CN106486268B - Coil device - Google Patents

Abstract

The invention provides a coil device which can simultaneously ensure direct current superposition characteristics and high inductance and can easily realize miniaturization. The coil device has: a middle core portion (12); a pot core (10) having a side wall portion (14) surrounding the core portion (12) at a predetermined interval; and a cover core (30) that covers the upper portions of the middle core section (12) and the coil section (20). The coil part (20) is formed by edgewise winding a wire (22) having a flat cross section into two or more layers. The winding wire (22) is directly wound around the winding core (12).

Description

Coil device

Technical Field

The present invention relates to a coil device that can be preferably used for applications such as a choke coil for a vehicle.

Background

As a surface-mount choke coil, for example, a coil device shown in patent document 1 is known. As shown in patent document 1, a coil device is known in which a rectangular conductor is wound around a pot core (pot core) in a edgewise manner.

However, in such a conventional coil device, it is difficult to simultaneously secure a dc superimposition characteristic and a high inductance. In addition, in the conventional coil device, the rectangular conductor is wound in one layer in a flat manner. Therefore, one lead portion of the rectangular conductor constituting the coil portion is located at the bottom of the can core, and the lead portion needs to be drawn therefrom. Therefore, an extra space is required for drawing the lead portion, and it is difficult to realize a small-sized high-inductance coil device.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 11-307357

Disclosure of Invention

The present invention has been made in view of such circumstances, and an object thereof is to provide a coil device that can easily achieve miniaturization while ensuring both dc superimposition characteristics and high inductance.

In order to achieve the above object, a coil device according to the present invention includes:

a middle core part;

a pot core having a side wall portion surrounding the center core portion at a predetermined interval;

a coil portion disposed between the center core portion and the side wall portion; and

a cover core covering an upper portion of the coil part and an upper portion of the middle core part,

the coil part is formed by winding a winding having a flat cross section in a flat manner into two or more layers,

the pair of lead portions at both ends of the winding are led out from the upper end of the side wall portion to the outside.

In the coil device according to the present invention, the coil portion is configured by edgewise winding a winding having a flat cross section in even-numbered layers into two or more layers. Therefore, both end portions of the winding, i.e., both the pair of lead portions, are positioned at the upper end of the coil portion, and can be easily drawn out from the upper end of the side wall portion of the can core to the outside without requiring an extra space inside the can core. Therefore, the inductance of the coil device can be increased, and the coil device can be made smaller and thinner.

Further, since an extra space for drawing the lead portion is not required inside the can core, the distance between the outer periphery of the coil portion and the side wall portion of the can core is kept constant, and the gap between the cover core and the side wall portion of the can core is easily adjusted to a constant interval. Therefore, the distance between the members constituting the core can be easily controlled, magnetic saturation can be improved, and dc superimposition characteristics can be improved.

Preferably, the bottom portion of the middle core portion is fixed to the bottom plate portion of the can core in a state where the coil portion is mounted on the outer periphery of the middle core portion. That is, the coil portion is not mounted inside the can core as an air-core coil, but is disposed inside the can core in a state of being wound around the center core portion, so that the distance between the center core portion and the coil portion is shortened, and the dc superimposition characteristic can be improved.

The bottom of the center core portion may also be fixed to the bottom plate portion of the tank core by an adhesive. Alternatively, the bottom of the middle core portion may be fixed to the bottom plate portion of the tank core by a resin containing a magnetic material. With this configuration, the distance between the center core portion and the pot core can be adjusted to easily adjust the characteristics, and the degree of freedom in design is improved. Further, the bottom of the center core portion is bonded to the bottom plate portion of the can core using a resin containing a magnetic material, whereby inductance can be easily improved.

The magnetic properties of the center core portion and the magnetic properties of the pot core may be made different. For example, the dc superimposition characteristics can be improved by selecting a combination of magnetic materials such that the magnetic permeability μ of the pot core is higher than the magnetic permeability μ of the core portion and the saturation magnetic flux density Bs of the core portion is higher than the saturation magnetic flux density Bs of the pot core.

For example, it is preferable that the can core be made of a magnetic material composed of a metal sintered body, and the middle core be made of a magnetic material composed of a powder compact of an iron-based metal powder and a resin. The lid core is preferably made of the same magnetic material as the can core.

The bottom of the center core portion may be formed integrally with the bottom plate portion of the pot core. In this case, the hollow coil is disposed around the center core.

