JP2023024143A - Coil device - Google Patents

Abstract

To obtain a coil device capable of coping with the enlargement of a core and effectively enhancing magnetic characteristics.SOLUTION: A coil device 10 includes a cylindrical coil 20, a columnar inner core 52 arranged inside the coil 20, and an outer core 54 arranged outside the coil 20, and the inner core 52 is made of a powder compact, and the outer core 54 has an outer core 60 arranged along the outer circumference of the coil. At least the outer core 60 is made by mixing and hardening magnetic powder and liquid resin.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to coil devices.

2. Description of the Related Art Conventionally, a core of a coil device that constitutes an inductor or the like is often formed by compacting a mixed powder containing metal-based magnetic powder or ferrite-based magnetic powder as a main component. A core composed of such a compacted body is formed by pressing a mixed powder with a press and then heat-treating or sintering it at a predetermined temperature.

By the way, in a coil device that can handle a large current, a large core is required as the size of the coil increases. However, when the core is formed by compacting, if the pressurizing capacity of the press is insufficient for the size of the core, the required mechanical strength cannot be ensured. Therefore, there is a problem that the pressurizing ability of the press hinders the enlargement of the core.

Therefore, a core made of a magnetic resin is being studied in order to meet the demand for a larger size while ensuring the mechanical strength of the core. The core made of a magnetic resin can be formed into a desired shape and size while ensuring mechanical strength because the magnetic powder such as metal powder and liquid resin are mixed and hardened.

For example, Patent Literature 1 discloses a coil device that includes a magnetic core that is arranged inside and outside a coil to form a closed magnetic circuit, and the magnetic core is made of a composite material containing soft magnetic powder and resin. . In this coil device, a coil is placed in a molding die for resin injection, and a molten mixture containing soft magnetic powder and raw resin is injected to integrally mold the coil and the magnetic core.

JP 2016-96227 A

However, the core made of a magnetic resin as in Patent Document 1 tends to have a lower magnetic permeability and a higher core loss than a core made of a powder compact. Therefore, in the coil device described in Patent Literature 1, there is a problem that it is difficult to improve the magnetic properties of the coil device as compared with the coil device provided with the core made of the compacted body.

The present disclosure has been made to solve the above problems, and an object of the present disclosure is to obtain a coil device that can cope with an increase in the size of a core and can effectively improve magnetic characteristics.

A coil device according to a first aspect of the present disclosure includes a cylindrical coil, a columnar inner core arranged inside the coil, and an outer core arranged outside the coil, and the inner The core is composed of a powder compact, the outer core has an outer core disposed along the outer periphery of the coil, and at least the outer core is formed by mixing magnetic powder and liquid resin and hardening them. It is made of magnetic resin.

In the coil device according to the present disclosure, a magnetic circuit is configured by a columnar inner core arranged inside the tubular coil and an outer core arranged outside the tubular coil. By the way, the inner core arranged inside the coil has a smaller diameter than the outer core. Easy to secure. On the other hand, the outer coil arranged outside the coil has a larger core than the inner core. In particular, the portion of the outer core that is arranged along the outer periphery of the coil has a large diameter, and it is difficult to ensure the desired pressurization capability when the outer core is formed of a powder compact. There are cases.

In the present disclosure, in the outer core, at least the outer core arranged along the outer circumference of the coil is made of magnetic resin. Since the magnetic resin is formed by mixing magnetic powder and liquid resin and hardening them, it is possible to form a desired size while ensuring mechanical strength. This makes it possible to cope with an increase in the size of the core.

In addition, the magnetic properties of the coil device are effectively enhanced by forming the inner core from a compacted body. That is, since it is difficult to increase the volume of the inner core arranged inside the coil due to restrictions on the arrangement space, the magnetic permeability and core loss of the inner core greatly affect the magnetic characteristics of the coil device. . Therefore, the inner core is made of a powder product, and the core material, which is the main part in terms of magnetic properties in the coil device, is made of a material with high magnetic permeability and low core loss. As a result, it is possible to optimize the arrangement of the cores made of the powder compacts, cope with the increase in size of the cores, and effectively improve the magnetic characteristics of the coil device.

1 is a perspective view of a coil device according to an embodiment of the present disclosure; FIG. FIG. 2 is a cross-sectional view of the coil device taken along line II-II of FIG. 1; It is an exploded perspective view of a coil device concerning an embodiment. It is a top view of a coil case concerning an embodiment. (A)-(C) are cross-sectional views of coil devices corresponding to Examples A-C of the present disclosure. 4A to 4C are cross-sectional views of coil devices corresponding to Examples D to F of the present disclosure; (A) to (I) are cross-sectional views of a coil device showing other embodiments of the present disclosure. (A) to (C) are cross-sectional views of coil devices corresponding to Comparative Examples A to C. FIG. 4 is a graph showing magnetic permeability of coil devices corresponding to Examples A to C; 4 is a graph showing core loss of coil devices corresponding to Examples A to C; 5 is a graph showing μH characteristics of Example A; 4 is a graph showing the Pcv-Bm characteristics of Example A. FIG. 4 is a graph showing the magnetic properties of Example A and Examples D to F. FIG.

