JP2014229659A - Inductor and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the molding work of molten resin, and to improve manufacturing efficiency.SOLUTION: An inductor 10 includes: a cylindrical outer core 11 opening at both ends; a coil 18 stored in the inside of the outer core 11; a straight rod-shaped inner core 17 stored in the inside of the outer core 11 while being coaxially inserted in the coil 18, for forming a magnetic path with the outer core 11; a holding member 19 for holding the coil 18 and the inner core 17 to the outer core 11 so as to make axis directions of those orthogonal to an inside surface 11z of the inner core 11; a mold portion 16 filled in the inside of the outer core 11 from one opening portion of the outer core 11, and made from a hardening body of molten resin 15; and a cover member 14 for blocking the other opening portion of the outer core 11 to prevent the leakage of the molten resin 15, and adhered to the mold portion 16 after hardening to remain as a component.

Description

  The present invention relates to an inductor suitably used as a choke coil for boosting a power supply circuit, improving a power factor or current smoothing, and a method for manufacturing the same.

Many reactors and choke coils have already been proposed as electrical components suitable for power circuits such as electric vehicles and hybrid vehicles (see Patent Documents 1 to 5).
Of these, Patent Document 5 includes a rectangular frame-shaped outer core made of a dust core, a bobbin mounted in a frame of the outer core in a state where a coil is wound, and a dust core inserted into the bobbin. There is described a choke coil including a mandrel-shaped inner core and an inner core interposed between the two planes so as to be in a direction perpendicular to two planes facing each other inside the outer core.

In the choke coil of the cited document 5, a mold part for fixing the coil and bobbin is formed inside the outer core by filling the resin between both end faces of the frame using the outer core as a mold frame.
According to the cited document 5, since the choke coil has a simple shape of the outer core and the inner core, it can be easily formed as a dust core, and a choke coil having a simple structure that is neither an ER core nor an EE core is obtained. Since a coil or the like is molded by a mold part formed using a core as a mold, heat dissipation of the coil through the mold part can be realized.

JP 2007-129149 A JP 2009-033051 A JP 2012-039099 A JP 2012-004292 A JP 2013-051402 A

In the choke coil described in Patent Document 5, the molten resin is filled in the entire area of the inner space of the outer core so that the mold part after the molten resin is cured is exposed from the “open” part of the “both” of the outer core. (See FIG. 4 of cited document 5).
Therefore, in order to manufacture the choke coil having the above structure, for example, the open end edge of one of the outer cores is fixed to a flat molding plate so that the molten resin does not leak, and the choke coil is placed inside the outer core. A molding operation of filling the molten resin and waiting for the curing is required.

However, in such a molding operation, after the curing of the molten resin is completed, a step of removing the outer core from the molding plate and a lower surface of the mold part adhered to the molding plate at the time of curing are peeled off from the molding plate. Since a process is required, the operation becomes complicated.
Further, in this case, when the lower surface of the mold part is peeled off from the molding plate, there is a possibility that a part of the cured resin may be chipped.

  In view of such problems, an object of the present invention is to simplify a molding operation of a molten resin and improve manufacturing efficiency in an inductor of a type in which a component housed in an outer core is molded with a molten resin.

  The inductor of the present invention has a pair of opposed inner surfaces, a cylindrical outer core having both ends opened, a coil housed in the outer core, and a magnetic path with the outer core The straight rod-shaped inner core housed inside the outer core while being coaxially inserted into the coil, and the axial direction of the coil and the inner core are perpendicular to the inner surface. The holding member that holds the outer core as described above, the mold portion that is filled from the open portion of the outer core into the outer core, and is formed of a cured resin, and the other of the outer core. A lid member that closes the open portion to prevent the molten resin from leaking, adheres to the cured mold portion, and remains as a component.

  According to the present invention, when manufacturing an inductor of a type in which a component housed in the outer core is molded with a molten resin, the molding operation of the molten resin can be simplified and the manufacturing efficiency can be improved.

It is a perspective view of the inductor which concerns on embodiment of this invention, (a) shows the external appearance in the state where the axial center direction (X direction) of the outer core faced the up-down direction, (b) is the axial center direction of an outer core. The external appearance in a state where (X direction) faces the horizontal direction is shown. It is a perspective view of an inductor concerning an embodiment of the present invention, (a) is an assembly perspective view of an inductor, and (b) is a perspective view of an inductor after assembly and before resin molding. It is an assembly perspective view of the storage assembly with which the inside of the outer core is mounted. (A) is the perspective view which looked at the cover member from the outer surface side, (b) is the perspective view which looked at the cover member from the inner surface side. It is a front view of the inductor which shows the attachment state with respect to a thermal radiation member. It is a circuit diagram which shows an example of the power supply circuit (only main circuit part) mounted in an electric vehicle or a hybrid vehicle for charge of a vehicle-mounted battery.

<Outline of Embodiment of the Present Invention>
Hereinafter, an outline of embodiments of the present invention will be listed and described.
(1) An inductor according to an embodiment of the present invention includes a pair of opposed inner surfaces, a cylindrical outer core having open ends, a coil housed in the outer core, and the outer core. In order to form a magnetic path, a straight rod-shaped inner core housed inside the outer core in a state of being coaxially inserted into the coil, the coil and the inner core, and their axial directions A holding member that holds the outer core so as to be orthogonal to the inner side surface, and a mold part that is filled from the one open part of the outer core into the outer core and is made of a cured resin body. A lid member that closes the other open portion of the outer core to prevent the molten resin from leaking, adheres to the mold portion after curing, and remains as a component.

