JP7720363B2 - Filling device, filling method for composite magnetic material, and manufacturing method for metal composite core - Google Patents

Description

The present invention relates to a filling device for filling a composite magnetic material that constitutes a metal composite core formed by curing a resin, a filling method for the composite magnetic material, and a manufacturing method for a metal composite core.

Coil components are used in a variety of applications, including office equipment, solar power generation systems, and automobiles. One example of a coil component is a reactor. A reactor is an electromagnetic component that converts electrical energy into magnetic energy and stores and releases it.

Coil components primarily consist of a core, a coil, and a resin member. The coil is attached to the outer periphery of the core. The core serves as a magnetic path for the magnetic flux generated by the coil. A resin member is provided between the core and coil to insulate them from each other.

The core is made of a magnetic material, such as a dust core. A dust core is made by compacting magnetic powder to produce a powder compact, which is then annealed. The powder compact is compacted under high pressures of 10 to 20 ton/ ^cm² . Therefore, dust cores are limited to shapes that can withstand such high pressures. Therefore, metal composite cores made of a composite magnetic material that mixes magnetic powder with resin have attracted attention. Metal composite cores are made by hardening the resin of the composite magnetic material. Metal composite cores do not require compaction, or even if they do, the pressure is low, at around 15.7 kg/cm² or ^less , which increases the freedom of core shape.

Japanese Patent Application Laid-Open No. 2000-195737

If the resin content in the composite magnetic material is increased, for example to 10 wt% relative to the magnetic powder, the characteristics of the coil component will deteriorate. Therefore, it is desirable to keep the resin content in the range of 3 wt% to 5 wt% relative to the magnetic powder.

However, if the resin content is set between 3 wt% and 5 wt%, the viscosity of the composite magnetic material increases and its flowability deteriorates. As a result, the composite magnetic material cannot be filled into the case by machine and must be done by hand, resulting in poor productivity. Furthermore, because it is done by hand, the density of the metal composite core varies and is unstable.

The object of the present invention is to solve the above-mentioned problems by providing a filling device, a filling method for composite magnetic material, and a manufacturing method for metal composite cores that can increase the productivity of the filling work of composite magnetic material and suppress density variation in metal composite cores.

In order to solve the above-mentioned problems, the filling device of the present invention is a filling device that mixes resin and magnetic powder and fills the composite magnetic material that constitutes a metal composite core formed by hardening the resin. It includes an extruder that extrudes the composite magnetic material, a cylindrical case attached to the extruder and filled with the composite magnetic material extruded from the extruder, and a cover that closes the opening of the case. The extruder has a cylindrical portion into which the composite magnetic material is injected, and a pressing portion located inside the cylindrical portion and extruding the composite magnetic material toward the case. The outermost portion of the pressing portion is located near the inner surface of the cylindrical portion. The cover has holes. The resin that constitutes the composite magnetic material is contained in a range of 3 wt% to 5 wt% of the magnetic powder.

The composite magnetic material filling method of the present invention includes a composite magnetic material preparation step of mixing magnetic powder and resin to prepare a composite magnetic material, an injection step of injecting the composite magnetic material into a filling device, and a filling step of filling a cylindrical case with the composite magnetic material. The filling device has a cylindrical portion into which the composite magnetic material is injected and a pressing portion disposed inside the cylindrical portion and extruding the composite magnetic material toward the case. The case has an opening on the opposite side to the opening where the composite magnetic material is filled, which is closed with a cover, and the cover has a hole. In the composite magnetic material preparation step, the resin is added to the magnetic powder in a range of 3 wt% to 5 wt% to prepare a clay-like composite magnetic material. In the filling step, the outermost peripheral portion of the pressing portion is located near the inner peripheral surface of the cylindrical portion, and the pressing portion extrudes the composite magnetic material that has flowed into the cylindrical portion toward the case.

Furthermore, a method for manufacturing a metal composite core, which includes a curing step for curing the resin of the composite magnetic material filled by the above-mentioned filling method, is also an aspect of the present invention.

This invention increases the productivity of the composite magnetic material filling process and reduces density variations in metal composite cores.

