JP5556285B2 - Reactor - Google Patents

Description

  The present invention relates to a reactor in which a coil is formed by winding a rectangular wire with an insulating coating inside a core containing soft magnetic powder.

2. Description of the Related Art Reactors as inductance components that incorporate a coil formed by winding a conductor wire with an insulating coating inside a core have been used in various fields.
For example, in a hybrid vehicle, a fuel cell vehicle, an electric vehicle, and the like, a booster circuit is provided between a battery and an inverter that supplies AC power to a motor (electric motor), and a reactor (choke) that is an inductance component is provided in the booster circuit. Coil).
For example, in a hybrid vehicle, the voltage of the battery is about 300 V at the maximum, while it is necessary to apply a high voltage of about 600 V to the motor so as to obtain a large output. For this purpose, a reactor is used as a component for a booster circuit.
This reactor is also widely used for boosting circuits of photovoltaic power generation and others.

Conventionally, a coil in which a wire having a round cross section is wound has been generally used as the coil of such a reactor.
However, in the case of a coil wound with such a wire having a round cross section, a large gap is generated between adjacent wires.
The cross-sectional area of the wire requires a predetermined cross-sectional area according to the current flowing therethrough, and the number of turns is determined in order to obtain a desired inductance.
As a result, the height of the entire coil is increased, and accordingly, the height of the core is also increased and the reactor is enlarged.

Therefore, in order to reduce the size of the reactor, as disclosed in, for example, Patent Document 1 below, an edgewise coil formed by winding a flat rectangular wire in the width direction is generally used as a coil.
As shown in FIG. 20, in the case of the edgewise coil 200, adjacent wire rods (flat wire rods) can be brought into close contact with each other, and no useless space is created between the wire rods and the wire rods.
In the figure, reference numeral 204 denotes a core, and 206 denotes a reactor including the edgewise coil 200 and the core 204.
In this type of reactor, in order to increase the inductance L, it is effective to increase the number of turns of the coil.
Here, the inductance L is expressed by the following formula (1).
L∝μ × N ² × A / l (1)
Where μ: permeability of the core N: number of turns of the coil (number of turns)
A: Core magnetic path cross-sectional area l: Core magnetic path length

As can be seen from FIG. 20, in the conventional reactor 206, if the number of turns of the coil 200 is increased, the height of the coil 200 (height in the coil axis direction) is inevitably increased.
Thus, when the height of the coil 200 is increased, the magnetic path length (the length of the magnetic flux indicated by 208 in the figure) is increased, and this is the direction in which the inductance L is decreased.

Therefore, in order to keep the inductance L constant, it is necessary to increase the cross-sectional area of the magnetic path of the core. As a result, the reactor 206 has a large height dimension and a large radial dimension, and the overall size is increased.
Further, as the reactor becomes larger, the amount of core material required increases.
In the case of the reactor, the ratio of the material cost to the total cost is high, and the cost of the reactor increases as the material cost of the core material increases.
Furthermore, if the reactor becomes larger, the overall loss due to core loss, copper loss (loss due to the coil itself), etc. will also increase.

As a prior art to the present invention, the following Patent Document 2 discloses an invention related to an inductor, in which an air-core coil wound in an alpha winding is housed in a navel pot core and a terminal portion of the navel pot core. By forming a thin-film electrode in the dip method and electrically connecting the end of the coil to it, there is no need for a separate connection terminal, which has been required in the past, and the inductor is miniaturized. The point which was made is disclosed.
The one disclosed in Patent Document 2 is intended to reduce the size of the inductor (reactor), but the one disclosed in Patent Document 2 differs from the present invention in the means for downsizing. It is different.
Further, Patent Document 2 does not mention the aspect ratio in the longitudinal section of the coil.

  Patent Document 3 listed below discloses an inductor in which a similar alpha-wound coil is housed in a pot core. However, Patent Document 3 does not mention the aspect ratio in the longitudinal section of the coil.

  Further, Patent Document 4 below discloses the use of an eyeglass coil in which two edgewise coils are connected horizontally, but this does not have two edgewise coils stacked on the same axis. What is disclosed in Patent Document 4 is different from the present invention.

Further, the following Patent Document 5 discloses an invention about a reactor, in which an edgewise coil is arranged on the inner periphery, and a coil in which a coil (not a flatwise coil) in which a rectangular wire is wound in a spiral shape is arranged outside is disclosed. It is disclosed.
However, the one disclosed in Patent Document 5 is a composite reactor having two functions in one body by sharing the core with two separate reactors, and is not an attempt to reduce the size. This is different from the present invention.

Next, Patent Document 6 discloses an invention relating to a magnetic element, in which the cross section of the wire in the coil is rectangular, and the ratio of the long side dimension of the wire to the short side dimension (aspect ratio) is about 10. It is disclosed that by increasing the resistance, the increase in DC resistance when the number of turns of the coil is increased is suppressed and the equivalent inductance is improved.
5 and FIG. 6 discloses that the first coil and the second coil formed by winding a wire in the thickness direction are stacked in two stages in the vertical direction.
However, the one disclosed in Patent Document 6 is not a coil in which the coil is entirely embedded in a soft magnetic core, and the one disclosed in Patent Document 6 is the coil wire itself. It focuses on the aspect ratio and does not specify the aspect ratio of the cross-sectional shape of the coil itself, and its purpose is different from that of the present invention in that it does not aim at reducing the reactor weight or loss. Is.

JP 2008-182151 A JP 2007-305665 A JP 2007-96181 A JP 2008-192649 A JP 2006-310550 A JP 2002-43140 A

  The present invention has been made for the purpose of providing a reactor capable of reducing the overall cost by reducing the size and weight of the entire reactor while keeping the inductance high, and reducing the loss while keeping the inductance high. It is.

Thus, according to the first aspect of the present invention, there is provided a reactor in which a coil formed by winding a rectangular wire with an insulating coating inside a core containing soft magnetic powder is embedded in a state of being entirely wrapped by the core, In a form in which a plurality of coil blocks are connected to each other in a coaxial state via an insulating sheet in a height direction and / or radial direction that is a coil axial direction and in a direction orthogonal to the winding direction of the wire rod. The aspect ratio A / B is within the range of 0.7 to 1.8, where A is the height dimension in the longitudinal section of the coil and B is the radial dimension, including the insulating sheet. Thea is, the insulating coatings with a coil, while forming a coil coating member by coating a state entirely enclose the outer by an electric insulating resin containing no soft magnetic powder, said core, said coil coatings The body is buried inside A molded body formed by injection-molding a mixture of the soft magnetic powder and the thermoplastic resin in a state where the resin is coated, and the resin coating layer of the coil coating body is formed of a thermoplastic resin, and the resin The coating layer is formed by joining and integrating a molded body including an outer peripheral coating portion that covers the outer peripheral surface of the coil and a molded body including an inner peripheral coating portion that covers the inner peripheral surface of the coil. And

  According to a second aspect of the present invention, in the first aspect, the coil is a flatwise coil formed by winding a flat wire in the thickness direction of the wire, and the coil blocks are stacked in a plurality of stages in the height direction. And

  A third aspect is characterized in that, in any one of the first and second aspects, the soft magnetic powder is a powder having a composition containing 0.2 to 9.0 mass% of pure Fe or Si.

According to a fourth aspect of the present invention, the core according to any one of the first to third aspects , wherein the core includes a primary molded body including a cylindrical outer peripheral side molded portion in contact with the outer peripheral surface of the coil coated body, and the coil coated body. It is characterized in that a secondary molded body including an inner peripheral side molded portion that is in contact with the inner peripheral surface is joined and integrated at a boundary surface.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the core is injection-molded integrally with a container portion of a reactor case.

A sixth aspect of the present invention is characterized in that, in any one of the first to fifth aspects, the present invention is used in an alternating magnetic field having a frequency of 1 to 50 kHz.

Effects and effects of the invention

  As described above, according to the present invention, a rectangular wire is used as a coil wire, and a plurality of coil blocks are connected to each other in a state of being coaxially stacked in the height direction and / or radial direction that is the coil axis direction. The aspect ratio A / B is configured to be in the range of 0.7 to 1.8 when the height dimension A and the width dimension B in the longitudinal section of the coil are configured.