According to the inductor having the above configuration, the lid member closes the other open portion of the outer core to prevent leakage of the molten resin. Therefore, when the molten resin is filled into the outer core, the lid member is It functions as the bottom plate of the mold consisting of the outer core.
And since the lid member adheres to the mold part after curing and remains as a component, the process of removing the outer core from the aforementioned “molding plate” or the lower surface of the mold part is peeled off from the “molding plate”. A process becomes unnecessary and the molding operation of molten resin becomes easy.

Further, since the process of peeling the lower surface of the mold part from the “molding plate” is not required, there is no possibility that a part of the mold part, which is a cured body of the molten resin, will be chipped, and a decrease in product yield can be prevented.
As described above, according to the inductor having the above-described configuration, after filling with the molten resin, the product can be completed only by waiting for its curing, and the product yield can be prevented from being lowered. Increase efficiency.

(2) In the inductor according to the embodiment of the present invention, it is preferable that an attachment part for attaching the outer surface of the outer core to a heat dissipation member is formed on the holding member and the lid member.
If this attachment portion is used, the outer surface of the inductor can be brought into contact with the heat radiating member for attachment. For this reason, the heat generated from the coil can be dissipated through the heat path of the coil → the mold part → the side wall of the outer core → the heat radiating member, and the temperature rise of the inductor can be reliably prevented.

  Further, if the mounting portion is formed on the holding member and the lid member, a mounting band made of a leaf spring or the like for mounting the outer core to the heat radiating member (for example, the mounting tool 21 in FIG. 8 of Patent Document 5) is separately prepared. There is also an advantage that the number of parts for attaching the inductor can be reduced.

(3) In the inductor according to the embodiment of the present invention, a pair of sandwiching portions that sandwich and hold the coil from the radially outer side are provided so as to protrude from the inner surface of the lid member toward the inner side of the outer core. Is preferred.
In this case, since the pair of sandwiching portions sandwich and hold the coil from the outer diameter side, the insulation between the outer peripheral surface of the coil and the inner surface of the outer core is ensured. Therefore, disturbance of the magnetic path can be prevented. Further, since the pair of sandwiching portions project from the inner surface of the lid member toward the inner side of the outer core, the pair of sandwiching portions adhere to the mold portion after the molten resin is cured. Therefore, the lid member remaining as a component is prevented from dropping off.

(4) In the inductor according to the embodiment of the present invention, the resin material constituting the mold part is preferably made of a resin material having a thermal conductivity of 3 [W / (m · K)] or more. The thermal conductivity is more preferably 5 [W / (m · K)] or more, and further preferably 10 [W / (m · K)] or more.
By using resin materials having these thermal conductivities, it is possible to suppress the heat insulation in the mold part that constitutes the heat path for releasing the heat of the coil as much as possible, and to prevent the temperature rise of the inductor more reliably.

(5) In the inductor according to the embodiment of the present invention, the holding member holds only one end portion in the axial center direction of the member in a state where there is a radial interval between the coil and the inner core. It is preferable to have a part.
In this case, since the holding portion holds only one end portion in the axial direction of the coil and the inner core, the other axial end portion of these members can be disposed close to the inner side surface of the outer core. Therefore, the distance between the inner side surfaces of the outer core can be reduced, and the outer core can be made compact.

(6) However, if only one end in the axial direction is held for the coil, the other end in the axial direction of the coil is the outer core due to the flow pressure received from the resin when the molten resin is filled. The insulation performance between the coil and the outer core can be deteriorated.
Therefore, as the coil, a coil having an inflexible winding end extending from one open portion of the outer core to the outside of the frame is adopted, and the winding end and the open end edge of the outer core are used. It is preferable to further provide a positioning member for positioning the other end in the axial direction of the coil away from the inner side surface of the outer core.

In this case, the positioning member positions the other axial end of the coil away from the inner side surface of the outer core, so that the other axial end of the coil does not contact the outer core and the coil and the outer core are insulated. Performance is improved.
In addition, the above-mentioned “non-flexibility” means that the coil does not bend by its own weight or the flow pressure of the molten resin, and does not limit the fact that it is a substantially perfect rigid body. .

(7) In the inductor having the mounting portion described above, it is preferable that the mounting portion has a contact surface with respect to the heat dissipation member, and the contact surface is flush with an outer surface of the outer core.
In this way, when the contact surface of the mounting portion is configured to be flush with the outer surface of the outer core, when the mounted surface formed on the inductor mounting target (for example, the heat dissipation member) is a flat surface, There is an advantage that it becomes easy to attach to.

(8) The inductor manufacturing method according to the embodiment of the present invention includes the following steps (a) to (d).
(A) First step of assembling a storage assembly by connecting the two with a holding member in a state where the inner core is inserted into the inside of the coil. (B) Both ends are opened, having a pair of inner surfaces facing each other. A second step of housing the housing assembly inside a cylindrical outer core and holding the coil and the inner core by the holding member so that their axial directions are orthogonal to the inner side surface.

(C) A third step of closing the lower open portion of the outer core with a lid member so that the molten resin does not leak. (D) The molten resin from the upper open portion of the outer core into the outer core. 4th process which waits for hardening, fills the mold part which is the hardening body, and leaves the cover member as a component in the above-mentioned manufacturing method. In the above-mentioned manufacturing method, the order of the 2nd process and the 3rd process is changed. Also good.