1 is a schematic diagram showing a general configuration of a filling device according to an embodiment. 1 is a cross-sectional view showing a schematic configuration of an extruder according to an embodiment. FIG. FIG. 2 is a schematic diagram showing the configuration of an injection plate. FIG. 2 is a perspective view showing the overall configuration of the case. FIG. 2 is a perspective view showing a schematic overall configuration of a reactor. FIG. 4 is a schematic view of the cover as viewed from the central axis direction. FIG. 10A and 10B are schematic diagrams showing the shape of a case and the position of a cover in another embodiment. 10A and 10B are schematic diagrams showing the shape of a case and the position of a cover in another embodiment. 10A and 10B are schematic diagrams showing the shape of a case and the position of a cover in another embodiment. 10A and 10B are schematic diagrams showing the shape of a case and the position of a cover in another embodiment. 10A and 10B are schematic diagrams illustrating the configuration of a pressing portion in another embodiment.

(Embodiment)
The filling device of this embodiment will be described with reference to the drawings. Fig. 1 is a schematic diagram showing the general configuration of the filling device of this embodiment. Fig. 2 is a cross-sectional schematic diagram showing the general configuration of the extruder of this embodiment.

The filling device 1 is a device that fills a case 3 with a composite magnetic material that constitutes a metal composite core 5 (hereinafter referred to as an "MC core"; see Figures 5 and 7). The MC core 5 is a core formed by mixing a magnetic material with a resin to create a composite magnetic material, and then hardening the resin. The MC core 5 is a component of a coil part such as a reactor 8 (see Figure 5). The composite magnetic material is a highly viscous, clay-like material in which resin is added in the range of 3 wt% to 5 wt% of the magnetic powder. The filling device 1 includes an extruder 2, a case 3, and a cover 4.

The extruder 2 extrudes the composite magnetic material and fills it into the case 3. As shown in Figure 2, the extruder 2 has an injection port 21, a cylindrical portion 22, a pressing portion 23, and an injection plate 24.

The composite magnetic material is injected into the injection port 21. The injection port 21 is a cylindrical member. The injection port 21 is positioned so that the cylindrical axis of the injection port 21 is perpendicular to the central axis C of the cylindrical portion 22. The injection port 21 is positioned on the bottom surface 221 side of the cylindrical portion 22. The injection port 21 is connected to the cylindrical portion 22. The inner diameter of the injection port 21 is smallest at the point where it communicates with the cylindrical portion 22 and increases toward the top. In other words, the inner surface of the injection port 21 has an inclined shape. The up-down direction here refers to the direction perpendicular to the installation surface on which the filling device 1 is installed. The injection port 21 may also be provided with a storage section for storing the injected composite magnetic material.

The cylindrical portion 22 is a bottomed cylindrical member in which only one end face perpendicular to the central axis C is open. That is, the cylindrical portion 22 has a bottom surface 221. The composite magnetic material injected from the injection port 21 flows into the cylindrical portion 22. The cylindrical portion 22 has an overhanging portion 222. The overhanging portion 222 is rectangular. The overhanging portion 222 is provided at the tip of the cylindrical portion 22. The overhanging portion 222 is larger than the outer diameter of the cylindrical portion 22. The overhanging portion 222 has an opening of the same shape as the cylindrical portion 22, and this opening overlaps with the opening of the cylindrical portion 22.

The pressing portion 23 presses the composite magnetic material that has flowed into the cylindrical portion 22. As shown in FIG. 2, the pressing portion 23 is provided inside the cylindrical portion 22. The pressing portion 23 has a shaft portion 231 and a rotating blade 232. The shaft portion 231 is provided rotatably. A motor or the like can be used as a driving source for the shaft portion 231. The shaft portion 231 penetrates the bottom surface 221 of the cylindrical portion 22 and extends along the central axis of the cylindrical portion 22. The shaft portion 231 extends to the vicinity of the protruding portion 222 of the cylindrical portion 22.

The rotating blades 232 are spiral-shaped and are provided around the shaft portion 231. More specifically, the rotating blades 232 move along the central axis C while rotating around the shaft portion 231. The rotating blades 232 rotate in conjunction with the rotation of the shaft portion 231. The outermost periphery of the rotating blades 232 is located near the inner surface of the cylindrical portion 22. "Near" here means that there is no gap so that the rotating blades 232 can rotate; as long as they can rotate, the rotating blades 232 and the inner surface of the cylindrical portion 22 may be in contact with each other without any gaps.

The injection plate 24 is a thin plate-shaped member. The injection plate 24 is fixed to the protruding portion 222 with bolts or the like. In other words, the injection plate 24 is detachable from the protruding portion 222. The injection plate 24 covers the opening of the cylindrical portion 22.