A coil device 10 according to this embodiment of the present invention will be described below with reference to FIGS. In the present embodiment, for convenience of explanation, the directions indicated by up-down, left-right, and front-rear arrows shown in each drawing are defined as the up-down direction, left-right direction, and front-rear direction, respectively. Also, in each drawing, some reference numerals may be omitted in order to make the drawings easier to see.

As shown in FIGS. 1 to 4, the coil device 10 of this embodiment constitutes a choke coil as an example. The coil device 10 includes a tubular coil 20, a coil case 30 that houses the coil 20, and a core 50 that forms a magnetic circuit.

The coil 20 is made of a long conductive plate (for example, a copper plate). The coil 20 has a cylindrical winding portion 22 formed by spirally winding a plate material, and a pair of lead terminal portions 24A and 24B drawn out from the winding start and winding end of the winding portion 22. . The pair of lead-out terminal portions 24A and 24B has a plate-like shape with the plate thickness direction extending in the vertical direction, and extends radially outward from both axial ends of the wound portion 22 in parallel with each other. When the coil 20 is accommodated in the coil case, the cylindrical winding portion 22 is accommodated inside the coil case 30, and the pair of lead terminal portions 24A and 24B are drawn outside the coil case 30. As shown in FIG.

The coil case 30 is a box made of an insulating material (for example, resin). The coil case 30 includes a tubular portion 32 arranged inside the coil 20 (winding portion 22), a first side wall portion 34 arranged radially outside the tubular portion 32, and the first side wall portion 34. and a second side wall portion 36 disposed radially outwardly of.

The tubular portion 32 is formed in a cylindrical shape with an axial direction extending in the vertical direction, and the winding portion 22 of the coil 20 is arranged along the outer peripheral surface of the tubular portion 32 . When the core 50 is attached to the coil case 30 , the columnar inner core 52 is arranged inside the cylindrical portion 32 . A brim-shaped bottom wall portion 38 extending radially outward from the outer peripheral surface of the tubular portion 32 is provided at the lower end portion of the tubular portion 32 .

The first side wall portion 34 is formed in a cylindrical shape having a diameter larger than that of the cylindrical portion 32 , and stands upward from the bottom wall portion 38 on the radially outer side of the cylindrical portion 32 . The coil case 30 forms a coil housing portion 44 that is open to the upper side of the case by the cylindrical portion 32, the bottom wall portion 38, and the first side wall portion 34 described above. A cylindrical winding portion 22 that constitutes the coil 20 is accommodated inside the coil accommodation portion 44 . When the winding portion 22 is housed in the coil housing portion 44 , the first side wall portion 34 is arranged along the outer circumference of the coil 20 (the winding portion 22 ) and a pair of lead terminal portions extending from the winding portion 22 . 24A and 24B are led out of the coil case 30 through terminal lead-out portions 40A and 40B integrally formed with the first side wall portion 34 .

Here, the terminal lead-out portions 40A and 40B are openings formed to allow communication between the inside and the outside of the coil housing portion 44, and are formed at two locations along the circumferential direction of the first side wall portion 34. As shown in FIG. The two terminal lead-out portions 40A and 40B are a first terminal lead-out portion 40A corresponding to the lead-out terminal portion 24A extending from the upper end of the winding portion 22 in the axial direction, and a lead-out terminal portion 24B extending from the lower end of the winding portion 22 in the axial direction. It is composed of a corresponding second terminal lead-out portion 40B. Further, terminal guide portions 42A and 42B for guiding the pair of lead terminal portions 24A and 24B, respectively, are provided integrally with the first and second terminal lead portions 40A and 40B.

The two terminal guide portions 42A and 42B project from the coil case 30 and have pedestals 421A and 421B and a pair of guide wall portions 422A and 422B, respectively. The pedestals 421A and 421B are formed in the shape of a table projecting radially outward from the outer periphery of the coil case 30, and cover the lower surfaces of the corresponding lead-out terminal portions 24A and 24B so as to be supported from below. ing. The pair of guide wall portions 422A and 422B extends radially outward in parallel from the outer periphery of the coil case 30, covers the side surfaces of the corresponding lead-out terminal portions 24A and 24B from both sides, and can restrict the rotation of the coil 20. It is configured. Furthermore, the terminal guide portions 42A and 42B are provided so as to protrude from the coil case 30, thereby effectively ensuring insulation between the lead terminal portions 24A and 24B.