According to the present invention, it has been confirmed that the reactor can be effectively reduced in size and weight while maintaining high inductance characteristics as will be clarified later, and the loss can be reduced.
This is because when the coil is configured according to the present invention, the magnetic path length can be shortened while maintaining the same cross-sectional area and number of turns of the coil wire material as compared with the conventional reactor shown in FIG. This is an effect brought about as a result of the reduction in the size.

FIG. 12A shows a flatwise coil obtained by winding a flat wire in the thickness direction as an embodiment of the present invention, and two coil blocks 10-1 and 10-2 are arranged in the direction of winding the wire. The coil 10 is formed by stacking two stages coaxially upward and downward in the orthogonal coil axis direction, and the height dimension of the coil 10 (the height dimension of the coil block 10-1 and the coil block 10-2). ) Is represented by A and the aspect ratio A / B in the range of 0.7 to 1.8 when the width dimension is B is schematically shown.
As is clear from comparison with FIG. 20, in the case shown in FIG. 12A, the magnetic path length, which is the length of the magnetic flux 208, can be effectively shortened.

The magnetic path length is an average of the lengths of all lines of magnetic force, but the magnetic path length is shortened as the circumferential length of the longitudinal section of the coil 10 is shortened.
That is, in the reactor of the present invention shown in FIG. 12 (A) as an example, the magnetic path length can be shortened by shortening the circumferential length in the longitudinal section of the coil.

According to the present invention, the reactor can be miniaturized, the weight can be reduced with the miniaturization, the amount of the core material can be reduced, the required cost of the reactor can be reduced, and the loss is accompanied with the miniaturization. Can be effectively reduced.
In the present invention, the aspect ratio represented by A / B is desirably 0.8 to 1.2, and more desirably 0.9 to 1.1.

Further, the present invention covers a coil with an insulating coating so as to be entirely encased from the outside with an electrically insulating resin to form a coil coating, and the resin coating layer of the coil coating is formed with a thermoplastic resin. The resin coating layer is formed by joining a molded body including an outer peripheral coating portion covering the outer peripheral surface of the coil and a molded body including an inner peripheral coating portion covering the inner peripheral surface of the coil. It is.

By configuring the coil covering in this way, it becomes possible to manufacture a reactor including the coil covering as follows.
That is, the resin coating layer of the coil coating is formed by injection molding, and the injection molding step B is performed by bringing the primary molding die for the resin coating layer into contact with the inner peripheral surface or outer peripheral surface of the coil. Resin material in the primary molding cavity of the primary molding die formed on the outer peripheral side or inner peripheral side of the coil in a state where the coil is positioned and restrained in the radial direction on the inner peripheral surface or outer peripheral surface by the primary molding die A step B-1 for forming a primary molded body including the outer peripheral coating portion or the inner peripheral coating portion in the resin coating layer and integrating it with the coil, and then the primary molded body together with the coil with the resin coating layer. The resin material is injected into the secondary molding cavity of the secondary molding die formed on the inner or outer peripheral side of the coil, and the inner peripheral coating portion or outer periphery in the resin coating layer. Forming a secondary molded body including a covering portion, and a coil and 1 The reactor can be manufactured by performing injection molding separately in the process B-2 integrated with the next molded body.

According to this manufacturing method, when the coil covering body is injection-molded, the coil covering body, specifically the resin, is formed in a state where the coil is well positioned and held by the molding die by performing the molding at least twice. The coating layer can be excellently injection molded, and at the time of molding, the coil can be well prevented from being displaced due to injection pressure or fluid pressure, and the resin coating layer can be satisfactorily coiled. It becomes possible to mold.

The reactor of the present invention can be configured as follows.
(About the components of soft magnetic powder)
In the present invention, as the soft magnetic powder, it is desirable to use a powder having a composition containing 0.2 to 9.0% (same as mass% or less) of pure Fe or Si (Claim 3).
Pure Fe has the disadvantage of high core loss, but is inexpensive and easy to handle. In magnetic materials, magnetic flux density is the second highest after permendur. Therefore, when this feature is important, pure Fe powder should be used. Is desirable.

Fe-based soft magnetic alloy powder containing 0.2 to 9.0% of Si has a lower magnetic flux density than pure Fe as Si increases, but the core loss can be reduced, so the balance between both is good and easy to handle Have
In particular, when the Si content is 6.5%, the core loss takes a minimum value and the magnetic flux density is relatively high, so that it becomes an excellent soft magnetic material.
If it exceeds 6.5%, the core loss starts to increase, but it is still practical enough up to 9.0% because the magnetic flux density is high.
However, if it exceeds 9.0%, the magnetic flux density is small and the core loss is large.
On the other hand, if it is less than 0.2%, it has almost the same characteristics as pure Fe.

The Si-containing Fe-based soft magnetic alloy powder containing 6 to 7% Si has a good balance between the inductance characteristics and the heat generation characteristics, and when these are emphasized, the composition contains 6 to 7% Si. It is desirable to use those.
On the other hand, those containing 2 to 3% of Si have a good balance between cost, performance such as inductance characteristics and heat generation characteristics, and when importance is attached to this point, it is desirable to use those containing 2 to 3% of Si.

In the present invention, one or more of Cr, Mn and Ni can be added as optional elements to the soft magnetic powder as required.
However, when Cr is added, the amount added is preferably 5% by mass or less. The reason is that it becomes easier to reduce the core loss.
Mn and Ni are preferably 1% by mass or less in total. The reason is because it becomes easy to maintain a low coercive force.

(About powder)
The soft magnetic powder may be obtained by atomizing by gas spraying, water spraying, centrifugal spraying, combinations thereof (for example, gas / water spraying), cooling immediately after gas spraying, jet mill, stamp mill, ball mill, etc. Powders obtained by mechanical pulverization or chemical reduction can be used.

  From the viewpoints of relatively small distortion, easily spherical shape and excellent dispersibility, and mechanical energy is not required for pulverization, the soft magnetic powder is preferably made by an atomizing method. More preferably, the powder is made by a gas atomization method from the viewpoint of small distortion and little oxidation.

  The particle diameter of the soft magnetic powder is, for example, in the range of 1 to 500 μm from the viewpoint of powder yield during atomization, kneading torque and seizure during kneading, fluidity during injection molding, and frequency used in the magnetic core. The thickness is preferably in the range of 5 to 250 μm, more preferably in the range of 10 to 150 μm.

  Although the powder is more effective in reducing eddy current loss as the particle size becomes smaller, the hysteresis loss tends to increase. Therefore, the upper and lower limits of the particle size of the powder, the distribution of the particle size, and the like may be determined from the balance between the powder yield (ie, cost) and the obtained effect (ie, core loss), the frequency used, and the like.

  The soft magnetic powder may be heat-treated in order to remove strain and increase the size of crystal grains. Examples of the heat treatment conditions include a temperature of 700 ° C. to 1000 ° C., a time of 30 minutes to 10 hours, and the like in an atmosphere of one or both of hydrogen and argon.

  As the organic polymer as a binder constituting the core material together with the soft magnetic powder, various thermoplastic resins, resins such as thermosetting resins, rubbers, thermoplastic elastomers, or combinations thereof can be used. Preferably, a resin can be suitably used from the viewpoints of heat resistance and mechanical strength.

Examples of the resin include polyphenylene sulfide (PPS) resin, polyamide (PA) resin, polyester resin, polyethylene resin, polypropylene resin, epoxy resin (for example, when potting a core).
Of these, polyphenylene sulfide resins and polyamide resins are preferred from the viewpoints of heat resistance, flame retardancy, insulation, moldability, mechanical strength, and the like.

The ratio of the soft magnetic powder in the mixture of the soft magnetic powder and the binder is 30% by volume or more from the viewpoint of increasing the magnetic flux density, setting the magnetic permeability to an appropriate range, increasing the thermal conductivity, and preferably It is good to set it as 50 volume% or more, More preferably, it is 60 volume% or more.
In addition to the soft magnetic powder and the organic polymer, the soft magnetic kneaded material may include various additives such as an antioxidant, an anti-aging agent, an ultraviolet absorber, a filler, a stabilizer, a reinforcing agent, and a colorant as necessary. 1 type, or 2 or more types may be contained.