Figure 3 is a schematic diagram showing the configuration of the injection plate 24. The injection plate 24 has an injection area 241 that is approximately the same size as the opening of the protrusion 222. The injection plate 24 has multiple holes 242 within the injection area 241. The holes 242 are circular. The holes 242 are through-holes that penetrate the injection plate 24. The composite magnetic material is injected from these holes 242 to the outside of the extruder 2. In other words, the holes 242 serve as injection ports. The holes 242 are positioned on a projected area in the direction of the central axis C of the center leg covering portion 31 of the case 3, which will be described later. Note that the shape of the holes 242 does not have to be circular, and may be rectangular, triangular, or other shapes.

Figure 4 is a perspective view showing the overall configuration of the case 3. The case 3 is a component filled with a composite magnetic material. The case 3 is cylindrical with open ends. The case 3 is positioned so that the openings are perpendicular to the central axis C.

The case 3 is positioned between the injection plate 24 and the cover 4. While the case 3 is sandwiched between the injection plate 24 and the cover 4, the tip of the fixing device 41 erected on the injection plate 24 passes through a hole formed in the cover 4, and the penetrating tip is fastened with a nut or the like, thereby fixing the case 3 in place. The case 3 has a center leg covering portion 31, four outer leg covering portions 32, and an integral connecting covering portion 33.

When attached to the extruder 2, the center leg covering portion 31 and the outer leg covering portion 32 extend along the central axis C. The center leg covering portion 31 and the outer leg covering portion 32 are approximately the same length. The center leg covering portion 31 is cylindrical. The center leg covering portion 31 is circular. The hole 242 of the injection plate 24 is located on the projection area of the center leg covering portion 31 in the direction of the central axis C. The center leg covering portion 31 has a larger cross-sectional area of the internal space than the outer leg covering portion 32. The cross-sectional area of the internal space refers to the area perpendicular to the central axis C.

The outer leg covering portion 32 is roughly triangular in shape. The outer leg covering portion 32 is cylindrical in shape. The four outer leg covering portions 32 are arranged at equal intervals in the circumferential direction around the center leg covering portion 31. In other words, the outer leg covering portions 32 are arranged at 90-degree intervals.

A pair of connecting covering parts 33 are positioned to sandwich the middle leg covering part 31 and the outer leg covering part 32. The connecting covering part 33 connects the middle leg covering part 31 and the four outer leg covering parts 32. The connecting covering part 33 has an opening of the same shape as the openings of the middle leg covering part 31 and the outer leg covering part 32, and is connected to the internal spaces of the middle leg covering part 31 and the outer leg covering part 32. The case 3 is divided into two parts so that the coil 6 (described below) can be attached to the middle leg covering part 31.

The case 3 is made of resin. Examples of resins that can be used to make up the case 3 include epoxy resin, unsaturated polyester resin, urethane resin, BMC (Bulk Molding Compound), PPS (Polyphenylene Sulfide), and PBT (Polybutylene Terephthalate).

The case 3 is one of the components of the reactor 8. Figure 5 is a perspective view showing the overall configuration of the reactor. The coil 6 is attached to the center leg sheath 31 of the case 3. Meanwhile, the MC core 5, made of hardened composite magnetic resin, is formed in the internal space of the case 3. The case 3 serves to insulate the MC core 5 from the coil 6. Note that the case 3 does not necessarily have to be a component of the reactor 8.

The coil 6 is composed of a single conductive member coated with an insulating material such as enamel. The coil 6 is formed by winding the conductive member into a cylindrical shape while shifting the winding position in the direction of the winding axis. The conductive member is, for example, a rectangular wire. The coil 6 is an edgewise coil in which the wide surface of the rectangular wire extends in a direction perpendicular to the winding axis of the coil 6. However, the coil 6 may also be a flatwise coil. A round wire may also be used as the conductive member.

The coil 6 is attached to the leg covering part, which has a large cross-sectional area of the internal space. In this embodiment, the coil 6 is attached to the middle leg covering part 31. A lead wire is drawn out from the coil 6. The lead wire is connected to the bus bar 7. By connecting the lead wire to the bus bar 7, power is supplied to the coil from the external device.

As shown in Figure 1, the cover 4 covers the opening of the case 3 on the side opposite the extruder 2. In other words, the case 3 is sandwiched between the cover 4 and the extruder 2. The cover 4 has a rectangular thin plate shape. The cover 4 is fixed to the injection plate 24 with fasteners 41 such as bolts.