  According to the above manufacturing method, the lower open portion of the outer core is closed with the lid member so that the molten resin does not leak (third step), and the upper open portion of the outer core is inserted into the outer core. Filling the molten resin, waiting for curing, and leaving the lid member fixed to the mold part, which is the cured body, as a component (fourth step), the step of removing the outer core from the aforementioned “molding plate”, The process of peeling the lower surface of the mold part from the “molding plate” is not necessary. Therefore, the molding operation of the molten resin is facilitated.

Further, since the process of peeling the lower surface of the mold part from the “molding plate” is not required, there is no possibility that a part of the cured resin is chipped to perform the process, and the product yield can be prevented from being lowered.
As described above, according to the manufacturing method including the above steps, after filling the molten resin, the product can be completed only by waiting for the curing, and the decrease in the product yield can be prevented, so that the molding operation of the molten resin can be simplified. And improvement of manufacturing efficiency can be realized.

<Details of Embodiment of the Present Invention>
Hereinafter, the details of the inductor 10 according to the embodiment of the present invention will be described with reference to the drawings.

[Circuit example using inductor]
First, typical applications of the inductor 10 according to the present embodiment will be described.
FIG. 6 shows an example of a power supply circuit (only the main circuit portion is shown) mounted on an electric vehicle (EV) or a plug-in type hybrid vehicle (HEV: Hybrid Electric Vehicle) for charging an in-vehicle battery. FIG.
The inductor 10 according to the present embodiment can be employed in, for example, the choke coils 110A, 110B, and 110C in the power supply circuit of FIG.

The power supply circuit of FIG. 6 is a power supply circuit for charging a vehicle-mounted battery 130 (for example, DC340V) with a commercial power supply 120 (AC100V or 200V), and includes a rectifier / boost circuit 140, a transformer / insulator circuit 150, and a rectifier / smoother. The circuit 160 is configured.
The rectifying / boosting circuit 140 includes a pair of choke coils 110A and 110B, diodes 141 and 142, switching elements 143 and 144, diodes 145 and 146 connected in antiparallel thereto, and a smoothing capacitor 147. .

The transformer / insulation circuit 150 includes four switching elements 151 to 154 and a transformer 150T. The rectifying / smoothing circuit 160 includes four diodes 161 to 164, a choke coil 110 </ b> C, and a smoothing capacitor 165.
The transformer / insulator circuit 150 and the rectifier / smoothing circuit 160 constitute a full-bridge converter that performs DC-DC conversion.

According to the power supply circuit as described above, the AC voltage of the commercial power supply 120 becomes a DC voltage boosted by the rectification / boost circuit 140. Choke coils 110A and 110B contribute to boosting and power factor improvement.
The boosted DC voltage is smoothed by the smoothing capacitor 147 and output. The output DC voltage (for example, about 400 V) is converted into a DC voltage suitable for charging the in-vehicle battery 130 by the full bridge converter configured by the transformer / insulator circuit 150 and the rectifier / smoothing circuit 160. The choke coil 110C contributes to current smoothing.

[Overall structure of inductor]
1 and 2 are perspective views of an inductor 10 according to an embodiment of the present invention. FIG. 3 is an assembly perspective view of the storage assembly 12 mounted inside the outer core 11.
More specifically, FIG. 1A shows an appearance in a state where the axial center direction (X direction) of the outer core 11 faces the vertical direction, and FIG. 1B shows the axial direction of the outer core 11. Shows the appearance of when facing horizontally.

2A is an assembled perspective view of the inductor 10, and FIG. 2B is a perspective view of the inductor 10 after assembly and before resin molding.
2B is a perspective view when it is assumed that the outer core 11 is transparent, in order to illustrate the internal structure of the outer core 11 in an easy-to-understand manner.

In the description of the present embodiment, in order to clarify the direction of the component parts of the inductor 10, terms in the X to Z directions defined below may be used.
X direction: axial center direction of outer core 11 (cylinder axis direction)
Y direction: cross-sectional width direction of outer core 11 Z direction; cross-sectional height direction of outer core 11 (same as the axial direction of the coil)

The inductor 10 of this embodiment is a type in which a component (storage assembly 12) stored inside the outer core 11 is molded with a molten resin 15, and includes an outer core 11, a storage assembly 12, a positioning member 13, a lid, and the like. The member 14 and a mold part 16 that is a cured body of the molten resin 15 (see FIG. 2) are provided as main components.
As shown in FIG. 3, the storage assembly 12 of this embodiment includes an inner core 17, a coil 18, and a holding member 19.

[Outer core and inner core]
The outer core 11 is made of a cylindrical member made of a dust core (a dust core) and having both ends in the X direction open. The outer core 11 is formed in a rectangular tube shape having a cross section whose length in the Y direction is larger than the length in the Z direction, and the end surface 11a, 11b on both sides in the axial direction is formed in a substantially rectangular shape as a whole. Yes.

For this reason, the inside of the outer core 11 is composed of inner surfaces 11y, 11y each having a normal vector in the Y direction and made of planes facing each other, and a pair of planes facing each other having a normal vector in the Z direction. Inner side surfaces 11z and 11z are formed.
Strictly speaking, arc-shaped rounds necessary for molding are formed at the four corners of the inner periphery and outer periphery of the outer core 11, and the detailed structure such as this round is "square cylindrical". Shall not be disturbed.

