has at least a coil heat dissipation surface region 3a and one end 3b and the other end 3c of the coil 3, which remain exposed even after secondary injection molding.

[0014] The mounting fitting 4 is a member that serves as the mounting portion of the reactor 1 and is composed of, for example, nuts and collars. For example, as shown in FIGS. 1 to 3, the reactor 1 of the present embodiment is assumed to be used by being attached to the heat sink 7, and the mounting fitting 4 includes a plurality of collars. When attaching the reactor 1 to the heat sink 7, a bolt (not shown) is inserted through the collar and threaded into the threaded portion 71 of the heat sink 7.

[0015] The primary molded resin portion 5 is formed by primary injection molding. As shown in FIG. 5, the primary molded resin portion 5 integrally forms a plurality of core members 21 in which the core heat dissipation surface region 2a is positioned by the primary molding die 8 and a coil 3 in which the coil heat dissipation surface region 3a is positioned by the primary molding die 8 to form a primary molded product A.

[0016] The secondary molded resin portion 6 is formed by secondary injection molding. As shown in FIG. 7, the secondary molded resin portion 6 integrally forms the primary molded product A in which the core heat dissipation surface region 2a and the coil heat dissipation surface region 3a are positioned by the secondary molding die 9 and a plurality of mounting fittings 4 positioned by the secondary molding die 9 to form the reactor 1.

[0017] According to such a reactor 1, since the positions of the core heat dissipation surface region 2a, the coil heat dissipation surface region 3a, and the mounting fitting 4 are defined with high precision, in the heat sink 7 to which the reactor 1 is assembled, the core heat dissipation surface region 2a and the coil heat dissipation surface region 3a can be arranged with high precision, and the cooling efficiency of the reactor 1 can be improved.

[0018] For example, the heat sink 7 shown in FIGS. 1 to 3 includes the three threaded portions 71 described above, two core cooling portions 72 for cooling the core heat dissipation surface region 2a, and a coil cooling portion 73 for cooling the coil heat dissipation surface region 3a. By attaching the mounting fitting 4 to the threaded portion 71, not only can the core heat dissipation surface region 2a of the reactor 1 be arranged with high precision with respect to the core cooling portion 72 of the heat sink 7, but also the coil heat dissipation surface region 3a of the reactor 1 can be arranged with high precision with respect to the coil cooling portion 73 of the heat sink 7.

[0019] In Figure 1, 74 is 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 75 is 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 in the secondary molded resin part 6 to hold down the coil heat dissipation sheet 75 when the reactor 1 is attached to the heat sink 7. Alternatively, an insulating heat dissipation material such as a heat gap filler (for example, insulating liquid rubber) may be used instead of the heat dissipation sheets 74 and 75.

[0020] Furthermore, according to the reactor 1 described above, the multiple core members 21 and coil 3 can be integrated via the primary molded resin part 5 without the need for bobbins or adhesives. This reduces the number of parts and manufacturing processes, making it possible to significantly reduce the manufacturing cost of the reactor 1.

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

[0022] The method for manufacturing the reactor 1 comprises a primary molding step of integrating a plurality of core members 21, whose core heat dissipation surface regions 2a are positioned by a primary molding die 8, and a coil 3, whose coil heat dissipation surface region 3a is positioned by the primary molding die 8, by primary injection molding to form a primary molded product A; and a secondary molding step of integrating the primary molded product A, whose core heat dissipation surface regions 2a and coil heat dissipation surface regions 3a are positioned by a secondary molding die 9, and a plurality of mounting brackets 4, positioned by the secondary molding die 9, by secondary injection molding.

[0023] To explain in more detail, as shown in Figure 5, in the primary molding process, first, one core member 21 is set in the primary molding die 8 with its legs 21a to 21c extending upwards. Next, the coil 3 is set so as to be wound around the intermediate leg 21b of the set core member 21. After that, the other core member 21 is placed on top of the first core member 21 with its legs 21a to 21c extending downwards.

[0024] As shown in Figure 5, the primary molding die 8 includes a fixed portion 81 and a plurality of movable portions 82 to 85 that are movable relative to the fixed portion 81. The fixed portion 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 vertical direction, a second surface 81b that rises from one end of the first surface 81a and abuts against the core heat dissipation surface region 2a of the one core member 21 to position the one core member 21 in the horizontal 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 region 3a of the coil 3 to position the coil 3 in the horizontal direction, and a fifth surface (not shown) that abuts against the lower surface of the coil 3 to position the coil 3 in the vertical direction.

[0025] The movable parts 82-85 are slid in the direction of the arrows shown in Figure 5 after the two core members 21 and the coil 3 are set in the primary molding die 8, and then contact predetermined locations on the core member 21 or the coil 3 to position the core member 21 or the coil 3. Specifically, the first movable part 82 contacts 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 contacts the opposite side of 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 third movable part 84 contacts the opposite side of the core heat dissipation surface area 2a of one core member 21 to position one core member 21 in the left-right direction, and the fourth movable part 85 contacts the opposite side of the coil heat dissipation surface area 3a of the coil 3 to position the coil 3 in the left-right direction.