Figure 6 is a schematic diagram of the cover 4 viewed from the central axis direction. The cover 4 has hole regions 42. The hole regions 42 are located outside the projection region R of the legs of the MC core 5, which has a large cross-sectional area of the internal space. In this embodiment, the hole regions 42 are located outside the projection region R of the center leg covering portion 31. The four hole regions 42 are preferably located at positions farthest from the holes 242 of the injection plate 24. In other words, the hole regions 42 are preferably located at positions farthest from the projection region R of the center leg covering portion 31. Four hole regions 42 are provided. The four hole regions 42 are located at the vertices of the rectangular cover 4 that are farthest from the projection region R of the center leg covering portion 31, corresponding to the positions of the outer leg covering portions 32.

The cover 4 has holes 43. The holes 43 are through-holes that penetrate the cover 4. The holes 43 are formed within the hole region 42. Multiple holes 43 are formed in one hole region 42. The holes 43 are circular. The area of one hole 43 is smaller than the cross-sectional area of the internal space of the outer leg covering portion 32.

Next, we will explain the composite magnetic material and MC core 5. The composite magnetic material is composed of magnetic powder and resin. Soft magnetic powder can be used as the magnetic powder, and in particular, Fe powder, Fe-Si alloy powder, Fe-Al alloy powder, Fe-Si-Al alloy powder (Sendust), amorphous alloy powder, nanocrystal, or a mixture of two or more of these powders can be used. Examples of Fe-Si alloy powder that can be used include Fe-6.5% Si alloy powder and Fe-3.5% Si alloy powder.

The magnetic powder may be magnetic powders with different average particle sizes. In other words, the magnetic powder may be composed of a first powder and a second powder with a smaller average particle size than the first powder. In this specification, average particle size refers to D50 (median diameter) unless otherwise specified. Furthermore, the first powder and second powder may be the same or different types.

The average particle size of the first powder is preferably 100 μm or more and 200 μm or less, and that of the second powder is preferably 3 μm or more and 10 μm or less. By setting the sizes within these ranges, the second powder, which has a smaller average particle size, can fill the gaps between the first powder particles, improving density and magnetic permeability and reducing iron loss.

The resin is mixed with the magnetic powder to hold it in place. The resin can be a thermosetting resin, a UV-curable resin, or a thermoplastic resin. Examples of thermosetting resins that can be used include phenolic resin, epoxy resin, unsaturated polyester resin, polyurethane, diallyl phthalate resin, and silicone resin. Examples of UV-curable resins that can be used include urethane acrylate, epoxy acrylate, acrylate, and epoxy resins. It is preferable to use a resin with excellent heat resistance, such as polyimide or fluororesin, as a thermoplastic resin.

The resin content is set to a range of 3 wt% to 5 wt% relative to the magnetic powder. If the resin content is less than 3 wt%, the composite magnetic material will have a dry, powdery texture and poor fluidity, making it difficult to fill the case 3 using the extruder 2. Furthermore, the bonding strength of the magnetic powder will be insufficient, reducing the mechanical strength of the MC core. On the other hand, if the resin content is greater than 5 wt%, the viscosity will decrease, and the resin contained in the composite magnetic material may leak from the case 3. Furthermore, the density of the MC core will decrease, and the magnetic permeability will decrease, as the magnetic powder will no longer be able to be held tightly. If the resin content is set to 3 wt% to 5 wt%, the viscosity of the composite magnetic material will increase, reaching a range that would previously have required manual filling. However, the filling device 1 of this embodiment makes it possible to fill the case 3 using the extruder 2.

The MC core 5 is made of hardened composite magnetic resin. The MC core 5 is used as the magnetic body of the reactor 8. Figure 7 is an exploded perspective view of the reactor 8. For ease of explanation, the coil 6 is not shown in Figure 7. The MC core 5 has a shape similar to that of the case 3.

The MC core 5 has a center leg portion 51, an outer leg portion 52, and a connecting portion 53. The coil 6 is attached to the center leg portion 51. The center leg portion 51 is covered by the center leg covering portion 31. In other words, the center leg covering portion 31 insulates the center leg portion 51 from the coil 6. The center leg portion 51 is circular.

The outer legs 52 are arranged around the middle leg 51. There are four outer legs 52. The four outer legs 52 are arranged at equal intervals of 90 degrees around the middle leg 51, with the middle leg 51 at the center. The outer legs 52 are roughly triangular in shape. A pair of connecting portions 53 are provided. The pair of connecting portions 53 sandwich the middle leg 51 and the outer legs 52. They connect the middle leg 51 and the four outer legs 52. The middle leg 51, outer legs 52, and connecting portion 53 are formed as a single, seamless piece.

(Manufacturing method)
Next, a description will be given of a method for filling the composite magnetic material and a method for manufacturing the MC core 5. The method for filling the composite magnetic material of this embodiment includes a composite magnetic material preparation step, an attachment step, an injection step, and a filling step. Furthermore, the method for manufacturing the MC core 5 further includes a curing step in addition to the steps of the method for filling the composite magnetic material.