Preferably, the pair of lead portions of the winding are led out to the outside of the side wall portion in the vicinity of the upper end of the coil portion, and lead grooves for leading out the lead portions to the outside are formed in the upper end of the side wall portion. By forming the lead groove, a uniform interval is easily formed in the circumferential direction between the outer periphery of the lid core and the side wall portion of the can core, and the dc superimposition characteristic is improved.

Preferably, the pair of lead portions of the winding are led out to the outside of the side wall portion at a predetermined angle of 20 to 60 degrees, respectively, and are connected to a pair of terminals attached to the outer surface of the side wall portion. With this configuration, the winding wire having a flat cross section can be easily wound in two layers around the core portion, and insulation between the pair of terminals can be easily secured.

Preferably, the terminal has:

a terminal body mounted on an outer peripheral surface of the side wall portion;

a lower locking piece formed at the lower end of the terminal body and locked to the lower end surface of the side wall portion;

an upper locking piece formed at the upper end of the terminal body and locked to the upper end surface of the side wall;

a setting piece configured at the outer side of the lead slot;

and a connecting piece integrally connecting the installation piece and the terminal main body.

By providing such a terminal, the coil device can be easily miniaturized, and the lead portion and the terminal can be easily electrically and mechanically connected to each other. These connections are made by, for example, laser welding or spot welding.

Drawings

Fig. 1 is an overall perspective view of a coil device according to an embodiment of the present invention.

Fig. 2A is an exploded perspective view of the coil device shown in fig. 1.

Fig. 2B is a bottom view of the coil part wound directly around the center part shown in fig. 2A.

Fig. 2C is a perspective view of the pot core shown in fig. 2A as viewed from the lower side in the Z-axis direction.

Fig. 2D is a perspective view showing a modification of the terminal shown in fig. 2A.

Fig. 3A is a schematic sectional view taken along the line III-III shown in fig. 1.

Fig. 3B is a schematic cross-sectional view of a coil device according to another embodiment of the present invention.

Fig. 3C is a schematic cross-sectional view of a coil device according to still another embodiment of the present invention.

Fig. 4 is an exploded perspective view of the coil device shown in fig. 3C.

Fig. 5(a) and 5(B) are cross-sectional views showing examples of cross-sections of the windings.

Description of the symbols

2. 2a … coil device

10 … Can core

11 … bottom plate part

12. 12A … center core

12a … upper end

14 … side wall part

14a … upper end

14d, 14e … lead-out groove (notch groove)

18 … recess

18a … inner bottom surface

20. 20a … coil part

22 … wound wire

22a, 22b … lead part

30. 30a … cover core

32 … inner face

34 … outside

36 … outer peripheral surface

40a, 40b, 40c … terminal

41a, 41b, 41c … terminal body

42a, 42b, 42c … lower locking piece

43a, 43b, 43c …

44a, 44b, 44c … connecting piece

46a, 46b, 46c … arrangement sheet

50 … first adhesive

52 … second adhesive.

Detailed Description

The present invention will be described below based on embodiments shown in the drawings.

First embodiment

As shown in fig. 1, the coil device 2 according to the present embodiment is a coil device used as an in-vehicle choke coil or the like used for, for example, an idle stop (idlingstop) or a fuel pump, and includes a can core 10, a cover core 30, and terminals 40a and 40 b.

As shown in fig. 2A and 3A, the can core 10 includes a circular bottom plate 11 and a side wall 14 formed to rise in the Z-axis direction from the outer periphery of the bottom plate 11. Inside the pot core 10, a cylindrical recess 18 is formed by the bottom plate 11 and the side wall.

A columnar core 12 is disposed inside the recess 18 of the can core 10, and the bottom of the core 12 is fixed to the substantially central portion of the bottom plate 11 of the can core 10 with a second adhesive 52 or the like. The center core portion 12 has an axial core in the Z-axis direction, and a coil portion 20 is disposed on the outer periphery of the center core portion 12.

As shown in fig. 2A and 2B, the coil portion 20 is configured by edgewise winding a wire 22 having a flat cross section into two or more layers, and is directly wound around the outer periphery of the center core portion 12. As shown in fig. 5(a) and 5(B), the winding 22 may have a rectangular cross-sectional shape, an elliptical cross-sectional shape, or any other shape as long as it has a flat cross-section whose lateral width w is larger than the thickness t.

The aspect ratio t/w is preferably 0.05 to 0.9, and more preferably 0.5 to 0.8. As a representative winding 22 having a flat cross section, a straight-angled winding can be exemplified. The periphery of the winding 22 is covered with an insulating film 24.

The edgewise winding is a winding method in which the short side (thickness t side) of the winding 22 having a flat cross section is longitudinally wound with the inner diameter surface. As shown in fig. 2A and 2B, the winding wire 22 is wound around the outer periphery of the middle core portion 12 in two or more layers. When the core portion 12 is wound around at least two layers, the concave portions 13a and 13b formed on both end surfaces of the core portion 12 in the Z-axis direction function as fixing portions and the like.

In the present embodiment, the coil portion 20 is wound around the outer peripheral portion of the middle core portion 12 in advance in an even-numbered layer coil shape of two or more layers of the wire 22 so that the pair of lead portions 22a, 22b are drawn out to the upper portion in the Z-axis direction. The lead portions 22a and 22b form both ends of the winding 22. The winding 22 may be formed of a single wire or a twisted wire, and is preferably formed of an insulated covered wire.

The inner peripheral surface of the side wall portion 14 is a cylindrical outer peripheral surface, and the outer peripheral surface is a prismatic outer peripheral surface, and in the present embodiment, the outer peripheral surface of the side wall portion 14 has a shape in which chamfered outer peripheral surfaces 14b are formed at the corners of two adjacent portions of a quadrangular prism, and has an outer peripheral surface shape of a hexagonal prism as a whole. As shown in fig. 3A, the upper end 14a of the side wall portion 14 in the Z-axis direction is located higher than the upper end 12a of the center core portion 12 in the Z-axis direction. In the figure, the Z axis is a direction that coincides with the axial center of the center core 12 of the can core 10, and also coincides with the winding axis of the coil section 20. Axes perpendicular to the Z axis are defined as an X axis and a Y axis, and the terminals 40a and 40b are arranged facing each other in the X axis direction.

As shown in fig. 2A, the pair of terminals 40a and 40b have flat plate-like terminal main bodies 41a and 41b that are in close contact with the opposing outer peripheral surfaces 14c of the side wall portions 14 in the Z-axis direction, respectively. Lower locking pieces 42a, 42b are formed integrally with the main bodies 41a, 41b at the lower ends of the terminal main bodies 41a, 41b in the Z-axis direction so as to be in close contact with the lower surface of the side wall portion 14, respectively. The lower locking pieces 42a and 42b are set to have a length such that they do not contact each other on the lower surface of the bottom plate 11 and are short-circuited.

Two locking protrusions 16a, 16C that fit into the outer two recesses 15a, 15C of the three locking recesses 15a, 15b, 15C (see fig. 2C) formed in the Y-axis direction on the lower end surface of the corresponding side wall portion 14 are formed on the inner surface of each of the lower locking pieces 42a, 42 b. As shown in fig. 2C, the locking recesses 15a, 15b, and 15C may be formed on a surface 10b recessed from the outer bottom surface 10a of the can core 10. The surface 10b has a shape matching the shape of the lower locking pieces 42A and 42b, respectively, as shown in fig. 2A.

Upper locking pieces 43a, 43b are formed integrally with the main bodies 41a, 41b at the upper ends of the terminal main bodies 41a, 41b in the Z-axis direction so as to be in close contact with a stepped surface 14a1 that is lower by one step than the upper end 14a of the side wall portion 14. The upper locking pieces 43a and 43b are set to have a length such that they do not contact each other and are short-circuited.

Locking projections 19a, 19b are formed on the inner surfaces of the upper locking pieces 43a, 43b, and the locking projections 19a, 19b are fitted into locking recesses 17a, 17b formed on a stepped surface 14a1 that is lower by one step than the upper end 14a of the side wall portion 14 shown in fig. 2A. The upper surfaces of the upper locking pieces 43a and 43b attached to the stepped surface 14a1 are substantially flush with the upper end 14a of the side wall portion 14.

Further, coupling pieces 44a, 44b protruding toward the chamfered outer peripheral surface 14b are formed integrally with the main bodies 41a, 41b, respectively, at intermediate positions in the Z-axis direction of the terminal main bodies 41a, 41 b. On the upper portion of the tip end side of each of the coupling pieces 44a and 44b, there are formed mounting pieces 46a and 46b substantially perpendicular to the Z axis. The upper surfaces of the installation pieces 46a and 46b are designed to be substantially flush with the groove bottom surfaces of the slit-shaped grooves (lead grooves) 14d and 14e formed in the upper portions of the chamfered outer peripheral surfaces 14 b.

Lead portions 22a and 22b extending outward from the slit-shaped grooves 14d and 14e are provided on the upper surfaces of the installation pieces 46a and 46b, and the installation pieces 46a and 46b are electrically connected to the lead portions 22a and 22 b. The leading end portions of the lead portions 22a and 22b are joined to the mounting pieces 46a and 46b by solder welding, laser welding, arc welding, or the like. In the drawing, the leading end portions of the lead portions 22a and 22b are connected to the installation pieces 46a and 46b by laser welding, respectively, and are drawn so as to form welded balls.

As shown in fig. 3A, the inner bottom surface 18a of the recess 18 is also the upper surface of the bottom plate 11, but is flat so that the lower surface 12b of the core 12 and the lower surface of the coil part 20 are easily bonded to each other via the second adhesive 52. The adhesive 52 also enters the concave portion 13b of the core 12, and the joint between the core 12 and the can core 10 is strengthened. The height H3 from the inner bottom surface 18a of the can core 10 to the slit-shaped grooves 14d, 14e is preferably a height sufficient for housing the coil section 20.

In fig. 3A, the height H1 is the height from the inner bottom surface 18a to the upper end 12a of the core 12, and is preferably smaller than the height H0 of the side wall portion 14, the dimension of the height H0 minus the height H1 is preferably substantially equal to the thickness of the lid core 30 in the Z-axis direction, and the outer surface 34 of the lid core 30 and the upper end 14a of the side wall portion 14 are preferably substantially flush with each other.

A first adhesive agent 50 is interposed between the inner surface 32 of the cover core 30 and the upper ends of the core portion 12 and the coil portion 20 to secure the bonding therebetween. The first adhesive 50 constitutes a first gap G1 between the cover core 30 and the center core 12. The first adhesive 50 also fills the recess 13a, and thus the joint between the cover core 30 and the center core 12 is strengthened. The first gap G1 is not particularly limited, but is preferably 1mm or less, and more preferably 0.05 to 0.3 mm. By setting in such a range, the thinning and the balance of the characteristics are excellent.

The outer peripheral surface 36 of the cover core 30 is preferably formed into a circumferential surface shape in conformity with the shape of the inner peripheral surface of the side wall portion 14, and may be in close contact with the inner peripheral surface of the side wall portion 14 as shown in fig. 1, but may be provided with a predetermined air gap G2 as shown in fig. 3A and 3C.

In fig. 3A, the height H2 is a height from the inner bottom surface 18a to the upper end of the coil portion 20, and is substantially the same as the height of the coil portion 20 itself in the Z axis direction if the thickness of the second adhesive 52 is considered to be small. In the present embodiment, since the lead portions 22a and 22b are formed near the upper end of the coil portion 20, the height H3 is substantially the same as or slightly smaller than the height H2, but the height H3 may be smaller than the height H2 when the lead portions 22a and 22b are formed in the middle of the coil portion 20 in the Z-axis direction.

The second adhesive 52 is filled not only between the inner bottom surface 18a of the can core 10 and the lower surfaces of the middle core portion 12 and the coil portion 20, but also between the outer peripheral surface of the coil portion 20 and the inner peripheral surface of the side wall portion 14.

The first adhesive 50 and the second adhesive 52 may be made of the same material or different materials, but are made of a common adhesive having the same basic composition and containing no magnetic powder, such as an epoxy adhesive, a silicon adhesive, a polyimide adhesive, a cyanoacrylate adhesive, a modified acrylic adhesive, or the like.

Alternatively, the first adhesive 50 and the second adhesive 52 may be a magnetic material-containing resin containing a magnetic material powder in a resin such as epoxy or silicon. The magnetic powder may be the same magnetic material as that constituting the can core 10 or the lid core 30, or may be a different magnetic material, and for example, a metal magnetic material containing Fe, Si, Cr, B, C, or the like may be used.

The content of the magnetic powder contained in the magnetic material-containing resin is preferably the same in the first binder 50 and the second binder 52, but may be different within a predetermined range. For example, the content of the magnetic powder contained in each of the first binder 50 and the second binder 52 is preferably 80 to 90 wt% with respect to the whole.