The second side wall portion 36 is formed in a cylindrical shape having a larger diameter than the first side wall portion 34 and is arranged radially outward of the first side wall portion 34 . Specifically, the second side wall portion 36 includes a first arc portion 36A formed inside the two terminal guide portions 42A and 42B at the front of the case, and a second arc portion 36A formed outside the two terminal guide portions 42A and 42B. 2 circular arc portions 36B. The first and second arcuate portions 36A and 36B are wall portions curved in an arcuate shape when viewed from the axial direction of the coil case 30, and have two terminal guide portions 42A and 42B at both ends in the circumferential direction. It is connected with

Here, in the coil case 30 , the space formed between the first side wall portion 34 and the second side wall portion 36 is the core filling portion 46 . Specifically, the core filling portion 46 includes a first core filling portion 461 formed between the first side wall portion 34 and the first arc portion 36A, and a core filling portion 461 formed between the first side wall portion 34 and the second arc portion 36B. and a second core filling portion 462 formed in the second core filling portion 462, each forming a space penetrating in the vertical direction of the case. The first and second core filling portions 461 and 462 are filled with a magnetic resin that constitutes an outer peripheral core 60 to be described later, and are integrated with the coil case 30 .

Next, the core 50 attached to the coil 20 will be described. The core 50 includes an inner core 52 arranged inside the coil 20 and an outer core 54 arranged outside the coil 20 . As described above, the inner core 52 is formed in a columnar shape with an axial direction extending in the vertical direction, and is arranged inside the cylindrical portion 32 of the coil case 30 when assembled as the coil device 10 . It is arranged inside the winding part 22 . The inner core 52 is made of a powder compact.

Here, the compacted body is a magnetic body formed by mixing magnetic powder and a shape-retaining powdery binder (binding material), press-molding the mixed powder, and then sintering or heat-treating the mixed powder. is. In the present embodiment, the magnetic powder is composed of metallic magnetic powder containing iron as a main component. In the following, a powder compact made of metal-based magnetic powder will be referred to as a "metal powder compact", and a compact made of a magnetic material obtained by sintering ferrite will be referred to as a "ferrite powder compact". sintered body”.

The outer core 54 is composed of three core members consisting of an upper collar core 56 , a lower collar core 58 and an outer core 60 . The upper flange core 56 and the lower flange core 58 are formed in a disk shape with the plate thickness direction extending in the vertical direction, and are arranged at both upper and lower end portions of the inner core 52, respectively. Each of the upper collar core 56 and the lower collar core 58 is formed to have a larger diameter than the inner core 52, and when assembled as the coil device 10, the outer peripheral portions of the upper collar core 56 and the lower collar core 58 are positioned inside. It is configured to protrude like a flange from the outer peripheral surface of the core 52 . The upper collar core 56 and the lower collar core 58 are made of the same metal powder compact as the inner core 52 described above, and the outer surface is coated with an insulating coating agent to ensure insulation from the outside. 62 (see FIG. 2) is applied. 1 and 3, the coating agent 62 is omitted for illustration.

The outer core 60 is arranged along the outer circumference of the coil 20 and formed in a substantially cylindrical shape as a whole. The outer core 60 is made of magnetic resin. A magnetic resin is a magnetic material obtained by curing liquid resin mixed with magnetic powder. In this embodiment, after forming the coil case 30 by injection molding a resin material, the core filling portion 46 (461, 462) of the coil case 30 is filled with liquid magnetic resin and hardened. As a result, the outer core 60 integrated with the coil case 30 is formed by the magnetic resin filled in the core filling portion 46 (461, 462). When assembled as the coil device 10 , the outer core 60 is arranged along the outer periphery of the coil 20 so as to connect the upper collar core 56 and the lower collar core 58 . In this state, since the outer peripheral portion of the upper collar core 56 is arranged to cover the upper surface of the coil 20 , a ring-shaped insulating sheet 70 is placed on the coil 20 in order to ensure insulation between the coil 20 and the upper collar core 56 . and the upper collar core 56 .

In this embodiment, the magnetic powder contained in the magnetic resin is, for example, made of metal-based magnetic powder containing iron as a main component.