The composite magnetic material production process involves adding 3 wt% to 5 wt% of resin to magnetic powder and mixing the magnetic powder and resin. Mixing of the magnetic powder and resin is performed automatically or manually using any mixer. The mixing time can be set as appropriate, but is, for example, 10 minutes. A composite magnetic material is produced through the composite magnetic material production process.

The mounting process is a process of mounting the case 3 and cover 4 to the extruder 2. The connecting cover portion 33 of the case 3 is placed opposite the injection plate 24 of the extruder 2, and the connecting cover portion 33 and injection plate 24 are abutted. At this time, the case 3 is fixed so that the hole 242 of the injection plate 24 is positioned on the projected area of the center leg cover portion 31 of the case 3. Then, each hole area 42 of the cover 4 covers the opening of the case 3 so that it corresponds to the position of each outer leg cover portion 32 of the case 3. In this state, the cover 4 is fixed to the injection plate 24 with fasteners 41 such as bolts. In this embodiment, the coil 6 is wound around the case 3 prior to the mounting process, and the case 3 with the coil 6 is attached to the extruder 2.

It is noted that either the composite magnetic material production process or the attachment process may be performed first. That is, the attachment process may be performed first, followed by the composite magnetic material production process. The composite magnetic material production process and the attachment process may also be performed simultaneously in parallel.

The injection process is a process in which the composite magnetic material produced in the composite magnetic material process is injected into the extruder 2. In the injection process, the composite magnetic material is injected into the injection port 21 of the extruder 2.

The filling process is a process in which the extruder 2 fills the case 3 with the composite magnetic material. The composite magnetic material injected in the injection process flows into the cylindrical portion 22 through the injection port 21. When the motor is driven in this state, the shaft portion 231 of the pressing portion 23 rotates. As the shaft portion 231 rotates, the rotating blades 232 also rotate, and the composite magnetic material in the cylindrical portion 22 is carried toward the injection plate 24. The pressing force in the filling process can be adjusted as appropriate depending on the viscosity of the composite magnetic material, but it is preferably at least 5 MPa or more.

The outermost periphery of the rotating blade 232 does not have a gap with the inner periphery of the cylindrical portion 22. Therefore, the composite magnetic material is transported to the injection plate 24 side without remaining in the cylindrical portion 22. The composite magnetic material transported to the injection plate 24 side is pushed out through the hole 242 in the injection plate 24 and flows into the case 3.

Because the hole 242 is located on the projected area of the center leg covering portion 31 of the case 3, the composite magnetic material flows into the internal space of the center leg covering portion 31. The composite magnetic material that flows into the internal space of the center leg covering portion 31 reaches the connecting covering portion 33. The connecting covering portion 33 is covered by the cover 4, and the hole area 42 of the cover 4 is located outside the projected area R of the center leg covering portion 31 around which the coil 6 is wound. Therefore, the composite magnetic material that reaches the connecting covering portion 33 hits the cover 4 in a portion where the hole 43 is not formed and spreads into the internal space of the connecting covering portion 33. At this point, the composite magnetic material is not extruded through the hole 43.

The composite magnetic material that reaches the connecting sheath 33 gradually fills the internal space of the connecting sheath 33. Because the area of one hole 43 in the cover 43 is smaller than the cross-sectional area of the internal space of the outer leg sheath 32, the composite magnetic material that fills the internal space of the connecting sheath 33 easily flows into the internal space of the outer leg sheath 32. Therefore, even at this point, the composite magnetic material is difficult to extrude from the hole 43 in the cover 43, and begins to flow into the internal space of the outer leg sheath 32. The composite magnetic material that has flowed into the internal space of the outer leg sheath 32 is extruded toward the extruder 2, reaches the connecting sheath 33 on the extruder 2 side, and fills the space in that connecting sheath 33.

When all the spaces in the center leg covering section 31, the four outer leg covering sections 32, and the pair of connecting covering sections 33 are filled with the composite magnetic material, the composite magnetic material is extruded through the hole 43 in the cover 4. This signals the motor to stop driving, stopping the rotation of the shaft section 231 and the rotating blades 232, and completing the filling process.

The curing process is a process of curing the resin of the composite magnetic material filled in the case 3. First, the case 3 is removed from the extruder 2. Then, the process moves to the resin curing process. When curing the resin by drying, the drying atmosphere can be air. The drying time can be changed as appropriate depending on the type of resin, content, drying temperature, etc., and can be, for example, 1 to 4 hours, but is not limited to this. The drying temperature can be changed as appropriate depending on the type of resin, content, drying time, etc., and can be, for example, 85°C to 150°C, but is not limited to this. The drying temperature is the temperature of the drying atmosphere.