The pot core 10 and the lid core 30 are preferably made of the same magnetic material, but may be made of different magnetic materials. The can core 10 and the lid core 30 are each preferably a FeSiCr-based metal magnetic material, for example, and are preferably magnetic materials obtained by heat-treating a powder compact of metal powder at a high temperature (e.g., 700 ℃).

In the present embodiment, the middle core portion 12 is preferably a magnetic body different from the can core 10 and the cover core 30. For example, a compact of iron-based metal powder and resin (e.g., epoxy 3%) is preferable, and a magnetic body obtained by curing resin at 150 ℃ is preferable.

This combination of magnetic materials is an example of a combination of magnetic materials such that the magnetic permeability μ of the pot core 10 is higher than the magnetic permeability μ of the core 12, and the saturation magnetic flux density Bs of the core 12 is higher than the saturation magnetic flux density Bs of the pot core 10.

The second adhesive 52 before curing shown in fig. 3A may be filled in the inner bottom surface 18a of the recess 18 by a predetermined amount before the middle core part 12 and the coil part 20 shown in fig. 2A are inserted into the recess 18, and then the coil part 20 may be inserted into the recess 18 together with the middle core part 12. The adhesive 52 before curing is preferably adjusted so that the resin filled in advance moves so as to spread over the gap between the outer peripheral surface of the coil portion 20 and the inner wall surface of the side wall portion 14, and stops before overflowing from the slit-shaped grooves 14d, 14 e.

The first adhesive 50 before curing may be applied to the inner surface 32 of the cover core 30 or the upper end 12a of the middle core portion 12 in advance, and then bonded thereto. The curing treatment of the first adhesive 50 and the second adhesive 52 may be performed by heating if the resin constituting these adhesives is a thermosetting resin, as shown in fig. 3A, preferably at the same time after assembly. However, the curing treatment may be performed separately.

As shown in fig. 3A, the terminals 40a and 40b shown in fig. 2 may be mounted after the curing process of the first adhesive 50 and the second adhesive 52 is completed, or may be mounted before. The joining of the leading ends of the lead portions 22a, 22b and the setting pieces 46a, 46b is performed after the mounting of the terminals 40a, 40 b.

In the coil device 2 according to the present embodiment, the resin included in the first adhesive 50 functions as the first gap G1, magnetic saturation is improved, and dc superimposition characteristics are improved. In addition, when the magnetic material is contained in the first adhesive 50, the magnetic material in the adhesive functions as a part of the core portion 12 (or the cover core 30), and the inductance is improved.

In the present embodiment, the air gap G2 is formed between the inner peripheral surface of the side wall portion 14 and the outer peripheral surface 36 of the cover core 30, so that the magnetic saturation is further improved and the dc superimposition characteristic is further improved.

In the present embodiment, as shown in fig. 3A, a second adhesive 52 is interposed between the lower surface 12b and the inner bottom surface 18a of the core portion 12, and a space is formed therebetween. Therefore, the dc superimposition characteristic can be further improved. In addition, when the second binder 52 contains magnetic powder, the inductance is further improved.

In the present embodiment, lead portions 22a and 22b of the winding 22 constituting the coil portion 20 are drawn out to the outside of the side wall portion 14 in the vicinity of the upper end of the coil portion 20, and grooves 14d and 14e for drawing out the lead portions 22a and 22b to the outside are formed in the upper end 14a of the side wall portion 14.

With this configuration, the second adhesive 52 can be filled in the gap between the inner wall surface of the recess 18 and the outer surface of the coil portion 20 to the maximum height. Further, by filling the recess 18 with the second adhesive 52 to the extent that it is not discharged to the outside through the cells 14d and 14e, the second adhesive 52 can be filled in the gap between the inner wall surface of the recess 18 and the coil part 20 to the maximum height only by housing the middle core part 12 together with the coil part 20 in the recess 18.

In the present embodiment, the first adhesive agent 50 is disposed at a position higher than the second adhesive agent 52 in the Z-axis direction, and thus a space is easily formed between the upper end of the coil portion 20 and the inner surface 32 of the cover core 30.

In particular, in the coil device 2 according to the present embodiment, as shown in fig. 2A and 2B, the coil unit 20 is configured by edgewise winding the wire 22 having a flat cross section in even-numbered layers into two or more layers. Therefore, both end portions of the winding 22, i.e., both the pair of lead portions 22a and 22b, are positioned at the upper end of the coil portion 20, and can be easily drawn out from the upper end of the side wall portion 14 of the can core 10 to the outside without requiring an extra space inside the can core 10. Therefore, the inductance of the coil device 2 can be increased, and the coil device 2 can be made smaller and thinner.

Further, since no extra space for drawing the lead portion is required inside the can core 10, the distance between the outer periphery of the coil portion 20 and the side wall portion 14 of the can core 10 is kept constant, and the gap between the cover core 30 and the side wall portion 14 of the can core 10 is easily adjusted to a constant gap G2. Therefore, the distance between the members constituting the core can be easily controlled, magnetic saturation can be improved, and dc superimposition characteristics can be improved.

In the present embodiment, the coil part 20 is not mounted as an air-core coil inside the can core 10, but is disposed inside the can core 10 in a state of being wound around the center core part 12, so that the distance between the center core part 12 and the coil part 20 is shortened, and the dc superimposition characteristic can be improved.

In the present embodiment, the magnetic properties of the center core portion 12 and the magnetic properties of the can core 10 and the cover core 30 are easily made different from each other. For example, the dc superimposition characteristics can be improved by selecting a combination of magnetic materials such that the magnetic permeability μ of the can core 10 and the lid core 30 is higher than the magnetic permeability μ of the core 12 and the saturation magnetic flux density Bs of the core 12 is higher than the saturation magnetic flux density Bs of the can core 10 and the lid core 30.

In the present embodiment, the pair of lead portions 22a and 22b of the winding 22 are drawn out to the outside of the side wall portion 14 at a predetermined angle of 20 to 60 degrees, preferably at an angle of 40 to 50 degrees. With this configuration, the winding wire 22 having a flat cross section can be easily wound in two layers around the center core 12, and insulation between the pair of terminals 40a and 40b can be easily ensured.

By providing such terminals 40a and 40b, the coil device 2 can be easily downsized, and the lead portions 22a and 22b and the terminals 40a and 40b can be easily electrically and mechanically connected. These connections can be made by, for example, solder welding or laser welding, or arc welding.

Second embodiment

As shown in fig. 2D, the coil device according to the present embodiment differs from the first embodiment only in the structure of the terminal 40c and the terminals 40a and 40b, and has the same operational advantages as the above-described embodiment in other parts. Hereinafter, only different portions will be described.

As shown in fig. 2D, the terminal 40c of this embodiment has a flat plate-like terminal main body 41c that is in close contact with the opposing outer peripheral surface 14c of the side wall portion 14 shown in fig. 2A in the Z-axis direction. A lower locking piece 42c is integrally formed at the lower end of the terminal body 41c in the Z-axis direction. The lower locking piece 42c shown in fig. 2D corresponds to the lower locking pieces 42A and 42b shown in fig. 2A, and has a width in the Y-axis direction shorter than the width of the lower locking pieces 42A and 42b shown in fig. 2A.

A single locking convex portion 16b is formed on the inner surface of the lower locking piece 42C shown in fig. 2D, and this locking convex portion 16b is fitted into the locking concave portion 15b located at the center in the Y axis direction among the locking concave portions 15a to 15C shown in fig. 2C. The upper locking piece 43c, the connecting piece 44c, and the installation piece 46c shown in fig. 2D have the same configuration as the connecting pieces 44a and 44b and the installation pieces 46a and 46b of the first embodiment, and therefore, the description thereof is omitted.

The terminal 40c of the present embodiment can be used in place of the terminals 40a and 40b of the first embodiment, and the core 10, the cover core 30, the center core portion 12, and the coil portion 20 can be shared.

Third embodiment

The coil device according to the present embodiment shown in fig. 3B is different from the cover core 30 of the first embodiment only in the structure of the cover core 30a, and the other portions are common to the above-described embodiments, and the same operational effects can be achieved. Hereinafter, only different portions will be described.

As shown in fig. 3B, a plurality of interval-adjusting projections 33 are formed on the inner surface 32 of the cover core 30a of the present embodiment, and the first interval G1 shown in fig. 3A can be adjusted to a predetermined value by the projections 33 coming into contact with the upper end 12a of the center core portion 12. From this viewpoint, it is preferable that the projection height H1 of the convex portion 33 from the inner surface 32 is substantially equal to the first interval G1 shown in fig. 3A.