The inner core 17 is a member for forming a magnetic path together with the outer core 11, and is made of a dust core (a dust core) like the outer core 11. The inner core 17 is made of a straight bar member having a circular cross section.
The dust core is manufactured by subjecting a raw material containing pulverized soft magnetic powder, an insulating coating covering the surface thereof, and a binder to compression molding and heat treatment. As the soft magnetic powder, pure iron (Fe), Fe-Si alloy containing iron, or Fe-Si-Al alloy is suitable. Furthermore, an Fe-Si-B alloy system (amorphous dust core) can also be used.

Specifically, the soft magnetic powder contains about 9.5% by weight of silicon (Si) and about 5.5% by weight of aluminum (Al) in addition to the main component of iron (Fe). The insulating film covering the soft magnetic powder is obtained by thermosetting a silicon resin.
The binder is an acrylic resin. The average particle size of the soft magnetic powder is preferably 30 μm or more and 500 μm or less, and in this embodiment, it is about 150 μm. By setting the average particle size, the magnetic anisotropy is reduced and the core material of the inductor 10 is suitable.

The pressing is preferably performed at room temperature and a pressure of 10 (t / cm ² ). Moreover, it is preferable to heat-process for 1 hour at 750 degreeC in nitrogen atmosphere after shaping | molding.
That is, the main manufacturing process of the dust core consists of 1) a process in which a soft magnetic powder is coated with an insulating film and then a binder is mixed, 2) a pressing process, and 3) a heat treatment process. In addition, the manufacturing process of an amorphous ribbon requires at least 5 processes of cold rolling, lamination | stacking / winding, adhesion | attachment (heating, pressurization), cutting, and heat processing. That is, the dust core has fewer manufacturing steps than the amorphous ribbon.

Moreover, since the magnetic flux easily passes along the plane of the ribbon, the amorphous ribbon is likely to exhibit strong magnetic anisotropy.
For this reason, in the inductor 10 of the present embodiment, if the outer core 11 and the inner core 17 are amorphous ribbons, an eddy current is generated in the outer core 11 facing the end face of the inner core 17 and the current loss increases. . On the other hand, in the case of the dust core of the present embodiment with little anisotropy, eddy currents are not easily generated.

〔coil〕
The coil 18 is formed of a cylindrical member in which one continuous winding 18w is spirally wound. As the winding 18w, a coated wire in which an outer periphery of a conductor made of a conductive material such as copper, aluminum, or an alloy thereof is coated with an insulating coating made of an insulating material can be suitably used.
The conductor can have various shapes such as a rectangular wire having a rectangular cross-sectional shape, a round wire having a circular shape, and a deformed wire having a polygonal shape.

The insulating material constituting the insulating coating is typically an enamel material such as polyamideimide. The thickness of the insulating coating is preferably 20 μm or more and 100 μm or less, and the thicker the pinholes can be reduced, the higher the insulation.
For example, when an enamel material is applied in multiple layers to form an insulating coating, the thickness of the insulating coating can be increased. The insulating coating can also be a multilayer structure made of different materials. For example, a multilayer structure having a polyphenylene sulfide layer on the outer periphery of the polyamideimide layer can be mentioned.

Multi-layer insulation coatings are also excellent in electrical insulation. The number of turns (number of turns) can be selected as appropriate, but as illustrated in FIG. 3, the coil 18 of the present embodiment has approximately four turns.
Further, the coil 18 shown in the figure is made of a rectangular wire (aspect ratio: width / thickness is 5 or more, preferably 10 or more) whose conductor is made of copper and whose winding 18w has a rectangular cross section. An “edgewise coil” formed by edgewise winding a coated rectangular wire made of enamel is employed.

On one side in the axial direction of the coil 18, an extending portion 18 a extending upward from the spiral portion of the coil 18 and a winding end portion 18 b that is bent at a right angle from the extending portion 18 a and extends to the other axial direction are formed. Yes.
Further, on the other side in the axial direction of the coil 18, an extending portion 18 c that protrudes upward from the spiral portion of the coil 18 and a winding end portion 18 d that is bent at a right angle from the extending portion 18 c and extends to the other side in the axial direction. Is formed.

The pair of left and right winding ends 18b, 18d extend straight toward the other side in the axial direction (Z direction) of the coil 18 in a state of being parallel to each other.
The winding 18w of the coil 18 itself has the above-mentioned “inflexibility”, that is, a rigidity that does not bend by the weight of the coil 18 or the flow pressure of the molten resin 15. Accordingly, the pair of left and right winding ends 18b and 18d themselves are inflexible.

[Storage assembly]
The storage assembly 12 includes a holding member 19 that holds one end of the members 17 and 18 in the axial direction (Z direction) in a state where the inner core 17 is inserted coaxially into the coil 18.
The holding member 19 is configured by appropriately joining, for example, an integrally molded product made of PBT (polybutylene terephthalate) or several molded products made of the material.

As shown in FIG. 3, the holding member 19 includes a square plate-like spacer portion 19p, a holding portion 19q extending in the axial direction (Z direction) of the coil 18 from the inner surface of the spacer portion 19p, and an upper end portion of the spacer portion 19p. And projecting portions 19r and 19s projecting outward in the left-right direction (Y direction).
The spacer portion 19p has a width dimension smaller than the inner hollow cross-sectional width of the outer core 11 (the distance between the inner side surfaces 11y and 11y) and a height dimension smaller than the axial direction (X direction) length of the outer core 11. Is formed.

A fitting recess 19t into which the extending portion 18a on one side in the axial center direction of the coil 18 is fitted is formed at the upper end edge of the spacer portion 19p.
The holding portion 19q is formed of a cylindrical body that extends in the axial direction (Z direction) of the coil 18 and is orthogonal to the inner surface of the spacer portion 19p (the surface facing the inner side when housed in the outer core 11). The length of the cylindrical body in the axial direction (Z direction) is shorter than the length of the inner core 17 and the coil 18 in the same direction, and is approximately half or less of them.