In addition, resin hardening is not limited to drying; the hardening method varies depending on the type of resin. For example, if the resin is a thermosetting resin, it is hardened by applying heat, and if the resin is a UV-curable resin, it is hardened by irradiating the molded body with UV light.

In the curing process, the process of curing the resin may be repeated multiple times. Furthermore, for example, if the resin is cured by drying, the drying temperature or drying time may be changed each time the process is repeated. The MC core 5 is produced through the curing process.

(effect)
As described above, the filling device of this embodiment includes the extruder 2 that extrudes the composite magnetic material, the cylindrical case 3 that is attached to the extruder 2 and filled with the composite magnetic material extruded from the extruder 2, and the cover 4 that closes the opening of the case 3. The extruder 2 has a cylindrical portion 22 into which the composite magnetic material is injected, and a pressing portion 23 that is provided inside the cylindrical portion 22 and extrudes the composite magnetic material toward the case 3. The outermost portion of the pressing portion 23 is located near the inner peripheral surface of the cylindrical portion 22, and the cover 4 has holes 43. The resin that constitutes the composite magnetic material is contained in a range of 3 wt % to 5 wt % with respect to the magnetic powder.

This makes it possible to fill the case 3 with even highly viscous composite magnetic materials using the filling device 1, thereby increasing the productivity of the filling process. Furthermore, because filling is done by machine, density variations in the MC core 5 can be reduced compared to manual filling, resulting in stable coil component characteristics.

The case 3 also serves as an insulating member that insulates the MC core 5 from the coil 6, making it a component of the reactor 8. This eliminates the need for a process to coat the MC core 5 with an insulating member after manufacturing the MC core 5, improving productivity.

Furthermore, the cover 4 has a hole 43. The composite magnetic material extruded by the extruder 2 is injected at a higher pressure than when done manually. Therefore, if the cover 4 did not have a hole 43, the internal pressure inside the case 3 would increase, which could result in damage to the case 3. However, by providing a hole 43 in the cover 4, as in this embodiment, the internal pressure inside the case 3 can be prevented from increasing, preventing damage to the case 3.

The case 3 has a center leg covering portion 31 and an outer leg covering portion 32 extending along the central axis direction of the cylindrical portion 22, and the cross-sectional area of the internal space of the center leg covering portion 31 is larger than the cross-sectional area of the outer leg covering portion 32. The extruder 2 has a hole 242 which is an injection port for injecting the composite magnetic material toward the center leg covering portion 31, and the holes 43 in the cover 4 are provided in hole areas 42 at the four corners of the cover 4, which are outside the projection area R in the central axis direction of the center leg covering portion 31.

In this way, the hole 43 in the cover 4 is formed at a position away from the injection port. Therefore, the area of the space inside the case 3 near the hole 43 is the last to be filled with the composite magnetic material. Therefore, when the composite magnetic material is pushed out from the hole 43, it signals that every corner of the case 3 has been filled with the composite magnetic material, improving the efficiency of the filling process.

Furthermore, multiple holes 242 are formed in one hole region 42. If a single large hole were formed in one hole region 42, there is a risk that the composite magnetic material would be pushed out of the hole before it was filled to every corner of the case 3. However, by creating multiple holes 43 in one hole region 42 with the same hole area as a single large hole, the composite magnetic material is prevented from being pushed out of the hole 43 before it is filled to every corner of the case 3. Furthermore, by creating multiple holes 242, the injection pressure can be increased compared to when a single large hole of the same area is used. As a result, the composite magnetic material can be filled to every corner of the case 3.

(Example)
The present invention will be described in more detail based on examples. However, the present invention is not limited to the following examples. MC cores of Example 1 and Comparative Examples 1 and 2 were produced. The MC cores of Example 1 and Comparative Examples 1 and 2 were produced using the same materials, under the same conditions, and by the same method, except for the filling method of the composite magnetic material.

First, a composite magnetic material was prepared. Two types of magnetic powder with different average particle sizes were used. Fe-6.5Si alloy powder was used for both the first and second powders. The average particle size of the first powder was 150 μm, and the average particle size of the second powder was 8 μm. The content ratio of the first powder to the second powder was 70:30. Epoxy resin was used as the resin. 3.75 wt% of the resin was added to the soft magnetic powder. After mixing the first powder and the second powder, resin was further mixed to obtain the composite magnetic material.