The inner surface 32 of the cover core 30a and the upper end 12a of the middle core portion 12 may be bonded together with an adhesive containing no magnetic powder. This point is also the same in other embodiments.

Fourth embodiment

As shown in fig. 3C and 4, the coil device 2A according to the present embodiment differs from the coil device 2A according to the above-described embodiment in that it is formed integrally with the bottom plate 11 of the can core 10a only at the bottom of the core 12A, and the coil portions 20a each including an air-core coil are arranged around the core 12A, and the other portions are common to the above-described embodiment, and similar operational effects can be achieved. Hereinafter, only different portions will be described.

As shown in fig. 3C, the bottom of the center core 12A is formed integrally with the bottom plate 11 of the can core 10 a. Therefore, as shown in fig. 4, it is difficult to directly wind the flat-section wire 22 around the middle core portion 12A, and an air-core coil formed in advance in a coil shape is used as the coil portion 20 a.

Even in the coil portion 20a formed of the air-core coil, the winding 22 having a flat cross section is wound in a flat manner into an even number of windings of two or more layers. In order to insert the coil part 20a composed of a pre-formed air-core coil into the annular gap between the central core part 12A and the side wall part 14, the inner diameter D2 of the coil part 20a is preferably slightly larger than the outer diameter D1 of the central core part 12A, and the outer diameter D2 of the coil part 20a is preferably slightly smaller than the inner diameter D1 of the inner peripheral surface of the side wall part 14.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention.

Claims (7)

1. A coil device is characterized in that,

comprising:

a middle core part;

a pot core having a side wall portion surrounding the center core portion at a predetermined interval;

a coil portion disposed between the center core portion and the side wall portion; and

a cover core covering an upper portion of the coil part and an upper portion of the middle core part,

the coil portion is formed by edgewise winding a winding wire having a flat cross section into two or more even-numbered layers and a pair of lead portions as both end portions of the winding wire are respectively led out to the outside of the side wall portion at a position of an upper end of the coil portion,

lead grooves for leading out the pair of lead portions to the outside of the side wall portion at the position of the upper end of the coil portion are formed in the upper end of the side wall portion,

an adhesive is filled between an inner peripheral surface of the side wall portion and an outer peripheral surface of the coil portion to a height of a bottom surface of the lead groove,

an outer peripheral surface of the lid core is formed in a shape matching an inner peripheral surface of the side wall portion of the pot core so that a predetermined air gap is formed along a circumferential direction between the outer peripheral surface of the lid core and the inner peripheral surface of the side wall portion of the pot core,

a gap is formed between the inner surface of the cover core and the upper ends of the middle core part and the coil part with an adhesive interposed therebetween,

the pot core and the lid core have higher magnetic permeability than the middle core, and the middle core has higher saturation magnetic flux density than the pot core and the lid core,

chamfered outer peripheral surfaces are formed on the outer peripheral surfaces of the side wall portions at the corners of two adjacent portions of the quadrangular prism,

a pair of terminal installation pieces mounted on the outer surface of the side wall part are arranged on the outer side of the chamfered outer peripheral surface,

the pair of lead portions of the winding are led out to the outside of the side wall portion at a predetermined angle of 20 to 60 degrees, respectively, and are connected to the installation piece.

2. The coil device according to claim 1,

the bottom portion of the middle core portion is fixed to the bottom plate portion of the can core in a state where the coil portion is mounted on the outer periphery of the middle core portion.

3. The coil device according to claim 2,

the bottom of the center core portion is fixed to the bottom plate portion of the tank core by the adhesive.

4. The coil device according to claim 2,

the bottom of the center core portion is fixed to the bottom plate portion of the tank core by a resin containing a magnetic body.

5. The coil device according to claim 1,

the bottom of the center core part is formed integrally with the bottom plate part of the can core.

6. The coil device according to any one of claims 1 to 4,

the upper surface of the installation piece is formed to be at a position approximately in the same plane as the groove bottom surface of the lead groove.

7. The coil device according to claim 6,

the terminal further has:

a terminal body mounted on an outer peripheral surface of the side wall portion;

a lower locking piece formed at a lower end portion of the terminal body and locked to a lower end surface of the side wall portion;

an upper locking piece formed at an upper end portion of the terminal body and locked to an upper end surface of the side wall portion; and

and a connecting piece integrally connecting the installation piece and the terminal main body.

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