In the coil device 10 configured as described above, a magnetic circuit is formed that extends from the inner core 52 through the upper collar core 56 , the outer peripheral core 60 and the lower collar core 58 . In the magnetic circuit, the outer core 60 arranged along the outer periphery of the coil 20 has the largest outer diameter and has a complicated cylindrical shape. Therefore, in a large coil device that can handle a large current, it may be difficult to ensure the pressurizing ability of the press during pressure molding when trying to mold the outer core with a general compacted body. On the other hand, in the present embodiment, the outer core 60 is made of a magnetic resin, so that it can be molded into a desired shape and size by a method such as injection molding, and at the same time, mechanical strength can be ensured. there is

By the way, in a core made of a compacted body, processing distortion during molding can be removed by heat treatment, and core loss (magnetic loss) can be suppressed. On the other hand, a core made of a magnetic resin is distorted due to internal stress or the like when the liquid resin hardens, and it is difficult to suppress the core loss. Moreover, since a liquid resin is used as a binder, the distance between the particles of the magnetic powder becomes large, making it difficult to increase the magnetic permeability. Also, the influence of the diamagnetic field increases. Therefore, a core made of a magnetic resin tends to have lower magnetic properties such as magnetic permeability and core loss than a core made of a powder compact.

Therefore, the inventors have attempted to efficiently improve the magnetic characteristics of the coil device 10 in which the outer core 60 is made of a magnetic resin by combining different types of core materials made of a compact powder product or a magnetic resin. devised. In particular, since it is difficult to increase the volume of the inner core located inside the coil 20 due to restrictions on the placement space, it is assumed that a decrease in the magnetic properties of the inner core will greatly affect the magnetic properties of the entire core. be done. Therefore, as in the above embodiment, at least the inner core 52 arranged inside the coil 20 is made of a compacted body, thereby effectively improving the magnetic properties. The configurations and magnetic properties of Examples A to F of the present disclosure, including the above embodiments, will be described below.

FIG. 5 schematically shows a cross-section of the coil device 10 of Examples AC, in which the inner core 52 is composed of a metal compact.

[Example A]
As shown in FIG. 5A, in a coil device 10A according to Example A, an inner core 52, an upper collar core 56, and a lower collar core 58 are made of a metal powder compact, and an outer core 60 is made of a magnetic resin. It has a core 50 composed of In this embodiment A, the volume ratio of the core portion made of the metal powder compact to the magnetic path length of the magnetic circuit is about 73%.

[Example B]
As shown in FIG. 5B, in the coil device 10B according to the embodiment B, the inner core 52 and the lower collar core 58 are made of a metal compact, and the upper collar core 56 and the outer core 60 are made of magnetic resin. It has a configured core 50 . In this embodiment B, the volume ratio of the core portion made of the metal powder compact to the magnetic path length of the magnetic circuit is about 50%.

[Example C]
As shown in FIG. 5C, in a coil device 10C according to Example C, an inner core 52 is made of a metal powder compact, and an upper collar core 56, a lower collar core 58, and an outer core 60 are made of magnetic resin. It has a core 50 composed of In this embodiment C, the volume ratio of the core portion made of the metal powder compact to the magnetic path length of the magnetic circuit is about 27%.

Here, the magnetic properties of Examples A to C will be described in comparison with Comparative Examples A to C shown in FIG. The coil devices 300A to 300C according to Comparative Examples A to C have the same basic structure as the coil device 10 of the present embodiment, except that the inner core 302 is made of magnetic resin. different from C. In each figure shown in FIG. 8, the same components as those of the coil device 10 are denoted by the same reference numerals, and descriptions thereof are omitted.

[Comparative Examples A to C]
As shown in FIG. 8A, in a coil device 300A of Comparative Example A, an inner core 302 and an outer core 308 are made of magnetic resin, and an upper collar core 304 and a lower collar core 306 are made of a metal compact. It is In Comparative Example A, the volume ratio of the metal powder compact to the magnetic path length is about 46%.
As shown in FIG. 8B, in a coil device 300B of Comparative Example B, an inner core 302, an upper collar core 304, and an outer core 308 are made of magnetic resin, and a lower collar core 306 is made of a metal compact. It is In this comparative example B, the volume ratio of the metal powder compact to the magnetic path length is about 23%.
As shown in FIG. 8C, in a coil device 300C of Comparative Example C, an inner core 302, an upper collar core 304, a lower collar core 306, and an outer core 308 are made of magnetic resin. In Comparative Example C, the volume ratio of the metal powder compact to the magnetic path length is 0%.

Next, with reference to FIG. 9, the relationship between the volume ratio of the metal powder compact and the magnetic permeability of the entire core will be described for Examples A to C in comparison with Comparative Examples A to C. FIG. The horizontal axis in FIG. 9 represents the volume ratio [%] of the metal compact to the magnetic path length. The vertical axis in FIG. 9 represents the magnetic permeability μ [H/m] of the entire core when no current is applied. As shown in FIG. 9, when the magnetic permeability μ of Examples A to C is compared, the magnetic permeability μ of the entire core improves as the volume ratio of the metal powder compact to the magnetic path length increases. I understand.

Further, it can be seen that the magnetic permeability μ of Examples A to C exceeds those of Comparative Examples A to C in the entire numerical range shown in FIG. Therefore, for example, when comparing the magnetic permeability μ of Example C (FIG. 5C) and Comparative Example A (FIG. 8A), the volume ratio of the metal powder compact to the magnetic path length is While it is 27% in Example C, it is 46% in Comparative Example A. Although the volume ratio is larger than that in Example C, the magnetic permeability μ of the entire core is larger in Example C. value. Therefore, in Examples A to C, the inner core 52 arranged inside the coil 20 is made of a metal powder compact, so that the magnetic permeability μ of the entire core is more effective than in Comparative Examples A to C. It can be seen that the The relationship between the volume ratio occupied by the metal powder compact and the magnetic permeability of the entire core shown in FIG. relationship was shown.

Next, with reference to FIG. 10, the relationship between the volume ratio of the metal compact and the core loss of the entire core will be described for Examples A to C in comparison with Comparative Examples A to C. FIG. The horizontal axis in FIG. 10 represents the volume ratio [%] of the metal compact to the magnetic path length. The vertical axis in FIG. 10 represents the core loss Pcv [mW/cc] of the entire core. As shown in FIG. 10, when the core loss Pcv of Examples A to C is compared, the core loss Pcv of the entire core decreases as the volume ratio of the metal powder compact to the magnetic path length increases. I understand. Further, in the entire numerical range shown in FIG. 10, the values of core loss Pcv of Examples A to C are lower than those of Comparative Examples A to C. For this reason, as can be seen from the comparison of the core loss Pcv values of Example C (FIG. 5(C)) and Comparative Example A (FIG. 8(A)), the volume occupied by the metal compact in Comparative Example A is Although the ratio is large, the value of core loss Pcv in Example C shows a smaller value. Therefore, in Examples A to C, the core loss Pcv of the entire core is effectively reduced compared to Comparative Examples A to C by forming the inner core 52 arranged inside the coil with a metal powder compact. is found to be suppressed. Note that the relationship between the volume ratio of the metal compact and the core loss of the entire core shown in FIG. It has been shown.

Next, with reference to FIG. 11, the μ-H characteristics of Example A in which the inner core 52 is made of a powder compact (metal compact) will be described. The horizontal axis of FIG. 11 represents the magnetic field strength H [A/m], and the vertical axis of FIG. 11 represents the magnetic permeability μ [H/m] of the entire core. Further, in FIG. 11, the μ-H characteristic of Example A is indicated by a solid line, and the μ-H characteristic of Comparative Example C is indicated by a broken line. As shown in this figure, Example A shows a stable high magnetic permeability over a wide range, and it can be seen that the high magnetic permeability can be maintained even when a large current flows through the coil. Further, it can be seen that the magnetic permeability of Example A exceeds that of Comparative Example C in the entire numerical range shown in FIG.

Next, with reference to FIG. 12, the Pcv-Bm characteristics of Example A in which the inner core 52 is made of a powder compact (metal compact) will be described. The horizontal axis of FIG. 12 represents the magnetic flux density Bm [mT], and the vertical axis of FIG. 12 represents the core loss Pcv [mW/cc]. Further, in FIG. 12, the Pcv-Bm characteristic of Example A is indicated by a solid line, and the Pcv-Bm characteristic of Comparative Example C is indicated by a broken line. As shown in this figure, in Example A, compared with Comparative Example C, the increase in core loss Pcv accompanying the increase in magnetic flux density Bm is gentle. Further, the core loss of Example A is lower than the core loss of Comparative Example C in the entire numerical range shown in FIG. Therefore, it can be seen that Example A effectively suppresses an increase in core loss even when a large current flows through the coil.

Furthermore, the inventors have found that, from the viewpoint of magnetic permeability and low core loss in the low current region, generally, a powder compact made of a ferrite compact sintered compact has better magnetic properties than a metal compact. Focusing on the fact that the magnetic circuit is superior, the inventors have considered forming a magnetic circuit by combining core members made of ferrite powder sintered compacts.

On the other hand, the ferrite compact sintered body also has a magnetic property that the magnetic permeability decreases when a large current flows. Therefore, the inventors optimized the combination of a core member composed of a metal powder compact, a ferrite powder sintered compact, and a magnetic resin to improve magnetic properties and make it possible to handle large currents. have succeeded in devising a configuration of the core 50 that is

Hereinafter, Examples D to F in which the core 50 is constructed using a metal compact, a ferrite compact, and a magnetic resin will be described with reference to FIG.

[Example D]
As shown in FIG. 6A, in a coil device 10D according to Example D, an inner core 52 is made of a metal powder compact, and an upper flange core 56 and a lower flange core 58 are made of a ferrite powder sintered compact. , and the outer core 60 includes a core 50 made of a magnetic resin.

[Example E]
As shown in FIG. 6B, in the coil device 10E according to the embodiment E, the inner core 52 is made of a ferrite compacted sintered body, and the upper collar core 56 and the lower collar core 58 are made of a metal compacted body. , and the outer core 60 includes a core 50 made of a magnetic resin.

[Example F]
As shown in FIG. 6C, in a coil device 10E according to Example E, an inner core 52, an upper collar core 56, and a lower collar core 58 are made of a sintered ferrite compact, and an outer core 60 is made of a magnetic resin. It has a core 50 composed of

Next, referring to FIG. 13, the magnetic properties of Examples D to F will be described. FIG. 13 is a bar graph showing the magnetic properties of Example A in which the core 50 is composed of a metal compact and magnetic resin, and of Examples D to F above. In FIG. 13 , the value of the magnetic permeability μ0A/m [H/m] of the entire core when the coil 20 is not energized is represented by a solid line for each example. The value of magnetic permeability μ5000A/m [H/m] of the entire core is represented by a chain line, and the value of core loss Pcv [mW/cc] of the entire core is represented by a dashed line.

As shown in FIG. 13, the values of core loss Pcv of Examples D to F are lower than the value of core loss Pcv of Example A in which the core 50 does not contain a ferrite powder sintered compact. Therefore, it can be seen that the core loss Pcv can be suppressed by configuring a part of the core 50 with the ferrite powder sintered body.

Further, when comparing the value of the core loss Pcv of the entire core between Example D and Example E, Example D, in which the upper flange core 56 and the lower flange core 58 are made of a ferrite compacted powder sintered body, has only the inner core 52. The volume ratio of the ferrite powder sintered body to the magnetic path length is larger than that of Example E configured with the ferrite powder sintered body. However, since the value of the core loss Pcv is lower in Example E than in Example D, by placing the ferrite powder sintered body in the inner core 52, the magnetic properties of the ferrite powder sintered body are remarkable. can be seen to appear in

Furthermore, when comparing the values of core loss Pcv between Example E and Example F, compared with Example E in which only the inner core 52 is made of a ferrite compact sintered body, in addition to the inner core 52, the upper collar It can be seen that the value of core loss Pcv is even lower in Example F, in which both the core 56 and the lower collar core 58 are made of the ferrite powder compact sintered body.

It can be seen that the above tendency is the same for the value of the magnetic permeability μ0 A/m when no current is applied and the value of the magnetic permeability μ5000 A/m when a current of 5000 amperes is applied. That is, the values of the magnetic permeability μ0 A/m of Examples D to F are higher than the values of the magnetic permeability μ0 A/m of Example A in which the core 50 does not contain the ferrite compacted powder sintered body, and the ferrite compacted powder sintered compact is included. This characteristic appears remarkably by arranging it in the inner core 52 . In addition, in Examples D to F, the value of the magnetic permeability μ5000 A/m in the state where a large current is applied is higher than the value of the magnetic permeability μ5000 A/m in the example A in which the core 50 does not contain the ferrite powder sintered body. This characteristic appears conspicuously by arranging the ferrite compact sintered body in the inner core 52 .

Then, Examples E and F, in which the inner core 52 is made of a ferrite compact sintered body, are excellent in terms of lowering the value of the core loss Pcv, but they also have magnetic properties such that the magnetic permeability significantly decreases when a large current flows. Since it appears conspicuously, it is difficult to cope with a large current. On the other hand, Example D is superior to Example A in the value of core loss Pcv and the value of magnetic permeability μ0 A/m, and is equivalent to Example A in the value of magnetic permeability μ5000 A/m. Therefore, it can be seen that the configuration of Example D is optimized from the viewpoint of improving the magnetic properties and coping with large currents.

(Action and effect)
As described above, in the coil device 10 of the present embodiment, the inner core 52 is made of a compacted body (compressed sintered body), and in the outer core, at least the outer periphery arranged along the outer periphery of the coil By configuring the core with a magnetic resin, it is possible to cope with an increase in the size of the core and effectively improve the magnetic properties.

Further, in this embodiment, the outer core 54 is composed of an upper collar core 56 , a lower collar core 58 , and an outer core 60 . Therefore, the material of the upper flange core 56 and the lower flange core 58 can be changed from the outer core 60 made of magnetic resin, and the magnetic properties of the outer core 54 can be adjusted.

For example, like the coil device 10B of the embodiment B shown in FIG. Magnetic properties such as high magnetic permeability and low core loss can be obtained as compared with a configuration composed only of a magnetic resin.

Moreover, as in Example A shown in FIG. 5A and Example E shown in FIG. With this configuration, the magnetic characteristics corresponding to the magnetic characteristics of the metal powder compact can be enhanced as compared with the case where the outer core 54 is composed only of the magnetic resin.

Moreover, as in Example D shown in FIG. 6A and Example F shown in FIG. By forming the outer core 54 with the magnetic resin alone, the magnetic properties corresponding to the magnetic properties of the sintered ferrite compact can be enhanced.

Further, in the coil device 10 of the present embodiment, the coil case 30 and the outer core 60 are integrated. Specifically, the coil case 30 has a core filling portion 46 between the first side wall portion 34 and the second side wall portion 36 disposed radially outside the first side wall portion 34, and the outer core 60 is integrated with the coil case 30 by filling the core filling portion 46 with magnetic resin. As a result, the clearance between the coil case 30 and the outer core 60 can be reduced, and the size of the coil device 10 can be reduced. Further, since the side surface of the outer core 60 is covered with the side surface of the coil case 30, deterioration of the outer core 60 due to rust can be suppressed.

Furthermore, by reducing the clearance between the coil case 30 and the outer core 60, the magnetic path length of the magnetic circuit can be shortened, so that the AL value of the coil device 10 can be increased.

[supplementary explanation]
The present embodiment and each example have been described above, but in the present disclosure, the inner core and the outer core can be variously changed without departing from the gist of the present disclosure as to what kind of core material the inner core and the outer core are made of.

For example, the present disclosure includes a coil device 10G according to Example G shown in FIG. 7(A). The coil device 10G has an inner core 52G made of a metal compact, an upper flange core 56G, a lower flange core 58G and an outer core 60G made of magnetic resin. In the coil device 10G, both ends in the axial direction of the columnar inner core 52G are inserted through through holes 501 formed in the centers of the ring-shaped upper collar core 56G and lower collar core 58G. 7, the reference numerals of the coil 20 and the coil case 30 are omitted.

The present disclosure also includes a coil device 10H according to Example H shown in FIG. 7(B). The coil device 10H has an inner core 52H made of a metal compact, an upper flange core 56H, a lower flange core 58H and an outer core 60H made of magnetic resin. In the coil device 10H, both ends in the axial direction of the columnar inner core 52H are inserted into recesses 502 provided in the facing surfaces of the disk-shaped upper flange core 56H and lower flange core 58H.

The present disclosure also includes a coil device 10I according to Example I shown in FIG. 7(C). The coil device 10I has an inner core 52I, an upper collar core 56I, and a lower collar core 58I, which are made of a metal compact, and an outer core 60I and a frame core 503, which are made of magnetic resin. In the coil device 10I, a ring-shaped frame core 503 is arranged at both ends of a cylindrical outer core 60I, and a columnar inner core 52I and a columnar inner core 52I are arranged inside the frame core 503 at both ends of the inner core 52I. An upper collar core 56I and a lower collar core 58I are accommodated.

The present disclosure also includes a coil device 10J according to Example J shown in FIG. 7(D). The coil device 10J has an upper collar core 56J and a lower collar core 58J which are made of a metal compact, and an outer core 60J and a frame core 503 which are made of magnetic resin. In the coil device 10J, a ring-shaped frame core 503 is arranged at both ends of a cylindrical outer core 60J, and a columnar upper inner core 561J is integrally formed inside the frame core 503 to form an upper flange core 56J. A lower flange core 58J integrally formed with a columnar lower inner core 581J is accommodated. That is, the inner core arranged inside the coil is formed integrally with the upper collar core 56J and the lower collar core 58J. Further, in this case, a configuration may be adopted in which a predetermined gap is formed between the upper inner core 561J and the lower inner core 581J that constitute the inner core.

The present disclosure also includes a coil device 10K according to Example K shown in FIG. 7(E). The coil device 10K includes an inner core 52K made of a metal powder compact, an upper flange core 56K and a lower flange core 58K made of a ferrite powder sintered compact, an outer peripheral core 60K made of a magnetic resin, and It has a frame core 503 . In the coil device 10K, a ring-shaped frame core 503 is arranged at both ends of a cylindrical outer core 60K, and a columnar inner core 52K is arranged inside the coil inside the frame core 503. A disk-shaped upper flange core 56K and a lower flange core 58K are arranged at both ends.

The present disclosure also includes a coil device 10L according to Example L shown in FIG. 7(F). The coil device 10L includes an inner core 52L made of a metal powder compact, an upper collar core 56L and a lower collar core 58L made of a ferrite powder sintered body, an outer peripheral core 60L made of a magnetic resin, and It has a frame core 503 . In the coil device 10L, a ring-shaped frame core 503 is arranged at both ends of a cylindrical outer core 60L, and a columnar inner core 52L is arranged inside the coil inside the frame core 503. An upper collar core 56L integrally formed with a columnar upper inner core 561L and a lower collar core 58L integrally formed with a columnar lower inner core 581L are arranged so as to sandwich 52L from both sides.

The present disclosure also includes a coil device 10M according to Example M shown in FIG. 7(G). The coil device 10M is composed of an inner core 52M made of a metal compact, an upper collar core 56M, a lower collar core 58M, and an outer core 60M made of magnetic resin, and a ferrite compact sintered body. and a central core 504 . In the coil device 10M, a columnar inner core 52M is arranged inside the coil, and a ring-shaped upper collar core 56M and a ring-shaped lower collar core 58M are respectively arranged at both ends of the inner core 52M. Furthermore, disc-shaped central cores 504 are arranged in through holes 501 formed in the central portions of the upper collar core 56M and the lower collar core 58M.

The present disclosure also includes a coil device 10N according to Example N shown in FIG. 7(H). The coil device 10N has an inner core 52N made of a sintered ferrite compact, an upper collar core 56N, a lower collar core 58N, and an outer core 60N made of magnetic resin. In the coil device 10N, a disk-shaped upper flange core 56N and a disk-shaped lower flange core 58N are arranged at both ends of a columnar inner core 52N.

The present disclosure also includes a coil device 10P according to Example P shown in FIG. 7(I). The coil device 10P has an upper collar core 56P and a lower collar core 58P made of ferrite powder sintered compacts, and an outer peripheral core 60P and a frame core 503 made of magnetic resin. In the coil device 10P, a ring-shaped frame core 503 is arranged at both ends of a cylindrical outer core 60P, and a columnar upper inner core 561P is integrally formed inside the frame core 503 to form an upper flange core 56P. A lower flange core 58P integrally formed with a columnar lower inner core 581P is accommodated. That is, the inner core arranged inside the coil is formed integrally with the upper collar core 56P and the lower collar core 58P. Further, in this case, a configuration may be adopted in which a predetermined gap is formed between the upper inner core 561P and the lower inner core 581P that constitute the inner core.

In the coil case 30 of the above embodiment, the core filling portion 46 formed between the first side wall portion 34 and the second side wall portion 36 is filled with magnetic resin to form the outer core 60, but the present disclosure is not limited to this. From the viewpoint of ensuring insulation between the coil 20 and the outer core 60, the outer core may be configured integrally with the first side wall, and the coil case may be configured without the second side wall.

Although the coil device of the above embodiment is a choke coil, the configuration of the coil device of the present disclosure is not limited to this, and can be applied to a coil device such as a transformer. That is, the primary coil and the secondary coil formed in a cylindrical shape may be stacked and housed in the coil housing portion 44 of the coil case 30 via an insulating member.

Moreover, the winding of the coil is not limited to the copper plate, and may be composed of wire or litz wire. Further, in the embodiment and each example, a metal powder compact containing a magnetic powder containing iron as a main component was described as an example, but the present disclosure is not limited to this, and a metal compact containing a known metal-based magnetic powder Powder compacts can be combined as appropriate.

10 coil device (10A ~ 10N, 10P)
20 coil 52 inner core 54 outer core 60 outer core 56 upper flange core 58 lower flange core 30 coil case 32 tubular portion 34 first side wall portion 36 second side wall portion 46 core filling portion (461, 462)

Claims (7)

a tubular coil;
a columnar inner core arranged inside the coil;
an outer core arranged outside the coil,
The inner core is composed of a powder compact,
The outer core has an outer core disposed along the outer periphery of the coil, and at least the outer core is made of a magnetic resin obtained by mixing magnetic powder and liquid resin and hardening the coil device. The outer core is arranged along the outer periphery of the coil so as to connect the plate-shaped upper and lower collar cores respectively arranged at both ends of the inner core, and the upper and lower collar cores. 2. The coil device according to claim 1, further comprising the outer peripheral core. One of the upper brim core and the lower brim core is made of the magnetic resin, the other of the upper brim core and the lower brim core is made of a powder compact,
The coil device according to claim 2, wherein the outer core is made of the magnetic resin. The upper brim core and the lower brim core are composed of powder compacts made of metal compacts,
The coil device according to claim 2, wherein the outer core is made of the magnetic resin. The upper collar core and the lower collar core are composed of a compacted body made of a magnetic material obtained by sintering ferrite,
The coil device according to claim 2, wherein the outer core is made of the magnetic resin. The outer core is formed integrally with a coil case that houses the coil,
The coil case is
a cylindrical portion around which the coil is wound;
The coil device according to any one of claims 2 to 5, further comprising a first side wall portion arranged along the outer circumference of the coil and integrated with the outer circumference core. The coil case further includes a second side wall portion arranged radially outward of the first side wall portion, and a core filling portion formed between the first side wall portion and the second side wall portion. death,
7. The coil device according to claim 6, wherein said outer peripheral core is formed by filling said core filling portion with a magnetic resin.

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