Next, the composite magnetic material was filled into case 3. The shape of case 3 was the same as that described in the above embodiment. In the example, case 3 was attached to extruder 2, and the composite magnetic material was filled into case 3 using filling device 1. On the other hand, in comparative example 1, the filling was done manually by an operator without using a machine such as filling device 1. In comparative example 2, the operator filled the case manually and then pressurized. The pressure was 5 kgf.

After filling the case with the composite magnetic material, the resin of the composite magnetic material was cured. The curing conditions were a temperature of 150°C for 3 hours. Using these steps, 10 MC cores each for the example and comparative examples 1 and 2 were produced.

The density of each MC core was measured. Density is the apparent specific gravity/volume, and measurement samples cut from each MC core were measured using the Archimedes method. Specifically, the measurements were carried out as follows:

(1) The sample is dried in a thermostatic chamber at 110°C, and the mass (dry weight) is measured after cooling to room temperature.
(2) After measuring the dry weight, the sample is submerged in water until saturated, and the mass (underwater weight) is measured while it is suspended in water by a wire (excluding the mass of the jig such as the wire).
(3) The apparent specific gravity is calculated using the following formula (1).
(Equation 1)
Apparent specific gravity = dry weight / (dry weight - weight in water) (1)
(4) Calculate the density from the apparent specific gravity and the volume of the sample.

The results are shown in Table 1 below.

As shown in Table 1 above, the average density of the Example was 5.85 (g/cm ³ ), which is a higher value than the average densities of Comparative Examples 1 and 2. In addition, the CV value of the Example was 0.0120, which is a lower value than the CV values of Comparative Examples 1 and 2. Therefore, it was confirmed that filling the composite magnetic material using the filling device 1 results in a higher density and reduces density variation, compared to filling by hand.

Furthermore, a reactor was fabricated using this MC core 5, and iron loss was measured. The iron loss measurement conditions involved winding 33 turns of coil 6 around the center leg 51 (center leg sheath 31 of the case) of each MC core. A 5 kHz sinusoidal current was passed through coil 6, and reactor loss (W) was measured using a power meter (Yokogawa Electric Corporation: WT3000E) at current values where the magnetic flux density was 10 mT and 80 mT. The coil loss, calculated from the coil's DC resistance and current value, was then subtracted from the measured reactor loss result, and the result was taken as iron loss.

The results are shown in Table 2 below.

As shown in Table 2 above, when the maximum magnetic flux density Bm is either 10 mT or 80 mT, the loss in the example is reduced to less than half of that in comparative example 1 and approximately 60% of that in comparative example 2. Therefore, it was confirmed that filling the composite magnetic material using filling device 1 significantly reduces the iron loss of the reactor.

(Other embodiments)
Although the present specification describes an embodiment of the present invention, this embodiment is presented as an example and is not intended to limit the scope of the invention. The above-described embodiment can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the scope of the invention. The embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as set forth in the claims.

In the above embodiment, the case 3 has a center leg covering portion 31 and four outer leg covering portions 32, but the shape of the case 3 is not limited to this. As shown in Figure 8, there may be two outer leg covering portions 32. In this case, the two outer leg covering portions 32 are arranged so that the center leg covering portion 31, on which the coil 6 is attached, is sandwiched between them. The hole areas 42 of the cover 4 are provided at the four corners of the cover 4 that are outside the projection area R of the center leg covering portion 31.

Also, as shown in Figure 9, the inner surfaces of the two outer leg covering portions 32 that face the coil 6 may be shaped to match the shape of the coil 6. Even in this case, the hole areas 42 of the cover 4 are provided at the four corners of the cover 4 that are outside the projection area R of the middle leg covering portion 31.

Furthermore, the case 3 may not have a center leg covering portion 31 and may be composed of only two outer leg covering portions 32, as shown in Figure 10. A coil 6 is attached to each of the outer leg covering portions 32. In this case, the hole area 42 of the cover 4 is located outside the projected area R of the outer leg covering portion 32 to which the coil 6 is attached. More specifically, it is preferable to provide two hole areas 42, one above and one below the center portion between the outer leg covering portions 32. In this case, the emission areas 241 of the emission plate 24 are each provided in the projected area R of the outer leg covering portion 32 to which the coil 2 is attached.

Also, as shown in Figure 11, a coil 6 may be attached to only one of the two outer leg covering portions 32. In this case, as in the case where a coil 6 is attached to each of the two outer leg covering portions 32, it is recommended that two coils be attached, one above the other in the central portion between the outer leg covering portions 32.