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

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

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

[0029] The secondary molding die 9 comprises a first surface 9a that abuts the coil heat dissipation surface area 3a of the primary molded product A, a second surface 9b that is parallel to the first surface 9a and abuts the core heat dissipation surface area 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 the lower surfaces of the plurality of 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 section 73 and the core cooling section 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 section 73 and the threaded section 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 precisely defined. Therefore, in the heat sink 7 to which the reactor 1 is assembled, the core heat dissipation surface area 2a and the coil heat dissipation surface area 3a can be positioned with high precision, improving the cooling efficiency of the reactor 1.

[0031] [Differentiation] Next, a modified example of the reactor 1 will be described with reference to Figure 10. However, for components common to the previously described embodiment, the same reference numerals as in the previously described embodiment may be used, and the description of the previously described embodiment may be referred to.

[0032] As shown in Figure 10(a), in the above-described embodiment, the core 2 is constructed by combining two core members 21, with all the legs 21a to 21c in close contact with each other. However, in order to adjust the impedance characteristics of the reactor 1, as shown in the first modified example in Figure 10(b), the intermediate 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 intermediate legs 21b.

[0033] Furthermore, as shown in Figure 10(a), the core member 21 of the embodiment described above has rounded corners at the tip corners of the leg portions 21a to 21c and the corner of the connecting portion 11d, which are cut out in an arc shape. However, as shown in the second modified example in Figure 10(c), the corners may be cut out in an inclined shape, or as shown in the third modified example in Figure 10(d), the corners may be right-angled without any cutouts. The corner shape of the core member 21 can be appropriately selected according to ease of manufacturing, the required distribution of leakage flux, and the optimization of inductance saturation characteristics.

[0034] Furthermore, as shown in the fourth modified example in Figure 10(e), the reactor 1 may also be fitted with a core member 21 having a subgap G2. Such a core member 21 is constructed, for example, by dividing the intermediate leg portion 21b and bonding the divided leg portion 21b via a gap spacer.

[0035] It should be noted that the present invention is not limited to the embodiments described above, and various modifications and changes are possible within the scope of the claims. For example, the number of mounting brackets 4 is not limited to 3, but may be 4 or more. Also, the multiple mounting brackets 4 may not be arranged on the same plane, but on different planes with steps. [Explanation of symbols]

[0036] 1 Reactor 2 cores 2a Core heat dissipation surface area 21 Core members 3 coils 3a Coil heat dissipation surface area 4 Mounting brackets 5 Primary molded resin part 6 Secondary molded resin part 7 Heatsink 8. Primary molding die 9. Secondary molding die A Primary molded product

Claims

1. A reactor that is integrally molded by injection molding, The core and The coil wound around the aforementioned core, Multiple mounting brackets that serve as mounting points for the reactor, A primary molded resin part formed by primary injection molding, It comprises a secondary molded resin part formed by secondary injection molding, The core is composed of multiple core members and has a core heat dissipation surface region that remains exposed even after the secondary injection molding. The coil is composed of an edgewise coil made by winding a flat wire at a right angle, and has a coil heat dissipation surface region that remains exposed even after the secondary injection molding. The primary molded resin portion is formed by integrating a plurality of core members whose core heat dissipation surface regions are positioned by a primary molding die, and the coil whose coil heat dissipation surface region is positioned by the primary molding die, thereby forming a primary molded product. The reactor is characterized in that the secondary molded resin portion integrates the primary molded product, in which the core heat dissipation surface region and the coil heat dissipation surface region are positioned by the secondary mold, and a plurality of mounting brackets positioned by the secondary mold.

2. The reactor according to claim 1, characterized in that the plurality of core members and the coil are integrated via the primary molded resin portion without the use of a bobbin and adhesive.

3. A method for manufacturing a reactor integrally molded by injection molding, The aforementioned reactor is, The core and The coil wound around the aforementioned core, The reactor comprises a plurality of mounting brackets that serve as mounting parts for the reactor, The core is composed of multiple core members, The aforementioned coil is composed of an edgewise coil made by winding a flat wire at a right angle, The method for manufacturing the reactor is as follows: A process of forming a primary molded product by integrating a plurality of core members, whose core heat dissipation surface regions are positioned by a primary molding die, and a coil, whose coil heat dissipation surface region is positioned by the primary molding die, by primary injection molding, A method for manufacturing a reactor, comprising the steps of: integrating a primary molded product, in which the core heat dissipation surface region and the coil heat dissipation surface region are positioned by a secondary molding die, and a plurality of mounting brackets positioned by the secondary molding die, by secondary injection molding.

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