The outer diameter of the holding portion 19q is substantially equal to the inner diameter of the coil 18, and the inner diameter of the holding portion 19q is substantially equal to the outer diameter of the inner core 17.
Accordingly, when one end of the coil 18 in the axial direction (Z direction) is fitted into the outer peripheral surface of the holding portion 19q, and one end of the inner core 17 in the axial direction (Z direction) is fitted into the holding portion 19q, In a state where the inner core 17 is inserted into the coil 18, both are held in a cantilever manner with respect to the holding member 19.

When both the members 17 and 18 are fitted into the holding portion 19q as described above, a distance equal to the thickness of the peripheral wall portion constituting the holding portion 19q is formed between the inner peripheral surface of the coil 18 and the outer peripheral surface of the inner core 17. Is secured.
In this embodiment, when connecting the axial direction one end part of the coil 18 to the holding | maintenance part 19q, the extending | stretching part 18a of the coil 18 is engage | inserted by the fitting recessed part 19t. As a result, the circumferential position around the axis of the coil 18 relative to the holding member 19 is positioned.

The protrusions 19r and 19s protrude to the extent that they do not fit within the inner space dimension (distance between the inner side surfaces 11y and 11y) in the cross-sectional width direction (Y direction) of the outer core 11, and the cylindrical direction (X (Position) has a positioning function that defines the storage depth.
Accordingly, when the storage assembly 12 is loaded from the open portion above the outer core 11 with the axial direction of the storage assembly 12 directed in the Z direction, the projecting portions 19r and 19s abut against the edge surface 11a of the outer core 11. At this point, the storage depth in the cylinder axis direction (X direction) is determined.

When the storage assembly 12 is stored in the outer core 11 up to this storage depth, the inner core 17 and the coil 18 have the axial direction (Z direction) orthogonal to the inner side surfaces 11z and 11z. Retained inside.
In the above-mentioned storage state, the axial centers of the inner core 17 and the coil 18 substantially coincide with the center points of the inner side surfaces 11z and 11z.

The storage length Lz in the Z direction of the storage assembly 12 (the length from the outer surface of the spacer portion 19p to the front end surface 17b of the inner core 17 after the assembly of the inner core 17 and the coil 18 to the holding member 19 is completed: FIG. Is substantially the same as the interval between the inner side surfaces 11z, 11z of the outer core 11.
Therefore, the storage assembly 12 is stored almost tightly inside the outer core 11 in the cross-sectional height direction (Z direction) of the outer core 11.

In the above-described storage state, a gap corresponding to the thickness of the spacer portion 19p is formed between the base end surface 17a of the inner core 17 and one inner side surface 11z of the outer core 11, and the distal end surface 17b of the inner core 17 is formed. Directly contacts the other inner surface 11z (see FIG. 5).
Therefore, in this embodiment, the magnetic gap between the axial end surface of the inner core 17 and the inner side surface 11z of the outer core 11 is set to a predetermined value by the thickness of the spacer portion 19p of the holding member 19. The

One of the protrusions 19r and 19s also serves as an attachment part for attaching the outer surface of the outer core 11 to the heat dissipation member (see FIG. 5).
The projecting portion 19r also serving as the mounting portion (hereinafter, also referred to as “mounting portion 19r”) is a screw that penetrates in the Z direction and includes a boss portion that bulges in the X direction and the Y direction from the upper end corner portion of the spacer portion 19p. Has an insertion hole. Further, the contact surface 19r1 of the mounting portion 19r with respect to the heat dissipation member 30 is flush with the outer surface of the outer core 11.

In addition, as a method of connecting the axial direction one end part of the inner core 17 and the coil 18 to the holding part 19q, a physical connection such as “tight fit” may be used, but the connection is uncertain due to a dimensional error. In some cases, it is preferable to use an adhesive.
Further, in order to more reliably fix the storage assembly 12 to the outer core 11, it is possible to apply an adhesive to appropriate positions of the spacer portion 19 p and the projecting portions 19 r and 19 s of the holding member 19 to adhere to the outer core 11. preferable.

(Cover member)
FIG. 4 is a perspective view showing the appearance of the lid member 14. Specifically, FIG. 4A is a perspective view of the lid member 14 viewed from the outer surface side, and FIG. 4B is a perspective view of the lid member 14 viewed from the inner surface side.
The lid member 14 is configured by appropriately joining, for example, an integrally molded product made of PBT (polybutylene terephthalate) or several molded products made of the material.

2 and 4, the lid member 14 includes a rectangular plate-like lid body 14p, a seal rib 14q protruding from the inner surface of the lid body 14p, and a pair of left and right clamping portions 14r that hold the coil 18 therebetween. , 14r and a mounting portion 14s for mounting the inductor 10.
The lid main body 14p is made of a rectangular plate member that substantially fits the end edge surfaces 11a and 11b of the outer core 11, and has a square relief recess 14t on the inner surface side. The escape recess 14t is a recess for spreading the molten resin 15 between the coil 18 and the lid body 14p.

The seal rib 14q is formed in a rectangular frame shape that is slightly smaller than the outer peripheral shape of the lid main body 14p and conforms to the inner hollow section of the outer core 11.
Therefore, when the sealing rib 14q is fitted into the opening end (the inner peripheral edge of the end edge surface 11b) of the outer core 11 in the cylinder axis direction and the open portion of the outer core 11 is closed by the lid member 14, the lid member 14 is moved to the outer core 11. Form the bottom plate.

At this time, since the seal rib 14q is in close contact with the inner side surfaces 11y and 11z of the outer core 11, the open portion of the outer core 11 is sealed so that the molten resin 15 does not leak.
If the dimensional error between the inner shape of the outer core 11 and the outer peripheral shape of the seal rib 14q is small, the open portion of the outer core 11 can be sealed only by physical coupling such as “tight fit”. Since the sealing may be uncertain, it is preferable to bond the lid member 14 to the outer core 11 using an adhesive.

The pair of sandwiching portions 14r, 14r is a plate piece projecting from the inner surface of the lid main body 14p toward the inner side of the outer core 11, and by partially extending the protruding height of the seal rib 14q, the outer core 11 extends in the axial direction (X direction).
Each clamping part 14r, 14r is respectively arranged in the inner surface of the lid main body 14p at a position apart from the central part of the outer core 11 in the sectional height direction (Z direction) and in the sectional width direction (Y direction). The interval in the cross-sectional width direction is the same as or slightly smaller than the diameter of the coil 18.

Accordingly, when both the lid member 14 and the storage assembly 12 are attached to the outer core 11, as shown in FIG. 2B, the coil 18 is sandwiched and held by the pair of sandwiching portions 14r and 14r from the outside of the diameter.
The attachment portion 14s is formed of a boss portion that protrudes integrally from a corner portion on the outer surface of the lid main body 14p, and has a screw insertion hole that penetrates in the Z direction. Further, the contact surface 14 s 1 of the mounting portion 14 s with respect to the heat dissipation member 30 is flush with the outer surface of the outer core 11.

  In the present embodiment, the holding member 19 and the lid member 14 are each provided with one mounting portion 19r, 14s, but the number and structure of the mounting portions provided on each member 19, 14 are limited to those shown in the figure. Instead, two or more attachment portions may be provided.

[Positioning member]
The positioning member 13 is made of a rod-like member shorter than the cross-sectional width dimension of the outer core 11, and for example, an integrally molded product made of PBT (polybutylene terephthalate), or several molded products of the material are appropriately joined. It is constituted by.
As shown in FIG. 2, the positioning member 13 is a spacer interposed between the pair of winding end portions 18 b and 18 d and the edge surface 11 a of the outer core 11 when the storage assembly 12 is stored in the outer core 11. Used as.

The positioning member 13 is interposed between the pair of winding end portions 18b, 18d and the open end edge of the outer core 11, so that the other end portion of the coil 18 in the axial direction (Z direction) is more than necessary. It is prevented from entering deeply into the outer core 11, and the other axial end portion of the coil 18 is positioned away from the inner side surface of the outer core 11.
Therefore, the positioning member 13 may be removed after the molten resin 15 is cured and excluded from the components of the inductor 10.

On the lower surface side of the positioning member 13, a rectangular groove 13 a extending in the Y direction that fits the inner angle of the end edge surface 11 a of the outer core 11 is formed. Accordingly, the positioning member 13 is fixed to the edge surface 11a of the outer core 11 by applying an adhesive to the square groove 13a and sticking it to the inner corner of the edge surface 11a.
Further, on the upper surface side of the positioning member 13, a groove portion 13b into which a bent portion of the winding end portion 18d is fitted is formed.

[Molten resin and mold part]
The molten resin 15 is made of a potting agent made of urethane resin, epoxy resin, silicon resin, or the like. The molten resin 15 is filled inside from the open portion of the outer core 11 where the storage assembly 12 and the lid member 14 are completely attached, and the cured body of the filled molten resin 15 becomes the mold portion 16. Accordingly, the inner core 17, the coil 18, and the holding member 19 constituting the storage assembly 12 are resin-molded while maintaining the positional relationship at the time of mounting, and are fixed by the molding unit 16.

As described above, the molten resin 15 is made of a potting agent for molding a component housed in the outer core 11, and becomes a mold portion 16 after curing to firmly fix the cores 11, 17 and the coil 18 to each other. .
Moreover, if a potting agent is filled so that it may spread over the internal space of the outer core 11, an air layer will be lost around the winding 18w of the coil 18, and the fall of heat dissipation by the presence of the air layer can be suppressed.

Thus, since the mold part 16 after curing functions as a heat path for releasing heat generated from the coil 18 to the outside, it is desirable that the resin material for forming the mold part 16 has as high a thermal conductivity as possible.
For example, the resin material constituting the mold part 16 is preferably made of a resin material having a thermal conductivity of 3 [W / (m · K)] or more. The thermal conductivity is more preferably 5 [W / (m · K)] or more, and further preferably 10 [W / (m · K)] or more.

[Inductor manufacturing method]
The inductor 10 of the present embodiment can be manufactured, for example, by performing the following first to fourth steps.
(First step)
As shown in FIG. 3, both end portions of the inner core 17 and the coil 18 in the axial center direction (Z direction) are fitted into the holding portions 19 q so that the inner core 17 is inserted into the coil 18. 17 and 18 are coupled to the holding member 19. Thereby, the storage assembly 12 is assembled.

(Second step)
Next, as shown in FIG. 2A, the assembled storage assembly 12 is stored inside the outer core 11 from one open portion of the cylindrical outer core 11 whose both ends are open. This storage is performed until the projecting portions 19r and 19s of the holding member 19 come into contact with the end surface 11a of the outer core 11. In addition, the positioning member 13 is interposed between the winding end portions 18 b and 18 d of the coil 18 and the end edge surface 11 a of the outer core 11 during the storage.

  When the above storage is completed, the coil 18 and the inner core 17 of the storage assembly 12 are held by the holding member 19 so that the axial direction (Z direction) thereof is orthogonal to the inner side surfaces 11z and 11z of the outer core 11. Is done.

(Third step)
Next, the other open portion of the outer core 11 is closed with a lid member 14 so that the molten resin 15 does not leak. Specifically, the seal rib 14q of the lid member 14 is fitted into the inner peripheral side of the end edge surface 11b of the outer core 11, and the lid member 14 is used as the bottom plate of the outer core 11.
At this time, the pair of sandwiching portions 14r and 14r projecting from the inner surface side of the lid member 14 sandwich the coil 18 from the radially outward direction and position the outer core 11 in the cross-sectional width direction (Y direction).

  Note that the order of the second step and the third step may be interchanged. That is, the storage assembly 12 may be mounted inside the outer core 11 after the outer core 11 is first closed by the lid member 14.

(4th process)
And as shown in FIG.2 (b), the molten resin 15 is filled into the inside of the said outer core 11 from the open part of the upper side of the outer core 11. As shown in FIG. The filling of the molten resin 15 is performed until the end surface 11a of the outer core 11 is reached.
Thereafter, the molten resin 15 is awaited to be cured, and the inductor member 10 is completed as a product by leaving the lid member 14 fixed to the mold part 16 as a cured body as a component.

[Inductor mounting state]
FIG. 5 is a front view of the inductor 10 showing a state of attachment to the heat radiating member 30.
Here, the heat radiating member 30 refers to a member that can absorb heat and carry it out, such as a water jacket. In FIG. 5, the left part of the center line indicated by the alternate long and short dash line is a front view excluding the mold part 16 for easy understanding of the internal structure, and the right part of the center line is a front sectional view. ing.

As shown in FIG. 5, in the inductor 10 of the present embodiment, the inductor 10 is attached to the attached surface 30 a of the heat radiating member 30 by using the attaching portion 19 r provided on the holding member 19 and the attaching portion 14 s provided on the lid member 14. Is screwed.
That is, the outer surface of the outer core 11 and the contact surfaces 19r1, 14s1 of the mounting portions 19r, 14s flush with the outer surface are installed on the mounted surface 30a of the heat radiating member 30, and in this state, the screws of the mounting portions 19r, 14s The inductor 10 is attached to the heat dissipation member 30 by screwing the mounting screw 31 inserted through the insertion hole into the heat dissipation member 30.

If the outer surface of the outer core 11 is attached to the heat radiating member 30 in this manner, heat generated from the coil 18 is radiated through the heat path of the coil 18 → mold portion 16 → side wall of the outer core 11 → heat radiating member 30. And the temperature rise of the inductor 10 can be prevented.
If a metal collar is inserted into the screw insertion holes of the mounting portions 19r and 14s, the mounting portions 19r and 14s, which are resin members, are damaged due to excessive tightening of the mounting screws 31 (bolts and nuts). Can be prevented in advance.

〔effect〕
According to the inductor 10 of the present embodiment, the lid member 14 closes the lower open portion of the outer core 11 to prevent the molten resin 15 from leaking, and when the molten resin 15 is filled inside the outer core 11. Moreover, it functions as a bottom plate of a mold made of the outer core 10.
The lid member 14 is fixed to the cured mold portion 16 and remains as a component, so that the outer core 11 is removed from the “molding plate” or the lower surface of the mold portion 16 is peeled off from the “molding plate”. A process becomes unnecessary and the shaping | molding operation | work of the molten resin 15 becomes easy.

  Further, since the process of peeling the lower surface of the mold part 15 from the “molding plate” is not required, a part of the mold part 16 that is a cured body of the molten resin 15 is not chipped, thereby preventing a decrease in product yield. it can.

The inductor 10 of the present embodiment can be attached by bringing the outer surface of the outer core 11 into contact with the heat radiating member 30, so that the heat generated by the coil 18 can be released to the heat radiating member 30 through a heat path passing through the mold part 16. it can. Therefore, the temperature rise of the inductor 10 can be prevented.
Further, since the mounting portions 19r and 14s are formed on the holding member 19 and the lid member 14, there is no need to separately prepare a mounting band made of a leaf spring or the like for mounting the outer core to the heat radiating member 30. The number of parts for mounting can be reduced.

According to the inductor 10 according to the present embodiment, the pair of holding portions 14r and 14r provided on the lid member 14 hold the coil 18 from the outside of the diameter, so that the outer peripheral surface of the coil 18 and the inner surface 11y of the outer core 11 are retained. , 11y is reliably insulated.
Further, since the pair of sandwiching portions 14r and 14r project from the inner surface of the lid member 14 toward the inner side of the outer core 11, after the molten resin 15 is cured, the pair of sandwiching portions 14r and 14r are molded portions. The lid member 14 that adheres to the 16 and remains is reliably prevented from falling off.

According to the inductor 10 of the present embodiment, the holding member 19 holds only one end in the axial direction of the members 18 and 19 in a state where there is a radial interval between the coil 18 and the inner core 17. Part 19q.
For this reason, the axial direction other end part of the coil 18 and the inner core 17 can be arrange | positioned adjacent to the inner surface 11z of the outer core 11, and the distance between the inner surfaces 11z of the outer core 11, 11z can be made small. Therefore, the outer core 11 can be made compact.

According to the inductor 10 of the present embodiment, the coil 10 has the non-flexible winding end portions 18b and 18d extending from the open portion on the upper side of the outer core 11 to the outside of the frame.
Then, the positioning member 13 is interposed between the winding end portions 18 b and 18 d and the open end edge (end surface 11 a) of the outer core 11, and the other axial end portion of the coil 18 is connected to the inside of the outer core 11. Since positioning is performed away from the side surface 11z, the other axial end portion of the coil 18 does not contact the outer core 11 when the molten resin 15 is filled. Therefore, the insulation performance between the coil 18 and the outer core 11 is improved.

Further, according to the inductor 10 of the present embodiment, the mounting portions 19r and 14s have the contact surfaces 19r1 and 14s1 with respect to the heat radiating member 30, and the contact surfaces 19r1 and 14s1 are flush with the outer surface of the outer core 11. It has become.
For this reason, when the to-be-attached surface 30a formed in the attachment object (for example, the heat radiating member 30 shown in FIG. 6) of the inductor 10 is a plane, it becomes easy to attach to the plane.

[Modification]
In the above-described embodiment, the outer core 11 has a rectangular cross section on the inner side surface and the outer side surface. However, the outer side surface does not necessarily have to be a square shape, and may have a shape inflated in an arc shape. Good.
Moreover, the inner hollow cross section of the outer core 11 should just have at least a pair of opposing inner side surfaces 11z and 11z, and other surfaces may be curved.

In the above-described embodiment, the inner core 17 is composed of an integral dust core, but may be a segmented type inner core in which spacers are sandwiched between a plurality of blocks that are segmented in the axial direction. .
In the above embodiment, the inductor for the on-vehicle battery charging power supply circuit has been described. However, the driving battery voltage (200 V to 300 V, etc.) is set to 14 V for driving an auxiliary machine of an electric vehicle or a hybrid vehicle. It may be used for a power supply circuit that steps down the voltage.
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 10: Inductor 11: Outer core 11a, 11b: End surface 11y, 11z: Inner side surface 12: Storage assembly 13: Positioning member 13a: Square groove 13b: Groove part 14: Lid member 14p: Lid body 14q: Seal rib 14r, 14r: Clamping portion 14s: Mounting portion 14t: Escape recess 14s1: Contact surface 15: Molten resin 16: Molded portion 17: Inner core 17a: Base end surface 17b: Tip end surface 18: Coil 18w: Winding 18a: Extending portion 18b: Winding End portion 18c: Extension portion 18d: Winding end portion 19: Holding member 19p: Spacer portion 19q: Holding portion 19r: Protruding portion (attachment portion)
19s: Protruding portion 19t: Fitting recess 19r1: Contact surface 30: Heat radiating member 30a: Mounted surface 31: Mounting screw 110A, 110B, 110C: Choke coil 120: Commercial power supply 130: In-vehicle battery 140: Boost circuit 141, 142 : Diode 143, 144: Switching element 145, 146: Diode 147: Smoothing capacitor 150: Insulation circuit 150T: Transformer 151-154: Switching element 160: Smoothing circuit 161-164: Diode 165: Smoothing capacitor

Claims (8)

A cylindrical outer core having a pair of opposed inner surfaces and having both ends open;
A coil housed inside the outer core;
To form a magnetic path with the outer core, a straight rod-shaped inner core housed inside the outer core in a state of being coaxially inserted into the coil;
A holding member that holds the coil and the inner core with respect to the outer core such that the axial direction thereof is orthogonal to the inner surface;
A mold part made of a cured body of molten resin, filled in the outer core from one open part of the outer core,
An inductor comprising: a lid member that closes the other open portion of the outer core to prevent leakage of the molten resin, and is fixed to the cured mold portion and remains as a component.   The inductor according to claim 1, wherein an attachment portion for attaching the outer surface of the outer core to a heat dissipation member is formed on the holding member and the lid member.   3. The inductor according to claim 1, wherein a pair of sandwiching portions that sandwich and hold the coil from the outside of the diameter are projected from an inner surface of the lid member toward an inner side of the outer core.   The inductor according to any one of claims 1 to 3, wherein the resin material constituting the mold part is made of a resin material having a thermal conductivity of 3 [W / (m · K)] or more.   The said holding member has a holding | maintenance part which hold | maintains only the axial direction one end part of these members in the state with a radial direction space | interval between the said coil and the said inner core. The inductor according to item 1. The coil has a non-flexible winding end that extends out of the frame from one open portion of the outer core,
A positioning member that is positioned between the winding end and the open end edge of the outer core to position the other end in the axial direction of the coil away from the inner side surface of the outer core; The inductor according to any one of claims 1 to 5.   The inductor according to claim 2, wherein the attachment portion has a contact surface with respect to the heat radiating member, and the contact surface is flush with an outer surface of the outer core. An inductor manufacturing method including the following steps (a) to (d).
(A) First step of assembling a storage assembly by connecting the two with a holding member in a state where the inner core is inserted into the inside of the coil. (B) Both ends are opened, having a pair of inner surfaces facing each other. A second step (c) in which the housing assembly is housed in a cylindrical outer core, and the coil and the inner core are held by the holding member so that their axial directions are orthogonal to the inner side surface. The third step of closing the lower open portion of the outer core with a lid member so that the molten resin does not leak (d) The molten resin is filled into the outer core from the upper open portion of the outer core. 4th process of waiting for hardening and leaving the said cover member fixed to the mold part which is the hardening body as a component

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