  The soft magnetic kneaded material is, for example, a soft magnetic powder, an organic polymer such as a powder, and various additives added as necessary at an appropriate ratio, and this is mixed with a biaxial kneader. It can manufacture by passing through processes, such as kneading | mixing various compounds by making an organic polymer into a molten state using kneading machines.

(About molding method)
When the core is injection-molded, a soft magnetic kneaded material in which a soft magnetic powder and an organic polymer are previously kneaded, such as the soft magnetic kneaded material described above, is used in an injection molding apparatus. It is possible to use a method of forming by supplying, plasticizing (melting) this, and injecting it into a mold. In addition, the soft magnetic powder and the powdery organic polymer are supplied individually or in a mixed state to the injection molding device, and the organic polymer is melted in the device so that the soft magnetic powder and the organic polymer It is also possible to produce a soft magnetic kneaded material by kneading the molecules and to inject it into a mold.

If the soft magnetic kneaded material is injected into the mold and then cooled for an appropriate time, an injection-molded core having a predetermined shape corresponding to the cavity shape of the mold can be obtained. Note that the obtained injection-molded core may be subjected to processing such as machining as necessary.
As injection molding devices, horizontal injection molding devices, vertical injection molding devices, plunger injection molding devices, screw injection molding devices, electric injection molding devices, hydraulic injection molding devices, two-material injection molding devices, A combined injection molding machine or the like can be used.

In the present invention, the flatwise coil is divided into three coil blocks 10-1, 10-2, and 10-3 as shown in FIG. State of stacking in three stages, or dividing edgewise coils into two coil blocks 10-1 and 10-2 as shown in FIG. 12C and overlapping them in two rows in the radial direction It is also possible to arrange them.
Alternatively, the entire coil 10 may be configured by arranging more coil blocks in the height direction that is the coil axis direction or in a radial direction.

  However, in the present invention, as shown in FIGS. 12 (A) and 12 (B), a coil block of a flatwise coil formed by winding a rectangular wire in the thickness direction is stacked in a plurality of stages, preferably in two stages. Therefore, it is desirable to constitute the entire coil (claim 2).

Then claim 4, the upper SL core constituted by the molded body formed by injection molding a mixture material of soft magnetic powder and a thermoplastic resin, and the core, a cylindrical shape in contact with the peripheral surface of the coil coating material The primary molded body including the outer peripheral side molded portion and the secondary molded body including the inner peripheral side molded portion in contact with the inner peripheral surface of the coil cover are joined and integrated at the boundary surface.

By configuring the reactor in this way, it can be manufactured as follows.
In other words, the step A for injection molding the core includes a cylindrical outer peripheral side molding portion that is in contact with the outer peripheral surface of the coil covering body, and a shape having an opening for fitting the coil covering body on one end side in the coil axial direction. The primary molded body of step A-1 is pre-injected with a primary mold for the core, and the secondary molded body including the inner peripheral side molded portion in contact with the inner peripheral surface of the coil cover is used for the core. In step A-2, the coil covering is fitted into the outer peripheral side molding portion of the primary molded body obtained in step A-1. And forming the secondary molded body including the inner peripheral side molded portion simultaneously with the secondary molding in the state where the outer peripheral side molded portion is constrained and held in the radial direction from the outer peripheral side by the secondary molding die for the core. A reactor can be manufactured using the method which integrates a body, a primary compact, and a coil covering.

  Conventionally, as a method of manufacturing a reactor, a coil is set in an outer case or container, and a mixture of a thermosetting resin and soft magnetic powder is dispersed in an outer case or container. Injecting and then heating it to a predetermined temperature and curing the resin liquid over a predetermined time, so that the core is molded and at the same time integrated with the coil (casting molding) is generally used (For example, disclosed in Japanese Patent Application Laid-Open Nos. 2007-27185 and 2008-147405).

  However, this manufacturing method requires a large heating furnace for curing the resin liquid containing the soft magnetic powder, and requires a large amount of heat energy for curing. There is a problem that it takes a long time, the cost increases, and it is difficult to increase productivity.

However, according to the manufacturing method by injection molding, it is possible to solve various problems of the manufacturing method by potting molding.
However, when the core is injection molded simply with the coil set inside the injection mold, the following difficult problem arises.

The mixed material of the soft magnetic powder and the thermoplastic resin is in a molten state at a temperature of, for example, 300 ° C. or more when injected into the mold cavity, and is cooled by the mold inside the mold after injection. Solidifies into a molded body.
At that time, or in the process of being taken out from the mold and then cooled to room temperature, the core as the molded body tends to shrink greatly in the radial direction.

However, since the metal coil is located inside the core, the core cannot radially contract on the outer peripheral side of the coil (the coefficient of thermal expansion is large between the core and the metal coil). As a result, the outer peripheral portion of the coil tends to contract in the circumferential direction, and as a result, a crack K occurs in the outer peripheral portion of the core 16 as shown in FIG.
The occurrence of such cracks K in the core 16 is a factor that degrades the performance as a reactor.

  However, when the reactor is configured as shown in claim 4 and is manufactured by the above-described method, the outer peripheral side portion (outer peripheral side molding portion) of the core is previously separated from the coil alone by this manufacturing method. Since it is molded as a next molded body, there is no problem that cracks occur in the outer circumferential side molded portion due to the coil located inside the core during molding.

  Since the primary molded body including the outer peripheral side molded part is preliminarily molded separately from the coil, the primary molded body, specifically, the outer peripheral side molded part can be freely contracted with cooling during the molding. Because.

On the other hand, the secondary molded body including the inner circumferential side molded portion that is in contact with the inner circumferential surface of the coil (strictly, the inner circumferential surface of the coil covering body) is molded integrally with the coil with the coil set in a molding die. However, since the inner peripheral side molded portion is not particularly subjected to resistance by the coil when contracting in the radial direction, there is no particular problem that cracking occurs due to the contraction.
That is, according to said manufacturing method, the problem that a crack generate | occur | produces in a core by presence of a coil can be solved effectively.

  In this manufacturing method, the coil cover is fitted into the outer peripheral side molded portion of the primary molded body obtained in step A-1 in an internally fitted state, and the outer peripheral side molded portion of the primary molded body is used for the core. The secondary molded body including the inner peripheral side molding portion of the core can be molded in a state in which the secondary molding die is restrained and held in the radial direction from the outer peripheral side.

When the secondary molded body of the core is molded in this state, it is possible to prevent the coil from being displaced from the set position by the injection pressure and the fluid pressure during the molding of the secondary molded body, and the coil is accurately positioned at a preset position. The core can be completely molded while being positioned and held.
Accordingly, it is possible to satisfactorily prevent adverse effects on the characteristics of the coil composite molded body due to the displacement of the coil during the molding of the core.

In the present invention, it may have been injection-molded integrally with the container portion and the core of the reactor case when injection molding the core (Claim 5).
In this way, after the core is formed, that is, after the reactor is manufactured, the step of attaching the container portion of the reactor case to the core of the reactor in a separate step can be omitted.

The reactor of the present invention is also suitable for a reactor used in an alternating magnetic field having a frequency of 1 to 50 kHz, for example, a reactor used in the above hybrid vehicle, fuel cell vehicle, electric vehicle, or solar power generation booster circuit. Applicable (Claim 6 ).

It is the figure which showed the reactor of one Embodiment of this invention. It is principal part sectional drawing of the reactor of FIG. It is the perspective view which decomposed | disassembled and showed the reactor of FIG. It is the perspective view which decomposed | disassembled and showed the coil coating body of FIG. 3 to the resin coating layer and the coil. It is the figure which looked at the coil of FIG. 4 from the angle different from FIG. 4, and the figure decomposed | disassembled and shown to the upper and lower coils. It is explanatory drawing of the shaping | molding procedure of the coil coating body in the same embodiment. It is explanatory drawing of the formation procedure following FIG. It is process explanatory drawing of the manufacturing method of the reactor of the embodiment. It is explanatory drawing of the shaping | molding method of the coil coating body in the same embodiment. It is explanatory drawing of the shaping | molding method of the core in the embodiment. It is the figure which showed the relationship between the aspect-ratio of a coil longitudinal cross-section, and a weight ratio or a loss ratio. It is the figure which showed the example of 1 form of the reactor of this invention. It is explanatory drawing which showed how to divide the core material at the time of making the core material in a reactor different. It is explanatory drawing which showed the test method of the evaluation of the characteristic when making a composition of a core material different. It is explanatory drawing which showed the position of the temperature measurement point of a core material. It is explanatory drawing of the manufacturing method of Example A-1 and A-3 in Table 2. It is the figure which showed an example of the aluminum case (reactor case). It is the figure which showed other embodiment of this invention. It is the figure which showed an example of the manufacturing method of the reactor of embodiment of FIG. It is principal part sectional drawing which showed an example of the conventional reactor. It is explanatory drawing at the time of demonstrating the problem at the time of injection-molding the core of a reactor.

Next, embodiments of the present invention will be described in detail with reference to the drawings.
In FIG. 1, reference numeral 15 denotes a reactor (choke coil) as an inductance component, and a coil 10 with an insulating coating is embedded in a core 16 made of a soft magnetic resin molded body without gaps and integrated. . That is, the core 16 is manufactured so as to be a reactor having a structure without a gap.

  In this embodiment, the coil 10 is a flat-wise coil as shown in FIGS. 4 to 6A, in which a flat wire is wound in the thickness direction (radial direction) of the wire, and overlapped to form a coil shape. Wires adjacent in the radial direction in a free-form state processed and formed overlap each other in a contact state.

In this embodiment, the coil 10 includes an upper coil block (hereinafter simply referred to as the upper coil) 10-1 and a lower coil block (hereinafter simply referred to as the lower coil) 10-2 as shown in FIGS. The coil 20 is vertically stacked in two stages so that the winding direction is opposite to each other, and the end portions 20 on the respective inner diameter sides are joined to form a single continuous coil. However, the upper coil 10-1 and the lower coil 10-2 may be continuously formed by one wire.
Since a large potential difference is generated between the upper coil 10-1 and the lower coil 10-2, an annular insulating sheet 21 is interposed between them as shown in FIG. It is. Here, the insulating sheet 21 has a thickness of about 0.5 mm.
In the figure, reference numeral 18 denotes a coil terminal in the coil 10, which protrudes outward in the radial direction.

  As shown in FIG. 5 (A), the upper coil 10-1 and the lower coil 10-2 have the same shape, and both have a circular shape in plan view, and therefore the entire coil 10 also has an annular shape. ing.

As shown in FIG. 2, the upper coil 10-1 and the lower coil 10-2 have the same vertical dimension in the coil axis direction, and the total height dimension of these two coils is A. It is said that. This height dimension A is a dimension including the insulating sheet 21.
In addition, a width dimension which is a radial dimension in the longitudinal section is B.
Thus, the aspect ratio A / B, which is the ratio between the height dimension A and the width dimension B, is set within the range of 0.7 to 1.8.
As shown in FIG. 1, the coil 10 is entirely embedded in the core 16 so as to be embedded in the core 16 except for a part on the distal end side of the coil terminal 18.

  In this embodiment, the coil 10 can be made of various materials such as copper, aluminum, copper alloy, aluminum alloy (however, in this embodiment, the coil 10 is made of copper).

  In the present embodiment, the core 16 is formed of a molded body obtained by injection molding a mixed material of soft magnetic powder and thermoplastic resin.

The coil 10 with an insulating coating is entirely covered with an electrically insulating resin except for a part on the tip side of the coil terminal 18.
In FIG. 1 to FIG. 3, reference numeral 24 denotes a coil covering body composed of a coil 10 and a resin coating layer 22.
In this embodiment, the thickness of the resin coating layer 22 is preferably set to 0.5 to 2.0 mm.
The resin coating layer 22 is made of an electrically insulating thermoplastic resin that does not contain soft magnetic powder. As the thermoplastic resin, PPS, PA12, PA6, PA6T, POM, PE, PES, PVC, EVA and other various materials can be used.

As is also shown in the exploded view of FIG. 3, the core 16 is by injection molding the primary molded body 16-1 and a secondary molded body 16-2 at the interface P ₁ shown in FIG. 1 (B) It is configured to be integrated by bonding.
As shown in FIGS. 1 to 3, the primary molded body 16-1 has a cylindrical outer peripheral side molded portion 25 that is in contact with the outer peripheral surface of the coil cover body 24, and a bottom portion that is located on the lower side of the coil cover body 24 in the drawing. 26 and a shape having an opening 30 at the upper end in the drawing in the coil axis direction.
Note that a cutout portion 28 is provided in the outer peripheral side molding portion 25 of the primary molded body 16-1.
The notch 28 is for fitting a thick portion 36 (see FIG. 3) of the coil cover 24 described later.

  On the other hand, as shown in FIGS. 1 to 3, the secondary molded body 16-2 is in contact with the inner peripheral surface of the coil covering body 24 and fills a space inside the coil 10 to form the primary molded body 16-1. Of the primary molded body 16-1 by closing the opening 30 in the primary molded body 16-1 which is located on the upper side in the figure of the inner circumferential side molded section 32 and the coil covering body 24 reaching the bottom portion 26 in FIG. A recess 40 and an upper circular lid 34 that conceals the coil covering 24 accommodated therein are integrally provided.

On the other hand, the resin coating layer 22 covering the coil 10 is also composed of a primary molded body 22-1 and a secondary molded body 22-2 as shown in the exploded view of FIG. It is integrated by joining by injection molding at a boundary surface P ₂ shown in 1 (B).

The primary molded body 22-1 integrally includes a cylindrical outer peripheral covering portion 46 that covers the outer peripheral surface of the coil 10 and a lower covering portion 48 that covers the entire lower end surface of the coil 10.
On the other hand, the secondary molded body 22-2 integrally includes a cylindrical inner peripheral covering portion 50 that covers the inner peripheral surface of the coil 10 and an upper covering portion 52 that covers the entire upper end surface of the coil 10. Yes.
The primary molded body 22-1 is formed with a thick portion 36 protruding outward in the radial direction over the entire height, and a pair of slits 38 penetrating the thick portion 36 in the radial direction. Is formed.
The pair of coil terminals 18 in the coil 10 penetrates the slits 38 and protrudes outward in the radial direction of the primary molded body 22-1.
In addition, a tongue-like protrusion 42 that protrudes radially outward is formed integrally with the upper covering portion 52 in the secondary molded body 22-2. The upper surface of the thick portion 36 of the primary molded body 22-1 is covered with the protrusion 42.

3 to 10 specifically show a method for manufacturing the reactor 15 shown in FIG.
In this embodiment, the resin coating layer 22 is formed so as to wrap the coil 10 with the insulating coating shown in FIG. 6A from the outside according to the procedure shown in FIGS. 6 and 7, and the coil 10 and the resin coating layer 22 are formed. An integrated coil cover 24 is formed.

  At this time, as shown in FIG. 6B, first, the primary molded body 22-1 having the outer peripheral covering portion 46 and the lower covering portion 48 integrally is formed, and thereafter, as shown in FIG. 7C. A secondary molded body 22-2 having the inner peripheral covering portion 50 and the upper covering portion 52 integrally is formed, and the entire resin coating layer 22 is formed.

FIG. 9 shows a specific molding method at that time.
In FIG. 9A, 54 is a primary molding die for the coil covering 24, specifically, the resin coating layer 22, and has an upper die 56 and a lower die 58.
Here, the lower mold 58 has a middle mold part 58A and an outer mold part 58B.

In the primary molding using the primary molding die 54 shown in FIG. 9A, the coil 10 is first set on the primary molding die 54. At this time, the coil 10 is set with the up and down directions opposite to those shown in FIG.
Specifically, it is set in the primary mold 54 so that the lower coil 10-2 is located on the upper side and the upper coil 10-1 is located on the lower side so that the upper and lower sides are reversed.
Then, the middle mold portion 58A is brought into contact with the inner peripheral surface of the coil 10, and the inner peripheral surface of the coil 10 is restrained and held in the radial direction by the middle mold portion 58A.

Then, a resin (thermoplastic resin) material is injected through a passage 68 into a primary molding cavity 66 formed on the outer peripheral side of the coil 10 of the primary mold 54, and a resin coating layer shown in FIGS. 1 and 6B. The primary molded body 22-1 of 22 is injection molded.
Specifically, a primary molded body 22-1 having an outer peripheral covering portion 46 and a lower covering portion 48 shown in FIG.

When the primary molded body 22-1 of the resin coating layer 22 is molded as described above, together with the coil 10 integrated therewith, they are set in the secondary molding die 70 shown in FIG. 9B.
At this time, as shown in FIG. 9B, the coil 10 and the primary molded body 22-1 are turned upside down and set in the secondary molding die 70.
The secondary mold 70 includes an upper mold 72 and a lower mold 74. The lower die 74 has a middle die portion 74A and an outer die portion 74B.
The secondary molding die 70 forms a secondary molding cavity 80 on the inner peripheral side and the upper side in a state where the primary molded body 22-1 is set together with the coil 10.

  In the secondary molding using the secondary molding die 70, the same resin material as that in the primary molding is injected into the secondary molding cavity 80 through the passage 82, and the secondary molded body 22 in the resin coating layer 22 is injected. -2 is injection-molded and simultaneously integrated with the primary molded body 22-1 and the coil 10.

In the present embodiment, the coil covering body 24 formed as described above is integrated with the core 16 when the core 16 of FIG. 1 is formed.
The specific procedure is shown in FIGS.
In this embodiment, when the entire core 16 is molded, a primary molded body 16-1 having a container shape is first molded in advance as shown in FIG.

  Thereafter, as shown in FIG. 8 (A), the coil covering 24 molded in the procedure shown in FIGS. 6 and 7 is placed in the recess 40 of the primary molded body 16-1 having a container shape. The next molded body 16-1 is fitted over the entire height downward through the opening 30 in the figure, and the coil covering body 24 is held by the primary molded body 16-1.

  In this state, the primary molded body 16-1 and the coil covering body 24 are set in a molding die, the secondary molded body 16-2 in the core 16 is injection-molded, and this is formed into the primary molded body 16-1 and The coil cover 24 is integrated.

FIG. 10A shows a primary mold for the core 16 for molding the primary molded body 16-1.
Reference numeral 84 denotes a primary mold for molding the primary molded body 16-1, and has an upper mold 86 and a lower mold 88.

  Here, the mixed material of the soft magnetic powder and the thermoplastic resin is injection-molded into the cavity 94 through the passage 92, thereby forming the primary molded body 16-1 having the outer peripheral side molded portion 25 and the bottom portion 26 integrally.

FIG. 10B shows a secondary mold for molding the secondary molded body 16-2 in the core 16.
Reference numeral 96 denotes the secondary mold, which has an upper mold 98 and a lower mold 100.
In this secondary molding, the coil covering body 24 is fitted and held in the previously molded primary molded body 16-1, and these are set in the secondary molding die 96.

At this time, the outer peripheral surface of the primary molded body 16-1 is positioned in the radial direction by contact over the entire periphery to the secondary molding die 96, and the lower surface of the bottom portion 26 is vertically moved in the secondary molding die 96. It is held in the positioning state.
That is, the coil covering body 24 is positioned and held in the secondary molding die 96 in the radial direction and also in the vertical direction via the primary molded body 16-1.

In this secondary molding, the same mixed material as that in the primary molding is injected into the cavity 104 through the passage 102 in the figure above the cavity 104 in this state, and FIG. 1 (B), FIG. 3 and FIG. The secondary molded body 16-2 of 8 (B) is molded, and at the same time, it is integrated with the primary molded body 16-1 and the coil covering body 24.
Here, the reactor 15 shown in FIGS. 1 and 8B is obtained.

  In the present embodiment as described above, in a state where the coil 10 with the insulating coating is covered and protected by the resin coating layer 22 from the outside, the mixed material of the soft magnetic powder and the thermoplastic resin is injected to form the core 16. Since it is molded, soft magnetic powder such as iron powder contained in the mixed material does not directly hit or rub against the insulating coating of the coil 10 at the time of injection. It is possible to effectively prevent the insulating coating from being damaged by the contact with the soft magnetic powder.

Further, since the resin coating layer 22 is interposed between the core 16 and the insulating film of the coil 10 as a protective layer or a buffer layer, the thermal stress accompanying expansion and contraction of the core 16 does not directly act on the insulating film. Therefore, the problem of damage to the insulating film due to the thermal stress can also be solved.
Moreover, since the coil 10 forms the coil covering 24 integrated with the resin coating layer 22, it is possible to satisfactorily prevent the coil 10 from being deformed when the core 16 is injection molded.

  In this embodiment, the step of injection molding the core 16 is performed by performing primary molding in advance on the primary molded body 16-1 including the cylindrical outer peripheral side molded portion 25 that is in contact with the outer peripheral surface of the coil covering 24. And the secondary molding step of molding the secondary molded body 16-2 including the inner circumferential side molded portion 32 in contact with the inner circumferential surface of the coil covering 24, and in the secondary molding step, The coil covering body 24 is fitted into the outer peripheral side molded portion 25 of the primary molded body 16-1 obtained by the injection molding, and the outer peripheral side molded portion is formed by the core secondary molding die 96. The secondary molded body 16-2 including the inner peripheral side molded portion 32 is molded while being constrained and held in the radial direction from the outer peripheral side, and simultaneously integrated with the primary molded body 16-1 and the coil covering body 24. To do.

  That is, in this embodiment, since the outer peripheral side molding portion 25 in the core 16 is separately molded in advance as the primary molded body 16-1 separately from the coil 10, it is positioned inside the core 16 during molding. The problem that the outer peripheral side molded part 25 cracks due to the coil 10 does not occur.

In this embodiment, the core secondary molded body 16-is also formed in a state where the coil covering body 24, that is, the coil 10 is positioned and held by the secondary molding die 96 for the core 16 via the primary molded body 16-1. 2, the coil 10 can be prevented from being displaced from the set position by the injection pressure and the flow pressure at that time, and the core 16 can be held in a state where the coil 10 is accurately positioned and held at a preset position. Molding can be completed.
Therefore, it is possible to satisfactorily prevent adverse effects on the characteristics of the reactor 15 due to the displacement of the coil 10 during the molding of the core 16.

  Furthermore, since the secondary molded body 16-2 is molded in a state where the coil covering body 24 is accommodated and held in the recess 40 of the primary molded body 16-1 having a container shape, the molding workability is improved. When the secondary molded body 16-2 is molded, the coil coated body 24 can be positioned and held in the vertical direction that is the coil axis direction by the primary molded body 16-1 itself.

  In the present embodiment, when the resin coating layer 22 of the coil coating body 24 is injection-molded, the molding is performed in at least two times, so that the coil 10 is molded in a state where the coil 10 is well positioned and held by the molding die. It is possible to prevent the coil 10 from being displaced due to injection pressure or fluid pressure during molding.

  In the present embodiment, the secondary molded body 16-2 of the core 16 is injection-molded in a state where the coil covering body 24 is set in the secondary molding die 96 for the core together with the primary molded body 16-1 of the core 16. At this time, the primary molded body 22-1 and the secondary molded body 22-2 in the resin coating layer 22 are applied to the inner peripheral coating portion 50 and the upper coating portion 52 of the resin coating layer 22 to which injection pressure or fluid pressure acts strongly. Since the joint is not located, it is possible to satisfactorily avoid the soft magnetic powder from entering the gap of the joint under a strong injection pressure and damaging the insulating coating 12 of the coil 10.

The coil 15 in the reactor 15 is configured using a flatwise coil and an edgewise coil, and the weight of the reactor is varied by changing the aspect ratio A / B of the longitudinal section of the coil without changing the total number of turns and the cross-sectional area of the rectangular wire. The effect on reduction and loss reduction was investigated.
The results are shown in Table 1.

In Table 1, Comparative Example 1 is an example in which the edgewise coil is in the form shown in FIG. 20, that is, an edgewise coil having a continuous form without overlapping coil blocks, and the reactor of Comparative Example 1 is generally used in the past. It is of the form used.
Therefore, in Table 1, the characteristics such as the weight ratio and loss ratio of each example and each other comparative example are evaluated based on this (100).

  Comparative Example 2 is an example in which the flatwise coil is used alone without overlapping the coil blocks, and in Example 1, the edgewise coil is divided into an inner peripheral coil block and an outer peripheral coil block. Example 2 in which the two are overlapped in the radial direction so that the winding directions are opposite and arranged in two rows and connected on the lower side, Example 2 divides the flatwise coil into upper and lower coil blocks, and how to wind them This is an example in which two layers are arranged vertically so as to be opposite and connected on the inner periphery.

  Similarly, in Example 3, Comparative Example 3, and Comparative Example 4, the flatwise coil is similarly divided into upper and lower coil blocks, and they are arranged in two tiers in the vertical direction so that the winding directions are opposite and connected on the inner circumference. In this example, the flatness is lowered while the cross-sectional area of the rectangular wire is kept the same as in Example 2. The flatness of the flat wire is 11.25, 8.33, 5.0, 3.45 in the order of Example 2, Example 3, Comparative Example 3, and Comparative Example 4, respectively.

  Furthermore, Example 4 divides the flatwise coil into three coil blocks in the vertical direction, and arranges them in three layers up and down so that the upper and lower coils are opposite to the central coil in the winding direction. In this example, the lower and center coils are connected on the inner periphery, and the center and upper coils are connected on the outer periphery. In Example 5 and Comparative Example 5, the edgewise coil is divided into two coil blocks of the inner peripheral side and the outer peripheral side, and these are arranged in two rows so as to overlap in the radial direction so that the winding methods are opposite. In this example, the flatness is lowered while the cross-sectional area of the rectangular wire is kept the same as in Example 1. The flatness of the flat wire is 11.25, 5.0, and 3.45 in the order of Example 1, Example 5, and Comparative Example 5, respectively.

(a) Reactor configuration In the examples and comparative examples shown in Table 1, Fe-2Si (mass%) composition was used as the soft magnetic powder of the core material.

Furthermore, when the coil block is arranged so as to be overlapped vertically or radially, an insulating sheet having a thickness of 0.5 mm is interposed in the middle.
The value of A / B in Table 1 is the value including the insulating sheet.
In all of the examples and comparative examples, the core material is soft magnetic powder, and soft magnetic powder sprayed with argon gas is used. The powder heat treatment is 750 ° C. × 3 in hydrogen for the purpose of preventing oxidation and reducing action. Went for hours. In addition, assuming that the core material is used in an alternating magnetic field of 1 to 50 kHz, the soft magnetic powder used was sieved to 250 μm or less after powder heat treatment.

Next, from the viewpoint of controlling the magnetic permeability within an appropriate range, increasing the thermal conductivity, and from the viewpoint of fluidity in the mold, the soft magnetic powder is blended with 65% by volume of PPS (polyphenylene sulfide) resin and Mixed. The resin was melted at about 300 ° C. by a biaxial kneader and kneaded with soft magnetic powder to form a pellet.
The pellet-like soft magnetic kneaded product was heated at about 300 ° C. by a horizontal in-line screw injection molding apparatus to be in a molten state, and injected into a mold, and then cooled to produce a core material.
As the material characteristics of the core material, the initial relative permeability was about 14.6, and the magnetic saturation density was about 1.3 Tesla. The volume resistivity is 3 to 10 × 10 ⁻³ Ω · m, the thermal conductivity is 2.0 to 3.5 W / (m · K), and the specific heat is 0.6 to 0.65 kJ / (kg · K). there were. The Young's modulus was 20 to 25 GPa, the Poisson's ratio was 0.3 to 0.35, and the linear expansion coefficient was 2 to 3 × 10 ⁻⁵ K ⁻¹ .

The coil used was a rectangular wire with an enamel coating (insulating coating) of pure copper from the viewpoint of reducing electrical resistance and reducing the skin effect. The enamel film was made of polyamideimide resin from the viewpoint of heat resistance, and the film thickness was 20 to 30 μm.
The resin coating layer 22 is made of PPS resin in order to withstand a withstand voltage of 3000 V or more, and the thickness thereof is 0.5 mm on the inner circumference side of the coil and 1 mm on the outer circumference side and the upper and lower surface sides.
In addition, the axial center of the core and the axial center are aligned so that the axial center of the coil and the axial center coincide with each other.

(b) Evaluation method All the characteristic evaluations were performed in a state where the reactor 15 was housed in an aluminum case (reactor case) 114 having a container part 110 and a lid part 112 shown in FIG.
Here, the thickness of the aluminum case 114 was 5 mm.
The aluminum case 114 and the reactor were fixed with a silicone resin.

(c) Inductance measurement Inductance measurement is performed by incorporating the reactor 15 contained in the aluminum case 114 into a step-up chopper circuit and driving the circuit by passing a predetermined superimposed current at an input voltage of 300 V, a boosted voltage of 600 V, and a switching frequency of 10 kHz. It was. The waveform of the current flowing through the reactor (measured with a clamp-type ammeter attached to one terminal) was measured, and the inductance was calculated from the slope of the current waveform at a certain time interval.

(d) Loss measurement The loss was measured by the following method.
The reactor 15 contained in the aluminum case 114 was fixed on the water cooling plate. At this time, the heat conductive grease was thinly applied between the water cooling plate and the aluminum case 114.
Driven by the same step-up chopper circuit as the inductance measurement under the condition of 10 kHz from 300 V to 600 V with superimposed currents of 0 A and 50 A, until it reaches a thermal steady state (a state in which the internal temperature of the core and the cooling water temperature do not change over time) Continuous operation. The cooling water was controlled to flow at 50 ° C. and 10 liters per minute with a chiller (constant temperature water circulation device).
The temperature inside the core at this time was measured at several points, and the highest temperature was taken as the internal temperature. The temperature was measured at 11 points in FIG. 15, and a thermocouple was embedded therein for measurement. However, instead of embedding in the same cross section, eleven measurement points were arranged while gradually shifting in the circumferential direction in order to avoid the effect of embedding adjacent points.
At this time, the amount of heat is measured from the difference between the flow rate of the cooling water in the water cooling plate and the temperature on the inlet side and the outlet side, the value of superimposed current 0A is iron loss, the value of superimposed current 50A is total loss, total loss-iron The loss was defined as a copper loss with a superimposed current of 50A.

  Here, at the superimposed current 0A, the coil hardly generates heat, and the copper loss is considered to be zero. Therefore, the total loss at the superimposed current of 0 A = iron loss. The iron loss is considered constant because it does not depend on the superimposed current. Therefore, if the iron loss is subtracted from the total loss of the superimposed current 50A, the remainder is the copper loss at the superimposed current 50A. However, it is assumed that the heat generation of the coil due to the current amplitude obtained by removing the DC superimposed current from the current flowing through the reactor is small.

The weight ratio and loss ratio of each example and other comparative examples based on Comparative Example 1 in Table 1 are shown in FIG.
In the figure, the horizontal axis represents the aspect ratio A / B, and the vertical axis represents the weight ratio (FIG. 11A) and the loss ratio (FIG. 11B).
11A and 11B, the aspect ratio A / B of the coil longitudinal section is within the range of 0.7 to 1.8, so that the inductance is maintained substantially equal to that of the comparative example 1 while comparing. It can be seen that the weight ratio and loss can be reduced to 99% or less compared to Example 1.
The reason why the tendency to A / B is slightly different between the weight ratio and the loss ratio is thought to be due to the influence of the loss due to the skin effect due to the difference in flatness of the flat wire. More specifically, since the copper loss increases due to the skin effect when the flatness is small, the loss changes more greatly than the change in the weight of the coil. This is why the A / B range is 0.65 to 2.0 in FIG. 11A and the A / B range is 0.7 to 1.8 in FIG.

In addition, the ratio of the core diameter of the coil inner peripheral portion to the peripheral length of the coil longitudinal section (core diameter of the coil inner peripheral portion / peripheral length of the coil vertical cross section) is 0.81 in the first embodiment and in the second embodiment. 0.86, Example 3 is 0.87, Example 4 is 0.84, and Example 5 is 0.86.
As described above, in the present invention, it is desirable that the ratio of the core diameter of the coil inner peripheral side portion and the peripheral length of the coil longitudinal section be 0.8 or more.

By the way, in the case of a reactor in which the coil is embedded and integrated in the core, the core generates a large amount of heat when trying to secure a high inductance, while the inductance decreases when trying to suppress the heat generation to a low level. There are inherent problems such as
Specifically, Fe-Si based Fe-based alloy powders are generally used as soft magnetic powders for cores in conventional reactors. However, this can reduce magnetostriction by adding Si to Fe, and therefore the magnetostriction is reduced. This is because the resulting core vibration can be suppressed small.

When Si is contained in Fe, the magnetostriction decreases as the Si content increases. The magnetostriction becomes zero when the Si content is 6.5%, and the magnetostriction becomes negative when it exceeds 6.5%. (The magnetostriction is positive at 6.5% or less). On the other hand, the core loss becomes minimum at 6.5%, and the core loss increases even if the amount of Si increases or decreases.
Therefore, from the viewpoint of magnetostriction and core vibration resulting therefrom, a composition containing 6.5% Si is preferable.

  A reactor using a soft magnetic powder having a composition of Fe-6.5% Si as a core soft magnetic powder also has low core loss and small heat generation during operation, but on the other hand, the inductance is not sufficiently high. Have the following disadvantages.

On the other hand, when the Si content is reduced to 3% or 2% and the value approaches that of pure Fe, the inductance increases, but conversely, the core loss increases and the heat generation also increases.
If the heat generation increases, the temperature rise of the reactor becomes large, the reactor reaches a high temperature, and in some cases, a portion exceeding the allowable maximum temperature set inside the core material appears.

For example, a reactor used in a booster circuit of an automobile is a component that is used for a very long time, and if the temperature rise is repeated for a long period of time, the resin as a binder deteriorates due to the thermal history, which in turn shortens the component life. It leads to.
For this reason, an allowable reached temperature (maximum temperature) is set for the reactor, and the temperature rise due to internal heat generation is required to be suppressed below the set maximum temperature.

In this respect, in the case of the reactor using the soft magnetic powder having the above-described Fe-6.5Si-based composition as the soft magnetic powder of the core material, heat generation in the core material is small, and the ultimate temperature is below the set maximum ultimate temperature. Can be satisfactorily suppressed.
However, on the other hand, the inductance characteristic originally required as a reactor becomes insufficient.

On the other hand, in the case of using a material close to pure Fe with a low Si content, although the inductance characteristics are sufficient, the heat generation inside the core material is large, and the ultimate temperature is set below the set maximum temperature. It is difficult to suppress.
In addition, when an intermediate, for example, Fe-3Si composition is used, both the inductance and heat generation characteristics become halfway, and there are cases where none of the characteristics can be satisfied.

  Therefore, as the reactor, the inner peripheral portion and the outer peripheral portion of the coil in the core are made of different materials, and the outer peripheral portion is made of 0.2 to 4.0 mass% of pure Fe or Si as a soft magnetic powder. It is composed of a core material with high inductance and high heat generation containing the Fe-based soft magnetic alloy powder, and the inner peripheral side portion contains 1.5 to 9.0% by mass of Si as the soft magnetic powder, and the outer peripheral side. It may be composed of a core material that contains Fe-based soft magnetic alloy powder having a higher Si content than the soft magnetic powder of the core material and has a relatively lower heat generation and lower inductance than the outer peripheral portion. desirable.

  In particular, the Si content of the soft magnetic powder on the inner peripheral side portion should be increased so as to be more than 1.5% by mass than the Si content of the soft magnetic powder on the outer peripheral side portion. The Si content of the portion of the soft magnetic powder is preferably 2.5% by mass or more, and more preferably 3.5% by mass or more, more than the Si content of the soft magnetic powder of the outer peripheral side portion.

In the core, there is a situation that the outer peripheral portion of the coil is easily cooled, while the inner peripheral portion is difficult to cool. In view of this, the outer peripheral portion that is easy to be cooled can obtain high inductance while generating heat. Made of a core material containing Fe-based soft magnetic alloy powder containing 0.2 to 4.0 mass% of pure Fe or Si having a large size, while cooling is difficult and the inner peripheral side portion where heat is difficult to escape is Si It is convenient to use a core material containing a high Si Fe-based soft magnetic alloy powder containing 1.5 to 9.0%.
By doing in this way, it is possible to obtain a reactor that can satisfy both conflicting characteristics of inductance and suppression of heat generation.
The following is a concrete clarification of this point.

  As shown in FIG. 13, the outer peripheral side molding part (outer peripheral part) 25, the inner peripheral side molding part (inner peripheral side part) 32, the bottom part (lower surface part) 26, and the lid part (upper surface part) of the core 16 in the reactor 15. 34 was composed of a core material using soft magnetic powders having the compositions shown in Tables 2 and 3, and inductance measurement and maximum temperature measurement were performed for each.

Here, for Examples B-1 to B-9 and Examples A-1 to A-4, the reactor 15 was manufactured according to the above manufacturing method.
On the other hand, for Example A-5, the reactor 15 was manufactured by the manufacturing method shown in FIG.
That is, in Example A-5, the primary molded body 16-1 having the bottom portion 26 and the outer peripheral side molded portion 25 is preliminarily molded alone, and the inner peripheral side molding in the secondary molded body 16-2 in FIG. The portion 32 is similarly preliminarily molded in advance, and the coil covering body 24 is fitted into the primary molded body 16-1 in an internally fitted state, and further, the inner peripheral side molding is separately molded in advance inside the coil covering body 24. The portion 32 is set in an internally fitted state, and is set in a molding die in a combined state, and the lid portion 34 in the secondary molded body 16-2 in FIG. 3 is injection-molded. At the same time, this is formed into a primary molded body. 16-1, integrated with the coil covering body 24 and the inner peripheral side molding portion 32, the reactor 15 was manufactured.
On the other hand, for A-6, the outer peripheral side molded portion 25 and the bottom portion 26 of the primary molded body 16-1 are separately molded separately, and the other secondary molded body 16-2, specifically, the inner peripheral side molded portion 32 is formed. And the lid 34 were molded by the method shown in FIGS.

(a) Structure of reactor The structure of the reactor 15 manufactured here is as follows.
In each example, the core material was composed of gas spray powder as a soft magnetic powder and mixed with PPS (polyphenylene sulfide) resin in a composition of 60% by volume.
The coil 10 is an upper coil in which a flat copper rectangular wire (with wire thickness of 0.85 mm and width of 9 mm) with an insulating coating made of polyamideimide resin (film thickness is 20 to 30 μm) is used and is flat-wise wound. 10-1 and the lower coil 10-2 were stacked in two steps, and the inner peripheral side ends 20 were connected to each other, and this was reinsulated with polyimide tape.

As shown in FIG. 5B, the upper coil 10-1 and the lower coil 10-2 are overlapped with each other by inverting the upper coil 10-1 with respect to the lower coil 10-2, To flow in the same direction of rotation.
The dimensions were such that the inner diameter of the coil was 47 mm and the number of turns was 18 for both the lower coil 10-2 and the upper coil 10-1, for a total of 36 turns.
In addition, an insulating sheet 21 having a thickness of 0.5 mm was interposed between the upper coil 10-1 and the lower coil 10-2.
The core 16 encloses the coil 10 in an embedded state with no gap, and the dimensions are a core outer diameter of φ90 mm and a core height of 40.5 mm.
The axial center of the core 16 and the axial center of the coil 10 and the axial center of the core 16 and the axial center of the coil 10 are arranged so as to coincide with each other. The same applies to all examples).

As the material characteristics of this core material, the initial relative magnetic permeability is about 13.8 when the soft magnetic powder is pure Fe, about 13.5 for 2% Si, about 13.0 for 3% Si, 4% It was about 12.6 for Si, about 12.0 for 5% Si, and about 11.1 for 6.5% Si. Magnetic saturation density is about 1.3 Tesla for pure Fe, about 1.2 Tesla for 2% Si, about 1.17 Tesla for 3% Si, about 1.14 Tesla for 4% Si, about 1.14 Tesla for 4% Si, about 5 Te It was about 1.02 Tesla with 1.09 Tesla and 6.5% Si. The core material of any composition has a volume resistivity of 3 to 10 × 10 ⁻³ Ω · m, a thermal conductivity of 2.0 to 3.5 W / (m · K), and a specific heat of 0.6 to 0.65 kJ. / (Kg · K). The Young's modulus was 20 to 25 GPa, the Poisson's ratio was 0.3 to 0.35, and the linear expansion coefficient was 2 to 3 × 10 ⁻⁵ K ⁻¹ .

(b-1) Measurement of inductance Inductance was measured by the same method as described in the above example.
(b-2) Maximum temperature measurement
(b-2-1) Maximum temperature measurement during water cooling The maximum temperature measurement during water cooling was performed as follows.
The reactor contained in the aluminum case 114 was fixed on a water-cooled plate. At this time, the heat conductive grease was thinly applied between the water cooling plate and the aluminum case 114.
It is driven by the same step-up chopper circuit as the inductance measurement under the condition of 10 kHz from 300 V to 600 V with superimposed current 50 A and continuously operated until it reaches a steady state (a state in which the internal temperature of the core and the cooling water temperature do not change with time). I let you. The cooling water was controlled to flow at 50 ° C. and 10 liters per minute with a chiller (constant temperature water circulation device). The temperature inside the reactor at this time is measured at several points, and the highest temperature is set as the maximum temperature. The temperature measurement points were measured by embedding thermocouples at 11 points in FIG. However, instead of embedding in the same cross section, eleven measurement points were arranged while gradually shifting in the circumferential direction in order to avoid the effect of embedding adjacent points.
The measurement results were the highest at the position of point H in FIG.
The allowable temperature was set to 115 ° C. from the viewpoint of the difference between the actual use conditions and the present evaluation method and the heat resistant temperature and life of the used member.
These results are also shown in Table 2.

(b-2-2) Maximum temperature measurement during air cooling Maximum temperature measurement during air cooling was performed as follows.
The reactor 15 was housed in an aluminum case 114 with fins 116 shown in FIG. 17, and an air cooling fan was fixed at a position of 20 mm so that cooling air would flow from the upper and lower surfaces toward the aluminum case 114 with fins 116. At this time, the ambient temperature is kept at 30 ° C.
The flow rate of one fan is 3000 liters per minute.
It is driven by the same step-up chopper circuit as the inductance measurement under the condition of 10 kHz from 300 V to 600 V with superimposed current 30 A, and continuously operated until it reaches a steady state (a state in which the internal temperature of the core and the cooling water temperature do not change with time). I let you.
The temperature inside the reactor at this time was measured at several points, and the highest temperature was taken as the maximum temperature. The temperature was measured at 11 points in FIG. 15, and a thermocouple was embedded therein for measurement. However, instead of embedding in the same cross section, eleven measurement points were arranged while gradually shifting in the circumferential direction in order to avoid the effect of embedding adjacent points.
The measurement results were the highest at the position of point H in FIG.
In addition, the allowable temperature was set to 130 ° C. from the viewpoint of the difference between actually used conditions and this evaluation method, and the heat resistant temperature and life of the used member.
The results are also shown in Table 3.

  From the results of Tables 2 and 3, it can be seen that the characteristics of the inductance and the maximum temperature can be satisfied by configuring the material of each part of the core 16 in the reactor 15 according to the above.

In Tables 2 and 3, for convenience, the bottom portion 26 of the primary molded body 16-1 is the lower surface portion and the lid portion 34 of the secondary molded body 16-2 is the upper surface portion. It is also assumed that it is installed upside down with respect to the above figure. In this case, the lid portion 34 is a lower surface portion and the bottom portion 26 is an upper surface portion.
Therefore, in such a case, the bottom portion 26 is used as the upper surface portion and the lid portion 34 is used as the lower surface portion, and this is made of the materials shown in Tables 2 and 3.

18 and 19 show another embodiment of the present invention.
In this embodiment, the core 16 in the reactor 15 is integrated with the container portion 110 of the aluminum case (metal reactor case) 114, specifically, here, one of the cores 16 having the bottom portion 40 and the outer peripheral side molding portion 25. This is an example in which the next molded body 16-1 is injection-molded integrally with the container portion 110.

Here, after the container part 110 of the aluminum case 114 and the primary molded body 16-1 are integrated by injection molding, the coil covering body 24 is set therein so as to be fitted therein, and then the secondary molded body in the core 16 is set. 16-2 is injection-molded by the molding method shown in FIG. 19 and integrated with other parts.
Thereafter, the lid portion 112 of the aluminum case (reactor case) 114 shown in FIG. 18B is covered, and the reactor 15 is placed inside the aluminum case 114.

  In this example, when the core 16 is injection-molded using the core 16 being an injection-molded body, specifically, the primary molded body 16-1 is made into a container portion of a metal aluminum case 114. 110, the container portion 110 of the aluminum case 114 is formed into the core 16 of the reactor 15 in a separate process after the core 16 is formed, that is, after the reactor 15 is manufactured. The process of attaching can be omitted.

  Although the embodiments and examples of the present invention have been described in detail above, this is merely an example, and the present invention can be configured in various modifications without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 10 Coil 10-1 Upper coil block 10-2 Lower coil block 15 Reactor 16 Core 16-1, 22-1 Primary molded body 16-2, 22-2 Secondary molded body 22 Resin coating layer 24 Coil coating body 25 Outer periphery Side molding part 30 Opening 32 Inner circumference side molding part 46 Outer circumference coating layer 50 Inner circumference coating layer 54, 84 Primary molding die 66 Primary molding cavity 70, 96 Secondary molding die 80 Secondary molding cavity 110 Container part 114 Aluminum case (Reactor case)

Claims (6)

A reactor containing a coil formed by winding a rectangular wire with an insulating coating inside a core containing soft magnetic powder in a state of being entirely encased in the core,
A form in which a plurality of coil blocks are connected to each other in the height direction and / or radial direction that is the coil axial direction and coaxially stacked via an insulating sheet in a direction orthogonal to the winding direction of the wire rod. The aspect ratio A / B is in the range of 0.7 to 1.8, where A is the height dimension in the longitudinal section of the coil and B is the width dimension that is the radial dimension. Nashitea is,
On the other hand, the coil with the insulating coating is covered with an electrically insulating resin not containing soft magnetic powder so as to be entirely encased from the outside to form a coil covering,
The core is composed of a molded body formed by injection molding the mixed material of the soft magnetic powder and the thermoplastic resin in a state in which the coil covering body is integrally embedded therein,
The resin coating layer of the coil coating body is formed of a thermoplastic resin, and the resin coating layer covers a molded body including an outer peripheral coating portion that covers the outer peripheral surface of the coil, and an inner peripheral surface of the coil. A reactor , wherein a molded body including an inner periphery covering portion is joined and integrated .   2. The reactor according to claim 1, wherein the coil is a flatwise coil formed by winding a rectangular wire in the thickness direction of the wire, and the coil blocks are stacked in a plurality of stages in the height direction.   3. The reactor according to claim 1, wherein the soft magnetic powder is a powder having a composition containing 0.2 to 9.0% by mass of pure Fe or Si. The core according to any one of claims 1 to 3 , wherein the core includes a primary molded body including a cylindrical outer peripheral side molded portion that is in contact with the outer peripheral surface of the coil cover, and an inner periphery that is in contact with the inner peripheral surface of the coil cover. A reactor in which a secondary molded body including a side molded portion is integrally joined at a boundary surface. The reactor according to any one of claims 1 to 4 , wherein the core is injection-molded integrally with a container part of a reactor case. Reactor according to any one of claims 1 to 5, frequency is characterized in that it is used in the alternating magnetic field 1～50KHz.

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