In the above embodiment, the pressing unit 23 is composed of the shaft 231 and the rotor blades 232, but the configuration of the pressing unit 23 is not limited to this. The pressing unit 23 may have a piston structure. For example, as shown in FIG. 12 , the pressing unit 23 has a shaft 233 and a push-out unit 234. The shaft 233 penetrates the bottom surface 221 of the cylindrical unit 22 and extends along the central axis C. The shaft 233 is movable along the central axis C. The push-out unit 234 is attached to the tip of the shaft 233 and moves in conjunction with the shaft 233. The outermost periphery of the push-out unit 234 is located near the inner circumferential surface of the cylindrical unit 22. By configuring the pressing unit 23 in this manner and moving the pressing unit 23 along the central axis, the composite magnetic material that has flowed into the cylindrical unit 22 can be pushed out through the hole 242 in the injection plate 24.

1 Filling device 2 Extruder 21 Inlet 22 Cylindrical portion 221 Bottom surface 222 Projection portion 23 Pressing portion 231 Shaft portion 232 Rotating blade 233 Shaft portion 234 Pushing portion 24 Injection plate 241 Injection area 242 Hole 3 Case 31 Center leg covering portion 32 Outer leg covering portion 33 Connecting covering portion 4 Cover 41 Fixing device 42 Hole area 43 Hole 5 Metal composite core (MC core)
51 Center leg portion 52 Outer leg portion 53 Connection portion 6 Coil 7 Bus bar 8 Reactor C Central axis

Claims (7)

A filling device that fills a composite magnetic material that constitutes a metal composite core formed by mixing a resin and a magnetic powder and hardening the resin,
an extruder that extrudes the composite magnetic material;
a cylindrical case attached to the extruder and filled with the composite magnetic material extruded from the extruder;
a cover that closes the opening of the case;
Equipped with
The extruder
a cylindrical portion into which the composite magnetic material is injected;
a pressing portion provided inside the cylindrical portion and configured to push the composite magnetic material toward the case;
and
an outermost peripheral portion of the pressing portion is located near an inner peripheral surface of the cylindrical portion;
the cover has a hole;
The resin constituting the composite magnetic material is contained in an amount of 3 wt % or more and 5 wt % or less with respect to the magnetic powder;
A filling device characterized by: the case has a plurality of leg covering portions extending along the central axis direction of the cylindrical portion,
At least one of the plurality of leg covering portions has an internal space with a cross-sectional area larger than that of the other leg covering portions,
the extruder has an injection port that injects the composite magnetic material toward the leg covering portion having the large cross-sectional area,
the hole is provided in a hole region that is outside a projected region in the central axis direction of the leg covering portion having the large cross-sectional area;
2. The filling device according to claim 1, wherein: a plurality of the holes are formed in the hole region;
3. The filling device according to claim 2, wherein: a composite magnetic material preparation step of mixing magnetic powder and resin to prepare a composite magnetic material;
an injection step of injecting the composite magnetic material into a filling device;
a filling step of filling the composite magnetic material into a cylindrical case;
Including,
The filling device is
a cylindrical portion into which the composite magnetic material is injected;
a pressing portion provided inside the cylindrical portion and configured to push the composite magnetic material toward the case;
and
an opening of the case opposite to the opening where the composite magnetic material is filled is closed with a cover;
the cover has a hole;
In the composite magnetic material preparation step, the resin is added to the magnetic powder in an amount of 3 wt % or more and 5 wt % or less to prepare a clay-like composite magnetic material;
in the filling step, an outermost portion of the pressing portion is located near an inner peripheral surface of the cylindrical portion, and the pressing portion pushes out the composite magnetic material that has flowed into the cylindrical portion toward the case;
A method for filling a composite magnetic material, characterized by: the case has a plurality of leg covering portions extending along the central axis direction of the cylindrical portion,
At least one of the plurality of leg covering portions has an internal space with a cross-sectional area larger than that of the other leg covering portions,
the hole is provided in a hole region that is outside a projected region in the central axis direction of the leg covering portion having the large cross-sectional area,
In the filling step, the pressing portion pushes the composite magnetic material into the case toward the leg covering portion having the larger cross-sectional area.
5. The method for filling a composite magnetic material according to claim 4, a plurality of the holes are formed in the hole region;
6. The method for filling a composite magnetic material according to claim 5, The method according to any one of claims 4 to 6 further includes a curing step of curing the resin of the composite magnetic material filled in the case.
A method for manufacturing a metal composite core, characterized by: